hey oceanography class let's go over chapter 10. it covers a lot of material it's gonna be a long lecture i'm just warning you bear with me please it's on beaches shoreline processes and the coastal ocean so the coastal ocean is a very busy and increasingly busy place humans have been attracted to living around the coast i'm sure maybe even you lived by the coast because of its mild climate right a lot of uh delicious seafood easy transportation and a number of population studies really show that about 50 percent of the world's population which is about 3.5 billion people live along the coastline which is pretty crazy 80 percent of all americans live including myself live within an hour drives of the ocean or the great lakes so um as humans we do enjoy uh living by the coastline and this is going to increase there are studies that show uh people are generally moving toward coastal areas okay um and coastal oceans are filled with a lot of marine life about 95 of all the fish caught in the ocean are obtained within 200 miles of the shore so that's where we like to fish commercially and recreationally really in the coast on the coast there are coastal wetlands which are a vital natural cleanser for storm runoff removal pollutants and a number of really useful things we'll talk about so we'll cover all of these uh these topics in this chapter all right so how do you define a coastal region well the shore okay i'm sure you heard that that is the zone that lies between the lowest tide level or low tide and the highest elevation on land that is affected by storm waves so huge storm maybe even low pressure system like a hurricane when those waves make it up uh landward okay the coast on the other hand that extends inland from the shore as far as there are ocean related features are found i know that's kind of a weird definition in the state of florida then it's hard almost all the landscape features on florida are ocean related features but i guess it's modern ocean related features okay and then the coastline really marks the boundary between the shore and the coast okay so essentially that's the landward limit of the highest storm waves that occur uh on the shore okay all right there's a lot of definitions here don't worry about it we're kind of going to go through them pretty quickly but this is just defining different regions in the coastal area the back shore foreshore shoreline near shore offshore beach and wave cut benches i'll go through these with the image just so that um it makes a little more sense so i'm gonna jump to the next slide this one i guess you can just use for reference okay let me get my handy pen out okay so uh and just so you know uh the authors of this book are um uh authors from uh uh an institution in california so there's a heavy west coast bias to their coastal regions we're going to talk a lot about the east coast but a lot of the examples here are what you would see on the pacific coast and i encourage you uh to go check out that coast if you know uh if you ever wander out towards the pacific or the west side of the united states really beautiful but okay so the shore is divided into the back shore and the foreshore okay so here's the foreshore and then here's the back shore okay um the shoreline migrates back and forth within the tide of the waters etch okay so that's uh this right here so this would be kind of like the high tide mark high tide shoreline and then during low tides this would be the low tide shoreline over here okay the near shore extends from the c word uh from the low tide line to the low tide breaker line okay so that is the near shore which is here all right so that is the low tide uh and these are the breakers the waves breaking um up to where the long shore bars are and these are those long short bars these are just bars of sand that accumulate as kind of tides wax and wane on a daily basis on a beach and they can also move or migrate seasonally okay um offshore beyond the low tide uh breakers that's the offshore zone okay so beyond the uh during low tide you can have breakers form way out here as a result of interacting with the longshore bar this is the offshore area okay a beach is a deposit of the shore area okay it consists of wave worked sediment that's kind of worked back and forth from crashing waves all right and that is this whole area here okay from essentially here to here um on the west coast what you'll find a lot of times are wave cut cliffs sometimes like you have the coastal highway that's up here on this kind of plateau or flat area okay and then you park your car and then you go down some uh steps um and here this would be the wave cut cliff here all right and then the berm is kind of a like a dry gently sloping kind of slightly elevated above the ocean uh portion of the beach that's made up of a lot of sediments they can be the foot of uh where the coastal cliffs are or where there are sand dunes like for example if you're on a um on uh oh god i forgot the name of it long uh barrier island okay and so that berm area is here this is where we like to hang out as humans we come out here to the beach to you know do our recreational activities to lay down lay down the tile hang out picnic whatever it is we're on the on the berm here okay a lot of deposited sand um and then there's the beach face okay this beach face is a kind of flat area it's exposed during uh mostly during uh low tide okay um and this is uh kind of compact sand because it's typically saturated with incoming uh water from the ocean and waves crashing uh it's packed in harder so runners like to run on the beach face so runners sometimes will like time their beach runs for low tide that way they can have the maximum area for the beach face itself okay and then this is the longshore trough all right so if you go out a little further this might be a low-lying area before you run into the longshore bars which we've talked about and then this flat area here is called the wave cut bench all right that kind of sums it up yeah we talked about the berm okay we talked about the beach face oh it can also be called the low tide terrace another way of describing it and the trough separates the long shore bar which is that kind of bar of sand that shows up at the edge or the beginning of the offshore area and that's at the end of the beach face okay so what are the beaches composed of it's they're composed of anything that's local anything that's weathering down whatever rocks are exposed and they're weathering down to the smaller pieces and eventually into sand and being worked by the ocean endlessly crashing on the shoreline right waves on a daily basis there are about 10 000 waves crashing in a 24 hour period so this sediment gets reworked and worked and rounded okay the material can be coarse-grained or fine-grained depending on how far they've traveled and how long they've been worked by the ocean or even rivers a lot of times rivers will develop will deliver a lot of sand and sediment to a beach area or a berm and those that sediments derived from local sources or a little farther away perhaps mountains that are eroding at higher elevations so local cliffs especially in california boulders from local cliffs that can uh mass waste and just landslide downwards can provide a lot of sediment for the beaches sand from rivers and mud those are uh two key sources of material that ends up being piled up on the beach um significant biological material can show up on tropical beaches this is true you guys ever been to um was it sanibel island never tried to walk on that beach barefoot it's pretty it's brutal but it's great for collecting shells well it's a lot of biological material that just piles up um i just went to melbourne beach uh last weekend um and yeah there's a lot of shells there too it's a great place to collect a lot of biological material very nice um and all this material is always in motion and in transit along a shoreline so the water uh the coastal ocean the waves crashing these create currents that helps move the sand okay um and largely in florida for example our sand is derived from uh eroded areas especially eroded areas that are local right and we get a lot of quartz in our sand because that's the most abundant material that's why our sand is kind of a beige or white like a pure white like you would see in panama city beach or destin um if you go further south then you have more a little bit more limestone kind of included or biological material if you go to different beaches around the world especially areas like volcanic areas like say iceland or places in chile or in central america like guatemala or costa rica they have a lot of volcan volcanoes that are local and so there's a an igneous volcanic rock called basalt that breaks down into sediment and you have black sand beaches so there's a lot of variety hawaii also has black sand beaches as well so depending on what's uh what rock is locally available will make up the material you find on a beach okay so sand moves along a beach it's perpendicular to the shoreline uh toward and away like kind of comes toward the shoreline and then gets pulled back out i'm sure you've noticed this if you've been like ankle deep water at the beach you notice that you kind of start sinking into the sand and perhaps feel like you're being pulled into the ocean well that's what happens to sediment okay so there are swash waves and swash waves kind of rush up the beach right they're the ones that kind of sink into the sand that brings sand up to the beach backwash is when that water gets sucked back out into the ocean that's when it drains back to the ocean that typically erodes sand away from the beach area and in total like the general movement of the sand is parallel to the shoreline so let's say this is the shoreline right and your water is like over here you have incoming waves all right colors all right your sand uh will move in this direction okay assuming that this is the the direction of the long shore current that's what this is longshore currents and that helps transport sand along of each okay now incal this is more true in california but some of it rings true here in florida but they deal with like seasonal changes to their beaches in the summertime it's very prevalent there in the summertime they have lightweight wave activity and so what happens to their beach is that they have a very wide and sandy berm okay what that means is that there's a lot of area to hang out in you know to lay in the sand and it's kind of nice and comfortable um yeah we're really spoiled in florida we have a lot of nice sand that we can walk through it makes it very comfortable but not all coastlines are like that not none of them have sand sometimes they're just rocky okay in the summer in the pacific coast typically there's light wave activity then you have a steep beach face okay so this is the beach face is very steep um and what what happens here is that the swash dominates so the incoming water uh waves come in and and the swash uh current brings a lot of sand and piles it up on the beach so you have a lot of sand on the beach because of the light wave activity okay there are no long shore bars present and that's that's typical in in florida in the summers generally speaking there's lighter also lighter wave activity and so the berms also grow a little bit larger as a result not as drastic as in california but so let's go to uh the wintertime beach this is what that same beach looks like in the wintertime look there's no sand no sand this is turn your ankles beach right so all that sand has been eroded away and that's because of the increased wave activity and with increased wave activity you get more backwash and so there's more sediment erosion and so you get a much narrower beach [Music] flattened beach face that you see here and then you get these long shore bars that are present in the close to the offshore area okay and i don't know if you've noticed uh like i guess at the time of me lecturing for this video uh it's november we're approaching the winter time and and so uh there's heavier wave activity even in florida in the winter time okay so the long shore current is this zigzag motion of the water along the shore okay longshore currents that's what helps transport sediment and it moves generally in this direction because the waves are coming in at this angle and we'll talk about why this is in a second but this would be the direction of longshore current and i know if you've had this experience before if you've ever gone to a beach you know you playfully go into the water and throw the ball around hang float wrestle and stuff like that then after like 10 minutes all of a sudden like you look back and you're like mommy right you don't know where your party is anymore you don't know where the you know the your chair is because if you've drifted away you've drifted maybe like you know 40 50 60 feet away from where you parked all your stuff and the reason is for that is because you took a ride on the longshore current and it's pretty slow they can go from uh two and a half miles per hour okay and so the way it works is you have a swash wave come up it dumps sand on the beach and then the but it comes in at kind of an angle and the reason it comes in at angles if you see the waves coming in they're coming in at an angle here remember we talked about refraction right and then once the waves interact with the uh uh ocean floor they start to bend towards the shore but the general direction is this direction from the incoming waves and that's so that'll create a longshore current that moves in this direction okay so we call that longshore transport okay or beach drift or literal drift and it essentially transports a lot of sediment along that direction and it occurs in that surf zone where the waves are crashing and i'm sure you've noticed this like if you get out of the water you notice sand has found its way in all the wrong places in your bathing suit pockets full of sand and that's because the sand is in suspension in the water because there's so much wave activity and that's the sand that's in motion so this current really transports millions of tons of sediment yearly okay and it's its direction is dictated by the wave approach and so like say you have uh let's go coastline like this right if you have incoming waves coming in at an angle like this okay the longshore current will move in this direction if you have uh waves coming in and this and kind of angled in this direction then the longshore current will be in the opposite direction okay but there are general trends the net sediment movement is southward along the atlantic side of the united states and on the pacific net movement is also southward let's take a look at a picture of this okay so here is the let me get red these are the uh net longshore currents along the coast now remember that we're talking about coastal waters very close to the continental margins remember when we talked about um ocean currents these are open ocean currents so here's an eastern boundary cold california current that moves southward as well okay now on on the other side of the united states the atlantic coast uh the longshore current also moves southward okay but the gulf stream which is an open ocean current uh hundreds of uh miles away uh in the open ocean moves in a northward pattern okay and so all the you know here are the appalachian mountains these are rocks exposed at the surface they erode away and there are a number of rivers that deliver a lot of sediment to the east coast the united states that sediment gets worked by the oceans and then moves southward uh to our precious state here in florida that's why we have an abundant uh an abundance of sand and absolutely beautiful beaches okay so there are two major types of shores they're erosional and there are depositional shores erosional shores have well-developed cliffs okay so rural florida out that's not really true here so think of the pacific coast um and and that makes sense because um where you have erosional shores and well-developed cliffs you have tectonic uplift occurring so on the west coast in california and state washington state and oregon they have tectonic boundaries close by they're active margins there are earthquakes and that pushes the land upwards so there's uplift of those coasts and that's why you get those well-developed cliffs depositional shores are our east coast essentially these are shorelines that are gradually subsiding meaning that they're sinking they're made up of a lot of unconsolidated sediment that's been deposited there by rivers delivering delivering all that sediment into into those areas and because it's unconsolidated sediment it'll settle and it starts to sink so a lot of the features of the coastline on the east coast are temporary features with rising sea levels or lowering sea levels things get shifted fairly quickly in terms of geologic time and so on depositional shorelines you'll find barrier islands okay which we have a lot of in florida and a lot of sand deposits sand dunes and things of that nature so here's an example of an erosional shoreline you have protruding bits of land here we call those headlands okay remember because of wave refraction they absorb a lot of the wave energy in these areas a lot of times they can have sea arches okay and surrounding these headlines a lot of times you'll have coves this is where sand deposits because the wave energy has dissipated and sand deposits in these areas so if you're on the west coast a lot of times you come down to these little coves and this is where you can enjoy the beach recreationally then there are sea caves which can be dangerous like there are places where you during low tide you can go in and explore the cave but you got to do it at a specific time during low tide and make sure that flood currents don't come in and then trap you in one of those that'd be a horrible way to go there are sea stacks sea stacks are essentially just remnants of a headland where the sea arch has collapsed and then you're left with this jutting out rock here and then in some cases you have blow holes uh and that's when we have incoming flood currents when you have a increase in the tide uh water could shoot up these blow holes and of course then you have the sea cliffs and then uh a marine terrace a flat lying area up here it's almost like a plateau and then here's the wave cut bench all the way out here very flat feature here this is uh off the coast of portugal you can ride your boats around in between the sea arches so here's a real real world example of this okay again here sea stacks we've talked about this stuff already but i just wanted to give you a real world example the other pretty cool thing about erosional shorelines is that they're undergoing changes all right they this land area oftentimes is being uplifted so tectonically lifted higher than the ocean and so what happens is the ocean erodes and creates these flat wave cut benches it's a typical feature that you'll find here it's pretty cool if you go out during low tide you could see all kinds of organisms that latch on to the rocks here or in the in the tide pools and stuff like that but what happens is when there is uplift this whole land area is uplifted and what you see here see this flat area we call this a marine terrace this was formally a wave cut bench down here but has since been uplifted because of tectonic activity and this has happened numerous times here in this picture you can see that there's a number of different flat former wave cut benches today they're marine terraces as you move away from the current shoreline it's almost like steps as you're going up hill but that's pretty incredible it just shows you the power of how land is uplifted because of tectonic activity okay depositional shorelines on the other hand you're probably more familiar with these there are a lot of features here we'll go over go over them but they're dominant on the atlantic coast all along the east coast this is uh martha's vineyard that's my best box boston action accent there limited fake boston accent so here what you find typically are barrier islands big piles of sand that are parallel to the coastline they're essentially just sand bars this barrier island covers a bay so then they call it a bay barrier okay it seals off a lagoon so this here would be a lagoon okay made up of typically some fresh water and salt water mixed together and then in other areas some barrier islands will curve like this we call those spits okay and they curve inward like that because um the longshore current moves in this direction along with where that hook is so that connects one of the mainland and hooks into a bay so this would be a bay over here okay so you can determine the direction of the longshore current based on how the spit hooks okay on depositional shorelines you can often find tumbleos okay tumbleos are an area here oftentimes they're only exposed during low tide and they're typically behind maybe like a sea island or something like that um and then like i said uh berry islands those are long offshore sand deposits and those are parallel to the coastline okay this example here is in in california but these are the typical coastal features you would find at a depositional coastline so here's your sea island here's your tumbler here's a babe area barrier barrier i don't know i said it like that here's your spit which curve is kind of this way here's your barrier island okay uh here in florida a lot of the um popular beaches are typically barrier island beaches clearwater miami beach [Music] a fort lauderdale beach uh what else oh melvin right this all the space coast new smyrna um all those areas are barrier islands all right and then there are deltas deltas are depositional features as a result of rivers kind of dumping into the ocean we'll talk about that um bear islands uh this is a lot of sand uh parked way out uh parallel to the coastline here these are the outer banks this is north carolina and barrier islands kind of basically go from virginia all the way down right where cape hatteras is there's like a or turn in the barrier island this way and it kind of goes down south this way but these are very popular beaches to visit a lot of northerners during their summer will drive down to the outer banks to enjoy their summer a few weeks of summer vacation perhaps but yeah it's it's uh these bear islands do not exist on erosional shorelines so like in california in the pacific west they don't have barrier islands we do on the east coast and the reason why they're kind of important and helpful say for the the state of north carolina is there they're like the first line of defense for like uh uh storms that come towards the coastline and so they're kind of like a barrier and they block a lot of the high wave activity um a lot of them developed at the end of the last ice age okay so 18 000 years ago sea level was about 400 feet lower than it was today and a lot of the sand was deposited in this in this in these areas uh uh that again these weren't this wasn't the coastline if if sea level was 400 feet lower the coastline would have been further away but a lot of sand uh was deposited here by the rivers uh kind of pushing sand out here and then they were reworked by the ocean to today's configuration and it's quite beautiful the outer banks has a lot of sand dunes the wright brothers that's where they tested a lot of their early models of planes on the sand dunes there so i highly recommend visiting these areas very beautiful even in texas i don't know if you guys ever been to uh if you just go south of houston you can make it to galveston this is on a barrier island or you can go all the way down to mexico right sorry [Music] uh but this is uh padre island in south padre island huge spring break spot but here yes barrier islands okay they're typically separated from the mainland by a lagoon which is like brackish water salt water and river water kind of mixed together and if you know anything i mean especially in florida if you go to south florida and um a lot of these barrier islands are built like miami beach is a village of a city just built on a barrier island and if you think about they're just they're just sandbars so you're building huge buildings on sand it's probably not a good idea in the long run a lot of these structures they can be destroyed by major storms and uh um and the ocean as it erodes away the sand that's why in florida at least we have a lot of recreation projects where we put sand on the beach um here's an example of a heavily populated one especially in the north northeast there's so many people that live up there they come and populate a lot of the barrier islands that are in maryland and new jersey um right so yeah here's the jersey shore guys heavily developed so it's a barrier ireland here's the main land and here's the lagoon okay so there's a good a good example of it so if you wanted to look at uh barrier islands on the east coast united states there are more than 2 000 identified worldwide and 300 along the atlantic and gulf coast we kind of hit some of the major ones the outer banks over here but this goes right through maryland new jersey and into uh kind of the rhode island area here but all along the east coast of florida and even on the west coast over here and then on the panhandle also those beaches are absolutely spectacular and you find bare islands there as well some of them completely in their natural state like saint vincent island i lived in tallahassee for a while so i used to go down to panhandle beaches all the time uh but in as well as uh mississippi alabama and new orleans as well as texas so there are a lot of barrier islands okay so what are the features of a barrier island well there's the ocean beach which you're probably most familiar with that is on the side closest to the ocean that's where there's a lot of recreation a lot of times they can be um uh that that ocean beach uh will have a dune uh behind it kind of like a protective dune with dune grasses help keep the sand in place and that's true of um uh oh god the outer banks for example like you have to a lot of times not walk on the grass they build like stairs so you go over the dune and not affect the dune at all because it kind of stabilizes the the ocean beach during stormy times um and then behind the dunes you'll have a barrier flat kind of a grassy area that will form and then behind this where the closer to the lagoon you'll have salt marshes um and this um there's two types there's low marsh and high marsh the low marsh extends from uh average sea level to the neap tide line and the high marsh extends to the highest spring tide line i got a picture don't worry um uh so here's a cross section of a barrier island and bear islands are actually in motion they move because they're just made up of sand they kind of get worked by the ocean over and over again and over time because of rising sea levels they're kind of migrating towards the coastline and the reason why we know this one is we've been able to track this over you know aerial photography for decades but two what typically happens so here's your ocean beach here here's your dune right your barrier flat right behind that and then this is yours your salt high marsh and your salt low marsh and then here's your lagoon right and here's the mainland um in the lagoon areas and the salt marsh areas those are highly productive areas i don't know if you go back there a lot of times you go to the bay side of a barrier island it always smells kind of like fishy and gunky that's because there's a lot of biological activity occurring there a lot of plants like living dying things being buried in the lagoon and that leaves what we call peat deposits organic rich deposits so peat beds which are right here and those form in the lagoon and so what happens is as the barrier island slowly gets pushed back towards the mainland a lot of times those peat deposits can start eroding and showing up on the ocean beach in the front side of the barrier island which isn't good because then it kind of i mean it makes the water kind of filled with organic rich gunky material so not very pleasant uh for people who are trying to enjoy a a beach a recreational beach so that's that's why there's a big effort in moving a lot of sand that has eroded away to the front of the ocean beach but it cuts a lot costs a lot of money okay another feature that we find in depositional shorelines are deltas and deltas are deposits that form when rivers just barf all the sediment out into the open ocean here's the biggest river delta united states this is the mississippi river delta this is the bird's foot delta a portion of the delta that's dumping a lot of sediment from the midwest that's eroding away and being pushed into the gulf of mexico it gets its name because it looks like a bird foot right and so here here is the satellite image you can see a lot of suspended sediment uh in the ocean and so uh the way it forms essentially is as as the sediment is like a conveyor belt and bring the river brings a lot of sediment to this area as soon as it hits the open ocean the velocity of the river drops and then the sediment load drops and so it drops and deposits sediment here but if it does that for long enough it'll choke uh the the this portion of the river and then the river will find a new pathway into the ocean and that becomes a new distributary those are just branching channels that carry sediment to the ocean and so that's why when you look at a river delta like this you can see that there's a bunch of distributaries or branching channels that lead to the ocean so you're delivering sediment to a number of different areas and so these are land landform features and they start getting populated by salt tolerant plant species and and and yeah and grows over time um other deltas uh so the mississippi delta is an example of a delta where it's actually growing like sediment being deposited in the ocean is actually occurring faster than um then it being kind of worked by the longshore current of the ocean and being pushed around by that sediment um whereas the nile river delta which is in uh in egypt okay so there's a north flowing river dumps out into the mediterranean sea they have this delta doesn't form like the bird's foot delta it's more of a like a smooth coastline and the reason is because the sediment that's delivered from the nile river gets dispersed and moved quickly by the longshore current it's not enough sediment that's reaching the the river delta and the reason for that is because um a number of areas on the nile river have been uh damned and so they've uh they've impeded the flow of sediment or the natural flow of sediment into the mediterranean so that's why the nile delta looks a little different in fact it's actually currently eroding okay in california all right this is a california-centric book but in california they have this thing called the beach compartments and in areas in california there are three major components these compartments there are rivers number one rivers supply sediment to the beach um then there's the beach itself where all that sediment accumulates to form like a berm right but then there's the ocean working that beach and and kind of stealing that sediment along the longshore current and then it delivers that sediment to these offshore submarine canyons in deeper water and that's the natural process of how sand is kind of transported along the coastline in california now the problem is a lot of the rivers that deliver sediment in california have been dammed up to create reservoirs or diverted you know for agricultural use and for just municipal water use but so what that creates is a problem we call speech starvation and so that blocks the supply of sand to these beach compartments okay so here's an example of one here santa barbara this is considered one beach compartment here okay so the rivers deliver sand here and then the sand kind of moves along the coastline here and then it comes out to these deeper submarine canyons that are a little bit offshore then there's the santa monica beach compartment here's the san pedro beach compartment and then this is the oceanside one okay but ultimately what happens is you can see here here's a cross-section of those deep really deep submarine canyons where the sediment eventually goes okay so the longshore current carries that sediment along the beach and then down these canyons so what happens is if you stop the supply of sediment coming into these beach compartments then these berms will become sand starved and they'll actually see [Music] normal erosion rates it's just you've kind of removed the sand that's going into that area and so the beach will be in decline and so sometimes you kind of lose the beach itself which is which is a shame and so that's a problem they're dealing with in los angeles okay so at emerging shorelines these are areas where you have shoreline shorelines above current sea level okay and that creates those marine terrorists as we kind of talked about those flat platforms that are backed by cliffs and that leaves behind these kind of stranded beach deposits and that indicates that the shoreline uh has risen above uh mean sea level okay um submerging shorelines on the other hand this is where shoreline is at or below currency level and what you have here are drowned beaches uh dune topography lots of sand long shore bars in fact if you go snorkeling in south florida i used to also live in south florida you can go snorkeling and see three different longshore sand bars and when you get off the coast just about almost half a mile off the coast you can see those long bars and there are some coral reefs that form especially at the third bar and then what you see here as well during shorelines where sea levels kind of rising uh really quickly is um the inundation of the continental margin and river valleys that were once river valleys in geologic past but are now drowned and there are estuaries now okay so here's the example of an emerging shoreline so the whole land area is being uplifted and then you're left with these stepwise kind of former wave cut benches that are now marine terraces and here's that the active wave cut bench and then these will be the the next step as this area continues to be uplifted and so sea level as as maybe as mentioned before but sea level uh rises and falls in geologic time and sea level has been 600 feet higher than it is today which means all of florida would be completely submerged under the ocean in fact um in geologic history uh the state of florida or the land area that makes up the state of florida today has mostly been uh under the ocean all right over the past you know 200 million years since the breakup of pangaea but there and sea level has also been 400 feet lower than it is today so sea level it fluctuates in geologic time goes up and down and the reason there are two major reasons for changes in sea level one is when you have an increase in um uh new ocean crust being created so meaning those mid-ocean ridges are really active and they're creating crust at a really fast rate that makes those mid-ocean ridges kind of swell upwards and so what that does is that decreases the size of the ocean basin and so then all the uh when you decrease the size of the ocean basin then that water kind of floods the continents okay so that's one reason and there has been a adjustments in plate creation in in the geologic past where there have been times when uh plates have been created at a faster rate making the ocean basins kind of smaller and pushing that water on onto land it's kind of like if you have a bathtub and you fill it with a certain amount of water and then you change the shape of the bathtub right if you if you if you make the bottom higher that's going to push water above the rim of the bathtub and starts pilling on your bathroom floor okay yeah this causes worldwide changes in sea level okay um and that's those are tectonic movements and and we see this uh ultimately in places like the pacific coast where areas are actively being uplifted okay another way sea level uh can can change over geologic time is uh when we go for with major climatic changes like when we go from an ice age to an interglacial period um you can see wild swings in uh in sea level okay another way sea level can appear to change at least locally is through what we refer to as isostatic adjustments okay what this essentially means is here you have just regular you know earth's crust continental crust and mantle but during colder times in earth's history we may have had giant glaciers sitting on top of the land itself and the weight of this ice some of this these continental glaciers can be like four miles thick you know that's a lot of heavy ice sitting on top of the land and it causes the land to subside or sink a little bit and so what happens is when that ice age is over the um the the the ice all melts away and the land will uplift or rebound to its former position it's kind of like if you had a container ship you ever seen those huge ships at ports that fit those like 40-foot containers in them they got your nikes that are coming in from asia or something um imagine an empty cargo a cargo ship like that or shipping vessel and then it starts getting loaded with those containers like hundreds of those 40-foot containers the boat itself because of all the added weight will sink into the ocean water in in the port right and if you remove that material then the boat will kind of float upwards as you remove that weight the same thing happens with continental crust if you put a lot of weight on it over long periods of geologic time it'll subside and once that weight's removed it'll uplift and this is currently happening in norway for example norway during the last glacial maximum about 18 000 years ago was covered in glaciers covered in huge wall you know heavy continental glaciers and ice caps and all that weight pushed the weight downwards but today a lot of norway's is not covered by glaciers and exposed so our ocean sea level is rising today right but in norway they're locally seeing sea level fall because the rate of crustal rebound is faster than the rate of sea level rise which is pretty crazy so everywhere else like here in florida we're experiencing sea level rise okay so those are eustatic sea level changes and those occur worldwide okay so here are the different sea levels can rise another way by destruction of inland lakes so a lot of times those are also associated with ice ages because you have huge carnival glaciers that create uh inland lakes giant lakes and when those glaciers kind of melt away then a huge pouring of water can go into the ocean we talked about seafloor spreading rates already changing the size of the bathtub as an example and then here formation or melting of glaciers this is the the changing of uh earth's climate all right when we're in an interglacial period like we are now major ice caps and continental glaciers and alpine glaciers they're melting and all that water is going into the ocean as a result sea level will rise and in addition to that in a warming interglacial period the oceans get warmer and when water gets warmer it thermally expands and so if the oceans are warmer they're going to thermally expand and also cover more of the continental margin it's kind of like when you have like a you heat up a cup of soup in the microwave and you leave it in too long it'll flow over that water line because the the volume of that water expands as you heat it okay so um the pleistocene epoch which began about two million years ago and ended 10 000 years ago we often call it the time of many ice ages there are about four ice ages that affected uh that time period almost in the order of every 100 000 years where we would go from an ice age to an interglacial period and so during those changes from an ice age to an interglacial period sea level rises and falls sea level was about 400 feet below today's sea level change 18 000 years ago okay that was the last glacial maximum so just to put that in perspective like um today's tampa and st petersburg florida would like double in size if sea level fell about 400 feet and saint petersburg and tampa would be about 150 miles from the west coast coastline back in that time okay so florida would essentially double in size the tampa area would be considered central florida okay and on the flip side if we go to an all-out interglacial period and earth's climate warms significantly if all the remaining ice on earth melted today meaning all the ice in antarctica greenland those ice caps and all the glaciers sea level would rise another 230 feet okay that's that's incredible um the highest elevation that i know of i think is sugarloaf mountain in florida just like a big sandy berm that's in central florida i think that's at an elevation of 300 feet so practically all of florida would be underneath the ocean if that were to happen if all the ice on earth were to melt and go back into the oceans okay so yeah check this out this is sea level over the past almost forty thousand years before present so this is present right zero thousand years ago okay and then over here is about forty thousand years ago okay so our last glacial maximum was about 18 000 years ago all rights which was right here so this was 40 000 years ago we had glaciation or things got much colder a lot of water was being removed from the ocean and snowing on land and becoming part of the glacial cycle so a lot of water was being evaporated from the ocean being stored on land and that lowered sea level to the point where let's see if we draw a line shrouded here um sea level was almost 120 meters lower than it is today because it's not really a straight line uh but that's 400 feet so 18 000 years ago right around here 18 000 years ago sea level was 400 feet below its present value okay so over the past 18 000 years as we've warmed all that water that was locked up in glaciers and ice caps has been going back into the ocean and sea level has been rising to it to its present day location okay so how do we uh you know slow down the rising seas of the ocean well humans build hard stabilization features or structures to reduce coastal erosion it's also called armoring the shore but a lot of times uh sometimes like humans like when they try to do something they oftentimes make it worse which is the case with a lot of heart stabilization features uh one which i'm sure you've seen often is called the groin a groin is just basically a pile of rocks that is put into an area uh and it's perpendicular to the coastline okay so what happens is it interferes with the longshore current right here's the zigzag motion of the sand and here's the direction of the longshore current so what happens is the longshore current runs into the groin okay and the water velocity diminishes as a result and all the sand deposits so what you see is here's the original coastline what you see is an additional deposit of sand over here which seems like it's great especially if your house is right here you're like yeah i got a bigger beach right but the problem is on the other side of the growing you see increased erosion so this here is the former shoreline okay and then it's changed all the sand has been uh essentially eroded away because it's not uh like this sand is no longer able to deposit over here so groins don't really add sand to the beach they just kind of create winners and losers okay so there's four major types of stabilization structures uh groins that i mentioned groin fields are just a bunch of groins jetties are this are really the same thing they just kind of they're two groins parallel to one another and they usually block open like an inlet so we can have boats come in and out break waters are parallel uh to the shoreline i have pictures and sea walls are just straight up built right in front of the beach and they typically protect homes or businesses all right here's a groin field all right so here just have a bunch of different groins on this barrier island okay and so if you notice you see how there's sand building up over here and then there's a diminished uh or erosion of sand on this side so you can tell just by where the sand is depositing the longshore currents moving in that direction okay so sand is just essentially distributed differently uh but no new sand is added to the beach so let's show some more examples of this here are jetties right so we like to have harbors so we can park our expensive boats i don't have a boat i don't have enough money but anyways um yeah so this protects it from the wave activity that's in the open ocean so that's why we have it and it gives you easy access to the open ocean that's nice so here are those jetties and what do you notice about the sand build up here look at this beach it's absolutely amazing and huge these people are probably really happy about it but over here you actually see erosion of the beach and so these people aren't very happy and you can tell the longshore current is in this direction so jetties are built in pairs like the new smyrna beach there's an inlet there a lot of surfers like to ride those wedge waves there so here's just a reiteration of where sand is deposited on jetties and where they're eroded average long shore drift in this direction you get that position here erosion here and deposition here you're just essentially creating winners and losers and that's why it can be kind of a big uh fight amongst coastal communities and where these things get built okay breakwaters are built parallel to the shoreline so the shoreline's like over here if you notice see the wave activity is diminished over here you see choppy stuff so people will park their boats back here and so uh the problem with breakwaters and you'll see in this picture here is santa monica california this is before they built the breakwater so here's a santa monica pier okay here's the long shore current here behind directly behind the breakwater which is right here you'll see a big deposition of sand and then but the thing is beyond the break water then you see additional erosion over here so again you're just you're not really adding any sand to the beach you're just widening the beach and diminishing the beach on the other side so break waters have a similar effect to groins into uh jetties sea walls on the other hand they're these are the worst of the worst because these they typically built these giant sea walls right in front of a um either they build in on a barrier island or uh they'll build them on uh like a where the coastal cliff is and it's designed to armor the coastline and protect it especially human developments like our homes or businesses or any communities that are close to the water like this but the problem is is that then it the because there's a wall there it concentrates the entire uh ocean energy the wave energy towards the sand on the beach so it can take one storm and remove all the sand on the beach okay and eventually you lose with 10 000 waves crashing in a 24 hour period over years that wave activity will undermine the integrity of the sea wall and will begin to collapse you start seeing issues like this right nature eventually always wins right you get a rusting rebar and then what you'll have is a collapsing sea wall and that could undermine the structures here and notice there's a lot of loss of beach sand over here so generally not a great idea it's it's better to leave these coastal areas kind of to their own devices let them kind of change over time on their own so there are alternatives the hard stabilization there are um construction restrictions hey don't build on barrier islands right then there's beach replenishment that's really popular in florida a lot of our tax money especially sales tax that goes to paying for areas or paying for companies to dump sand on our beach fronts that happens in melbourne that happens in fort lauderdale miami a lot of places oh on the keys the keys don't really have any natural uh beach deposits mostly limestone there so if you go to the any of the keys down there and you're on a beach that's fake sand south beach that's sand that's dredged up offshore and placed on the beach um so that's that's beach replenishment and then there's relocation you can actually move buildings away from the coastline uh to save them okay so the simplest alternative is hey how about we don't live uh on barrier islands let's keep those in their natural state and just have them as like we can visit them that would be a good idea limit the building near shorelines but um that's not what that's not what what's happening you know people want to live really close to the beach and enjoy that you know they want that kind of desktop screen saver background as as their reality so they'll pay big bucks to live on the beach and you can see that in the housing prices on the beach uh as a result but i mean people who live near the coast on barrier islands have really high hurricane premiums which is fair because their houses are more likely to get damaged by storm surge and hurricanes because they're on the coast but the national flood insurance program really um doesn't raise the rates too much on people who are who are living close to the to the ocean and are very prone to flooding uh in fact we essentially subsidize uh that stuff and it kind of incentivizes constructing near the ocean all right here's the example of beach replenishment this is miami beach this is this is miami beach in the 80s um the cocaine cowboy days right so sand is added to the beach five to ten dollars per cubic yard look at this there's nothing there right people are like what's going on but here this is all the sand that they've added to uh south beach so they typically dredge it from the offshore uh bars that are um uh you know out there and then they just basically have like pipes that sucks it up and then they just dump it over here so it's pretty expensive and then there's relocation that's physically removing structures and moving them more inland and that allows for more of a natural balance with beach processes okay so now let's shift gears and talk about coastal waters okay up until this point in this class we've really you know when we've talked about ocean circulation and ocean currents and gyres and all that all that stuff we've been talking about ocean open ocean waters coastal waters are really waters that are really close to the continental margins waters where uh humans uh reside more okay that's just just offshore the beast beaches are coastal waters relatively shallow water uh right off the islands and continental shelf broad and shallow okay and in these areas there um are drastic changes or there could be drastic changes in uh some of the variables of the water itself which is not reflected in the open ocean there are changes like salinity temperature and there are also geostrophic currents in coastal areas we'll talk about an example of that all right so salinity in coastal waters varies a lot because coastal waters are affected by a river runoff where a lot of rivers dump out into the ocean that's fresh water fresh water doesn't have a lot of dissolved solids in it so it's low density in comparison to seawater so it doesn't really mix very well with seawater and so what happens or what's created is that you just have like um they're separated those water masses are separated by their uh they're stratified based on their densities so fresh water will sit on top of the seawater but you'll have a well-developed halocline okay remember if you remember peak nucline and halocline this is the spot uh in the water column where there's a drastic increase in increase or decrease in salinity okay so in the example say you have the input of fresh water from runoff or a lot of fresh water coming off of an area a very large river so the coastal waters here will have lower salinity as a result oops yeah red on red doesn't really make sense here all right so let's go purple so this is all fresh water kind of sitting on top of the salty water down below so all this input of fresh runoff lowers the salinity in this upper layer but then once you get to a certain depth salinity increases rapidly okay and then it kind of goes into the average uh salinity in the ocean once you get beyond the halocline in other situations where you have a lot of dry offshore winds right around 30 degrees north or south latitudes horse latitudes there's a lot of evaporation in coastal waters and that can actually cause an increase in salinity in coastal waters so some coastal waters can be actually saltier than the average open ocean numbers so you can have actually uh because of the increased evaporation really salty coastal waters and then as you go in into uh deeper and deeper waters the salinity will decrease until it gets to kind of average salinity values for the open ocean okay and then there are situations where you get a good balance of uh freshwater runoff and also a lot of evaporation and in these areas depending on the geometry of the of the coast uh the tides will help mix this water really well and you get a lot of vertical mixing that the salinity doesn't vary at all so it's isohaline okay so those are some characteristics of coastal waters so temperature in coastal waters can affect whether or not some of these waters mix very well because if you have higher temperature water then that's lower density then you have two water masses and they don't really mix but you can have um a similar situation with salinity and temperature in coastal waters like you can have isothermal water and that's water that's very well mixed throughout the entire water column has the same temperature but you can also have water masses with varying water temperatures and then a thermocline will develop as a result and that's dependent on where you are on earth what latitude and also on seasons i'll show you here but if you if you say you go to really high latitude areas close to land so coastal waters again not in the open ocean in these really high latitudes like in the arctic circle um the temperature of the coastal waters remains uniform okay and so that's very close to freezing about two degrees celsius very low and it's the same on the surface here or on closer to the bottom of the coastal water there we call that isothermal and interestingly enough if you go to closer to the equator at very low latitudes you get the same result but just really high temperatures isothermal really high temperatures and the reason for this is that it's it's really hot there's a lot of good vertical mixing and so the temperature at the surface is very similar to the temperature again and this is shallow water much shallower than in the open ocean but if we go into an in-between latitude say 40 degrees north of the um equator so like right here the coastal waters change depending on the season in the summer the the solar radiation will heat up the upper layer of the coastal waters and make it much warmer okay and then once you go to depth then you then you hit the end of the thermocline and temperatures drop and then they level off to much cooler deeper waters okay and then in the wintertime as shown by this weird winter god blowing cold frost on the surface um you actually you do develop a thermocline but the opposite where you have very cold surface waters and as you go deeper all of a sudden there's a big increase in temperature so in mid-latitudes there is variation depending on seasons there are also on coastal waters there are geostrophic currents so remember from when we were talking about gyres certain portions on the west side of ocean basins have like a hill of water and then as currents approach it they're influenced by the coriolis effect and gravity so that affects those geostrophic currents but these can actually occur in coastal waters and so what happens is a lot of fresh water runs off into the ocean right and this sits on top of the salty water kind of making it a little bit higher and then the coriolis effect will deflect that flow of fresh water and so one cool example of this is the davidson current that's off the coast of washington and oregon i've got a picture coming up but um here in the northern hemisphere as we know the coriolis effect deflects moving masses to the right okay and so on the passer curve northward on the western coast and southward on eastern coasts so davidson currents on the west coast so it's deflected northward so here it is what happens is and this typically um the currents are like this year round the geostrophic currents or the davidson current but during the spring and summer the current's stronger because there's more water being kind of pushed through the river systems and into the ocean so here is that kind of wedge of fresh water that kind of diminishes the further away you go from the continental margin but as the freshwater kind of dumps into the ocean it begins to curve to the right because of the coriolis effect and then that starts david's current northward flowing coastal geostrophic currents and it moves in the opposite direction as the open ocean current the california current remember this current uh is you know uh an open ocean eastern boundary current uh fairly slow in comparison to western boundary currents but still it flows in the opposite direction which makes it kind of an interesting characteristic of uh places in oregon in washington so there are coastal currents like that that vary from open ocean currents all right estuaries estuaries are a partially enclosed coastal body of water where you have fresh water run off from a river kind of diluting the salty ocean water in this kind of marine environment and ph salinity temperature and water levels depend based on how well the river mixes with the ocean water and also the geometry of the enclosed area but of our modern estuaries most of them formed after our last glacial maximum 18 000 years ago and there's four main types of estuaries okay and they all have a geologic origin and i've got pictures so i'll show you but the coastal plain estuaries they form as sea level rises and floods existing river valleys okay so that's when you're approaching like an ice age to an interglacial period so sea levels are really low because of the ice age but because all that all those glaciers are melting sea levels slowly rising and areas that were river valleys um are now being inundated by the ocean those become the new estuaries and the best example of this is the chesapeake bay uh estuary which is part of like the maryland virginia potomac and the susquehanna river dump into those areas okay and so that's the that's the main example i'll show you a picture of what that kind of looks like then there are fjords and fjords form again as sea level rises that floods instead of flooding river valleys it floods valleys that used to be covered by glaciers and when you have a valley that's covered by glaciers they're typically u-shaped okay and it creates for re a really interesting coastline i'll show you some pictures but here are the areas where there are estuaries that are like fjords and it makes sense places that are really high uh either elevation or in latitude canada new zealand chile and norway are areas that have fjord estuaries okay so here's a cross-section of uh a drowned river valley okay so if you can imagine the entire delaware delaware bay the chesapeake bay here these were river valleys like if humans were you know farming 18 000 years ago they would have really nice farms in these river valleys here today they're covered by the atlantic ocean so these are the um those are the uh drowned river valley estuaries okay here are the fjords okay fjords are typically u-shaped okay um and then this is where the glacier used to kind of carve through this river valley and that's why it creates that kind of broad u-shape what's cool about fjords is a lot of times they'll have these hanging valleys close to them so today in norway you can stand on a really steep sided cliff that looks over a marine estuary from a really high height and they have really steep areas i think in the book they have a really cool picture of one the next type of estuary is called a bar built estuary and this is what we're familiar with in florida there's they're essentially um barrier islands that are separated by the ocean uh with a lagoon and uh sand that's deposited and reworked by wave action so there are barrier islands lagoons much of the gulf coast and the east coast are examples of this right here which is the bar built estuary so we have sand bars essentially building up these areas barrier islands and lagoons and then finally we have a tectonic estuary and these are where you have faulting and folding of rocks which creates a down dropped area so this area here is down dropped because of the upward motion of this block and the upward motion of this block where this block is moving downwards which creates a depression and that is a tectonic estuary because they're essentially built by the tectonic processes of an active continental margin so the best example of this is that the san francisco bay would be a tectonic estuary in fact in the last image i show you that is the picture of the san francisco bay all right so those are the four different types of estuaries so the way water mixes in estuaries there's a a number of different examples um a vertically mixed one is one where uh you have very low volume of water going into the estuary so there's a net flow from the head to the mouth of the estuary and so you get very well mixed water fresh water and salt water together there's slightly stratified and highly stratified and this is where you have salinity increases from the head of the estuary to the mouth in two distinct layers so these are you know fresh water and salt water that are distinguishable based on uh uh density so the fresh water will sit on top of it and then finally there's a salt wedge estuary where um a wedge of salty water from the ocean kind of moves underneath the river i've got pictures let me just show you so here is the vertically mixed estuary here this is typically these estuaries are um like this when you have um very well mixed water okay so good vertical mixing uh aided by tides and stuff like that and not a lot of incoming fresh water enough to like inundate and create stratifications here's the slightly stratified one and here's the highly stratified if you notice a stratified one here's that wedge of fresh water and it um it the change in salinity is rapid okay you can see that and then here is this is the salt wedge so there's a huge wedge of salty water that kind of pushes itself underneath the fresh water so that's how kind of estuaries mix with uh in terms of fresh and salt water so estuaries are these areas are threatened because our human populations are close to the coastlines a lot of the estuaries like the caloosahatchee area or the indian river lagoon on the east coast of florida their effect a lot of people will complain uh once we start releasing water from lake okeechobee it's a lot of that water with the like blue green algae that's really nutrient rich that really messes up the estuaries and can cause uh um you know fish kills and you know it's really smelly and gunky water low oxygen levels so um people don't like that but the problem is is that we're building around these uh coastal areas so much and we have a lot of agriculture there that it the waterways often become polluted with synthetic fertilizers that and pollutants and sewage that goes into the water and that contributes to these algal blooms so it's a big problem especially here in florida estuaries are important because there are breeding grounds for a lot of marine animals they're the nurseries for a lot of benthic organisms and a lot of organisms that that are from the open ocean or commercially fished organisms and and we can damage these environments pretty easily just just by over developing all right one example of uh kind of an area that's gone really downhill especially because these are just heavily populated areas is the chesapeake bay that's a slightly stratified estuary a drowned river mouth and so there are huge seasonal changes in salinity temperature and dissolved oxygen dissolved oxygen is how much water is i mean how much air dissolved air there is in the water which fish need to breathe and also benthic organisms like crabs and oysters um so as the fish swims through the water they're using up that dissolved oxygen that's how they live right um so what happens is a lot of times in the in the spring you get a lot of water flow into the chesapeake bay because the susquehanna river the potomac which is over here that dumps into these areas but that goes through a lot of farmland a lot of urban areas so a lot of contaminants and fertilizers can get in the water and that causes what we refer to as anoxic waters okay and so the waters especially in the deeper areas they can become oxygen depleted and the reason they become oxygen depleted is because when you have sewage and fertilizers those are a lot of times those are like like that feeds algal blooms and white why that might seem kind of good like oh my god an algal bloom that means things are going to be eating the algae in a kind of cascade of life and stuff like that no the problem is is that if it's uncontrolled especially with chemical fertilizers you get huge algal blooms right and there they proliferate so quickly and so when they die the bacteria uses up all the available dissolved oxygen in the water to decompose the algal blooms and that diminishes the the available oxygen dissolved oxygen content in the water and then the the fish the crabs in the chesapeake bay the i think they're the blue crabs they're the the commercially yeah blue crabs and oysters those bottom dwelling organisms will die out and that's significantly harmed the uh you know the seafood economy in those areas i don't know if you've ever been to baltimore you can have those crab cakes they're unbelievable but anyways so this causes this harmful algal blooms and that continues to be a really uh hot environmental issue especially here in florida too because we've got those uh a lot of the uh really enriched um polluted waters from lake okeechobee being occasionally released um into the caloosahatchee and the st lucy in indian river lagoon areas all right speaking of lagoons these are shallow water bodies of brackish water that are landward of barrier islands so they're behind barrier islands so this would be a barrier island here so that re that restricts the circulation with the ocean and so that creates three zones fresh water zone transitional zone and salt water zone so as you approach the mouth of a lagoon that's the saltwater zone this would be the intermediate or transition zone and then this would be the freshwater zone and then also um this would be typical of florida right rainy and dry season we're approaching the dry season it's november so we would have changes in the salinity level so because there's less precipitation and there's more evaporation and there's less incoming river water then the salinity rates increase in all three zones more so in the mouth because you have a bigger influence of ocean water coming in with the tides in the rainy season then the salinity gets suppressed right which makes sense and then here's the tidal range really the tidal range is only affected in the mouth of the lagoon which is right here but these are interesting environments because uh they you have a lot of salt tolerant marine organisms and plant organisms that live in these areas and refer to those as wetlands those are ecosystems where the water table is very close to the surface and the ground is typically saturated with water okay and that water can either be you know it can be um uh coastal or brackish water or even fresh water okay and so coastal wetlands occur along the margins of coastal waters estuaries lagoons marginal seas and they include swamps tidal flats coastal marshes and bay use okay all right the first type of coastal wetland is called the salt marsh you might not be as familiar with these because these occur a little further north than where we are between 30 and 65 degrees latitude north and south of the equator and so what they salt marshes essentially they they support salt tolerant grasses and other halophytic low-lying plants those are just salt salt-tolerant plants the fancy word for that and they occur along many many coastlines a lot of them deal with the salt in in different ways for example some of them get rid of excess salt by producing salt crystals on their leaves okay some of them accumulate salt in their tissues and dispose of it by breaking those tissues off into the water itself all right so those this is here's a typical saltwater marsh in morro bay california so it's a flat lying area great stopping point for a lot of migrating birds okay then there are mangroves you might be more familiar with this we have this in florida mangrove swamps are really restricted to tropical regions so below 30 degrees latitude and towards the equator here you find salt tolerant mangrove trees that kind of grow their roots downwards into the mud or sediment you have shrubs palms and they form like that tripod type root system which is uh fairly typical in the book they've got some really nice images of of the root systems from mangrove trees kind of coming downwards and in into these kind of brackish and salty uh environments so you find them in the caribbean florida and most extensively in southeast asia let's see we got a picture here so anything that's in brown would be a salt marsh so we see that on the east coast the united states and gulf coast and also pacific coast and then once you get down to lower latitudes then you start running into the mangroves that's caribbean yucatan west coast of central america and mexico and again in in this portion in southeast asia we see a lot of mangroves over here so coastal wetlands are very important they're a home to a very diverse assortment of plants and animals and they're very productive ecosystems they're the most productive on earth and when they're kind of left undisturbed they provide a lot of economic benefits that we don't really give them credit for salt marshes as an example they serve as nurseries for almost half of the species of commercially important fishes in the southeastern united states so a lot of the fish that we depend on to commercially fish they get their starting points at those salt marshes okay so some of those include oysters scallops clams eels and smelt those come from marshes for mangrove ecosystems these are also wetlands they're they're kind of nurseries for very commercially valuable shrimp prawn shellfish and many other species and these wetland areas are also really great stopping or stop over points uh for migrating uh birds that are going into different you know when they're they come down for winter they go north for summer whatever it is their migrating pattern is these wetlands are great areas for them to stop over rest get a bite to eat or something like that in addition to that if you ever go to any of the mangroves a lot of them will be places where a lot of birds nest certain times of years so so that's that's really important as well in addition to that coastal wetlands they soak up a lot of nutrients that run off of farmlands and also from rivers so they soak up all because they're so productive they soak up all that stuff before they get into coastal waters and to coastal estuaries and those pollutants and nutrients that's what fuels those harmful algal blooms and creates those oxygen free dead zones that we were talking about earlier so amazingly wetlands are kind of like akin to are kidneys they're like nature's kidneys so wetlands can filter out kind of polluted nutrient-rich water before it goes out into the ocean which is really good in addition to that a lot of wetlands they protect the inland areas of the united states from erosion from wave activity those you know tripod like roots that just go directly into these the mud and sediment in these kind of coastal areas really diminish the wave activity of incoming storms and stuff like that which are really valuable at protecting inland areas so they dissipate a lot of coastal wave energy and they also prevent flooding from storm surges because they can absorb a lot of that excess water so wetlands are are very important um and we're just starting to realize that now sadly though uh more than half of the us wetlands have vanished right we've filled and developed them put up uh cookie cutter homes and houses and stuff like that i mean we have to live somewhere right but maybe not destroying wetlands would probably be a good idea um because it just provides so many valuable resources to the area surrounding it as well as marine life and bird life and stuff like that the epa is actually since 1986 they established an office of the wetlands protection program and that helped slow down the destruction of wetlands and new areas have become like water conservation areas to help with the cleansing of water before they go out into the ocean uh but but still we're developing we're growing as a population so quickly and in addition to that sea level uh is rising so we're expecting further wetland loss uh which is uh which is bad right and here's just a visual of um how much wetland land we've lost uh you know over since this this is the uh uh the air the continental united states um un you know undisturbed wetlands we had about 87 million hectares and then through human activities only about 106 million acres are left so um uh we're kind of the bad guys here we're the ones kind of clearing out uh the natural coastal environment because we want to live closer to the to the ocean but but there are movements to kind of restore and conserve the wetland areas because it is for our own good so there is some light at the end of the tunnel there all right thanks for sticking with me for an hour and a half maybe you broke that up but um yeah cheers