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The Decline of Seagrass Meadows

Zostera! Eelgrass, Zostera marina, is a flowering, marine vascular plant that remains submerged all the time. This is quite a feat for vascular flowering plants, and only a few dozen species world wide are capable of growing completely submerged in a marine environment. Eelgrass creates and extremely important habitat, its upright structures and complex root system create a 3-D living space for many different types of animals. It is (or was) the dominant habitat forming SAV (submerged aquatic vegetation) throughout much of the coastal waters in the northeastern United States. Unfortunately, for various reasons, eelgrass meadows have seen drastic declines, and in many locations eelgrass only exists in a mosaic of small patches. This is extremely bad news as many of the important, and formerly important, commercial and recreational fisheries of the northeast US are dependent on Zostera at some part of their life cycle as a nursery and foraging ground. Some of the species are finfish like tautog, bluefish, fluke, winter flounder, porgies, while others are shellfish such as blue mussels, hard clams, oysters, bay scallops, and blue crabs. Many of the aforementioned species support or once supported vibrant fisheries. Many of those fisheries have collapsed, also for various reasons. However, is it possible there is a link between the crash of the fisheries, the decline of Zostera and the failure for recovery on both ends?

Bay Scallop on Eelgrass

Argopecten on Zostera! Bay Scallops, Argopecten irradians , have developed a very close relationship with eelgrass, Zostera marina. As larvae, they are passively transported, and tend to settle in eelgrass meadows when the current is dampened by the 3D structure of the seagrass. This same 3D structure provides post-set juvenile scallops a spatial refuge from predation. Even as larger juveniles and adults, scallops are capable of, and have been shown to, actively select eelgrass habitats.

Other species also use eelgrass

grass shrimp A number of other species utilize eelgrass as a habitat. Included are grass shrimp, like the Palaemonetes pugio, other decapods such as blue crabs, bivalves such as hard clams, gastropods (snails), and numerous fish species, including winter flounder, tautog and cod.

This Jamaica thing is rough! (Not really)

So we have been extremely busy since we arrived.  We have essentially crammed a coral reef ecology class into 4 days, which was overwhelming for the students.  Their practical exam is this afternoon, so they are all cramming and freaking out a little bit.  I have tried to quell some of their anxiety, but at least by this evening, the lecture and exam portion of their class will be over.  In between lectures, we have been snorkeling, and today I did my first dives since arriving.  So that’s good.  The students will start their projects tomorrow, and have ~1.5 weeks to conduct a research project.  The weather (wind) hasn’t been very good, so hopefully we get more dive opportunities, but the lagoon has been pretty cool.

Some things I’ve seen:

Red Mangrove

Sharptail eel

More photos to come, but internet here is incredibly slow so I am having a hard time uploading. But, you should check out the student run blog to see what they have been seeing/doing as well.

 

 

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