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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.

Shrimp, anyone?

There is some speculation about the FDA’s standards for Gulf seafood. Granted, I know the government wants to do everything it can to restore the economy to this oil-ravaged region. According to some recent posts, the FDA may be allowing higher PAH levels in shrimp, crabs and oysters sold for consumption, because they assume that most people in the US don’t eat very much seafood in a month, and that the majority eat significantly more finfish than shellfish. It appears as though the new concentrations for BaPe for shellfish in the Gulf is 3x higher than the levels allowed in other recent oil spills. In addition, some lab testing not done by the FDA suggest that the levels of PAH in the shellfish is much higher than this allowable limit. Of course, this calls to questions differences in methods for testing, but there might be some cause for concern here. We all heard about the sniff test method.

It speaks volumes when even the fisherman are questioning the reopening of the Gulf fisheries. Sure, we all like a shrimp cocktail now and then, but is it possible the FDA, under pressure from state and federal government, lowered safety standards to try to bring some revenue back into this part of the country? I’d like to think things don’t work that way, but I don’t know. I will look for a more reputable source for this news, but when I saw this, I thought it might be worth mentioning.

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