Zostera marina is a seagrass species, commonly known as eelgrass, that is found on both coasts of the United States, as well as in Europe. Unfortunately, Zostera is disappearing all over the place, including right here in New York. This could have devastating impacts on animals that rely on eelgrass as foraging grounds, or, as is the case with scallops, use it as a refuge from predation. This is its story, as seen through the eyes of an aspiring graduate student...
So we went through my suction samples yesterday, and I found 3 juvenile scallops in total... Nothing spectacular, but it does mean that there was some natural recruitment, which is exciting... Another interesting thing, which was expected, was that the star shaped patches (the patches with the most perimeter) had higher amounts of drift algae and larger numbers of predators, although I haven't run any tests for significance yet... This is good news though, supports the edge effect theory...
Well, I took my grass mats out of the water last week. Not only did I remove my scallops, I suction dredged the mats and took them out as well. I haven't finished measuring the scallops or measured the dry weights, but soon I hope to have those results worked out. Tomorrow I am going to finally go through the suction samples and next week I am going to visually inspect the mats to see if I missed any juvenile scallops, predators, etc and then stow them for next year. One exciting thing I did notice though, while shucking my scallops I noticed that many of them still had gonads. Usually the gonads are spent this time of year, but for many of my scallops, they were not. This might be due to water temperatures still being so warm, or may be mere coincidence. Whatever the case, this supports the idea that there is a late fall spawn for bay scallops in Long Island. I will update once I have the data!
Well, I realize that I started this blog and never put any updates into it... Oops... It has been a busy summer filled with long days on and in the water, but with some excitement as well... I finally put my artificial seagrass mats out in the field in July, which was a very exciting day... The idea behind the artificial mats is that the local estuarine habitats are changing from once dense meadows of eelgrass to small isolated patches... Nobody is really sure the impacts of this changing habitat, and rather than disturb the already stressed existing eelgrass, we chose to make our own artificial mats... This also allows us to make them all the same, in terms of number of shoots, blades, etc :
Once they were in the water, they looked great... The ribbons stood upright... They were quickly colonized by small fish like silversides and killifish... Soon the mats were colonized by other fish, like pipefifh, tautogs, cunner, and even some small flounder and sea bass, and many invertebrates, including grass shrimp, mud crabs, spider crabs, blue crabs and whelks... The mats also experienced epiphytic algal and bacterial growth and also received a fair amount of drift algae... All in all, it was very impressive and far exceeding my expectations:
I placed scallops out in these mats, 10 to a bag, to prevent predation, in order to measure scallop growth... They have been growing well, around 25 millimeters (around one inch) in 8 weeks time... These are about triple the size of when I put them in (averaging around 11-12 mm, and now between 35-40mm)... These are very exciting results, although I don't have pictures right now to show... I attempted a predation experiment with tethers, however, this wasn't very successful, as I had extremely high mortality that I could not attribute to predation...
I have also worked on spat collectors located in various locations throughout the Peconic Estuary, with some fairly exciting results... This is part of a large bay scallop restoration effort undertaken by Suffolk County and the Cornell Cooperative Extension of Suffolk County... This effort includes researches from various parts of Long Island, as well as dozens of local volunteers, to spawn scallops in captivity, grow them out in field settings and hang millions of them in lantern nets in close proximity in the hopes that having that many close together will enable them to spawn in the wild and allow larvae to recruit throughout the bays... This is the first full year with the high density of scallops in these lantern nets, although various other spawner sanctuaries have been set up for the past few years... All the data is still coming in, so nothing concrete yet, but there are some real positive signs that this type of method might be working... Finally, I am also investigating the effectiveness of alternative habitats... I have looked at free planted and tethered scallops in alternative habitats for the past 2 summer seasons... Stay tuned for the results...
I am a marine biologist that is currently attending graduate school at the School of Marine and Atmospheric Sciences, Marine Sciences Research Center, of Stony Brook University, New York. I am very interested in marine ecology and have been focusing my studies on bay scallop interactions with their habitats. I plan to investigate various anthropogenic impacts on bay scallop populations for my PhD dissertation. This blog will highlight the details of my graduate research, from bay scallop-eelgrass interactions as previously mentioned, to alternative habitats for scallops, such as Codium, to trophic cascades, and more. Enjoy!
Eelgrass is an important habitat for multiple marine species, including the bay scallop
Scallop on Artificial Eelgrass
This tethered juvenile bay scallop attached itself to my artificial eelgrass...
The decline of eelgrass meadows
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?
Eelgrass, Zostera marina, a temperate seagrass species, providing a vital habitat for numerous marine species
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Scallops in eelgrass
Some adult bay scallops we planted in eelgrass for a free release survival experiment we conducted
If you live in coastal zones, urge your local and state representatives to push for environmental issues that you are concerned about. Ask for more stringent rules regarding the destruction of existing eelgrass. Encourage restoration programs to be set-up. Call your state and national representatives and ask them what they are doing to protect our precious resources. Practice safer boating and know the undersea terrain - i.e., don't drive your boat in very shallow water. Avoid clamming in eelgrass meadows.