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...
Adult bay scallop in a Codium fragile bed Well, there were certainly a lot of bubbles yesterday. I went diving, but in addition to the normal exhalent bubbles from every breath, my Air2 was leaking, creating more bubbles and increasing my apparent air intake. But that didn't stop me from doing my transect surveys at 5 sites in the Peconics. We stopped all around Northwest Harbor (East Hampton, NY) and Sag Harbor, and then 1 dive in Southold Bay. While we didn't see as many scallops as we would have liked, we did see a few, which was good. In most places, we saw more seed A seed bay scallop in Codium A bay scallop "smiling" for the camera... Old Blue eyes A seed bay scallop, note the darker mantle than the one above than adults, An adult bay scallop with its epiphytic and epizooic growth which is good and bad. It is good in that hopefully there are enough seed to survive over the winter and spawn next year. It is bad for the commercial and recreational guys that there aren't enough adult scallops (potentially) to go around. Who knows how this year ends up. However, I did see a decent number of scallops, small fish, hermit crabs, spider crabs, mud crabs, grass shrimp, whelks, your usual suspects. A nice day diving, although cold (12.5C). Its about time to break out my drysuit. The visibility and diving this time of the year is the best though, so I won't complain. Going again on Friday. Stay tuned.
Or something like that... Last Thursday, October 16th, I went diving out in Flanders Bay. We were doing a bottom survey of a previous free release spot for scallops, since we were preparing to release ~100,000 seed scallops as part of the restoration efforts going on in Long Island. Flanders for a very long time sustained a sizeable scallop population even inthe absence of eelgrass (Zostera marina). But land use changes in addition to the brown tides more than likely led to their demise in that area. Luckily, a year after last years plantings, there were still ~ 1 per square meter, much lower than stocking, but still a decent number. After surveys, we set up an area to plant new scallops, at ~ 100 per square meter. We hope to dive on the site once more before it gets too cold, and then start again in the spring. Hopefully this will help jump-start a population in Flanders. Additionally, I saw some really cool things... including a porgy trying to eat leftovers from a whelk feeding, a whelk eating a newly planted scallop, and a large northern puffer, which are rare nowadays due to overfishing. Oh and this mean looking guy. And tons of cool shells. All in all, it was a pretty cool day of diving. Not only was I a part of the free release, I was able to see some cool things, like direct predation, swimming scallops (which are impossible to get a photo of, in case you were wondering why there isn't one) and that puffer really made my day.
Yes, that is right. Failure. I guess it happens to everyone, and I half expected it by the way my recruitment experiment was going all summer. But I did get that glimmer of hope 6 weeks ago, when I did find a handful of scallop spat on my recruitment squares, and both 4 weeks ago and last week when I saw numerous scallops in our local spat collectors. Alas, no recruits on my squares. That old adage of "If you build it, they will come" does not seem to be ringing true for scallop spat in my grass mats. Now, I don't want to make this all bad, because clearly highly mobile macrofauna have had no problems discovering or inhabiting my artificial grass mats. In fact, with the water relatively clear last week, I saw numerous species, including tomcod (which I had not seen in Hallock in all my dives there), largish sea bass, and the usual suspects (killifish, pipefish, sticklebacks, cunner, blackfish, porgies). So the whole "if you build it, they will come" theory behind creating artificial habitats or restoring habitats may ring true for certain mobile organisms. However, habitat value aside, no habitat can encourage organsisms to come if those organisms can not get there. Simple. If the supply is low, which I have reason to expect that it is (judging by the almost complete absence of adult scallops from the bay, among other things), it cannot be compensated by available habitat. However, it is still quite possible that I am simply missing the spat on my collecters, since collecting approximately 1 square meters worth of recruitment squares (~500 shoots) out of ~119 square meters of areas (~59000 shoots) may just be too small an amount to see anything. Finding scallop spat on natural grass is akin to finding a needle in a haystack, so why would my mats have been any different? And yes, the number of squares I collect seems low relative to the total area, but over the course of the whole summer, I collected ~5 square meters worth of artificial grass mats, with essentially the same result every time, nothing. Given the amount of hours it takes to locate and collect the squares, then process them, it is alot of work, trust me on that. It just seems to me that supply is very low. Even in the collectors we aren't getting that many, 10-20 per collector, and those are on a mesh that has more surface area than my recruitment squares and are enclosed and thus less likely to be preyed upon. My recruitment squares also don't have that luxury, and I did this on purpose. Maybe next year I will do a predicted vs apparent recruitment survey. I know I am missing some, since we did collect one large seed ~30mm on one of my squares, but not attached to my grass. At least this is a good sign that there are probably some seed out there, and I am hoping in November to do some bottom surveys to find out.
Well, I can't be very sure about that. However, there was a time when Great Souht Bay, a south shore estuary on New York's Long Island, when there were so many hard clams that people could "walk across the bay on the boats of clammers." Well, the times they are (read have been) a changin'. One of the projects my lab has been involved in was a shallow water hard clam survey in GSB. I was able to go out and help with that survey last week, and I can say the results, at least for my day out on the water, the results were less than ideal. Times were, there were upwards of 30-40 hard clams per square meter at certain locations within GSB. I'd say we were lucky to find ~ 1 per square meter. That is devastating. Certainly overfishing helped contribute to this collapse, but additional insults such as harmful algal blooms and habitat alteration has certainly helped lead to this sad clam state. There is hope, though. The Nature Conservancy has a large area of bottom land in GSB and has been free planting adult clams in spawner sanctuaries for many years. Hopefully, things will start to get better.
So I went to measure my scallops on Tuesday for my growth experiment, which if I had to say, is going fairly well. I conducted a similar experiment last year and ended up with good results, so I added more mats this year and hoped to see much of the same. It was a long day (at Southold by 8:30, leave the dock by 9:30, back tot he dock by 5:30, leave Southold by 6:30), and I ended up that night with a killer headache, ended up sleeping for 12 straight hours, which never happens to me, but that is a horse of a different color. The water has cooled down considerably, but it was none-the-less a nice day diving on my grass mats. As soon as I got to the bottom, I saw a huge winter flounder, we are talking dinner for 4 (well maybe not quite that big, but big), and of course I didn't have my catch bag or my camera, but I still tried to grab it by its tail and it swam away. Aside from the flounder, the usual suspects were all out - tautog, cunner, porgies, sticklebacks, gobies, spider crabs, mud crabs, and even blue crabs. And this knobbed whelk, crawling along the bottom, leaving his mucous trail along the way. Oh, and adult scallops. I found one in my mat that at first glance looked like a really big seed. As it turned out, it was a scallop with a small growth ring, sometimes called nub scallops. These scallops are usually spawned late in the year (October) and only grow a few millimeters until their growth stops for the winter. The next season, they catch up to the other scallops, and end up around the same size. I also saw this guy, who was posing for pictures. All in all, nice day on the water, and my scallops are looking good.
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.