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...
No scallop news to report this time of year. I am in the process of getting my proposal together to defend it this spring, re-writing a manuscript, getting together a presentation for the upcoming Benthic Ecology Meetings, and taking two classes. Crazy right? But somehow, I have found time to renew an old hobby of mine, tropical fishkeeping. When I was growing up, my dad always had fish tanks, and when I was old enough, I started getting tanks of my own. Eventually, between me and my father, we had somewhere between 13-15 fish tanks throughout the house and basement. I tried to continue the hobby in college, but it is hard when you move every 8 months. So I have been out of the hobby for a few years, but was able to obtain a 20 gallon fish tank last September, and I set it up with freshwater (marine ornamentals are difficult and expensive, both in livestock and equipment). Originally, I just had some tetras (lemon tetras mostly) and after the tank cycled, I added some neons as well. After Christmas break, I added some angelfish and catfish. But I always wanted discus. They are some of the most difficult freshwater fish to keep, requiring very specific water quality (low pH, soft water, low nitrogen, high temperature). My father and I tried to keep them a long time ago, but kept having difficulty - which was disheartening, considering we had kept just about every other type of freshwater fish with relatively few problems. Discus are kind of like the holy grail of freshwater fish - breeders kept secrets for decades. But when I went to the pet store the other day, I saw discus at the right size (silver dollar) and the right price (29.99, 4 for 100). My water seemed right (temp ~80, but easily raised, pH ~6, etc) but I still wasn't sure. I probably wouldn't see discus this quality at this price again (especially if the economy gets fixed), but I had two angelfish (body size ~ a quarter) who were now established in the tank for over a month, and the tank was small. Both angelfish and discus are specialized cichlids from the floodwaters of the Amazon river, laterally compressed to swim between the submerged trees. Cichlids, by nature, can be rather territorial and aggressive by nature, and although angelfish and discus are generally regarded as gentle, there was some hesitation on my part. 20 gallon tanks are small - only 24 inches long - and with the angels being established, there isn't room for the discus to escape potential attacks. I thought long and hard. I spent about an hour watching the fish and talking to the store attendant. Finally I decided I won't have another opportunity to get the discus at this price, and I figured I would give it a try. This was yesterday. They seemed to acclimate fine, however, I raised the temperature in my tank anyway, from 80 to 85 (I was hoping only to come up to 82-82, but my heater is not that specific). Then I turned off the light and went to bed. I forgot to consider the potential for the dissolved oxygen to drop when I raise water temperature, and I woke up this morning with all the former residents (tetras and angels) gasping for air, and one of the catfish already dead. I was freaking out. I could not have this. I dropped the temperature back down to just over 80, took an inch of water out so the filter exhaust would stir the water better, and rushed to school to borrow an air pump for the time being. But I had class, so I couldn't stay and watch. I just kept my fingers crossed. When I got home today, I was surprised. All the fish seemed to be breather normally, swimming around, and all were eating (even the discus, after only 1 day!) Catastrophe averted, for now. I will take pictures soon.
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.