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...
Maybe I was expecting a battle royal of sorts. I mean, I had seen Dr James Ammerman of NY SeaGrant take the government position on the Gulf oil spill, painting a rather rosey picture of whats happening down there. And I have read Carl Safina's blog posts, seen him on TED talks and watched him on Colbert talking about the devastation of this ecological disaster. So you might imagine how excited I was to learn that both men, affiliated with Stony Brook's School of Marine and Atmospheric Sciences, would be on a panel discussing the oil spill. I imagined the gloves would be off in a no-holds barred slugfest between a government scientists and a staunch conservationist.
I was telling everyone to go. I predicted a lot of yelling.
I was disappointed. I guess I should say I wasn't disappointed by the news. It was encouraging to hear the consensus agreement that it could have been much, much worse. Despite not knowing the exact impact due to lingering effects for a considerable amount of time, everyone on the panel seemed to agree that the oil dissipated quickly, the scenes of oiled animals occurred in a very small portion of the Gulf, and oil only reached a very very small percentage of the marsh lands. No shouting. No fisticuffs between Ammerman and Safina, or any of the other members on the panel for that matter.
And, while they all stopped short of calling the spill the worst anthropogenic ecological disaster in US history, they did raise some very alarming issues. Basically, the panelists agreed that of greater concern for the Gulf ecosystem is the increasing dead zone and the loss of salt marshes. While the oil spill was an acute occurrence that will likely have some lingering effects, both the dead zone and marsh losses are Gulf impacts that are occurring over a long timescale and will continue to have considerable long term effects. In the question-answer period, Safina pointed out that the Gulf of Mexico has a large amount of natural resilience, as long as the ecological factory is still there - but that factory is the salt marsh, an important habitat which is vital for many species during various portions of their life histories. It is this reason that the dramatic loss of wetlands should be of much greater concern than any one oil spill. Without marshes, many species wouldn't be able to recover.
And yes, while this might seem a little sympathetic toward the oil companies, the truth if that this is a 20-30 billion dollar industry in the Gulf and as long as people continue to drive and use petroleum products, the industry won't go anywhere. We are all contributing to that problem. This event should have strengthened our resolve for clean energy, but as a NATION, we need to encourage a change in policy. That just doesn't seem to be happening. And while I don't like to get political on here, with the expected results of the coming election, we will be farther away from a clean energy nation despite the events in the Gulf, and our ever increasing pumping of CO2 into the atmosphere. This is why its important for everyone to vote, even if you have lost faith in your party or aren't enthusiastic about any candidates, remaining on the sidelines could have very serious repercussions.
Or, sSELF for short. I just recently learned about this program when I attended the New York Marine Science Consortium annual conference. The idea behind this program is that it gives groups, such as schools, the opportunity to be active stewards by monitoring their local environments. The south shore estuary system extends from highly impacted water bodies in the west, to less impacted embayments to the east, and encompasses a watershed with a variety of land uses. The program aims to educate citizens on some of these issues while allowing them to become active in collection of data that helps scientists monitor the estuaries. The program gives interested groups all the equipment and training they need to get started on the monitoring. This started back in 2007 and now has 35 different groups that have contributed to 400 different data sets. In addition to local schools around Long Island, other citizens groups also participate, including the Sierra Club and SPLASH - a group of concerned citizens, started by local fishermen, whose goal is to remove waterfront pollution through both public awareness and individual participation. It is an interesting program, and I hope to become involved with some local schools getting this established on the East End.
The results of the 10 year long study on all walks of marine life ended recently, and the results have recently been released, reports an article on CNN.com. This "decade of discovery" was started by a Rutgers researcher and ended up using data collected from over 2700 researchers from 80 nations - quite the collaborative effort. These scientists collected data on the smallest bacteria to the largest whales, from the frigid Antarctic to the balmy tropics and everywhere in between. General conclusions: the oceans are much more connected and the species are much more diverse than previously thought. And that most of the species are as yet unidentified. You can read some research highlights here and check out many of the images from the decade long study here.
All in all, a very exciting conclusion to an epic task of trying to understand, survey, and catalog ocean life.
True, the northeast used to be a hot spot for white sharks. There were a great many sightings in the 50s and 60s, sighting of both juveniles, adults and even some pairs that were believed to be mating. While little is known about the white sharks around Long Island at this time period, Dr. Chapman said that some researchers believe this might have been a spawning and nursery ground. That being said, there is little data on white sharks from this time period other than sightings. White shark fishing then became quite common, and some of the largest white sharks ever caught were landing on Long Island, particularly out in Montauk, where Captain Frank Mundus was renowned for being a top shark fisherman.
What happened over the course of the past decades is that white shark populations have dwindled in the northeast. While there might be some debate as to the magnitude of the decline, I think most researchers will agree that it is significant. Dr. Chapman is looking to use genetic tools to get a grip on how small (or big) the white shark population might be. Using samples from around 50 sharks, the data thus far shows that northeast white sharks have a low genetic diversity, indicative of a species that has experiences a considerable decline, also known as a bottleneck. This could be potentially devastating to coastal ecosystems along the US, as these animals are apex predators in the coastal food web.
So maybe the white shark advisory shouldn't have been alerting the public about their presence in the waters of New England, but perhaps, they should have been warning us about their disappearance.
That all being said, I am no shark biologist, and the above information was from my notes at the lecture. To learn more about sharks, you should check out some other websites, like the one about New England Sharks, and other blogs by people in the know, such as this entry at Ya Like Dags
However, the new article as it appeared today talked about sea lions now beginning to consume female sturgeon as they reach these dam points. This is a relatively new idea. It appeared in a Northwest Council report about strategies to address the sturgeon population. Not sure if this is a prey switching situation, as my recent online search hasn't turned up many results. But this was a finding in the above report:
"Limiting Factor:Marine mammal predation
Primary Threat:Predation by sea lions on sub-adult, adult, and spawning-size white sturgeon below Bonneville Dam.Oregon and Washington Department of Fish and Wildlife staff have directly observed more that 150 white sturgeon being preyed upon between January 2006 and May 2007, more than 60% of which were spawning-size fish.These are actual numbers based on direct observations during other sampling activities, not a targeted sampling effort; the actual number of white sturgeon taken by sea lions is likely much higher. Steller sea lions appear to be especially effective in preying upon large, spawning-size sturgeon, and may selectively capture fish of this size.
Strategy:Conduct non-lethal hazing actions on the Columbia River to deter California and Steller sea lions from feeding on white sturgeon.
Measures: Hazing with acoustic and percussive devices, flares, and rubber bullets has been shown to be relatively effective in deterring predation on white sturgeon by Steller sea lions in the area immediately below Bonneville Dam.Hazing has been an ineffective deterrent for California sea lions.Steller sea lions have been appearing earlier in the year each year since first sited near Bonneville Dam.Hazing to protect sturgeon should begin when Steller sea lions are first sited near the dam in each year.In 2007, hazing began in mid-December from Bonneville Dam downstream approximately six miles to Navigation Marker 85.Hazing will take place four days a week during daylight hours.Separate from the hazing efforts, fishery managers from Washington, Oregon and Idaho are seeking federal approval to use lethal means to remove individual California sea lions from below Bonneville Dam that prey on white sturgeon as well as Chinook salmon and steelhead listed for protection under the federal Endangered Species Act (ESA).Efforts to date have focused on the area immediately below Bonneville Dam, but predation by sea lions on white sturgeon is known to occur throughout the lower Columbia River."
Well back to the article, its brief, but basically it talks about observations of the sea lions eating sturgeon on the Columbia River. And while this isn't being observed at the Fraser River yet, given the still increasing sea lion and seal populations, its probably only a matter of time.
(My best shark photo, sorry!) So I check out Underwater Times from time to time to see whats new in the underwater news world. So when I happened upon this article from the United Arab Emirates, it reminded me of a Science paper that came out a few years back that is near and dear to my heart. But first, the news article. Essentially, sharks are a major fishery in the Arabian Gulf. From 1985 to 2000, shark landings in the UAE ranged from 1350 to 1900 tons of sharks, and the UAE is a major exporter of shark fins to Asia. However, scientists and fishermen alike have started to notice that the loss of shark predators has impacted the ecology of the Arabian Gulf. This has lead to a study to be undertaken examining these impacts.
In the article, a sentence mentions how the loss of sharks on the Atlantic coasts has lead to a collapse in bay scallops. So you guessed right, this is where the 2007 Science paper which I find so particularly fascinating comes in. This paper, entitled "Cascading Effects of the Loss of Apex Predatory Sharks from a Coastal Ocean," by the late Ransom Myers and others detailed a study whose base conclusion was that the loss of sharks due to overfishing cascaded down the food web and resulted in the loss of bay scallops in North Carolina. They examined fisheries data for trends in individual species of elasmobranchs, the family of fishes to which sharks belong, from 1970-2005 between Cape Cod, MA and Cape Canaveral, FL. They were able to demonstrate strong decreasing trends in the abundance of great sharks, which are the apex predators. Over the same 35 year period, the populations of smaller elasmobranchs, including smaller sharks, skates and rays, were shown to be increasing. Many of these species, and the cownose ray in particular, are known consumers of benthic prey, including a variety of shellfish. In North Carolina, cownose rays move into the estuaries to feed in the summer, and were capable of removing entire bay scallop populations before they could spawn, and decimating populations to a point that densities were so low, that successful fertilization could not take place. By 2004, the North Carolina scallop fishery was gone. These mesopredators are also likely to be impacting the recovery of other shellfish species through consumption. Thus, the loss of sharks, even through by-catch, is likely to have devastating ecosystem impacts, not just in North Carolina, but likely in many coastal areas. (For other reasons why sharks matter, check out this website, this cool blog called Ya Like Dags, and the ongoing series of shark posts over on Southern Fried Science).
Myers RA, Baum JK, Shepherd TD, Powers SP, & Peterson CH (2007). Cascading effects of the loss of apex predatory sharks from a coastal ocean. Science (New York, N.Y.), 315 (5820), 1846-50 PMID: 17395829
Another paper that came out of the Charles Peterson group (he was a co-author on the above Science paper) investigated restoration options for scallops in North Carolina. Obviously, cownose rays still prevent a major problem. One mode of restoration they examined was a way to protect adult scallops in a spawner sanctuary from predation by the rays. They were able to accomplish this via a fairly simple method of using PVC stakes into the sediment that reached out of the water at high tide, evenly spaced narrowly enough so that the rays could not fit inside. This method was capable of successfully maintaining dense populations of adult scallops during the period when the rays were in the estuary. Obviously, allowing populations of adults to survive to spawning is a major step in enhancing scallop populations.
Stephen R. Fegley,* Charles H. Peterson, Nathan R. Geraldi and David W. Gaskill (2009). Enhancing the Potential for Population Recovery: Restoration Options for Bay Scallop Populations, Argopecten irradians concentricus, in North Carolina Journal of Shellfish Research, 28 (3), 477-489 : 10.2983/035.028.0309
There is an interesting blog over on discovermagazine.com about the way sea walnuts (or ctenophores, or Mnemiopsis leidyi) feed (in addition to a cool video, which is posted below). Apparently, these organisms use their cilia to create almost undetectable currents, and they are then capable of catching unsuspecting prey with great efficiency. Due to their incredible ability to feed stealthily and efficiently, they have been particularly devastating invaders in European water bodies. When these comb jellies showed up in the Black Sea, they contributed to a food web collapse by consuming many of the fish larvae that would typically serve as the base of the food chain. In fact, gelatinous zooplankton are often considered productivity dead-ends; they consume productivity in the forms of other plankton, however, they offer little food value to other species. So the productivity is not transferred to other trophic levels, and food webs collapse. This is also becoming a problem in human impacted systems.
This blog made me remember some research some colleagues at the School of Marine and Atmospheric Science conducted. PhD student Marianne McNamara, under the tutelage of Darcy Lonsdale, investigated the impact of high abundances of ctenophores on larval bivalve mortality.
In their article "Shifting abundance of the ctenophore Mnemiopsis leidyi and the implications for larval bivalve mortality," published earlier this year in Marine Biology, McNamara et al investigated how ctenophore abundance has changed, their digestion rates, and finally, their ability to control bivalve larvae. The data from this article is of particular importance for the hard clam restoration and management effort in Great South Bay, NY (their field sites), since the comb jellies may exert a strong predation pressure on hard clam larvae.
They conducted field surveys to investigate the abundance of ctenophores and other zooplankton. They enumerated and took volumetric measurements of the comb jellies, then looked at their gut contents. Finally, they conducted lab feeding experiments, and then used equations to calculate their ability to control bivalve larvae.
McNamara et al found high densities of ctenophores in the early summer, and larger ctenophores in the late summer, and when compared to the literature, densities were considerably higher than in previous decades. This is of particular importance, since bivalve veligers made up approximately 63% of the ctenophores' gut contents, indicating this is a particularly valuable food source for the jellies. In addition, using their equations from densities and feeding rates, they predicted that at peak abundances, the ctenophores could consume over 94% of the bivalve veligers in Great South Bay. This is a particularly alarming figure. In addition, the peak abundances of ctenophores occurs earlier in the year (early summer) now than it did decades ago (in the fall), putting peak abundances of comb jellies in the water column at the same time as the bivalve larvae.
Clearly, this study illustrates the potential ecosystem impacts of increasing gelatinous zooplankton. While they have already been shown to be particularly harmful as invaders, it is now apparent that they can have impacts where they are native as well. It is likely that increasing human impacts leading to pelagic dominated production will lead to more ctenophores in coastal systems, which can prevent benthos from reestablishing in these areas. This might be the case in Great South Bay, where the hard clam populations are struggling to recover despite the Nature Conservancy's efforts at replenishing them. Now I don't know about their high end estimates, as one could imagine if ctenophores were capable of consuming essentially all of the bivalve veligers, then veligers and comb jellies wouldn't be collected together in plankton tows. However, it is clear that ctenophores can possibly have a major impact on a local ecosystem.
McNamara, M., Lonsdale, D., & Cerrato, R. (2009). Shifting abundance of the ctenophore Mnemiopsis leidyi and the implications for larval bivalve mortality Marine Biology, 157 (2), 401-412 DOI: 10.1007/s00227-009-1327-6
If you live in a certain part of North Dakota, that is. I have only been to North Dakota once (for the NJCL conference), so I have limited experience. But I imagine its a very nice place with very nice people. Well I came across this AP article about a place called Devil's Lake, North Dakota. Apparently, this lake is an endpoint for local water run-off; that is, it has no drainage, no natural rivers or streams allowing the water that accumulates from rain and snowmelt to flow out of the lake. So this lake has been growing over the past few decades, getting deeper and larger in size. Since 1990, 400 houses have been moved or destroyed due to the rising waters. Small towns are in danger of becoming inundated, while others were essentially bought out in entirety, by state and federal governments and are now submerged. The waters have risen so high in recent years that the lake is only 6 feet from overflowing, which would be devastating to many downstream towns and communities. A breach of the flood banks would send water into communities near and far, with estimates of flooding exceeding any previous floods. There is considerable debate about what to do with the problem. But for right now, residents just wait for the slow moving devastation.
If nothing else, check out the article here. It has a really cool animated graphic showing the lake in the 1980s and the lake today.
Now, the basic summary of the article is that a group of local baymen had raised some money to plant seed hard clams in Hallock Bay, NY. If you have followed my blog at all, then the name Hallock Bay should sound familiar to you - its the location of one of my dissertationprojects and a place I spend a lot of time in the water (and here, and here). Anyway, back to the article. The baymen released 85,000 8-month old notata clams - about the size of a thumbnail - into a portion of Hallock Bay. They selected a bottom with considerable cobble as their planting area in the hopes that the structure will protect the juveniles from their predators like whelks and crabs.
First, it is exciting to hear about local baymen - commercial fishermen who often get a bad rap when it comes to preserving marine species - trying to do something to help the bay. Some of the original scallop restoration efforts were started by baymen. But the most interesting and exciting part of this article for me was the 8th paragraph: "The fishermen agreed that Hallocks Bay is a good spot for clamming, but they pointed to a broad swath of coastline, opposite the grounds they were seeding, that has been closed for two years -- not because of poor water quality but because of a study Stony Brook University students are doing to see if they can simulate eelgrass bed habitats with synthetic eelgrass."
That's me! While the project isn't exactly described right, and I am not mentioned by name, it is still quite exciting to see my work in the paper, regardless of how small or anonymous.
Well it has been a few weeks since I've posted on some research articles. But then the Journal of Experimental Marine Biology and Ecology published a manuscript about cod responses to expanding seagrass meadows. In addition, a paper out of Japan earlier this year talks about the loss of fish species with the loss of an eelgrass meadow. Combined, these point out the obvious, many finfish are dependent on seagrasses for habitat. However, its not just typical seagrass-associated species that are affected by the loss of seagrass.
First, what happens when seagrasses disappear? There is a wealth of literature that suggests disappearing seagrasses has many negative consequences for both resident and transient species. Many species, including numerous commercially important species, utilize seagrass as a habitat for at least some portion of their life cycle. A paper by Yohei Nakumura examining seagrasses next to l reefs demonstrated that seagrass loss has an impact on the abundance and diversity of fishes, including reef associated species. A series of disturbances, particularly typhoons, decimated a seagrass meadow near a reef, to the point where in 2009, the seagrass meadow had totally disappeared. This caused a 80% reduction in the number of species and a 90% reduction in the total number of individual fish along transects at the same site before and after the disappearance. In addition, they monitored a nearby undisturbed site as a reference, and there was no difference in the abundance or diversity of fishes over the same time period. Many of the fishes that disappeared weren't just seagrass residents, but also coral dwellers. In fact, the only species that didn't seem affected were some gobies. The reason for the loss of fish might not be the eelgrass itself, although the habitat does provide shelter from predators, but could also be due to loss of food for many of the fish - tiny crustaceans that live amongst the seagrass.
A more recent paper involves the increase in abundance of juvenile cod in areas where seagrass is recovering and expanding. First, I know what you are all thinking, I love cod and eelgrass associations! And second, it is great news to hear that seagrass is recovering in some areas (I can talk more about this later). Apparently, there are seagrass meadows in Newfoundland, Canada, that are recovering and expanding over the past decade. These habitats are nursery grounds for both Atlantic cod and Greenland cod. So, one might imagine that an increase in seagrass would be beneficial to these species. Using biweekly seines to monitor changes in fish abundance, Warren and others were able to demonstrate dramatic increases in young of the year cod in the seagrass habitats, in particularly in those "recovering" habitats. This increase also occurred rapidly with expanding seagrass meadows. This suggests that these fish are capable of recovering quite quickly if enough suitable habitat exists. However, it also suggests that since juvenile cod might respond so rapidly, that any negative changes in seagrass cover can be detrimental to stocks. Combined with the Japanese study, the literature indicates that fish populations may lack resiliency to seagrass loss, and illustrate the need for water quality monitoring and management, as well as seagrass restoration. Otherwise, the news that cod stocks might recover, might be just internet fodder.
Nakamura, Y. (2010). Patterns in fish response to seagrass bed loss at the southern Ryukyu Islands, Japan Marine Biology DOI: 10.1007/s00227-010-1504-7
Warren, M., Gregory, R., Laurel, B., & Snelgrove, P. (2010). Increasing density of juvenile Atlantic (Gadus morhua) and Greenland cod (G. ogac) in association with spatial expansion and recovery of eelgrass (Zostera marina) in a coastal nursery habitat Journal of Experimental Marine Biology and Ecology DOI: 10.1016/j.jembe.2010.08.011
So I've been following some other marine science related blogs recently, and Mike over at Cephalove often posts videos, and I thought I would check to see what kinds of videos of bay scallops are available on the internet. I came across these three, which I will share today, which actually talk specifically about the restoration program on Long Island which I am a part of... enjoy!
This first video goes through the hatchery process:
This is the second part of the video, where the news team goes out on the barge and sees the other side of the scallop project:
The final video of the day is just another look at the longlines:
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.
Here on the East End of Long Island, I was concerned towards the beginning of the week about the impending Hurricane Earl. At that point, it seemed like it might be headed toward us. Of course, I was most concerned with my field experiments, which I can not stop, and then started to think about the overall impacts of hurricanes on the benthos.
From the literature research, it seems as though estuaries are particularly resilient to the impacts of major storms, and in particular, estuaries which frequently experience these issues. Granted, Long Island is not a site of major tropical weather, we do get out fair share of severe weather in the forms of Nor'easters. As a matter of fact, a major nor'easter hit Long Island, New York and New Jersey in March 2010, which brought sustained 60mph winds and gusts up to 73 mph (hurricane force winds are 75mph).
So I started to become less worried. Now I just hope that my experiments can handle any associated surge with the storm, and that all my cages and blocks are still out there next week!
Obviously, a lot can change in the next day or two, but as it is currently, Long Island is still well within the cone of probability of Hurricane Earl. Now, we get lots of predictions every year that this is our year (Long Island is said to be long overdue for a direct hit from a hurricane), and it is inevitable that a hurricane will hit Long Island in the future. I just didn't think immediate future. I was kind of hoping I'd be long gone. After all, Long Island is hardly built for hurricanes. There is really only 3 roads off the Island (and for places out on the East End, only 1 road). This is in addition to being relatively low lying (many places get flooded with just a little rain) and lots of bodies of water which will rise with storm surges. Hurricanes also can potentially disrupt the local environment and ecology, as the last major hurricane (the 1938 Hurricane, and here, here, and images here) opened up the Shinnecock Inlet and changed the South Shore estuary system.
So I am obviously worried about my research as well. I have experiments running out in the field that aren't done running yet, so I need to keep my fingers crossed that my equipment stays in place. Clearly I am selfish in my concern about the hurricane, but who wouldn't be?
In the next day or two I will post an article on the impacts of hurricanes on the benthos, which is a major concern for me and, in my honest opinion, for Long Island, since most of the native benthos don't experience anything like a hurricane.
In the most recent issue of Marine Biology, there is a manuscript addressing the issue of 2 introduced species and their interactions with one another. Its an interesting read - one of the species is a commercially important bivalve, the Manila clam, which was introduced in the early 20th century and is now one of the most commercially harvested clams on the west coast of the US. The second is Zostera japonica, dwarf eelgrass, an introduced seagrass species which can establish itself on tidal flats. The idea is that this new seagrass species may be of detriment to the now commercially important manila clam. While there is certainly literature which suggests that seagrasses might enhance bivalve growth - see works involving hard clams and eelgrass by Elizabeth Irlandi and Mike Judge - it certainly stands to reason that eelgrass dampens water currents, and likely decreases the amount of food available to suspension feeders, particularly those distant from the edge of the seagrass (where the food availability might be enhanced). And so the team led by Chaochung Tsai aimed to investigate the impacts the invasive eelgrass had on the clams, and whether the clams might enhance the introduced grass. They chose 3 habitats - seagrass present, seagrass removed, and harrowed habitats. The presence of seagrass, while not necessarily impacting shell extension of the infaunal manila clam, did significantly negatively influence clam condition (tissue weight to shell volume ratio). On the flip side of the coin, while bivalves have been shown to influence eelgrass growth through nutrient additions - see the Peterson Lab publications - this apparently is not the case for the manila clams and dwarf eelgrass. In this experiment, clams did not enhance growth nor impact sediment porewater nutrients. In fact, the only positive effect of the introduced seagrass was on itself. Pretty interesting (and before I read it, unexpected) results.
Tsai, C., Yang, S., Trimble, A., & Ruesink, J. (2010). Interactions between two introduced species: Zostera japonica (dwarf eelgrass) facilitates itself and reduces condition of Ruditapes philippinarum (Manila clam) on intertidal flats Marine Biology, 157 (9), 1929-1936 DOI: 10.1007/s00227-010-1462-0
Irlandi, E., & Peterson, C. (1991). Modification of animal habitat by large plants: mechanisms by which seagrasses influence clam growth Oecologia, 87 (3), 307-318 DOI: 10.1007/BF00634584 Judge M, Coen L, Heck KL (1993). Does Mercenaria mercenaria encounter elevated food levels in seagrass beds? Results from a novel technique to collect suspended food resources Marine Ecology Progress Series, 92, 141-150
So I am not sure how this blog roll tag meme quite got started. Chuck over at Ya Like Dags tagged me, and Mike at Cephalove tagged him. The idea is that science bloggers of substance (I am so excited to have substance) tag each other to answer a few questions. Since I have been tagged, here it goes:
1) Sum up my blogging motivation, philosophy and experience in exactly 10 words
2) Tag 10 other bloggers of substance in the hopes they check this blog regularly and thus continue the meme. (By the way, I didn't know what a meme was, I had to look it up. Thats how internet savvy I am).
1) Like to use pictures to tell my stories about scallops.
Those are two characters from a series of books by Suzanne Tate. They are pretty good, and geared toward children. I have read one of her books, Skippy the Scallop, to kindergarten classes the last two years. Its one of those things I try to do from time to time.
But I digress. Crabby and Nabby are blue crabs. And that relates to my research how? Well I decided a logical step in the progression of my research was investigating blue crabs as scallop predators. This isn't new. What is new, however, is that blue crab abundance has exploded on Long Island. Now, NY is certainly within the range, but toward the northern limits of their range. With warming temperatures, the blue crab populations are growing here on Long Island. This can create a problem with the scallop restoration efforts here. Why? Well, blue crabs are voracious bivalve predators, and they recruit to submerged aquatic vegetation, and especially seagrasses like Zostera marina. These are the very same habitats to which scallops recruit. So it is entirely likely that the increase in blue crabs in NY will have a significant impact on bay scallops, based on the available literature. That being said, no one has investigated blue crabs in Long Island. So one step of my research is now investigating where the blue crabs are recruiting in a south shore lagoon estuary, Shinnecock Bay. I have been doing this for the last two weeks, but will continue to monitor 3 times a week through October. At these same sites, I am monitoring bivalve recruitment to see if indeed scallops and blue crabs are recruiting to the same areas. Then I will do some mesocosm predation experiments with varying complexities and investigating the canopy of vegetation as above bottom refuges for scallops from the swimming crabs. All in a days work!
Although there are a lot of them associating with eelgrass beds in Shinnecock Bay, NY. Nope, I am hunting for baby scallops. Shinnecock Bay has some of the healthiest eelgrass meadows in Long Island, and in some places within the bay, new meadows are forming. This is great, as many species depend on seagrasses as predation refuges and nursery grounds, including my model organism, bay scallops. Why then are there apparently no scallops in Shinnecock Bay? Well, its not exactly that there aren't any, of course, but that there are so few, they might essentially be ecologically extinct. However, restoration efforts in the Peconics and larval monitoring have turned up some pretty exciting results. And, Shinnecock Bay is connected to the Peconics through a canal, whose gates are left open when there is a high tide in the Peconics, allowing water to flow into Shinnecock Bay. This is a potential source of scallop larvae. While the spawner sanctuaries are quite distant from the canal, there is a growing scallop population around Robin's Island in Great Peconic, not far from the canal. And either way, scallop larvae spend up to 2 weeks in the water column, so it is possible for fairly long distance dispersal. So I thought we might see some scallops in Shinnecock Bay. I certainly saw some juveniles last summer, but didn't see any adults, so their survival is likely very low. One reason is probably predation. The same eelgrass meadows that are valuable for scallops is also a valuable habitat for blue crabs and mud crabs, both of which eat scallops like popcorn (or at least I imagine that's how they eat them). And yet, no one has investigate either scallop or blue crab recruitment in Shinnecock Bay, so that's what I am currently doing. My scallop monitoring has already started, and surprisingly (or maybe not surprisingly), I didn't get the results I was anticipating. Instead of the highest numbers of scallops at the site closest to the canal and diminishing numbers with distance, I had two relatively high spat numbers sites, on either side of the Shinnecock Inlet, opening up to the ocean. Could this mean a possible oceanic transport of scallop larvae into Shinnecock Bay? Is this supply-side ecology? There are clearly not large numbers of larvae, but there is a supply, and it's coming from somewhere, but to be honest, I have no idea where. Soon I plan on sampling for blue crabs, whose larval origin I know is oceanic. If they display a similar settlement pattern, perhaps my question will be answered. On a side note, we did collect a lot of other organisms. All together, over 20 different species of organisms came up on the collectors. The most abundant were scallops, mud crabs, blue mussels, jingle shells and slipper shells. But we also saw 2 types of sea squirts, bryozoans, rock crabs, 4 different species of snails, sea stars, urchins, other bivalves (arcs, angel wings and cockles), scaled worms and other polychaetes. Oh yeah, and a few of these things that I have as yet been unable to identify, although my guess is some sort of nudibranch. So yeah, exciting stuff indeed. (scaled worm)
Seriously, I need them... I have scallops, I have mesocosms, I have artificial seagrass, I have mud crabs. Check that, I don't have mud crabs. I need fish and mud crabs! Wow, who thought getting these things would be so difficult... Went out trawling today with a group of elementary school children on the RV Peconic out of the Southampton Marine Station... We caught some interesting fish, and we caught crabs, just not the ones I am looking for. Oh science, why must you be so difficult sometimes!
Ok, on a more serious note, I am sort of freaking out here. I just got scallops on Monday. They are already around 10-11 mm, and soon they will be too big (assume ~2mm growth per week at this time of year, maybe less in a flow through system). So I want to use them ASAP. In addition, Cochlodiniumis blooming again in Shinnecock Bay. If it gets into our seawater system, my baby scallops are toast. Seriously, its bad. Read about it here, or here, or here if you don't want to take my word for it. So theres two reasons why I need to get started quickly, and yet, it seems unlikely that I will have either mud crabs (probably the most abundant crab out there, you would think I can get those easily) or fish to start my tri-trophic interaction experiments. Ideally, I would like to have tautog, scup and toadfish (which have received varying levels of fishing pressure, and each of which will likely have a differing impact on scallops and mud crabs). Ah well. Here's to keeping fingers crossed!
For years, the "supply-side" ecology has been a common theme describing mechanisms for benthic species distributions and densities. In general terms, the amount and extent of a particular organism is driven by the supply of larvae to a given area. This larval supply can thus be seen as driving benthic community structure, especially for marine invertebrates - as their life cycles contain a planktonic larval stage which allows for dispersal over relatively long distances. Thus, many of these populations are considered "open" and their continuation is dependent on some large supply of larvae. This makes sense, and it has been demonstrated many times in the literature. However, this has often been demonstrated on hard bottom communities. Soft bottom benthos don't always display similar patterns. A recent paper by Dr. Megan Dethier from the Friday Harbor Laboratory at the University of Washington, details an experiment conducted investigated very small, post set, infaunal recruits. Sampling these habitats is often difficult due to the 3-D nature of soft sediments. She was able to demonstrate that for a number of taxa she was working with, the strongest recruitment was not in areas where the largest adult populations existed. This suggests that for many of the soft bottom benthos she studied, the supply of larvae is not limiting the adult populations, but rather some post-settlement processes, such as predation, competition or abiotic stressors.
LEWIN, R. (1986). Supply-Side Ecology: Existing models of population structure and dynamics of ecological communities have tended to ignore the effect of the influx of new members into the communities Science, 234 (4772), 25-27 DOI: 10.1126/science.234.4772.25
Dethier, M. (2010). Variation in recruitment does not drive the cline in diversity along an estuarine gradient Marine Ecology Progress Series, 410, 43-54 DOI: 10.3354/meps08636
This is a particularly interesting article, because "supply-side" ecology doesn't always hold true in soft bottom benthos. I have observed this first hand with the scallop restoration work on Long Island. Over 6 years, we have monitored larval supply of scallop spat at a number of different locations, and then each winter and spring, we conduct benthic surveys for juvenile densities. There isn't always a match between sites where we had the highest numbers of post-set and the highest juvenile densities. The main causes for this mismatch is likely to be predation or physical factors.
On another project, I am investigating scallop settlement on artificial seagrass units. I design collectors to mimic seagrass, each collector has 10 artificial seagrass shoots. Half of the collector (5 shoots) is enclosed in a mesh bag (just under 1mm) and the other half exposed to predation. There is an order of magnitude difference between the number of available settlers (those inside the bags) when compared to those actual "recruits" (those scallops outside the bags). This low pattern of surviving recruits holds up regardless of location within the grass mats (either on small or large mats, at the center or the edge). This indicates to me that predation is a major contributing factor structuring the scallop populations, at least in the estuary in which I work, Hallock Bay, Long Island.
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.