So anyone following my blog knows that I was actively involved in the bay scallop restoration efforts in Long Island. To refresh, scallop populations supported a vibrant fishery in NY until the mid 1980s, when populations crashed due to the first occurrence of a brown tide bloom, and recurrent brown tides pushed scallops to the brink of local extinction. The brown tide has not occurred in the Peconic Estuary since 1995 (although it still occurs on Long Island waters), so in 2006, restoration efforts started to help jump-start local scallop populations in the Peconics.
Commercial bay scallop landings and Brown tide occurrence
These efforts sought to boost spawning stock and concentrate high densities of scallops in close proximity to enhance fertilization and reproductive success. The idea was that low population densities of adults were limiting reproduction, which was subsequently limiting larval supply and recruitment. The restoration efforts sought to boost adult populations by establishing spawner sanctuaries using an array of lantern nets or by high density on bottom restoration. You can watch a number of videos on these efforts here, or watch the Fox News piece below:
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The restoration efforts had been very successful – every year we see higher numbers of scallop spat than the year before (despite the same effort), and the results have translated to scallops on the bottom and to the fishery. Recently, our group was able to publish some of our findings in Marine Ecology Progress Series.
We were able to demonstrate at all sites annual increases in the mean spat per bag – that means, each year post-restoration, we saw greater numbers of baby scallops in our collectors. This occurred not only in our basins where we actively did restoration, such as Orient Harbor and Hallock Bay, but also in nearby basins with no active restoration efforts, such as Northwest Harbor.
A figure from our MEPS paper, illustrating the annually increasing densities of scallop spat in Orient Harbor. The cross denotes the site of a large lantern net spawner sanctuary.
In fact, scallop spat abundance increased up to 3000% of pre-restoration levels. This was despite that none of the environmental parameters had changed from the 10 years prior to restoration beginning to the 5 post-restoration years we examined for this study. Environmental variables could possibly influence the amount of larvae produced and larval survival. However, temperature, chlorophyll (a proxy for food), nitrogen, monthly rainfall and salinity were not different between the 2 time periods. This suggests that the restoration efforts played an important role in helping to increase the larval availability. In essence, we “primed the larva pump!”
Environmental variables for the pre-restoration period (1996-2006) and the post-restoration period (2007-2010).
Obviously, we were expecting these results and were very excited that we were able to eliminate other possibilities of increased larval supply. Additionally, the dates of peak settlement for the most part lined up with our estimates of spawning dates and settlement.
This doesn’t mean much, however, if it isn’t translating to the bottom, since we collect these scallops in spat collectors hanging in the water column. Many sources of mortality, but primarily predation, can occur from the time the scallop settles on the bottom to the time it can spawn and then contribute to the fishery. I focused most of my dissertation research on habitat and predation on scallops. Some of the cool things from that research suggests that patchy seagrass might not be detrimental to scallop populations and that an invasive species might be a suitable alternative habitat. So, despite limited seagrass in our restoration estuary, we have seen increases in scallops on the bottom.
On bottom increases in scallop densities post restoration
And in many of the basins, these increases in on bottom densities in the fall correlates with the increases in spat fall during the spring of that same year.
Relationship between seed scallop densities in the fall on the bottom in Orient Harbor and the spat per bag landings from the spring.
We are currently preparing this data for a manuscript, showing the subsequent increases in on bottom densities, fishery yield and the economic benefits of the restoration efforts. Hopefully, the success of this project and the information gathered will help other restoration efforts on Long Island, such as the Shinnecock Bay Restoration Project (which I have blogged about ) and elsewhere. I am hoping to turn some of the things I learned with this project (and the many various side projects) to my oyster work here in NC, although I also plan to keep working with scallops.
Yes, I am back. After a looooong hiatus, I am finally back to blogging! (no, seriously, hold your applause). I had been pretty busy the last few months with writing, defending and editing my dissertation (John M Carroll Dissertation). But that is all over now! Defense was successful, edits completed, graduate school accepted, and as of August 16th, I am officially a doctor! So I am hoping that now, I can now get back to writing posts more regularly. I am starting a new position, a post-doc with Dr. Chris Finelli at UNC-Wilmington in the MarBEL (Marine Biofluiddynamics and Ecological Lab) lab. This will be a relatively new field for me, so I am looking forward to learning new methods and working with new people. In fact, I am in Wilmington right now and will be officially starting my position next week – so more to come on that.
But I wanted to make a post today talking about something from my recent past – the Shinnecock Restoration Project (ShiRP). I was involved in preliminary research and monitoring for this project the past two summers, so I am very excited about the big news – $3million dollar donation to restore Western Shinnecock Bay – an area degraded by eutrophication and overfishing and hampered with recurrent harmful algal blooms. This confluence of factors, and likely including other factors such as distance from larval source, has led to shellfish populations in the western portion of Shinnecock Bay extremely low. This is problematic, since the lost shellfish – mainly clams and oysters – are filter feeding organisms and thus act as natural filters for the water column. As their numbers dwindled, water condition worsened, eelgrass cover decreased, harmful algal blooms increased, which affected recruitment of new bivalves to the western bay – a term called a feedback loop. However, restoration has worked to successfully bring back scallop populations to the Peconics – another New York estuary – so there is a lot of confidence that restoration will work in Shinnecock Bay as well.
I am very excited for my colleagues back at SoMAS for this project. The general plan is to combat the decreasing water quality by significantly boosting shellfish populations – on the order of millions – in spawner sanctuaries within the western bay. The idea is that these bivalves will serve two purposes. First, they will increase the filtration capacity of the western bay, removing plankton and thus nitrogen, from the water column. Second, these high density aggregations will have enhanced fertilization success and act as new larval sources, pumping millions more baby shellfish into the bay. Last fall, I was able to be on a trip that planted ~500,000 seed clams into the bay. I was also involved in investigating the growth of seagrass transplants from sites with varying water quality at different sites along the water quality gradient in Shinnecock Bay to identify the most hardy population that could withstand poor water quality in the western bay. This information will be used for the second phase of the project, which is eelgrass restoration.
This past summer, in addition to continuing the spat monitoring which I started in 2011, I also did a hard clam suction survey to give us a baseline idea of clam densities in the western portion of the bay. This was fun – suction sampling for hard clams also turned up all manner of organisms – mussels, razor clams, soft-shell clams, lots of crabs and even some moon snails. But most importantly, we were counting and measuring hard clams, a target fishery species and also a target species for this restoration project. Plus, I also got to learn a little bit of GIS to make maps of distributions, like this one: (I had to remove the map for fear clammers might go to the sites)
The ultimate goal is to restore the water quality, enhance bivalve and eelgrass populations, and enhance local fisheries. I am very excited for this project, and I hope that when I return to Long Island in the future, this academic-public-private partnership will be a highly successful restoration effort. Most importantly, Shinnecock Bay might be perfectly suited for restoring water quality via shellfish enhancement – it is a relatively shallow estuary system (<2m deep except for in the navigation channel which itself is only ~3m deep). Thus, this shallow water body could effectively be filtered by high densities of the shellfish which this project aims to restore. Unlike other much deeper estuaries where the shellfish might not be capable of such an impact, Shinnecock Bay is best suited for this endeavor. Good luck to my friends and colleagues involved with ShiRP!
The south shore of Long Island has a series of interconnected lagoonal estuaries. Shinnecock Bay is the eastern most basin, and it has the least amount of people living along its shores. That’s not to say that there aren’t people out here, it just lacks the uber-development of the more western bays. In recent years, the western portion of Shinnecock Bay has been plagued with brown tides (as has the next bay to the west Quantuck Bay). There was a recent report on NBC News New York on the subject:
The issue is that the brown tides are affecting the Shinnecock Bay shellfish populations negatively. Brown tides were originally responsible for the crash in bay scallop populations over 25 years ago in the Peconic Estuary. Brown tides are a very small phytoplankton that are too small for may shellfish to ingest, and it is also accepted that they produce a sort of toxin that is also harmful to things that eat it, a double-whammy of danger to filter feeders. The problem is these blooms become very dense, essentially outcompeting all other phytoplankton. Since the brown tide becomes the only food available to filter feeders, many either succumb to the toxin or starve to death. This is what happened with scallops in the mid 1980s and 1990s. Luckily, a brown tide hasn’t been seen in the Peconics since 1995 (knock on wood), which led to the restoration efforts I am currently involved with.
However, the brown tide also creates other problems. Some filter feeders, such as clams, appear able to “weather the storm,” so to speak. But brown tides occur at the most inopportune time for hard clams and many other native Long Island invertebrates – spawning season. Clam and other invertebrate larvae are often in the water column at the same time the brown tides appear, and this is extremely harmful to the larvae. A few studies have demonstrated that high concentrations of brown tide can inhibit clam larval growth, extending the larval period and preventing metamorphosis. This has devastating consequences for clam recruitment. Major stressors that occur on basin scales and can severely impact the larvae are likely to lead to recruitment failure (Bricelj and MacQuarrie 2007). In addition, because brown tides inhibit feeding of adult clams, this too can impact reproductive output by affecting gamete formation in adults (Newell et al 2009). This is likely whats been happening in the western portion of Shinnecock Bay highlighted by the above news video.
Brown tides also severely darken the water column. This creates a situation which is harmful to benthic primary producers, such as seagrasses. The brown tide is responsible for shading out eelgrass in a number of Long Island bays (Dennison et al 1989). This has created a loss of a vital habitat for numerous commercially and recreationally important species (which I have blogged about numerous times). This might have been another reason why scallops didn’t recover naturally after the last Peconic brown tide, as eelgrass is often referred to as the preferred scallop habitat. However, hard clams are also known to survive better in seagrass meadows, where the complex root and rhizome structure protects burrowed clams from predators, mostly crabs (Irlandi 1997). Clams also appear to grow better in seagrass habitats (Irlandi 1996, Judge et al 1993).
So now we have a potential triple-whammy for hard clams:
1)Brown tides inhibit feeding in adults, which could impact condition and reproductive output.
2)Brown tides affect the growth of larval clams, preventing metamophosis, and potentially leading to recruitment failure.
3)Brown tides shade out seagrass, causing it to disappear, which has potential negative consequences.
So water quality has deteriorated, and brown tides are becoming an annual occurrence. However, is poor water quality solely to blame? It is also likely that overharvesting of filter feeding shellfish might also play a role in development of brown tide blooms. High densities of hard clams are capable of preventing brown tide bloom formation – densities above current levels but below historic levels, prior to overharvesting (Cerrato et al 2004). It is possible, then, that overharvest of clams (estimated bay wide average for Shinnecock Bay ~1 per square meter) has led to low population densities which are incapable of filtering the water column. This, in addition to water quality issues, allows for the initiation, persistence and recurrence of brown tide blooms, which further prevents hard clam populations from replenishing themselves, a negative feedback loop.
Brown tide in mesocosms with and without clams from Cerrato
This has created some interest in restoring Shinnecock Bay. Both my advisor and one of my committee members are involved in a project investigating the feasibility of restoration, and naturally, I have been tasked to do a lot of work on this project. Before restoration can happen, however, we first need to know the reasons WHY certain shellfish aren’t found in high numbers in Shinnecock Bay. If we are correct in our assumption that recruitment failure due to larval supply is to blame, then we need to investigate recruitment. We are doing this at a series of sites within the Shinnecock Bay-Quantuck Bay complex, and I blogged about this over on the Southampton Patch. If we see many settlers in our collectors, which are generally protected from predators, but we don’t see corresponding numbers on the bottom, we can then correct our theory of recruitment failure to some post-settlement mortality. Once we have this information, we can make better decisions about ways to approach potential restoration projects. And since scallop restoration is working in the Peconics and hard clam restoration appears to be working in Great South Bay, there is reason for hope.
All user groups – baymen, researchers, environmental advocates, recreational users and vacationers – want Shinnecock to be restored to its previous glory, with lush seagrass meadows, clear waters, and loads of clams, crabs, and fish. We need to work hard to achieve this goal. Shellfish restoration will help, but other means are necessary for restoring water quality. Whether that’s sewering the east end, and building tertiary treatment plants, or somehow increasing ocean flushing to the more isolated portions of the bay remains to be seen. However, if everyone involved is as invested as they claim, and that will be the ultimate test, restoration is possible.
Judge, M., L. Coen, and K. L. Heck. 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
Irlandi, E. (1996). The effects of seagrass patch size and energy regime on growth of a suspension-feeding bivalve Journal of Marine Research, 54 (1), 161-185 DOI: 10.1357/0022240963213439
Irlandi, E. (1997). Seagrass Patch Size and Survivorship of an Infaunal Bivalve Oikos, 78 (3) DOI: 10.2307/3545612
Dennison, WC, Marshall GJ, & Wigand, C (1989). Effect of “brown tide” shading on eelgrass (Zostera marina) distributions in: Novel Phytoplankton Blooms: Causes and Impacts of Recurrent Brown Tides and Other Unusual Blooms, 675-692
Cerrato, R., Caron, D., Lonsdale, D., Rose, J., & Schaffner, R. (2004). Effect of the northern quahog Mercenaria mercenaria on the development of blooms of the brown tide alga Aureococcus anophagefferens Marine Ecology Progress Series, 281, 93-108 DOI: 10.3354/meps281093
Bricelj, V., & MacQuarrie, S. (2007). Effects of brown tide (Aureococcus anophagefferens) on hard clam Mercenaria mercenaria larvae and implications for benthic recruitment Marine Ecology Progress Series, 331, 147-159 DOI: 10.3354/meps331147
Newell, R., Tettelbach, S., Gobler, C., & Kimmel, D. (2009). Relationships between reproduction in suspension-feeding hard clams Mercenaria mercenaria and phytoplankton community structure Marine Ecology Progress Series, 387, 179-196 DOI: 10.3354/meps08083
Well, maybe not the most wonderful. But it’s close. I’ve been diving a couple times now, and it is so much better than sitting in the lab. Plus an added benefit is that the water is still pretty clear this time of year. So we have been diving to monitor the spawner sanctuary sites – the 2 bottom planting sites and the long lines. Basically we do quadrat counts of the scallops on the bottom to get an idea of the mortality from time point to time point, and we sample a set of scallops to look at growth, gonad index and condition index. For the long lines we sample scallops from the end lines and the center line to look at growth, GI and CI.
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.
Well, yesterday I worked on the barge – its a boat built by S.P.A.T. volunteers working with the Cornell Cooperative Extension of Suffolk County. It is used mainly for the scallop restoration work, and is equipped with a motorized winch and a star wheel for hauling up lines weighed down by hundreds of lantern nets full of scallops.
This time of the year, the majority of scallops in the nets have spawned at least once, so they need to be relocated to make room for the next batch of scallops to grow-out before overwintering. It can be a labor intensive process as the nets are heavily weighed down by fouling organisms, in particular sea squirts. It is essentially pulling up a net full of scallops, as well as hundreds of little water packets (the squirts) so the nets get pretty heavy. Then, most of the squirts need to be knocked off before the bags can be opened and the scallops dumped on deck, so it is also a very messy process, and sometimes, not very easy as an invasive sea squirt, Styela clava,
have very strong attachment points to the nets and to shells within the nets. Once the nets are cleaned and the scallops dumped onto deck, they need to be released to the bottom. Some of the scallops are pretty fouled (the latter two were collected a day earlier),
but it adds to the camoflage for the scallops on the bottom. The nets also often have lots of little guests in them, including hundreds of grass shrimp and mud crabs, spider crabs, cunner and tautog, and even sculpin.
Sometimes we get pipefish and seahorses from the nets but this is more rare. Additionally, some of this years seed (scallops from earlier spawns this year) have set on the nets and grown very well.
All in all, it was a nice, messy day on the boat with some interesting things to see, including this awesome schooner, the Mary E, on our way home.
At the Cornell Cooperative Extension of Suffolk County’s Marine Environmental Learning Center works a team of eelgrass restoration experts. They have been actively working to restore eelgrass meadows to their past glory throughout the Peconic Estuary, and more recently have been working in Long Island Sound and in the South Shore estuaries. About twice a year they release a newsletter that highlights some of the work they are involved in. The current newsletter also highlights the scallop restoration project being undertaken in Suffolk County, a project which I am involved, and a project that allows me to conduct much of my bay scallop research.
Also, if you would like to visit their website, click here.
I have worked with this group in the past, and all members are very knowledgable in habitat restoration. They have experienced success in many of their transplant and restoration sites, and even developed their own methods for restoration. Now that the importance of eelgrass for many species has been ackowledged by the state of New York, which recently held a meeting of national and international seagrass experts to create an “eelgrass task force” to identify areas of research that are important to understand the dynamics of eelgrass survivng on Long Island and how best to protect it, the job of both the Cornell seagrass restoration team and Dr Brad Peterson’s (of Stony Brook University) Seagrass Rangers, a team of graduate students to which I belong, has never been more important.
To see the seagrass ecology lab website, click here.
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!
Artificial Seagrass
Is a useful experimental tool to mimic natural seagrass while controlling many factors, such as density, canopy height, leaf number, which are usually confounding in natural eelgrass meadows.
Scallops seem to love this stuff!
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