Thursday, March 29, 2007

My reseach

Just wanted give a little background information on my proposed research

Estuaries in Long Island, New York, have been documented as some of the most productive in terms of both primary production and shellfish harvest (COSMA 1985). Bay scallops, Argopecten irradians, once supported a vibrant fishery that contributed to high productivity in Long Island waters. Scallop populations crashed in 1985 after the occurrence of the first brown tide, Aureococcus anophagefferens, in the Peconic Bays, and subsequent blooms pushed scallops to the brink of extinction (Tettelbach and Wenczel 1993). Reseeding efforts commenced after the blooms with relatively little success (Tettelbach and Wenczel 1993). One potential reason for the lack of recovery was the low densities of spawning adults, as numbers of adult scallops in the Peconics has rarely been over 0.5 animals/m2 over the last 10 years (Lewis and Rivara 1998). Competition and intense predation may be contributing recovery failure, but I hypothesize that the major contributing factor is loss of habitat. Low survival leads to low densities of adults, and scallop survival has been most often linked with predation (Tettelbach 1986; Prescott 1990; Tettelbach, Smith et al. 1997). Also, predation rates are much lower in vegetated habitats when compared to bare sand (Prescott 1990; Tettelbach, Smith et al. 1997). Locally, bay scallops preferred habitat is eelgrass, Zostera marina, an association that has long been recognized (Belding 1910; Gustell 1930),and examined in multiple studies (Pohle, Bricelj et al. 1991; Garcia-Esquivel and Bricelj 1993). The same brown tide blooms that caused the scallop population to crash also shaded out eelgrass (Dennison 1987). High nutrient loads from increasing development of the East End of Long Island can also lead to eutrophication, which has devastating impacts on eelgrass (Dennison, Orth et al. 1993) and leads to dense macroalgal blooms (Valiela, Foreman et al. 1992). Fishing gear directly removes eelgrass biomass (Boese 2002). The aforementioned factors have led to current Zostera beds in eastern Long Island to exist as a mosaic of patches that vary in shape, size, and degree of isolation from other patches. Habitat patch size can significantly affect recruitment (Bologna and Heck 2000) and survival (Irlandi, Ambrose et al. 1995) of marine bivalves. Furthermore, a regime shift from an eelgrass dominated system to a macroalgal dominated system can potentially be detrimental to bay scallops (Valiela et al 1992). The relative value of different juvenile scallop habitats has received little attention, and few studies have examined the role that changing eelgrass patch architecture (ie, size, shape) has in scallop recruitment, growth and survival. Understanding how changes in Peconic basin habitats may affect bay scallops is paramount for their successful restoration and recovery efforts.

I plan to build artificial seagrass units (ASU) of two different shapes and sizes, replicated in triplicate, using Vexar mesh and polypropylene ribbon. I am using ASUs to correct for confounding variables like shoot density, canopy height, etc. ASUs have been used in previous studies (Bologna and Heck 2000). I will be able to test recruitment, growth and survival of scallops within these patches. Also, in field experiments I will test survival in different habitat types, eelgrass, codium, mixed macroalgal communities, crepidula, and bare sand. Eventually I also plan to conduct a diver benthic survey throughout the Peconics for submerged aquatic vegetation using the Braun-Blanquet method to determine whether or not there are suitable habitats for restoration, and present the results to Suffolk County, Easthampton Township and Southold Township.

Belding, D. (1910). A report upon the scallop fishery of Massachusettes. Boston, The Commonwealth of Massachusettes.

Boese, B. (2002). "Effects of recreational clam harvesting on eelgrass (Zostera marina) and associated infaunal invertebrates: in situ manipulative experiments." Aquatic Botany 73: 63-74.

Bologna, P. and K. Heck (2000). "Impacts of seagrass habitat architecture on bivalve settlement." Estuaries 23: 449-457.

COSMA (1985). Suffolk County's hard clam industry: an overview and an analysis of management alternatives, MSRC SUNY Stony Brook.

Dennison, W. (1987). "Brown tide" algal blooms shade out eelgrass. National Shellfish Association, Halifax, Nova Scotia.

Dennison, W., R. Orth, et al. (1993). "Assessing water quality with submerged aquatic vegetation-Habitat requirements as barometers of Chesapeake Bay health." Bioscience 43: 86-94.

Garcia-Esquivel, Z. and V. Bricelj (1993). "Ontogenetic changes in microhabitat distribution of juvenile bay scallops, Argopecten irradians irradians (L.), in eelgrass beds, and their potential significance to early recruitment." Biological Bulletin 185: 42-55.

Gustell, J. (1930). "Natural history of the bay scallop." US Bureau of Fisheries Bulletin 46: 569-632.

Irlandi, E., W. Ambrose, et al. (1995). "Landscape ecology and the marine environment: how spatial conifguration of seagrass habitat influences growth and survival of the bay scallop." Oikos 72: 307-313.

Lewis, D. and G. Rivara (1998). An assessment of shellfish resources in the tributatires and embayments of the Peconic Estuary, Cornell Cooperative Extension. Peconic Estuary Program.

Pohle, D., V. Bricelj, et al. (1991). "The eelgrass canopy: an above-bottom refuge from benthic predators for juveinle bay scallops Argopecten irradians." Marine Ecology Progress Series 74: 47-59.

Prescott, R. (1990). "Sources of predatory mortality in the bay scallop Argopecten irradians (Lamark): Interactions with seagrass and epibiotic coverage." Journal of Experimental Marine Biology and Ecology 144: 63-83.

Tettelbach, S. (1986). Dynamics of crustacean predation on the northern bay scallop, Argopecten irradians, University of Connecticut.

Tettelbach, S., C. Smith, et al. (1997). "Bay scallop stock restoration efforts in Long Island, New York: approaches and recommendations." Journal of Shellfish Research 16: 276.

Tettelbach, S. and P. Wenczel (1993). "Reseeding efforts and the status of the bay scallop Argopecten irradians (Lamark 1819) populations in New York following the occurence of "brown tide" algal blooms." Journal of Shellfish Research 18: 423-431.

Valiela, I., K. Foreman, et al. (1992). "Couplings of watersheds and coastal waters: Sources and consequences of nutirent enrichment in Waquoit Bay, Massachusettes." Estuaries 15(4): 443-457.

3 comments:

Tait said...

awesome...glad one of my friends is finally doing some research I find interesting. Good luck with it and make sure to post some updates...if you don't I"ll have to actually pick up the phone and call you...and thats just too much work.

Christopher said...

Intresting stuff John, best of luck with it.

John said...

John - we should catch up sometime. I am a marine ecologist in MA and also growing oysters and scallops commercially. Doing some research too. Give me a shout: john@saquishscientific.com

John Brawley