My general and broad interests are in estuarine, and in particular, benthic ecology. I am interested in understanding interactions between organisms that live on the bottom and their habitat. My current research involves the bay scallop as a model organism and its interactions with seagrass and potential alternative habitats, and how those habitats affect their recruitment, growth, and survival. More specifically, my research interests are:
Restoration Ecology of the Bay Scallop
The bay scallop once supported a vibrant fishery on Long Island, where I currently reside, as well as fisheries all along the east coast. For a variety of reasons, scallop populations crashed, mostly linked to harmful algal blooms, but also associated with loss of habitat in some locations. Over the past decade, many restoration efforts have been undertaken to restore scallops to their previous densities – these efforts have taken place in Florida, North Carolina, Massachusetts, and, of course, New York. Unfortunately these restoration efforts have met with mixed success. Restoring bay scallops to these areas is important both ecologically and economically, as well as culturally. Understanding how these restored populations of bivalves survive, grow, and reproduce – and in particular, specific locations which maximize all three – is a key to establishing efficient and effective restoration programs. I am involved in the larger bay scallop restoration effort underway in the Peconic Estuary System, on the east end of Long Island underway by collaborators from Long Island University and the Cornell Cooperative Extension. My specific tasks in this effort are on the monitoring and research side of things – larval and juvenile surveys, growth and condition of transplanted scallops, predation, etc.
Habitat Patch Dynamics
Seagrasses form vast underwater meadows, and provide a variety of ecosystem services. However, various factors have caused seagrasses to decline – mostly anthropogenic, some direct (mechanical destruction), some indirect (nutrient loading). The many factors that cause seagrasses to decline have caused many seagrass meadows to shrink, and habitats to become a mosaic of patches which vary in areal size, shape, complexity, and distance between patches. This patchiness can have deleterious affects on associated fauna, as has been demonstrated for a variety of species. Much of this research is completed by using artificial seagrass units (ASUs), which allow researches to correct for confounding variables. Decreasing seagrass patch size and shapes which maximize edges can have a negative impact on bay scallop populations by impacting survival of juveniles. However, smaller patches and maximal edge might positively influence growth (by increasing food availability) and recruitment. Understanding how these potential positive and negative impacts balance is key to understanding the impacts of diminishing habitats and increasing patchiness. My research utilizes 2 sizes (8.5 and 17 square meters) and 2 shapes (circle and four pointed star to maximize edge differential) to investigate the role size, shape and perimeter to area ratios have on recruitment, growth, and survival of bay scallops. While this method has been applied in the literature, it has not been done at this more relevant scale.
Larval Settlement and Recruitment
Larval settlement and recruitment play a major role in population size and structure of benthic invertebrates, like the bay scallop. The supply of larvae plays a crucial role in year-to-year variability in population size of many invertebrates. Larval supply is largely determined by fertilization success, larval survival and transport. Many invertebrate larvae have rather long durations that allow them to be dispersed great distances. In addition, once larvae are ready to metamorphose and settle, many are capable of choosing a suitable substrate. After settlement, a variety of factors impact the survival of benthic invertebrate larvae. This post settlement period is extremely critical, and the period between settlement and recruitment to adult populations is a period of high predatory mortality. While there is literature that suggests high rates of mortality, and size refuges from predation, there is little research on the early 6 week period after settlement for bay scallops. Some preliminary research suggests over an order of magnitude difference in survival between settlers exposed to predator versus those enclosed from predation. Understanding the role that habitat plays on this post-set mortality is also important, and will help in understanding why certain restoration efforts are working and why some are not.
Many studies have examined predator prey relationships in mesocosms and how changing habitat complexity influences these interactions. More recently, studies are examining multiple predator affects and tri-trophic relationships by adding species at different trophic levels. Some interesting results from these experiments include the idea of trophic cascades – when the loss of higher trophic levels indirectly impact lower trophic levels – and the idea behind trait mediated indirect interactions – the idea that the mere presence of an upper trophic level predator can have an indirect impact on lower level consumers by suppressing predation by an intermediate predator merely by their presence. Understanding the roles of multiple predators, and predator-prey interactions, in scallop survival has not been well studied. Is it possible that a trophic cascade of sorts has occurred in the Peconic Estuary System? Many finfish have been overfished, and these species often consume juvenile crabs, so its possible that decreased populations of finfish might be having an impact on bay scallop population growth. Understanding these interactions, and how they are affected by habitat complexity and alternative habitats.
Introduced and invasive species
Novel and exotic species are constantly being introduced into new habitats and new ecosystems. The impacts of these new species can have devastating and long-lasting affects. However, not all introduced species may have harmful impacts; some introduced species can even facilitate native species, in particular, habitat forming species. While not all introduced exotics prove beneficial, a major problem in many ecosystems is habitat loss. New species which fill this void are likely to positively influence native species which are reliant on habitat for some portion of their life cycles. This appears to be the case in the Peconics with an introduced canopy forming macroalgae, Codium fragile, and bay scallops. We have observed scallops associated with Codium often during field surveys, and some of our research suggests that Codium may offer the same habitat benefits as eelgrass in terms of survival. There are always caveats when considering both macroalgae and introduced species as alternate habitats, and examining longer term impacts on growth and survival of scallops in macroalgae, and Codium in particular, is important for restoration efforts, as eelgrass, the preferred habitat, continues to decline in many estuaries.