Title

Anthropogenic Impacts on Encrusters in Association with Mercenaria mercenaria in Long Island Sound: Dead Shells are Data, Not Trash

Academic Level at Time of Presentation

Junior

Major

Earth and Environmental Science - Earth Science

Minor

Biology

List all Project Mentors & Advisor(s)

Michelle Casey

Presentation Format

Poster Presentation

Abstract/Description

Long Island Sound is an urban estuary from which many people make their livelihood. Years of pollution and commercial fishing have resulted in decreased water quality, including the intense eutrophication in the western part of the sound near Manhattan and resultant bottom water hypoxia. The aim of this study is to use dead shells to test for the effects of decreasing water quality on benthic fauna. Mercenaria mercenaria is a hard-shelled clam abundant throughout the sound, whose thick and relatively large shell is an excellent substrate for benthic organisms. Long Island Sound was divided into four geographic areas based on their water quality and commercial fishing regulations, with M. mercenaria specimens collected from each. Due to the dramatic differences in oxygen and fishing throughout these areas, one would expect to see certain epibionts (encrusters) and endobionts (borers) associated with the clams. For example, we expect nutrient-loving Crepidula sp. to colonize a greater proportion of shells in the heavily eutrophied west. Results indicate a complex relationship between the E-W dissolved oxygen gradient and encruster abundance, with the greatest abundance and highest rates of encrustation occurring at both ends of the study area. Crepidula was not more abundant in the western portion of the sound as predicted, but other encrusting organisms such as sponges show promise for use as indicators of human disturbance. Additionally, a relationship between areas with and without commercial fishing was observed, namely the fact that Rye, NY, has a greater abundance of filter-feeding barnacles and photosynthetic algae than nearby Greenwich, CT, in spite of their similar water quality. We proposed that a decrease in the amount of turbidity caused by commercial shellfish dredging is the likely explanation as Rye, NY, has no commercial fishing whereas Greenwich, CT, does. Studying death assemblages of mollusk shells can provide a non-invasive look at human impacts on an environment without disturbing the organisms that we are trying to protect.

Fall Scholars Week 2018 Event

Earth and Environmental Sciences Poster Session

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Anthropogenic Impacts on Encrusters in Association with Mercenaria mercenaria in Long Island Sound: Dead Shells are Data, Not Trash

Long Island Sound is an urban estuary from which many people make their livelihood. Years of pollution and commercial fishing have resulted in decreased water quality, including the intense eutrophication in the western part of the sound near Manhattan and resultant bottom water hypoxia. The aim of this study is to use dead shells to test for the effects of decreasing water quality on benthic fauna. Mercenaria mercenaria is a hard-shelled clam abundant throughout the sound, whose thick and relatively large shell is an excellent substrate for benthic organisms. Long Island Sound was divided into four geographic areas based on their water quality and commercial fishing regulations, with M. mercenaria specimens collected from each. Due to the dramatic differences in oxygen and fishing throughout these areas, one would expect to see certain epibionts (encrusters) and endobionts (borers) associated with the clams. For example, we expect nutrient-loving Crepidula sp. to colonize a greater proportion of shells in the heavily eutrophied west. Results indicate a complex relationship between the E-W dissolved oxygen gradient and encruster abundance, with the greatest abundance and highest rates of encrustation occurring at both ends of the study area. Crepidula was not more abundant in the western portion of the sound as predicted, but other encrusting organisms such as sponges show promise for use as indicators of human disturbance. Additionally, a relationship between areas with and without commercial fishing was observed, namely the fact that Rye, NY, has a greater abundance of filter-feeding barnacles and photosynthetic algae than nearby Greenwich, CT, in spite of their similar water quality. We proposed that a decrease in the amount of turbidity caused by commercial shellfish dredging is the likely explanation as Rye, NY, has no commercial fishing whereas Greenwich, CT, does. Studying death assemblages of mollusk shells can provide a non-invasive look at human impacts on an environment without disturbing the organisms that we are trying to protect.