Date of Award

2013

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Environmental Sciences

Specialization

Fisheries, Animal and Veterinary Science

Department

Fisheries, Animal and Veterinary Science

First Advisor

Joseph T. DeAlteris

Abstract

While the near shore marine environment has been demonstrated to be a productive habitat, little is known about this finfish resource in this habitat in the northeastern U.S. This is primarily due to the difficulties of sampling in this environment, high variability in fish distributions, and lack of a standardized sampling approach, so as to be able to compare different studies. The focus of this work is to better understand the ecology of the near shore marine finfish distribution in the northeastern U.S. This is accomplished through identifying the finfish species inhabiting the surf zone environment and providing a description of their distribution variability. These findings are compared to data from adjacent marine systems and are used to make general sampling recommendations for future monitoring of this resource. Additionally, the concept of a distinct transitional zone (TZ) joining the Acadian and Virginian provinces for the near shore marine demersal finfish assemblage is introduced. Both the role of Cape Cod as a zoographic boundary and the properties of the TZ are investigated by use of a biogeographical species ratio estimator, a quantitative measure for assessing species distributions and biogeographical boundaries. Finally, variability in finfish distribution related to tidal stage and short term migrations are investigated. These distribution characteristics are used to make sampling recommendations for both the dominant finfish species and the total finfish community.

Manuscript I: This study investigated the characteristics of the surf zone finfish on Cape Cod, providing an inventory of the finfish species and a description of their distribution variability. The findings are compared to the available finfish data from adjacent marine systems and are used to make general sampling recommendations for future monitoring of this resource. A consistent seasonal pattern across water temperature, proportion of subtropical fish species, and diversity demonstrated the near shore finfish community on Cape Cod is very much like that of its nearby estuaries of Wellfleet Harbor and Pleasant Bay. Proportion of subtropical fish species was investigated by use of a biogeographic species estimator ratio calculated as: subtropical species (S)/(subtropical + temperate + polar species (A)). Future sampling efforts should include both a haul seine and beach seine as the gears detected differing finfish species and be conducted seasonally as assemblages were shown to vary by month. While this effort proved logistically difficult for consistent monitoring, these results demonstrate intermittent sampling would likely detect large perturbations to the system.

Manuscript II: The near shore finfish ecology is further examined with the introduction of the concept of a distinct transitional zone joining the near shore marine demersal assemblages of the Acadian and Virginian provinces. Additionally, the role of Cape Cod as a zoographic boundary was investigated by use of a biogeographical species ratio estimator (S/A ratio) calculated from the Massachusetts Division of Marine Fisheries Trawl Survey. Analyses identified the TZ as a zone of enhanced diversity where rate of change of the S/A ratio with respect to latitude was maximized. In this region the S/A ratio proved useful as a quantitative measure for assessing species distributions and biogeographical boundaries.

Manuscript III: Additional sampling was conducted at Matunuck Beach, Rhode Island to determine the potential to evaluate changes in the finfish distribution with tidal stage, and the influence of tidal stage relative to that of short term variability. Recommendations for future sampling of both the dominant finfish species and the total finfish community are made based on this research. Tidal stage investigations revealed no effect of tidal stage on the number of species present among or within sampling events. Tidal stage analyses were confounded as the influence of tidal stage was exceeded by finfish short term distribution variability. A 50% reduction in daily effort, for a total of eight hauls, would identify 100% of the dominant species and 85% of the total species detected.

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