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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Habitat Heterogeneity Concentrates Predators in the Seascape: Linking Intermediate-Scale Estuarine Habitat to Striped Bass Distribution

Kennedy, Cristina 01 January 2013 (has links) (PDF)
Predators are key components of aquatic ecosystems and innovative approaches to understanding their spatial distribution are imperative for research, effective management, and conservation. Discontinuities, created by abrupt changes between two unlike entities, are irregularly-distributed, intermediate-scale features that can have a disproportionate effect on organismal distribution within the seascape. Here I use the discontinuity concept to relate the distribution of a predator, striped bass (Morone saxatilis), to physical features within Plum Island Estuary (PIE), MA. I mapped the distribution of 50 acoustically-tagged striped bass during four monthly surveys at 40 sites to evaluate if heterogeneity in physical features concentrated predators. All striped bass survived tagging, were coastal migrants, displayed seasonal residency within PIE, and moved freely throughout the estuary. However, these highly mobile predators were not evenly distributed. Specifically, striped bass were clustered in the middle region of PIE in response to sandbar area, intermediate bottom unevenness, channel networks, and, to a lesser extent, confluences and drop-offs. The highest predator counts occurred at sites with the greatest additive habitat complexity. I measured 23 geomorphic metrics at 40 sites within the seascape to characterize the spatial patterns of confluences, drop-offs, bathymetry and land features. Then, I mapped integrated measurements of multimetric physical features to reveal distinct spatial trends in physical complexity of the estuary. By expanding the discontinuity concept and combining irregularly-distributed, intermediate-scale physical features with smaller-scale, traditional fish habitat methodologies, I revealed consistent and ecologically-meaningful patterns within a north temperate estuarine seascape.

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