Title page for ETD etd-1111103-152345

Type of Document Master's Thesis
Author Adamack, Aaron Thomas
Author's Email Address aadama1@lsu.edu
URN etd-1111103-152345
Title Quantifying Habitat Quality of Larval Bay Anchovy (Anchoa mitchilli) in Chesapeake Bay by Linking an Individual-Based Model with Spatially-Detailed Field Data
Degree Master of Science (M.S.)
Department Oceanography & Coastal Sciences
Advisory Committee
Advisor Name Title
Kenneth A. Rose Committee Chair
James H. Cowan Jr. Committee Member
Jaye E. Cable Committee Member
  • chesapeake bay
  • individual based model
  • larval fish
  • anchoa mitchilli
  • bay anchovy
  • jellyfish
  • ctenophore
  • essential fish habitat
  • habitat quality
  • survival
  • mortality
Date of Defense 2003-07-28
Availability unrestricted
Larval bay anchovy (Anchoa mitchilli) habitat quality in Chesapeake Bay was predicted using an individual-based model applied to spatially-detailed field data from Rilling and Houde (1999). Habitat quality was predicted using the ratio of instantaneous mortality rate to instantaneous growth rate. Model predictions of habitat quality were compared to field estimates of habitat quality derived from the spatially-detailed field data. Three sets of one-day simulations were performed to estimate larval growth and mortality rates throughout Chesapeake Bay during June and during July 1993. Field-based simulations used field data to estimate the model inputs of water temperature, zooplankton densities, and the densities and sizes of bay anchovy larvae and gelatinous predators (Mnemiopsis leidyi and Chrysaora quinquecirrha). Standardized larvae simulations used the same field data, but standardized larval sizes and densities throughout the Bay. A third set of simulations was performed to determine the relative importance of six factors in determining the bay-wide spatial variation in predicted growth and mortality rates. Model predictions from the field-based simulations produced spatial patterns of habitat quality in the Bay that sometimes conflicted with the otolith-based predictions of Rilling and Houde. Field estimates of anchovy egg and larvae abundances were generally high in regions predicted to have low M/G ratios, but low in regions with low otolith-estimated M/G ratios. The standardized larvae simulations generally supported the conclusions of the field-based simulations. The effect of habitat quality on larval production was evaluated using the predicted mortality rates from the two sets of simulations. Initial larval abundances dominated the percent of survivors projected 20-days into the future that a region would produce, but when larvae were standardized across the bay, differences in habitat quality among regions was important in determining the relative contributions of survivors by region. Initial larval length and zooplankton densities were the most important factors determining the spatial variation in growth rate, while predator density was most important for mortality rate. Future research should focus on field and laboratory data collection to resolve the discrepancy between model-predicted and otolith-estimated M/G ratios.
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