Spatial and Temporal Variability in the Nearshore Distributions of Postlarval Farfantepenaeus aztecus along Galveston Island, Texas

• Published in: Estuarine, coastal and shelf science Vol. 52; no. 4; pp. 445 - 456
• Main Authors: Benfield, M.C., Downer, R.G.
• Format: Journal Article
• Language: English
• Published: London Elsevier Ltd 01.04.2001; Elsevier
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Animals; Barrier Island coasts; Biological and medical sciences; Demecology; Farfantepenaeus aztecus; Fundamental and applied biological sciences. Psychology; groins; jetties; meroplankton; penaeidae; plankton distribution; plankton surveys; Protozoa. Invertebrata; Texas coast; USA, Texas, Galveston I; Galveston Island; United States; North America; Texas; America; ASW, USA, Texas, Galveston I; plankton distribution; plankton surveys; Texas coast; penaeidae; groins; Barrier Island coasts; jetties; meroplankton; Spatial variability; Environmental factor; Time variation; Coastal zone; Macrura; Crustacea; Marine environment; Penaeidae; Larva; Arthropoda; Decapoda; Invertebrata; Zooplankton; Population density; Ecological abundance
• ISSN: 0272-7714; 1096-0015
• DOI: 10.1006/ecss.2000.0762

The nearshore distributions of postlarval brown shrimp Farfantepenaeus aztecus (Ives, 1891) were investigated at four approximately equidistant sites along a section of Galveston Island, Texas. Simultaneous, replicate plankton samples were collected along with environmental measurements at each site during three consecutive days each week for a period of four weeks during April 1992. The data were modelled using analysis of variance and stepwise regression to evaluate the spatial, temporal and environmental factors contributing to changes in density. Postlarval densities differed significantly among the four weeks during the study, however, day was not a significant model effect. Changes in weekly distributions appeared correlated to the presence of winds favourable for onshore transport of water. The distributions of postlarvae were highly variable along the Island with significantly greater densities at sites located on sections of open beach and significantly lower densities in the vicinity of shoreline stabilization structures (groins and jetties). Turbidity, water and air temperature, salinity, and dissolved oxygen were all significantly related to postlarval density as were several interactions among environmental factors and turbidity and site. The variability observed in the study was used to estimate levels of sampling intensity required to achieve different levels of precision. Based on the high spatial and temporal variability in postlarval densities observed in this study, and our sampling effort calculations, we suggest that some of the difficulty in predicting landings of adult shrimp based on postlarval abundances may be due to insufficient sampling effort to accurately assess postlarval densities.