Spatial and Temporal Patterns of Larval Fish Morphometrics as Indicators of Ecosystem HealthEPA Grant Number: R825350
Title: Spatial and Temporal Patterns of Larval Fish Morphometrics as Indicators of Ecosystem Health
Investigators: Power, James H.
Institution: Louisiana State University - Baton Rouge
EPA Project Officer: Hahn, Intaek
Project Period: December 15, 1996 through December 14, 1999
Project Amount: $165,436
RFA: Exploratory Research - Environmental Biology (1996) RFA Text | Recipients Lists
Research Category: Biology/Life Sciences , Ecosystems
Description:The estuarine larvae of fish are a critical component of those ecosystems they are important forage for other organisms, and if they survive to the juvenile-adult stage they in turn comprise one of the top predators in the ecosystem as well as an important resource for man. During the larval phase these animals exhibit both extremely high growth rates and high mortality rates. Slight fluctuations in the early mortality rate can result in considerable variations in adult population size, with obvious ecosystem consequences. This concept, combined with the rapid growth and development of larval fish, make them a sensitive indicator of ecosystem health. This project is to examine the morphometrics of larval estuarine fish, and to collect information on the magnitude of variation, and spatiotemporal patterns of variability, by an advanced measure of larval fish condition. Its objective is to answer the following questions: 1) What is the inherent variability of field-collected larval fish condition as quantified by morphometric measures, coupled with accurate measures of live fish body mass and body volume?, and 2) Are there spatial or temporal patterns of these morphometric condition indices that can be related to estuarine location or time of year? Are there locations along an environmental gradient within the estuary where larvae are consistently and quantifiably "better," or at least different?
The centerpiece of this research is to examine the patterns of larval shape using a new and exciting analytical approach the thin-plate spline-relative warp analysis. This analysis has been proven to be capable of extracting and quantifying subtle patterns of affine (uniform) and non-linear variations in biological shape. This analysis will be complemented with accurate measures of live larval body mass and volume, using a weight-in-water measurement technique based on Archimedes' principle. This project is expected to demonstrate, and quantify, variations in larval shape among a variety of habitats in the Louisiana Barataria-Terrebone estuarine system, a component of the EPA National Estuary Program. Understanding spatiotemporal patterns of larval morphometric condition indices will help: (1) to reveal ecosystem function by allowing identification and characterization of attributes responsible for that status; and (2) to anticipate the consequences of early assessment of good or impaired condition, and especially to know the subtle effects of anthropogenic change such as pollution or habitat modification.