Geographic variation in growth and development of spot (Leiostomus xanthurus) and Atlantic croaker (Micropogonias undulatus) in estuarine waters.

摘要

This study examines geographic variation in growth and development of the catadromous Spot (Leiostomus xanthurus Lacepede') and Atlantic croaker (Micropogonias undulatus Linnaeus) (Family Sciaenidae) to test the overall hypothesis that juvenile growth and development are adaptive responses to resident estuarine conditions at different latitudes. This hypothesis is tested by examining geographic (latitudinal) variations in estimated population growth rates from estuarine specific survey data and morphometric and meristic development from samples obtained over the range of spot and Atlantic croaker distribution in the United States (25°56'N, 97°14'W in the Gulf of Mexico to 45°04'N, 66°55'W in the Western North Atlantic).; For both spot and Atlantic croaker, estimated relative population growth (ERPG) rates increases significantly with latitude, supporting the alternative hypothesis (H₁) that significant differences in ERPG exist between latitudes. Regression coefficients (β₁ and β₂) are greater than 0 supporting a latitudinal based summer growth rate. However, the latitudinal distribution of ERPG rates indicates little difference in ERPG rates in the middle latitudes (27°N to 35°N). Differences in ERPG at the northern and southern extents of the geographic range for spot and Atlantic croaker are responsible for the majority of change associated in growth, and are associated with phenotypic adaptations to local abiotic conditions, specifically spring and summer water temperatures.; Morphometric development for young-of-the-year and juvenile spot and Atlantic croaker appears to be homogenous across their latitudinal ranges in the Gulf of Mexico and Western North Atlantic. Size adjusted morphometric development rates were not statistically different over their individual latitudinal ranges. No differences in meristic development were observed for spot >25mm SL or Atlantic croaker >50mm SL.; A data warehouse model was developed to standardized fisheries survey data into entities of information. Minimum data required were modeled to establish flexible relationships to address the key question of latitudinal differences in ERPG. Attributes of sample gear, measurements and summaries (abiotic and biotic), coding libraries (taxa, measurements, locations), sources, and sample relationships were developed to standardize these relationships across survey data sets. (Abstract shortened by UMI.)