Utilization of estuarine organic matter during growth and migration by juvenile brown shrimp Penaeus aztecus in a South Texas estuary

Abstract

The trophic dynamic links of migratory juvenile brown shrimp Penaeus aztecus were investigated along the South Texas coast from the Aransas Pass to Corpus Christi and Nueces Bay and to the nursery ground in the Nueces Delta. Shrimps and their potential food sources were measured for δ13C and δ15N ratios between December 1995 and July 1996. During this period, shrimp length increased from 10 to 11 mm, when the animals entered Corpus Christi Bay as larvae, to 80-90 mm, when they returned to Mexico Gulf as sub-adults. Brown shrimp exhibited spatial and temporal δ13C variation (from - 25.2 to 12.5‰), indicating a high diversity of food sources throughout their migration. From δ13C values, the main sources used as food sources by juvenile brown shrimp in the Rincon Bayou marsh were Spartina alterniflora and S. spartinae detritus and benthic diatoms. δ13C and δ15N values showed that organic matter inputs carried by the river inflow can also contribute significantly to the feeding of migratory brown shrimp. In these marsh habitats, shrimp isotopic ratios changed rapidly, suggesting high tissue turnover rates. The study showed that coastal marshes after restoration through the introduction of freshwater inflow may provide feeding habitats favorable for growth and development of juvenile brown shrimp.