| I used field experiments to test the effects of predation risk by gulf flounder (Paralichthys albigutta) on juvenile pinfish ( Lagodon rhomboides) growth rates by measuring changes in length and weight and RNA-DNA ratios in three habitats (sand, low density, and high density seagrass, Halodule wrightii). Standardized differences of length and weight showed that pinfish inhabiting seagrass habitats displayed the fastest growth rates in the beginning of the growing season (June) and those in sand had the fastest growth rates later in the season (August to October). This can be attributed to two factors. First, the larger pinfish at the end of the season may have been more inhibited by high density grass, thereby reducing foraging efficiency. Secondly, analysis of pinfish gut contents showed that in October, pinfish in sand and low density of Halodule were feeding primarily on fish, while those in high density grass fed primarily on plant material, which most likely supports a lower growth rate compared to fish. (Abstract shortened by UMI.)... |
