| Summary |
The purpose of this study was to evaluate the physical effects of monomeric aluminum and acid pH on the epidermis of developing striped bass (Morone saxatilis) larvae. In the laboratory, larvae were placed in replicated test chambers containing synthetic freshwater and three different nominal concentrations of total aluminum (0, 140, 280 [mu]g/L) at three different pH ranges (7.1 - 7.6, 6.1 - 6.6, 5.1 - 5.6). Six larvae from each test group were removed every 12 h over a period of 48 h. Larvae were examined by scanning electron microscopy to determine the amount of surface tissue damage. The skin of test larvae was compared to that of controls which were sacrificed during the course of the experiment. Larval epidermal tissues exposed to high concentrations of aluminum (280 [mu]g/L) at low pH (5.1 - 5.6) exhibited the greatest amount of change when compared to the surface of controls. Scanning electron microscopic analysis also revealed that the mucous cuticle was less pronounced, and eventually disappeared, on the surface of the larvae subjected to high aluminum and low pH. A rapid progression of these anatomical changes was apparent over the 48-h test period. It is possible that these structural changes may affect larval gas and ion osmoregulation; elimination of the mucoid layer may reduce larval defense and movement capabilities. |
