Effects of temperature, feeding and acridine on development and mortality of eggs and nauplh of Diaptomus clavipes schacht

Abstract

The effects of acridine on mortality and development of the freshwater calanoid copepod, Diaptomus clavipes, were measured at temperatures of 16°C, 21°C and 26°C for both fed and unfed animals. Eggs and first instar nauplii were exposed to six concentrations of acridine (0.32–5.6 mg · l −1) in two experiments (egg to second naupliar stage, first naupliar to first copepodid stage) in a static-renewal system and observed for egg development, percent egg hatch, naupliar development and mortality. Acute toxicity (median lethal concentrations - LC 50s) based on mortality from egg to second naupliar stage, increased with increasing temperature while toxicity based on mortality from the first naupliar to first copepodid stage was unaffected by temperature. No animals survived to the second naupliar stage at an acridine concentration of 5.6 mg · l −1. Unfed nauplii died faster with increasing temperature and few (<50%) survived to the first copepodid stage. Rates of egg and naupliar development increased with temperature. However, rates of egg development were unaffected by acridine. Percent egg hatch was unaffected by either temperature or acridine exposure. The effects of acridine on rates of naupliar development, however, were dependent on both temperature and developmental stage. Acridine exposure increased rates of naupliar development at all temperatures tested. Development times (first naupliar to first copepodid stage) in unfed controls were significantly longer (74%, 46%, and 56% at 16°C, 21°C, and 26°C, respectively) than in fed controls.