Parental dietary effect on embryological development response to toxicants with the sea urchin Arbacia punctulata

Did you consider ammonium? A possible confounding factor in evaluating the toxicity of marine sediments

Bioassays are a crucial tool for assessing environmental quality, but they face inherent variability due to unexplored confounding factors in marine ecosystems. Ammonium (NH4+) is a vital form of nitrogen in aquatic environments, but it is also a significant focus due to its toxic effects, particularly on marine invertebrates. This study examines the impact of ammonium toxicity on Paracentrotus lividus embryo-development bioassays, which are widely used to evaluate the environmental quality of dredged sediment. The aim is to establish threshold values (EC01, EC05, EC20, and EC50 values) for the correct application of the P. lividus bioassay. The research reveals that ammonium has a significant impact on larval development (EC50 for NH4+ equivalent to 0.81 mg/L). The results emphasize the ecological implications of elevated NH4+ levels in dredged material and highlight the need for precise assessments in environmental management. This study provides essential data for refining guidelines and understanding the complex interactions of this compound in marine ecosystems, ensuring accurate evaluations of environmental quality.

TRICAINE METHANESULFONATE (MS-222) SEDATION AND ANESTHESIA IN THE PURPLE-SPINED SEA URCHIN (ARBACIA PUNCTULATA)

The purple-spined sea urchin ( Arbacia punctulata ) is commonly found in shallow waters of the western Atlantic Ocean from the New England area of the United States to the Caribbean. Sea urchins play a major role in ocean ecology, echinoculture, and biomedical research. Additionally, sea urchins are commonly displayed in public aquaria. Baseline parameters were developed in unanesthetized urchins for righting reflex (time to regain oral recumbency) and spine response time to tactile stimulus. Tricaine methanesulfonate (MS-222) was used to sedate and anesthetize purple-spined sea urchins and assess sedation and anesthetic parameters, including adhesion to and release from a vertical surface, times to loss of response to tactile stimulus and recovery of righting reflex, and qualitative observations of induction of spawning and position of spines and pseudopodia. Sedation and anesthetic parameters were evaluated in 11 individuals in three circumstances: unaltered aquarium water for baseline behaviors, 0.4 g/L MS-222, and 0.8 g/L MS-222. Induction was defined as the release from a vertical surface with the loss of righting reflex, sedation as loss of righting reflex with retained tactile spine response, anesthesia as loss of righting reflex and loss of tactile spine response, and recovery as voluntary return to oral recumbency. MS-222 proved to be an effective sedative and anesthetic for the purple-spined sea urchin at 0.4 and 0.8 g/L, respectively. Sodium bicarbonate used to buffer MS-222 had no measurable sedative effects when used alone. Anesthesia was quickly reversed with transfer of each individual to anesthesia-free seawater, and no anesthetic-related mortality occurred. The parameters assessed in this study provide a baseline for sea urchin anesthesia and may provide helpful comparisons to similar species and populations that are in need of anesthesia for surgical procedures or research.

Influence of salinity on fertilization and larval development toxicity tests with two species of sea urchin

Sea urchin embryo-larval development (ELD) and fertilization tests have been widely used in ecotoxicity studies and are included in regulatory frameworks. Biological processes occur naturally within a range of salinity that depends on the species considered. In an attempt to determine the optimum range of salinity, ELD and fertilization bioassays were performed at different salinities (15-40.5‰) with two species of Atlantic sea urchin: Arbacia lixula and Paracentrotus lividus. In the ELD assay, the optimum range of salinity was wider for A. lixula (29-35.5‰) than for P. lividus (29-33‰). In the fertilization assay with P. lividus as a bioindicator species, the highest percentage of fertilization (90%) was obtained at salinities of between 29 and 33‰. More research on A. lixula is required, since the fertilization success was below 60%. The results of the present study demonstrate that salinity may be a confounding factor in interpreting ELD test results.