Rotenone Decreases Hatching Success in Brine Shrimp Embryos by Blocking Development: Implications for Zooplankton Egg Banks.

While many zooplankton species recover quickly after the treatment of water resources with the piscicide, rotenone, some fail to reach pretreatment population density or, in rare cases, do not reappear at all. The variable impact of rotenone on zooplankton populations could stem from differences in the capacity of species to switch entirely to anaerobic catabolic pathways in the presence of rotenone, which blocks mitochondrial electron transport. Alternatively, variable responses among species could originate from differences in permeability of dormant life-stages to lipophilic chemicals like rotenone. The purpose of the present study was to determine the effects of rotenone on development, emergence and hatching of zooplankton embryos that lack both the anaerobic capacity to develop in the presence of rotenone and a permeability barrier to prevent the entry of rotenone during dormancy. Post-diapause embryos of the brine shrimp, Artemia franciscana, were employed as a model system, because they are permeable to lipophilic compounds when dechorionated and require aerobic conditions to support development. Early development in this species is also well characterized in the literature. Brine shrimp embryos were exposed to rotenone while development was either slowed by chilling or suspended by anoxia. Development, emergence and hatching were then observed in rotenone-free artificial seawater. The data presented demonstrate that rotenone freely diffuses across the embryonic cuticle in a matter of hours, and prevents development and emergence after brief exposures to ecologically relevant concentrations (0.025-0.5 mg L-1) of the piscicide. Neither the removal of rotenone from the environment, nor the removal of embryonic water with a hypertonic solution, are sufficient to reverse this block on development and emergence. These data indicate that rotenone could impair recruitment from egg banks for species of zooplankton that lack both an embryonic barrier to the entry of lipophilic compounds and the anaerobic capacity to develop when NADH:ubiquinone oxidoreductase activity is inhibited by rotenone.

Nutritional quality of foods marketed to children in Honduras.

Evidence suggests that exposure to advertising of unhealthy foods may contribute to increased rates of obesity in children. This study examined the extent to which television stations marketed unhealthy foods to children during after-school programming aired over one week in La Ceiba, Honduras. Content analysis was performed on four television stations, including one broadcast station and three cable networks. Eighty hours of programming were recorded and analyzed. Advertised products were categorized as food or non-food items, with food items further classified as healthy or unhealthy. Advertisements were coded as those aimed at children, adults, or both, and chi-square tests were used to compare the proportion of unhealthy advertisements by target audience. A total of 2271 advertisements aired during the observation period, with 1120 marketing products (49.3%). Of those, 397 (35.4%) promoted foods-30.2% were for healthy foods and 69.8% for unhealthy foods. The unhealthy foods were all advertised on cable networks and not the broadcast station. Children appeared to be targeted more than adults in advertisements for unhealthy foods (92.1%, p<0.001). Cable television programming during after-school hours advertised primarily unhealthy foods. Exposure to these advertisements may promote consumption of unhealthy foods by children, increasing their risk of obesity.