Meeting Abstract
Hawai’i’s intertidal shorelines are extremely vulnerable to rising ocean temperatures, habitat degradation, and harvesting pressure. In response to these threats, there is a need to understand how reproductive success of resource species is affected by these and other environmental factors. In Hawai’i, there is sustained interest among local communities in developing sustainable management that incorporates reproductive and early life histories of resource invertebrates. This study investigates environmental factors that drive spatial and temporal variation in population densities, egg quality and larval fitness of a culturally and ecologically important Hawaiian species of sea urchin, Colobocentrotus atratus. Urchins were collected from a total of eight populations around O’ahu and Hawai’i Island in the spring and fall spawning seasons. Test diameter and height were recorded and egg volume and per-female fecundity were recorded. Test diameter had no significant effect on egg volume or fecundity across sites, suggesting that body size may not be a good indicator of reproductive output or an important factor in decision-making about regulated harvesting. There were significant differences in fecundity and egg volume between sites and season, as well as significant site-by-season interactions. These data suggest that maternal investment is affected by physical-biological factors on temporal and local scales, and we will investigate these factors by monitoring reproductive seasonality, population densities, algal cover, temperature, and algal nitrogen content at each site over three years. This project will shed light on the environmental drivers of variation in maternal investment and will facilitate sustainable management of Hawai’i’s intertidal environment in the face of harvesting pressure and changing climate.
