Reproductive patterns in meiobenthic Harpacticoida (Crustacea, Copepoda) of the California continental shelf (Santa Maria Basin)

The abundance, life-history characteristics (developmental stage and body size) and reproductive parameters (clutch volume and egg diameter) of three dominant meiobenthic harpacticoid copepod species (Cletodes tuberculatus, C. macrura and Zosime pacifica) in the Santa Maria Basin (California continental shelf) were examined. Comparisons were made temporally (eight quarterly sampling dates in 2 years), and spatially on both local (0–10 km) and regional (20–40 km) scales. Cletodes tuberculatus attained its highest densities in January 1987 and February 1988, while C. macrura were most abundant in May 1987, with no similar maximum in 1988. Zosime pacifica densities were highest between October and April in all years. All three species were most abundant at depths <169 m. High proportions of juvenile copepodites and high sex ratios (female:male >62;1) were observed for all three species, indicating adequate conditions for population growth. However, gravid females were confined to shallow (<169 m) depths. Reproductive parameters exhibited weak relationships to female body size, suggesting a strong environmental influence on reproduction. The three copepod species had different temporal and spatial patterns in reproductive parameters. Reproductive parameters of C. macrura did not vary temporally or spatially. There were small differences in reproductive parameters for Z. pacifica, but with no detectable pattern. Variations in reproductive parameters of C. tuberculatus were related to sediment organic carbon content. Larger clutch volumes and egg diameters of C. tuberculatus were found in the northern portion of the basin, where sediment organic carbon content was highest.