Seasonal Changes in Gonad Index, Biochemical Composition and Heavy Metal Determination of Sea Urchin Paracentrotus lividus Gonads from the South Coast of Morocco

Seasonal variations of the gonad index (GI), the biochemical composition, and the concentration of heavy metals in the gonads of the sea urchin, Paracentrotus lividus (Echinodermata: Echinoidea), were determined. Samples were collected from three sites in the Agadir region: Cap Ghir, Sidi R’bat and Anza (south coast of Morocco) between March 2018 and February 2020. This study highlights the point that at the three study sites, the gametogenic cycle of the sea urchin was annual, with a long, single spawning (spring–summer) for both cycles. Protein constituted the main component of the gonad which ranged between 23.73 and 8.11 mg/mL, while lipid and carbohydrate were also found in considerable amounts. The maximum levels of proteins in the gonad coincided with the highest GI values, there being evidence of gonad protein requirements during gametogenesis. Heavy metals (Cu, Pb, and Cd) were present with very low values and this reflects the health of the Coastal ecosystem of Cap Ghir and Sidi R'bat. For Anza, we noticed higher values than the other sites, due to the presence of industries and urban development.