Reproductive Synchrony of the Hermatypic Corals, Acropora hemperchii and Pocillopora verrucosa, along the Egyptian Red Sea Offshore and Onshore Reefs: Environmental Constraints

Histological investigations for the reproductive conditions of Acropora hemperchii and Pocillopora verrucosa in the onshore reefs at site 1, which impacted by oil pollution, and site 2 which, impacted by phosphate shipping, and those in the offshore ones at sites 3 and 4 at, respectively, each was impacted by diving activities, were studied. Both of the given species was found to be hermaphrodite broadcast spawners annually. The gonads of P. verrucosa were found on stalks arising from the column wall, but in A. hemperchii, the gonads fill the entire mesenteries. Moreover, there are pronounced differences in the timing and length of gametogenesis and spawning of A. hemperchii and P. verrucosa between different geographic regions. A. hemperchii showed the least productivity at the effected with oil pollution at site 1, represented by 55 % of mature oocytes and an additional 38 % of immature oocytes. P. verrucosa declined to 46 %of mature oocytes and 50 % of immature oocytes. The highest productivity of A. hemperchii was represented by 90 % matures, 3 % immatures and 7 % empty and for Pocillopora verrucosa increased to 92 % matures, 2 % immature, and 5 % empty at the offshore site 2, the site impacted by eutrophication as a result of phosphate shipment. The spawning season of A. hemperchii in the northern Red Sea at site 1, is two months later than in the southern site 2, where A. hemperchii starts spawning in May and extended to July. However, P. verrucosa begins one month early than A. hemperchii at the same site, and extends for three months also from April to June. Moreover, spawning of P. verrucosa at site 2 is one month early than at its spawning at site 1. While, P. verrucosa at sites 3 & amp, amp, 4 starts spawning at April and extended for two months only.