title: Reproduction of the long-spined sea urchin Diadema setosum in the Gulf of Aqaba - implications for the use of gonad-indexes.
abstract: As global warming and climate-change proceeds ever more rapidly, organisms depending on seasonal cues to synchronize reproduction face an unclear future. Reproduction in Diadema setosum in the Gulf of Aqaba (Red Sea) is seasonal, with mature individuals occurring from July to October. Gonad indexes (GI), in contrast, indicate that spawning occurs from August through December and suggests two main spawning events. Histological analysis, however, indicate that the second peak of GI values cannot be related to spawning, but rather correspond to recovering individuals. In Diadema, examination of GI values alone may thus lead to erroneous conclusions. GI was moderately-strong positively correlated with sea-surface temperatures, but not with chlorophyll-a concentrations or photoperiod. Spawning coincides with the onset of the annual chlorophyll-a increase, however, which might be advantageous for nutrition of the developing larvae. First significant GI increase coincides with the shortening of day-length, which may act as a cue for D. setosum gametogenesis. Gametogenesis is highly synchronised between sexes, although the mature phase of females exceeds that of males. The non-complete overlap may represent sampling bias or represent an adaptive strategy for enhancing fertilisation success. Skewed sex ratios (♀:♂ 1:0.59, n = 360) in the Gulf of Aqaba may be related to pollution.
authors.affiliation: Natural History Museum Vienna, Geological-Paleontological Department, Burgring 7, 1010 Vienna, Austria.|The Steinhardt Museum of Natural History, Israel National Center for Biodiversity Studies, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Omri
authors.initials: O
authors.lastname: Bronstein
authors.affiliation: Natural History Museum Vienna, Geological-Paleontological Department, Burgring 7, 1010 Vienna, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Kroh
authors.affiliation: Department of Zoology, The George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv 69978, Israel.
authors.forename: Yossi
authors.initials: Y
authors.lastname: Loya
mesh_terms: D000818:Animals; D005260:Female; D005718:Gametogenesis; D006066:Gonads / Q000166:cytology / Q000502:physiology*; D019156:Indian Ocean; D008297:Male; D009865:Oocytes / Q000502:physiology; D012098:Reproduction; D012617:Sea Urchins / Q000166:cytology / Q000502:physiology*; D012621:Seasons; D012744:Sex Ratio; D013696:Temperature