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The majority of published accounts on scleractinian coral reproduction are from the tropical Pacific and Caribbean, with
very little information known about Red Sea species. This report examines variation in reproductive mode in 24 species of
hermatypic corals (belonging to seven families) in the Gulf of Eilat, Red Sea. Eighteen species are hermaphroditic broadcasters,
two are hermaphroditic brooders and three are gonochoric broadcasters. In the Pocilloporidae, the gonads project into the
body cavity, while in the other six families the gonads reside inside the mesenteries. The number of gonads per polyp in broadcasting
species follows family or genus lines. Fecundity (eggs per polyp) increases with polyp size. Brooding species usually exhibit
one or two gonads per polyp and each gonad contains only one to three oocytes. Oocyte size varies widely and does not relate
to mode of reproduction. The largest oocytes (diameter = 450 μm) occur in the brooding coral Alveopora daedalea and in broadcasting species of the genus Acropora (diameter = 420 μm). Gonad morphology and gonochorism versus hermaphroditism appear to be constrained phylogenetically at
the family or genus level. Lastly, this report compares the data presented for Red Sea scleractinian species with the data
available on scleractinian corals from other geographical regions.
Received: 2 February 1993 / Accepted: 9 March 1998 相似文献
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The freshwater amphipod, Hyalella azteca, is widely used in laboratory sediment toxicity and bioaccumulation tests. However, its responses in the laboratory are probably very different from those in the field. A review of the literature indicates that in its natural habitat this species complex is primarily epibenthic, derives little nutrition from the sediments, and responds primarily to contaminants in the overlying water column (including water and food), not sediment or porewater. In laboratory sediment toxicity tests H. azteca is deprived of natural food sources such as algal communities on or above the sediments, and is subjected to constant light without any cover except that afforded by burial into the sediments. Under these constraining laboratory conditions, H. azteca has been reported to respond to sediment or porewater contamination. In nature, contamination of overlying water from sediment is less likely than in the laboratory because of the large, generally non-static sink of natural surface water. H. azteca does not appear to be the most appropriate test species for direct assessments of the bioavailability and toxicity of sediment contaminants, though it is probably appropriate for testing the toxicity of surface waters. Toxic and non-toxic responses will be highly conservative, though the latter are probably the most persuasive given the exposure constraints. Thus H. azteca is probably a suitable surrogate species for determining sediments that are likely not toxic to field populations; however, it is not suitable for determining sediments that are likely toxic to field populations. 相似文献
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Symbiont specificity and bleaching susceptibility among soft corals in the 1998 Great Barrier Reef mass coral bleaching event 总被引:1,自引:0,他引:1
Considerable variability in bleaching was observed within and among soft coral taxa in the order Alcyonacea (Octocorallia:
Cnidaria) on the central Great Barrier Reef (GBR, latitude 18.2°–19.0°S, longitude 146.4°–147.3°E) during the 1998 mass coral
bleaching event. In April 1998, during a period of high sea surface temperatures, tissue samples were taken from bleached
and unbleached colonies representative of 17 soft coral genera. The genetic identities of intracellular dinoflagellates (Symbiodinium spp.) in these samples were analyzed using PCR-denaturing gradient gel electrophoresis fingerprinting analysis of the internal
transcribed spacer regions 1 and 2. Alcyonaceans from the GBR exhibited a high level of symbiont specificity for Symbiodinium types mostly in clade C. A rare clade D type (D3) was associated only with Clavularia koellikeri, while Nephthea sp. hosted symbionts in clade B (B1n and B36). Homogenous Symbiodinium clade populations were detected in all but one colony. Colonies that appeared bleached possessed symbiont types that were
genetically indistinguishable from those in nonbleached conspecifics. These data suggest that parameters other than the resident
endosymbionts such as host identity and colony acclimatization are important in determining bleaching susceptibility among
soft corals.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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