SETTLEMENT OF CROWN-OF-THORNS STARFISH - ROLE OF BACTERIA ON SURFACES OF CORALLINE ALGAE AND A HYPOTHESIS FOR DEEP-WATER RECRUITMENT
SETTLEMENT OF CROWN-OF-THORNS STARFISH - ROLE OF BACTERIA ON SURFACES OF CORALLINE ALGAE AND A HYPOTHESIS FOR DEEP-WATER RECRUITMENT
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DOI：
10.3354/meps071143
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发表时间：
1991-04-01
影响因子：
2.5
通讯作者：
GIDDINS, R
中科院分区：
文献类型：
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作者：
JOHNSON, CR;SUTTON, DC;GIDDINS, R
定居试验进行的棘冠海星的幼虫，草履虫planci揭示了适度的基层特异性。最高的定居和变态率发生在珊瑚碎石和甲壳珊瑚礁（CCA）Lithothamalphiposorum，但利率更多变的珊瑚。解释碎石上的沉降是困难的，因为碎石总是支持一些CCA。其他CCA（Porolithon onkodes和Neogoniolithon fosley），非钙质甲壳红藻（Peyssonellia sp.），还有脏瓷砖这些结果是一致的，无论幼虫是否提供了一个选择的基质或没有。当幼虫从L. pseudosorum通过网格，沉降是高度可变的，但有时发生在高速率，这表明与藻类接触不是强制性的诱导。幼虫没有诱导解决GABA（γ-氨基丁酸），升高的K+浓度，或珊瑚块污染9天，和结算率几乎为零，在控制没有已知的添加诱导剂。高诱导性L. pseudosorum的诱导活性较低，说明抗生素对A. planci L.假孢子囊菌可能是由附生细菌介导的。其他结果与细菌介导诱导的概念一致。不同部位对L. pseudosorum植物变化很大，植物表面的细菌密度也是如此。幼虫总是定居在具有高密度的细菌的叶状体的部分，但从来没有在邻近地区的附生细菌稀疏。诱导刺激可能是化学物质，因为它是通过煮沸或高压灭菌灭活的，并且可能是相对较大的分子，因为它在诱导藻类或珊瑚碎石的水、乙醇或氯仿提取物中未检测到，并且被孔径为10 000道尔顿的透析管保留。研究了珊瑚碎石和L. GBR中陆架礁上及其周围的假孢子菌、礁周围水动力滞留细胞的位置以及GBR上爆发的模式表明，A.浮游生物更可能出现在深水中而不是浅水中。这可以解释A. GBR上的浮游生物并不预示着浅水中幼鱼丰度的增加，而是首先观察到成年海星从深水中上升。戴维斯礁的初步深水视频断面显示，碎石和CCA丰富的深水（30至65米）附近的区域，成年海星的聚集，第一次看到移动从深水，但底层在深水关闭其他部分的珊瑚礁是沙子。
Settlement trials conducted with larvae of crown-of-thorns starfish Acanthaster planci revealed a moderate degree of substratum specificity. Highest rates of settlement and metamorphosis occurred on coral rubble and the crustose coralline alga (CCA) Lithothamnium pseudosorum, but rates were more variable on the coralline. Interpretation of settlement on the rubble is difficult because rubble always supported some CCA. Settlement was significantly lower on other CCA (Porolithon onkodes and Neogoniolithon foslei), non-calcareous crustose red algae (Peyssonellia sp.), and fouled ceramic tiles. These results were consistent irrespective of whether larvae were offered a choice of substrata or not. When larvae were separated from L. pseudosorum by mesh, settlement was highly variable but sometimes occurred at high rates, suggesting that contact with the algae is not obligatory for induction. Larvae were not induced to settle by GABA (gamma-amino butyric acid), elevated K+ concentrations, or coral blocks fouled for 9 d, and settlement rates were virtually zero in controls without a known added inducer. Treatment of highly inductive shards of L. pseudosorum with antibiotics reduced their inductive activity to low levels, suggesting that induction of settlement and metamorphosis of A. planci by L. pseudosorum may be mediated by epiphytic bacteria. Other results were consistent with the notion of bacteria-mediated induction. The inductive ability of different regions on individual L. pseudosorum plants varied greatly, as did densities of bacteria on the plant surface. Larvae always settled on sections of thallus having high densities of bacteria, but never on adjacent areas where epiphytic bacteria were sparse. The inductive stimulus is likely to be chemical since it was inactivated by boiling or autoclaving, and may be a relatively large molecule since it was not detected in water, ethanol or chloroform extracts of inductive algae or coral rubble, and was retained by dialysis tubing of pore size 10 000 Daltons. The spatial distribution of coral rubble and L. pseudosorum on and around GBR midshelf reefs, the location of hydrodynamic retention cells around reefs, and the pattern of outbreaks on the GBR, suggest that mass settlements of A. planci are more likely to occur in deep than in shallow water. This would explain the paradox that outbreaks of A. planci on the GBR are not heralded by increases in abundances of juveniles in shallow water, but are first observed as adult starfish ascending from deepwater. Preliminary deep water videotransects off Davies Reef showed that rubble and CCA were abundant in deep water (30 to 65 m) adjacent to the area where aggregations of adult starfish were first seen moving up from deep water, but the substratum in deep water off other sections of the reef was sand.