摘要
本文研究了有关坦桑尼亚珊瑚礁环境不同方面的类珊瑚虫(刺胞动物门,珊瑚虫纲)的分布和丰度。通过设线截距横切和点取标技术,调查了受到人类不同骚扰程度的5种礁。下列的礁石内,不同栖息地中的类珊瑚虫的生长和其底质的构成:礁坪内部和中部,礁脊,礁坡上2m和4m处,类珊瑚虫存在所有的礁上,并认定了5个种类:Rhodactisrhodostoma,R.mussoides,Ricordea yuma,Actinodiscus Unguja和A.nummiforme,而在所有地方,R.rhodostoma占有优势。在礁内浅水的栖息地里,R.rhodostoma具有极高的密度。R.rhodostoma存在于所有的栖息地,而其他的类珊瑚虫并不是均匀的分布的。在现存生物覆盖物里,类珊瑚虫所占百分比在石珊瑚之后名列第二。本文研究的结果表明,跟其他固着生物相比,类珊瑚虫得益于骚扰,他们喜欢栖息在有死礁、岩石和碎屑的地区而避开浮珊瑚。类珊瑚虫的分布率与水的混乱程度有着相关关系,这些类珊瑚虫在受扰动较大的礁区占优势,即受到营养物和渔业影响的礁区。
This study examined the distribution and abundance of corallimorpharians (Cnidaria, Anthozoa) in Tanzania in relation to different aspects of the coral reef environment. Five reefs under varying degrees of human disturbance were investigated using the line intercept transect and point technique. Corallimorpharian growth and the composition of the substratum were quantified in different habitats within reefs: the inner and middle reef flat, the reef crest, and at the 2 and 4 m depths on the reef slope. Corallimorpharians occurred on all the reefs and 5 species were identified: Rhodactis rhodostoma, R. mussoides, Ricordea yuma, Actinodiscus unguja and A. nummiforme. R. rhodostoma was the dominant corallimorpharian at all sites. Within reefs, they had the highest densities in the shallow habitats. While R. rhodostoma occurred in all habitats, the other corallimorpharian species showed uneven distributions. Corallimorpharians ranked second, after scleractinian coral, in percent living cover. Results from this study suggested that corallimorpharians benefitted from disturbance compared with other sessile organisms. They preferred inhabiting areas with dead coral, rock and rubble whilst live coral was avoided. There was a positive relationship between percent cover of corallimorpharians and water turbidity and they dominated the more disturbed reefs, i.e. reefs that were affected by higher nutrient loads and fishing.
