Núñez Flores Mónica, Rodríguez-Quintal José Gregorio, Cristina Díaz María
Departamento de Biología, Facultad de Ciencias y Tecnología, Apartado 2005, Universidad de Carabobo, Valencia, Venezuela.
Rev Biol Trop. 2010 Oct;58 Suppl 3:175-87.
Sponges constitute one of the most diverse and abundant animal groups in the marine tropical benthos especially in coral reefs, though poorly studied to species level. The aim of this study is to characterize the sponge community along a depth gradient at Isla Larga (Parque Nacional San Esteban, Venezuela) fringe reef. Net and total sedimentation, roughness index, sponge species richness, density and proportion of the bottom covered by sponges, were evaluated at seven depths (1, 3, 6, 9, 12, 15, 18 m), 17 species were identified grouped in 10 demosponges families. The highest densities and coverage corresponded to 6 m of depth (6.03ind/m2; 11%), that coincides with the lowest net sedimentation and highest substrate heterogeneity. Most abundant species were Desmapsamma anchorata, Amphimedon erina and Scopalina rueztleri. Principal component analysis divided this community in three zones according to depth. The shallow zone of the reef (1 and 3 m), where wave force and high irradiance exert a constant stress sponges, shows the lowest density and coverage by sponges. In contrast, medium depth (6, 9 y 12 m) and deep zone (15 y 18 m) with lower light and sedimentation levels seem to enhance sponge growth and survival that are reflected on the higher densities and coverage of sponges.
海绵动物是海洋热带底栖生物中最多样化且数量丰富的动物群体之一,尤其是在珊瑚礁中,不过在物种层面上的研究还很匮乏。本研究的目的是描述委内瑞拉圣埃斯特万国家公园伊斯拉拉尔加边缘珊瑚礁沿深度梯度的海绵动物群落特征。在七个深度(1米、3米、6米、9米、12米、15米、18米)评估了净沉降量和总沉降量、粗糙度指数、海绵物种丰富度、海绵的密度以及海绵覆盖底部的比例,共鉴定出17个物种,分属于10个寻常海绵纲科。最高密度和覆盖率出现在6米深度处(6.03个/平方米;11%),这与最低的净沉降量和最高的底物异质性相吻合。最丰富的物种是锚状网纹海绵、埃氏双耳海绵和鲁氏斯科普海绵。主成分分析根据深度将这个群落分为三个区域。珊瑚礁的浅水区(1米和3米),海浪作用力和高光照强度对海绵持续施加压力,海绵的密度和覆盖率最低。相比之下,光照和沉降水平较低的中深度区(6米、9米和12米)和深水区(15米和18米)似乎促进了海绵的生长和存活,这体现在海绵更高的密度和覆盖率上。