Einfluss des Substrat-Neigungswinkels auf die Hartsubstratlebensgemeinschaft im Comau Fjord, Chile
The substratum of the Chilean fjord region features a huge variety of inclination angels. In this study the impact of substrates inclination angles and exposition on hard-bottom assemblages is examined. On top the characteristics of abiotic parameters such as light intensity, current velocity and sedimentation rate at distinct angles have been observed. This study revealed differences in community structure at distinct inclination angles. Multivariate analyses showed clusters of similar assemblages. A photo census-analysis demonstrated that Bryozoa mainly settle on overhanging and sheltered substrate, while Octocorallia are more abundant at steep exposed surfaces. Rhodophyta are most abundant at horizontal exposed substrate, while Chaetopteridae colonize mainly horizontal sheltered surfaces and Serpulidae vertical substratum. The observed distinct structures may be caused by distinct habitats at different inclinations arised from a variation in abiotic parameters. Horizontal substrata are characterized by highest light intensity, decreasing towards overhanging substrata, obviously higher light intensities were measured at exposed compared to sheltered surfaces. There is no evidence indicating differences in current velocity in relation to substrate inclination. Highest sedimentation rates were observed at sheltered horizontal surfaces. This variation of abiotic parameters presumably effects species composition. As a result distinct communities form at different inclination angles due to different preferences on the amount of light intensity and sedimentation rate and differences in competiveness.