Coral reefs are declining worldwide due to both natural and anthropogenic factors. The global threats on reefs are synergistic. Some of reef threats are preventable such as fishing, while others such as coral bleaching and coral diseases are not. Thus is important focus on managing factors that can prevented, while understanding the synergistic relationships between them. The substratum categories and fish fauna data, was collected using underwater visual census (UVC) and line intercept transect (LIT) respectively based on Hill & Wilkinson 2004.The data spans four years (2004, 2005, 2006 and 2008) and was collected between March-April (monsoon transitional period) every year. Data analysis was done primarily by Plymouth Routines in Multivariate Ecological Research (PRIMER 6.1.13) software. Routines Principal Component Analysis (PCA), Non-Metric Multidimensional Scaling(MDS), Similarity Profile (SIMPROF), Analysis of Similarity (ANOSIM) and Non-parametric regression (LINKTREE) were employed in data analysis. The reef at the study area is algae dominated. Herbivores and detrivores are the dominant trophic groups. Fisheries interactions and natural nutrient loading are influential at the local context. The relationship between substratum categories and fish fauna is ecologically significant. Substratum categories and fish fauna vary significantly spatially, temporally and across sectors. However their variation show an inverse relationship across reserve and zones. The outer reef is influential across substratum categories and fish fauna assemblages. Spatial variation of substratum categories is strongly influenced by algae (fleshy algae, halimeda and algae turf) soft corals and hard coral. Fish fauna spatial variation is largely defined by; planktivores, detritivores, herbivores, piscivores and invertivores. Consequently the study surmises that phase shift has not occurred, however it may occur soon if fisheries interactions are not sustainably managed. The study emphasises that reef food web integrity and fish herbivory are important in the maintaining the coral-algae balance. The study underscores that fishing and not eutrophication is influential in driving phase shifts in many reefs worldwide although the synergistic interactions are salient. |
