Spatial heterogeneity of coral reef benthic communities in Kenya.

David Obare Obura,Chaolun Allen Chen,Jose M Riascos,Juliet Furaha Karisa

doi:10.1371/journal.pone.0237397

Abstract

Spatial patterns of coral reef benthic communities vary across a range of broad-scale biogeographical levels to fine-scale local habitat conditions. This study described spatial patterns of coral reef benthic communities spanning across the 536-km coast of Kenya. Thirty-eight reef sites representing different geographical zones within an array of habitats and management levels were assessed by benthic cover, coral genera and coral colony size classes. Three geographical zones were identified along the latitudinal gradient based on their benthic community composition. Hard coral dominated the three zones with highest cover in the south and Porites being the most abundant genus. Almost all 15 benthic variables differed significantly between geographical zones. The interaction of habitat factors and management levels created a localised pattern within each zone. Four habitats were identified based on their similarity in benthic community composition; 1. Deep-Exposed Patch reef in Reserve areas (DEPR), 2. Deep-Exposed Fringing reefs in Unprotected areas (DEFU), 3. Shallow Fringing and Lagoon reefs in Protected and Reserve areas (SFLPR) and 4. Shallow Patch and Channel reefs (SPC). DEPR was found in the north zone only and its benthic community was predominantly crustose coralline algae. DEFU was found in central and south zones mainly dominated by soft corals, Acropora, Montipora, juvenile corals and small colonies of adult corals. SFLPR was dominated by macroalgae and turf algae and was found in north and central zones. SPC was found across all geographical zones with a benthic community dominated by hard corals of mostly large colonies of Porites and Echinopora. The north zone exhibits habitat types that support resistance properties, the south supports recovery processes and central zone acts as an ecological corridor between zones. Identifying habitats with different roles in reef resilience is useful information for marine spatial planning and supports the process of designing effective marine protected areas.

Highlights

Coral reefs are among the most biodiverse ecosystems in the world [1], providing an array of ecological services which are important for human well-being [2, 3]
The observed differences in benthic community composition among geographic zones found in this study is consistent with previous authors that have documented the biogeographic distribution of reef-building corals [37, 16]
This area is known to have a high diversity of corals mainly due to its proximity to the Western Indian Ocean (WIO) center of biodiversity which has been documented to be around the northern Mozambique channel (NMC) [37, 16]

Summary

Introduction

Coral reefs are among the most biodiverse ecosystems in the world [1], providing an array of ecological services which are important for human well-being [2, 3]. The interaction of the EACC and the SC in the north creates a marginal, high-latitude and upwelling system with transitioning communities from the East African to Somali-Arabian fauna [16]. This results in high coral species diversity in the southern parts of Kenya and a decrease in diversity towards the north [16]. The presence of river systems in the central-northern region introduces small-scale influences in species distribution by creating environmental barriers that further limit the transport of larvae to the north [17]

Methods

Results

Conclusion