Monitoring the effects of spatial protection on the reef fish communities of the Pondoland Marine Protected Area, Eastern Cape Province, South Africa

Abstract

Monitoring marine protected areas (MPAs) is critical for evaluating their effectiveness and for improving management. In this study, a single-camera baited remote underwater video system (mono-BRUVS) was deployed quarterly at four sites (10–30-m depths) to quantify the reef fish communities in protected (no-take) and adjacent exploited areas of the Pondoland MPA on the east coast of South Africa (Indian Ocean). To assess size (biomass) of the fish communities, we used 10 years of research linefishing data (2006–2016) from the same areas. Univariate and multivariate analyses were used to compare abundance and biomass of the fish communities between protected and exploited areas. Significant differences were detected between fish communities in protected and exploited areas based on their abundance and biomass. These differences are primarily ascribed to linefishing and the removal of larger, predatory species such as yellowbelly rockcod Epinephelus marginatus, Scotsman Polysteganus praeorbitalis and black musselcracker Cymatoceps nasutus in the adjacent exploited areas. Removal of such predators may have caused trophic cascading or prey release, resulting in very different fish communities. These results highlight the importance of investigating the entire fish community and not only target fishery species when evaluating MPA effectiveness.

Keywords:

• abundance
• baited remote underwater video
• biomass
• ecological effectiveness
• exploited area
• no-take area
• research linefishing
• trophic cascade