Natural and anthropogenic-induced stressors affecting the composition of fish communities on the rocky reefs of Ecuador

Natural and human-induced stressors have threatened the sustainability of the fish communities of coral-rocky reefs worldwide in the last decades. The composition of the fish communities on the reefs of Ecuador and the factors affecting spatiotemporal changes are unknown. We studied the influence of the descriptors of structural complexity, the current status of coral and human-induced variables over fish communities. A video transect method was used to assess fish communities in three zones (slope, crest, and bottom) of two reefs during two seasons (rainy and dry). The structure of fish communities was highly influenced by the zones and season; rugosity and live coral affected the fish composition on the crest and slope zones. The fractured coral and derelict fishing gear on coral produced an adverse effect on fish composition over the crest. A multifactorial process causing loss of structural complexity and affecting fish composition was identified, however, periodical assessment is required for a greater understanding of this process. [Display omitted] •Differences in the fish composition between the study sites, zones and seasons.•High presence and prevalence of derelict fishing gear.on the coral colonies on the crests.•Negative effects over fish composition in relation to derelict fishing gear and fractured coral.•Spatial and temporal changes in fish communities driven by a multifactorial degradation process.•Evidence of a possible major threat of habitat degradation to coral-dependent fish populations.