Impact of yellowtail kingfish (Seriola lalandi Valenciennes) mariculture on the macrobenthic community at Magdalena Bay, Baja California Sur, Mexico

The goal of this study was to evaluate the effect of organic waste from yellowtail kingfish (Seriola lalandi) mariculture on seafloor sediments in Magdalena Bay, Baja California Sur. For the spatial analysis of the benthic macroinvertebrate community, sediment samples were collected below the cage and control areas in 2017. Sandy sediments predominated in the study area; organic matter content ranged from 0.96% to 1.18%, except for the control zone III, where it reached 1.48%. Total nitrogen and total phosphorus concentration showed significant differences between cage and control areas. A total of 63 benthic families were identified, and the highest density corresponded to polychaete annelids. BOPA index values indicate a low disturbance level in the study area; however, the distribution of benthic abundance shows a clear separation between zones, related to differences in total phosphorus and total nitrogen contents. The results obtained indicate that the fish farm generated a spatial differentiation of the benthic macroinvertebrate community, although organic farm waste has had a low impact on the seafloor. Results also show that benthic macrofauna is a good ecological indicator and that benthic indices provide a useful tool to evaluate environmental quality.