Assessing the effect of oil spills on the dynamics of the microbial plankton community using a NPZD model

A mesocosms approach was used to assess the seasonal variability and the effect of oil spills on the structure and dynamics of marine microbial plankton communities in a coastal upwelling system. To this aim, four experiments were conducted during the main characteristic periods of the seasonal cycle in the Ria de Vigo (NW of Spain): spring phytoplankton bloom, summer stratification, autumn upwelling and winter mixing. In each of these experiments, enclosed communities in control and oiled bags were monitored and key variables and rates were measured during 9 days. Temporal changes in community structure and function were interpreted applying a simple NPZD (Nutrients-Phytoplankton-Zooplankton-Detritus) model in which the strategy was to maintain invariant as many model parameters as possible. The analysis of those parameters that were modified to accurately simulate the time evolution of the microbial communities in the mesocosms, provided important information about the main processes influencing the plankton community structure and dynamics in the bags as well as about the effect of oil. This modelling approach allowed assessing the dynamics of the four communities just varying phytoplankton maximum growth rates, bacterial growth efficiencies, microzooplankton grazing rates and phytoplankton sinking rates. Comparison of parameters in control and oiled bags in each period allowed to infer the negligible effect of oil spills on the structure and dynamics of the microbial plankton communities in this coastal upwelling system.

Automated summary

This study used a mesocosms approach to assess the seasonal variability and the effect of oil spills on the structure and dynamics of marine microbial plankton communities in a coastal upwelling system. The results showed that oil spills had negligible effects on the plankton community structure and dynamics in this system.