Oceanic primary production trend patterns along coast of Ecuador

Abstract

ABSTRACT Primary productivity (PP) is a vital oceanographic process generated by photoautotrophic organisms that transform inorganic carbon into organic macronutrients and micronutrients via photosynthesis. While in situ studies have shed light onto the spatial and seasonal variations of chlorophyll a (Chl a) concentration, and thus PP, in specific study sites, there are no comprehensive monitoring programs to assess its long-term variation nor its seasonal patterns in broader areas of coastal Ecuador. The main objective of the present study is to evaluate changes in Chl a concentration along the coast of Ecuador and examine how these changes correspond to changes in Sea Surface Temperature (SST). Eighteen offshore and nearshore sampling sites along the Ecuadorian coast were studied over 15 years, using satellite measurements of MODIS-Aqua and MUR. Results show mean Chl a concentration in coastal Ecuador is rather low (1.5 mg m−3) in comparison with other oceanic regions. Puerto Bolivar, Gulf of Guayaquil and Esmeraldas were characterized by the highest mean Chl a concentration; while Galera San Francisco Marine Reserve, Cojimies and Cabuyal were characterized by the lowest. A positive trend in Chl a concentration was detected at the southernmost (Puerto Bolivar and Gulf of Guayaquil) and northernmost (Esmeraldas) study sites, with a seasonal trend following the observed seasonal SST trend. Chl a is high in areas under the influence of both the Humboldt upwelling system and river discharge. The positive correlation between Chl a and SST is likely a response to increased precipitation during warmer months. These results highlight the importance of improving our understanding of the effects of climate change on coastal PP, and the potential for these effects to influence the health of commercial and threatened marine species. Further research should assess the implications of changes in PP and SST for species of commercial and conservation importance along the coast of Ecuador.