PS 24-48 - CANCELLED - Hypoxia in a tropical estuary

Background/Question/Methods

Climate change-driven hypoxia is an increasing phenomenon occurring in coastal and estuarine waters with a great impact on broad socioeconomic and environmental spheres such as marine and coastal ecosystems, fisheries, tourism, food safety and even human health, among many others. However, this is poorly documented in estuaries of Colombia due to the lack of systematic data collection and the availability of observed data to establish historical changes in dissolved oxygen. Here we used 10 years of observed data (2001-2011) to report for the first time the unprecedented occurrence of hypoxia in the widespread estuaries (i,e Gulf of Urabá) located in the southwest Caribbean Sea, Colombia (South America).

Results/Conclusions

We found that this estuary has presented about 55 events of hypoxia ( < 2 mg/L OD) but 7 anoxic ones (i.e. 0 mg/L OD) during the decade 2001-2011. Also, non-significant trends in dissolved oxygen were observed over a decade (+0.224 mg/L OD, p-value > 0.10), but seasonal differences were found between the dry (-0.429 mg/L OD, p-value > 0.10) and rainy (+1.083 mg/L OD) seasons, being the last significant at p < 0.10. We hypothesize that the effect of the increasing chemical nutrient runoff from nearby tributaries (i.e Atrato river) and human actions (such as banana plantations) in the area may be behind the growing deoxygenation, especially during the dry season.



One of the consequences of the deoxygenation is the so-called dead zones with repercussions throughout the ecosystems in the water column, bottom and marine biota. However, the lack of oxygen is one of the most deleterious effects on this tropical ecosystem. There is a need to develop and implement new oxygen observatories that improve monitoring and management strategies for coastal hypoxia in this region.