Harmful algal blooms and eutrophication along the mexican coast of the Gulf of Mexico large marine ecosystem
Harmful algal blooms (HABs) have been the subject of many reports released by Mexican Federal Authorities along the Mexican Coast of the Gulf of Mexico Large Marine Ecosystem (MC-GoM-LME), but extensive research that delves deeply into this issue is lacking. Although Karenia brevis blooms have appeared in all Mexican states (except Quintana Roo) and blooms of Cladophora spp., Chattonella marina, Chattonella subsalsa, Glenodinium pseudostigmosum and Chaetoceros holsaticus are fairly new to the MC-GoM-LME, their spatial and temporal variations are largely unknown. It appears that anthropogenic nutrient over-enrichment is the main driver of eutrophication along the MC-GoM-LME. Trophic conditions based on physicochemical parameters, phytoplankton and submerged aquatic vegetation along the northern coast of Yucatan show the influence of Gulf of Mexico LME and Caribbean Sea LME waters, seasonal upwelling and polluted inputs from submarine groundwater discharges. Meso-eutrophic and oligo-mesotrophic conditions on the coast are associated with human activities such as domestic sewage discharges from septic tanks, harbor effluents and brackish waters from artificial inlets. Coastal lagoons in Veracruz have been impacted by urbanization expansion leading to wastewater discharges, fertilizer runoff and changes in land use. Overall, trophic conditions in Veracruz have improved relative to historic trophic index values. At least for the Yucatan State and the Quintana Roo State, there are sites that appear to link the occurrence of HABs and anthropogenic eutrophication. Additional research over inshore, estuarine, coastal and offshore environments requires future monitoring efforts and collaboration with the international community (especially the U.S.).