title: Reducing nutrient impacts from shrimp effluents in a subtropical coastal lagoon.
abstract: Shrimp farm aquaculture causes environmental impacts, notably decreased water quality due to the release of nutrient-rich effluents. Pond wastewater is usually discharged without treatment, and tidal conditions are not taken into account in the management plans. However, natural variability of nutrients makes difficult field evaluation and attribution of impacts. Here we implemented a three-dimensional coupled hydrodynamic-biogeochemical model (spatial resolution=50m×50m, time resolution=4s) in order to evaluate the dispersion conditions under specific tidal conditions of nutrient discharges from a semi-intensive shrimp farm during spring and neap tide. Ammonia was quickly assimilated by plankton and its concentration recovered initial levels 10days after the beginning of the harvest. Due to the higher salinity of the pond effluents, shrimp farm discharges accumulate in waters and sediments of the upper lagoon creeks, mostly affecting the benthos, thus implying a potential risk of shrimp farm self-contamination. Maximum concentrations of most biogeochemical tracers occurred when the harvest ends and the ponds are fully emptied. We show that maximum nutrient concentrations can be reduced by ~10% when the harvest ends during spring tides compared to harvests ending during neap tides. This work may be useful to improve the management of shrimp farm effluents by reducing, easily and at little cost, nutrient impacts on tropical and sub-tropical receiving ecosystems.
authors.affiliation: CONACYT - Estación el Carmen, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Carretera Carmen-Puerto Real km. 9.5, 24157 Ciudad del Carmen, Campeche, Mexico.
authors.forename: José-Gilberto
authors.initials: JG
authors.lastname: Cardoso-Mohedano
authors.affiliation: National Oceanography Centre, Southampton SO14 3ZH, UK.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Bernardello
authors.affiliation: Departamento Procesos Oceánicos y Costeros, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 Ciudad de México, Mexico. Electronic address: jasanchez@cmarl.unam.mx.
authors.forename: Joan-Albert
authors.initials: JA
authors.lastname: Sanchez-Cabeza
authors.affiliation: Unidad Académica Mazatlán, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, 82000 Mazatlán, Sinaloa, Mexico.
authors.forename: Federico
authors.initials: F
authors.lastname: Páez-Osuna
authors.affiliation: Unidad Académica Mazatlán, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, 82000 Mazatlán, Sinaloa, Mexico.
authors.forename: Ana-Carolina
authors.initials: AC
authors.lastname: Ruiz-Fernández
authors.affiliation: Unidad Académica de Yucatán, Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas - Sede Mérida, Universidad Nacional Autónoma de México, Av. Colón 503F, 97000 Mérida, Yucatán, Mexico.
authors.forename: Erik
authors.initials: E
authors.lastname: Molino-Minero-Re
authors.affiliation: Oceans Catalonia International SL, Anselm Clavé, 8, 17300 Blanes, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Cruzado
mesh_terms: D000818:Animals; D017756:Aquaculture; D004784:Environmental Monitoring; D008800:Mexico; D033561:Penaeidae / Q000502:physiology*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000517:prevention & control*; D060753:Water Quality
chemical_list: D014874:Water Pollutants, Chemical
keywords: Aquaculture; Biogeochemical model; Coastal zone management; Gulf of California; Shrimp farm; Tidal cycle