Fishes as indicators of untreated sewage contamination in a Mexican coastal lagoon.
Lagoons are important nursery habitats for fishes but are often sites of intense human activity including wastewater discharges. The goal of this research was to compare stable nitrogen (δ15N) and carbon (δ13C) isotopes, total mercury (THg) and other metal levels in four selected fish species among sites with different levels of untreated sewage discharge inside Barra de Navidad coastal lagoon in the Mexican Pacific. Three species from sites heavily impacted by sewage showed higher δ15N and δ13C compared to those from non-impacted sites. In addition, the highest concentrations of THg were present in fish of two species (Sciades guatemalensis and Diapterus brevirostris) collected at the two most impacted sites, and exceeded the 0.2μg/g ww threshold believed to be protective of adult and juvenile fish. No individuals of Achirus mazatlanus and Mugil curema exceeded this threshold, and liver somatic index and condition did not distinguish high from low impacted sites for all species. In general, the metal levels differed among species but not sites, and were lower than what has been measured in fishes elsewhere. The study also provides the first information on several fish species for coastal areas of Mexico, suggests that THg and isotopes can distinguish sewage-impacted sites, and can serve as a baseline for future studies.
Department of Studies for Sustainable Development of the Coastal Zone, University of Guadalajara, Jalisco, Mexico; Canadian Rivers Institute and Biology Department, University of New Brunswick, Saint John, New Brunswick E2L 4L5, Canada.
Consuelo M
CM
Aguilar-Betancourt
Department of Studies for Sustainable Development of the Coastal Zone, University of Guadalajara, Jalisco, Mexico; Canadian Rivers Institute and Biology Department, University of New Brunswick, Saint John, New Brunswick E2L 4L5, Canada.
Gaspar
G
González-Sansón
Canadian Rivers Institute and Biology Department, University of New Brunswick, Saint John, New Brunswick E2L 4L5, Canada. Electronic address: kiddk@unb.ca.
Karen A
KA
Kidd
Canadian Rivers Institute and Biology Department, University of New Brunswick, Saint John, New Brunswick E2L 4L5, Canada.
Kelly R
KR
Munkittrick
Canadian Rivers Institute, Biology, Forestry and Environmental Management, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada.
R Allen
RA
Curry
Department of Studies for Sustainable Development of the Coastal Zone, University of Guadalajara, Jalisco, Mexico.
Daniel
D
Kosonoy-Aceves
Department of Studies for Sustainable Development of the Coastal Zone, University of Guadalajara, Jalisco, Mexico.
Gabriela
G
Lucano-Ramírez
Department of Studies for Sustainable Development of the Coastal Zone, University of Guadalajara, Jalisco, Mexico.
Salvador
S
Ruiz-Ramírez
Escuela Nacional de Ingeniería Pesquera, Universidad Autónoma de Nayarit, Nayarit, Mexico.
Juan R
JR
Flores-Ortega
D000818:Animals; D002247:Carbon Isotopes / Q000032:analysis; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods*; D005399:Fishes / Q000254:growth & development / Q000378:metabolism*; D006801:Humans; D008628:Mercury / Q000032:analysis* / Q000378:metabolism; D008800:Mexico; D009587:Nitrogen Isotopes / Q000032:analysis; D012722:Sewage / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism
D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D012722:Sewage; D014874:Water Pollutants, Chemical; D008628:Mercury
Bioindicator; Coastal lagoon; Fishes; Isotopes; Mercury; Metals; Sewage