Effects of organic pollution in the distribution of annelid communities in the Estero de Urías coastal lagoon, Mexico

Abstract

SUMMARY: The Estero de Urías coastal lagoon is subjected to several anthropogenic activities and has been characterized since 1997 through the study of benthic fauna. We analyzed the spatial and temporal distribution of annelids and their relationships with environmental variables (depth, sediment temperature, grain size and organic matter) in order to determine the current degree of perturbation. Density, species richness, diversity, dominance, biomass, and the application of classification and ordination techniques allowed us to distinguish 5 zones: 1) a non-perturbed zone at the mouth of the lagoon, 2) a slightly perturbed zone surrounded by mangroves and shrimp farms, 3) a temporarily perturbed zone close to the effluent of the thermoelectric plant, 4) a perturbed zone in front of the slaughterhouse and fish factory, and 5) a very perturbed zone subjected to sewage and industrial input. Only minor changes in granulometry and faunal composition were observed in comparison with previous data from the same area, suggesting that the lagoon is still perturbed due to the effect of anthropogenic activities.Keywords: Polychaeta, Oligochaeta, soft-bottoms, indicator species, human activities, Sinaloa. RESUMEN: Efectos de la contaminación orgánica sobre la distribución de las comunidades de anélidos en la laguna costera "Estero de Urías" (Mexico). -La laguna costera "Estero de Urías" se encuentra sujeta al efecto de varias actividades antropogénicas y ha sido caracterizada desde 1997 a través del estudio de la fauna bentónica. Con el fin de conocer el grado de perturbación actual, se analizó la distribución espacial y temporal de los anélidos, así como su relación con las variables ambientales (profundidad, tamaño de grano, materia orgánica y temperatura del sedimento). Los valores de densidad, riqueza específica, diversidad, dominancia, biomasa y la aplicación de técnicas de clasificación y ordenación permitieron distinguir cinco zonas: 1) zona no perturbada, en la boca de la laguna; 2) zona ligeramente perturbada, bordeada por manglares y granjas camaronícolas; 3) zona temporalmente perturbada, cerca del efluente de la planta termoeléctrica; 4) zona perturbada, frente al matadero y la fábrica procesadora de pescado; 5) zona muy perturbada, sujeta al efecto de los desechos domésticos e industriales. La comparación con los datos previos registrados para la misma zona indica que la laguna ha sufrido sólo cambios ligeros en la granulometría y en la composición faunística. Esto sugiere que la laguna aún se encuentra perturbada debido al efecto que producen las actividades antropogénicas.

Spatial distribution of intertidal sandy beach polychaeta along an estuarine and morphodynamic gradient in an eutrophic tropical bay

“…The effect of organic pollution in the distribution of annelid assemblages was detected in a Mexican coastal lagoon with different sources of disturbances caused by anthropogenic activities (Ferrando and Mendez, 2011). An area located close to a fish processing factory classified as a disturbed zone due to its high organic content (12.9%) was dominated by Ophryotrocha puerilis, Nereis procera, S. benedicti and Capitella sp., species well-known for their occurrence in eutrophic habitats (Ferrando and Mendez, 2011).…”

“…In a typical estuarine gradient, macrofauna density and diversity increases from inner to inlet areas (Lardicci and Rossi, 1998). This general pattern can be altered by many anthropogenic factors such as the discharge of sewage effluents, man-made alterations of the channel or coast line, fish farms and aquaculture (Ferrando and Mendez, 2011;Nalesso et al, 2005). An opposite pattern, with higher macrofauna density and species richness at the inner estuarine area was also recorded (Cardoso et al, 2012;Carvalho et al, 2005;Taurusman, 2010).…”

“…Macrofauna of shallow estuarine bays and lagoons have been focus of many studies about the effect of anthropogenic impacts on coastal areas (Carvalho et al, 2005;Ferrando and Mendez, 2011;Lardicci and Rossi, 1998). However, in estuarine areas, major shifts in the physico-chemical water parameters mask the pollution effects on macrobenthic assemblages (Rakocinski et al, 1997).…”

Spatial and temporal changes in macrobenthic communities in the Amazon coastal zone (Guajará Estuary, Brazil) caused by discharge of urban effluents

“…High densities of oligochaetes have also been reported in impacted areas with muddy and organically enriched sediment in estuaries and shallow-water marine habitats in temperate (Sardá et al 1996, Warwick 2001) and tropical regions (Ferrando andMéndez 2011, Pagliosa andBarbosa 2006) of the world. The subfamily Tubificinae, the most abundant group in this study, is traditionally considered an opportunistic taxon associated with organic enrichment and which is tolerant of low oxygen levels (Caspers 1971, Pearson and Rosenberg 1978, McLusky et al 1980.…”

Thermal Impact from a Thermoelectric Power Plant on a Tropical Coastal Lagoon

“…Ferrando and Mendez (2011) report that benthic fauna close to the thermoelectric power plant release point is perturbed in the warm season (August). However, our results indicate that the thermal impact is restricted to the surface layer (Figure 6), thus the plant cooling water release could not affect directly the benthic ecosystems.…”