Coastal upwelling may overwhelm the effect of sewage discharges in rocky intertidal communities of the Peruvian coast
Fausto N. Firstater A B E , Fernando J. Hidalgo A B , Betina J. Lomovasky A B , Juan Tarazona C , Georgina Flores D and Oscar O. Iribarne A BA Laboratorio de Ecología, Departamento de Biología, FCEyN, Universidad Nacional de Mar del Plata, CC 573 Correo Central, B7600WAG, Mar del Plata, Argentina.
B Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.
C Departamento de Biología, Universidad Nacional Mayor de San Marcos, Apartado 1898, Lima 100, Perú.
D Dirección de Investigaciones Oceanográficas – Unidad de Investigaciones en Oceanografía Química, Instituto del Mar del Perú, PO Box 22, Callao, Perú.
E Corresponding author. Email: firstate@mdp.edu.ar
Marine and Freshwater Research 61(3) 309-319 https://doi.org/10.1071/MF09102
Submitted: 7 May 2009 Accepted: 21 August 2009 Published: 29 March 2010
Abstract
In coastal productive environments, such as upwelling systems, sewage effluents might represent an important input of nutrients affecting intertidal community development and structure. Using descriptive and experimental approaches, the community spatial variation and early succession in relation to a point-source effluent discharge in a rocky intertidal of an upwelling affected area (Ancón Bay, Peru) was analysed. The relative contribution of herbivory to the observed patterns was also analysed. Dissolved nutrient concentrations, macroalgal isotopic signatures and N content revealed a significant input of nutrients at the outfall, although this contribution was not reflected in the algal assemblage, but in higher abundances of mytilids, ophiuroids and limpets. Cover of most sessile organisms (biofilm, Ulva spp., mytilids and barnacles) varied among sites throughout early succession, and grazers only enhanced the cover of the red algae Gelidium spp. Differences in succession patterns could not be attributed to discharge effects. The results of this study suggest that the community development is bottom-up controlled in the entire bay, which is likely to be due to the upwelling that operates at larger temporal and spatial scales. If so, nutrient input derived from coastal upwelling may sometimes overwhelm the role of anthropogenic nutrient loadings in shaping intertidal communities.
Additional keywords: bottom-up, community structure, Peru, succession.
Acknowledgements
We thank Elmer Ramos for helping with logistics and laboratory resources, Percy Gallegos and Carlos Paredes for collaborating in species identification, Patricia Gamero and Michelle Graco for sampling and remarks. Comments by Drs Ivan Valiela and Hsing-Juh Lin were helpful in data interpretation. We also thank two anonymous reviewers for their comments that greatly improved this manuscript. This study was conducted and financed in the framework of the EU-project CENSOR (Climate variability and El Niño Southern Oscillation: Implications for natural resources and management, contract 511071) and is CENSOR publication No. 0353.
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