Benthic algal community structures in a bivalent eutrophied tidal channel system at the Northern Patagonian Atlantic coast

FRICKE, A.; NARVARTE, M.; KOPPRIO, G.; MARTINEZ, A.; ALEMANY, D.; GASTALDI, M.; IRIBARNE, O.; LARA, R.J.; PARODI, E.R.

Rostock

Conferencia; 15th Scientific Conference of the Sektion Phykologie of the Deutsche Botanische Gesellschaft. Rostock, Alemania. 23-27 feb.; 2014

Deutsche Botanische Gesellschaft.

Eutrophication is one of the most severe anthropogenic impacts of coastal habitats. Benthic algae react sensitively to changes in ambient nutrient concentrations, which can be observed in algal blooms and an alteration in whole community structure. A change in the algal communities can affect the benthic ecosystem and might alter the top-down bottom-up balance. Due to its extended size and the presence of pristine sites close to human impacted areas, the Argentinean Patagonian coast provides a unique possibility to study and directly compare the potential effect of anthropogenic activities on the benthic ecosystem. Nevertheless, knowledge of Patagonian benthic algal communities is currently scarce, compared to that of northern latitudes. Aim of the present work is to investigate benthic algal communities at the North Patagonian Atlantic coast, in terms of 1) algal succession, 2) species composition, 3) community structure and 4) chemical algal community composition, in relation to different environmental conditions. Three manipulative multifactorial field experiments were conducted during spring and autumn 2012/13 at the study site at San Antonio Bay (S40 43 W64 56). In October 2012 a total of 42 experimental units were exposed in the subtidal of the SAO channel for a period of three weeks, testing the interactive effect of nutrient enrichment (3 levels) on early and late successional communities. In March 2013 a total of 30 experimental units were exposed in parallel at a pristine and a polluted site for a period of two weeks, to test the interactive effect of nutrient enrichment (3 levels) on naturally grown and site-cross transplanted communities. In parallel the natural succession was followed at a pristine and a polluted site over a period of 357 days. Results of the present study give a first and deep insight into the diversity and complexity of benthic algal communities of the area. Findings of this study provide valuable information which can be used as a baseline for further studies investigating potential anthropogenic impact and as ecological indicators to improve coastal zone management.