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Aquatic Biology

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AB 10:273-282 (2010)  -  DOI:

Interactive effects of omnivorous fish and nutrient loading on net productivity regulation of phytoplankton and periphyton

Rafael Dettogni Guariento1,*, Luciana Silva Carneiro1,4, Adriano Caliman1,4, Reinaldo Luiz Bozelli1, João José Fonseca Leal1,2, Francisco de Assis Esteves1,3

1Universidade Federal do Rio de Janeiro (UFRJ), Laboratório de Limnologia, Av. Brigadeiro Trompowski s/n, CCS, Ilha do Fundão, Rio de Janeiro, CX Postal: 68020; 21941-590, Brazil
2Centro Federal de Educação Tecnológica (CEFET) de Química De Nilópolis/RJ, Rua Lucio Tavares, 1045, Centro–Nilópolis,
26530-060, Brazil
3Núcleo em Ecologia e Desenvolvimento Sócio-Ambiental de Macaé (NUPEM/UFRJ), São Jose do Barreto, Macaé, CX Postal: 119331 (Agência Correio de Macaé), Brazil
4Present address: Universidade Federal do Rio Grande do Norte, Centro de Biociências, Departamento de Botânica, Ecologia e Zoologia, 59072-970, Natal, RN, Brazil

ABSTRACT: Top predators and nutrient loading are key components in the regulation of community structure and biomass in aquatic ecosystems. However, few studies have addressed how these 2 components interact to determine metabolic variables of the community, such as oxygen production and respiration rates. The pelagic zone has been the focus of most research on trophic cascades. Nevertheless, recent data increasingly show the importance of periphyton to the functioning of lakes. We conducted a fully factorial field experiment in enclosures within a humic coastal lagoon to analyze the interacting effects of nutrient addition (N and P) and the presence/absence of omnivorous fish on phytoplankton and periphyton net primary productivity. Fish presence positively affected net planktonic productivity, especially when nutrients were added. However, fish presence negatively affected net periphytic productivity, probably due to 2 non-exclusive mechanisms: the increase in competition with phytoplankton, which was released from zooplankton grazing, and the direct periphytic biomass consumption by fish. We conclude that fish can alter fundamental ecosystem processes in lakes, such as internal carbon dynamics, by increasing the relative importance of pelagic to periphyton productivity.

KEY WORDS: Trophic cascade · Aquatic metabolism · Cross-habitat linkage · Food web · Shallow lake

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Cite this article as: Guariento RD, Carneiro LS, Caliman A, Bozelli RL, Fonseca Leal JJ, de Assis Esteves F (2010) Interactive effects of omnivorous fish and nutrient loading on net productivity regulation of phytoplankton and periphyton. Aquat Biol 10:273-282.

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