Diversity of chironomidae (diptera) in decomposing nymphoides indica (l.) kuntze in two subtropical lakes with different trophic conditions

• Autor(a) principal: Silva, Juliana Santos
• Data de Publicação: 2010
• Outros Autores: Silveira, Wagner Terra, Albertoni, Edélti Faria, Palma-Silva, Cleber
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da FURG (RI FURG)
• Texto Completo: http://repositorio.furg.br/handle/1/3089
• topic: Macrophyte; Functional trophic groups; Ecological succession; Detritus; Leaf breakdown; Macrófitas; Grupos tróficos funcionais; Sucessão ecológica; Detritos; Degradação foliar

Chironomids are the most abundant macroinvertebrates in macrophyte detritus. The goal of this study was to characterize the diversity of these animals in decomposing Nymphoides indica and their relationship with abiotic variables and mass loss in two subtropical shallow lakes of different trophic conditions (Polegar – oligotrophic, Biguás – eutrophic). Experiments were conducted using litter bags in the summers of 2007 and 2008. Mass loss rate, total N and P concentrations of the detritus, density of chironomids (100 gDW-1), which were identified at the genera level and classified into functional trophic groups, were all recorded. The mass loss of N. indica was fast, with merely 8.5% of dried mass remaining in samples from Lake Polegar after five days and 8.7% in those from Lake Biguás after 17 days. The decay coefficient of N. indica in the oligotrophic lake, where the experiment lasted 5 days, was high (k=0.4242 d-1), as were the diversity and evenness of chironomids. In the eutrophic lake, the experiment lasted 17 days; the decay coefficient was lower (k=0.1199 d-1), as weel as diversity. The genus Goeldichironomus was the most abundant of the 13 genera found in each lake. Our results demonstrate that trophic level influences the colonization of chironomids in detritus in addition to determining the structure and ecological succession of functional trophic groups.