Nutrients and water-forest interactions in an Amazon floodplain lake: an ecological approach

Abstract

Aim: Catalão Lake was surveyed between 2002 and 2011 with the aim of studying seasonality of the flow of nutrients between water, sediment and aquatic macrophytes. The role of the flood pulse and the ecological mechanisms influencing the forest-water interactions in the Amazon floodplain were discussed; Methods: Catalão Lake is located in the Amazon floodplain (03° 08'-03º 14' S and 59° 53'-59° 58' W), near the confluence of the Solimões and Negro rivers, approximately 3000 m from the port of CEASA, near the city of Manaus. It is considered to be a mixed water lake because it receives white waters rich in sediments from the Solimões River and black waters with humic substances from the Negro River. Physical and chemical parameters including C, N and P levels were studied in the diverse compartments, and a flux model was developed; Results: There is a strong nutritional (C, N and P) and ionic (Na + ) flow from the rivers to the lake. The highest C:N:P ratio was found in Paspalum repens which, during periods of drought, played an important role in releaseing nutrients into the water. The connectivity of the lake with the rivers ensured a high variation of transparency and nutrient content, fundamental for biological processes. A model of the nutrient flow, interaction and connectivity between ecosystems, and the influence of the hydrological cycle has been developed.,Keywords: carbon, nitrogen, phosphorus, connectivity, Amazonian mixed lake.Resumo: Objetivo: O lago Catalão foi pesquisado entre 2002 e 2011 com o objetivo de estudar sazonalmente o fluxo de nutrientes entre os compartimentos água, sedimento e macrófitas aquáticas. O papel do pulso de inundação e os mecanismos ecológicos que influenciam a interação aquático-florestal na planície amazônica foram discutidos; Métodos: O lago Catalão está localizado na planície amazônica, próximo à confluência dos rios Solimões e Negro, aproximadamente 3000 m do porto da CEASA, próximo a cidade de Manaus. Ele é considerado um lago misto, que recebe águas brancas ricas em sedimentos do rio Solimões e águas pretas contendo substâncias húmicas do rio Negro. Parâmetros físicos e químicos incluindo teores de C, N e P foram estudados nos diversos compartimentos, e um modelo de fluxo foi desenvolvido; Resultados: Há um forte fluxo nutricional (C, N e P) e iônico (Na, Cl -, HCO 3-, CO 3 2-e SO 4 2-) dos rios para o lago. Dentre as espécies de plantas mais abundantes a maior razão C:N:P foi encontrada na Paspalum repens, que durante os períodos de seca teve importante papel na liberação de nutrientes para a água, garantindo a manutenção da vida das espécies aquáticas. A conectividade do lago com os rios garantiu uma alta variação da transparência e teores de nutrientes, fundamentais nos processos biológicos. Um modelo de fluxo de nutrientes, interação e conectividade entre os ecossistemas, e a influência do ciclo hidrológico, foram desenvolvidos.Palavras-chave: carbono, nitrogênio, fósforo, conectividade, lago misto da Amazônia., 2013, vol. 25, no. 2, p. 169-182 http:/...

Diel patterns of temperature, conductivity and dissolved oxygen in an Amazon floodplain lake: description of a friagem phenomenon

“…With the exception of the friagem event in May, all of the diel temperature patterns observed in 2007 indicated a regime of permanent stratification, similar to that described by Aprile and Darwich (2013) during the high water period. The general pattern described by MacIntyre (1993) included: 1) windless conditions and high incident radiation resulting in the warming surface waters in the morning, 2) increased winds and continued warming in the afternoon and 3) surface cooling combined with moderate winds at night resulting in the vertical mixing of surface waters to a depth defining the daily mixed layer (Imberger, 1985), The depth of the daily mixed layer varied from 5m at late rising water to 2m at falling water.…”

“…Like alkalinity (Forsberg et al, 1988), conductivity proved to be a good indicator of the water balance in Lago Catalão, accurately reflecting the relative mixture of waters from the Rio Negro and Rio Solimões present in the lake throughout most of the year (Aprile and Darwich, 2013). The low water results (November 2006) were exceptional in this sense with conductivity values exceeding the maximum levels encountered in either river.…”

Seasonal dynamics of the fish assemblage in a floodplain lake at the confluence of the Negro and Amazon Rivers

“…Although the lake receives a large input of water from both rivers, the Negro appears to have greatest influence on water quality during the early rising‐water period, resulting in lower values of conductivity and pH, and the Amazon has dominant influence during most other periods (Brito et al ., ; Caraballo et al ., ). The seasonality of connectivity with both rivers and isolation during the dry season and correlated changes in water level also influence dissolved inorganic nutrient concentrations (Aprile & Darwich, ) and local phytoplankton productivity (Almeida & Melo, ).…”

Growth–reproduction trade‐off and fecundity regulate population stability in Amazon floodplain fishes

“…Amazon floodplain lakes are not permanently disconnected from the main channel; the seasonal water level variation largely determines their connectivity with the main channel and nearby environments, which determines movement of individuals across environments (Fernandes, 1997). The seasonality of connectivity and isolation also influence water quality due to influx of dissolved organic and inorganic nutrients and local phytoplankton productivity (Almeida & Melo, 2011; Aprile & Darwich, 2013; Freitas et al., 2013; Röpke et al., 2016).…”