Charophytes as a nutrient and energy reservoir in a tropical coastal lagoon impacted by humans (RJ, Brazil)

Abstract

In the Imboassica Lagoon (22 degrees 24'S and 42 degrees 42'W) (Macaé, RJ, Brazil), two species of macroalgae of the genus Chara (C. angolensis and C. fibrosa) registered in large areas were identified. The lagoon is subject to several relevant anthropic impacts, of which untreated sewage is one of the most important. Results of the biomass distribution as analyzed in different areas of the lagoon showed values ranging from 172 to 510 gDW x m(-2). As for the nutrient concentration, the results presented large fluctuations, with carbon values ranging from 325 to 392 mg x g(-1)DW, those of nitrogen, from 14 to 27 mg x g DW, and of phosphorus from 0.45 to 0.85 mg.g(-1) DW. This led to large fluctuations of the C:N:P ratio (from 387:24:1 to 872:47:1). The minimum and maximum energetic values of the biomass were 9.54 e 12.34 kJ x g(-1)DW. Smaller C:N:P ratios tended to occur in more eutrophic areas. The association between biomass and nutrient concentration showed that the highest quantities in the beds are found in oligotrophic areas. The Spearman correlation between nutrient concentration in the water column and biomass was r(s) = 0.45 (p < 0.05) for nitrogen and r(s) = 0.50 (p < 0.01) for phosphorus (n = 30). The large total biomass associated with nutrient concentration and energy content indicates that Charophytes are an important biological compartment in the structure and metabolism of the lagoon.

Biomass and chemical composition of Nitella furcata subsp. mucronata var. mucronata f. oligospira (A. Braun) R. D. Wood (Chlorophyta, Characeae) in the littoral region of Ninféias Pond, São Paulo, Southeast Brazil

“…Similar behavior was verified by Da-Silva & Esteves (1993) in the Barão de Melgaço Pantanal, state of Mato Grosso. Palma-Silva et al (2004) detected positive correlation between N and P concentrations in the charophyte and the water column, a condition that was also detected by Garten (1976) for charophytes and some other non-vascular plants.…”

“…Study on Characeae of lotic environments in Brazil is restricted to those of Vieira and ; and on material from lentic systems to those of Palma-Silva et al (2002a, 2002b, 2004 and Bueno & Bicudo (2006). are taxonomic papers and dealt, respectively, with the floristic survey of genera Nitella and Chara in lotic systems of the southeastern region of the state of São Paulo.…”

“…Palma-Silva et al (2002b) studied the role of charophyte primary production in the above same lagoon subjected to human impact. Palma-Silva et al (2004) approached the charophytes as a nutrient and energy reservoir in the same lagoon above, under anthropic impact. Finally, Bueno & Bicudo (2006) …”

Temporal variation in the biomass and nutrient status of Azolla filiculoides Lam. (Salviniaceae) in a small shallow dystrophic lake

“…For example, a constant input of phosphorus from the discharge of sewage frequently produced low N:P ratios (e.g., N:P ratios in Chara spp. Ranging from 19:1 to 47:1) (Palma-Silva et al, 2004). In view of the N:P reference ratios presented in Atkinson and Smith (1983), we suggest that A. filiculoides showed no deficiency of either N or P.…”

O papel das Macrófitas aquáticas emersas no ciclo do fósforo em lagos rasos

“…Além disso, este grupo de plantas pode liberar fósforo para a coluna d'água até através de folhas saudáveis (graneli & Solander 1988). Vários trabalhos apresentam grupos de macrófitas submersas como sumidouros de fósforo (Kufel & Kufel 2002, Palma-silva et al 2004, mas este conceito deve ser aplicado com ressalvas. A falta de consideração de uma escala temporal relativamente longa faz com que o conceito de sumidouro seja utilizado de forma equivocada, já que o armazenamento de fósforo em biomassa vegetal em curta escala de tempo, associado a baixa longevidade destes vegetais em ecossistemas aquáticos pode ser considerada apenas como um sequestro temporário de fósforo.…”