Estratégias funcionais da comunidade de macrófitas de um trecho do baixo curso do rio Jari, sul do Amapá, Brasil

Abstract

The Jari River is characterized by an extensive floodplain with high seasonal hydrological dynamics that suffers from human intervention due to urban expansion and the dumping of sewage directly into the river. These factors can influence the distribution of aquatic macrophytes, plants that have a great capacity for adaptation and ecological breadth. However, there are no studies that consider the distribution of macrophyte species considering the variation in functional attributes (ecological strategies) along the Jari River. In this sense, the present study aims to analyze the functional strategies of the aquatic macrophyte community in a stretch of the lower course of the Jari river, in the south of Amapá, based on the hypothesis that aquatic macrophytes can exhibit the trade-offs of resource acquisition and conservation. to coexist in different physical-chemical conditions of water. Three 1m2 plots were established at four points along a stretch of the river, totaling 12 plots. The species were identified, five leaves were collected from individuals in the plots to measure four functional attributes. The physical- chemical parameters of the water in each plot were also analyzed. The emerging way of life was predominant among the species. Eichhornia azurea (Sw.) Kunth was common to the four collection points; Salvinia auriculata Aubl., Azolla sp. and Cyperus blepharoleptos Steud. stood out for their greater abundance. There was a trade-off between leaf size/thickness and amount of leaf mass in the macrophyte community analyzed. Three distinct strategies were found upstream of the river: macrophytes with large, thick leaves in water with greater conductivity, such as E. azurea and P. repens, occurred in front of the city due to the ability of these plants to multiply in polluted environments; macrophytes with greater mass display area in water with greater turbidity and temperature; and macrophytes that have a greater amount of dry mass in the leaves, a strategy of resistance or resource conservation. It is recommended that long-term studies be carried out to monitor the ecological strategies of macrophytes under the influence of precipitation seasonality and climate change, providing a robust database for making decisions for the management and conservation of aquatic ecosystems.