Composition, Body-Size Structure and Biomass of Zooplankton in a High-Elevation Temporary Pond (Minas Gerais, Brazil)

Abstract

Small ponds are vital inland water bodies, recognized as small repositories of freshwater biodiversity, but neglected in terms of conservation. Although high-elevation ponds are difficult to sample and monitor, it is important to extend their study, in view of their importance to aquatic biodiversity. The aim of this study was to analyze the composition, size structure biomass and diversity of zooplankton community in a temporary pond (Lagoa Seca) of a low-alpine area in the southern part of Serra do Espinhaço mountain in Minas Gerais State, Brazil. Three ecological aspects were analyzed: (I) the taxonomic composition of the zooplankton assemblage, (II) the size structure and biomass of the main groups in the zooplankton community and (III) whether the morphometric characteristics and biomass of the zooplankton result from the dominance of the microzooplankton, as expected in habitats subjected to frequent and strong disturbances, such as temporary ponds. Zooplankton samples were taken during the rainy period (October 2010 to January 2011) in different mesohabitats, from the shallowest areas covered by emergent macrophytes to the open water area covered mainly by submerged macrophytes. The zooplankton community consisted of a small number of taxa (29). Rotifera showed the highest richness, with 21 taxa recorded, of which the most constant species were the cosmopolitan Lecane lunaris, L. obtusa and Lepadella patella. Among the Cladocera, Bosmina freyi and Moina minuta were the pelagic species recorded. The other cladoceran species observed are associated with littoral vegetation, and represented mainly by Alona ossiani, Chydorus pubescens, Ephemeroporus tridentatus and Ilyocryptus spinifer. The zooplankton biomass was very low (the maximum dry weight, observed at the peak of the rainy period in January was 62 µg.m-3). The zooplankton community was dominated by the microzooplankton, with the maximum body length below 900 µm. This assemblage was very changeable in the short term, both in numerical density and size structure, probably because of the highly variable hydrological regime of the pond. The results from zooplankton composition, including the first record of the rotifer Microcodon clavus to Minas Gerais state and the second in Brazil, highlighted the important role that high-elevation temporary ponds can play as aquatic biodiversity reserves. These unique ecosystems deserve greater efforts of research and monitoring, including studies of their hydrological patterns, biological diversity, and adaptive mechanisms of the zooplankton community.

Zooplankton community structure from tropical temporary ponds during a flood period

“…Other studies in Brazilian aquatic ecosystems recorded much higher zooplankton species richness both in temporary and in perennial environments (reservoirs and rivers). Passos (2012) found 20 to 23 taxa in three shallow temporary ponds in the municipality of Urucuia, Minas Gerais (near to the ponds of this study); Passos (2017) registered 68 taxa for a total of 25 shallow temporary ponds from Minas Gerais (municipalities of Urucuia, Lagoa Grande and Pirapora) studied during three consecutives years (2015 to 2017); Moreira et al (2016) registered 29 taxa in a shallow high-elevation temporary pond in Minas Gerais; in São Paulo State, Melão (1997) found 28 taxa in a shallow permanent oligotrophic reservoir and Santos (2010) found richness ranging from 17 to 36 in three large big reservoirs of Tietê River (São Paulo); Silva (2015), in a review of studies done in large amazonic rivers, reported 143 species in the Madeira River and 129 species in the Xingu River. It is possible, however, that our results underestimate the real richness of zooplankton species in the studied ponds, since we did a single sampling campaign and resistance eggs of the species from such temporary ecosystems can hatch in different times (Passos, 2017).…”

Egg production and life history of Alona guttata Sars, 1862 (Cladocera, Chydoridae): implications for colonization of temporary ponds

“…Each female produced a mean of 10 ± 3.46 broods during its life cycle. After egg production halted, females survived for 2.5 ± 0.98 days, usually abundant in shallow lakes (Moreira et al, 2016). Their abundance can be associated with the close relationship with the dense presence of aquatic vegetation (Bolduc et al, 2016), since they are specialized in exploiting microenvironments provided by vegetation (Scheffer, 2004;Forró et al, 2008).…”

“…The pond is an oligotrophic, slightly acid seasonal aquatic water body, with mean value of pH below 6.5 and mean annual water temperature of 19 °C. (Moreira et al, 2016). Samples were obtained in January 2014 by filtration of 30 L of water in a 68 µm mesh size plankton net.…”

The relative importance of regional and local factors in shaping zooplankton diversity in high-altitude tropical shallow lakes

“…The lakes were classified in two categories according to water fluctuation: permanent or temporary (lake that dry at least once a year). To determine these categories (permanent or temporary), data from previous studies of the lakes (Moreira et al 2015;Moreira et al 2016) and information provided by the management of the Conservation Units were used. The values (lake area, altitude, macrophyte cover) and categories (permanent and temporary) were applied in the multivariate analyses (PERMANOVA) as an independent variable to explain the variations in the richness of zooplankton species.…”