Tracking of spatial changes in the structure of the zooplankton community according to multiple abiotic factors along a hypersaline lagoon

Abstract

In this study we evaluated the effects of changes in salinity, temperature, pH and dissolved oxygen on the spatiotemporal variation of zooplankton. Samples were collected in January−March, May; October−December 2010; and January−March 2011 in the Araruama lagoon, state of Rio de Janeiro, Brazil. There were eight fixed stations sampled using a WP2 net equipped with a flow meter. The zooplankton diversity of the Araruama lagoon was low and dominated by Cirripedia larvae and by the copepod Acartia tonsa, which is an indicator species of eutrophication. In general, a few species from the Cabo Frio region were able to adapt to the conditions of this hypersaline lagoon. In addition, a specimen of Monstrilla bahiana (Monstrilloidae) was found at a salinity of 46‰. This is the first record of the order Monstrilloida in the region of Cabo Frio. Temperature, salinity and pH were shown to be limiting factors for the species present in the lagoon since Cirripedia seemed to avoid releasing their larvae under unfavorable environmental conditions. The abundance of A. tonsa was always associated with that of Cirripedia larvae, and it was higher at cooler temperatures.

Copepod Assemblages at the Base of Mangrove Food Webs during a Severe Drought

“…A particular feature of this tropical drought-prone estuary is the low number of species (n = 20) when compared to other estuaries in Brazil ( [52] (n = 49); [53] (n = 30); [54] (n = 37)) and elsewhere in the world ( [55] (n > 100); [56] (n = 47), [57] (n = 32)). Increased salinity can modify the structure and dynamics of planktonic communities through the selection of predominantly stress-tolerant marine species [58] and consequent simplification of planktonic communities, as observed in hypersaline estuaries, which have low numbers of species with high densities [14,59]. The lack of regular flow-through dams observed on this tropical coast induce an increase in hypersalinity in the mangrove estuarine ecosystem already affected by the drought effects [29] and may cause direct repercussions on species composition.…”

Seasonal Changes in the Size Distribution of Copepods Is Affected by Coastal Upwelling

“…Due to the large number of species, zooplankton occupies distinct ecological niches and plays key roles in ecosystem functioning [7], such as transferring energy to the higher trophic levels [3,7,17]. In addition, the zooplankton community is sensitive to environmental changes that have been reported in recent decades [18][19][20][21].…”

“…In the marine environment, copepods are the most abundant and diverse zooplankton group [20,22], and since several species of fish consume them, they are also responsible for most of the secondary production in the oceans [3,23]. Despite copepods being highly diverse and abundant, the size of copepods is one of the most valuable parameters revealing the ecological and physiological constraints of marine planktonic populations [9].…”

“…Despite copepods being highly diverse and abundant, the size of copepods is one of the most valuable parameters revealing the ecological and physiological constraints of marine planktonic populations [9]. Many environmental conditions, like water temperature, can control physiological processes that influence the size distribution of organisms in a population, therefore changing the food availability in the marine ecosystem [9,20,24].…”