Relationships between copepod community structure, rainfall regimes, and hydrological variables in a tropical mangrove estuary (Amazon coast, Brazil)

Abstract

The influence of rainfall and hydrological variables on the abundance and diversity of the copepod community was investigated on a monthly basis over an annual cycle in the Taperaçu mangrove estuary. In general, the results show that there were no clear spatial or tidal patterns in any biological variables during the study period, which was related to the reduced horizontal gradient in abiotic parameters, determined mainly by the morphological and morphodynamic features of the estuary. Nevertheless, seasonal and monthly trends were recorded in both the hydrological data and the abundance of the dominant copepod species. In particular, Pseudodiaptomus marshi (6,004.6 ± 22,231.6 ind m -3 ; F = 5.0, p \ 0.05) and Acartia tonsa (905.6 ± 2,400.9 ind m -3 ; F = 14.6, p \ 0.001) predominated during the rainy season, whereas Acartia lilljeborgii (750.8 ± 808.3 ind m -3 ; U = 413.0, p \ 0.01) was the most abundant species in the dry season. A distinct process of succession was observed in the relative abundance of these species, driven by the shift in the rainfall regime, which affected hydrological, in particular salinity, and consequently the abundance of copepod species. We suggest that this may be a general pattern governing the dynamics of copepod populations in the estuaries of the Brazilian Amazonian region.

Copepod assemblages in a highly dynamic equatorial estuary on the Brazilian Amazon Coast

“…In contrast with middle latitudes, where temperatures oscillate considerately, the seasonal cycle of equatorial coasts is characterized by major fluctuations in rainfall levels and fluvial discharge, with salinity being the principal factor determining the composition of copepod communities. As in other Amazonian estuaries, salinity levels fluctuated considerably in the Caet e Estuary during the study period (Barletta-Bergan et al 2002; Pamplona et al 2013; Magalhães et al 2015). In addition to rainfall and freshwater discharge, tides and strong winds (see Kennish 1994) may also have contributed to the observed variation in conditions.…”

“…; Magalhães et al . ). In addition to rainfall and freshwater discharge, tides and strong winds (see Kennish ) may also have contributed to the observed variation in conditions.…”

“…, ; Magalhães et al . ). While differing in some respects from the main Amazon estuary, these estuaries are equally dynamic and productive environments.…”

“…Few data are available on the zooplankton of Amazonian estuaries, and most studies, as this one is, have focused on sites located outside the plume of the Amazon River (Krumme & Liang 2004;Costa et al 2008Costa et al , 2009Leite et al 2009Leite et al , 2010Magalhães et al 2015). While differing in some respects from the main Amazon estuary, these estuaries are equally dynamic and productive environments.…”

Influence of a Drought Event on Hydrological Characteristics of a Small Estuary on the Amazon Mangrove Coast

“…In addition, nutrient and chlorophyll-a concentrations are strongly influenced by anomalous climatic events in different latitudes. Wilkerson et al (2002) During the rainy season, the increased fluvial discharge dominates most Amazon estuaries (Costa et al 2013b;Pamplona et al 2013;Pereira et al 2010), reducing the salinity of the region's coastal waters, including those of the Taperaçu Estuary (Costa et al 2013a;Magalhães et al 2015;Souza-Junior et al 2013). Thus, the effect of the drought event seems to be greater during the rainy season, possibly because 80-90% of the total annual precipitation occurs during this period.…”