Navegando por Assunto "Salinity"

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Acesso aberto (Open Access)
O efeito da salinidade no desenvolvimento larval do caranguejo-uçá, Ucides cordatus (Linnaeus, 1763) (Decapoda: Ocypodidae) no Norte do Brasil
(Instituto Nacional de Pesquisas da Amazônia, 2008) SIMITH, Darlan de Jesus de Brito; DIELE, Karen
The present work studied the effect of salinity on the survival and duration of larval development of the mangrove crab, Ucides cordatus (from the Caeté River estuary, North of Brazil) until the megalopal phase in seven salinity treatments (0, 5, 10, 15, 20, 25 e 30). Salinity significantly affected the survival of the zoea larvae, however it did not affect the duration of the larval development (20.77 ± 1.56 days). In salinity 0, 5 and 10 all zoea larvae died. Only from off salinity 15, complete development until the megalopal phase occurred. The survival rate was highest in salinity 30 (72%) and lowest in 15 (16%). The reduced survival rate of the U. cordatus zoea larvae, in low salinities, indicates the necessity of larval dispersion from the estuary to coastal waters, where salinity conditions for larval development are more favorable. Otherwise, if there was no dispersion, the reduced salinity of estuarine waters in the rainy season would cause a high mortality thereby affecting the recruitment, maintenance and growth of the U. cordatus population in the mangroves.
Acesso aberto (Open Access)
Seasonal variation in the copepod community structure from a tropical Amazon estuary, Northern Brazil
(Academia Brasileira de Ciências, 2009-06) MAGALHÃES, André Luiz Perez; LEITE, Natália da Rocha; SILVA, João Gabriel Souza; PEREIRA, Luci Cajueiro Carneiro; COSTA, Rauquírio André Albuquerque Marinho da
The main purpose of this study was to investigate the seasonal variation of copepod community structure during the months of July, September and November 2003 (dry season) and January, March and May 2004 (rainy season) in the Curuçá estuary, northern Brazil. Samples were collected during neap tides via gentle 200µm mesh net tows from a small powerboat. Measurements of surface water conductivity were accomplished in situ using an electronic conductivimeter and salinity was later obtained through the transformation of the conductivity values. Salinity varied seasonally from 7.2 ± 0.1 to 39.2 ± 1.8 (mean ± standard deviation) and was influenced mainly by differences in the amount of rainfall between the studied sampling seasons. In total, 30 Copepoda taxa were identified and Acartia tonsa comprised the most representative species throughout the entire studied period followed by Acartia lilljeborgii, Subeucalanus pileatus and Paracalanus quasimodo. In the present study, the density values, ecological indexes and copepod species dominance presented a clear seasonal pattern, showing that the studied area may be considered seasonally heterogeneous in relation to the investigated parameters.
Acesso aberto (Open Access)
Variação interanual e sazonal das massas d’água sobre a Plataforma Continental Norte do Brasil
(Universidade Federal do Pará, 2021-12-20) MEDEIROS, Paula Renata Lobato de; ROSÁRIO, Renan Peixoto; http://lattes.cnpq.br/8003860457518342; https://orcid.org/0000-0003-2913-0514
This study aimed to analyze the spatial and temporal variability of water masses over the Northern Continental Shelf of Brazil (PCNB), relating it to local dynamics and freshwater inputs. The PCNB extends from Cape Orange to the Bay of São Marcos and is characterized as highly energetic, due to the combined action of the north current of Brazil (CNB), trade winds, waves, tides and the water discharge from the Amazon rivers and Pará. Temperature, salinity and density data for the interannual analysis were obtained from the Brazilian Navy's national database (BNDO), during six oceanographic cruises: Amasseds I, II and III, North Ocean I, MCT VII and CBO in different years: 1989, 1990, 2001, 2016 and for the seasonal analysis, five months of the Costa Norte Project were used: March, July, November, December 2018 and January 2019. The TS parameters were intended to characterize and identify the water masses that occurred on the platform over the years, as well as observe the existing interannual and seasonal variability. The PCNB showed large variations in TS over the years and periods analyzed, and it is possible to observe the occurrence of four types of water bodies interannually: Pluma Estuarina (PE), Coastal Water (AC), Central Water of the South Atlantic (ACAS) and Tropical Water (AT) and seasonally, five water bodies were identified as occurring: AF (front water), AC, AT, ACAS and Pluma etuarina (PE). From the analysis of the TS diagrams it was possible to identify a thermohaline index for the estuarine plume and its metrics over time, where it occurred in March - 2018 and January - 2019, and their respective thermohaline indices were 27.5 °C to 28 °C and 0 g/kg to 33 g/kg.