Responses of marine zooplankton indicators after five years of a dam rupture in the Doce River, Southeastern Brazil.

Since November of 2015, when ore tailings from a dam rupture reached the Atlantic Ocean, researchers are trying to assess the degree of impact across the Doce River and adjacent coastal area. This study aims to use the zooplankton dynamics as a tool to evaluate the environmental impact in the coastal region, five years after the rupture, during periods of low and high river flow. Doce River flow varied from 49 to 5179 m3/s and structured the zooplankton community between periods of low and high river flow, but salinity and chlorophyll-a had stronger correlation with depth (r = 0.40 and - 0.40 respectively) than with the Doce River discharge variation along the sampling period (r < 0.2). On the other hand, inorganic particles in the water and total metal concentration (dissolved + particulate), used as tracers of the iron enriched tailing (Al, Cd, Cr, Cu, Fe, V), were correlated with fluvial discharge and showed to be the main factor driving the zooplankton community dynamics. For assessing the degree of environmental impact, we tested the ecological indexes for the zooplankton community. Margalef Richness, Pielou Evenness and Shannon-Wiener Diversity varied from 2.52, 0.40 and 1.39 (all registered during high river flow period) to 9.02, 0.85 and 3.44 (all registered during low river flow period), respectively. Along with those community indicators, we evaluated the response of representative taxonomical genera such as Paracalanus, Oikopleura and Temora, regarding the Doce River flow, and found population patterns that established a baseline for future monitoring in the region. Our results showed that the zooplankton community is more fragile when the river discharge is stronger, and this pattern is confirmed by all indicators tested.

An integrated study of the plankton community after four years of Fundão dam disaster.

Mining activities can affect the environment either by the tailings releasing or dams failures. The impact of the tailings can last decades and cause chronic effects due to their toxicity. The Fundão dam collapse, a relevant environmental disaster, occurred in November 2015 in Southeastern Brazil. Tailing rich in metals reached the Doce River and arrived in the Atlantic Ocean. Previous studies revealed the acute impact of the tailings in the marine planktonic community near the Doce River mouth. The current study aims to characterize the structure of planktonic assemblages in the impacted area after four years of the disaster. Sampling occurred in November 2018, January, April, and July 2019 at 32 stations located at the marine coastal area near the Doce River mouth. Our study detected high metal concentrations in the surface waters during January 2019, when the lowest diversity and abundance of phytoplankton, lowest zooplankton diversity, and low ichthyoplankton abundance were recorded. The zooplanktonic community was structured by environmental parameters and ichthyoplankton assemblages in November 2018, January and April 2019. Nutrients and metals, mainly iron from the tailing carried by the Doce River waters to the marine environment changed the plankton community, confirming the impact of the Fundão Dam collapse in the coastal area near the Doce River mouth. The phytoplankton community, influenced by the nutrients and to a lesser extent metals concentrations, was not decisive in the zooplankton community structure. The environmental variability was driven by the meteoceanographic conditions and the Doce River flow. There was a high correlation between the zooplanktonic community and ichthyoplanktonic assemblage and the environmental factors and metals. These relations indicate the impact of the tailings from the collapse of the Fundão Dam on these communities, even after four years of the Mariana disaster.

Marine zooplankton dynamics after a major mining dam rupture in the Doce River, southeastern Brazil: Rapid response to a changing environment.

Zooplankton were sampled five days after the tailings from the Samarco dam rupture reached the ocean in the coastal region at the mouth of the Doce River. This was one of the largest environmental disasters in Brazilian history, and the impacts on the marine biota are not yet fully understood. This study aimed to evaluate the zooplankton community short term responses to the metal enrichment after the tailings reached the coastal region in different scenarios. Our results showed an acute impact on the zooplankton community, which peaked in abundance (222,958.60 ind/m3) and decreased in diversity (H' = 1.23) near the river mouth. Two copepod species, Parvocalanus sp. and Oithona nana, composed up to 61% of the total abundance and they were correlated with concentrations of Fe, Pb, Cu and Zn in particulate fraction. These species feed opportunistically on nanophytoplankton, which dominated the autotroph community, possibly in response to the iron enrichment caused by the mud flow. A shift on zooplankton species composition was also observed. During the first three days, we found the presence of oceanic species in the 20 and 30 m isobaths during an incomplete upwelling event, which directly correlated with the presence of Calanoides carinatus. However, only three days later, following a cold front passage and consequent increase of water turbidity, those species were already absent, and the zooplankton community was significantly altered (PERMANOVA, df = 1, pseudo-F = 9.2247, p = .001). Zooplankton responded quickly to the environmental changes detected during our sampling period and proved to be key factors in costal monitoring, especially in dynamic oceanographic areas such as the Doce River coastal region.

Occurrence of Caligus asperimanus Pearse, 1951 (Copepoda: Caligidae) parasitic Lutjanus spp. (Perciformes: Lutjanidae) in the western South Atlantic.

Sea lice are widespread copepods in marine teleost around the world. In this paper the first record of Caligus asperimanus Pearse, 1951 in the Western South Atlantic is documented parasitizing Lutjanus jocu and Lutjanus vivanus caught from coastal zones of Espírito Santo and Rio de Janeiro State, respectively.

Occurrence of Caligus asperimanus Pearse, 1951 (Copepoda: Caligidae) parasitic Lutjanus spp. (Perciformes: Lutjanidae) in the western South Atlantic / Ocorrência de Caligus asperimanus Pearse, 1951 (Copepoda: Caligidae) parasitos de Lutjanus spp. (Perciformes: Lutjanidae) no Atlântico Sul ocidental

Abstract Sea lice are widespread copepods in marine teleost around the world. In this paper the first record of Caligus asperimanus Pearse, 1951 in the Western South Atlantic is documented parasitizing Lutjanus jocu and Lutjanus vivanus caught from coastal zones of Espírito Santo and Rio de Janeiro State, respectively.

Resumo Os piolhos marinhos são copépodes abrangentemente relatados em teleósteos marinhos ao redor do mundo. Neste estudo, é documentado o primeiro registro de Caligus asperimanus Pearse, 1951, no Atlântico Sul Ocidental, parasitando Lutjanus jocu e Lutjanus vivanus capturados nas zonas costeiras do Espírito Santo e Rio de Janeiro, respectivamente.

Levamisole on the biochemical and hematological responses to parasitism by monogenoids in dog snapper / Efeito do levamisol na resposta bioquímica e hematológica ao parasitismo por monogenoides em dentão

ABSTRACT: The response of biochemical and hematological parameters were analyzed in dog snapper (Lutjanus jocu) grown in net cages, as well as for the specimens kept in the laboratory during an infestation by Neobenedenia melleni, and after treatment with freshwater bath and injectable application of levamisole. Significant changes were observed in N. melleni parasitized individuals, characterized by increased glucose and lactate levels, as well as a significant fish hematocrit reduction and leukocyte increase. Treatment with freshwater baths, concomitant with injectable levamisole application, showed therapeutic efficacy in several parameters after 14 days of treatment.

RESUMO: A resposta de parâmetros bioquímicos e hematológicos foram analisadas no dentão (Lutjanus jocu) cultivados em tanque-rede, bem como os exemplares mantidos em laboratório durante a infestação por Neobenedenia melleni e após o tratamento com banho de água doce e aplicação injetável de levamisol. Foram observadas alterações significativas nos indivíduos parasitados por N. melleni, caracterizado pelo aumento dos níveis de glicose e lactato, bem como significativa redução em hematócrito e aumento em leucócito dos peixes. O tratamento com banhos de água doce, concomitante à aplicação injetável de levamisol, evidenciou eficácia terapêutica em diversos parâmetros após 14 dias de tratamento.

Digestibility, protein retention rate and ammonia excretion in juvenile fat snook (Centropomus parallelus) fed with different protein levels / Digestibilidade, taxa de retenção proteica e excreção de amônia em juvenis de robalo-peva (Centropomus parallelus) alimentados com rações com diferentes níveis de proteína

ABSTRACT: The aim of this study was to determine the level of dietary crude protein (CP) (480, 400, 440, 520 and 560g kg-1) in rations for juvenile II fat snook (Centropomus parallelus) that best promotes protein absorption and lower excretion of nitrogenous products. Three experiments were conducted: the first assessed the protein retention rate; the second evaluated ammonia excretion; and the third determined the best digestibility coefficient. The estimated protein retention rate showed a positive quadratic response to dietary CP with maximum retention at the 510.20g kg-1 protein level, and increasing levels of protein resulted in a greater total ammonia excretion rate in water. The mean apparent protein digestibility coefficient values increased with increasing levels of dietary protein up to 520g kg-1, where they stabilized. As determined by regression, the level of dietary CP that promotes the best digestibility was 495.62g kg-1.

RESUMO: O objetivo da pesquisa foi determinar o nível de proteína bruta na dieta (400, 440, 480, 520 e 560g kg-1), nas rações de juvenis II de robalo-peva (Centropomus parallelus), que promove melhor absorção de proteína e menor excreção de produtos nitrogenados. Foram realizados três experimentos. O primeiro avaliou a taxa de retenção de proteína, o segundo a excreção de amônia, e o terceiro determinou o melhor coeficiente de digestibilidade. Os dados foram analisados por meio de regressão exponencial. A taxa de retenção proteica, calculada pela equação, apresentou efeito quadrático positivo e o máximo de retenção com 510,20g kg-1 de proteína na dieta. O aumento dos níveis de proteína resultou em maiores taxas de excreção de amônia total na água. Os valores médios dos coeficientes de digestibilidade aparente da proteína foram aumentando com o aumento da proteína dietética até o nível de 520g kg-1 onde se estabilizou. O nível de proteína bruta na dieta, determinado pela equação de regressão, que promove a melhor digestibilidade é de 495,62g kg-1.