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.

Can we assess the ecological status of estuaries based on larval fish assemblages?

Fish larvae of four SE Brazilian estuaries were investigated to assess if the larval fish assemblages reflect the ecological status of estuaries. All samples were collected in the same water mass to guarantee similar natural water parameters, assuring that major differences among estuaries were related to anthropogenic pressures. Water temperature, oxygen, pH, chlorophyll a, faecal coliforms, nutrient load and total particulate matter were obtained at each sampling area. A pressure index was used to assess the overall anthropogenic pressures acting in each estuary. Results showed that fish larvae were sensitive to water contamination, reducing the diversity and especially exhibiting a high dominance of few species. Furthermore, this study reinforced the idea that the high sensitivity of fish larvae can increase the accuracy of the environmental assessments when tackling short-time events of hydrological controls (physical barriers and control of the freshwater input), representing an advance in the water ecological quality assessments.

Description and distribution of the larvae of two species of Fistulariidae (Teleostei, Syngnathiformes) in the southeastern Brazil / Descrição e distribuição das larvas de duas espécies da família Fistulariidae (Teleostei, Syngnathiformes) no sudeste do Brasil

Fistulariidae contains the single genus, Fistularia, with four species. Two of these species are recorded from Brazil: Fistularia petimba and F. tabacaria. This study describes larvae of these two species of Fistularia, recording their distribution along the southeastern Brazilian coast, which is limited in the north by Real River (12º S) and in the south by São Tomé Cape (22º S). Samples were collected using a bongo net with mesh apertures of 330 and 500 μm during three oceanographic cruises conducted on spring/98 (Central III), winter/99 (Bahia 1) and autumn/00 (Central IV). The net was towed obliquely and the maximum depth was 200 m. Larvae of F. petimba were the most abundant and most widely distributed within the study area, including the seamounts of the Vitória-Trindade Ridge. Larvae of F. tabacaria were recorded only between 14º S and 21º S.

A família Fistulariidae é composta por um único gênero, Fistularia, com quatro espécies; duas delas ocorrem na costa brasileira: Fistularia petimba e F. tabacaria. Este estudo descreve as larvas dessas duas espécies de Fistularia, registrando suas distribuições ao longo da costa sudeste brasileira, que é delimitada ao norte pelo Rio Real (12º S) e ao sul pelo Cabo de São Tomé (22º S). As amostras foram coletadas através de uma rede bongô com aberturas de malha de 330 e 500 μm durante três operações oceanográficas realizadas na primavera/98 (Central III), inverno/99 (Bahia 1) e outono/00 (Central IV). Os arrastos foram oblíquos até a profundidade máxima de 200 m. As larvas de F. petimba foram as mais abundantes, distribuindo-se por toda a área de estudo, incluindo os montes submersos do sistema Vitória-Trindade. Por outro lado, as larvas de F. tabacaria foram coletadas apenas entre as latitudes 14º S e 21º S.

First occurrence of Dolicholagus longirostris larvae (Maul 1948) (Osmeriformes, Bathylagidae) near the mouth of the Amazon River / Primeira ocorrência de larvas de Dolicholagus longirostris (Maul 1948) (Osmeriformes, Bathylagidae) próximas à foz do rio Amazona

The family Bathylagidae contains eight genera and 22 species, of which only five occur in the Southwest Atlantic. Until recently, only adult specimens of the bathylaginin Melanolagus bericoides had been recorded off southern Brazil, between the Santa Marta Cape and Rio Grande (31º S and 49º W). The present work reports the first occurrence of Dolicholagus longirostris larvae on the northern Brazilian coast, expanding its distribution in the Southwest Atlantic. The two specimens found were collected near the mouth of the Amazon River (02º 00' 19" N, 47º 03' 30" W, and 00º 49' 06" N, 46º 25' 09" W).

A família Bathylagidae apresenta oito gêneros e 22 espécies, sendo que apenas cinco destas espécies ocorrem no Atlântico Sudoeste. No sul do Brasil já havia sido registrada a ocorrência de exemplares adultos de Melanolagus bericoides entre o Cabo de Santa Marta e Rio Grande (31º S e 49º W). Este trabalho registra a primeira ocorrência de larvas de Dolicholagus longirostris na costa norte brasileira, ampliando sua distribuição no Atlântico Sudoeste. Os dois exemplares encontrados foram coletados na foz do Rio Amazonas (02º 00' 19" N, 47º 03' 30" W, e 00º 49' 06" N, 46º 25' 09" W).

Seasonal variation in fish larvae at the entrance of Guanabara Bay, Brazil

Devido a crescente ação antrópica a qual está sujeita e sua importância sócio-econômica, a baía de Guanabara vem despertando grande interesse na comunidade científica. O presente trabalho objetivou analisar a variação quali-quantitativa temporal das larvas de peixes, relacionar a densidade das larvas com o ciclo nictemeral e verificar a influência dos ciclos de maré. Foram realizadas coletas, em um ponto localizado na entrada da baía, em setembro de 1995 e março de 1996. As coletas ocorreram nas marés de enchente e vazante ao longo de três dias. Os arrastos foram oblíquos, utilizando uma rede do tipo bongô com malhas de 500 µm. Foi coletado um total de 42 táxons. As famílias Engraulidae (Cetengraulis edentulus e Anchoa lyolepis) e Clupeidae (Harengula jaguana) ocorreram em grandes densidades e dominaram nas duas campanhas. As maiores densidades de larvas de peixes ocorreram durante a campanha de março, que apresentou altas temperaturas e baixas salinidades. Observou-se um padrão nictemeral em relação a abundância de larvas, com altas densidades durante a noite e baixas durante o dia. Os altos índices de diversidade encontrados ressaltam a importância desse ecossistema para várias espécies de peixes.