Seston biomass in plankton assemblages in the Southwestern Atlantic Ocean: spatial, vertical, and temporal variations.

Bioseston is a heterogeneous assemblage of bacterioplankton, phytoplankton, zooplankton, and planktonic debris. A detailed knowledge of biosestons is essential for understanding the dynamics of trophic flows in marine ecosystems. The distributional features of seston biomass in plankton (micro- and mesoplankton) in the Southwest Atlantic Ocean (Rio de Janeiro State, Brazil) were analyzed using stratified samples gathered to a depth of 2,400 m during night time. The horizontal pattern of biomass distribution was analyzed vis-a-vis station depth during both wet and dry periods, with higher values recorded in the continental shelf than in the slope, confirming the terrestrial contribution of nutrient sources to the marine environment. This horizontal variation reinforces the occurrence of seasonal vortices in Cabo Frio and Cabo de São Tomé on the central coast of Brazil. Environmental variables reflect the hydrological signatures of the water masses along the Brazilian coast. The largest seston biomass was related to high temperatures, salinities, and low inorganic nutrient concentrations in tropical and South Atlantic central waters. The observed distribution patterns suggest that seston biomass in plankton in the region may be structured based on partitioned horizontal and vertical habitats and food resources.

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.

Vertical distribution and structure of copepod (Arthropoda: Copepoda) assemblages in two different seasons down to 1200 m in the tropical Southwestern Atlantic

The vertical distribution of copepod assemblages, ascertained from the surface down to 1,200 m, was investigated during two sampling periods (rainy and dry seasons), at four depths, in the oligotrophic waters of the southwestern Atlantic Ocean. Total density, diversity, and richness differed among sampling depths. Copepod density decreased with depth in the two sampling periods, with a maximum at 1 m and a slight decrease at 800 m. Higher diversities were observed at 250 m and 1,200 m during the rainy season and at 1 m and 1,200 m during the dry season. The maximum number of species was found at 1,200 m during the rainy season and at 1 m during the dry season. Various copepod assemblages were delimited in the water column in the two sampling periods. The deeper copepod assemblages occupied a wider range of depths. Salinity and temperature influenced the structure of copepod assemblages and reflected the hydrographic characteristics of the water masses in the region. Candacia pachydactyla (Dana, 1849), Scolecithrix danae (Lubbock, 1856), and Agetus limbatus (Brady, 1883) were the indicator species found at 1 m. The effects of different environmental factors on the copepod assemblages suggest that these consortia occupy distinct niches in the ocean.

Vertical distribution and structure of copepod (Arthropoda: Copepoda) assemblages in two different seasons down to 1200 m in the tropical Southwestern Atlantic

The vertical distribution of copepod assemblages, ascertained from the surface down to 1,200 m, was investigated during two sampling periods (rainy and dry seasons), at four depths, in the oligotrophic waters of the southwestern Atlantic Ocean. Total density, diversity, and richness differed among sampling depths. Copepod density decreased with depth in the two sampling periods, with a maximum at 1 m and a slight decrease at 800 m. Higher diversities were observed at 250 m and 1,200 m during the rainy season and at 1 m and 1,200 m during the dry season. The maximum number of species was found at 1,200 m during the rainy season and at 1 m during the dry season. Various copepod assemblages were delimited in the water column in the two sampling periods. The deeper copepod assemblages occupied a wider range of depths. Salinity and temperature influenced the structure of copepod assemblages and reflected the hydrographic characteristics of the water masses in the region. Candacia pachydactyla (Dana, 1849), Scolecithrix danae (Lubbock, 1856), and Agetus limbatus (Brady, 1883) were the indicator species found at 1 m. The effects of different environmental factors on the copepod assemblages suggest that these consortia occupy distinct niches in the ocean.(AU)

Analysis of the Appendicularia class (subphylum Urochordata) as a possible tool for biomonitoring four estuaries of the tropical region.

This study aims to characterize the differences between physical and chemical parameters of water quality indicators and eutrophication in four estuaries of the state of Rio de Janeiro and relate them to full density of the species that belong to the Appendicularia class with the purpose of seeking bioindicators for estuarine areas. The estuaries studied were from the rivers Macaé, São João, Bracuí, and Perequê-Açu. The physicochemical parameters monitored for evaluation of the water bodies and used for the correlation with the appendicularians were pH, temperature, nitrite, nitrate, N-ammonia, total nitrogen, phosphate, total phosphorus, dissolved oxygen (DO), suspended particulate matter (SPM), chlorophyll a, heterotrophic bacteria, and fecal coliform. The estuaries Bracuí and São João showed enhanced qualities of water and lower degrees of eutrophication than Macae and Perequê-Açu estuaries. The species of the Appendicularia class found in this study were Oikopleura longicauda (Vogt, 1854), Oikopleura dioica Fol, 1872, Oikopleura fusiformis Fol, 1872, and Fritillaria haplostoma Fol, 1872. The density of appendicularians and O. longicauda was inversely related to the nutrient values and SPM; nonetheless, no species of appendicularians could be used as a bioindicator of any estuary in the current study. Studies on the quality of estuary waters and the search for other bioindicators belonging to other zooplankton groups are recommended to confirm the obtained results and to expand the knowledge of these coastal environments.

Inter-annual variability of planktonic copepods in a tropical bay in southeastern Brazil

The aim of this work was to study the structure of the copepod community in relation to hydrographic conditions in Espírito Santo Bay, from 1993 to 1997. Zooplankton samples were obtained in the horizontal tows four times a year, using a 200 µm net. Temperature, salinity and dissolved oxygen were determined in the water samples. The overall mean density of the copepods was 9,085 ind.m-3 with the peaks exceeding 15,000 ind.m-3 in the summer and autumn during the first three years (1993 - 1995). The PCA analysis was used to relate the environmental conditions with the distribution of the copepods. The increases in the abundant species, namely Acartia lilljeborgi, Oithona hebes, Oithona oculata, Paracalanus quasimodo, Parvocalanus crassirostris and Euterpina acutifrons, were related to the decreases in the diversity. The spatial and temporal variations of the temperature and salinity influenced the abundance of the species during the five years of the sampling and the dominant species alternated in abundance.

Este trabalho descreve a estrutura da comunidade de copépodes em relação às condições hidrográficas da baía do Espírito Santo, no período de 1993 a 1997. As amostras do zooplâncton foram obtidas através de arrastos horizontais, quatro vezes ao ano, com uma rede de 200µm. A temperatura, a salinidade e o oxigênio dissolvido foram determinados nas amostras de água. A densidade média dos copépodes foi de 9.085 ind.m-3, com picos superiores a 15.000 ind.m-3, durante o verão e o outono de 1993 a 1995. Utilizou-se a PCA para relacionar as variáveis ambientais à distribuição dos copépodes. A comunidade dos copépodes, principalmente as altas densidades das espécies Acartia lilljeborgi, Oithona hebes, Oithona oculata, Paracalanus quasimodo, Parvocalanus crassirostris e Euterpina acutifrons foram relacionados à diminuição da diversidade. As variações espaço-temporais da temperatura e da salinidade influenciaram a abundância das espécies durante os cinco anos de coleta, com a alternância das espécies dominantes.

New records of Monstrilloida Sars, 1901 (Crustacea: Copepoda) from Rio Grande do Norte (northeastern coast of Brazil) / Novas ocorrências para Monstrilloida Sars, 1901 (Crustacea: Copepoda) do Rio Grande do Norte (costa nordeste do Brasil)

During a series of zooplankton surveys carried out during 1984, off the south coast of the state of Rio Grande do Norte, Brazil, several species of monstrilloids were present in the samples. A total of 50 individuals of monstrilloid copepods were collected. These belong to four species (Monstrilla brasiliensis Suárez-Morales & Dias, Cymbasoma cf. longispinosum, Cymbasoma cf. rigidum, and Cymbasoma gracilis Gurney). The taxonomic complexes formed by the species C. cf. longispinosum and C. cf. rigidum in Brazilian waters are discussed. The lengths of the specimens are provided in order to contribute to studies and revisions of the specimens belonging to these species-complexes. The species Monstrilla brasiliensis is recorded for the first time in the Rio Grande do Norte coastal region, thus expanding its geographical range in the Brazilian northeastern coast. The results presented herein increase to four the number of species of Monstrilloida known from off Rio Grande do Norte state.

Durante uma série de amostragens de zooplâncton, realizadas durante o ano de 1984, na costa sul do estado do Rio Grande do Norte, Brasil, um total de 50 exemplares de copépodes Monstrilloida foram coletados. Os exemplares pertencem a quatro espécies (Monstrilla brasiliensis Suárez-Morales & Dias, Cymbasoma cf. longispinosum, Cymbasoma cf. rigidum and Cymbasoma gracilis Gurney). Os complexos taxonômicos formados pelas espécies C. cf. longispinosum e C. cf. rigidum em águas brasileiras são discutidos. Os comprimentos totais dos exemplares são fornecidos com a finalidade de contribuir com futuros estudos e revisões dos espécimes pertencentes a estes complexos de espécies. A espécie Monstrilla brasiliensis foi coletada pela primeira vez na região costeira do estado do Rio Grande do Norte, expandindo a sua distribuição geográfica na costa nordeste brasileira. Os resultados apresentados aumentam a quatro o número de espécies de Monstrilloida conhecidas para a costa do estado do Rio Grande do Norte.

New records of Monstrilloida Sars, 1901 (Crustacea, Copepoda) on the Brazilian northeastern coast / Novas ocorrências para Monstrilloida Sars, 1901 (Crustacea, Copepoda) na costa Nordeste do Brasil

During a series of zooplankton surveys carried out from 2001 through 2005 off the coast of the state of Bahia, Brazil, 98 individuals of monstrilloid copepods were collected. These belong to five species (Monstrilla grandis, Cymbasoma cf. longispinosum, Cymbasoma cf. rigidum, Cymbasoma gracilis, and Cymbasoma quadridens). The first three are recorded for the first time in the Bahia coastal region. The geographical range of C. quadridens is expanded to the Brazilian northeastern coast. The results presented herein increase to nine the number of nominal species of Monstrilloida known from off Bahia; the environmental diversity of Caravelas Channel with highly productive areas and coral reef zones harbor an abundant and diverse monstrilloid fauna that should be surveyed in more detail.

Durante uma série de amostragens de zooplâncton, realizadas de 2001 a 2005, na costa do estado de Bahia, Brasil, 98 exemplares de copépodes Monstrilloida foram coletados. Os exemplares pertencem a cinco espécies (Monstrilla grandis, Cymbasoma cf. longispinosum, Cymbasoma cf. rigidum, Cymbasoma gracilis and Cymbasoma quadridens). As primeiras três espécies foram coletadas pela primeira vez na região costeira do estado da Bahia. A distribuição geográfica de C. quadridens foi expandida para a costa nordeste brasileira. Os resultados apresentados aumentam a nove o número de espécies Monstrilloida conhecidas para a costa da Bahia. A diversidade ambiental do Canal de Caravelas, com áreas altamente produtivas e a proximidade de uma região de recifes de coral, abriga uma abundante e diversa fauna de Monstrilloida, que deve ser examinada mais detalhadamente.

Occurrence of Euchaeta paraconcinna Fleminger, 1957 (Crustacea, Copepoda, Calanoida) in a coastal area of Bahia State, northeastern Brazil / Ocorrência de Euchaeta paraconcinna Fleminger, 1957 (Crustacea, Copepoda, Calanoida) em uma região costeira do estado da Bahia, Nordeste do Brasil

The calanoid copepod Euchaeta paraconcinna Fleminger, 1957 is reported from Camamu Bay, state of Bahia, northeastern Brazil (14º02'49"S; 38º52'58"W). Three females were collected by vertical hauls with a plankton net of 200 'm mesh size. This is a new record for this species in northeastern Brazil.

Uma nova ocorrência para o copépode Calanoida Euchaeta paraconcinna Fleminger, 1957 foi registrada na região costeira da baía de Camamu, estado da Bahia, Nordeste do Brasil (14º02'49"S; 38º52'58"W). Três fêmeas foram coletadas em arrastos verticais, com rede de plâncton, de 200 'm de malha. Este registro revela uma nova ocorrência desta espécie no Nordeste do Brasil.