Evidence of metabolic microevolution of the limpet Nacella concinna to naturally high heavy metal levels in Antarctica.

The gastropod Nacella concinna is the most conspicuous macroinvertebrate of the intertidal zone of the Antarctic Peninsula and adjacent islands. Naturally high levels of copper and cadmium in coastal marine ecosystems are accumulated in N. concinna tissues. We aimed to study the effects of metal cations on N. concinna arginase in the context of possible adaptive microevolution. Gills and muscle had the highest argininolytic activity, which was concentrated in the cytosol in both tissues. Gills had the highest levels of arginase and may be involved in the systemic control of l-arginine levels. The relatively high argininolytic activity of the N. concinna muscular foot, with KM=25.3±3.4mmolL-1, may be involved in the control of l-arginine levels during phosphagen breakdown. N. concinna arginases showed the following preferences for metal cations: Ni2+>Mn2+>Co2+>Cu2+ in muscle and Mn2+>Cu2+ in gills. Cu2+ activation is a unique characteristic of N. concinna arginases, as copper is a potent arginase inhibitor. Cu2+ partly neutralized N. concinna arginase inhibition by Cd2+, worked synergistically in muscle arginase activation by Co2+ and neutralized muscle arginase activation by Ni2+. Mn2+ was able to activate muscle arginase in the presence of Fe3+ and Pb2+. The selection of arginases that are activated by Cu2+ and resistant to inhibition by Cd2+ in the presence of Cu2+ over evolutionary timescales may have favored N. concinna occupation of copper- and cadmium-rich niches.

Metabolic responses of the Antarctic fishes Notothenia rossii and Notothenia coriiceps to sewage pollution.

The present study aimed to assess the sewage effects of the Brazilian Antarctic Station Comandante Ferraz, Admiralty Bay, King George Island, on the hepatic metabolism (energetic, antioxidant, and arginase levels) and levels of plasma constituents of two Antarctic fish species Notothenia rossii and N. coriiceps. The bioassays were conducted under controlled temperature (0 °C) and salinity (35 psu), exposing the fish for 96 h, to sewage effluent diluted in seawater to 0.5 % (v/v). Liver homogenates were tested for the specific activities of the enzymes glucose-6-phosphatase (G6Pase), glycogen phosphorylase (GPase), hexokinase, citrate synthase, lactate dehydrogenase, malate dehydrogenase, glucose-6-phosphate dehydrogenase, superoxide dismutase, glutathione reductase, catalase, and arginase. Plasma levels of glucose, triacylglycerides, cholesterol, total protein, albumin, chloride, magnesium, calcium, and inorganic phosphate were also determined. In N. rossii, the decrease in citrate synthase and the increase in G6Pase and GPase suggested that the sewage effluent activated glycogenolysis and hepatic gluconeogenesis, whereas is N. coriiceps, only G6Pase levels were increased. In N. rossii, sewage effluent induced hypertriglyceridemia without modulating glucose plasma levels, in contrast to N. coriiceps, which developed hypoglycemia without elevating plasma triglyceride levels. The decrease in glutathione reductase levels in N. coriiceps and in superoxide dismutase and catalase in N. rossii suggest that these two species are susceptible to oxidative stress stemming from the production of reactive oxygen species. An increase in magnesium in N. rossii and a decrease in N. coriiceps showed that sewage effluent compromised the control of plasma levels of this cation. Although phylogenetically close, both species of Antarctic fish exhibited different metabolic responses to the sewage effluent, with N. coriiceps showing greater susceptibility to the toxic effects of the pollutants. The present study suggests that the biochemical responses of these two species are potential indicators of metabolic changes caused by sewage effluents.

Taxonomy of Cotylea (Platyhelminthes: Polycladida) from Cabo Frio, southeastern Brazil, with the description of a new species.

Polyclads are free-living Platyhelminthes with a simple, dorsoventrally flattened body and a much ramified intestine. In Brazil, 66 species are reported; only three from Rio de Janeiro State (RJ). The main objective of this study is to describe and illustrate coloration pattern, external morphology, reproductive system morphology and, when possible, biological and ecological aspects of species of the suborder Cotylea found in Cabo Frio, RJ. Of the 13 cotylean polyclad species found, Pseudobiceros pardalis, Cycloporus variegatus and Eurylepta aurantiaca are new records from the Brazilian coast and one species is new to science, Pseudoceros juani sp. nov. Feeding observations were made of four species. It is the first time that Lurymare utarum, Cycloporus gabriellae, C. variegatus and E. aurantiaca are illustrated with digital photographs of live specimens and histological preparations. This study increases to 70 the number of Brazilian Polycladida and to 14 the number of species known from Rio de Janeiro State. However, the knowledge about Polycladida in Brazil still has gaps, with great parts of the coast remaining unsampled. 

A new mini box corer for sampling muddy bottoms in antarctic shallow waters

A new Mini Box Corer (MBC-GEAMB) was developed for bottom sampling in Antarctic shallow waters down to 100 m depth from a small vessel. It consists of a detachable stainless steel box with a total sampling area of 0.0625 m², and a closing arm with a detachable blade without an external frame. MBC allowed stratified bottom sampling and good quality samples comparable to those obtained through diving. A comparison between the MBC-GEAMB and a 0.056 m²van Veen grab (VV) was undertaken for the benthic macrofaunal composition in Admiralty Bay, King George Island (Antarctica). MBC and VV samples were taken from three depths (20, 30 and 60m) in two sites. Total densities sampled with the MBC were up to 10 times higher than those obtained with van Veen grab. VV samples might lead to faunistic abundance underestimation compared to the MBC samples. Besides, MBC showed a higher performance on discriminating different sites as regards total macrofaunal density. It is suggested that MBC could be employed as an efficient remote sampling device for shallow-waters where direct sampling by SCUBA was not advisable.

Um novo Mini Box Corer (MBC-GEAMB) foi desenvolvido para amostragens de fundo em águas rasas antárticas até 100 metros de profundidade, a partir de embarcações pequenas. Consiste em uma caixa de aço inox destacável com uma área total de amostragem de 0,0625 m², e um braço de fechamento com uma lâmina destacável, sem um suporte externo. MBC permite a amostragem estratificada do sedimento de fundo com amostras de qualidade comparáveis àquelas obtidas através de mergulho autônomo. Uma comparação entre o MBC-GEAMB e um van Veen de área 0,056 m²(VV) foi realizada utilizando a composição da macrofauna bentônica na Baía do Almirantado, (Ilha Rei George, Antarctica). Amostragens com MBC e VV foram realizadas em três profundidades (20, 30 e 60m) em dois locais. As densidades totais obtidas com o MBC foram até 10 vezes maiores que as obtidas com o van Veen. Amostragens com VV tendem a subamostrar a abundância faunística em comparação com amostragens realizadas com o MBC. O MBC apresentou melhor capacidade de resolução para discriminar locais diferentes em relação à densidade total da macrofauna. O MBC pode ser utilizado como um amostrador remoto eficiente em águas rasas onde a amostragem por mergulho não é plausível.

Succession in rocky intertidal benthic communities in areas with different pollution levels at Guanabara Bay (RJ-Brazil)

O objetivo deste estudo foi descrever e comparar a sucessão das comunidades bentônicas da região entre-marés, em duas áreas na Baía de Guanabara, RJ, Brasil: Urca, uma área sujeita a moderado nível de poluição orgânica, e Catalão, uma área extremamente poluída. Em cada área, três transectos verticais foram raspados um mês antes do início do estudo, para se avaliar o recrutamento dos organismos (tratamento Recrutamento), enquanto três outros transectos foram monitorados sem manipulação (tratamento Monitoramento). A porcentagem de cobertura dos organismos foi avaliada pelo método de interseção. A composição específica e a abundância relativa dos organismos foram avaliadas mensalmente entre Setembro e Dezembro de 2000. Um total de 26 espécies foi encontrado na Urca, enquanto 13 foram encontradas no Catalão. Após quatro meses, a composição específica observada no recrutamento na Urca foi muito similar (76%) a observada no monitoramento. No Catalão, três meses de estudo foram suficientes para alcançar 70% de similaridade, aumentando para 80% no quarto mês. A porcentagem de cobertura dos organismos mais abundantes na Urca, não foi similar entre os transectos do monitoramento e do recrutamento, após os quatro meses do estudo (< 40%), enquanto que no Catalão, a similaridade foi de 72% já no segundo mês. A comunidade encontrada na área com alto grau de poluição orgânica (Catalão) recuperou mais rapidamente do que a comunidade da área com moderada poluição orgânica (Urca). A maior velocidade de desenvolvimento e recuperação da comunidade bentônica da área com alta poluição orgânica em relação à área menos poluída, pode estar relacionada, principalmente, à existência de comunidades mais simples e resilientes na área mais degradada