Abstract The freshwater/brackish amphipod Quadrivisio lutzi inhabits coastal lagoons, highly unstable environments subject to sudden inflow of marine water. Our aim was to evaluate how the genetic composition varies in these populations. Brazilian populations were compared by 16S rRNA and COI gene sequences. The genetic structure of four Rio de Janeiro amphipod populations was evaluated during the period of 2011-2019 by COI. Rio de Janeiro population was compared with Alagoas and São Paulo populations, which was genetically distinct, at species level (16S, d > 7%; COI, d >14%). The genetic structure in Rio de Janeiro showed the Imboassica subpopulation as the most divergent (Imboassica & Carapebus, F ST = 0.238), followed by Lagamar population (Lagamar & Carapebus, F ST = 0.049). The geographic distance and urbanization around these lagoons explain the degree of genetic isolation of these amphipod subpopulations. Paulista and Carapebus populations were not structured. Temporal variation in haplotype number and frequency were evident in both populations that were evaluated (Carapebus and Imboassica). Changes in salinity and water volume variation at these lagoons may be responsible for the observed changes in genetic composition, which may be the results of genetic drift effects over temporally fluctuating size subpopulations, without loss of genetic diversity.

Abstract Sensitivity to different concentrations (0-200 mgL-1) of the alkylating agent methyl methanesulfonate (MMS) was evaluated in the new potential invertebrate model, the amphipod Quadrivisio lutzi (Shoemaker, 1933) after 48 h of exposure in two separate bioassays. In the first bioassay (0, 50, 100 and 200 mgL-1 MMS), all amphipods at concentrations ≥ 50 mgL-1 MMS were dead before completing the 48 h of exposure, which was also observed in the second bioassay for concentrations ≥ 30 mgL-1 MMS. There was no significant effect of gender on average mortality. The median 48 h lethal concentration (LC50) was 23.6 mgL-1 MMS for Q. lutzi. Therefore, 1/3 or less of this concentration may be used for positive control in sublethal conditions. The high sensitivity of Q. lutzi to MMS is discussed in comparison to other invertebrates.

ABSTRACT The amphipod Quadrivisio lutzi (Shoemaker, 1933) (Maeridae) inhabits the coastal lagoons of southeastern Brazil, which are highly unstable environments. Drastic reduction in the abundance and distribution of this amphipod on these lagoons has been observed. The constant recovery of its populations suggests that this species may show a reproductive strategy that helps it to persist on these environments. Therefore, our aim was to study the reproductive biology of this species in Carapebus lagoon and to answer the question if its reproductive strategy contributes to a rapid population recovery. The size-range at sexual maturity was determined by the relative growth of the gnathopods and by the number of articles in antennal flagella. Brood size, egg diameter, size at first maturity and other relative reproductive parameters were obtained, which were compared to other species using a multivariate Principal Component Analysis (PCA). Females reach maturity at smaller size-range (2.9-3.9 mm body length (BL) than males (4.9 -5.9 mm BL). Mean egg diameter was small (0.35 ± 0.08 mm) and fecundity was high (20.2 ± 9.2 eggs/female; maximum 48 eggs). The relative reproductive parameters observed in Q. lutzi suggest it as iteroparous species. The PCA situated Q. lutzi within the species of high reproductive potential, characterized by small female size at first maturity, small egg diameter, large brood size and iteroparity, which have been largely considered adaptations that allow rapid recovery of population sizes. Therefore, we concluded that the reproductive strategy of this species contributes to its survival in the highly unstable Carapebus lagoon at southeastern Brazil.

Vinte e quatro amostras de material dentário de Tursiops truncatus oriundas da coleção do Laboratório de Mamíferos Marinhos (FURG-RS) foram avaliadas para determinar seu potencial como fonte de DNA para estudos genético-populacionais e sistemáticos. Todos os dentes foram submetidos a processos de desinfecção, trituração e desmineralização. A dentina obtida foi pesada previamente à extração de DNA, a qual foi avaliada através da amplificação de dois genes mitocondriais, através da técnica de PCR (Reação em Cadeia da Polimerase), utilizando oligonucleotídeos iniciadores universais. Obteve-se sucesso apenas na amplificação do gene Citocromo-b. Destes produtos obtiveram-se concentrações de 3-12 ng/µl para o material dentário, observando-se uma relação linear positiva com a quantidade em gramas utilizada na extração de DNA. Com o objetivo de eliminar a possibilidade de contaminação foi realizada uma análise SSCP (Polimorfismo Conformacional de Fita Simples) incluindo os controles positivos e amostras de pessoas envolvidas nas análises. Os padrões SSCP de T. truncatus obtidos diferiram das outras amostras, observando-se polimorfismo na região para os exemplares de T. truncatus analisados. Concluiu-se que é possível obter DNA mitocondrial para estudos genético-populacionais e taxonômicos a partir de material dentário de golfinhos.

Twenty-four teeth of Tursiops truncatus from the collection of the Marine Mammals Laboratory (FURG-RS) were analysed for their potential as DNA source for population genetic and taxonomic studies. All teeth were submitted to decontamination, grinding and demineralisation processes. Dentin powder was weighed for DNA extraction, which was evaluated by the amplification of two mitochondrial genes through PCR using universal primers. Cytochrome-b gene was amplified successfully. PCR products showed concentrations of 3-12 ng/µl for dentin powder, which was positively correlated to the quantity of dentin powder used for DNA extraction. To rule out contamination a SSCP was carried out including positive controls, and samples of humans involved in the analysis. The SSCP patterns for T. truncatus differed from all others, showing also polymorphism for the region. It was concluded that dentin was a good source of mtDNA for genetic studies in dolphins.