Mixed-stock analysis in green turtles Chelonia mydas: mtDNA decipher current connections among west Atlantic populations.

The green turtle Chelonia mydas undertakes wide-ranging migrations between feeding and nesting sites, resulting in mixing and isolation of genetic stocks. We used mtDNA control region to characterize the genetic composition, population structure, and natal origins of C. mydas in the West Atlantic Ocean, at one feeding ground (State of Rio de Janeiro, Brazil), and three Caribbean nesting grounds (French Guiana, Guadeloupe, and Suriname). The feeding ground presented considerable frequency of common haplotypes from the South Atlantic, whereas the nesting sites presented a major contribution of the most common haplotype from the Caribbean. MSA revealed multiple origins of individuals at the feeding ground, notably from Ascension Island, Guinea Bissau, and French Guiana. This study enables a better understanding of the dispersion patterns and highlights the importance of connecting both nesting and feeding areas. Effective conservation initiatives need to encompass these ecologically and geographically distinct sites as well as those corridors connecting them.

Green turtle (Chelonia mydas) genetic diversity at Paranaguá Estuarine Complex feeding grounds in Brazil.

Sea turtles are marine reptiles that undertake long migrations through their life, with limited information regarding juvenile stages. Feeding grounds (FGs), where they spend most of their lives, are composed by individuals from different natal origins, known as mixed stock populations. The aim of this study was to assess genetic composition, natal origins and demographic history of juvenile green turtles (Chelonia mydas) at the Paranaguá Estuarine Complex (PEC), Brazil, considered a Natural World Heritage site. Tissue samples of stranded animals were collected (n = 60), and 700 bp mitochondrial DNA sequences were generated and compared to shorter sequences from previously published studies. Global exact tests of differentiation revealed significant differences among PEC and the other FGs, except those at the South Atlantic Ocean. Green turtles at PEC present genetic signatures similar to those of nesting females from Ascension Island, Guinea Bissau and Aves Island/Surinam. Population expansion was evidenced to have occurred 20-25 kYA, reinforcing the hypothesis of recovery from Southern Atlantic refugia after the last Glacial Maximum. These results contribute to a better understanding of the dynamics of green turtle populations at a protected area by providing knowledge on the dispersion patterns and reinforcing the importance of the interconnectivity between nesting and foraging populations.

Efeitos do Chumbo no metabolismo do camarão branco(Litopenaeus schmitti) em relação à salinidade / Effects of Lead in white shrimp (Litopenaeusschmitti) metabolism regarding salinity

Os camarões penaeus são importantes recursos da indústria de pesca mundiais e da aquacultura. No Brasil, Litopenaeusschmitti é uma espécie importante comercialmente explorada e o animal ideal para estudar o prejuízo causado pelos efeitosde metais pesados frequentemente descobertos em áreas costeiras. O objetivo principal do presente estudo foi descobrira toxicidade aguda do chumbo (Pb) em L. schmitti e investigar o seu efeito sobre o consumo de oxigênio e a excreçãode amônia em diferentes salinidades. Não se estudou esse efeito nessa espécie antes. O chumbo foi significativamentemais tóxico na salinidade 8 do que 20 e 33. O consumo de oxigênio e a excreção de amônia previram-se por meio deexperimentos executados em cada uma de quinze combinações possíveis de três salinidades (33, 20 e 8), na temperaturade 21 °C. O cádmio mostrou uma melhora significativa no consumo de oxigênio na salinidade 8, e os resultados mostramque o consumo de oxigênio aumenta com respeito à concentração de chumbo. No momento da concentração de chumbomais alta empregada (2.12 10-2 mg/L), a salinidade 8 e a temperatura em 21 °C, o consumo de oxigênio aumentou 131%em relação ao controle. Além disso, depois da exposição separada ao chumbo, verificou-se que o chumbo é mais tóxicopara L. schmitti na salinidade mais baixa.

Penaeid shrimps are important resources for worldwide fisheries and aquaculture. In Brazil, Litopenaeus schmitti is animportant commercially exploited species, and the ideal animal for studying the impairment caused by the effects ofheavy metals often detected in coastal areas. The main purpose of the present study was to detect the acute toxicity of lead(Pb) in L. schmitti and to investigate its effect on oxygen consumption and ammonia excretion for different salinities. Thishas not been studied in this species before. Lead was significantly more toxic at salinity 8 than at 20 and 33. The oxygenconsumption and ammonia excretion were estimated through experiments performed on each of the fifteen possiblecombinations of three salinities (33, 20 and 8), at the temperature of 21 °C. Cadmium showed a significant improvementin oxygen consumption at salinity 8, and results show that the oxygen consumption increases with respect to the leadconcentration. At the highest lead concentration employed (2.12 10-2 mg/L), the salinity 8 and the temperature at 21 °C,oxygen consumption increases 131% in relation to the control. In addition, after separate exposure to lead, elevation inammonia excretion was obtained, which was 88.2% higher than the control. The results show that lead is more toxic to L.schmitti at lower salinities.

The interplay of homing and dispersal in green turtles: a focus on the southwestern atlantic.

Current understanding of spatial ecology is insufficient in many threatened marine species, failing to provide a solid basis for conservation and management. To address this issue for globally endangered green turtles, we investigated their population distribution by sequencing a mitochondrial control region segment from the Rocas Atoll courtship area (n = 30 males) and four feeding grounds (FGs) in Brazil (n = 397), and compared our findings to published data (n (nesting) = 1205; n (feeding) = 1587). At Rocas Atoll, the first Atlantic courtship area sequenced to date, we found males were differentiated from local juveniles but not from nesting females. In combination with tag data, this indicates possible male philopatry. The most common haplotypes detected at the study sites were CMA-08 and CMA-05, and significant temporal variation was not revealed. Although feeding grounds were differentiated overall, intra-regional structure was less pronounced. Ascension was the primary natal source of the study FGs, with Surinam and Trindade as secondary sources. The study clarified the primary connectivity between Trindade and Brazil. Possible linkages to African populations were considered, but there was insufficient resolution to conclusively determine this connection. The distribution of FG haplotype lineages was nonrandom and indicative of regional clustering. The study investigated impacts of population size, geographic distance, ocean currents, and juvenile natal homing on connectivity, addressed calls for increased genetic sampling in the southwestern Atlantic, and provided data important for conservation of globally endangered green turtles.