Time filter

Source Type

Di Tullio J.C.,Grande Rio University | Gandra T.B.R.,Federal University of Rio Grande do Sul | Zerbini A.N.,Cascadia Research Collective | Zerbini A.N.,National Oceanic and Atmospheric Administration | And 2 more authors.
PLoS ONE | Year: 2016

Temporal and spatial patterns of cetacean diversity and distribution were investigated through eight ship-based surveys carried out during spring and autumn between 2009 and 2014 on the outer continental shelf (∼150m) and slope (1500m) off southeastern and southern Brazil (∼23°S to ∼34°S). The survey area was divided into southeast and south areas according to their oceanographic characteristics. Twenty-one species were observed in 503 sightings. The overall number of species was similar between the two areas, though it was higher in the spring in the south area. Five species were dominant and diversity varied more seasonally than spatially. ANOVA and kernel analyses showed that overall cetacean densities were higher in spring compared to autumn. Physeter macrocephalus, the most frequent species, concentrated throughout the south area at depths over 1000m in both seasons. Despite the overlapped occurrence at a broader scale, small delphinids presented latitudinal and in-offshore gradients as well as seasonal variation in distribution patterns, which could indicate habitat partitioning between some species. Delphinus delphis was only recorded in the south and its density decreased in areas where the presence of Stenella frontalis increased, mainly beyond the 250m isobath. Densities of S. longirostris and S. attenuata increased in lower latitudes and beyond the shelf break. The large delphinids Tursiops truncatus and Globicephala melas formed mixed groups in many occasions and were observed along the study area around depths of 500m. Grampus griseus was twice as frequent in the south area and densities increased in waters deeper than 600m. As expected, densities of both small and large migratory whales were higher during spring, over the continental slope, in the southeast area. The results presented here provided strong evidence on the importance of the outer continental shelf and slope to a diverse community of cetaceans occurring in the subtropical Southwestern Atlantic. © 2016 Di Tullio et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Zerbini A.N.,National Oceanic and Atmospheric Administration | Zerbini A.N.,Instituto Aqualie | Clapham P.J.,National Oceanic and Atmospheric Administration | Wade P.R.,National Oceanic and Atmospheric Administration
Marine Biology | Year: 2010

The rate of growth of any population is a quantity of interest in conservation and management and is constrained by biological factors. In this study, recent data on life-history parameters influencing rates of population growth in humpback whales, including survival, age at first parturition and calving rate are reviewed. Monte Carlo simulations are used to compute a distribution of rates of increase (ROIs) taking into account uncertainty in biological parameter estimates. Two approaches for computing juvenile survival are proposed, which taken into account along with other life-history data, resulted in the following estimates of the rate of population growth: Approach A: mean of 7.3%/year (95% CI = 3.5-10.5%/year) and Approach B: mean of 8.6%/year (95% CI = 5.0-11. 4%/year). It is proposed that the upper 99% quantile of the resulting distribution of the ROI for Approach B (11.8%/year) be established as the maximum plausible ROI for humpback whales and be used in population assessment of the species. Possible sources of positive and negative biases in the present estimates are presented and include measurement error in estimation of life-history parameters, changes in the environment within the period these quantities are measured, density dependence or other natural factors. However, it is difficult to evaluate potential biases without additional data. The methods presented in this study can be applied to other species for which life-history parameters are available and are useful in assessing plausibility in the estimation of population growth rates from time series of abundance estimates. © 2010 Springer-Verlag.

Rodrigo H.O.,Federal Rural University of Rio de Janeiro | Especie M.A.,Federal Rural University of Rio de Janeiro | Lodi L.,Instituto Aqualie | Simao S.M.,Federal Rural University of Rio de Janeiro
Zoologia | Year: 2013

Parental care is any form of parental behavior that increases offspring fitness. To the authors' knowledge, this study is the first to analyze the intensity of parental care in the Guiana dolphin, Sotalia guianensis (van Bénéden, 1864). The objectives of this study are as follows: 1) to quantify the degree of parental care in S. guianensis in Ilha Grande Bay, Rio de Janeiro; 2) to investigate the influence of behavioral state and group size on the degree of parental care; and 3) to evaluate the differences between the intensity of parental care provided to calves and juveniles. Our results indicate that the intensity of parental care is high in S. guianensis and that care is more intense in larger groups. It is possible that these differences serve to maximize hydrodynamic gains and to minimize risks. Our results suggest that parental care is more intense during travel. A possible reason for this greater intensity is that the feeding dynamics show a more random pattern than other behavioral states. Moreover, the results indicate that calves receive more intense care than juveniles. These results suggest that parent-offspring conflict is possible in the study population. © 2013 Sociedade Brasileira de Zoologia.

Lodi L.,Instituto Aqualie | Farias-Junior S.,Projeto Golfinhos
Pan-American Journal of Aquatic Sciences | Year: 2011

This note reports eleven new sightings of a previously identified male killer whale (Orcinus orca) between Mongaguá, São Paulo State and Saquarema, Rio de Janeiro State, between 1999 and 2010. These observations suggest the existence of site fidelity within these areas.

Barbieri F.,University of the Rio dos Sinos Valley | Machado R.,University of the Rio dos Sinos Valley | Zappes C.A.,State University of Norte Fluminense | Zappes C.A.,Instituto Aqualie | And 2 more authors.
Ocean and Coastal Management | Year: 2012

The Neotropical otter (Lontra longicaudis) is an aquatic carnivore that interacts with fisheries activities and competes with fisherman for resources. Information about the biology and conservation issues of a species can be obtained from traditional ecological knowledge collected from the communities that share the same resources. In this sense, the objective of this study was to describe conflicts between the otters and two fishing communities (Imbé and Tramandaí) in the Tramandaí Lagoon (29°57'S; 50°11'W), in southern Brazil. We conducted 36 interviews that represented 72% of the local fishermen that use gillnets in the lagoon. All fishermen reported that otters interfered with fishing activities, by feeding on fish in the gillnets, and 75% of those interviewed reported gear damage. Fifty percent of the fishermen reported that observed the otters used the lagoon daily. Many fishermen (41.6%) also reported that the amount of damage attributed to the otters was considered " small" , but the depredation was reported as occurring daily (55.5%). Fishermen from Imbé have a more negative perception of the interaction with otters, probably because they usually fish near to the area most frequently used by otters. This amplifies the magnitude of the conflict and damage. In order to minimize the depredation of fish by otters directly on the gillnets, we suggested some measures to fishery management, as well as additional studies about the potential prey overlap between the Neotropical otter and the fishery. © 2012 Elsevier Ltd.

Discover hidden collaborations