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... Con relación a las especies de mamíferos acuáticos que habitan nuestro país, se han hecho avances importantes en describir aspectos como uso de hábitat, distribución, abundancia, comportamiento, dieta, contaminantes, interacciones con pesquerías, impacto del turismo, cacería dirigida, contaminación acústica, patógenos, amenazas e impactos y cambios en la ecología del movimiento (Prieto-Rodríguez 1988;Vidal 1990;Flórez-González, 1991;Trujillo, 1992;Vidal et ál., 1994;Flórez-González & Capella 1995;Mora-Pinto et ál., 1995;Capella et ál., 2001Capella et ál., , 2007aCaballero et ál., 2001Caballero et ál., , 2010Caballero et ál., , 2015Caballero et ál., , 2018Diazgranados & Trujillo, 2002;Kendall & Orozco 2003;Botello 2004;García & Trujillo, 2004;Trujillo & Diazgranados, 2004;Carrasquilla & Trujillo, 2004;Holguín et ál., 2005;Pardo & Palacios 2006;Vianna et ál., 2006;Castelblanco-Martínez et ál., 2009Pardo et ál., 2009;Fraija et ál., 2009;Mayor-Victoria & Botero-Botero 2010a,b;Jiménez-Pinedo et ál., 2011;Herrera et ál., 2011;Morales & Jáuregui 2012;Palacios et ál., 2012;Restrepo & Botero-Botero 2012;Satizábal et ál., 2012;Mosquera-Guerra et ál., 2015, 2018a, 2019aTrujillo et ál., 2013;Arévalo-González et ál., 2014;Kendall et ál., 2014;Mojica-Figueroa et ál., 2014;Van Bressem et ál., 2015;Botero-Botero et ál., 2016Farías-Curtidor et ál., 2017;Perazio et ál., 2018;Barragán-Barrera et ál., 2019Vélez et ál., 2019;Ávila et ál., 2008, 2017Méndez-Fernández et ál., 2020). ...
... Respecto a la ballena jorobada, se ha identificado que aproximadamente el 1,9% de la población de ballenas jorobadas de Colombia está afectada por enmallamientos con redes de pesca, con un promedio de 2,3 (±1,8) enmallamientos por año, 60% de los casos involucraron crías (Capella et ál., 2001(Capella et ál., , 2007a. El tucuxi marino ha sido afectado por enmallamientos en el Golfo de Salamanca y en cercanías a Santa Marta (Pardo & Palacios 2006 Figura 1. Mapa de riesgo para todas las especies de mamíferos marinos basados en las amenazas reportadas. Este mapa muestra la proporción de especies con al menos una amenaza del total de especies presentes en cada celda. ...
... Estas exploraciones sísmicas incluyen la producción de fuertes explosiones e intensos sonidos usando detonaciones en serie, los cuáles son fácilmente detectados a más de 10 km de distancia y tienen efectos potencialmente perjudiciales sobre los mamíferos marinos, entre los cuales están el estrés y la confusión, cambios en el comportamiento y la vocalización, el movimiento de los animales de sus zonas de reproducción, daños auditivos y la mortalidad (Gordon et ál., 2003). Adicionalmente, se reporta en los años 90s un varamiento de dos delfines manchados del Atlántico (S. frontalis; un adulto y un juvenil) en cercanías de Santa Marta relacionado con la contaminación resultante de la pesca con dinamita (Pardo & Palacios, 2006). La pesca con dinamita también se asocia con la reducción del hábitat de la nutria neotropical (L. ...
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Trujillo, F., Caicedo, D., Diazgranados, M.C. & I.C. Avila. (2022). Plan de Acción Nacional para la Conservación de los Mamíferos Acuáticos de Colombia 2022-2035. In: Avello-Castiblanco, G.C., González-Delgadillo, A.M., Quintero-Gil, J.A. (Eds.) Ministerio de Ambiente y Desarrollo Sostenible, Bogotá, DC. Colombia. 96p. ISBN: 978-958-5551-82-4.
... For example, Best (2001) documented distinct Bryde's whale populations along the southern coast of Africa that included a resident non-migratory population over the South Africa continental shelf and a pelagic population that migrated seasonally along the southwestern African coast. Non-migratory populations also occur in the Gulf of Haurki, New Zealand (Kato & Perrin 2009, Izadi et al. 2018, off the coast of Colombia (Pardo & Palacios 2006), southeastern Brazil (Lodi et al. 2015), and in the Gulf of California (Salvadeo et al. 2011). Seasonal range expansion and contraction, similar to that observed along the western coast of Africa, occurs in the Southern California Bight (Kerosky et al. 2012), and larger-scale seasonal movements likely occur in the western North Pacific (Watanabe et al. 2012). ...
... Many of these prey species are associated with localized upwelling (e.g. Pardo & Palacios 2006, Weir et al. 2012, Tardin et al. 2017. Both the whales and their prey therefore occur where physiographic features, such as the continental shelf break (Corkeron et al. 2011), or oceanographic features, such as the Benguela Current along the African coast (Weir et al. 2012) and the Kuroshio Front in the western Pacific (Watanabe et al. 2012), maintain persistent upwelling and high prey density. ...
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The newly recognized Rice’s whale Balaenoptera ricei is among the most endangered large whale species in the world and primarily occupies a region near the continental shelf break in the northeastern Gulf of Mexico (GoMex). We analyzed visual line-transect survey data collected throughout the northern GoMex from 2003-2019 and developed spatially explicit density maps using a density surface modeling approach to examine relationships between Rice’s whale density and bathymetric and oceanographic features. We identified water depth, surface chl a concentration, bottom temperature, and bottom salinity as key parameters that define the Rice’s whale habitat. This is consistent with upwelling of cold, high-salinity water along the continental shelf break and seasonal input of high-productivity surface water originating from coastal sources. The dominant circulation patterns in the GoMex, including the presence of Loop Current eddies, lead to increased productivity and likely play a role in maintaining high densities of forage species needed to support Rice’s whales. Extrapolation of the model suggests additional regions in Mexican waters of GoMex that may be suitable for Rice’s whales. This study informs the designation of critical habitat as defined by the US Endangered Species Act and will assist in marine spatial planning activities to avoid additional anthropogenic impacts to Rice’s whales associated with the development of wind energy and aquaculture.
... Stationary platforms can be excellent to conduct low-cost long-monitoring programs. Although the sampling area covered is small relative to that in other methods, outpost at heights greater than 20 m above sea level have been demonstrated to improve the method, with an effective radial field-of-view of ,2000 m (Pardo and Palacios 2006). This method was used to observe cetaceans in coastal areas of Venezuela and Colombia (Table S1). ...
... Boat-based surveys can be conducted from a variety of boats equipped with outboard engines or catamaran sail ships. The speeds vary from low speed rates (,5 km h -1 or drifting with the engine off) for manatee studies, and among 10 and 15 km h -1 for cetaceans (Pardo and Palacios 2006). As a complement of this method, side-scan sonar has proven to be a valuable tool that can assist scientists and managers to detect manatees in complex waterways, especially in freshwater systems (Gonzalez-Socoloske et al. 2009). ...
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The Caribbean is a mega-diverse and bio-geographically important region that consists of the Caribbean Sea, its islands, and surrounding coastlines. Among the billions of aquatic species inhabiting this region, the mega-vertebrates stand out for their social, economic and ecologic relevance. However, the Caribbean has been threatened by climate change, poverty, pollution, environmental degradation and intense growth of the tourism industry, affecting megafauna species directly and indirectly. Population monitoring plays a critical role in an informed conservation process and helps guide management decisions at several scales. The aim of the present review was to critically examine the methods employed for monitoring marine megafauna in the Caribbean, so as to create a framework for future monitoring efforts. In total, 235 documents describing protocols for the monitoring of sirenians, cetaceans, elasmobranchs, sea turtles and crocodilians in the Caribbean region, were reviewed. The methods included community-based monitoring (interviews, citizen science and fisheries monitoring), aerial surveys (by manned and unmanned aerial vehicles), boat-based surveys (including manta tow, and side-scan sonars), land-based surveys, acoustic monitoring, underwater surveys, baited remote underwater video, mark–recapture, photo-identification and telemetry. Monitoring efforts invested on aquatic megafauna in the Caribbean have been highly different, with some species and/or groups being prioritised over others. The present critical review provides a country-based overview of the current and emerging methods for monitoring marine megafauna and a critical evaluation of their known advantages, disadvantages and biases.
... Additionally, samples from the Caribbean basin, coming from Colombia and Puerto Rico, were included in this study (Fig. 1). Samples from Colombia were collected from two locations: 1) in waters of Dibulla, located in La Guajira Peninsula on the northern portion of Colombia, where four samples of free-ranging adult individuals from a group of around 15 dolphins were collected on May 19 th , 2015 ( Herrera, 2008;Fajardo, 1979;Gutiérrez et al., 2015), so cetaceans have been usually reported there (e.g., Barragán-Barrera, do Amaral, et al., 2019, Barragán-Barrera, Luna-Acosta, et al., 2019Fraija et al., 2009;Pardo & Palacios, 2006). Regarding Puerto Rico, it is a Caribbean archipelago that is part of the Greater Antilles ( Fig. 1), and due its localization between the Caribbean Sea and the Atlantic Ocean, holds a high marine mammals' diversity in the Wider Caribbean (Mignucci-Giannoni, 1989). ...
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Introduction: The rough-toothed dolphin (Steno bredanensis) inhabits oceanic waters of tropical latitudes and exhibits philopatry in some oceanic islands. However, the species has been observed in shallow coastal waters in a few areas. Particularly in Central America, the rough-toothed dolphin has been reported by occasional records and strandings. For instance, the first confirmed record of this species in the Panama’s Caribbean was on July 17, 2012, in a coastal region of the Chiriquí Lagoon during a bottlenose dolphin monitoring survey. Similarly, the first rough-toothed dolphin mass stranding reported for the Pacific of Panama was on April 20, 2016, at the Ostional Beach, where 60 dolphins stranded and ten died. These sightings and events offered a valuable opportunity to obtain samples to conduct genetic studies, which are scarce in the region. Objective: In this study, we present the first assessment of genetic diversity for rough-toothed dolphins based on mitochondrial DNA Control Region (mtDNA-CR) in the Panamanian Pacific and the Wider Caribbean. Methods: Samples were collected in Colombia (N=5), Panama (N-Caribbean=1, N-Pacific=9), and Puerto Rico (N=3) from free-ranging and stranded individuals. DNA was extracted from each sample, and a mtDNA segment of around 534 to 748 bp was amplified through the PCR reaction. The obtained sequences were compared with rough-toothed dolphin haplotypes previously published in NCBI (N=70), from the Atlantic, Indian, and the Pacific Oceans. Results: Our findings showed significant population structure among ocean basins (strong differentiation with ΦST data), and high genetic diversity within each phylogroup. Only the Atlantic Ocean showed high genetic differentiation within the basin, detecting three phylogroups: the Caribbean, northern, and southern Atlantic. Conclusions: These findings support previous genetic studies that indicate high levels of population structure among ocean basins, although this species seems to be widely dispersed. However, samples from Panama and the Caribbean appear to show connectivity between highly differentiated Atlantic and Pacific Oceans. Therefore, our results highlight the need for more research to assess the rough-toothed dolphin genetic and population status in Central America, as the piece of the puzzle needed to clarify its taxonomy and genetic differentiation worldwide. This information is needed due to the rough-toothed dolphin IUCN categorization as “Least Concern” and its classification into appendix II according to CITES. While individuals are potentially threatened by incidental fishing, no management units are currently used to conserve this species despite its high genetic differentiation.
... In Venezuela, the Atlantic spotted dolphin is widespread in both inshore and offshore waters (Romero et al., 2001). In Colombia this species is also found to be more common than pantropical spotted dolphins (Vidal, 1990;Pardo & Palacios, 2006). Atlantic spotted dolphins were recently observed in Aruba in the southern Caribbean (Luksenburg, 2013). ...
Technical Report
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This review brings our marine megafauna knowledge up to date and reports on species diversity and the occurrence of marine megafauna in Suriname waters. Emphasis is placed upon the most frequently recorded species and where possible, using systematic data. However, opportunistic (casual) records are also used when appropriate to help compile both distributional and density maps. Especially, when involving sightings of rare species this information is highly valuable in order to better understand the regional biodiversity.
... Las exploraciones sísmicas incluyen la producción de fuertes explosiones e intensos sonidos usando detonaciones en serie, los cuáles son fácilmente detectados a más de 10 km de distancia y tienen efectos potencialmente perjudiciales sobre los mamíferos marinos, entre los cuales están el estrés y la confusión, cambios en el comportamiento y en la vocalización, el movimiento de los animales de sus zonas de reproducción, daños auditivos y la muerte (Gordon et al., 2003). Adicionalmente, se registró en los años 90s un varamiento de dos delfines manchados del Atlántico en cercanías de Santa Marta relacionado con la contaminación sonora resultante de la pesca con dinamita (Pardo & Palacios, 2006). Aunque la práctica de pescar con dinamita y explosivos está prohibida en Colombia (Ley 13 de 1990), se continúa ejerciendo en diversas regiones de Colombia. ...
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Introducción: Los mamíferos marinos se ven afectados por diversas amenazas que deben identificarse para los esfuerzos de mitigación. Objetivo: Cuantificar visualmente las amenazas a los mamíferos marinos en Colombia e identificar acciones de mitigación. Métodos: Georreferenciamos las amenazas con base en la literatura, cubriendo 35 especies en el período 1991-2020, y las superpusimos en mapas de distribución de especies. Resultados: 22 especies presentaron al menos una amenaza. La captura incidental y las interacciones con los artes de pesca afectaron a 16 especies, seguidas de la captura directa (8 especies), el tráfico/tránsito de embarcaciones (6 especies) y la alteración de la física oceánica (6 especies). Las especies más afectadas, en cuanto a mayor diversidad de amenazas, son: ballena jorobada (Megaptera novaeangliae), manatí antillano del Caribe (Trichechus manatus), el tucuxi marino (Sotalia guianensis) y el delfín nariz de botella (Tursiops truncatus). Casi todo el territorio marino de Colombia presenta algún grado de riesgo para los mamíferos marinos. Las áreas de alto riesgo son Buenaventura, Guapi, Golfo de Cupica y Tumaco en el Pacífico; y Golfo de Urabá, Golfo de Darién, Golfo de Morrosquillo, frente a Barranquilla, Ciénaga Grande de Santa Marta y Golfo de Coquivacoa en el Caribe. Conclusión: Los mamíferos marinos en Colombia se encuentran actualmente en riesgo debido a varias amenazas, especialmente relacionadas con actividades de pesca, caza/captura y transporte marítimo, principalmente en las zonas costeras. Se necesitan acciones urgentes de evaluación y gestión en las diez áreas de alto riesgo identificadas en este estudio.
... Las exploraciones sísmicas incluyen la producción de fuertes explosiones e intensos sonidos usando detonaciones en serie, los cuáles son fácilmente detectados a más de 10 km de distancia y tienen efectos potencialmente perjudiciales sobre los mamíferos marinos, entre los cuales están el estrés y la confusión, cambios en el comportamiento y en la vocalización, el movimiento de los animales de sus zonas de reproducción, daños auditivos y la muerte (Gordon et al., 2003). Adicionalmente, se registró en los años 90s un varamiento de dos delfines manchados del Atlántico en cercanías de Santa Marta relacionado con la contaminación sonora resultante de la pesca con dinamita (Pardo & Palacios, 2006). Aunque la práctica de pescar con dinamita y explosivos está prohibida en Colombia (Ley 13 de 1990), se continúa ejerciendo en diversas regiones de Colombia. ...
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Los mamíferos marinos se ven afectados por diversas amenazas que deben identificarse para los esfuerzos de mitigación. Objetivo: Cuantificar visualmente las amenazas a los mamíferos marinos en Colombia e identificar acciones de mitigación. Métodos: Georreferenciamos las amenazas con base en la literatura, cubriendo 35 especies en el período 1991-2020, y las superpusimos en mapas de distribución de especies Resultados: 22 especies presentaron al menos una amenaza. La captura incidental y las interacciones con los artes de pesca afectaron a 16 especies, seguidas de la captura directa (8 especies), el tráfico/tránsito de embarcaciones (6 especies) y la alteración de la física oceánica (6 especies). Las especies más afectadas, en cuanto a mayor diversidad de amenazas, son: ballena jorobada (Megaptera novaeangliae), manatí antillano del Caribe (Trichechus manatus), el tucuxi marino (Sotalia guianensis) y el delfín nariz de botella (Tursiops truncatus). Casi todo el territorio marino de Colombia presenta algún grado de riesgo para los mamíferos marinos. Las áreas de alto riesgo son Buenaventura, Guapi, Golfo de Cupica y Tumaco en el Pacífico; y Golfo de Urabá, Golfo de Darién, Golfo de Morrosquillo, frente a Barranquilla, Ciénaga Grande de Santa Marta y Golfo de Coquivacoa en el Caribe. Conclusión: Los mamíferos marinos en Colombia se encuentran actualmente en riesgo debido a varias amenazas, especialmente relacionadas con actividades de pesca, caza/captura y transporte marítimo, principalmente en las zonas costeras. Se necesitan acciones urgentes de evaluación y gestión en las diez áreas de alto riesgo identificadas en este estudio. ________________________________________ Risk areas for marine mammals in Colombia Introduction: Marine mammals are affected by diverse threats that must be identified for mitigation efforts. Objective: To visually quantify threats to marine mammals in Colombia, and to identify mitigation actions. Methods: We georeferenced threats based on the literature, covering 35 species in the period 1991-2020, and superimposed them on species range maps. Results: 22 species had at least one threat. Bycatch and interactions with fishing gear affected 16 species, followed by direct capture (8 species), vessel traffic/transit (6 species) and alteration of ocean physics (6 species). The most affected species, in terms of the greatest diversity of threats, are: humpback whale (Megaptera novaeangliae), Caribbean West Indian manatee (Trichechus manatus), marine tucuxi (Sotalia guianensis) and bottlenose dolphin (Tursiops truncatus). Nearly all of Colombia's marine territory presents some degree of risk for marine mammals. High-risk areas are Buenaventura, Guapi, Cupica Gulf and Tumaco in the Pacific; and Urabá Gulf, Darién Gulf, Morrosquillo Gulf, off Barranquilla, Ciénaga Grande de Santa Marta and Coquivacoa Gulf in the Caribbean. Conclusion: Marine mammals in Colombia are currently at risk due to several threats, especially related to fishing , hunting/capture and shipping activities, mainly in coastal areas. Urgent evaluation and management actions are needed in the ten high-risk areas identified in this study.
... This was probably related to the low monitoring efforts carried out in these regions as this species presents a predominantly tropical distribution. Bryde's whales associate with regions of upwelling and consequently, with areas of high productivity (Gallardo et al., 1983;Kerosky et al., 2012;Pardo and Palacios, 2006;Tershy et al., 1990). Examples of upwelling regions are the Chilean coast (Gallardo et al., 1983), South Africa (Best, 2001), the tropical East of the Pacific Ocean (Palacios, 2003), the Santa Marta region of the Caribbean and the recess of Southern California (Kerosky et al., 2012), while productive regions include the Ballenas Channel in the Gulf of California (Tershy et al., 1990), in the continental shelf division and in the northeastern Gulf of Mexico (Davis et al., 1998). ...
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This study analysed 74 records of Bryde's whale strandings in jurisdictional Brazilian waters in order to further understanding of strandings in the region. Collation of records published in the media (newspapers, magazines, TV, online sources) and in peer-reviewed articles revealed 74 documented strandings between 1972 and 2015 along the coasts of Rio Grande do Sul, and Rio de Janeiro, Bahia and Maranhão states. Statistically significant differences were found between the frequencies of strandings in relation to Brazilian regions (χ² = 103.17), with the highest abundance found in the Southeast region (71.62%). Statistically significant differences were also observed between stranding frequency and sexual maturity (χ² = 12.31), with a higher abundance for sexually mature females (54.25%). No statistically significant difference between the stranding frequency in relation to seasonality (χ² = 2.8) was observed. No statistically significant difference between stranding frequency for males and females was found (χ² = 3.12). A simple linear regression showed an increasing trend of Bryde's whale strandings from the 1980s onwards, possibly due to population growth, increased monitoring throughout the Brazilian coast, and/or an increase in anthropogenic threats.
... Particularly in Colombia's Caribbean Sea, cetacean research has been limited, with most studies focusing on specific coastal mainland locations, including Santa Marta (Pardo and Palacios, 2006;Fraija et al., 2009;Pardo et al., 2009), Bay of Cispatá (García and Trujillo, 2004), Gulf of Morrosquillo (Palacios et al., 2013b), and La Guajira (Combatt and González, 2007;Palacios et al., 2012;Farías-Curtidor et al., 2017). To date, almost no research effort has been conducted in the remote oceanic region surrounding the Archipelago of San Andrés, Providencia and Santa Catalina (Pardo et al., 2009;Palacios et al., 2013b). ...
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Population structure studies play an increasingly integral role in conservation and management of marine mammal species. Genetic markers are commonly used; however, ecological markers (i.e. chemical compounds) are a fairly recent and useful tool to investigate ecological management units. The objective of this study is to investigate the population structure of the Atlantic spotted dolphin (Stenella frontalis) within its distribution in the Atlantic Ocean using data from stable isotopes of δ¹³C and δ¹⁵N and persistent organic pollutants as ecological markers. Based on previous studies that addressed distribution, morphometric analyses and molecular and ecological markers, we hypothesize that there are several ecological management units within the Atlantic Ocean. Our results confirmed population differentiation previously detected using genetic markers. Additionally, dolphins from the south-eastern coast of Brazil do not show complete ecological segregation from the Caribbean ones, while molecular analyses suggested genetic differentiation between the two regions. In the light of these results, we propose that at least two ecological management units should be considered, east and west of the Atlantic Ocean; however, the presence of one or two management units along the Atlantic coast of Central and South America needs further investigation.
Technical Report
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The document was authored by Courtney Vail and Monica Borobia as consultants to the SPAW-RAC in support of the SPAW Protocol of the Cartagena Convention and under the auspices of the Caribbean Environment Program, United Nations Environment Program. After more than a decade of Marine Mammal Action Plan (MMAP)-related programmatic work under the SPAW Protocol, this report compiles and reviews the status of major threats to marine mammals of the Wider Caribbean Region, and aims to assess progress by countries towards achieving implementation of the MMAP since its adoption by Parties in 2008 under the SPAW Protocol. A qualitative and quantitative assessment by country was conducted primarily to guide future action for continuing efforts towards the conservation and sound management of marine mammals in the Region. The assessments focused on 11 primary categories of issues or threats, including: fisheries interactions; habitat degradation and coastal development; pollution and marine mammal health; protected areas and other management regimes; research; whale watch and associated activities; marine mammal strandings; marine mammals in captivity; acoustic disturbance and underwater noise; vessel strikes; and climate change. A regional threats analysis and a summary review of the work of the SPAW Programme in support of MMAP implementation is also presented.
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Forty-one additional cetacean records are reported for the Leeward Dutch Antilles, expanding the list of documented records to 70 (53 sightings and 17 strandings). First records are given for the melon-head whale Peponocephala electra (Gray), such that now 13 species are confirmed for these islands. The most sighted whales are Bryde's whale and shortfin pilot whale, whereas the most sighted dolphins are spinner and bottlenose dolphins. Most cetacean movement is upstream and towards the east/southeast. Reported strandings have been on the rise, of which 47% involved beaked whales (goosebeak whale and Antillean beaked whale).
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As a contribution to the understanding of comparative social trends within the cetacean family Delphinidae, a 22-month study was conducted on the shortfinned pilot whale, Globicephala macrorhynchus, which has been suggested to have a unique social system in which males and females in the same group are related and mating occurs outside of the group. The individual identification of 495 pilot whales, analysed in daily group association patterns, allowed identification of 46 pods. They were classified as productive or non-productive based on the presence or absence of immature animals. Productive pods were a significantly larger, although 12% of them lacked adult males. Two classes of whales (residents and visitors) were defined by patterns of occurrence,suggesting differential patterns of habitat use. Resident pods occasionally travelled together (41% of all groups) and associations between age and sex classes showed that in mixed-pod groups, the highest ranked associations of the reproductive females were with males from other pods, while within pods, adult males and females associated less. During summer, the proposed peak conception period, pilot whale groups were significantly larger and contained individuals from a significantly greater number of pods. These findings support the hypothesis that males and females mate when associating with individuals from other pods. A comparative analysis of sexual dimorphism, brain size, and testes size, habitat, prey and group size within the 17 delphinid genera identified a correlation between sexual dimorphism and body size, but relative measures of brain size and testes size did not correlate with broad ecological or social classifications. However, a comparison of three delphinid societies identified two distinct male mating systems: males of the small, mono-morphic Tursiops truncatus live in age/sex segregated groups and mate with a number of discrete female communities. Males in the large sexually dimorphic Glob icephala spp. and Orcinus orca mate with associated female pods and yet remain with their female kin. This corresponds to the avunculate social system described in some human societies. It could evolve from a promiscuous mating system where there is little guarantee of paternity and where males that live with their kin increase their inclusive fitness.
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Between September 1999 and May 2000, seasonal changes of plankton communities were assessed in two contrasting tropical systems: Salamanca Gulf and Tayrona Natural National Park at the coastal, south-central Colombian Caribbean Sea. We measured hydrographic characteristics of the water column, size fractionated phytoplankton biomass, protein/carbohydrate ratios (P/C) of the particulate organic material, phytoplankton (>55 µm), and mesozooplankton composition and density. Between zones no change was detected in water column characteristics, but there were changes among seasons (rainy and dry) in both areas. High chlorophyll a concentrations in the phytoplankton community prevailed during both seasons. The phytoplankton taxonomic composition, mesozooplankton assemblages, as well as P/C ratio, differed between seasons. This variability was derived from differences in fresh and brackish water input to the continental shelf (rainy season) and potentially upwelling (dry season). Albeit differences in the intensity of the oceanographic processes, Salamanca Gulf and Tayrona Natural National Park varied similarly by climatic season. Our results showed strong seasonal differences in the plankton community, contrasting with the general perspective of tropical Caribbean systems where plankton communities are usually considered of low variability and concentration all year long.
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The marine form of the South American dolphin Sotalia fluviatilis has an extensive and possibly continuous distribution, from the Florianópolis region, Brazil (27°35′S, 48°34′W), north to Panama (~9°22′N, 79°54′W). The high number of records from 25–20°S is due to the presence of many observers in those latitudes. The freshwater form of this species inhabits the Amazon and Orinoco drainages. It is commonly seen in the Amazon, and has been found as far inland as southern Peru. The southern limit of the range of the marine form of Sotalia is associated with the confluence zone of the Brazil and Falkland currents, suggesting that low sea-surface temperature is a limiting factor, whereas in fresh water the distribution of Amazonian Sotalia seems more closely related to the movements and concentrated occurrence of prey.
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Durante la misión oceanográfica “CARACOLANTE” realizada en noviembre de 1981 en la plataforma continental colombiana del Caribe, medidas rutinarias de temperatura y salinidad fueron ejecutadas. Los resultados permitieron suponer la existencia de “Células ciclónicas” de corriente (hasta la fecha limitada a dos, debido a la falta de datos suficientes). El origen de estas células puede ser el resultado del efecto conjunto de la corriente del Caribe y de la contra-corriente Litoral, hipótesis que se tratará de verificar en crucero posterior, con medidas de corriente y boyas de deriva. Además, un reconocimiento preliminar en la desembocadura del delta del Magdalena, indica igualmente el efecto de esta contra-corriente en la difusión de las aguas fluviales y para la dispersión en el mar de los efluentes en suspensión.
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A zoogeographical analysis of cetaceans in the waters of Puerto Rico, US Virgin Islands, and British Virgin Islands was conducted to document the different species found, and to relate their occurrences to patterns of ocean floor topography. A total of 2,016 sighting records was entered into a specially formatted database system, and analyzed for distributional and temporal patterns. Species included 13 odontocetes and four mysticetes. The hypothesis that the spatial distribution of cetaceans is highly correlated to the area's bathymetric relief, whether high or low, was generally supported. Through the use of a relative slope index measure, each sighting was characterized by depth classes (shelf, shelf edge, or offshore), and by sea floor relief.
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A bstract The taxonomy of the spotted dolphins has been confused. Two apparent species exist, one endemic to the Atlantic and the other pantropical. They have sharply different color patterns and non‐overlapping vertebral counts. However, the holotype specimens for most of the names that have been applied to the spotted dolphins (including S. attenuata, S. frontalis, S. plagiodon and others) are skulls only, with no information on coloration or number of vertebrae. The two species overlap in all skull characters; geographical variation in both is pronounced. We used a discriminant analysis based on tooth counts and three skull measurements (standardized to skull width) to identify the type specimens to the two species. We used other criteria for assignment of nominal species for which holotype specimens do not exist. We propose that Stenella frontalis (G. Cuv., 1829) be used for the Atlantic endemic species and Stenella attenuata (Gray, 1846) for the pantropical species and here redescribe the species. Proposed common names are Atlantic spotted dolphin and pantropical spotted dolphin. S. frontalis now includes Delphinus froenatus F. Cuv., 1829, D. doris Gray, 1846 and D. plagiodon Cope, 1866. S. attenuata (a nomen conservandum) includes D. velox G. Cuv., 1829, D. pseudodelphis Wiegmann, ≤ 1840, D. brevimanus Wagner, 1846, D. microbrachium Gray, 1850, D. albirostratus Peale, 1848, Steno capensis Gray, 1865, Clymene punctatus Gray, 1866, Steno consimilis Malm, 1871 and Prodelphinus graffmani Lönnberg, 1934. Unidentifiable to either of the two valid species are D. dubius G. Cuv., 1812, D. pernettensis de Blainville, 1817 (suppressed), D. malayanus Lesson, 1826 and D. Rappii Reichenbach, 1845; these must remain incertae sedis.