Coordinated feeding tactics of the Guiana dolphin, Sotalia guianensis (Cetacea: Delphinidae), in Ilha Grande Bay, Rio de Janeiro, Brazil

Tardin, Rodrigo H.; Espécie, Mariana A.; Nery, Mariana F.; D'Azeredo, Felipe; Simão, Sheila M.

doi:10.1590/s1984-46702011000300002

Cited by 16 publications

(13 citation statements)

References 9 publications

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“…During the second category of interactions, on one occasion (February, 2005) 15-20 S. guianensis were foraging <1 km from the mouth of the das Peças River, when a M. birostris (c. 4 m W D ) breached <300 m to the north. All S. guianensis immediately moved to the breached area and executed various foraging behaviours, including actively surfacing (Tardin et al, 2011). Similar events within the second category of interactions were more recently observed (January to March of 2012 and 2014) by other local researchers.…”

supporting

confidence: 71%

“…4 m disc width; W D ) breached once or twice adjacent to the school and landed on its dorsal surface directly over the school [see Medeiros et al ., for a description of breaching]. Immediately following the final breach, between six and 20 S. guianensis (involving different groups, identified by dorsal‐fin marks) surfaced at the school and executed characteristic foraging behaviours, including deep diving, crossed fishing activities and circle formation (Monteiro‐Filho, ; Tardin et al ., ). Once S. guianensis arrived, there were no subsequent breaches by M. birostris , although their maintained presence was confirmed during two of the six interactions by pectoral fins breaking the water surface.…”

mentioning

confidence: 97%

“…4 m W D ) breached <300 m to the north. All S. guianensis immediately moved to the breached area and executed various foraging behaviours, including actively surfacing (Tardin et al ., ). Similar events within the second category of interactions were more recently observed (January to March of 2012 and 2014) by other local researchers.…”

mentioning

confidence: 97%

“…This study contributes towards addressing the shortfall in understanding delphinid-elasmobranch foraging interactions by describing observations made in the PEC during several studies investigating the ecology of S. guianensis between 2003 and 2009. The observations encompassed variable spatio-temporal effort, but were done following a combination of focal-animal and continuous recording sample methods from fixed points (Lehner, 1997) -Filho, 1995;Tardin et al, 2011). Once S. guianensis arrived, there were no subsequent breaches by M. birostris, although their maintained presence was confirmed during two of the six interactions by pectoral fins breaking the water surface.…”

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confidence: 99%

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Interactions between Manta birostris and Sotalia guianensis in a World Heritage listed Brazilian estuary

Domit

Broadhurst

Bornatowski

2017

Journal of Fish Biology

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During 1442 h of visual observations over 7 years throughout the World Heritage listed Paranaguá estuarine complex, Brazil, seven occurrences of interactions were observed at a single location involving breaching Manta birostris displacing schools of teleosts, which were subsequently preyed upon by Sotalia guianensis. Although the interactions were not definitively categorized as being amensal, commensal or mutual, their restriction to isolated space (adjacent to a protected area) and time (summer) supports previous assertions the area is important to regional productivity and the continuation of protected-area status.

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supporting

confidence: 71%

mentioning

confidence: 97%

mentioning

confidence: 97%

mentioning

confidence: 99%

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Interactions between Manta birostris and Sotalia guianensis in a World Heritage listed Brazilian estuary

Domit

Broadhurst

Bornatowski

2017

Journal of Fish Biology

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“…Ilha Grande Bay population is one of the largest populations, within the whole extent of the species, of Guiana dolphins, estimated at 760 individuals (Espécie, ) and with >65% of individuals considered as resident. Dolphins use the bay mainly for feeding and caring for young, 94% of the groups found in this area included immature individuals (Tardin, Galvão, Espécie, & Simão, ). Earlier studies conducted in Ilha Grande Bay indicated that dolphins used shallow waters (Lodi, ).…”

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confidence: 99%

Modelling habitat use by the Guiana dolphin, Sotalia guianensis, in south‐eastern Brazil: Effects of environmental and anthropogenic variables, and the adequacy of current management measures

Tardin

Maciel

Espécie

et al. 2020

Aquatic Conservation

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1. Species distribution modelling has been used to identify critical habitats for the delimitation of Marine Protected Areas. Although Marine Protected Areas may often overlap with the distribution of key marine species, illegal human activities often continue within these areas, causing negative impacts on the local biodiversity. 2. A generalized linear model with spatial eigenvector mapping was used to investigate, for the first time, the influence of environmental variables and anthropic activities on the number of Guiana dolphin, Sotalia guianensis sightings/grid, and to determine whether a Marine Reserve, in south-eastern Brazil, is adequate for the protection of the local population. Data were collected between May 2007 and October 2013 onboard a 7.5-m vessel with an inboard engine.3. The models for the different periods (annual, dry, and rainy seasons) all indicated that depth, the distance to seafood farms and fishing grounds, and mean sea surface temperatures influenced the distribution of the dolphins within the study area. The annual and seasonal models predicted that the dolphins prefer a continuous area between Cedro and Pico Islands, a large area that lies outside the limits of the Marine Reserve. 4. Although the habitat of Ilha Grande bay is still much less degraded than that inhabited by other nearby Guiana dolphin populations, the results of the present study indicate that anthropic activities in this area influence habitat use by the dolphins. Less than 30% of the area used by the dolphins is protected by the Tamoios Ecological Station (ESEC Tamoios). 5. Sotalia guianensis is classified as 'Vulnerable' in Brazil, although the marine reserve (ESEC Tamoios) does not protect the core area used by the local dolphin population. The results of the present study provide specific locations for the creation of a new multiple-use MPA, as suggested by the Brazilian National Action Plan for the Conservation of Small Cetaceans, or the inclusion of a special management programme for the area between Cedro and Pico islands to better protect the dolphins in the ESEC Tamoios buffer zone. The continuation of surveys to better

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20 years of research on the Guiana dolphin population of Sepetiba Bay, southeastern Brazil: What has changed?

Maciel,

Maricato,

Marqui

et al. 2023

Aquatic Conservation

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Despite the importance of coastal habitats for the provision of many ecosystem services, these areas are currently among the most impacted by human activities. Impacts on coastal ecosystems may affect many key species, such as the Guiana dolphin, which inhabits Sepetiba Bay in south‐eastern Brazil, a highly degraded environment owing to a human‐induced rapid environmental change. In this context, this study investigates the potential changes in the local Guiana dolphin behaviour, group structure, bioacoustics, site fidelity and habitat use over the past 20 years. For this, a historical database (1998–2007) was compared with current data on the local dolphin population (2017–2019). Between 2017 and 2019, the Guiana dolphins form significantly smaller groups (W = 3262.5, P > 0.001), spend more time foraging (61 vs. 10% in the past), emit whistles at a considerably lower rate (decreasing by 85.2%), have reduced site fidelity and now use a larger area. As Sepetiba Bay has been severely impacted by human activities in the recent past, with profound consequences for much of its biodiversity, the observed changes in dolphin behaviour are probably a consequence of habitat degradation and, in particular, of reduced prey availability. These findings have important implications for the management and conservation of the Guiana dolphin population of Sepetiba Bay. To break this human‐induced rapid environmental change, it will be essential to minimize the spatio‐temporal overlap of anthropogenic impacts, to avoid cumulative impacts. To mitigate anthropogenic impacts on the Guiana dolphins of Sepetiba Bay, it will be important to direct the following actions: (i) the regulation and control of anthropogenic noise; (ii) reduction and control of the release of chemical contaminants and organic effluents; (iii) more effective controls on vessel traffic within the areas used preferentially by the Guiana dolphin; and (iv) the implementation of measures to avoid overfishing and bycatch.

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Coordinated feeding tactics of the Guiana dolphin, Sotalia guianensis (Cetacea: Delphinidae), in Ilha Grande Bay, Rio de Janeiro, Brazil

Cited by 16 publications

References 9 publications

Interactions between Manta birostris and Sotalia guianensis in a World Heritage listed Brazilian estuary

Interactions between Manta birostris and Sotalia guianensis in a World Heritage listed Brazilian estuary

Modelling habitat use by the Guiana dolphin, Sotalia guianensis, in south‐eastern Brazil: Effects of environmental and anthropogenic variables, and the adequacy of current management measures

20 years of research on the Guiana dolphin population of Sepetiba Bay, southeastern Brazil: What has changed?

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