Tidal influences on the habitat use of Indo-Pacific humpback dolphins in an estuary

Lin, Tzu‐Hao; Akamatsu, Tomonari; Chou, Lien‐Siang

doi:10.1007/s00227-013-2187-7

Cited by 45 publications

(51 citation statements)

References 32 publications

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“…Using methods of acoustic detection, Lin et al (2013) found that S. chinensis are more often found at the entrance of the Xin Huwei estuary in Taiwan at high tide, while in Lundy Island, 19 km from the coast of England, most acoustic detection of P. phocoena occurred during the ebb tide (Squires et al 2014). In southwest Britain, the foraging behaviour of P. phocoena is more common at the peak of high tide (Goodwin 2008), while in a nearby shallow coastal area of Cardigan Bay, United Kingdom, foraging is related to the flood period (De Boer et al 2014).…”

Section: Discussionmentioning

confidence: 99%

“…Parsons 1998, Lin et al 2013). Thus, it is possible that the characteristics of each habitat determine how the tidal cycles influence the environment and, consequently, how dolphins use the habitat (Lin et al 2013).…”

Section: Discussionmentioning

confidence: 99%

“…Several fish species become more active at night, and dolphins may use the habitat differently over nictemeral cycles. Acoustic monitoring is the only method allowing such observations, as it is not possible to visually monitor the dolphins overnight (Lin et al 2013).…”

Section: Discussionmentioning

confidence: 99%

“…These tidal migrations involve the movement of large numbers of species between locations synchronously with the tidal cycle (Gibson 2003). Top predators should be able to take advantage of these temporal changes in the aquatic environment to optimize the capture of prey (Lin et al 2013).…”

Section: Introductionmentioning

confidence: 99%

“…Shane 1990, Bordino 2002), but few studies have specifically aimed to describe these effects in detail (e.g. Mendes et al 2002, Fury and Harrison 2011, Lin et al 2013. Hypotheses from optimal foraging theory (Perry and Pianka 1997) suggest that dolphins have lower spatial requirements in terms of area used when resource availability is higher.…”

Section: Introductionmentioning

confidence: 99%

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Tidal and seasonal influences in dolphin habitat use in a southern Brazilian estuary

2017

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Summary:In this study we describe how franciscana and Guiana dolphin habitat use is influenced by tidal cycles and seasonality in Babitonga Bay. The franciscanas use a greater area in winter and a smaller area in summer, but the extent of the area used did not vary with the tide. Guiana dolphins did not change the extent of the area used within seasons or tides. Franciscanas remained closer to the mouth of the bay and the islands during ebb tide, moving to the inner bay areas and closer to the mainland coast during flood tide. Guiana dolphin used areas closer to the mainland coast during the flood tide. Guiana dolphin patterns of movement do not seem to be related to the tidal current. Franciscanas used sandier areas while Guiana dolphins preferred muddy areas, with some seasonal variation. We suggest that these dolphins modify their distributions based on habitat accessibility and prey availability. This study enhances our knowledge of critical habitat characteristics for franciscana and Guiana dolphins, and these factors should be considered when planning local human activities targeting species conservation.Keywords: tide cycles; survey method; franciscana dolphin; Guiana dolphin; critical habitat; Babitonga Bay; SW Atlantic Ocean. Influencia de las mareas y las estaciones en el uso de hábitat de delfines en un estuario del sur de BrasilResumen: En este estudio describimos como el uso del hábitat del delfín franciscana y delfín costero es influenciado por los ciclos de mareas y las estaciones en la bahía Babitonga. Las franciscanas utilizan áreas mayores en invierno y menores en verano, pero el tamaño del área utilizada no varió con las mareas. El área de uso del delfín costero no varió entre estaciones ni con las mareas. Las franciscanas permanecieron más próximas a la boca de la bahía e islas durante la marea baja, moviéndose hacia áreas más internas cercanas al margen del continente durante la marea alta. Del mismo modo, el delfín costero utilizó áreas cercanas al margen del continente durante la marea alta. Los patrones de movimiento del delfín costero no presentaron relación con las corrientes de marea. Las franciscanas utilizaron áreas con más arena mientras que los delfines costeros prefirieron áreas lodosas; esta preferencia varió estacionalmente para ambas especies. Sugerimos que estos delfines modifican su distribución en base a la accesibilidad del hábitat y la disponibilidad de presas. Este estudio aumenta nuestro conocimiento sobre las características del hábitat crítico para la franciscana y el delfín costero, y estos factores deben ser considerados en la planificación de las actividades humanas locales orientadas a la conservación de estas especies.Palabras clave: ciclos de mareas; método de barrido; delfín franciscana; delfín costero; hábitat crítico; bahía Babitonga; Océano Atlántico SO.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Tidal and seasonal influences in dolphin habitat use in a southern Brazilian estuary

2017

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Distribution and habitat characteristics of three sympatric cetacean species in the coastal waters of Matang, Perak, Peninsular Malaysia

Kuit

Ponnampalam²,

Ng³

et al. 2019

Aquatic Conservation

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Coastal cetaceans in Southeast Asia are poorly studied and are particularly vulnerable to anthropogenic threats, especially in intensive fishing grounds. To investigate the distribution and habitat characteristics of cetaceans in the productive coastal waters of Matang, Perak, Malaysia, boat‐based line transect surveys were conducted between 2013 and 2016. The Irrawaddy dolphin (Orcaella brevirostris) was most frequently encountered at 3.87 sightings per 100 km, followed by the Indo‐Pacific finless porpoise (Neophocaena phocaenoides) at 1.72 sightings per 100 km, and the Indo‐Pacific humpback dolphin (Sousa chinensis) at 0.66 sightings per 100 km. The mean group size was largest for humpback dolphins (8.4 individuals), followed by Irrawaddy dolphins (6.4 individuals), and finless porpoises (2.8 individuals). Humpback dolphins exhibited a clustered distribution concentrated mainly in shallow estuarine waters (<10 m deep and <5 km from river mouths), whereas Irrawaddy dolphins were more widely distributed in farther coastal waters (<15 m deep and <15 km from river mouths), and finless porpoises were mostly found farthest from the shore in coastal waters (10–25 m deep and >15 km from river mouths). The spatial distribution of the three cetaceans overlapped minimally, and this is likely to reflect the distribution of preferred prey resources, species interactions, and their differential responses to anthropogenic activities and species dominance. The results from our study serve as baseline information for future research, conservation, and habitat management of these vulnerable and endangered coastal cetaceans. Conservation actions are recommended for the Matang area.

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Food risk trade‐off in the Indo‐Pacific humpback dolphin: An exploratory case study

Lin

Caruso

Liu

et al. 2020

Aquatic Conservation

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1. Based on optimal foraging theory, animals are expected to maximize foraging benefits whilst minimizing risks. Despite risking being subjected to anthropogenic impacts such as water contamination, marine traffic, and underwater noise, estuaries have been identified as the preferred habitat of the Indo-Pacific humpback dolphin (Sousa chinensis, IPHD). However, it remains unclear why this vulnerable species favours such risky habitats. 2.Here, an exploratory case study in Zhanjiang estuary, China, was conducted to test the hypothesis that IPHDs select estuarine habitats as a trade-off that maximizes foraging opportunities whilst minimizing the risk of mortality.3. The results showed that IPHDs accept greater mortality risks for higher food rewards but select habitats with lower risks when food rewards are similar between two locations. 4. Although this type of information is important for underpinning models for individual dolphins, its principal role is to show environmental protection agencies why IPHDs favour estuaries despite the increased mortality risks. 5.Habitat conservation plans should carefully consider prey stocks, possibly through the presence of marine protected areas near estuaries, as local overfishing may lead vulnerable cetacean populations to take greater risks. K E Y W O R D S coastal waters, endangered species, estuary, human disturbance, marine mammals, marine traffic, over-fishing

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Tidal influences on the habitat use of Indo-Pacific humpback dolphins in an estuary

Cited by 45 publications

References 32 publications

Tidal and seasonal influences in dolphin habitat use in a southern Brazilian estuary

Tidal and seasonal influences in dolphin habitat use in a southern Brazilian estuary

Distribution and habitat characteristics of three sympatric cetacean species in the coastal waters of Matang, Perak, Peninsular Malaysia

Food risk trade‐off in the Indo‐Pacific humpback dolphin: An exploratory case study

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