Dusky dolphin<i>(Lagenorhynchus obscurus)</i>feeding tactics and multi‐species associations

Vaughn, Robin L.; Shelton, Deborah E.; Timm, Lori L.; Watson, Leslie A.; Würsig, Bernd

doi:10.1080/00288330709509929

Cited by 46 publications

(50 citation statements)

References 19 publications

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“…Across taxa, multi-specific interactions between marine mammals, fish and birds are also commonly observed (e.g. Pitman & Ballance 1992, Bearzi 2006, Vaughn et al 2007, Haynes et al 2011, Scott et al 2012, and while these interactions are even less well understood, they may influence the spatial distribution of a species through processes such as mutualism, commensalism or competition. For example, based on an observed negative relationship between the abundance of sei whales Bal-aenoptera borealis and the occurrence of DVM in the copepod Calanus finmarchicus, Baumgartner et al (2011) speculated that the occurrence of zooplanktivorous fish influenced the distribution of sei whales by inducing DVM behaviour in their common copepod prey.…”

Section: Intra-or Interspecific Interactionsmentioning

confidence: 99%

Beyond correlation: integrating environmentally and behaviourally mediated processes in models of marine mammal distributions

Palacios¹,

Baumgartner²,

Laidre³

et al. 2013

Endang. Species. Res.

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Marine species distribution modeling has seen explosive growth in recent years, and the Endangered Species Research Theme Section entitled 'Beyond marine mammal habitat modeling: applications for ecology and conservation' demonstrates that the field of marine mammalogy has been no exception. For the past decade, marine mammal ecologists have been developing habitat models with increasing proficiency and sophistication. However, these efforts have largely focused on correlative analyses of observed species−environment associations, which often have low explanatory power due to the absence of critical, but unaccounted for processes that are important drivers of animal distributions. Here we provide an overview of these processes, advocate for directed studies (e.g. tagging, prey sampling, focal follows, physiological assessment) to address how the processes influence species' distributions, and challenge the modeling community to incorporate these results into their efforts. We also identify a progression of modeling stages from correlative to confirmatory to mechanistic that should lead us to formulate increasingly robust and accurate predictions of species distributions rooted in greater ecological understanding. Given the on-going risks to marine mammals from human activities and climate change, such models are needed for conservation and management now more than ever. FREE REE ACCESS CCESS Contribution to the Theme Section 'Beyond marine mammal habitat modeling'Endang Species Res 22: 191-203, 2013 ecology and conservation' clearly demonstrate that the marine mammal research community has embraced these tools, and is applying them with increasing proficiency and sophistication (Gregr et al. 2013, this Theme Section).Marine mammal habitat models typically predict the spatial distribution or abundance of a species based on correlations between animal observations and attributes of the physical marine environment (e.g. seafloor terrain, sea surface temperature, proximity to the ice edge) or proxies of dynamic oceanographic processes that may directly or indirectly aggregate prey (Redfern et al. 2006). This approach often makes 2 implicit assumptions with regard to the environmental variables: (1) they adequately capture the underlying environmental gradients to which a species responds, and (2) they reasonably represent conditions that lead to enhanced feeding opportunities. These assumptions, and the focus on foraging success, reflect the limits of our understanding of how marine mammals interact with their environment as well as our ability to directly measure the prey field at scales relevant to a foraging predator.The correlative approach has generated considerable insight into the distribution of marine mammal species and their potential foraging areas. However, our models continue to capture only a small portion of the observed variability in species' occurrence or abundance. For example, the deviance explained (a measure of model fit) by models published in this Theme Section was generally be...

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Section: Intra-or Interspecific Interactionsmentioning

confidence: 99%

Beyond correlation: integrating environmentally and behaviourally mediated processes in models of marine mammal distributions

Palacios¹,

Baumgartner²,

Laidre³

et al. 2013

Endang. Species. Res.

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“…These associations are widespread, occurring among several genera of both groups (e.g. Evans, 1982;Ridoux, 1987;Au, 1991;Bräger, 1998;Vaughn et al, 2007). Most associations, however, are probably opportunistic or incidental, as a result of concentration of shared prey.…”

Section: Introductionmentioning

confidence: 99%

“…Würsig and Würsig, 1979;Würsig and Würsig, 1980;Evans, 1982;Au and Pitman, 1986;Shane, 1990;Neumann and Orams, 2003;Siciliano et al, 2004;Vaughn et al, 2007). In Brazil, most reports have involved associations between Guiana dolphins, Sotalia guianensis (Van Bénèden, 1864), and seabirds (e.g.…”

Section: Introductionmentioning

confidence: 99%

Feeding associations between Guiana dolphins, Sotalia guianensis (Van Bénèden, 1864) and seabirds in the Lagamar estuary, Brazil

et al. 2010

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The main objective of the present study was to describe the characteristics regarding interactions between Guiana dolphins, Sotalia guianensis and seabirds in feeding associations in two distinct areas of the Lagamar estuary, Brazil. Boat-based surveys directed towards photo-identification studies of S. guianensis were conducted in the Cananéia Estuary (CE) (25° 01' S and 47° 55' W) from July 2004 to March 2008, as well as in the Paranaguá Estuarine Complex (PEC) (25° 24' S and 48° 24' W) from April 2006 to February 2008. On all occasions when seabirds were observed engaging in multi-species feeding associations with S. guianensis, data on species involved and their numbers were gathered. From 435 observed groups of S. guianensis in the CE, 38 (8.7%) involved interactions with seabirds. In the PEC, from the 286 observed groups, 32 (11.2%) involved the mentioned interactions. The following seabirds were observed in feeding associations with S. guianensis: Fregata magnificens, Sula leucogaster, Phalacrocorax brasilianus, and Sterna sp. In the CE, S. leucogaster was more commonly observed in feeding associations with Guiana dolphins (χ² = 22.84; d.f. = 3, p < 0.05), while in the PEC no differences were reported when comparing seabird species (χ² = 5.78; d.f.=3, p = 0.1223). In the CE, feeding associations were significantly more frequent in inner waters (subset A0; χ² = 9.52; d.f. = 2, p < 0.05), and in winter (χ² = 12.46; d.f. = 1, p < 0.05). Within these events, 44.7% of the association groups were composed by more than one seabird species. Seasonality in feeding associations was also observed in the PEC (χ² = 4.76; d.f. = 1, p < 0.05), with same patterns observed in the CE. Interactions were more frequent in inner waters of the Laranjeiras bay, PEC (χ² = 11.65; d.f. = 2, p < 0.05). Within these events, 74.2% of the association groups were composed by more than one seabird species. Water transparency, prey and seabird abundance and distribution, cetacean group size, and the life cycle of prey and seabirds are listed as the main factors addressing multi-species feeding associations in the Lagamar estuary.Keywords: Cetacea, feeding associations, Sotalia guianensis, seabirds, multi-species interactions. Associações de alimentação entre o boto-cinza (Sotalia guianensis) (Van Bénèden, 1864) e aves marinhas no estuário do Lagamar, BrasilResumo O objetivo principal do presente estudo foi de descrever as características a respeito das associações de alimentação entre o boto-cinza, Sotalia guianensis, e aves marinhas em duas áreas distintas do estuário do Lagamar, Brasil. Investigações efetuadas a partir de embarcação e direcionadas a estudos de foto-identificação de S. guianensis foram conduzidas (χ² = 5,78; g.l. = 3, p = 0,1223). No EC, associações de alimentação foram significativamente mais freqüentes em águas internas (χ² = 9,52; g.l. = 2, p < 0,05) e no inverno Santos, MCO. et al.

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“…Here, dolphins feed during the day on schooling fish such as pilchard (Sardinops sagax), sprat (Sprattus spp.) and mullet (Aldrichetta forsteri) (Duffy & Brown 1994;McFadden 2003;Vaughn et al 2007). Little is known about seasonal prey density, distribution and availability.…”

Section: Introductionmentioning

confidence: 99%

“…A subset of data collected as part of a larger group of studies (Markowitz et al , 2010Vaughn et al 2007Vaughn et al , 2008Vaughn et al , 2010Pearson 2009) was examined to assess changes in dusky dolphin encounter rates in Admiralty Bay during 2001Á2006. We investigated oceanographic and climatic factors that could affect inter-annual dolphin encounter rate patterns.…”

Section: Introductionmentioning

confidence: 99%

Using climate downscaling to hypothesise impacts on apex predator marine ecosystem dynamics

Srinivasan

Pearson

Vaughn-Hirshorn

et al. 2012

New Zealand Journal of Marine and Freshwater Research

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Climate downscaling studies help to connect global predictions and projections with regional dynamics and generate a better understanding of past and future conditions. Adding ecological variables and trophic relationships into the climate equation is challenging since there are few clear connections. The present study is an exploratory data analysis to explain dusky dolphin (Lagenorhynchus obscurus) encounter rate patterns in Admiralty Bay, New Zealand. During 2001Á2006, dolphin encounter rate in winter decreased from 6 to 0.8 groups/h and the proportion of dolphin groups observed feeding decreased from 80% to 38% in Inner Admiralty Bay. These trends generally corresponded to cooler and moderate El Nin˜o Southern Oscillation years, lower sea surface height, southwesterly winds, increased surface mixing and decreased sea surface salinity. To fully grasp the significance of these relationships and potential impact(s) on dolphin population trends, directed long-term studies that synthesise dolphin, prey, water quality, anthropogenic pressures and climatic information into regional climate-ecosystem models are needed.

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Dusky dolphin(Lagenorhynchus obscurus)feeding tactics and multi‐species associations

Cited by 46 publications

References 19 publications

Beyond correlation: integrating environmentally and behaviourally mediated processes in models of marine mammal distributions

Beyond correlation: integrating environmentally and behaviourally mediated processes in models of marine mammal distributions

Feeding associations between Guiana dolphins, Sotalia guianensis (Van Bénèden, 1864) and seabirds in the Lagamar estuary, Brazil

Using climate downscaling to hypothesise impacts on apex predator marine ecosystem dynamics

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