Population variance in prey, diets and their macronutrient composition in an endangered marine predator, the Franciscana dolphin

Denuncio, Pablo; Viola, M. Natalia Paso; Machovsky‐Capuska, Gabriel E.; Raubenheimer, David; Blasina, Gabriela; Machado, Rodrigo; Polizzi, P.; Gerpe, Marcela Silvia; Cappozzo, Humberto Luis; Rodríguez, Diego H.

doi:10.1016/j.seares.2017.05.008

Cited by 27 publications

(12 citation statements)

References 53 publications

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“…The P. harroweri southern distribution limit is around the coast of Rio Grande do Sul, about 30°S (Di Dario et al ., 2017). This species distribution was reflected in the absence of P. harroweri among the main prey items in FMAs III and IV (Paso-Viola et al ., 2014; Denuncio et al ., 2017; Franco-Trecu et al ., 2017; Tellechea et al ., 2017). Pellona harroweri is pelagic, contrasting with the demersal habits of I. parvipinnis and Stellifer sp.…”

Section: Discussionmentioning

confidence: 99%

“…The average size of consumed fish was 5.25 cm (see Table 2), smaller than the average length (up to 11 cm) observed in other FMAs (e.g. Di Beneditto & Ramos, 2001; Rodriguez et al ., 2002; Bittar & Di Beneditto, 2009; Cremer et al ., 2012; Denuncio et al ., 2017; Tellechea et al ., 2017). The observed small prey sizes are often associated with younger development stages of the prey species (Cousseau & Perrota, 2000; Fischer et al ., 2011).…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, juvenile and adult individuals may also be important for the feeding habits of franciscana dolphins, especially due to their contribution to the ingested biomass. The consumed cephalopods were generally larger than fish (mean = 8.6 cm) as observed in previous studies (Rodriguez et al ., 2002; Paso-Viola et al ., 2014; Denuncio et al ., 2017).…”

Section: Discussionmentioning

confidence: 99%

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Feeding habits of the franciscana dolphin (Pontoporia blainvillei) in south-eastern Brazil

et al. 2020

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This study evaluated the feeding habits of the franciscana dolphin (Pontoporia blainvillei) in south-eastern Brazil. Stomach contents were collected from a total of 145 dead specimens found incidentally caught by fishing vessels or stranded between 2005 and 2015. Fish otoliths, cephalopod beaks and whole non-digested prey were used for prey species identification. A total of 9337 prey items were identified, including 26 species of teleost fishes and three species of cephalopods. The most important prey families were Sciaenidae among fish and Loliginidae among cephalopods. Franciscana dolphins tended to feed on small fish (mean = 5.25 cm) and cephalopods (mean = 8.57 cm). The index of relative importance (IRI) showed that Pellona harroweri and Doryteuthis plei were the most important prey for both males and females. The PERMANOVA test confirmed that there is no significant difference between the feeding habits of different sexes, but detected a significant difference among seasons. Overall, our results show that franciscana dolphins are predominantly ichthyophagous and non-selective in relation to the type of prey, feeding on pelagic, demersal and pelagic-demersal prey.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Feeding habits of the franciscana dolphin (Pontoporia blainvillei) in south-eastern Brazil

et al. 2020

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“…An important feature of the BMC is that its position oscillates seasonally and geographically along the study area, affecting the north and south coastal regions differently, which in turn influences the distribution and abundance of many franciscana dolphin prey species (Haimovici, 1997 a , 1997 b ). Consequently, the most important prey of franciscana dolphin differed between the northern and southern regions of the study area, which was also reported in other studies comparing neighbourhood sites and franciscana sub-populations distributed in marine and estuarine areas in Argentina (Rodrígues et al ., 2002; Denuncio et al ., 2017). Despite the fact that these are adjacent areas and some diet differences also include cephalopod beak presence and absence (and these structures can remain months in the stomach), it seems that the animals are not swimming to distant areas.…”

Section: Discussionmentioning

confidence: 99%

Intrapopulation variation in the diet of franciscana dolphin (Pontoporia blainvillei) off southern Brazil

Bassoi

Secchi

Danilewicz³

et al. 2021

J. Mar. Biol. Ass.

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The franciscana dolphin (Pontoporia blainvillei) is a coastal dolphin endemic to the western South Atlantic Ocean. The dolphin is listed as vulnerable in the IUCN Red List, with incidental catches in gillnet fisheries the greatest conservation concern for this species. Insights into the feeding habits of this dolphin are essential to understand its distribution, movements and use of habitat, which are fundamental for effective management of the species. The feeding habits of franciscana dolphins were investigated from analyses of stomach contents of animals incidentally caught by two fishing operations from southern and northern regions of the southern Brazilian coast. In this study we investigate the existence of intrapopulation (sexual maturity and sex-related) variation in the diet of the franciscana dolphin, evaluating the spatial (northern and southern geographic areas) and seasonal influences. The analyses were based on Linear and Generalized Linear Models (LM and GLM). The majority of identified prey species were bottom-dwelling teleosts and the squid Doryteuthis sanpaulensis. The most important prey differed spatially and seasonally between northern and southern regions of the study area, and our results revealed significant differences between sexes and sexual maturity stages, mainly related to prey species sizes. This variation might indicate differences in prey selection, availability or habitat use patterns among these groups. In any case, these dietary differences are likely to minimize intraspecific competition for food resources, and/or indicate spatio-temporal variation in prey availability.

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“…Marine apex predators are long-lived species that forage in complex three-dimensional environments and therefore represent an ideal group to better understand dietary generalism in the wild (Denuncio et al, 2017;Machovsky-Capuska, Priddel et al, 2016;Malinowski & Herzing, 2015;Österblom, Olsson, Blenckner, & Furness, 2008;Spitz et al, 2011Spitz et al, , 2012. Understanding the foraging goals of marine predators is pivotal in predicting how they will respond to environmental changes in prey availability and composition (Tait, Raubenheimer, Stockin, Merriman, & Machovsky-Capuska, 2014).…”

Section: Introductionmentioning

confidence: 99%

The nutritional nexus: Linking niche, habitat variability and prey composition in a generalist marine predator

Machovsky‐Capuska

Miller

Silva

et al. 2018

Journal of Animal Ecology

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Our understanding of the niche concept will remain limited while the quantity and range of different food types eaten remain a dominant proxy for niche breadth, as this does not account for the broad ecological context that governs diet. Linking nutrition, physiology and behaviour is critical to predict the extent to which a species adjusts its nutritional niche breadth at the levels of prey ("prey composition niche," defined as the range of prey compositions eaten) and diet ("realized nutritional niche" is the range of diets composed through feeding on the prey). Here, we studied adult chick-rearing Australasian gannets Morus serrator to propose an integrative approach using sea surface temperature anomalies (SSTa), geographic location and bathymetry over different years, to explore their relationship with the nutritional composition of prey and diets (i.e. prey composition and nutritional niche breadth), habitat use and foraging behaviour. We found that gannets feed on prey that varied widely in their nutritional composition (have a broad prey composition niche), and composed diets from these prey that likewise varied in composition (have a broad realized nutritional niche), suggesting generalism at two levels of macronutrient selection. Across seasons, we established "nutritional landscapes" (hereafter nutriscapes), linking the nutritional content of prey (wet mass protein-to-lipid ratio-P:L) to the most likely geographic area of capture and bathymetry. Nutriscapes varied in their P:L from 6.06 to 15.28, over time, space and bathymetry (0-150 m). During warm water events (strong positive SSTa), gannets expanded their foraging habitat, increased their foraging trip duration and consumed prey and diets with low macronutrient content (wet mass proportions of P and L). They were also constrained to the smallest prey composition and realized nutritional niche breadths. Our findings are consistent with previous suggestions that dietary generalism evolves in heterogeneous environments, and provide a framework for understanding the nutritional goals in wild marine predators and how these goals drive ecological interactions and are, in turn, ultimately shaped by environmental fluctuations.

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Population variance in prey, diets and their macronutrient composition in an endangered marine predator, the Franciscana dolphin

Cited by 27 publications

References 53 publications

Feeding habits of the franciscana dolphin (Pontoporia blainvillei) in south-eastern Brazil

Feeding habits of the franciscana dolphin (Pontoporia blainvillei) in south-eastern Brazil

Intrapopulation variation in the diet of franciscana dolphin (Pontoporia blainvillei) off southern Brazil

The nutritional nexus: Linking niche, habitat variability and prey composition in a generalist marine predator

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