Trophic Ecology of Humpback Whales (Megaptera novaeangliae) in the Magellan Strait as Indicated by Carbon and Nitrogen Stable Isotopes

Haro, Daniela; Riccialdelli, Luciana; Acevedo, Jorge; Aguayo‐Lobo, Anelio; Montiel, Américo

doi:10.1578/am.42.2.2016.233

Cited by 21 publications

(10 citation statements)

References 32 publications

(46 reference statements)

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“…In this regard, there is an urgent need for the implementation of effective action plans for the scientific treatment of stranded whales and dolphins, if we aim to understand the impacts of the ingestion of marine litter in megafauna. This is particularly important since researchers are adopting non-invasive methods (e.g., stable isotopes, DNA analysis) for both live (Haro et al, 2016) and stranded charismatic animals. At present, it is difficult to understand the magnitude of the plastic ingestion problem for marine mammals in the SE Pacific.…”

Section: Ingestion Of Plasticsmentioning

confidence: 99%

Impacts of Marine Plastic Pollution From Continental Coasts to Subtropical Gyres—Fish, Seabirds, and Other Vertebrates in the SE Pacific

et al. 2018

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Anthropogenic Marine Debris (AMD) in the SE Pacific has primarily local origins from land-based sources, including cities (coastal and inland), beach-goers, aquaculture, and fisheries. The low frequency of AMD colonized by oceanic biota (bryozoans, lepadid barnacles) suggests that most litter items from coastal waters of the Humboldt Current System (HCS) are pulled offshore into the South Pacific Subtropical Gyre (SPSG). The highest densities of floating micro-and macroplastics are reported from the SPSG. An extensive survey of photographic records, unpublished data, conference proceedings, and published studies revealed interactions with plastics for 97 species in the SE Pacific, including 20 species of fish, 5 sea turtles, 53 seabirds, and 19 marine mammals. Sea turtles are most affected by interactions with plastics, underlined by the fact that 4 of the 5 species suffer both from entanglement and ingestion. Reports gathered in this review suggest that interactions along the continental coast are mostly via entanglement. High frequencies of microplastic ingestion have been reported from planktivorous fish and seabirds inhabiting the oceanic waters and islands exposed to high densities of microplastics concentrated by oceanic currents in the SPSG. Our review also suggests that some species from the highly productive HCS face the risk of negative interactions with AMD, because food and plastic litter are concentrated in coastal front systems. In order to improve the conservation of marine vertebrates, especially of sea turtles, urgent measures of plastic reduction are needed.

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Section: Ingestion Of Plasticsmentioning

confidence: 99%

Impacts of Marine Plastic Pollution From Continental Coasts to Subtropical Gyres—Fish, Seabirds, and Other Vertebrates in the SE Pacific

et al. 2018

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“…Prior to analysis, all tissue samples were freeze-dried for 48 h (Haro et al, 2016) and then homogenized with a mortar and pestle. Owing to the high lipid content in whale skin and fish muscle, as indicated by C:N > 3.5, lipids were extracted from these samples to reduce biases resulting from 13 C depletion of lipids (Post et al, 2007).…”

Section: Stable Isotope Analysismentioning

confidence: 99%

“…As the cellular component and whole blood of seabirds have a low lipid content (i.e., C:N < 3.5), lipid extraction from these samples was unnecessary (Post et al, 2007). A 0.400-0.600 mg subsample was removed from each dried and homogenized sample, sealed in a 5 × 9 mm tin capsule and placed in a plastic tray with labeled divides (Witteveen et al, 2009;Haro et al, 2016). Carbon and nitrogen isotopic ratios were quantified using a continuous flow mass spectrometer coupled with an elemental analyzer (University of Windsor, Ontario).…”

Section: Stable Isotope Analysismentioning

confidence: 99%

Dietary Niche Shifts of Multiple Marine Predators under Varying Prey Availability on the Northeast Newfoundland Coast

et al. 2017

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Understanding species interactions among top marine predators and interactions with their prey can provide important insight into community-level responses to changing prey availability and the role of apex predators as indicators of ecosystem change. On the northeast Newfoundland coast, marine predators rely on capelin (Mallotus villosus), a dominant forage fish, as a food source. Capelin migrate into coastal regions to spawn during July, essentially transforming the food supply from low during early summer (i.e., pre-spawning) to high later in the summer (i.e., spawning). During July-August, 2016, we used stable isotopic ratios of nitrogen (δ 15 N) and carbon (δ 13 C) to investigate shifts in dietary niche metrics at the predator group-level (trophic position, dietary niche breadth) and community-level (niche overlap, trophic diversity) for multiple marine predators under varying capelin availability. Predator groups included non-breeding shearwaters (great shearwater Ardenna gravis, sooty shearwater A. grisea), humpback whales (Megaptera novaeangliae), and gull chicks (herring gull Larus argentatus, great black-backed gull Larus marinus). We also tested the sensitivity of community-level dietary metrics to a variety of published trophic discrimination factors. Tissue samples from shearwaters (blood cellular component), gull chicks (whole blood), and whales (skin), representing average diets over 2-3 weeks, were collected during three periods (early, mid, late) corresponding to increasing capelin availability. Isotopic niche breadth (Standard Ellipse Area, SEA b ) narrowed and trophic position shifted toward higher δ 15 N for all predator groups as capelin availability increased, suggesting a higher reliance on capelin. Trophic diversity (distance to centroid) decreased with increased capelin availability, while pairwise niche overlap between predator groups was highly variable and sensitive to trophic discrimination factors. Findings suggest that although capelin is the dominant forage fish during the summer, predators rely on capelin as prey to varying degrees. Combining species-and community-level metrics of dietary niche and trophic diversity may provide a more complete picture of predator responses to prey availability and, thus, may be important monitoring tools to indicate changes in the food supply of marine predators.

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“…The Magellan Strait hosts a feeding area for humpback whales located in the western section of the Strait (Gibbons et al, 2003;Acevedo, 2005) where some sei whales were also sighted. The diet of this aggregation of humpback whales is based on Fueguian sprat, euphausiid (E. lucens), and lobster krill (M. gregaria) (Acevedo et al, 2011;Haro, 2013;Haro et al, 2016). Oceanographic cruise surveys in the Magellan Strait report that the zooplankton community is dominated by the euphausiid E. vallentini; the copepods C. simillimus, C. australis, and Drepanopus forcipatus; and the amphipods Themisto (= Parathemisto) gaudichaudii and Cyphocaris faurei (Antezana et al, 1992;Costanzo & Crescenti, 1997;Guglielmo et al, 1997;Marín & Delgado, 2001;Palma & Aravena, 2001), with copepods and euphausiids being the dominant taxa in the central section of the Magellan Strait (called Paso Ancho) (Antezana et al, 1996;Defren-Janson et al, 1999).…”

Section: Photo-identified Whalesmentioning

confidence: 99%

Occurrence of Sei Whales (Balaenoptera borealis) in the Magellan Strait from 2004-2015, Chile

Acevedo¹,

Aguayo‐Lobo²,

González³

et al. 2017

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Trophic Ecology of Humpback Whales (Megaptera novaeangliae) in the Magellan Strait as Indicated by Carbon and Nitrogen Stable Isotopes

Cited by 21 publications

References 32 publications

Impacts of Marine Plastic Pollution From Continental Coasts to Subtropical Gyres—Fish, Seabirds, and Other Vertebrates in the SE Pacific

Impacts of Marine Plastic Pollution From Continental Coasts to Subtropical Gyres—Fish, Seabirds, and Other Vertebrates in the SE Pacific

Dietary Niche Shifts of Multiple Marine Predators under Varying Prey Availability on the Northeast Newfoundland Coast

Occurrence of Sei Whales (Balaenoptera borealis) in the Magellan Strait from 2004-2015, Chile

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