Past, present and future of the ecosystem services provided by cetacean carcasses

Ecosystem services associated with cetacean strandings have been altered by humans through exploitation of wild populations during the whaling era and more recently by regulations on carcass management and disposal to abide by environmental health requirements. Here, we systematically review the scientific literature and gather data on cetacean strandings worldwide to: 1) identify the ecosystem services provided by stranded cetacean carcasses in the past and present; 2) estimate the density of cetacean strandings currently occurring in selected coastal areas around the globe, and analyse its association with human population density and regulations; and 3) identify and discuss the regulations and methods concerned with whale carcass disposal in specific regions of the world. Our literature review revealed that stranded cetacean carcasses have provided a rich and varied array of provisioning, regulating, cultural, and supporting ecosystem services to ancient and modern civilisations worldwide. Also, we found that the current density of stranded carcasses (mean: 0.090 strandings • year−1 • km−1; range: 0.001–0.978) and the disposal methods widely varied across the studied regions and countries. In addition, neither human population density nor the existence of regulations were good predictors of stranding densities. Finally, we provide recommendations for the future management of stranded cetacean carcasses, by identifying those disposal methods that minimize costs and maximize ecosystem functions and services. In particular, we encourage natural decomposition in situ whenever possible; otherwise, the present coastal management strategies could be improved by including zoning, seasonal use limitation and educational outreach depending upon the local scenario. Overall, further socio-ecological research is strongly needed to guide stranded cetacean carcass management towards enhancing the net benefits that humans and ecosystems gain from carcasses, especially considering that coastal areas become more populated, new disposal regulations are approved, and cetacean populations are recovering – and thus strandings may become more frequent

Food resource utilisation by the Magellanic penguin evaluated through stable-isotope analysis: Segregation by sex and age and influence on offspring quality

We used stable-isotope analysis (SIA) to evaluate sources of variation in the diet of and prey selection by Magellanic penguins Spheniscus magellanicus breeding on the Argentinean Patagonia coast. Our aim was to determine potential sources of variation in diet, focusing mainly on sex and age, although geographic and temporal effects were also taken into account. In addition, we evaluated how prey selection affects offspring quality. We measured stable nitrogen (δ15N) and carbon (δ13C) isotope values in whole blood of chicks (n = 98), yearlings (n = 15) and adults (n = 143) in 9 different breeding colonies during 2 consecutive breeding seasons (1999 and 2000). We also measured stable isotope values in representative prey consumed by this species. Stable nitrogen and carbon isotope values in blood for penguins varied from 17.8 to 20.0‰ and from -18.1 to -14.8‰, respectively. Both colony and season had a significant effect on the 2 isotope signatures. Adult males had higher blood δ15N and δ13C values than females. Age significantly affected both δ15N and δ13C values, with chicks showing the highest and yearlings the lowest δ15N values. Chicks showed lower δ13C values than yearlings and adults. Mean prey δ15N values ranged from 13.6‰ in squid to 18.0‰ in octopus. As anchovy, the main prey consumed by the species in the study area, did not differ from other fish species (hake) in its δ15N value, we used it to represent a fish dietary alternative. Using a 2-source (anchovy and squid) isotopic mixing model, we determined that the mean proportion of anchovy in the diet was 49% for yearlings, 76% for chicks, and 69% and 67% for adult males and females, respectively. Sex and age differences in diet, as revealed by stable isotopes, may be the consequence of individual morphology (sexual size dimorphism) and reproductive constraints imposed by chick development since growing young require more nutritive prey than adults and yearlings. This reasoning would also explain the significant and positive correlation found between proportion of anchovy in the diet and body condition of chicks.Fil: Forero, Manuela G.. Consejo Superior de Investigaciones Científicas. Instituto Mediterráneo de Estudios Avanzados; EspañaFil: Hobson, Keith A.. Canadian Wildlife Service; Canadá. University of Saskatchewan; CanadáFil: Bortolotti, Gary R.. University of Saskatchewan; CanadáFil: Donázar, Jose A.. Consejo Superior de Investigaciones Científicas; EspañaFil: Bertellotti, Néstor Marcelo. Consejo Superior de Investigaciones Científicas; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Blanco, G.. Instituto de Investigación en Recursas Cinegéticos; Españ