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

This study was supported by the Spanish Ministry of Economy, Industry and Competitiveness and EU ERDF funds through the projects CGL2015-66966-C2-1-2-R and CGL2017-89905-R. M.M. was supported by a research contract Ramon y Cajal from the MINECO (RYC-2015-19231) , and A.CA. by a contract Juan de la Cierva Incorporacion (IJCI-2014-20744; Spanish Ministry of Economy and Competitiveness, Spain) and a PostDoc contract Programa Vicent Mut of Govern Balear, Spain (PD/039/2017) . NS was supported by the Bekker programme of the Polish National Agency for Academic Exchange (NAWA) . Acknowledgements of specific institutions and people sharing their valuable strandings database is in Table B3.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.Spanish Government EU ERDF funds CGL2015-66966-C2-1-2-R CGL2017-89905-Rresearch contract Ramon y Cajal from the MINECO RYC-2015-19231 contract Juan de la Cierva Incorporacion (Spanish Ministry of Economy and Competitiveness, Spain) IJCI-2014-20744PostDoc contract Programa Vicent Mut of Govern Balear, Spain PD/039/2017Polish National Agency for Academic Exchange (NAWA

Seal carrion is a predictable resource for coastal ecosystems

This work was supported in part by NERC National Capability funding to the Sea Mammal Research Unit (grant no. SMRU1001). MMQ was funded by a College of Medical, Veterinary and Life Sciences PhD Scholarship (University of Glasgow) to undertake this research.The timing, magnitude, and spatial distribution of resource inputs can have large effects on dependent organisms. Few studies have examined the predictability of such resources and no standard ecological measure of predictability exists. We examined the potential predictability of carrion resources provided by one of the UK's largest grey seal (Halichoerus grypus) colonies, on the Isle of May, Scotland. We used aerial (11 years) and ground surveys (3 years) to quantify the variability in time, space, quantity (kg), and quality (MJ) of seal carrion during the seal pupping season. We then compared the potential predictability of seal carrion to other periodic changes in food availability in nature. An average of 6893 kg of carrion ∙yr−1 corresponding to 110.5 × 103 MJ yr−1 was released for potential scavengers as placentae and dead animals. A fifth of the total biomass from dead seals was consumed by the end of the pupping season, mostly by avian scavengers. The spatial distribution of carcasses was similar across years, and 28% of the area containing >10 carcasses ha−1 was shared among all years. Relative standard errors (RSE) in space, time, quantity, and quality of carrion were all below 34%. This is similar to other allochthonous-dependent ecosystems, such as those affected by migratory salmon, and indicates high predictability of seal carrion as a resource. Our study illustrates how to quantify predictability in carrion, which is of general relevance to ecosystems that are dependent on this resource. We also highlight the importance of carrion to marine coastal ecosystems, where it sustains avian scavengers thus affecting ecosystem structure and function.PostprintPeer reviewe

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

Grey seal Halichoerus grypus breeding sites contribute substantial carrion biomass to the Firth of Forth

Decomposing organic matter is central to the recycling of energy and nutrients in all ecosystems. Few studies have investigated the role of animal carrion biomass in ecosystem functioning, and quantitative data on carrion biomass are lacking. The role of carrion inputs in the marine environment specifically, is poorly understood. The grey seal (Halichoerus grypus) breeding colony on the Isle of May in the Firth of Forth, Scotland, provides insight into the contribution of regular carrion pulses to the surrounding marine ecosystem. This study analysed three breeding locations with a range of topographies, elevations, and tidal influences. Carcasses were mapped from aerial images and ground visual surveys in the 2008 and 2012 breeding seasons. Generalised Linear Mixed Models (GLMMs) were used to explore the degree to which breeding location and the position of a carcass influenced its availability to marine scavengers. Carcasses closer to shore were more likely to be completely displaced to the marine environment and this effect varied with breeding location. An approximate 0.9 to 1.3 tonnes of biomass per hectare of breeding site per year were released into the marine system. For carcasses which were below the high-water spring tide range but remained on shore we quantified the typical duration of submersion to range from 5% to 44% of the time carcasses were ashore. Additionally, up to 808 kg of carrion were accessible to marine scavengers while washed by tides. Our results suggest breeding colonies of grey seals may contribute significantly to the carrion biomass available in local marine systems

Towards Quantifying Carrion Biomass in Ecosystems

The decomposition of animal biomass (carrion) contributes to the recycling of energy and nutrients through ecosystems. Whereas the role of plant decomposition in ecosystems is broadly recognised, the significance of carrion to ecosystem functioning remains poorly understood. Quantitative data on carrion biomass are lacking and there is no clear pathway towards improved knowledge in this area. Here, we present a framework to show how quantities derived from individual carcasses can be scaled up using population metrics, allowing for comparisons among ecosystems and other forms of biomass. Our framework facilitates the generation of new data that is critical to building a quantitative understanding of the contribution of carrion to trophic processes and ecosystem stocks and flows.PSB was funded by the Australian Research Council (DE150100026). JKB was supported by grants from the United States National Science Foundation (NSF ID#1545611, NSF ID#1556676)

Echoing the need to quantify carrion biomass production

No abstract available

Comparing scavenging in marine and terrestrial ecosystems: a case study with fish and gull carcasses in a small Mediterranean island

Carrion consumption by scavengers is a key component of both terrestrial and aquatic food webs. However, there are few direct comparisons of the structure and functioning of scavenging communities in different ecosystems. Here, we monitored the consumption of 23 fish (seabream Sparus aurata) and 34 bird (yellow-legged gull Larus michahellis) carcasses on a small Mediterranean island (Isla Grosa, southeastern Spain) and surrounding waters in summer to compare the structure of the scavenger assemblages and their carrion consumption efficiencies in terrestrial and shallow water habitats. Scavenging was highly efficient both in marine and terrestrial environments, especially in the presence of a highly abundant vertebrate scavenger species, the yellow-legged gull. The vertebrate scavenger community was richer in the marine environment, whereas the invertebrate community was richer on land. The scavenger network was usually well-structured (i.e., nested), with the exception of the community associated with fish terrestrial carcasses, which were almost monopolized by yellow-legged gulls. In contrast, gulls left conspecific carcasses untouched, thus allowing longer persistence of gull carcasses on land and their exploitation by a diverse insect community. Our study shows important differences in the scavenging process associated with environment and carcass type. Promising avenues for further eco-evolutionary and applied research arise from the comparison of scavenging processes in terrestrial and marine ecosystems, from small islands to continents.D.R.-G. was granted by the European Social Fund and the Chamber of Commerce of Granada, Z.M.-R. by a postdoctoral contract co-funded by the Generalitat Valenciana and the European Social Fund (APOSTD/2019/016), and E.S.-G. and M.M. research contracts Ramón y Cajal from the MINECO (RYC-2019-027216-I and RYC-2015-19231, respectively). This study was funded by the Spanish Ministry of Economy, Industry and Competitiveness and EU ERDF funds through the project CGL2017-89905-R. Funding for open access charge: Universidad de Granada / CBUA