Understanding the ecology and behaviour of endangered species is essential for developing effective management and conservation strategies. We used stable isotope analysis to investigate the foraging behaviour of critically endangered Mediterranean monk seals (Monachus monachus) in Greece. We measured carbon and nitrogen isotope ratios (expressed as δ(13)C and δ(15)N values, respectively) derived from the hair of deceased adult and juvenile seals and the muscle of their known prey to quantify their diets. We tested the hypothesis that monk seals primarily foraged for prey that occupy coastal habitats in Greece. We compared isotope values from seal hair to their coastal and pelagic prey (after correcting all prey for isotopic discrimination) and used these isotopic data and a stable isotope mixing model to estimate the proportion of coastal and pelagic resources consumed by seals. As predicted, we found that seals had similar δ(13)C values as many coastal prey species and higher δ(13)C values than pelagic species; these results, in conjunction with mean dietary estimates (coastal=61 % vs. pelagic=39 %), suggest that seals have a diverse diet comprising prey from multiple trophic levels that primarily occupy the coast. Marine resource managers should consider using the results from this study to inform the future management of coastal habitats in Greece to protect Mediterranean monk seals.
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http://dx.doi.org/10.1080/10256016.2014.931845 | DOI Listing |
BMC Ecol Evol
December 2024
Department of Biomedical Sciences, University of Edinburgh, Edinburgh, UK.
Background: Citizen Science (CS) offers a promising approach to enhance data collection and engage communities in conservation efforts. This study evaluates the use of CS in environmental DNA (eDNA) monitoring for Mediterranean monk seal conservation. We validated CS by assessing the effectiveness of a newly developed CS-friendly filtration system called "WET" (Water eDNA Trap) in eDNA detection, addressing technical challenges, and analysing volunteer faults.
View Article and Find Full Text PDFDis Aquat Organ
November 2024
Faculty of Veterinary Medicine, University of Zagreb, 10000 Zagreb, Croatia.
Sci Rep
November 2024
School of Life and Environmental Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia.
Determining the factors influencing habitat selection and hunting success in top predators is crucial for understanding how these species may respond to environmental changes. For marine top predators, such factors have been documented in pelagic foragers, with habitat use and hunting success being linked to chlorophyll-a concentrations, sea surface temperature and light conditions. In contrast, little is known about the determinants of benthic marine predators.
View Article and Find Full Text PDFScience
September 2024
University of Hawai'i Sea Grant College Program, School of Ocean and Earth Science and Technology, Honolulu, HI, USA.
Abandoned, lost, or otherwise discarded fishing gear causes harm to marine species and ecosystems. To mitigate the destruction wrought by this ocean plastic debris, various cleanup programs have been established, though to our knowledge the benefits of such efforts to marine species and ecosystems have not yet been empirically demonstrated. We examined more than 40 years of Hawaiian monk seal marine debris entanglement records before and after large-scale marine debris removal efforts were initiated in the Northwestern Hawaiian Islands, demonstrating a substantial reduction in entanglement rates where debris removal effort was most concentrated.
View Article and Find Full Text PDFEcohealth
December 2024
NOAA, Hawaiian Monk Seal Research Program, Honolulu, USA.
Toxoplasmosis is a disease of primary concern for Hawaiian monk seals (Neomonachus schauinslandi), due to its apparently acute lethality and especially heavy impacts on breeding female seals. The disease-causing parasite, Toxoplasma gondii, depends on cats to complete its life cycle; thus, in order to understand how this pathogen infects marine mammals, it is essential to understand aspects of the terrestrial ecosystem and land-to-sea transport. In this study, we constructed a three-tiered model to assess risk of Hawaiian monk seal exposure to T.
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