Variation of blubber thickness for three marine mammal species in the southern Baltic Sea
Evaluating populational trends of health condition has become an important topic for marine mammal populations under the Marine Strategy Framework Directive (MSFD). In the Baltic Sea, under the recommendation of Helsinki Commission (HELCOM), efforts have been undertaken to use blubber thickness as a...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2022-11-01
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| Series: | Frontiers in Physiology |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fphys.2022.880465/full |
| _version_ | 1811317545785884672 |
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| author | Ursula Siebert Miguel L. Grilo Tina Kesselring Kristina Lehnert Katrin Ronnenberg Iwona Pawliczka Anders Galatius Line A. Kyhn Michael Dähne Anita Gilles |
| author_facet | Ursula Siebert Miguel L. Grilo Tina Kesselring Kristina Lehnert Katrin Ronnenberg Iwona Pawliczka Anders Galatius Line A. Kyhn Michael Dähne Anita Gilles |
| author_sort | Ursula Siebert |
| collection | DOAJ |
| description | Evaluating populational trends of health condition has become an important topic for marine mammal populations under the Marine Strategy Framework Directive (MSFD). In the Baltic Sea, under the recommendation of Helsinki Commission (HELCOM), efforts have been undertaken to use blubber thickness as an indicator of energy reserves in marine mammals. Current values lack geographical representation from the entire Baltic Sea area and a large dataset is only available for grey seals (Halichoerus grypus) from Sweden and Finland. Knowledge on variation of blubber thickness related to geography throughout the Baltic Sea is important for its usage as an indicator. Such evaluation can provide important information about the energy reserves, and hence, food availability. It is expected that methodological standardization under HELCOM should include relevant datasets with good geographical coverage that can also account for natural variability in the resident marine mammal populations. In this study, seasonal and temporal trends of blubber thickness were evaluated for three marine mammal species—harbor seal (Phoca vitulina), grey seal (Halichoerus grypus) and harbor porpoise (Phocoena phocoena)—resident in the southern Baltic Sea collected and investigated under stranding networks. Additionally, the effects of age, season and sex were analyzed. Seasonal variation of blubber thickness was evident for all species, with harbor seals presenting more pronounced effects in adults and grey seals and harbor porpoises presenting more pronounced effects in juveniles. For harbor seals and porpoises, fluctuations were present over the years included in the analysis. In the seal species, blubber thickness values were generally higher in males. In harbor seals and porpoises, blubber thickness values differed between the age classes: while adult harbor seals displayed thicker blubber layers than juveniles, the opposite was observed for harbor porpoises. Furthermore, while an important initial screening tool, blubber thickness assessment cannot be considered a valid methodology for overall health assessment in marine mammals and should be complemented with data on specific health parameters developed for each species. |
| first_indexed | 2024-04-13T12:10:03Z |
| format | Article |
| id | doaj.art-00f2f0992b2e420aae15aef43d9d2f9f |
| institution | Directory Open Access Journal |
| issn | 1664-042X |
| language | English |
| last_indexed | 2024-04-13T12:10:03Z |
| publishDate | 2022-11-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Physiology |
| spelling | doaj.art-00f2f0992b2e420aae15aef43d9d2f9f2022-12-22T02:47:30ZengFrontiers Media S.A.Frontiers in Physiology1664-042X2022-11-011310.3389/fphys.2022.880465880465Variation of blubber thickness for three marine mammal species in the southern Baltic SeaUrsula Siebert0Miguel L. Grilo1Tina Kesselring2Kristina Lehnert3Katrin Ronnenberg4Iwona Pawliczka5Anders Galatius6Line A. Kyhn7Michael Dähne8Anita Gilles9Institute for Terrestrial and Aquatic Wildlife Research (ITAW), University of Veterinary Medicine Hannover Foundation, Büsum, GermanyMARE—Marine and Environmental Sciences Centre, ISPA—Instituto Universitário de Ciências Psicológicas, Sociais e da Vida, Lisbon, PortugalInstitute for Terrestrial and Aquatic Wildlife Research (ITAW), University of Veterinary Medicine Hannover Foundation, Büsum, GermanyInstitute for Terrestrial and Aquatic Wildlife Research (ITAW), University of Veterinary Medicine Hannover Foundation, Büsum, GermanyInstitute for Terrestrial and Aquatic Wildlife Research (ITAW), University of Veterinary Medicine Hannover Foundation, Büsum, GermanyDepartment of Oceanography and Geography, Krzysztof Skóra Hel Marine Station, University of Gdansk, Hel, PolandMarine Mammal Research, Institute of Ecoscience, Aarhus University, Roskilde, DenmarkMarine Mammal Research, Institute of Ecoscience, Aarhus University, Roskilde, DenmarkGerman Oceanographic Museum, Stralsund, GermanyInstitute for Terrestrial and Aquatic Wildlife Research (ITAW), University of Veterinary Medicine Hannover Foundation, Büsum, GermanyEvaluating populational trends of health condition has become an important topic for marine mammal populations under the Marine Strategy Framework Directive (MSFD). In the Baltic Sea, under the recommendation of Helsinki Commission (HELCOM), efforts have been undertaken to use blubber thickness as an indicator of energy reserves in marine mammals. Current values lack geographical representation from the entire Baltic Sea area and a large dataset is only available for grey seals (Halichoerus grypus) from Sweden and Finland. Knowledge on variation of blubber thickness related to geography throughout the Baltic Sea is important for its usage as an indicator. Such evaluation can provide important information about the energy reserves, and hence, food availability. It is expected that methodological standardization under HELCOM should include relevant datasets with good geographical coverage that can also account for natural variability in the resident marine mammal populations. In this study, seasonal and temporal trends of blubber thickness were evaluated for three marine mammal species—harbor seal (Phoca vitulina), grey seal (Halichoerus grypus) and harbor porpoise (Phocoena phocoena)—resident in the southern Baltic Sea collected and investigated under stranding networks. Additionally, the effects of age, season and sex were analyzed. Seasonal variation of blubber thickness was evident for all species, with harbor seals presenting more pronounced effects in adults and grey seals and harbor porpoises presenting more pronounced effects in juveniles. For harbor seals and porpoises, fluctuations were present over the years included in the analysis. In the seal species, blubber thickness values were generally higher in males. In harbor seals and porpoises, blubber thickness values differed between the age classes: while adult harbor seals displayed thicker blubber layers than juveniles, the opposite was observed for harbor porpoises. Furthermore, while an important initial screening tool, blubber thickness assessment cannot be considered a valid methodology for overall health assessment in marine mammals and should be complemented with data on specific health parameters developed for each species.https://www.frontiersin.org/articles/10.3389/fphys.2022.880465/fullblubber thicknessharbor sealsgrey sealsharbor porpoisesnatural variationsHELCOM area |
| spellingShingle | Ursula Siebert Miguel L. Grilo Tina Kesselring Kristina Lehnert Katrin Ronnenberg Iwona Pawliczka Anders Galatius Line A. Kyhn Michael Dähne Anita Gilles Variation of blubber thickness for three marine mammal species in the southern Baltic Sea Frontiers in Physiology blubber thickness harbor seals grey seals harbor porpoises natural variations HELCOM area |
| title | Variation of blubber thickness for three marine mammal species in the southern Baltic Sea |
| title_full | Variation of blubber thickness for three marine mammal species in the southern Baltic Sea |
| title_fullStr | Variation of blubber thickness for three marine mammal species in the southern Baltic Sea |
| title_full_unstemmed | Variation of blubber thickness for three marine mammal species in the southern Baltic Sea |
| title_short | Variation of blubber thickness for three marine mammal species in the southern Baltic Sea |
| title_sort | variation of blubber thickness for three marine mammal species in the southern baltic sea |
| topic | blubber thickness harbor seals grey seals harbor porpoises natural variations HELCOM area |
| url | https://www.frontiersin.org/articles/10.3389/fphys.2022.880465/full |
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