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Marine Mammals in a Changing World, 2nd Edition

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A special issue of Oceans (ISSN 2673-1924).

Deadline for manuscript submissions: closed (31 January 2024) | Viewed by 11327

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Dr. Alexander Werth

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Department of Biology, Hampden-Sydney College, Hampden-Sydney, VA 23943, USA
Interests: marine mammals and other marine vertebrates; trophic ecology; physiology, morphology, and biomechanics; evolution; conservation
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Special Issue Information

Dear Colleagues,

The past few decades have witnessed remarkable advances in our understanding of marine mammals, but many unanswered questions remain. These include fundamental questions in all biological disciplines as well as other basic and applied/clinical sciences. Major technological advances have also spurred on many recent studies of marine mammals.

Contributions for this Special Issue are invited in all areas of marine mammal research, especially those that focus on health, conservation, and physiology. In particular, contributions that focus on changing ocean habitats and technological advances in our study of changing oceans are welcomed. These can include, but are not limited to, pathogenic viruses and microbes, trophic changes, fishery impacts, habitat destruction, changes in climate/temperature, ocean acidification, ocean pollution (from noise, plastic, chemicals, etc.), vessel traffic and ship strikes, and other related topics.

Submissions may focus on any area of marine mammal research and health, including but not limited to ecology, conservation, population biology and management, behavior, habitat and distribution, genetics, evolution, physiology, anatomy, acoustics, effects of noise and pollution, and new technologies.

Dr. Alexander Werth
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Oceans is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

health
conservation
ecology
behavior
physiology
pollution

Published Papers (6 papers)

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Research

15 pages, 1418 KiB

Open AccessFeature PaperArticle

Investigation of Spatiotemporal Patterns of Harbour Porpoise (Phocoena phocoena) Strandings in Swedish Waters for Improved Monitoring and Management

by Vigge Ulfsson, Hyeyoung Kim, Linnea Cervin, Anna Roos and Aleksija Neimanis

Oceans 2024, 5(2), 166-180; https://doi.org/10.3390/oceans5020010 - 29 Mar 2024

Viewed by 676

Abstract

Harbour porpoises (Phocoena phocoena) are the only cetacean residents found year-round in Swedish waters and they are exposed to numerous natural and anthropogenic threats. Since the in situ monitoring of cetaceans can be difficult, invasive and often expensive, investigation of stranding patterns and examination of stranded animals can be used as a cost-effective source of data to study these elusive animals. The aim of this study was to investigate the spatiotemporal patterns of harbour porpoise stranding reports and the possible underlying causes in Swedish waters over a ten-year period (2014–2023). Additionally, the Swedish stranding network plays a key role in the collection of stranded carcasses for health and disease surveillance, and geographic coverage of the network also was analysed. When making spatial comparisons, the ten-year period was divided into two five-year blocks. Data on 854 stranded harbour porpoises were analysed from the coasts of the Skagerrak, Kattegat, and Baltic Seas. Both significant spatial and temporal patterns could be identified. Strandings peaked in July through September and hotspots occurred along most of the Swedish west coast, with the most frequent hotspots located around Öresund and especially the area around the Kullen peninsula. The spatial patterns of strandings found in this study are consistent with data on porpoise abundance, prey abundance, and gillnet fisheries’ efforts. The latter is known to be one of the primary causes of porpoise mortality. Furthermore, the coverage of the Swedish stranding network increased between the two periods, likely reflecting an increased awareness of the carcass-based surveillance program, and gaps requiring network expansion efforts were identified. These results also provide baseline data to enable the continued monitoring of stranding trends, as changes may indicate changes in population distribution, size or mortality rates. Full article

(This article belongs to the Special Issue Marine Mammals in a Changing World, 2nd Edition)

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23 pages, 4426 KiB

Open AccessFeature PaperArticle

Baleen–Plastic Interactions Reveal High Risk to All Filter-Feeding Whales from Clogging, Ingestion, and Entanglement

by Alexander J. Werth, Shirel R. Kahane-Rapport, Jean Potvin, Jeremy A. Goldbogen and Matthew S. Savoca

Oceans 2024, 5(1), 48-70; https://doi.org/10.3390/oceans5010004 - 01 Feb 2024

Cited by 1 | Viewed by 2218

Abstract

Baleen whales are ecosystem sentinels of microplastic pollution. Research indicates that they likely ingest millions of anthropogenic microparticles per day when feeding. Their immense prey consumption and filter-feeding behavior put them at risk. However, the role of baleen, the oral filtering structure of mysticete whales, in this process has not been adequately addressed. Using actual baleen tissue from four whale species (fin, humpback, minke, and North Atlantic right) in flow tank experiments, we tested the capture rate of plastics of varying size, shape, and polymer type, as well as chemical residues leached by degraded plastics, all of which accumulated in the baleen filter. Expanded polystyrene foam was the most readily captured type of plastic, followed by fragments, fibers, nurdles, and spherical microbeads. Nurdle and microbead pellets were captured most readily by right whale baleen, and fragments were captured by humpback baleen. Although not all differences between polymer types were statistically significant, buoyant polymers were most often trapped by baleen. Plastics were captured by baleen sections from all regions of a full baleen rack, but were more readily captured by baleen from dorsal and posterior regions. Baleen–plastic interactions underlie various risks to whales, including filter clogging and damage, which may impede feeding. We posit that plastics pose a higher risk to some whale species due to a combination of factors, including filter porosity, diet, habitat and geographic distribution, and foraging ecology and behavior. Certain whale species in specific marine regions are of the greatest concern due to plastic abundance. It is not feasible to remove all plastic from the sea; most of what is there will continue to break into ever-smaller pieces. We suggest that higher priorities be accorded to lessening humans’ dependence on plastics, restricting entry points of plastics into the ocean, and developing biodegradable alternatives. Full article

(This article belongs to the Special Issue Marine Mammals in a Changing World, 2nd Edition)

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17 pages, 3245 KiB

Open AccessArticle

Preliminary Studies on Site Fidelity, Residence Index, and Population Size of Irrawaddy Dolphins in West Penang, Malaysia

by Nurul Filzati Ali and Leela Rajamani

Oceans 2023, 4(4), 423-439; https://doi.org/10.3390/oceans4040029 - 12 Dec 2023

Viewed by 988

Abstract

The Irrawaddy dolphin is found in the coastal and estuarine areas of West Penang, Malaysia. Studies were conducted to estimate the site fidelity, residence index, and population size of Irrawaddy dolphins in West Penang. Photo-identification studies were conducted using boat surveys from 2019 to 2021. Thirty-nine marked Irrawaddy dolphins were identified, with thirty-six newly identified individuals and three individuals observed in 2013. Resightings of four individuals indicated that they were found north of Sungai Burung and Sungai Pinang in West Penang. The majority of individuals had low sighting rates, ranging from 2.6 to 7.7%, with three individuals having medium sighting rates, the highest being 15.4%. The residence index was 0.01 for all 36 individuals, and the highest value of 0.36 was recorded for one individual. Using open population models and closed models, the population size was determined to be 64 or and 52, respectively. The results suggest that although there is a population present, it is probably open, as the residence index is low. The population size appeared to be stable from 2013 to 2021. This information will inform conservation managers of the best way forward for the conservation of Irrawaddy dolphins in Penang. Full article

(This article belongs to the Special Issue Marine Mammals in a Changing World, 2nd Edition)

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14 pages, 2275 KiB

Open AccessArticle

Plastic, It’s What’s for Dinner: A Preliminary Comparison of Ingested Particles in Bottlenose Dolphins and Their Prey

by Leslie B. Hart, Miranda Dziobak, Randall S. Wells, Elizabeth Berens McCabe, Eric Conger, Tita Curtin, Maggie Knight and John Weinstein

Oceans 2023, 4(4), 409-422; https://doi.org/10.3390/oceans4040028 - 07 Dec 2023

Viewed by 1540

Abstract

Microplastic ingestion was reported for common bottlenose dolphins (Tursiops truncatus) inhabiting Sarasota Bay, FL, USA, a community that also has prevalent exposure to plasticizers (i.e., phthalates) at concentrations higher than human reference populations. Exposure sources are currently unknown, but plastic-contaminated prey could be a vector. To explore the potential for trophic exposure, prey fish muscle and gastrointestinal tract (GIT) tissues and contents were screened for suspected microplastics, and particle properties (e.g., color, shape, surface texture) were compared with those observed in gastric samples from free-ranging dolphins. Twenty-nine fish across four species (hardhead catfish, Ariopsis felis; pigfish, Orthopristis chrysoptera; pinfish, Lagodon rhomboides; and Gulf toadfish, Opsanus beta) were collected from Sarasota Bay during September 2022. Overall, 97% of fish (n = 28) had suspected microplastics, and GIT abundance was higher than muscle. Fish and dolphin samples contained fibers and films; however, foams were common in dolphin samples and not observed in fish. Suspected tire wear particles (TWPs) were not in dolphin samples, but 23.1% and 32.0% of fish muscle and GIT samples, respectively, contained at least one suspected TWP. While some similarities in particles were shared between dolphins and fish, small sample sizes and incongruent findings for foams and TWPs suggest further investigation is warranted to understand trophic transfer potential. Full article

(This article belongs to the Special Issue Marine Mammals in a Changing World, 2nd Edition)

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17 pages, 2314 KiB

Open AccessArticle

Harbor Porpoise Aggregations in the Salish Sea

by Dave Anderson, Laurie Shuster, Cindy R. Elliser, Katrina MacIver, Erin Johns Gless, Johannes Krieger and Anna Hall

Oceans 2023, 4(3), 269-285; https://doi.org/10.3390/oceans4030019 - 08 Aug 2023

Viewed by 3045

Abstract

Harbor porpoises are typically seen in small groups of 1–3 individuals, with aggregations of 20+ individuals treated as rare events. Since the 1990s, the harbor porpoise population in the Salish Sea has seen a significant recovery, and an increased number of observed aggregations that exceed the more usual small group sizes has been observed in recent years. By combining the observational data of United States and Canadian research organizations, community scientists, and whale watch captains or naturalists, we demonstrate that harbor porpoise aggregations appear to be more common than previously known, with 160 aggregations documented in 2022 alone. Behavioral data also indicate that foraging behaviors are common and social behaviors, like mating, are seen more often during these encounters compared to small groups. Other behaviors that are considered to be rare or unknown were also observed during these encounters, including cooperative foraging and vessel approach. These aggregations are likely important foraging and social gatherings for harbor porpoises. This holistic approach integrating data from two countries and multiple sources provides a population level assessment that more effectively reflects the behavior of harbor porpoises in this region, which do not recognize the socio-political boundaries imposed upon the natural world. Full article

(This article belongs to the Special Issue Marine Mammals in a Changing World, 2nd Edition)

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20 pages, 4428 KiB

Open AccessArticle

Comparative Microbial Community Analysis of Fur Seals and Aquaculture Salmon Gut Microbiomes in Tasmania

by Erin D’Agnese, Ryan J. McLaughlin, Mary-Anne Lea, Esteban Soto, Woutrina A. Smith and John P. Bowman

Oceans 2023, 4(2), 200-219; https://doi.org/10.3390/oceans4020014 - 16 Jun 2023

Cited by 1 | Viewed by 1956

Abstract

In Tasmania, Australian fur seals (Arctocephalus pusillus doriferus) regularly interact with Atlantic salmon (Salmo salmar L.) aquaculture lease operations and opportunistically consume fish. The microbial communities of seals and aquaculture salmon were analyzed for potential indicators of microbial sharing and to determine the potential effects of interactions on wild seal microbiome composition. The high-throughput sequencing of the V1–V3 region of the 16S rRNA genes from the gut microbial communities of 221 fur seals was performed: 41 males caught at farms, 50 adult scats from haul-outs near farms, 24 necropsied seals, and controls from Bass Strait breeding colonies, encompassing 56 adult scats and 50 pup swabs. QIIME2 and R Studio were used for analysis. Foraging at or near salmon farms significantly shifted seal microbiome biodiversity. Taxonomic analysis showed a greater divergence in Bacteroidota representatives in male seals captured at farms compared to all other groups. Pathogens were identified that could be monitoring targets. Potential indicator amplicon sequence variants were found across a variety of taxa and could be used as minimally invasive indicators for interactions at this interface. The diversity and taxonomic shifts in the microbial communities of seals indicate a need to further study this interface for broader ecological implications. Full article

(This article belongs to the Special Issue Marine Mammals in a Changing World, 2nd Edition)

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