Steller Sea Research Articles

Long‐term data reveals increase in vehicle collisions of endangered birds in Hokkaido, Japan

AbstractWildlife‐vehicle collisions have significant consequences for both humans and animals, including injuries, deaths, and vehicle damage. Therefore, analysis of accident data is important for planning countermeasures and appropriate wildlife management. In this research field, roadkill incidents have been extensively studied in many taxa, while railway accidents have received less attention despite their obvious impact on wildlife. Here we applied a Bayesian state‐space model to 31 years of collision data, both on railways and on roads, collected by the Ministry of the Environment in Hokkaido prefecture, Japan, to reveal the spatiotemporal dynamics of accidents for white‐tailed eagles, Steller's sea eagles, and red‐crowned cranes, for which over hundred accidents were reported in the data. Our analysis suggested that the mean annual number of individuals collected per collision site across Hokkaido increased 47,377‐fold in the white‐tailed eagle, 40,277‐fold in the Steller's sea eagle, and 50,584‐fold in the red‐crowned crane between 1991 and 2021. There have been concerns about the impact of traffic accidents on the population dynamics of these endangered birds, but no formal analyses have been conducted. Our analysis showed numerically that the negative impact has been increasing annually. These results suggest that long‐term data accumulation over large spatial scales allows us to understand the dynamics of accidents and predict potential factors underlying collision risks.

БЕЛОПЛЕЧИЕ ОРЛАНЫ (HALIAEETUS PELAGICUS) ЗИМОЙ В АНТРОПОГЕННЫХ УСЛОВИЯХ КАМЧАТКИ И СЕВЕРНЫХ КУРИЛЬСКИХ ОСТРОВОВ

In winter, in Kamchatka and Northern Kuril Islands (Paramushir Island) Steller's Sea eagles regularly patrol fishing vessels near marine harbors and control their unloading process to be able to eat the discarded and injured fish, other seafood and food household wastes from the ships. They also willingly use landfills and industrial water discharges as habitats in case food wastes are present there. Besides, in Kamchatka Steller's Sea eagles use artificial structures (in particular, power transmission towers) as roost sites, can pick up animals hit by cars on the roads as prey and land on the snow-free concrete surface of the runway at the airport (Yelizovo city). This is similar to the well-known situation for the wintering conditions of Sea eagles from Japan, and the difference is that the larger portion of the local winter population of Sea eagles winters in Hokkaido under the anthropogenic conditions, and a smaller portion winters in Kamchatka.

From teeth to pad: tooth loss and development of keratinous structures in sirenians.

Sirenians are a well-known example of morphological adaptation to a shallow-water grazing diet characterized by a modified feeding apparatus and orofacial morphology. Such adaptations were accompanied by an anterior tooth reduction associated with the development of keratinized pads, the evolution of which remains elusive. Among sirenians, the recently extinct Steller's sea cow represents a special case for being completely toothless. Here, we used μ-CT scans of sirenian crania to understand how motor-sensor systems associated with tooth innervation responded to innovations such as keratinized pads and continuous dental replacement. In addition, we surveyed nine genes associated with dental reduction for signatures of loss of function. Our results reveal how patterns of innervation changed with modifications of the dental formula, especially continuous replacement in manatees. Both our morphological and genomic data show that dental development was not completely lost in the edentulous Steller's sea cows. By tracing the phylogenetic history of tooth innervation, we illustrate the role of development in promoting the innervation of keratinized pads, similar to the secondary use of dental canals for innervating neomorphic keratinized structures in other tetrapod groups.

An integrated system to assess marine extinctions.

More than 20 global marine extinctions and over 700 local extinctions have reportedly occurred during the past 500 years. However, available methods to determine how many of these species can be confidently declared true disappearances tend to be data-demanding, time-consuming, and not applicable to all taxonomic groups or scales of marine extinctions (global [G] and local [L]). We developed an integrated system to assess marine extinctions (ISAME) that can be applied to any taxonomic group at any geographic scale. We applied the ISAME method to 10 case studies to illustrate the possible ways in which the extinction status of marine species can be categorized as unverified, possibly extinct, or extinct. Of the 10 case studies we assessed, the ISAME method concludes that 6 should be categorized as unverified extinctions due to problems with species' identity and lack of reliable evidence supporting their disappearance (periwinkle-Littoraria flammea [G], houting-Coregonus oxyrinchus [G], long-spined urchin-Diadema antillarum [L], smalltooth sawfish-Pristis pectinata [L], and largetooth sawfish-P. pristis [L]). In contrast, ISAME classified the Guadalupe storm-petrel (Oceanodroma macrodactyla [G]) and the lost shark (Carcharhinus obsolerus [G]) as possibly extinct because the available evidence indicates that their extinction is plausible-while the largetooth sawfish [L] and Steller's sea cow (Hydrodamalis gigas [G]) were confirmed to be extinct. Determining whether a marine population or species is actually extinct or still extant is needed to guide conservation efforts and prevent further biodiversity losses.

Evolution of an extreme hemoglobin phenotype contributed to the sub-Arctic specialization of extinct Steller's sea cows.

The extinct Steller's sea cow (Hydrodamalis gigas; †1768) was a whale-sized marine mammal that manifested profound morphological specializations to exploit the harsh coastal climate of the North Pacific. Yet despite first-hand accounts of their biology, little is known regarding the physiological adjustments underlying their evolution to this environment. Here, the adult-expressed hemoglobin (Hb; a2β/δ2) of this sirenian is shown to harbor a fixed amino acid replacement at an otherwise invariant position (β/δ82Lys→Asn) that alters multiple aspects of Hb function. First, our functional characterization of recombinant sirenian Hb proteins demonstrate that the Hb-O2 affinity of this sub-Arctic species was less affected by temperature than those of living (sub)tropical sea cows. This phenotype presumably safeguarded O2 delivery to cool peripheral tissues and largely arises from a reduced intrinsic temperature sensitivity of the H. gigas protein. Additional experiments on H. gigas β/δ82Asn→Lys mutant Hb further reveal this exchange renders Steller's sea cow Hb unresponsive to the potent intraerythrocytic allosteric effector 2,3-diphosphoglycerate, a radical modification that is the first documented example of this phenotype among mammals. Notably, β/δ82Lys→Asn moreover underlies the secondary evolution of a reduced blood-O2 affinity phenotype that would have promoted heightened tissue and maternal/fetal O2 delivery. This conclusion is bolstered by analyses of two Steller's sea cow prenatal Hb proteins (Hb Gower I; z2e2 and HbF; a2g2) that suggest an exclusive embryonic stage expression pattern, and reveal uncommon replacements in H. gigas HbF (g38Thr→Ile and g101Glu→Asp) that increased Hb-O2 affinity relative to dugong HbF. Finally, the β/δ82Lys→Asn replacement of the adult/fetal protein is shown to increase protein solubility, which may have elevated red blood cell Hb content within both the adult and fetal circulations and contributed to meeting the elevated metabolic (thermoregulatory) requirements and fetal growth rates associated with this species cold adaptation.

ЭКОЛОГИЯ ПИТАНИЯ СИВУЧА С РЕПРОДУКТИВНОГО ЛЕЖБИЩА НА МЫСЕ КОЗЛОВА (ВОСТОЧНАЯ КАМЧАТКА)

We studied the Steller's sea lion Eumetopias jubatus feeding ecology based on undigested food items found in feces at the Kozlova Cape rookery, Eastern coast of Kamchatka Peninsula, in summers (2004 through 2008). Atka mackerel Pleurogrammus monopterygius and walleye pollock Theragra chalcogramma were dominant in a sea lion diet hauled out at Kozlova Cape rookery in terms of frequency of occurrence. Less frequently occurred were Pacific sand lance Ammodytes hexapterus, Threespine stickleback Gasterosteus aculaeatus, Smelt Osmerus mordax, Sculpins Cottidae, Pacific sandfish Trichodon trichodon, Flatfishes Pleuronectidae, Salmon Oncorhynchus sp., Pacific cod Gadus macrocephalus, and Squid and Octopus Cephalopoda. The contribution of the other food items was not significant. Diet diversity median during sea lion single foraging trip was two prey items, range being one to nine Atka mackerel and Walleye pollock as the major prey objects. Most of sea lion food items were referred to species featuring a marked seasonal presence near the shore or on the shelf. Sea lions feed near the rookery close to the shore on seasonal food aggregations common to the area. Seasonal prey aggregations can be extremely important for breeding animals due to increasing the efficiency of food search and capture, which in turn can affect the reproductive success of animals and their survival. In this regard, the stability of the food resource near Kozlova Cape Rookery may influence sea lion population status there.

Molecular characterization of Trichomonas gypaetinii isolated from the upper alimentary tract of Steller's sea eagles (Haliaeetus pelagicus) and white-tailed sea eagles (Haliaeetus albicilla) in Hokkaido, Japan.

Recent phylogenetic and morphologic studies of Trichomonas spp. suggests that there are more than 3 species that infect the upper alimentary tract of wild birds, which include T. gallinae, T. stableri, and T. gypaetinii. In this study, investigations were conducted on the prevalence of trichomonads in the upper alimentary tract of 12 Steller's sea eagles (Haliaeetus pelagicus) and 18 white-tailed sea eagles (H. albicilla). All birds were rescued from the wild and kept at a rehabilitation facility in Hokkaido, Japan, for variable durations and did not show any symptoms of trichomonosis. The ITS1-5.8SrRNA-ITS2 (ITS) genomic region of Trichomonas spp. was detected from 29 samples by PCR, and flagellates were confirmed from 4 samples by culture. Morphologic observations and measurement recordings were conducted under a light microscope on trophozoites obtained from the cultured isolates. Genomic sequences of the ITS, 18S ribosomal RNA (18S rRNA), Fe-hydrogenase, and RNA polymerase II largest subunit (Rpb1) regions were determined by direct sequencing, and phylogenetic analyses were conducted with previously published sequences of Trichomonas spp. All isolates were concluded as T. gypaetinii based on morphologic and molecular characterizations of the ITS and 18S rRNA genes. This is the first study to isolate T. gypaetinii from Haliaeetus eagles and further provide novel sequences of the Fe-hydrogenase and Rpb1 genes of T. gypaetinii. Both genomic regions also confirmed that T. gypaetinii belong to independent clusters from other Trichomonas spp.

Phylogeography of the dugong (Dugong dugon) based on historical samples identifies vulnerable Indian Ocean populations.

We investigated the phylogeography of the dugong (Dugong dugon) across its original range using museum material from 14 natural history museum and university collections. The mitochondrial DNA control region was successfully amplified from samples of bone or tooth powder from 162 individuals. These samples range from 1827 to 1996 and span the historical distribution range of the dugong. We were able to successfully amplify overlapping fragments of the D-loop region of the mitochondrial DNA (mtDNA) resulting in sequences of a 355 bp fragment for 162 individuals for the final analyses. This included a new sequence (189 bp) from a previously unidentified piece of skin of the extinct Steller’s sea cow (Hydrodamalis gigas), as an outgroup. The resulting dugong sequences match those from previous studies of dugongs from Australia and Indonesia, but revealed several new and divergent mtDNA lineages in the Indian Ocean. One mtDNA lineage includes most specimens from the Western Indian Ocean, with another distinct lineage isolated to nearby Madagascar and Comores. There is little geographic structuring detectable among other populations in the Western Indian Ocean and all populations from that region appear to have historically contained comparatively low levels of genetic diversity. The genetic diversity of several Indian Ocean samples collected after 1950 was lower than that of the samples collected earlier from similar locations, a result coincident with the anecdotal reductions in population size. The new lineages and potential loss of diversity highlight the particular conservation importance and vulnerability of dugong populations in the Western Indian Ocean.

Molecular phylogeny of the extinct Steller's sea cow and other Sirenia species based on their complete mitochondrial genomes

The Steller's sea cow – Hydrodamalis gigas (Dugongidae: Sirenia) – is an extinct herbivorous marine mammal which inhabited the North Pacific Ocean during the Pleistocene and Holocene. H. gigas was the largest member of the Sirenia order and disappeared in the middle of the 18th century. Here, we present the complete sequence of the mitochondrial genome of this extinct animal. The Steller's sea cow mitochondrial DNA (mtDNA) is 16,872 base pairs (bp) in length and contains a set of mitochondrial genes typical for mammals. Phylogenetic analysis based on complete mitochondrial genomes of the sirenian species allows accurate assessment of the degree of their mitogenomic diversification during millions of years of evolution.

Lead exposure in raptors from Japan and source identification using Pb stable isotope ratios

Lead (Pb) poisoning is widespread among raptors and water birds. In Japan, fragments of Pb ammunition are still found in endangered eagles although more than 10 years have passed since legislation regarding use of Pb ammunition was introduced. This study was performed to investigate Pb exposure in raptors from various locations in Japan. We measured hepatic and renal Pb concentrations and hepatic Pb isotope ratios of Steller's sea eagles (Haliaeetus pelagicus), white-tailed sea eagles (Haliaeetus albicilla), golden eagles (Aquila chrysaetos), and 13 other species (total 177 individuals) that were found dead, as well as blood samples from three eagles found in a weakened state during 1993–2015 from Hokkaido (northern part), Honshu (the main island), and Shikoku (a southern island) of Japan. In the present study in Hokkaido, one quarter of the sea eagles showed a high Pb concentration, suggesting exposure to abnormally high Pb levels and Pb poisoning. Pb isotope ratios indicated that endangered Steller's sea eagle and white-tailed sea eagle were poisoned by Pb ammunition that was used illegally in Hokkaido. In other areas of Japan, both surveillance and regulations were less extensive than in Hokkaido, but Pb poisoning in raptors was also noted. Therefore, Pb poisoning is still a serious problem in raptors in various areas of Japan due to accidental ingestion of materials containing Pb, especially Pb ammunition.

Inactivation of thermogenic UCP1 as a historical contingency in multiple placental mammal clades.

Mitochondrial uncoupling protein 1 (UCP1) is essential for nonshivering thermogenesis in brown adipose tissue and is widely accepted to have played a key thermoregulatory role in small-bodied and neonatal placental mammals that enabled the exploitation of cold environments. We map ucp1 sequences from 133 mammals onto a species tree constructed from a ~51-kb sequence alignment and show that inactivating mutations have occurred in at least 8 of the 18 traditional placental orders, thereby challenging the physiological importance of UCP1 across Placentalia. Selection and timetree analyses further reveal that ucp1 inactivations temporally correspond with strong secondary reductions in metabolic intensity in xenarthrans and pangolins, or in six other lineages coincided with a ~30 million-year episode of global cooling in the Paleogene that promoted sharp increases in body mass and cladogenesis evident in the fossil record. Our findings also demonstrate that members of various lineages (for example, cetaceans, horses, woolly mammoths, Steller's sea cows) evolved extreme cold hardiness in the absence of UCP1-mediated thermogenesis. Finally, we identify ucp1 inactivation as a historical contingency that is linked to the current low species diversity of clades lacking functional UCP1, thus providing the first evidence for species selection related to the presence or absence of a single gene product.

Serologic evidence of Brucella infection in pinnipeds along the coast of Hokkaido, the northernmost main island of Japan.

Brucella infection in Hokkaido was serologically surveyed in four species of pinnipeds inhabiting Cape Erimo during 2008-2013 and the Shiretoko Peninsula in 1999 by ELISA using Brucella abortus and B. canis as antigens. Anti-Brucella positive sera showed higher absorbance to B. abortus than B. canis in almost all samples. Anti-B. abortus antibodies were detected in serum samples from 24% (n = 55) of Western Pacific harbor seals (Phoca vitulina stejnegeri) in Cape Erimo and from 66% (n = 41) of spotted seals (P. largha), 15% (n = 20) of ribbon seals (Histriophoca fasciata) and 18% (n = 17) of Western Steller's sea lions (Eumetopias jubatus jubatus) in the Shiretoko Peninsula. Anti-Brucella antibodies were detected at higher absorbance in 1- to 4-year-old harbor seals than in the pups and mature animals, suggesting either that Brucella infection mainly occurs after weaning or that it is maternally transmitted to pups with premature or suppressed immunity. Anti-Brucella antibodies were detected in both immature and mature spotted seals and ribbon seals, with higher absorbance in the former. The antibodies were detected only in mature Western Steller's sea lions. Western blot analysis of the serum samples showed some differences in band appearances, namely discrete versus smeary, and in the number of bands, indicating that multiple different Brucella may be prevalent in pinnipeds in Hokkaido. Alternatively, the Brucella of pinnipeds may have some intra-species diversity.

Microsatellite Analysis for Identification of Individuals Using Bone from the Extinct Steller's Sea Cow (Hydrodamalis gigas).

Microsatellite DNA can provide more detailed population genetic information than mitochondrial DNA which is normally used to research ancient bone. The methods detailed in this chapter can be utilized for any type of bone. However, for this example, four microsatellite loci were isolated from Steller's sea cow (Hydrodamalis gigas) using published primers for manatee and dugong microsatellites. The primers DduC05 (Broderick et al., Mol Ecol Notes 6:1275-1277, 2007), Tmakb60, TmaSC5 (Pause et al., Mol Ecol Notes 6: 1073-1076, 2007), and TmaE11 (Garcia-Rodriguez et al., Mol Ecol 12:2161-2163, 2000) all successfully amplified microsatellites from H. gigas. The DNA samples were from bone collected on Bering or St. Lawrence Islands. DNA was analyzed using primers with the fluorescent label FAM-6. Sequenced alleles were then used to indicate a difference in the number of repeats and thus a difference in individuals. This is the first time that H. gigas microsatellite loci have been isolated. These techniques for ancient bone microsatellite analysis allow an estimate of population size for a newly discovered St. Lawrence Island sea cow population.

Correction to: Rewriting the history of an extinction-was a population of Steller's sea cows (Hydrodamalis gigas) at St Lawrence Island also driven to extinction?

The Kommandorskiye Islands population of Steller's sea cow (Hydrodamalis gigas) was extirpated ca 1768 CE. Until now, Steller's sea cow was thought to be restricted in historic times to Bering and ...

The dilemma of trade samples and the importance of museum vouchers—caveats from a study on the extinction of Steller's sea cow: a comment on Crerar et al. (2014)

Crerar et al. [[1][1]] recently argued that a population of Steller's sea cows ( Hydrodamalis gigas ) persisted on St Lawrence Island (SLI), Alaska, well into historical time. If true, then Steller's sea cows were hunted to extinction in multiple places at different times in the past millennium [[2

Serendipity in research--investigation into illegal wildlife trade discovers a new population of Steller's sea cows: a reply to Pyenson et al. (2016).

According to Stejneger [[1][1]], it is most likely that the last of the great northern sea cows went extinct around 1768. Many Steller's sea cow ( Hydrodamalis gigas ) bones have been located on the Commander and Aleutian Islands to date [[2][2],[3][3]]. However, no verified H. gigas bones have ever

Does the presence of food in the vicinity increase the collision risk with wind turbines for white-tailed and Steller's sea eagles?

Does the presence of food in the vicinity increase the collision risk with wind turbines for white-tailed and Steller's sea eagles?

Sea otters, kelp forests, and the extinction of Steller’s sea cow

The late Pleistocene extinction of so many large-bodied vertebrates has been variously attributed to two general causes: rapid climate change and the effects of humans as they spread from the Old World to previously uninhabited continents and islands. Many large-bodied vertebrates, especially large apex predators, maintain their associated ecosystems through top-down forcing processes, especially trophic cascades, and megaherbivores also exert an array of strong indirect effects on their communities. Thus, a third possibility for at least some of the Pleistocene extinctions is that they occurred through habitat changes resulting from the loss of these other keystone species. Here we explore the plausibility of this mechanism, using information on sea otters, kelp forests, and the recent extinction of Steller's sea cows from the Commander Islands. Large numbers of sea cows occurred in the Commander Islands at the time of their discovery by Europeans in 1741. Although extinction of these last remaining sea cows during early years of the Pacific maritime fur trade is widely thought to be a consequence of direct human overkill, we show that it is also a probable consequence of the loss of sea otters and the co-occurring loss of kelp, even if not a single sea cow had been killed directly by humans. This example supports the hypothesis that the directly caused extinctions of a few large vertebrates in the late Pleistocene may have resulted in the coextinction of numerous other species.

Toxic Identification and Evaluation of Androgen Receptor Antagonistic Activities in Acid-Treated Liver Extracts of High-Trophic Level Wild Animals from Japan.

Sulfuric acid-treated liver extracts of representative high-trophic level Japanese animals were analyzed by toxic identification and evaluation (TIE) with chemically activated luciferase expression (CALUX) and chemical analysis to elucidate androgen receptor (AR) antagonistic activities and potential contributions of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). The activities were detected in striped dolphins (n = 5), Stejneger's beaked whales (n = 6), golden eagle (n = 1), and Steller's sea eagle (n = 1) with CALUX-flutamide equivalents (FluEQs) as follow: 38 (20-52), 47 (21-96), 5.0, and 80 μg FluEQ/g-lipid, respectively. The AR antagonism was detected in limited number of specimens at lower levels for finless porpoise, raccoon dog, and common cormorant. Theoretical activities (Theo-FluEQs) were calculated using the concentration of OCPs and PCBs and their IC25-based relative potency (REP) values. These total contribution to CALUX-FluEQ was 126%, 84%, 53%, 55%, and 44% for striped dolphin, Steller's sea eagle, Stejneger's beaked whale, finless porpoise, and golden eagle, respectively, and the main contributor was p,p'-DDE. However, most of the activities for raccoon dog (7.6%) and common cormorant (17%) could not be explained by OCPs and PCBs. This suggests other unknown compounds could function as AR antagonists in these terrestrial species.

Rewriting the history of an extinction-was a population of Steller's sea cows (Hydrodamalis gigas) at St Lawrence Island also driven to extinction?

The Kommandorskiye Islands population of Steller's sea cow (Hydrodamalis gigas) was extirpated ca 1768 CE. Until now, Steller's sea cow was thought to be restricted in historic times to Bering and Copper Islands, Russia, with other records in the last millennium from the western Aleutian Islands. However, Steller's sea cow bone has been obtained by the authors from St Lawrence Island, Alaska, which is significantly further north. Bone identity was verified using analysis of mitochondrial DNA. The nitrogen-15 (δ(15)N)/carbon-13 (δ(13)C) values for bone samples from St Lawrence Island were significantly (p ≤ 0.05) different from Bering Island samples, indicating a second population. Bone samples were dated to between 1030 and 1150 BP (approx. 800-920 CE). The samples date from close to the beginning of the mediaeval warm period, which could indicate that the population at St Lawrence Island was driven to extinction by climate change. A warming of the climate in the area may have changed the availability of kelp; alternatively or in addition, the animals may have been driven to extinction by the expansion of the Inuit from the Bering Strait region, possibly due to opening waterways, maybe following bowhead whales (Balaena mysticetus), or searching for iron and copper. This study provides evidence for a previously unknown population of sea cows in the North Pacific within the past 1000 years and a second Steller's sea cow extirpation event in recent history.