Island Bay Research Articles

Abundance of anemone fishes in North Bay Island and mass culture of live food organisms for their larval rearing

Understanding the transect survey for abundance of anemone fishes and other living organisms is important to asses reef associated fish diversity in North Bay island. The percentage distribution of 10 different substratum from the disturbed, semi-disturbed and undisturbed areas was recorded during the survey in North Bay islands during November 2009 to April 2010. The survey observations reveal that the fishes were the dominant groups followed by mollusks, lobsters and octopus. There are 5 different anemone fishes were collected during the transect survey and their distribution is more in undisturbed area. We are standardizing the different mass culture techniques for production of phytoplankton and zooplankton for the nutritional source for the anemone fish larvae. Monitoring the water quality parameters and culture the phytoplankton and zooplankton used in different culture media with 2 adjustment studies like with and without salinity adjustment. The results of this experiment indicate that zooplankton was rich in protein and fat content and it will be used as high nutritional source for feeding fish larvae.

Abundance of anemone fishes in North Bay Island and mass culture of live food organisms for their larval rearing

Understanding the transect survey for abundance of anemone fishes and other living organisms is important to asses reef associated fish diversity in North Bay island. The percentage distribution of 10 different substratum from the disturbed, semi-disturbed and undisturbed areas was recorded during the survey in North Bay islands during November 2009 to April 2010. The survey observations reveal that the fishes were the dominant groups followed by mollusks, lobsters and octopus. There are 5 different anemone fishes were collected during the transect survey and their distribution is more in undisturbed area. We are standardizing the different mass culture techniques for production of phytoplankton and zooplankton for the nutritional source for the anemone fish larvae. Monitoring the water quality parameters and culture the phytoplankton and zooplankton used in different culture media with 2 adjustment studies like with and without salinity adjustment. The results of this experiment indicate that zooplankton was rich in protein and fat content and it will be used as high nutritional source for feeding fish larvae.

High calf mortality in bottlenose dolphins in the Bay of Islands, New Zealand–a local unit in decline

AbstractBottlenose dolphins (Tursiops truncatus) in the Bay of Islands, New Zealand, have been studied for almost two decades. Since 2003, fewer than 150 dolphins visited the bay during each season and the local unit has declined 7.5% annually from 1997 to 2006. The causes of decline are unclear but probably include mortality and emigration. Here, we used a long‐term database to estimate reproductive parameters of female bottlenose dolphins including recruitment rates. A total of 704 surveys were conducted in which 5,577 sightings of 408 individually identified dolphins were collected; of these 53 individuals were identified as reproductive females. The calving rate increased between periods (1997–1999 = 0.13, CL = 0.07–0.21; 2003–2005 = 0.25, CL = 0.16–0.35 calves/reproductive female/year). A 0.25 calving rate suggests that on average, a female gives birth only once every four years, which is consistent with the estimated calving interval (4.3 yr, SD = 1.45) but still is lower than values reported for other populations. Conversely, apparent mortality rates to age 1+ (range: 0.34–0.52) and 2+ (range: 0.15–0.59) were higher than values reported elsewhere. The high apparent calf mortality in conjunction with a decline in local abundance, highlight the vulnerability of bottlenose dolphins in the Bay of Islands. Long‐term studies are required to understand the causes of high calf mortality and the decline in local abundance. Meanwhile, management should focus on minimizing sources of anthropogenic disturbance and enforcing compliance with current legislation.

The first record of an association between a pontoniine shrimp (Crustacea: Decapoda: Palaemonidae: Pontoniinae) and a thalassematid spoon worm (Echiura: Thalassematidae), with the description of a new shrimp species.

A new pontoniine shrimp species, Eupontonia nudirostris sp. nov. (Crustacea: Decapoda: Palaemonidae: Pontoniinae), was found in association with the thalassematid spoon worm Listriolobus sp. (Echiura: Thalassematidae) in the mangrove littoral of Dam Bay of Tre Island, Nhatrang Bay, Vietnam. This is the first record of an association between symbiotic pontoniine shrimp and spoon worm as their host. The new shrimp species clearly differs from other representatives of the genus Eupontonia Bruce, 1971 by the unarmed rostrum with a blunt tip and the reduced antennal tooth on the carapace, which can be considered as an adaptation to symbiotic lifestyle inside cramped burrows of the host. A revised key to the genus Eupontonia Bruce, 1971 is presented.

Effects and risk evaluation of oil spillage in the sea areas of Changxing Island.

This paper evaluated the oil spillage risk in the waters near the island of Changxing in Dalian (China) based on the established risk assessment index. Four wind regimes (windless, northerly wind, westerly wind and southerly wind) were selected as weather conditions for the dynamic prediction of oil drift. If an oil spill occurs near the Koumen (a place near the island of Changxing), the forecast and evaluation are conducted based on a three-dimensional mathematical model of oil spillage, and the results obtained show the scope of the affected area when winds from various directions are applied. The oil spillage would, under various conditions, flow into the northern and western sea area of Changxing Island Bay, namely the Dalian harbor seal National Nature Reserve, and create adverse effects on the marine ecological environment. The rationality of combining the established oil spillage risk comprehensive index system with model prediction is further confirmed. Finally, preventive measures and quick fixes are presented in the case of accidental oil spillages. The most effective method to reduce environment risk is to adopt reasonable preventive measures and quick fixes.

Glacial retreat in the Amundsen Sea sector, West Antarctica – first cosmogenic evidence from central Pine Island Bay and the Kohler Range

The Amundsen Sea Embayment of West Antarctica hosts one of the most rapidly changing sectors of the West Antarctic Ice Sheet. With the fastest-flowing ice streams in Antarctica, the region around Pine Island Bay is characterized by rapid ice-sheet thinning and grounding-line retreat. Published surface-exposure data are limited to a few isolated nunataks making it difficult to assess the long-term deglacial history of the area. To address this, we correlate existing records of lateral ice-stream retreat from marine sediment cores with onshore glacial thinning in two key areas of eastern Marie Byrd Land: the Kohler Range and Pine Island Bay. Our 10Be surface-exposure ages are the first from the isolated Kohler Range and show that the nunataks there became ice-free between 8.6 and 12.6 ka. This implies a minimum long-term average thinning rate of 3.3 ± 0.3 cm/yr, which is one order of magnitude lower than recent rates based on satellite data. We also present pre- to early Holocene 10Be surface-exposure ages from two islands located approximately 80 km downstream of the Pine Island Glacier ice-shelf front to constrain the lateral deglacial history in the Pine Island Bay area. This study provides insight into the significance of local ice sheet variations and suggests that the post-LGM history in the Amundsen Sea sector was characterized by glacial thinning as well as lateral retreat in pre- to early Holocene times.

Future Antarctic bed topography and its implications for ice sheet dynamics

Abstract. The Antarctic bedrock is evolving as the solid Earth responds to the past and ongoing evolution of the ice sheet. A recently improved ice loading history suggests that the Antarctic Ice Sheet (AIS) has generally been losing its mass since the Last Glacial Maximum. In a sustained warming climate, the AIS is predicted to retreat at a greater pace, primarily via melting beneath the ice shelves. We employ the glacial isostatic adjustment (GIA) capability of the Ice Sheet System Model (ISSM) to combine these past and future ice loadings and provide the new solid Earth computations for the AIS. We find that past loading is relatively less important than future loading for the evolution of the future bed topography. Our computations predict that the West Antarctic Ice Sheet (WAIS) may uplift by a few meters and a few tens of meters at years AD 2100 and 2500, respectively, and that the East Antarctic Ice Sheet is likely to remain unchanged or subside minimally except around the Amery Ice Shelf. The Amundsen Sea Sector in particular is predicted to rise at the greatest rate; one hundred years of ice evolution in this region, for example, predicts that the coastline of Pine Island Bay will approach roughly 45 mm yr−1 in viscoelastic vertical motion. Of particular importance, we systematically demonstrate that the effect of a pervasive and large GIA uplift in the WAIS is generally associated with the flattening of reverse bed slope, reduction of local sea depth, and thus the extension of grounding line (GL) towards the continental shelf. Using the 3-D higher-order ice flow capability of ISSM, such a migration of GL is shown to inhibit the ice flow. This negative feedback between the ice sheet and the solid Earth may promote stability in marine portions of the ice sheet in the future.

Authigenic monazite and detrital zircon dating from the Proterozoic Rocky Cape Group, Tasmania: Links to the Belt-Purcell Supergroup, North America

The oldest known rocks in Tasmania occur in the Proterozoic Rocky Cape Group, a ∼10km thick quartzarenite-siltstone-pelite-dominated succession, previously constrained to have been deposited between 1450Ma and 750Ma. The Rocky Cape Group contains the enigmatic fossil Horodyskia (‘string of beads’) and has the potential to place Tasmania within supercontinent reconstructions. Detrital zircon and authigenic monazite grains dated via U–Pb laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) analysis yield a deposition window between c. 1450Ma (youngest zircon populations) and c. 1330Ma (oldest authigenic monazite population) for the ∼9km thick lower-middle units (Pedder River Siltstone, Lagoon River Quartzite, Balfour Subgroup which hosts Horodyskia, Detention Subgroup). The upper units (∼1km) include the Irby Siltstone, which is younger than c. 1310Ma; this unit is likely separated from both the lower-middle units and the overlying c. <1010Ma Jacob Quartzite by disconformities. The lower-middle Rocky Cape Group is dominated by detrital zircon populations between 1600 and 1900Ma, with subordinate populations at c. 1450Ma and a spread of older grains mostly between 2300 and 2900Ma. The overlying Irby Siltstone has a bimodal detrital zircon distribution with a dominant peak at c. 1340Ma and a secondary peak at c. 1720Ma; no >1900Ma grains were identified.Authigenic monazite age distributions are complex, with multiple age domains within most samples. The common Pb corrected 206U/238Pb ages, defined by oldest grains in each sample, identify three statistically significant groups: (1) 1358–1292Ma (inclusive of two sigma errors) (Lagoon River Quartzite and Pedder River Siltstone), (2) 1283–1239Ma (Cowrie Siltstone and Balfour Subgroup), and (3) 1085±9Ma (Detention Subgroup). We suggest monazite was precipitated during episodic fluid flow events at these three stages in various parts of the basin. The original source for REE-bearing fluids could be detrital monazite, which is rarely preserved, and/or organic matter from the interbedded carbonaceous shales.The Rocky Cape Group has a shared provenance with the higher-grade metasediments (Surprise Bay and Fraser formations) of nearby King Island; the newly derived depositional ages also overlap and support the correlation of these rock associations. On the basis of current datasets, there are no obvious correlations that can be made with Mesoproterozoic basins preserved in mainland Australia. Instead, an overlap in the timing of deposition, similarities in detrital zircon signatures and analogous depositional environment suggests the c. 1.45–1.37Ga upper Belt-Purcell Supergroup (Missoula and Lemhi groups) of western North America constitutes a plausible correlation with the Tasmanian Mesoproterozoic succession. If the (unexposed) Palaeoproterozoic basement of Tasmania correlates with the Transantarctic Mountains region of East Antarctica as previously proposed, we suggest that the overlying Mesoproterozoic sequences were deposited during rifting of the supercontinent Nuna, between proto-Australia (including the Mawson craton of Antarctica) and Laurentia as predicted by the most recent palaeogeographic reconstructions. Both the Tasmanian and western Laurentian packages were affected by episodic post-depositional fluid flow events between c. 1.35 and 1.05Ga, possible thermotectonic imprints of the subsequent assembly of Rodinia.

Northern New Zealand rhodoliths: assessing faunal and floral diversity in physically contrasting beds

Rhodolith beds are recognised internationally as unique ecosystems, harbouring a high diversity and abundance of marine biota. Beds typically occur in environments of moderate exposure and coarse sandy sediments, in which individual rhodoliths are not moved away from the beds, and do not get buried by fine sediments. For the first time in New Zealand, we have physically and biologically characterised selected rhodolith beds in order to document the marine biota within and beneath them. Three beds at two locations in the Bay of Islands, northern New Zealand, were sampled in February and September 2010; two beds were located in a typical rhodolith habitat (a sandy channel), and one in an atypical habitat (a muddy bay). In each bed, rhodolith species and abundance were analysed along with environmental characteristics (sediment granulometry, light environment, temperature, current speed and direction). Characterisation of biological diversity associated with the rhodolith beds included assessment of macroalgae, invertebrates (surface and subsurface) and fish. Sampling within the beds produced a total of 238 taxa: 197 invertebrates, 37 algal and four fish taxa, indicating that a high diversity of biota occur within these northern New Zealand rhodolith beds. We found significant differences in the abundance, taxon richness, and community structure of the biota among rhodolith beds, and surprisingly, the highest abundance and taxon richness occurred in a bed in a highly sedimented environment. In addition, two adjacent and physically similar beds were significantly different from each other in terms of community structure. This finding points to the importance of sampling individual rhodolith beds and suggests that it would be risky to extrapolate findings to other beds, even those in close proximity.

Changes in habitat use patterns by bottlenose dolphins over a 10‐year period render static management boundaries ineffective

ABSTRACT Bottlenose dolphins (Tursiops truncatus) in northern New Zealand range widely and their coastal distribution increases their risk of exposure to a variety of threats. Marine protected areas (MPAs) are increasingly used to protect species but there is a paucity of studies examining their efficacy. In the Bay of Islands, New Zealand (35°14'S, 174°06'E), dolphin distribution and habitat use patterns were examined between two time periods: 1996–2000 and 2007–2010. In addition, dolphin use of tourism exclusion zones designed to protect the dolphins were assessed. Spatial distribution was analysed using kernel densities and Mantel tests. Broad‐scale distribution patterns remained constant between the two periods but fine‐scale dolphin distribution patterns shifted considerably. The exclusion zones that were established based on results from the 1996–2000 study were rarely used in 2007–2010, and therefore no longer provided dolphins protection from tourism. This research demonstrates the plasticity in dolphin habitat use patterns through time and the importance of re‐evaluating the efficacy of static protected areas, especially for wide‐ranging species. Copyright © 2014 John Wiley &amp; Sons, Ltd.

A new species of crinoid-associated Periclimenes from Honduras (Crustacea: Decapoda: Palaemonidae).

A new species of crinoid associated Periclimenes, P. rincewindi sp. nov. is described from the Bay Islands (Honduras) in the Caribbean. The species associates with the swimming crinoid, Analcidometra armata and displays a unique colour pattern. Morphologically, the new species is closely related to the other known crinoid associates in the Caribbean, specifically Periclimenes crinoidalis, from which it can be distinguished by a suite of relatively minor morphological features.

Epiphytic dinoflagellates in sub-tropical New Zealand, in particular the genus Coolia Meunier

Macroalgae growing in New Zealand's sub-tropical waters were sampled for epiphytic microalgae, in particular dinoflagellates. Four new Coolia isolates collected from sites throughout Northland in January/February 2013 were all identified as C. malayensis as determined by large subunit ribosomal DNA (LSU rDNA) sequence analysis and scanning electron microscopy. C. malayensis, a common dinoflagellate species in New Zealand, was previously reported as C. monotis and isolates held in the Cawthron Institute Culture Collection of Microalgae have now been reclassified based on the DNA sequence data. Toxicity studies of the New Zealand C. malayensis isolates (as determined by intraperitoneal (i.p.) injection of mice) resulted in an LD50 of 80.0mg/kg for isolate NLD 12 (95% CI: 63.8–101.0mg/kg) compared to a Malaysian isolate which exhibited low toxicity, with transient effects at 900mg/kg, but which resulted in the enlargement of the test animal's spleen. Ostreopsis siamensis, a common epiphytic bloom former in northern New Zealand, was found in association with Coolia at sites across Northland. Densest cell concentrations were collected from macroalgae throughout the Bay of Islands. Four new isolates of O. siamensis all produced palytoxin-like compounds (LC–MS analysis). Also isolated from Northland macroalgae were Amphidinium thermaeum (non-toxic by i.p. injection of mice) and Gambierdiscus cf. yasumotoi, with the latter producing a putative maitotoxin analogue (MTX-3) as determined by LC–MS.

Surnames in Honduras: A Study of the Population of Honduras through Isonymy

In this work, we investigated surname distribution in 4,348,021 Honduran electors with the aim of detecting population structure through the study of isonymy in three administrative levels: the whole nation, the 18 departments, and the 298 municipalities. For each administrative level, we studied the surname effective number, α, the total inbreeding, FIT , the random inbreeding, FST , and the local inbreeding, FIS . Principal components analysis, multidimensional scaling, and cluster analysis were performed on Lasker's distance matrix to detect the direction of surname diffusion and for a graphic representation of the surname relationship between different locations. The values of FIT , FST , and FIS display a variation of random inbreeding between the administrative levels in the Honduras population, which is attributed to the "Prefecture effect." Multivariate analyses of department data identified two main clusters, one south-western and the second north-eastern, with the Bay Islands and the eastern Gracias a Dios out of the main clusters. The results suggest that currently the population structure of this country is the result of the joint action of short-range directional migration and drift, with drift dominating over migration, and that population diffusion may have taken place mainly in the NW-SE direction.

Export and circulation of ice cavity water in Pine Island Bay, West Antarctica

Large sectors of the Antarctic ice sheet are vulnerable to increases in melting at the bases of fringing ice shelves, with melt rates depending on ocean temperatures and circulations in the sub-ice cavities. Here we analyze an oceanographic data set obtained in austral summer 2009 in Pine Island Bay, which is bounded in the east by the calving front of the Amundsen Sea's fast-moving Pine Island Ice Shelf. The upper-ocean velocity field in the ice-free bay was dominated by a 700 m deep and 50 km wide gyre circulating 1.5 Sv of water clockwise around the bay. Ice cavity water was observed in a surface-intensified and southward-intensified boundary current along the ice front, and in a small ice cove at the end of the southern shear margin of the ice shelf. Repeat measurements in the cove reveal persistent cavity water export of ≈ 0.25 Sv during 10 days of sampling. Vertical velocities in the cove above the ice draft were dominated by buoyancy-frequency oscillations with amplitudes of several cm/s but without significant net upwelling. In combination with the seawater properties, this observation indicates that much of the upwelling occurs within fractured ice near the cove, potentially contributing to weakening the ice shelf shear margin.

Macroalgal Diversity Associated with Rhodolith Beds in Northern New Zealand

The macroalgal flora associated with rhodolith beds in the Bay of Islands, northeastern North Island, was investigated as part of the first detailed study of subtidal rhodoliths in New Zealand. The rhodolith beds differed in their physical characteristics and in the dominant rhodolith-forming species present, one bed with clear water and predominantly Lithothamnion crispatum rhodoliths, and the other bed with turbid water, and Sporolithon durum rhodoliths covered by fine sediments. One hundred and three taxa were identified (12 green, 24 brown and 67 red algae), with similar numbers of taxa found in the two seasons sampled. The floral composition at the two beds differed significantly. The flora included range extensions for species previously reported within New Zealand (e.g. Cutleria multifida), new records for the New Zealand region (at family, genus and species levels — e.g. Dumontiaceae, Cutleria, Dictyota, Peyssonnelia spp), and new discoveries (e.g. Halymenia sp., Grateloupia sp., Tsengia sp.). Two species with a partially prostrate growth habit, Caulerpa flexilis and Chondracanthus chapmanii, were present in both beds consolidating rhodoliths and shell debris.

Tropical Pacific Influence on the Source and Transport of Marine Aerosols to West Antarctica*

Abstract The climate of West Antarctica is strongly influenced by remote forcing from the tropical Pacific. For example, recent surface warming over West Antarctica reflects atmospheric circulation changes over the Amundsen Sea, driven by an atmospheric Rossby wave response to tropical sea surface temperature (SST) anomalies. Here, it is demonstrated that tropical Pacific SST anomalies also influence the source and transport of marine-derived aerosols to the West Antarctic Ice Sheet. Using records from four firn cores collected along the Amundsen coast of West Antarctica, the relationship between sea ice–modulated chemical species and large-scale atmospheric variability in the tropical Pacific from 1979 to 2010 is investigated. Significant correlations are found between marine biogenic aerosols and sea salts, and SST and sea level pressure in the tropical Pacific. In particular, La Niña–like conditions generate an atmospheric Rossby wave response that influences atmospheric circulation over Pine Island Bay. Seasonal regression of atmospheric fields on methanesulfonic acid (MSA) reveals a reduction in onshore wind velocities in summer at Pine Island Bay, consistent with enhanced katabatic flow, polynya opening, and coastal dimethyl sulfide production. Seasonal regression of atmospheric fields on chloride (Cl−) reveals an intensification in onshore wind velocities in winter, consistent with sea salt transport from offshore source regions. Both the source and transport of marine aerosols to West Antarctica are found to be modulated by similar atmospheric dynamics in response to remote forcing. Finally, the regional ice-core array suggests that there is both a temporally and a spatially varying response to remote tropical forcing.

Future Antarctic bed topography and its implications for ice sheet dynamics

<strong class="journal-contentHeaderColor">Abstract.</strong> The Antarctic bedrock is evolving as the solid Earth responds to the past and ongoing evolution of the ice sheet. A recently improved ice loading history suggests that the Antarctic Ice Sheet (AIS) has generally been losing its mass since the Last Glacial Maximum. In a sustained warming climate, the AIS is predicted to retreat at a greater pace, primarily via melting beneath the ice shelves. We employ the glacial isostatic adjustment (GIA) capability of the Ice Sheet System Model (ISSM) to combine these past and future ice loadings and provide the new solid Earth computations for the AIS. We find that past loading is relatively less important than future loading for the evolution of the future bed topography. Our computations predict that the West Antarctic Ice Sheet (WAIS) may uplift by a few meters and a few tens of meters at years AD 2100 and 2500, respectively, and that the East Antarctic Ice Sheet is likely to remain unchanged or subside minimally except around the Amery Ice Shelf. The Amundsen Sea Sector in particular is predicted to rise at the greatest rate; one hundred years of ice evolution in this region, for example, predicts that the coastline of Pine Island Bay will approach roughly 45 mm yr^&minus;1 in viscoelastic vertical motion. Of particular importance, we systematically demonstrate that the effect of a pervasive and large GIA uplift in the WAIS is generally associated with the flattening of reverse bed slope, reduction of local sea depth, and thus the extension of grounding line (GL) towards the continental shelf. Using the 3-D higher-order ice flow capability of ISSM, such a migration of GL is shown to inhibit the ice flow. This negative feedback between the ice sheet and the solid Earth may promote stability in marine portions of the ice sheet in the future.

Diverse coral communities in naturally acidified waters of a Western Pacific reef

AbstractAnthropogenic carbon dioxide emissions are acidifying the oceans, reducing the concentration of carbonate ions ([CO32−]) that calcifying organisms need to build and cement coral reefs. To date, studies of a handful of naturally acidified reef systems reveal depauperate communities, sometimes with reduced coral cover and calcification rates, consistent with results of laboratory‐based studies. Here we report the existence of highly diverse, coral‐dominated reef communities under chronically low pH and aragonite saturation state (Ωar). Biological and hydrographic processes change the chemistry of the seawater moving across the barrier reefs and into Palau's Rock Island bays, where levels of acidification approach those projected for the western tropical Pacific open ocean by 2100. Nevertheless, coral diversity, cover, and calcification rates are maintained across this natural acidification gradient. Identifying the combination of biological and environmental factors that enable these communities to persist could provide important insights into the future of coral reefs under anthropogenic acidification.

Screening and Characterization of Several 2,2-Dicholoropropionic Acid–Degrading Bacteria Isolated from Marine Sediment of Danga Bay and East Coast of Singapore Island

ABSTRACT Industries and agriculture activities extensively utilize halogenated compounds. These compounds were found to be toxic and pollute the environment. Thus, many studies have been done on microbial degradation of these chemicals. In this study, an attempt was made to isolate bacterial strains EK1–EK5 from marine sediments collected at Danga Bay and east coast of Singapore island. The 16S rRNA analysis suggested that the isolated bacteria had more than 96% sequence identity to the sequence in the database; therefore, they were designated as Bacillus sp., Rhodococcus sp., Lysinibacillus sp., Microbacterium sp., and Aminobacter sp. The results of molecular analysis were supported by biochemical and microscopic examinations. Bacterial isolates were able to grow slowly in minimal medium containing only 2,2-dichloropropionate as the sole carbon source. The cellular doubling times were 39.60 ± 0.1, 36.60 ± 0.2, 30.71 ± 0.1, 41.23 ± 0.1, and 36.70 ± 0.3 h for EK1, EK2, EK3, EK4, and EK5, respectively. In the future, it will be important to further investigate the presence of the dehalogenase gene in their genomic DNA for further characterization.

Genetic structure of northern red-backed vole (Myodes (=Clethrionomys) rutilus Pallas, 1779) populations of the northern priokhotye determined by sequence variation of the mtDNA cytochrome B gene

The purpose of this study was to investigate the genetic structure of coastal populations of the northern red-backed vole, Myodes (=Clethrionomys) rutilus, in northern Priokhotye on the basis of variation of a partial mtDNA cytb sequence. For the first time, the nucleotide and haplotype diversity of cytb sequences was described in M. rutilus from the islands of Matykil, Nedorazumeniya, Spafareva, and Talan (northern part of the Sea of Okhotsk), as well as from the Koni Peninsula, the vicinity of Magadan, and the Yama River basin, and the genetic structure of these populations was determined. Island populations of M. rutilus were found to have unique gene pools comprising two or three haplotypes each. In northern red-backed voles of the mainland coast of the Sea of Okhotsk, cytb sequences were highly polymorphic. Presumably, northern red-backed voles of the northern Priokhotye form a continuous coastal population. The results of genetic analysis suggest that M. rutilus populations of Tauisk Bay islands and the mainland coast of the Sea of Okhotsk belong to the same maternal strain, whereas northern red-backed voles from the island of Matykil in the Shelikhov Gulf represent a different genetic lineage.