920 resultados para Aleutian Islands Alaska
Resumo:
Owing to their high vulnerability and low adaptive capacity, Caribbean islands have legitimate concerns about their future, based on observational records, experience with current patterns and consequences of climate variability, and climate model projections. Although emitting less than 1% of global greenhouse gases, islands from the region have already perceived a need to reallocate scarce resources away from economic development and poverty reduction, and towards the implementation of strategies to adapt to the growing threats posed by global warming (Nurse and Moore, 2005). The objectives of this Report are to conduct economic analyses of the projected impacts of climate change to 2050, within the context of the IPCC A2 and B2 scenarios, on the coastal and marine resources of the British Virgin Islands (BVI). The Report presents a valuation of coastal and marine services; quantitative and qualitative estimates of climate change impacts on the coastal zone; and recommendations of possible adaptation strategies and costs and benefits of adaptation. A multi-pronged approach is employed in valuing the marine and coastal sector. Direct use and indirect use values are estimated. The amount of economic activity an ecosystem service generates in the local economy underpins estimation of direct use values. Tourism and fisheries are valued using the framework developed by the World Resources Institute. Biodiversity is valued in terms of the ecological functions it provides, such as climate regulation, shoreline protection, water supply erosion control and sediment retention, and biological control, among others. Estimates of future losses to the coastal zone from climate change are determined by considering: (1) the effect of sea level rise on coastal lands; and (2) the effect of a rise in sea surface temperature (SST) on coastal waters. Discount rates of 1%, 2% and 4% are employed to analyse all loss estimates in present value terms. The overall value for the coastal and marine sector is USD $1,606 million (mn). This is almost 2% larger than BVI’s 2008 GDP. Tourism and recreation comprise almost two-thirds of the value of the sector. By 2100, the effects of climate change on coastal lands are projected to be $3,988.6 mn, and $2,832.9 mn under the A2 and B2 scenarios respectively. In present value terms, if A2 occurs, losses range from $108.1-$1,596.8 mn and if B2 occurs, losses range from $74.1-$1,094.1 mn, depending on the discount rate used. Estimated costs of a rise in SST in 2050 indicate that they vary between $1,178.0 and $1,884.8 mn. Assuming a discount rate of 4%, losses range from $226.6 mn for the B2 scenario to $363.0 mn for the A2 scenario. If a discount rate of 1% is assumed, estimated losses are much greater, ranging from $775.6-$1,241.0 mn. Factoring in projected climate change impacts, the net value of the coastal and marine sector suggests that the costs of climate change significantly reduce the value of the sector, particularly under the A2 and B2 climate change scenarios for discount rates of 1% and 2%. In contrast, the sector has a large, positive, though declining trajectory, for all years when a 4% discount rate is employed. Since the BVI emits minimal greenhouse gases, but will be greatly affected by climate change, the report focuses on adaptation as opposed to mitigation strategies. The options shortlisted are: (1) enhancing monitoring of all coastal waters to provide early warning alerts of bleaching and other marine events; (2) introducing artificial reefs or fish-aggregating devices; (3) introducing alternative tourist attractions; (4) providing retraining for displaced tourism workers; and (5) revising policies related to financing national tourism offices to accommodate the new climatic realities. All adaptation options considered are quite justifiable in national terms; each had benefit-cost ratios greater than 1.
Resumo:
This study aimed to describe the population structure of the Amazon shrimp Macrobrachium amazonicum, as well as their relative growth between the length of the cephalothorax and the total length, and between the length of the cephalothorax and the total mass of shrimps of a fluvial-estuarine plain in the State of Pará. Shrimps were sampled monthly from August 2006 to July 2007, using trawl nets, taking three replicates at each site (Arapiranga and Mosqueiro) per month, totaling 72 replicates. We caught 5,510 specimens, being 90.90% from Arapiranga Island and 9.1% from Mosqueiro Island. The highest densities occurred in July (1.33 individuals/m2), at the beginning of the dry season and in December (1.66 individuals/m2), at the beginning of the rainy season. The morphometric analysis for separate and grouped sexes resulted in negative and positive allometric growth. Ovigerous females were observed in all months, indicating continuous reproduction and the majority (67.81%) was caught during the less rainy season. The abundance and continuous reproduction of M. amazonicum show that this estuary offers conditions for the proper development of this population.
Resumo:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Resumo:
The use of gastropod shells by hermit crabs is determined by the availability of shells in the environment or through selection for size and volume. This study analyzed patterns in the use of shells by Dardanus insignis (Saussure, 1858). From January 1998 to December 1999, 386 individuals were collected from two islands at Ubatuba, Sao Paulo. The crabs were measured for cephalothoracic shield length (CSL) and wet weight (CWW). The gastropod shells occupied by hermit crabs were identified, and the shell aperture width (SAW), dry weight (SDW) and internal volume (STY) were measured. The relationships between the dimensions of the gastropod shell and the hermit crabs were evaluated by linear regression analysis. Among the 11 species of gastropod shells used by D. insignis, the most often used was Olivancillaria urceus (31%), followed by Strombus pugilis (22%) and Siratus tenuivaricosus (18%). The shell of O. urceus was used most probably due to its high availability on Couves and Mar Virado islands. The most significant biometric parameter was shell aperture width (F=18.231; p<0.0001), highlighting the importance of this variable for the shell choice by D. insignis at both sites.
Resumo:
Fifty-one slimy sea plumes (Pseudopterogorgia americana Gmelin, 1791) were sampled for caridean shrimps at Guana Island, British Virgin Islands, during one week in July 1992. Sam- pling depth ranged from 3-22 m. Nine species were collected: Hippolyte nicholsoni Chace, 1972; Latreutes sp.; Neopontonides chacei Heard, 1986; Perclimenes cf. patae Heard and Spotte, 1991; Periclimenes cf. pauper Holthuis, 1951; Periclimenes sp.; Pseudocoutierea antillensis Chace, 1972; Tozeuma cf. cornutum Milne Edwards, 1881; and Trachycaris rugosa (Bate, 1888). A total of 1,418 specimens (including fragments) was obtained. The number of shrimp species per gorgonian ranged from 1-5; one gorgonian harbored 156 shrimps. The two predominant species, N. chacei and H. nicholsoni, occupy different mean depths (12.6 and 8.2 m, respectively). Sexual dimorphism assessed with Mann-Whitney U-tests was not apparent in the specimens of N. chacei (P > 0.05), but females of H. nicholsoni were significantly larger than males (P < 0.001). Minimum carapace length (CL, the tip of the rostrum to the posterior dorsal margin of the carapace) at which male N. chacei acquire a single appendix masculina spine is 1.25 mm; male H. nicholsoni can acquire a single spine at 0.9 mm CL. Histological sections of male N. chacei showed that shrimp with 0 or 1 spine are least likely to be mature. Female N. chacei can become ovigerous at 1.9 mm CL and female H. nicholsoni at 1.2 mm CL. The taxonomic status of 5 of the 9 species collected is uncertain.
Resumo:
North Pacific right whales (Eubalaena japonica) were extensively exploited in the 19th century, and their recovery was further retarded (severely so in the eastern population) by illegal Soviet catches in the 20th century, primarily in the 1960s. Monthly plots of right whale sightings and catches from both the 19th and 20th centuries are provided, using data summarized by Scarff (1991, from the whale charts of Matthew Fontaine Maury) and Brownell et al. (2001), respectively. Right whales had an extensive offshore distribution in the 19th century, and were common in areas (such as the Gulf of Alaska and Sea of Japan) where few or no right whales occur today. Seasonal movements of right whales are apparent in the data, although to some extent these reflect survey and whaling effort. That said, these seasonal movements indicate a general northward migration in spring from lower latitudes, and major concentrations above 40°N in summer. Sightings diminished and occurred further south in autumn, and few animals were recorded anywhere in winter. These north-south migratory movements support the hypothesis of two largely discrete populations of right whales in the eastern and western North Pacific. Overall, these analyses confirm that the size and range of the right whale population is now considerably diminished in the North Pacific relative to the situation during the peak period of whaling for this species in the 19th century. For management purposes, new surveys are urgently required to establish the present distribution of this species; existing data suggest that the Bering Sea, the Gulf of Alaska, the Okhotsk Sea, the Kuril Islands and the coast of Kamchatka are the areas with the greatest likelihood of finding right whales today.
Resumo:
Trichinosis in the arctic regions of the world has received considerable attention during recent years, particularly since the work of Roth (1948) in Greenland. In Connell's (1949) review of arctic trichinosis some Alaskan and Canadian records were included but, until now, little has been known of the status of the disease in Alaska. Information available at the present time indicates that the incidence of trichinosis is high in circumpolar carnivores and that marine mammals have a definite place in its epizootiology. Present knowledge cannot explain the survival of trichinosis in marine mammal populations, but it is evident that they may serve as important sources of human infection. Up to the present time the following mammals from Alaska have been found to be infected: From the arctic coast-polar bear, Thalarctas maritimus; arctic fox, Alapex lagapus irmuitus; red fox, Vulpes fulva alascemis; white whale, Delphinapterus leucas; Eskimo dog. From south of the Brooks Range--brown and grizzly bears, Ursus spp.; wolf, Canis lupus ssp.; wolverine. Gula l. luscus. At the time of writing, nearly ail species of land carnivores in Alaska have been examined as well as many other mammalian species less likely to be infected, including various rodents, shrews, and others.
Resumo:
Covers the physical attributes (physiography, climate and vegetation) of the Brooks Range, Alaska, as well as the Numamuit Eskimo people who lived there in the 1940s and before (including information about their livelihood, history, dwellings, clothing, food, transportation and hunting implements), and includes a list and description of the mammals that lived there (including shrews, grizzly bears, foxes, wolves, martens, ermines, weasels, minks, wolverines, otters, lynxes, hares, marmots, ground squirrels, red squirrels, lemmings, voles, beavers, porcupines, moose, caribou and sheep).
Resumo:
The abundance of harbor seals (Phoca vitulina richardii) has declined in recent decades at several Alaska locations. The causes of these declines are unknown, but there is concern about the status of the populations, especially in the Gulf of Alaska. To assess the status of harbor seals in the Gulf of Alaska, we conducted aerial surveys of seals on their haul-out sites in August-September 1996. Many factors influence the propensity of seals to haul out, including tides, weather, time of day, and time of year. Because these “covariates” cannot simultaneously be controlled through survey design, we used a regression model to adjust the counts to an estimate of the number of seals that would have been ashore during a hypothetical survey conducted under ideal conditions for hauling out. The regression, a generalized additive model, not only provided an adjustment for the covariates, but also confirmed the nature and shape of the covariate effects on haul-out behavior. The number of seals hauled out was greatest at the beginning of the surveys (mid-August). There was a broad daily peak from about 1100-1400 local solar time. The greatest numbers were hauled out at low tide on terrestrial sites. Tidal state made little difference in the numbers hauled out on glacial ice, where the area available to seals did not fluctuate with the tide. Adjusting the survey counts to the ideal state for each covariate produced an estimate of 30,035 seals, about 1.8 times the total of the unadjusted counts (16,355 seals). To the adjusted count, we applied a correction factor of 1.198 from a separate study of two haul-out sites elsewhere in Alaska, to produce a total abundance estimate of 35,981 (SE 1,833). This estimate accounts both for the effect of covariates on survey counts and for the proportion of seals that remained in the water even under ideal conditions for hauling out.
Resumo:
The hunting behavior of leopard seals Hydrurga leptonyx was monitored opportunistically at Seal Island, South Shetland Islands, during the austral summers from 1986/87 to 1994/95. Leopard seals used several methods to catch Antarctic fur seal pups Arctocephalus gazella and chinstrap penguins Pygoscelis antarctica, and individuals showed different hunting styles and hunting success. One to two leopard seals per year were responsible for an average of 60% of observed captures of fur seal pups. Leopard seals preyed on penguins throughout the summer, but preyed on fur seal pups only between late December and mid-February. Hunting behavior differed significantly between different locations on the island; fur seals were hunted only at one colony, and penguins were hunted in several areas. The relative abundance of prey types, size of prey in relation to predator, and specialization of individual leopard seals to hunt fur seal prey probably influence individual prey preferences among leopard seals. On five occasions, two leopard seals were seen together on Seal Island. Possible interpretations of the relationship between the interacting leopard seals included a mother-offspring relationship, a consorting male-female pair, and an adult leopard seal followed by an unrelated juvenile. In two incidents at Seal Island, two leopard seals were observed interacting while hunting: one seal captured fur seal pups and appeared to release them to the other seal. Observations of leopard seals interacting during hunting sessions were difficult to confirm as co-operative hunting, but they strongly implied that the two seals were not agonistic toward one another. The hunting success of individual leopard seals pursuing penguins or fur seals is probably high enough for co-operative hunting not to become a common hunting strategy; however, it may occur infrequently when it increases the hunting productivity of the seals.
Resumo:
Aim To assess the distribution, group size, seasonal occurrence and annual trends of cetaceans. Location The study area included all major inland waters of Southeast Alaska. Methods Between 1991 and 2007, cetacean surveys were conducted by observers who kept a constant watch when the vessel was underway and recorded all cetaceans encountered. For each species, we examined distributional patterns, group size, seasonal occurrence and annual trends. Analysis of variance (anova F) was used to test for differences in group sizes between multiple means, and Student’s t-test was used to detect differences between pairwise means. Cetacean seasonal occurrence and annual trends were investigated using a generalized linear model framework. Results Humpback whales (Megaptera novaeangliae) were seen throughout the region, with numbers lowest in spring and highest in the fall. Fin whale (Balaenoptera physalus) and minke whale (Balaenoptera acutorostrata) distributions were more restricted than that reported for humpback whales, and the low number of sightings precluded evaluating seasonal trends. Three killer whale (Orcinus orca) eco-types were documented with distributions occurring throughout inland waters. Seasonal patterns were not detected or could not be evaluated for resident and offshore killer whales, respectively; however, the transient eco-type was more abundant in the summer. Dall’s porpoise (Phocoenoides dalli) were distributed throughout the region, with more sightings in spring and summer than in fall. Harbour porpoise (Phocoena phocoena) distribution was clumped, with concentrations occurring in the Icy Strait/Glacier Bay and Wrangell areas and with no evidence of seasonality. Pacific white-sided dolphins (Lagenorhynchus obliquidens) were observed only occasionally, with more sightings in the spring. For most species, group size varied on both an annual and seasonal basis. Main conclusions Seven cetacean species occupy the inland waters of Southeast Alaska, with distribution, group size, seasonal occurrence and annual trends varying by species. Future studies that compare spatial and temporal patterns with other features (e.g. oceanography, prey resources) may help in identifying the key factors that support the high density and biodiversity of cetaceans found in this region. An increased understanding of the region’s marine ecology is an essential step towards ensuring the long-term conservation of cetaceans in Southeast Alaska.
Resumo:
Beginning in the late 1980s, large groups of previously unidentified killer whales (Orcinus orca) were sighted off the west coast of Vancouver Island and in the Queen Charlotte Islands, British Columbia. Scientists working in this region produced two killer whale photo-identification catalogues that included both transient (mammal-eating) whales and 65 individual whales that investigators believed represented a distinct killer whale community (Ford et al. 1992, Heise et al. 1993). It was thought that these killer whales maintained a generally offshore distribution and were provisionally termed “offshores”; a term that has since been used as a population identifier for the eastern temperate North Pacific offshore killer whale population. Then in September 1992, 75 unidentified whales entered the Strait of Juan de Fuca just south and east of Victoria, British Columbia (Walters et al. 1992). Although most of these whales had not been seen before, two were matched to killer whales in the Queen Charlotte photo-identification catalogue (Ford et al. 1992, Heise et al. 1993) and were thus listed as “offshore” killer whales. During a similar time period, other large groups of killer whales, previously unidentified, were also being sighted off Alaska and California (Dahlheim et al. 1997; Nancy Black and Alisa Schulman- Janiger, unpublished data, respectively).
Resumo:
Killer whale predation on belugas in Cook Inlet, Alaska, has become a concern since the decline of these belugas was documented during the 1990s. Accordingly, killer whale sightings were compiled from systematic surveys, observer databases, and anecdotal accounts. Killer whales have been relatively common in lower Cook Inlet (at least 100 sightings from 1975 to 2002), but in the upper Inlet, north of Kalgin Island, sightings were infrequent (18 in 27 yr), especially prior to the 1990s. Beach cast beluga carcasses with teeth marks and missing flesh also provided evidence of killer whale predation. Most observed killer whale/beluga interactions were in the upper Inlet. During 11 of 15 observed interactions, belugas were obviously injured or killed, either through direct attacks or indirectly as a result of stranding. Assuming at least one beluga mortality occurred during the other four encounters, we can account for 21 belugas killed between 1985 and 2002. This would suggest a minimum estimate of roughly l/yr and does not include at least three instances where beluga calves accompanied an adult that was attacked.
Resumo:
Between 1991 and 1993, Alaska harbor porpoise (Phocoena phocoena) abundance was investigated during aerial surveys throughout much of the coastal and offshore waters from Bristol Bay in the eastern Bering Sea to Dixon Entrance in Southeast Alaska. Line-transect methodology was used, and only those observations made during optimal conditions were analyzed. Survey data indicated densities of 4.48 groups/100 km2, or approximately 3,531 harbor porpoises (95% C.I. 2,206-5,651) in Bristol Bay and 0.54 groups/100 km2, or 136 harbor porpoises (95% C.I. 11-1,645) for Cook Inlet. Efforts off Kodiak Island resulted in densities of 1.85 groups/100 km2, or an abundance estimate of 740 (95% C.I. 259-2,115). Surveys off the south side of the Alaska Peninsula found densities of 2.03 groups/100 km2 and an abundance estimate of 551 (95% C.I. 423-719). Surveys of offshore waters from Prince William Sound to Dixon Entrance yielded densities of 4.02 groups/100 km’ and an abundance estimate of 3,982 (95% C.I. 2,567-6,177). Combining all years and areas yielded an uncorrected density estimate of 3.82 porpoises per 100 km2, resulting in an abundance estimate of 8,940 porpoises (CV = 13.8%) with a 95% confidence interval of 6,746-11,848. Using correction factors from other studies to adjust for animals missed by observers, the total number of Alaska harbor porpoises is probably three times this number.