bluuebunny/crossref_metadata_2025 huggingface dataset:
INVESTIGATING THE BIASES IN THE USE OF HARD PREY REMAINS TO IDENTIFY DIET COMPOSITION USING ANTARCTIC FUR SEALS (ARCTOCEPHALUS GAZELLA) IN CAPTIVE FEEDING TRIALS
Authors: Staniland I. J.
Published: August 2006

Abstract

The analysis of pinniped scats has been used to quantify their diet, using prey remains to identify species and to estimate the numbers and sizes of prey consumed. There are, however, potential biases involved with scat analysis and, for this method to be used successfully, these biases need to be quantified. Thirty‐six Antarctic fur seals (Arctocephalus gazella) were fed meals of exclusively either fish, squid, or krill and their scats were collected and analyzed. The major sources of error in the analysis of prey remains from scats were the differential erosion and passage rate of items in relation to their size. However, using simple correction functions, such as those which model otolith erosion, it is possible to reduce these errors. Using plastic beads as dietary markers showed recovery rates were negatively related to their size. Larger squid beaks had lower recovery rates than smaller beaks, but there was no size‐related bias in the recovery rates of krill carapaces. Only 33% of the squid beaks and 27% of the otoliths originally fed were recovered from the scats. Recovery rates were greater for squid (77%) and fish (50%) eye lenses and these structures gave a better estimate of numbers eaten. Differences found between experimentally derived and published regression equations (used to calculate prey sizes eaten from prey remains) highlights the need for regression equations based on local prey characteristics, if these are to be used with any success to describe the prey eaten.
HAWAIIAN MONK SEALS (MONACHUS SCHAUINSLANDI) FORAGING IN DEEP‐WATER CORAL BEDS
Authors: Parrish Frank A. , Abernathy Kyler , Marshall Gregory J. , Buhleier Birgit M.
Published: August 2006

Abstract

Plans to harvest deep‐water corals in the remote Northwestern Hawaiian Islands, close to populations of endangered Hawaiian monk seals (Monachus schauinslandi), have raised concerns about the seals' use of deep‐water habitats. Movements and diving patterns of seals studied at French Frigate Shoals (FFS) Atoll indicated two areas where five males out of 33 instrumented seals dove deep enough (300–500 m) to encounter commercially sought deep‐water corals. Submarine surveys conducted at each location found beds of gold (Gerurdia sp.) and pink (Corallium sp.) precious coral suggesting an overlap between the foraging habitat of some seals and the target of the coral fishery. Areas adjacent to the coral beds that were visually censused using submersibles showed significantly fewer precious corals. Precious coral beds were not found on previous submarine surveys at other regions around FFS, supporting the notion that seals were selecting the areas with corals as forage habitat. Five male seals were fitted with back‐mounted video cameras to document feeding among precious corals. None of the five seals dove deep enough to encounter precious corals (>300 m). However, three of the seals visited beds of black coral (Cirrhipdhes sp.) at shallower depths (∼ 80 m). One seal was observed revisiting the black coral beds on three successive nights to feed on fish hiding among the coral stems.
TRENDS IN MANATEE (TRICHECHUS MANATUS LATIROSTRIS) COUNTS AND HABITAT USE IN TAMPA BAY, 1987–1994: IMPLICATIONS FOR CONSERVATION
Authors: Wright Irene E. , Reynolds John E. , Ackerman Bruce B. , Ward Leslie I. , Weigle Bradley L. , Szelistowski William A.
Published: August 2006

Abstract

Aerial surveys (n= 88) were used to document locations and count sightings of manatees (Trichechus manatus latirostris) in the inshore waters of Tampa Bay, Florida, between November 1987 and May 1994. We made 5,358 sightings of manatees in 1,958 groups. Calves represented 8% of the manatees sighted. Counts were significantly higher in winter (x̄= 79,n= 29 flights) than in non‐winter (x̄= 46,n= 47) months. Counts of manatees in winter increased significantly during the study, but warm‐season counts did not. Regression models demonstrated a relationship between counts and environmental factors. Year‐round counts were related to air temperatures and seasons, with highest counts in winter. However, in the winter season, counts were significantly correlated only with wind speed, not air temperature. Yearround counts were predicted to be curvilinear with highest counts at 15°C average air temperature. Areas used differed with season: in cold weather, 76% of all sightings occurred in zones with warm‐water sources. High‐use areas were identified for summer months. Spatial filter analysis was used to compare manatee density in high‐use areas between two two‐year time periods. The data indicate that (1) manatee use of Tampa Bay was high and increasing in winter, (2) there are particular zones of the bay where conservation of manatees and habitat should be a priority, and (3) sufficient information has been collected for management agencies to develop and implement manatee protection plans.
POPULATION GENETIC STRUCTURE OF FINLESS PORPOISES, NEOPHOCAENA PHOCAENOIDES, IN CHINESE WATERS, INFERRED FROM MITOCHONDRIAL CONTROL REGION SEQUENCES
Authors: Yang Guang , Ren Wenhua , Zhou Kaiya , Liu Shan , Ji Guoqing , Yan Jib , Wang Limin
Published: August 2006

Abstract

Seven hundred and twenty base pairs (bp) of the mitochondrial control region from 73 finless porpoises, Neophocaena phocaenoides, in Chinese waters were sequenced. Thirteen variable sites were determined and 17 haplotypes were defined. Of these, 5 and 7 were found only in the Yellow Sea population and the South China Sea population, respectively, whereas no specific haplo‐type was found in the Yangtze River population. Phylogenetic analyses using NJ and ML algorithm did not divide the haplotypes into monophyletic clades representing recognized geographic populations of finless porpoises in Chinese waters, suggesting the existence of migration and gene flow among populations. Analysis of molecular variance showed the obvious population genetic structure (φst= 0.41, P < 0.05); however, the structure was mainly between either the Yangtze River population or the Yellow Sea population and the South China Sea population. The genetic diversity (nucleotide diversity and haplotypic diversity) of the Yellow Sea population was significantly higher than those of the Yangtze River population and the South China Sea population, suggesting the relatively later divergence of the latter two populations and supporting the Yellow Sea population as the original center of Neophocaena.
DIET OF GRAY WHALES (ESCHRICHTIUS ROBUSTUS) IN CLAYOQUOT SOUND, BRITISH COLUMBIA, CANADA
Authors: Dunham Jason S. , Duffus David A.
Published: August 2006

Abstract

In Clayoquot Sound, British Columbia, gray whales (Eschrichtius robustus) forage for pelagic, hyperbenthic, and benthic invertebrates. Prey types were collected near feeding whales and at sites where no whales were observed to ascertain whales' diets and to describe prey populations and distributions. Characteristics of prey that are examined include species composition, density, biomass, and size. Whales foraged for mysids, Holmesimysis sculpta being the most abundant species collected. Whales foraged near concentrated patches of porcelain crab zoeal larvae, composed primarily of Pachycheles rudis, 21 –294 times the average density and biomass normally collected. Amphipod biomass, composed primarily of Ampelisca agassizi and A. careyi, was 160 ± 150 g/m2 where whales foraged. Larger amphipods, rather than higher density, resulted in higher amphipod biomass between years. Whales foraged where there was a high proportion (61%) of amphipods > 6 mm in length. Whales initially foraged for amphipods along the 20‐m depth contour line; amphipod biomass was best developed and least variable at depths between 16 and 20 m.
GROWTH RATES OF ANTARCTIC FUR SEALS AS INDICES OF ENVIRONMENTAL CONDITIONS
Authors: Reid Keith
Published: August 2006

Abstract

The growth rates of Antarctic fur seal (Arctocephalus gazella) pups estimated from weighing cross‐sections of the population were compared with measured/ inferred changes in the availability of their main prey species, Antarctic krill (Euphausia superba) from 1989 to 2000. There was no relationship between growth rate and mass at weaning and there were counter‐intuitive indications of higher growth rates in years of low krill availability. Biases reflecting changes in the component of the population available for sampling appear to invalidate the widely held assumption that interannual differences in growth rate can reliably be derived from differences in the slope of a linear relationship based on cross‐sectional population samples. A new index was developed, based on the deviation of pup mass at age in each year compared to the multiyear mean, that was not dependent on assumptions of linearity. The indices of growth deviates produced a more logical relationship with other indices of pup development and related more appropriately to variations in prey availability. The potential impact of methodological biases on the interpretation of growth rate suggests that comparisons of growth rates should not rely on assumptions regarding the underlying growth pattern.
GROWTH AND DEVELOPMENT IN FREE‐RANGING HARBOR SEAL (PHOCA VITULINA) PUPS FROM SOUTHERN BRITISH COLUMBIA, CANADA
Authors: Cottrell Paul E. , Jeffries Steven , Beck Brian , Ross Peter S.
Published: August 2006

Abstract

Harbor seals (Phoca vitulina) are small pinnipeds that are widely distributed throughout the temperate coastal regions of the Atlantic and Pacific oceans. We determined birth mass, neonatal growth rates, weaning age, and weaning mass of NE Pacific harbor seals (P. v. richardsi) during a capture‐recapture study that spanned the nursing period (Sidney Island, British Columbia, Canada). Of 46 harbor seal pups initially captured, 28 were classified as newborns (i. e., < 24 h old). Mean body mass of newborns was 11.2 ± SE 0.31 kg. Pups were individually tagged and recaptured throughout the nursing period. Average daily mass gain during the nursing period was 394 ± 26 g. Mean birth mass of males did not differ significantly from females, although pups found with fetal pelage (lanugo) (21.4% of all newborns) were smaller at birth (9.8 ± 0.44 kg) than non‐lanugo pups (11.6 ± 0.33 kg). Mean weaning mass was estimated at 23.6 ± 1.2 kg at a mean weaning age of 32 d ± 1.5 d. While birth and weaning masses differed little from the published data for offshore Sable Island harbor seals (P. v. concolor), British Columbia harbor seals are characterized by half the daily mass gain and a longer nursing period.
AN ALGORITHM TO IMPROVE GEOLOCATION POSITIONS USING SEA SURFACE TEMPERATURE AND DIVING DEPTH
Authors: Beck C. A. , McMillan J. I. , Bowen W. D.
Published: August 2006

Abstract

The at‐sea movement of marine mammals is an important component of their foraging ecology, but has been difficult to study. Geolocation timed‐data recorders (GLTDRs) estimate positions using measured light level to calculate day length and local noon. It is well known that these location estimates are imprecise (mean error of > 1°). Satellite telemetry generally provides a more accurate, but also more expensive means of monitoring movement. We evaluated the accuracy and precision of geolocation positions by comparing these locations with satellite data from Service Argos for eight free‐ranging gray seals (Halichoerns grypus) equipped with both a satellite‐linked data recorder (SDR) and a GLTDR. Geolocation positions differed by 1,026.0 ± 292.28 km from the corresponding Argos locations. We developed an algorithm to correct geolocation positions by comparing surface water temperature (ST) and dive depth collected by GLTDRs with existing sea‐surface temperature and bathymetry databases. The corrected positions were significantly closer (P < 0.025) to the Argos locations of these seals (94.2 ± 8.22 km). The original geolocation positions would have led to incorrect conclusions about the use of space by gray seals; however, the corrected positions can be reliably used to study the large‐scale spatial distribution of individuals.
ABUNDANCE OF INDO‐PACIFIC BOTTLENOSE DOLPHINS, TURSIOPS ADUNCUS, OFF POINT LOOKOUT, QUEENSLAND, AUSTRALIA
Authors: Chilvers B. Louise , Corkeron Peter J.
Published: August 2006

Abstract

Managing escalating human impacts on nearshore cetaceans requires information on a species' demography and distribution patterns at appropriate spatial scales. Identification photographs of individuals of a population of inshore Indo‐Pacific bottlenose dolphins, Tursiops aduncus, were obtained in the open coastal waters off North Stradbroke Island, Australia and used to estimate population density and residency. Five hundred and eighty‐one individuals were identified from 342 school sightings during 1998 and 1999. Mark‐recapture analysis using closed population models estimated a population size of between 700 and 1,000 individuals within the study area during winter, with evidence that the population contained resident individuals. This represents an extremely high number of dolphins within a small area, which requires a pre‐emptive management strategy to ensure their continued occupancy.
MOLTING PHENOLOGY OF HARBOR SEALS ON TUGIDAK ISLAND, ALASKA
Authors: Daniel Raychelle G. , Jemison Lauri A. , Pendleton Grey W. , Crowley Shannon M.
Published: August 2006

Abstract

We documented the progression and timing of the annual molt of harbor seals on Tugidak Island, Alaska, from 1997 to 1999. In all years the timing of molting differed among age‐sex classes. Yearlings molted first, subadults second, adult females third, and lastly adult males. Timing of molting was nearly identical in 1997–1998, whereas in 1999 molting occurred three to six days later for all age‐sex classes except yearlings. Estimated dates when peak proportions of each age‐sex class were molting ranged from 2 August (yearlings) to 2 September (adult males). The number of seals hauled out was positively related to the proportion of seals in the molt and negatively related to the proportion of seals in the postmolt. Population trend estimates, based on aerial counts conducted during a narrow window within the molting period, are likely biased toward certain age‐sex classes. Statistical models used to estimate trend include covariates to help account for within‐year variation in seal numbers, but do not account for compositional changes that occur during molting. Population modeling may elucidate the effects of within‐year population structure on trend estimates. Monitoring molting phenology at additional sites is necessary to determine the extent of geographic variation in molting.
ESTIMATING PUP PRODUCTION OF HARP SEALS, PAGOPHILUS GROENLANDICUS, IN THE NORTHWEST ATLANTIC
Authors: Stenson G. B. , Rivest L.‐P. , Hammill M. O. , Gosselin J. F.
Published: August 2006

Abstract

Photographic and visual aerial surveys to determine current pup production of Northwest Atlantic harp seals were conducted off Newfoundland and in the Gulf of St. Lawrence during March 1999‐Photographic surveys were conducted on all whelping concentrations between 14 and 24 March, whereas a visual survey was made of the southern Gulf concentrations on 14 March. Pup production was estimated to be 739,100 (SE = 96,300, CV = 13.0%) at the Front, 82,600 (SE = 22,500, CV = 27.2%) in the northern Gulf, and 176,200 (SE = 25,400, CV = 14.4%) in the southern Gulf (Magdalen Island) for a total of 997,900 (SE = 102,100, 10.2%). Changes in aerial survey estimates indicate that pup production has increased since 1994. A new method to correct for the temporal change in the proportion of pups present on the ice was examined by fitting the percentage of pups observed in three age‐dependent stages to a Normal distribution. The results were compared to those obtained from a more complex model used previously. The Simple model produced slightly higher, and hence more conservative, estimates of the proportion of births that had occurred before the time of the survey than the Complex model. When using the Simple model fewer assumptions regarding the start date of pupping and the proportion of older pups remaining on the ice were required, the herd had to be followed for a shorter period, and a more convenient means of calculating confidence limits was available.
ENTRANCE INTO STAGE III FASTING BY STARVELING NORTHERN ELEPHANT SEAL PUPS
Authors: Houser Dorian S. , Costa Daniel P.
Published: August 2006

Abstract

Blood metabolites and urea kinetics were determined in starveling elephant seal pups to assess the transition to stage III fasting in this fasting‐adapted species. Five postmolt and two premolt starvelings, denned as having a mass <50 kg, were studied until death or departure to sea. Premolt starvelings died on the rookery while postmolt starvelings departed to sea. Increased mass loss and a significant inverse relationship between mass and the ratio of blood urea nitrogen to creatinine suggested that premolt starvelings had enrered stage III starvation prior to death while urea kinetics suggested that postmolt pups engaged stage III starvation prior to departure. The mean rate of protein catabolism was estimated at 19.4 g/d for departing starvelings, twice the absolute rate and about four times the mass‐specific rate estimated in healthy weanlings after eight weeks of fasting. Three starvelings stranded after departure, possibly as a result of thermoregulatory challenges and inefficient dive behavior. Entrance into stage III fasting interrupts the development of diving in emaciated pups (<50 kg) suggesting that an increased rate of protein catabolism might be linked to the cue to forage. This biochemical trigger is possibly different than the cue to feed in healthy weanlings, which depart the rookery with substantial fat stores.
TRENDS IN ABUNDANCE OF ALASKA HARBOR SEALS, 1983–2001
Authors: Small Robert J. , Pendleton Grey W. , Pitcher Kenneth W.
Published: August 2006

Abstract

We estimated trends in abundance of harbor seals (Phoca vitulina richardsii) using over dispersed, multinomial models and counts obtained during aerial surveys conducted during 1983–2001 in the Ketchikan, Sitka, Kodiak, and Bristol Bay areas of Alaska. Harbor seal numbers increased significantly at 7.4%/yr during 1983–1998 and 5.6%/yr during 1994–1998 in the Ketchikan area, and 6.6%/yr during 1993–2001 in the Kodiak area. Counts were stable (trends not significant) during 1984–2001 (0.7%/yr) and 1995–2001 (‐0.4%/yr) in Sitka, and during 1998–2001 (‐1.3%/yr) in Bristol Bay. The influence of covariates (e.g., survey date, tide height) on trend estimates was significant and varied among areas and across years, demonstrating the need to include covariates in statistical analyses to accurately estimate trend. Our increasing trend estimate for Kodiak represents the first documented increase in harbor seal numbers over a relatively expansive area in the Gulf of Alaska. However, the trend for the Gulf of Alaska stock is equivocal due to the continued decline in Prince William Sound. Similarly, the trend for the Southeast Alaska stock is equivocal based on our increasing (Ketchikan) and stable (Sitka) trend estimates, and a recent decline reported for Glacier Bay. The Bering Sea stock appears stable after a period of possible decline.
AN ENEMA METHOD FOR OBTAINING FECAL MATERIAL FROM KNOWN INDIVIDUAL SEALS ON LAND
Authors: Staniland I. J. , Taylor R. I. , Boyd I. L.
Published: August 2006

Abstract

Female Antarctic fur seals returning ashore after foraging trips were restrained, and fecal material was obtained by introducing approximately one litre of warm water into the animal's colon via the anus. The material then naturally expelled by the animal was collected and analyzed. Of 159 enemas attempted, 148 (93%) produced enough fecal material for subsequent analysis, i.e., where ten or more carapaces or one or more otoliths were recovered. The method produced no obvious external signs of damage to any of the animals, and all were observed suckling their pups within the same season. There was no significant difference in the mean krill sizes collected by enema compared to scat sampling. Also, using their incidence, there was no significant difference in the two sampling methods for any of the fish species considered, though using the proportion of otoliths of a given species of the total otoliths found, there was a difference with one species, Gymnoscopelus nicbolsi. With this technique, it is possible to target individual seals or specific demographic categories for diet analysis. This means that, by using feces collected from enemas, a wider range of questions can be addressed than are currently possible using scat collection alone.
A MODEL LIFE TABLE FOR BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS) FROM THE INDIAN RIVER LAGOON SYSTEM, FLORIDA, U.S.A.
Authors: Stolen Megan K. , Barlow Jay
Published: August 2006

Abstract

Data gathered from 220 stranded bottlenose dolphins (Tursiops truncatus) in the Indian River Lagoon system, Florida, were used to derive a life table. Survivorship curves were fit to the data using Siler's competing‐risk model and a maximum likelihood approach. Population growth was estimated to be between r= 0.0 and 0.046 based on the observed numbers of stranded dolphins. Variance in survival rates was estimated using an individual‐based, age‐structured population projection model. We estimate that the overall annual mortality rate for this population was 9.8% per year. Sex‐specific differences in survivorship were apparent with females outliving males. The overall mortality curve resembles that of other large mammals, with high calf mortality and an exponentially increasing risk of senescent mortality. The inclusion of live‐capture removals of individuals from this population did not significantly affect the estimation of survival parameters for most age classes.
WALRUS LIFE‐HISTORY MOVEMENTS RECONSTRUCTED FROM LEAD ISOTOPES IN ANNUAL LAYERS OF TEETH
Authors: Stewart Robert E. A. , Outridge P. M. , Stern Richard A.
Published: August 2006

Abstract

Putative life history movements of male Atlantic walrus (Odobenus rosmarus nsmarus) harvested at Sanirajak in northern Foxe Basin, Canada, were reconstructed by comparing Pb isotopes in tooth cementum growth layer groups (GLGs) to those in whole‐cementum samples from other walrus of Foxe Basin and nearby areas. The analyses yielded three life history patterns including one, “prodigal sons,” not previously recognized in large mammals. Isotope ratios in GLGs of “local” Sanirajak walrus were relatively constant over time and similar to the whole‐cementum data for most walrus caught in northern Foxe Basin. An “immigrant” walrus acquired the local signal only in young adulthood. In two “prodigal sons,” GLG Pb isotope ratios changed significantly from the local signature after weaning but returned to it in late maturity, shortly before being harvested. Possible recruitment and dispersal areas for the two types of outliers included regions in northern and eastern Hudson Bay, some 300–600 km distant. The return of mature males to their natal group after associating with other groups for several years, as seen in some of the walrus, may be more common among mammals than previously thought. However, without a reconsttuctive technique such as employed here, it could only be detected through long‐term studies of known individuals and all the relevant social groups.
VARIABILITY IN THE DIET OF HARBOR PORPOISES (PHOCOENA PHOCOENA) IN SCOTTISH WATERS 1992–2003
Authors: Santos M. B. , Pierce G. J. , Learmonth J. A. , Reid R. J. , Ross H. M. , Patterson I. A. P. , Reid D. G. , Beare D.
Published: August 2006

Abstract

Interannual, seasonal, and regional variation in the diet of porpoises, Phocoena phocoena, in Scottish (UK) waters was studied using stomach contents of animals stranded between 1992 and 2003. Most samples came from the east coast (including many porpoises killed by bottlenose dolphins), with smaller numbers from the west coast and from Shetland. The most important prey types, in terms of contribution by number and mass, were whiting (Merlangius merlangus) and sand eels (Ammodytidae). Multivariate analysis confirmed the existence of regional, seasonal, and interannual variation in diet, as well as differences (i. e., biases) related to cause of death. These differences were further explored using univariate analyses. Sand eels were more important in the summer months (quarters 2 and 3) and on the east coast, whereas gadids were more important in winter and in the Shetland area. Some, but not all, observed trends in the numerical importance and size of prey taken were consistent with trends in abundance and size of fish taken during research trawl surveys. There was some evidence that porpoises <1 yr old took more gobies (Gobiidae) and shrimps than did older porpoises. Clupeids (herring Clupea harengus and sprat Sprattus sprattus) formed a relatively small proportion of the diet, but their importance varied from year to year. Although possible methodological biases prevent firm conclusions, it appears that the importance of clupeids in porpoise diet may have decreased since the 1960s, mirroring the decline in North Sea herring abundance. The recovery of the North Sea herring stock in recent years is not as yet reflected in porpoise diet.
AERIAL DIGITAL PHOTOGRAPHIC SURVEYS OF NARWHALS,MONODON MONOCEROS, IN NORTHWEST GREENLAND
Authors: Heide‐Jørgensen Mads Peter
Published: August 2006

Abstract

Narwhal (Monodon monoceros) abundance in Inglefield Bredning and adjacent fjords in Northwest Greenland was estimated using aerial digital photographic techniques in August 2001 and 2002. Two digital, large‐format cameras continuously downloaded images to two laptop computers together with information on position, altitude, pitch, and roll of the aircraft. In 2001 a total of 11,628 images were obtained corresponding to a swept area of 840 km2. The survey of the entire area was repeated four times and produced a count of 360 narwhals on the images or an average abundance in the surveyed area of 873 narwhals (CV = 0.35) at the surface. In 2002 the area was surveyed seven times and approximately 11,402 images were obtained. This corresponded to a swept area of 2,208 km2with 566 narwhals counted on the images, and an average estimated abundance of 562 narwhals (CV = 0.24) at the surface. Correcting these figures for availability bias (assuming narwhals are submerged deeper than 2 m for 62% of the time) results in abundance estimates of 2,297 (95% CI: 1,472–3,122) in August 2001 and 1,478 (95% CI 1,164–1,793) in August 2002. The uncorrected estimates, when compared to the results of visual line‐transect surveys conducted in 1985 and 1986 (Born et al. 1994), show a 10% decline in recent years in the abundance of whales visible at the surface.
DETERMINATION OF MANATEE POPULATION TRENDS ALONG THE ATLANTIC COAST OF FLORIDA USING A BAYESIAN APPROACH WITH TEMPERATURE‐ADJUSTED AERIAL SURVEY DATA
Authors: Craig Bruce A. , Reynolds JOHN E.
Published: August 2006

Abstract

In many animal population survey studies, the construction of a stochastic model provides an effective way to capture underlying biological characteristics that contribute to the overall variation in the data. In this paper we develop a stochastic model to assess the population trend and abundance of the Florida manatee,Trichechus manatus latirostris, along the Atlantic coast of the state, using aerial survey data collected at winter aggregation sites between 1982 and 2001. This model accounts for the method by which the manatees were counted, their movements between surveys, and the behavior of the total population over time. The data suggest an overall increase in the population from 1982 to 1989 of around 5%–7%, a reduction in growth or a leveling off (0%–4% annual growth) from 1990 to 1993, and then an increase again of around 3%–6% since 1994. In winter 2001–2002 (the most recent survey season for which analyses were done), we estimated the adult manatee population along the east coast of Florida to be 1,607 individuals (range = 1,353–1,972; 95% credible interval). Our estimate of manatee abundance corresponds well with maximum counts (approximately 1,600 manatees) produced during synoptic aerial surveys under optimal conditions. Our calculations of trends correspond well with mark and recapture analyses of trends in survival of adult manatees along the east coast through the early 1990s. Our population trend estimates since that time are more optimistic than those generated by mark‐recapture models.
LATERAL MANDIBULAR WALL THICKNESS IN TURSIOPS TRUNCATUS: VARIATION DUE TO SEX AND AGE
Authors: Nummela Sirpa , Kosove Jason E. , Lancaster Terry E. , Thewissen J. G. M.
Published: August 2006

Abstract

In odontocetes the mandibular bone serves two functions: to capture prey, and as a means of the reception and transmission of sound waves through a fat body in the mandibular canal, which opens posteriorly as the mandibular foramen. The posterior part of the lateral wall of the odontocete mandible is thin, and appears to represent a compromise between a strong mandible for prey capture and a thin vibrating plate for hearing. We studied the intraspecific variation of minimum thickness of the lateral mandibular wall along four transects (T1‐T4) at the area of the mandibular foramen, in relation to the skull size and the mandibular size in different‐aged bottlenose dolphins, Tursiops truncatus (18 females between 1 and 42 yr, 17 males between 1 and 32 yr). The minimum thickness was absolutely at its lowest at the most posterior transect T1, but did not vary significantly between the sexes or between the ages. The minimum thickness varied significantly at the two most anterior transects, T3 and T4, both between the sexes and among the ages. The thickness increased throughout life among males, whereas in females it first increased and then starts to decrease around the age of 20.
DEMOGRAPHIC PARAMETERS OF INDO‐PACIFIC BOTTLENOSE DOLPHINS (TURSIOPS ADUNCUS) AROUND MIKURA ISLAND, JAPAN
Authors: Kogi Kazunobu , Hishii Toru , Imamura Ayami , Iwatani Takako , Dudzinski Kathleen M.
Published: August 2006

Abstract

Long‐term identification surveys were conducted using video records on Indo‐Pacific bottlenose dolphin (Tursiops aduncus) around Mikura Island, Tokyo, Japan. On 246 surveys, 3,996 min of video were recorded during each summer season from 1994 to 2001. Two hundred and twenty individuals were observed, including juveniles and neonates, that were not cataloged, but could be identified by association with their mothers. Over the eight‐year study period, the total number of identified and cataloged individuals was 169. The annual number of newly identified dolphins stabilized at ∼ 10 after 1995. In the middle of each research season, a plateau in the number of reidentified individuals was reached. Most of the dolphins were observed frequently–percentages of reidentified dolphins in adjoining years were greater than 86% and 62 individuals were seen consecutively during the eight years. There were no significant differences in the sex ratio between years. The sex ratio was skewed significantly towards male for subadults and towards female for adults. The survival rate of one‐year‐old calves was 86.7%, and the mean age at weaning was 3.5 yr. The calving interval averaged 3.4 yr among adult females. The mean annual birth, fecundity, and recruitment rates were 0.071, 0.239, and 0.068, respectively. Mikura Island is located in the pelagic ocean with no protected bay area existing around the island. Dolphins do not regularly inhabit any other locations besides Mikura within the Izu island chain. Thus, this island may be important core habitat of these dolphins.
VASOMOTOR RESPONSES OF ISOLATED PERIPHERAL BLOOD VESSELS FROM BOWHEAD WHALES: THERMOREGULATORY IMPLICATIONS
Authors: Elsner Robert , George J. Craig , O'hara Todd
Published: August 2006

Abstract

Temperature regulation in bowhead whales, Balaena mysticetus, is supported by the characteristic cetacean peripheral circulation, especially notable in the tail flukes. Blood vessels serving this function consist of countercurrent heat exchangers (network of veins surrounding a central artery) favoring heat conservation and an alternate routing via arteriovenous anastomoses (AVAs) providing for heat dissipation. We tested the vasomotor responses of isolated segments of countercurrent arteries and AVAs from the bowhead tail flukes to norepinephrine (NOR), the sympathetic adrenergic neurotransmitter. Isometric tension developed during exposure to a micromolar concentration of NOR was consistently higher in AVAs than in arteries. Accordingly, the AVAs are subject to sympathetic vasoconstriction, and this activation directs blood flow to countercurrent heat exchangers and results in heat conservation. In contrast, AVA relaxation by reduced sympathetic activation favors increased blood flow through AVAs and consequent peripheral heat loss.
CYTOCHROME P450 1A1 EXPRESSION IN CETACEAN INTEGUMENT: IMPLICATIONS FOR DETECTING CONTAMINANT EXPOSURE AND EFFECTS
Authors: Angell Carolyn Miller , Wilson Joanna Y. , Moore Michael J. , Stegeman John J.
Published: August 2006

Abstract

Contaminant related health risks to marine mammals are typically inferred from the levels of contaminants measured in blubber. Such measurements alone are insufficient to indicate the likelihood of biological effects from contaminant exposure, especially for contaminants that do not bioaccumulate. Cytochrome P450 1A1 (CYP1A1) in mammals is induced by, and involved in, the metabolism of planar halogenated aromatic hydrocarbons and polycyclic aromatic hydrocarbons, chemicals of concern in aquatic systems. CYP1A induction is a molecular response to exposure to these inducers in many vertebrates. Using immunohistochemistry, we semiquantitatively measured CYP1A1 expression in integument (epidermis and blubber) collected by biopsy or at necropsy from 17 species of cetaceans. CYP1A1 expression was detected in all species and, in some cases, varied both within and between species. CYP1A1 expression in mysticetes was comparable to that in odontocetes. Assessing how the differences in contaminant burdens, life history parameters, and physiological condition between individuals, populations, or species affect CYP1A1 expression in cetacean integument is essential to the interpretation of this induction as a biomarker of exposure to and effects of contaminants. Detection of CYP1A1 expression in integument samples offers a relatively simple, non‐lethal technique to study biological changes associated with contaminant exposure in cetaceans.
ENVIRONMENTAL FACTORS INFLUENCING THE DISTRIBUTION OF SOUTHERN RIGHT WHALES (EUBALAENA AUSTRALIS) ON THE SOUTH COAST OF SOUTH AFRICA I: BROAD SCALE PATTERNS
Authors: Elwen Simon H. , Best Peter B.
Published: August 2006

Abstract

Aerial surveys over the last 32 yr have shown that the distribution of southern right whales Eubalaena australis along the south coast of South Africa is markedly discontinuous, but highly predictable. A GIS was used at a variety of scales to investigate whether this pattern was related to environmental characteristics. Whale distribution was analyzed as density per 20‐min bin of longitude over two temporal and spatial scales, namely 15 bins for 32 yr, and a wider scale but shorter time period, 23 bins for 19 yr, as well as using three years of GPS accuracy data (15 bins) for finer scale analysis. Environmental factors tested were depth, distance from shore, sea floor slope, protection from swell, protection from wind, and shore type. The majority of whales were concentrated in areas that provided reasonable protection from open ocean swell and seasonal winds, and had sedimentary floors with gentle slopes. They generally avoided exposed rocky shorelines. Cow‐calf pairs were found significantly closer to shore and in shallower water than unaccompanied whales, particularly off sandy beaches. Habitat choice at this time of year may be related both to energy conservation for calves and lactating females (calm sea conditions) and to protection of the new‐born.
SHIPBOARD LINE TRANSECT SURVEYS OF CRABEATER SEAL ABUNDANCE IN THE PACK‐ICE OFF EAST ANTARCTICA: EVALUATION OF ASSUMPTIONS
Authors: Southwell Colin , Mare Bill De La , Borchers David , Burt Louise
Published: August 2006

Abstract

We examine the extent to which the assumptions underlying line transect sampling are satisfied in shipboard surveys of crabeater seals (Lobodon carcinophaga) hauled out on the Antarctic pack‐ice. Measurement of the perpendicular distance of seal groups from the ship with an electronic inclinometer fitted to a rifle stock was unbiased. Crabeater seals showed little movement in response to the approaching ship. Movement away from the ship by seals close to the ship's track was partially responsible for a relative lack of sightings close to the transect‐line, but otherwise had little effect on the sighting histogram. Minor deviations from the transect direction to avoid running over seals violated the assumption of uniform distribution of groups, and contributed to a relative lack in sightings close to (<40 m) the transect‐line. We estimate that 5%‐10% of seal groups close to the transect‐line were not sighted by bridge observers prior to passing abeam of the ship, but most of these missed groups were likely to have been sighted some distance behind‐abeam. Shipboard transects provided a biased sample of four environmental features known to be related to crabeater seal abundance because of logistical difficulties in the ship traversing along straight transects through thick ice. Calculation of transect length L from successive GPS locations was mildly sensitive to the frequency of locations. We provide analytical recommendations to reduce or eliminate the effect of assumption violation when present and hence minimize bias in abundance estimation.
THE SOCIAL STRUCTURE OF BOTTLENOSE DOLPHINS, TURSIOPS TRUNCATUS, IN THE BAHAMAS
Authors: Rogers Cindy A. , Brunnick Barbara J. , Herzing Denise L. , Baldwin John D.
Published: August 2006

Abstract

The social structure of coastal ecotype bottlenose dolphins, Tursiops truncatus, is largely unknown as they inhabit regions far from shore. This study reports on a community of bottlenose dolphins ≥ 27 km from Grand Bahama Island (May‐September, 1993–2002). Resident and non‐resident dolphins occurred in the area. Some dolphins traveled over 320 km between communities; others showed long‐ term site fidelity up to 17 yr. Average group size was 3–5, and was significantly larger with calves present and significantly smaller when traveling. The half‐weight index was used to determine coefficients of association (COA) for individuals of known sex annually and for pooled years. Permutation tests revealed non‐random associations and presence of preferred/avoided companions in all data sets. Annual COAs were low: female‐female χ= 0.31, male‐male χ= 0.30, and mixed‐sex χ= 0.26. Mother‐calf associations showed the highest values. Some males formed strong, long‐term bonds. Female COAs fluctuated with reproductive status. Using pooled data, COAs were lower and the same basic trends were evident. However, strong associations seen in the annual data were not evident in pooled data. Bottlenose dolphins that inhabit offshore, shallow water show many of the same social structure characteristics as in well‐studied coastal populations.
Definitions and aetiology of myalgic encephalomyelitis: how the Canadian consensus clinical definition of myalgic encephalomyelitis works
Authors: Carruthers B M
Published: August 2006

A perspective on the various definitions of myalgic encephalomyelitis and the process of discovering its aetiology is presented. The importance of clinical guidelines is emphasised to encourage clinicians to provide clear descriptions of their individual patients required for proper clinical activity; diagnosis, estimation of severity of effect, prognosis, treatment and rehabilitation. This individual knowledge is informed by general and (hopefully) publicly confirmed knowledge resulting from scientific research during the second-person interaction which lies at the core of the clinical encounter. Both types of knowledge are essential.
Is histone loss a common feature of DNA metabolism regulation?This paper is one of a selection of papers published in this Special Issue, entitled 27th International West Coast Chromatin and Chromosome Conference, and has undergone the Journal's usual peer review process.
Authors: Morillon Antonin
Published: August 2006

Chromatin modifications play a crucial role in regulating DNA metabolism. Chromatin structures can be remodeled by covalently modifying histones, by shifting nucleosomes along the DNA, and by changing the histone composition of nucleosomes. Lately, nucleosome displacement has been extensively described within transcribed genes and DNA breaks. This review focuses on recently published work that describes the relationships between histone modification/exchange and nucleosome displacement.
Analyses of linker histone – chromatin interactions in situThis paper is one of a selection of papers published in this Special Issue, entitled 27th International West Coast Chromatin and Chromosome Conference, and has undergone the Journal's usual peer review process.
Authors: Rundquist Ingemar , Lindner Herbert H.
Published: August 2006

Recent studies, using cytometric techniques based on fluorescence microscopy, have provided new information on how linker histones interact with chromatin in vivo or in situ. In particular, the use of green fluorescent proteins (GFPs) has enabled detailed studies of how individual H1 subtypes, and specific motifs in them, interact with chromatin in vivo. Furthermore, the development of cytochemical methods to study the interaction between linker histones and chromatin using DNA-binding fluorochromes as indirect probes for linker histone affinity in situ, in combination with highly sensitive and specific analytical methods, has provided additional information on the interactions between linker histones and chromatin in several cell systems. Such results verified that linker histones have a substantially higher affinity for chromatin in mature chicken erythrocytes than in frog erythrocytes, and they also indicated that the affinity decreased during differentiation of the frog erythrocytes. Furthermore, in cultured human fibroblasts, the linker histones showed a relatively high affinity for chromatin in interphase, whereas it showed a significantly lower affinity in highly condensed metaphase chromosomes. This method also enables the analysis of linker histone affinity for chromatin in H1-depleted fibroblasts reconstituted with purified linker histones. No consistent correlation between linker histone affinity and chromatin condensation has so far been detected.
γH2AX and its role in DNA double-strand break repairThis paper is one of a selection of papers published in this Special Issue, entitled 27th International West Coast Chromatin and Chromosome Conference, and has undergone the Journal's usual peer review process.
Authors: Fillingham Jeffrey , Keogh Michael-Christopher , Krogan Nevan J.
Published: August 2006

One of the earliest responses to a DNA double-strand break (DSB) is the carboxy-terminal phosphorylation of budding yeast H2A (metazoan histone H2AX) to create γH2A (or γΗ2ΑX). This chromatin modification stretches more than tens of kilobases around the DSB and has been proposed to play numerous roles in break recognition and repair, although it may not be the primary signal for many of these events. Studies suggest that γH2A(X) has 2 more direct roles: (i) to recruit cohesin around the DSB, and (ii) to maintain a checkpoint arrest. Recent work has identified other factors, including chromatin remodelers and protein phosphatases, which target γH2A(X) and regulate DSB repair/recovery.
Five repair pathways in one context: chromatin modification during DNA repairThis paper is one of a selection of papers published in this Special Issue, entitled 27th International West Coast Chromatin and Chromosome Conference, and has undergone the Journal's usual peer review process.
Authors: Ataian Yeganeh , Krebs Jocelyn E.
Published: August 2006

The eukaryotic cell is faced with more than 10 000 various kinds of DNA lesions per day. Failure to repair such lesions can lead to mutations, genomic instability, or cell death. Therefore, cells have developed 5 major repair pathways in which different kinds of DNA damage can be detected and repaired: homologous recombination, nonhomologous end joining, nucleotide excision repair, base excision repair, and mismatch repair. However, the efficient repair of DNA damage is complicated by the fact that the genomic DNA is packaged through histone and nonhistone proteins into chromatin, a highly condensed structure that hinders DNA accessibility and its subsequent repair. Therefore, the cellular repair machinery has to circumvent this natural barrier to gain access to the damaged site in a timely manner. Repair of DNA lesions in the context of chromatin occurs with the assistance of ATP-dependent chromatin-remodeling enzymes and histone-modifying enzymes, which allow access of the necessary repair factors to the lesion. Here we review recent studies that elucidate the interplay between chromatin modifiers / remodelers and the major DNA repair pathways.
Beyond the walls of the nucleus: the role of histones in cellular signaling and innate immunityThis paper is one of a selection of papers published in this Special Issue, entitled 27th International West Coast Chromatin and Chromosome Conference, and has undergone the Journal's usual peer review process.
Authors: Parseghian Missag H. , Luhrs Keith A.
Published: August 2006

Although they are one of the oldest family of proteins known (first described in 1884 by Kossel), histones continue to surprise researchers with their ever expanding roles in biology. In the past 25 years, the view of core histone octamers as a simple spool around which DNA in the nucleus is wound and linker histones as mere fasteners clipping it all together has transformed into the realization that histones play a vital role in transcriptional regulation. Through post-translational modifications, histones control the accessibility of transcription factors and a host of other proteins to multiple, conceivably thousands of, genes at once. While researchers have spent decades deciphering the role of histones in the overall structure of chromatin, it might surprise some to find that an entirely separate faction of scientists have focused on the role of histones beyond the confines of the nuclear envelope. In the past decade, there has been an accumulation of observations that suggest that histones can be found at the mitochondrion during the onset of apoptotic signaling and even at the cell surface, acting as a receptor for bacterial and viral proteins. More provocatively, immunologists are becoming convinced that they can also be found in the lumen of several tissues, acting as antimicrobial agents—critical components of an ancient innate immune system. Perhaps nowhere is this observation as dramatic as in the ability of neutrophils to entrap bacterial pathogens by casting out "nets" of DNA and histones that not only act as a physical barrier, but also display bactericidal activity. As our views regarding the role of histones inside and outside the cell evolve, some have begun to develop therapies that either utilize or target histones in the fight against cancer, microbial infection, and autoimmune disease. It is our goal here to begin the process of merging the dichotomous lives of histones both within and without the nuclear membrane.