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1.
Peter F. Olesiuk Linda M. Nichol Margaret J. Sowden John K. B. Ford 《Marine Mammal Science》2002,18(4):843-862
We describe an experiment conducted to assess the impact of the sound generated by an acoustic harassment device (AHD) on the relative abundance and distribution of harbor porpoises ( Phocoena phocoena ) in Retreat Passage, British Columbia. During control periods when the AHD was inactive, the mean number of porpoises observed in the study area was 0.39 for broad area scans conducted with the naked eye and 0.48 for narrow sector scans conducted with binoculars. Abundance declined precipitously when the AHD was activated, to 0.007 porpoises per broad area scan and 0.018 per narrow sector scan. The mean number of porpoise resightings while tracking their movements also declined from 12.2 to 13.6 per sighting during control periods to 1.1–1.9 per sighting when the AHD was activated, which suggested that the few porpoises that ventured into the study area spent less time within it when the AHD was activated. The effect of the AHD diminished with distance. No porpoises were observed within 200 m of the AHD when it was activated. The number of sightings and resightings observed when it was activated was less than 0.2% of the number expected had there been no AHD effect at a range of 200–399 m, 1.4% the number expected at a range of 400–599 m, varied between 2.5% and 3.3% of the number expected at a range of 600–2,499 m, and was 8.1% the number expected at a range of 2,500–3,500 m, which suggested that the impact of the AHD extended beyond our maximum sighting range of 3.5 km. 相似文献
2.
Due to the difficulties and limitations associated with field sampling of marine mammals, quantitative surveys on their parasites are still scarce in Japan. We here report the infection statuses of intestinal parasites in harbor porpoises (n = 34) and Dall's porpoises (n = 10), bycaught between 2014 and 2018 by a bottom set-net fishery in the northern part of the Nemuro Strait, Japan. Necropsies of the harbor porpoises recovered one digenean, Synthesium nipponicum, and two acanthocephalans, Corynosoma sp. and Bolbosoma sp.; no infection was observed in the Dall's porpoises. The dominant parasites were Corynosoma sp. and S. nipponicum, with a prevalence of 73.53 and 64.71% and a mean abundance of 43.88 and 7.38 individuals, respectively. Although the two porpoise-species have a sympatric distribution in this narrow strait, the findings support the existence of trophic-link dependences, which can differentially affect vulnerability to these parasites. 相似文献
3.
Micha?l C. Fontaine Krystal A. Tolley Johan R. Michaux Alexei Birkun Jr Marisa Ferreira Thierry Jauniaux ángela Llavona Bayram ?ztürk Ayaka A ?ztürk Vincent Ridoux Emer Rogan Marina Sequeira Jean-Marie Bouquegneau Stuart J. E. Baird 《Proceedings. Biological sciences / The Royal Society》2010,277(1695):2829-2837
Recent climate change has triggered profound reorganization in northeast Atlantic ecosystems, with substantial impact on the distribution of marine assemblages from plankton to fishes. However, assessing the repercussions on apex marine predators remains a challenging issue, especially for pelagic species. In this study, we use Bayesian coalescent modelling of microsatellite variation to track the population demographic history of one of the smallest temperate cetaceans, the harbour porpoise (Phocoena phocoena) in European waters. Combining genetic inferences with palaeo-oceanographic and historical records provides strong evidence that populations of harbour porpoises have responded markedly to the recent climate-driven reorganization in the eastern North Atlantic food web. This response includes the isolation of porpoises in Iberian waters from those further north only approximately 300 years ago with a predominant northward migration, contemporaneous with the warming trend underway since the ‘Little Ice Age’ period and with the ongoing retreat of cold-water fishes from the Bay of Biscay. The extinction or exodus of harbour porpoises from the Mediterranean Sea (leaving an isolated relict population in the Black Sea) has lacked a coherent explanation. The present results suggest that the fragmentation of harbour distribution range in the Mediterranean Sea was triggered during the warm ‘Mid-Holocene Optimum’ period (approx. 5000 years ago), by the end of the post-glacial nutrient-rich ‘Sapropel’ conditions that prevailed before that time. 相似文献
4.
Janneke M. Ransijn Philip S. Hammond Mardik F. Leopold Signe Sveegaard Sophie C. Smout 《Ecology and evolution》2021,11(23):17458
- Quantifying consumption and prey choice for marine predator species is key to understanding their interaction with prey species, fisheries, and the ecosystem as a whole. However, parameterizing a functional response for large predators can be challenging because of the difficulty in obtaining the required data on predator diet and on the availability of multiple prey species.
- This study modeled a multi‐species functional response (MSFR) to describe the relationship between consumption by harbour porpoises (Phocoena phocoena) and the availability of multiple prey species in the southern North Sea. Bayesian methodology was employed to estimate MSFR parameters and to incorporate uncertainties in diet and prey availability estimates. Prey consumption was estimated from stomach content data from stranded harbour porpoises. Prey availability to harbour porpoises was estimated based on the spatial overlap between prey distributions, estimated from fish survey data, and porpoise foraging range in the days prior to stranding predicted from telemetry data.
- Results indicated a preference for sandeels in the study area. Prey switching behavior (change in preference dependent on prey abundance) was confirmed by the favored type III functional response model. Variation in the size of the foraging range (estimated area where harbour porpoises could have foraged prior to stranding) did not alter the overall pattern of the results or conclusions.
- Integrating datasets on prey consumption from strandings, predator foraging distribution using telemetry, and prey availability from fish surveys into the modeling approach provides a methodological framework that may be appropriate for fitting MSFRs for other predators.
5.
Peter J. H. Reijnders 《Aquatic Ecology》1992,26(1):75-85
Changes during the last 40 years of abundance and occurrence of harbour porpoises in the North Sea are illustrated as consequences
of changes in environmental factors. The major changes in environmental conditions which influenced the presence of harbour
porpoises in the North Sea, in particular the southern North sea, are postulated to be changes in prey availability and changes
in accidental catches. Limitations of prey made them move out of the coastal areas, but accidental catch has reduced their
overall abundance. Prey availability was affected by limitation of herring and mackerel as the major food source, caused initially
by overfishing, followed by a shift in spawning and feeding areas towards the North. Without ignoring the possible complementary
impact of pollution and disturbance, it is believed that accidental catch is the only other major threat. The present size
of the harbour porpoise population(s) in the northeast Atlantic, including the stock in the Danish inner waters, is estimated
to average 160,000 (range 70,000–225,000) specimens. However, this should not divert the attention from the fact that bycatch
and directed catch have significantly reduced the size of the North Sea harbour porpoise populations (including the Baltic),
by at least between 53,000–89,000 animals, and more likely the higher end of the range. It is emphasized that management measures
should be taken in order to reduce the bycatch of porpoises as was already agreed at the latest Ministerial North Sea Conference.
The only short-term, pragmatic and efficient way to assess whether the population will benefit from increasing prey availability
is to organise international sighting surveys. Then it may be possible to obtain a clear perception of whether the porpoise
has only temporarily moved out of the southern North Sea or whether we are dealing with a decreased population, unable to
recover because it can not sustain the existing accidental catches. 相似文献
6.
Aerial surveys of marine mammals are routinely conducted to assess and monitor species’ habitat use and population status. In Australia, dugongs (Dugong dugon) are regularly surveyed and long-term datasets have formed the basis for defining habitat of high conservation value and risk assessments of human impacts. Unmanned aerial vehicles (UAVs) may facilitate more accurate, human-risk free, and cheaper aerial surveys. We undertook the first Australian UAV survey trial in Shark Bay, western Australia. We conducted seven flights of the ScanEagle UAV, mounted with a digital SLR camera payload. During each flight, ten transects covering a 1.3 km2 area frequently used by dugongs, were flown at 500, 750 and 1000 ft. Image (photograph) capture was controlled via the Ground Control Station and the capture rate was scheduled to achieve a prescribed 10% overlap between images along transect lines. Images were manually reviewed post hoc for animals and scored according to sun glitter, Beaufort Sea state and turbidity. We captured 6243 images, 627 containing dugongs. We also identified whales, dolphins, turtles and a range of other fauna. Of all possible dugong sightings, 95% (CI = 90%, 98%) were subjectively classed as ‘certain’ (unmistakably dugongs). Neither our dugong sighting rate, nor our ability to identify dugongs with certainty, were affected by UAV altitude. Turbidity was the only environmental variable significantly affecting the dugong sighting rate. Our results suggest that UAV systems may not be limited by sea state conditions in the same manner as sightings from manned surveys. The overlap between images proved valuable for detecting animals that were masked by sun glitter in the corners of images, and identifying animals initially captured at awkward body angles. This initial trial of a basic camera system has successfully demonstrated that the ScanEagle UAV has great potential as a tool for marine mammal aerial surveys. 相似文献
7.
Akinori Takahashi Nobuo Kokubun Yoshihisa Mori Hyoung-Chul Shin 《Polar Biology》2008,31(10):1291-1294
Animal-borne camera loggers were used to examine the patterns of prey encounter and feeding behaviour of gentoo penguins at
King George Island, Antarctica. The still images from the camera loggers showed that the penguins encountered the swarms of
krill for 25.5% (range: 8–38%) of their dives (>5 m) on average, during their foraging trips (mean duration of 5.4 h, n = 7 trips). They encountered krill swarms during the dives to 10–70 m depth, in pelagic as well as benthic habitats. In the
benthic habitat, the penguins swam just above the sea floor and headed downward over a krill swarm, probably using the sea
floor to assist them to feed on mobile swarms. The shallow coastal waters would be the important foraging habitat of gentoo
penguins breeding in King George Island. 相似文献
8.
Clara Ortiz-Alvarez Joanna Alfaro-Shigueto Jeffrey C. Mangel 《Marine Mammal Science》2021,37(3):993-1007
The marine otter (Lontra felina) has a patchy distribution associated with rocky coastlines along the Pacific coast of South America. In Peru marine otters are found from La Libertad (8°04′S) to Tacna (18°09′S), however, few studies have assessed its population and conservation status. To assess marine otters' current distribution along the Peru coastline, we conducted visual surveys and collected environmental characteristics such as human presence and habitat type. We surveyed 20 locations from five regions where otter presence was based on signs of detection (spraints, food leftovers, tracks, or direct observations). In addition, data on human presence, habitat type, and geographic location were also collected. Across the 20 locations, 268 sections were scanned, and marine otters were detected in 90% (n = 18) of locations and in 19% (n = 52) of sections. Spraints were the most frequent sign detected while direct observations occurred only in seven locations. Our analysis indicates habitat features play an important role in marine otter presence, with habitats with large rocks providing preferred conditions. Our study provides information on marine otter distribution along the Peru coastline that can assist in the identification of locations for focused conservation initiatives and strategies, which should be coordinated among regions to strengthen their design and implementation. 相似文献
9.
J. M. Blumenthal T. J. Austin J. B. Bothwell A. C. Broderick G. Ebanks-Petrie J. R. Olynik M. F. Orr J. L. Solomon M. J. Witt B. J. Godley 《Coral reefs (Online)》2009,28(1):55-65
As historically abundant spongivores, hawksbill turtles Eretmochelys imbricata likely played a key ecological role on coral reefs. However, coral reefs are now experiencing global declines and many hawksbill
populations are critically reduced. For endangered species, tracking movement has been recognized as fundamental to management.
Since movements in marine vertebrates encompass three dimensions, evaluation of diving behavior and range is required to characterize
marine turtle habitat. In this study, habitat use of hawksbill turtles on a Caribbean coral reef was elucidated by quantifying
diel depth utilization and movements in relation to the boundaries of marine protected areas. Time depth recorders (TDRs)
and ultrasonic tags were deployed on 21 Cayman Islands hawksbills, ranging in size from 26.4 to 58.4 cm straight carapace
length. Study animals displayed pronounced diel patterns of diurnal activity and nocturnal resting, where diurnal dives were
significantly shorter, deeper, and more active. Mean diurnal dive depth (±SD) was 8 ± 5 m, range 2–20 m, mean nocturnal dive
depth was 5 ± 5 m, range 1–14 m, and maximum diurnal dive depth was 43 ± 27 m, range 7–91 m. Larger individuals performed
significantly longer dives. Body mass was significantly correlated with mean dive depth for nocturnal but not diurnal dives.
However, maximum diurnal dive depth was significantly correlated with body mass, suggesting partitioning of vertical habitat
by size. Thus, variable dive capacity may reduce intraspecific competition and provide resistance to degradation in shallow
habitats. Larger hawksbills may also represent important predators on deep reefs, creating a broad ecological footprint over
a range of depths.
Communicated by Biology Editor Dr Mark McCormick 相似文献
10.
The mountain tapir Tapirus pinchaque is one of the largest and most threatened mammals of the northern South American Andes. It is distributed in montane forests and paramos mainly above 2000 m, from Colombia to north Peru. The species is categorised as globally Endangered and is mainly threatened by habitat degradation, habitat loss and fragmentation. Although up-to-date information is lacking in Peru on its distribution, population and conservation status, this population could play an important part in the global persistence of the species. We compiled all known recent occurrence records for the species from Peru, as well as data from camera traps with an effort of over 10,000 camera/days between 2016 and 2018. We modelled the tapir’s distribution using remote-sensed vegetation indices, topographic and bioclimatic variables in MaxEnt, followed by post-processing steps to remove unoccupied areas, to produce a current range map for the species in Peru. We overlaid this with spatial information on threats and protected areas. We estimate a range of almost 183,000 ha in Peru, in two main regions, north and south of the Huancabamba river, of which approximately 60% is within protected areas. However, protection gaps still exist, especially in the south of its range. Mining concessions cover 27% of its current range and we estimate 28,000 ha of forest loss within its extent of occurrence between 2001 and 2020. We provide recommendations for its conservation, including priority areas for increased protection, binational initiatives to ensure connectivity with populations in Ecuador and to use the tapir as a flagship species in efforts to protect montane ecosystems for water conservation. 相似文献
11.
Ann Marie Aglionby Harding Carsten Egevang Wojciech Walkusz Flemming Merkel Stéphane Blanc David Grémillet 《Polar Biology》2009,32(5):785-796
Interpreting the impact of environmental change on food webs requires a clear understanding of predator–prey interactions.
Such knowledge is often lacking in the marine environment where the foraging behaviour and prey requirements of some of the
major top-predators remains mysterious. For example, very little is known about the underwater foraging behaviour of the little
auk, the most numerous seabird in the North Atlantic. In 2004, we used time–depth-recorders at two breeding colonies in East
Greenland to examine the diving behaviour of this small, planktivorous seabird during the chick-rearing period. Due to technical
difficulties data were only collected for four individuals, but recordings showed that birds dive up to 240 times a day to
maximum depths of 27 m (average 10 m), with maximum dive durations of 90 s (average 52 s). In addition, we collected the chick
meals from 35 individuals, which were dominated by Calanus copepods (95%), and also determined the field metabolic rates (FMR) of 14 individuals using the doubly labelled water technique,
which averaged 609.9 kJ day−1. We integrated information on diving duration with chick diet and FMR to estimate the prey requirements and underwater capture
rates of little auks using a Monte Carlo simulation. Chick-rearing little auks needed to catch about 59,800 copepods day−1, which is equivalent to about six copepods caught per second spent underwater. These astonishing results strongly suggest
that little auks are, at least partly, filter-feeding, and underline the importance of highly productive, cool marine areas
that harbour dense patches of large, energy-rich copepods. 相似文献
12.
Floris M. van Beest Rune Dietz Anders Galatius Line Anker Kyhn Signe Sveegaard Jonas Teilmann 《Ecology and evolution》2022,12(7)
Understanding how environmental and climate change can alter habitat overlap of marine predators has great value for the management and conservation of marine ecosystems. Here, we estimated spatiotemporal changes in habitat suitability and inter‐specific overlap among three marine predators: Baltic gray seals (Halichoerus grypus), harbor seals (Phoca vitulina), and harbor porpoises (Phocoena phocoena) under contemporary and future conditions. Location data (>200 tagged individuals) were collected in the southwestern region of the Baltic Sea; one of the fastest‐warming semi‐enclosed seas in the world. We used the maximum entropy (MaxEnt) algorithm to estimate changes in total area size and overlap of species‐specific habitat suitability between 1997–2020 and 2091–2100. Predictor variables included environmental and climate‐sensitive oceanographic conditions in the area. Sea‐level rise, sea surface temperature, and salinity data were taken from representative concentration pathways [RCPs] scenarios 6.0 and 8.5 to forecast potential climate change effects. Model output suggested that habitat suitability of Baltic gray seals will decline over space and time, driven by changes in sea surface salinity and a loss of currently available haulout sites following sea‐level rise in the future. A similar, although weaker, effect was observed for harbor seals, while suitability of habitat for harbor porpoises was predicted to increase slightly over space and time. Inter‐specific overlap in highly suitable habitats was also predicted to increase slightly under RCP scenario 6.0 when compared to contemporary conditions, but to disappear under RCP scenario 8.5. Our study suggests that marine predators in the southwestern Baltic Sea may respond differently to future climatic conditions, leading to divergent shifts in habitat suitability that are likely to decrease inter‐specific overlap over time and space. We conclude that climate change can lead to a marked redistribution of area use by marine predators in the region, which may influence local food‐web dynamics and ecosystem functioning. 相似文献
13.
Prenger-Berninghoff E Siebert U Stede M König A Weiss R Baljer G 《Diseases of aquatic organisms》2008,81(1):65-71
In this study, organ samples from 426 common seals Phoca vitulina, 298 harbour porpoises Phocoena phocoena, 34 grey seals Halichoerus grypus and 10 other marine mammals were assessed for the presence of Brucella species. Forty-seven common seals, 2 harbour porpoises and 1 grey seal were found to be positive for these bacteria. A total of 91 Brucella strains were successfully isolated, due to the fact that Brucella spp. were found in more than one organ sample in 15 animals. The primary organ in which the bacteria were present was the lung. In addition, 2 strains were isolated from lungworms (Parafilaroides spp.). Forty-nine of the isolated strains were selected for further analysis using conventional phenotyping methods. Molecular characterisation was carried out by analysing the IS711 and omp2 loci. With respect to the distribution of the IS711 loci in the genome, the 49 field isolates differed strongly from the terrestrial Brucella species and marginally from the marine Brucella reference strain NCTC12890. Based on the results of the PCR restriction fragment length polymorphism (PCR-RFLP) investigation of the omp2 locus, the majority of the Brucella field isolates were classified as B. pinnipediae, recently proposed B. pinnipedialis, possessing 1 omp2a gene and 1 omp2b gene. Two field isolates revealed the presence of 2 omp2a genes, as has been described for Brucella ovis. To our knowledge, these results confirm for the first time the presence of Brucella species in the marine mammal population of the German North Sea. These findings highlight the need for additional research on the relevance of these Brucella species for marine hosts and their environment. 相似文献
14.
Eric Alfonsi Sami Hassani Fran?ois-Gilles Carpentier Jean-Yves Le Clec’h Willy Dabin Olivier Van Canneyt Michael C. Fontaine Jean-Luc Jung 《PloS one》2012,7(9)
Field surveys have reported a global shift in harbour porpoise distribution in European waters during the last 15 years, including a return to the Atlantic coasts of France. In this study, we analyzed genetic polymorphisms at a fragment of the mitochondrial control region (mtDNA CR) and 7 nuclear microsatellite loci, for 52 animals stranded and by-caught between 2000 and 2010 along the Atlantic coasts of France. The analysis of nuclear and mitochondrial loci provided contrasting results. The mtDNA revealed two genetically distinct groups, one closely related to the Iberian and African harbour porpoises, and the second related to individuals from the more northern waters of Europe. In contrast, nuclear polymorphisms did not display such a distinction. Nuclear markers suggested that harbour porpoises behaved as a randomly mating population along the Atlantic coasts of France. The difference between the two kinds of markers can be explained by differences in their mode of inheritance, the mtDNA being maternally inherited in contrast to nuclear loci that are bi-parentally inherited. Our results provide evidence that a major proportion of the animals we sampled are admixed individuals from the two genetically distinct populations previously identified along the Iberian coasts and in the North East Atlantic. The French Atlantic coasts are clearly the place where these two previously separated populations of harbour porpoises are now admixing. The present shifts in distribution of harbour porpoises along this coast is likely caused by habitat changes that will need to be further studied. 相似文献
15.
Ravi Bandara Dissanayake Emanuele Giorgi Mark Stevenson Rachel Allavena Joerg Henning 《Ecology and evolution》2021,11(20):13805
The koala, Phascolarctos cinereus, is an iconic Australian wildlife species facing a rapid decline in South‐East Queensland (SEQLD). For conservation planning, the ability to estimate the size of koala populations is crucial. Systematic surveys are the most common approach to estimate koala populations but because of their cost they are often restricted to small geographic areas and are conducted infrequently. Public interest and participation in the collection of koala sighting data is increasing in popularity, but such data are generally not used for population estimation. We modeled monthly sightings of koalas reported by members of the public from 1997 to 2013 in SEQLD by developing a self‐exciting spatio‐temporal point process model. This allowed us to account for characteristics that are associated with koala presence (which vary over both space and time) while accounting for detection bias in the koala sighting process and addressing spatial clustering of observations. The density of koalas varied spatially due to the heterogeneous nature of koala habitat in SEQLD, with a mean density of 0.0019 koalas per km2 over the study period. The percentage of land areas with very low densities (0–0.0005 koalas per km2) remained similar throughout the study period representing, on average, 66% of the total study area. The approach described in this paper provides a useful starting point to allow greater use to be made of incidental koala sighting data. We propose that the model presented here could be used to combine systematic koala survey data (which is spatially restricted, but more precise) with koala sighting data (which is incidental and often biased by nature, but often collected over large geographical areas). Our approach could also be adopted for modeling the density of other wildlife species where data is collected in the same manner. 相似文献
16.
Ruth H. Leeney Rachel Amies Annette C. Broderick Matthew J. Witt Jan Loveridge Joana Doyle Brendan J. Godley 《Biodiversity and Conservation》2008,17(10):2323-2338
Marine vertebrate strandings data can provide insights into the long-term dynamics of cetacean populations, and the threats
they face. We investigate whether the spatio-temporal patterns of cetacean strandings around Cornwall, SW Britain, have changed
in the past century. Analysis of strandings from 1911 to 2006 (n = 2,257) show that, since the mid-1970s, the relative frequency of strandings of common dolphins (Delphinus delphis), harbour porpoises (Phocoena phocoena) and pilot whales (Globicephala melas) has increased significantly. Seasonal peaks in strandings frequencies are apparent, between December and March for harbour
porpoises and common dolphins, and between November and January for pilot whales. There were significant positive trends in
the number of common dolphin and harbour porpoise strandings, as a proportion of total strandings, over time. Strandings of
common dolphins, porpoises and all other species occur more frequently on the south coast of Cornwall. A total of 415 cetaceans
were subject to full veterinary necropsy to determine cause of death, between 1990 and 2006, and 253 (61%) of these individuals
were determined to have died due to bycatch in fishing gear. Analyses of industrialised fishing pressure in UK waters show
the seas around Cornwall to be one of the most heavily fished areas of the UK. We suggest a number of factors that could be
responsible for the recent increases in cetacean strandings in southwest UK waters in recent years, including survey effort,
as well as abundance and range shifts that are potentially linked with climate change. Although detectable levels of bycatch
rate have not increased over time, fisheries interactions are in significant part responsible for mortality patterns and are
worthy of more detailed investigation.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
17.
Emiliano Manzo Paola Bartolommei J. Marcus Rowcliffe Roberto Cozzolino 《Acta theriologica》2012,57(2):165-172
Evaluating presence and abundance of small carnivores is essential for their conservation. In Italy, there is scarce information
on European pine marten distribution, and no data are published on its abundance. Camera traps have been widely used to estimate
population density applying capture–recapture models for species in which individual recognition is possible. Here we estimate
the abundance of European pine martens in central Italy using camera trapping and a model that allows the estimation of population
density without the need for individual recognition Rowcliffe et al. (Anim Conserv 11:185–186, 2008). Camera trapping was also used to evaluate habitat use patterns by martens. Fifteen camera traps were deployed in 90 placements
for 15 days each, for a total of 1,334 camera days. Pine martens were captured in 24% of camera trap placements with a mean
trap success rate of 0.33 photographs per camera placement. Estimated pine marten population density in the study area was
0.34 individuals km−2. Marten trap rate was not strongly associated with any habitat type, although there were trends towards lower probability
of records at locations with high coverage of cultivated fields and higher probability of records at locations with high coverage
of human-made woodland. The results suggest that pine martens in this area are not confined to wooded habitat. To our knowledge,
this study is the first application of the Rowcliffe et al. (Anim Conserv 11:185–186, 2008) method to a wild carnivore population and, furthermore, the first estimation of population density of pine martens in Italy. 相似文献
18.
K. Lehnert G. von Samson-Himmelstjerna C. Bleidorn U. Siebert 《International journal for parasitology》2010,40(7):845-853
Harbour porpoises (Phocoena phocoena) and harbour seals (Phoca vitulina) from German waters are infected by six species of lungworms (Metastrongyloidea). These nematodes parasitise the respiratory tract, are pathogenic and often cause secondary bacterial infections. In spite of their clinical and epidemiological significance, the life cycle and biology of lungworms in the marine environment is still largely unknown. Regions of ribosomal DNA (ITS-2) of all lungworms parasitising harbour porpoises and harbour seals in German waters were sequenced to characterise and compare the different species. The phylogenetic relationship among the lungworm species was analysed by means of their ITS-2 nucleotide sequences and the species-specific traits of the ITS-2 were used to screen wild fish as possible intermediate hosts for larval lungworms. Molecular markers were developed to identify larval nematodes via in-situ hybridisation of tissues of harbour porpoise and harbour seal prey fish. Potential wild intermediate fish hosts from the North Sea were dissected and found to harbour larval nematodes. Histological examination and in-situ hybridisation of tissue samples from these fish showed lungworm larvae within the intestinal wall. Based on larval ITS-2 nucleotide sequences, larval nematodes were identified as Pseudalius inflexus and Parafilaroides gymnurus. Turbot (Psetta maxima) bred and raised in captivity were experimentally infected with live L1s of Otostrongylus circumlitus and ensheathed larvae were recovered from the gastrointestinal tract of turbot and identified using molecular tools. Our results show that fish intermediate hosts play a role in the transmission of metastrongyloid nematodes of harbour porpoises and harbour seals. 相似文献
19.
Coastal protection measures are planned and executed worldwide to combat the effects of global warming and climate change, in particular the acceleration of sea level rise, higher storm surge flooding and extensive coastal inundation. The extent to which these defensive measures may impact coastal and estuarine ecosystems is still poorly understood. Since the building of a storm surge barrier, movement of harbour porpoises Phocoena phocoena in and out of the Eastern Scheldt tidal bay (SW-Netherlands) may be limited. To measure residency, porpoises stranded along the Dutch North Sea coast between 2006 and 2008 were sampled for muscle (n = 102) and bone tissue (n = 118), of which 9 muscle (8.8%) and 12 bone samples (10.2%) were collected from animals stranded within the Eastern Scheldt. Stable carbon (δ13C) was analysed to get insight into the habitat use and residency of porpoises in the Eastern Scheldt. Our data showed significantly higher δ13C values in the muscle of porpoises stranded within the Eastern Scheldt (µ = −17.7‰, SD = 0.4‰) compared to animals stranded along the Dutch coast (µ = −18.3‰, SD = 0.5‰). This suggests that most porpoises stranded in the Eastern Scheldt foraged there for a longer period. The distinct δ13C signature of animals from the Eastern Scheldt was not observed in bone tissue, suggesting a relatively recent shift in habitat use rather than life-long residency of porpoises within the Eastern Scheldt. The high number of strandings within the Eastern Scheldt suggests a higher mortality rate compared to the Dutch coastal zone. Our study indicates that along with other changes in the physical environment, the storm surge barrier may play an important role in determining the residency of porpoises in the Eastern Scheldt, and that the area might act as an ecological trap for porpoises entering it. 相似文献
20.
Estênio Guimar?es Paiva Chandra Salgado-Kent Marthe Monique Gagnon Iain Parnum Robert McCauley 《PloS one》2015,10(5)
Research involving marine mammals often requires costly field programs. This paper assessed whether the benefits of using cameras outweighs the implications of having personnel performing marine mammal detection in the field. The efficacy of video and still cameras to detect Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the Fremantle Harbour (Western Australia) was evaluated, with consideration on how environmental conditions affect detectability. The cameras were set on a tower in the Fremantle Port channel and videos were perused at 1.75 times the normal speed. Images from the cameras were used to estimate position of dolphins at the water’s surface. Dolphin detections ranged from 5.6 m to 463.3 m for the video camera, and from 10.8 m to 347.8 m for the still camera. Detection range showed to be satisfactory when compared to distances at which dolphins would be detected by field observers. The relative effect of environmental conditions on detectability was considered by fitting a Generalised Estimation Equations (GEEs) model with Beaufort, level of glare and their interactions as predictors and a temporal auto-correlation structure. The best fit model indicated level of glare had an effect, with more intense periods of glare corresponding to lower occurrences of observed dolphins. However this effect was not large (-0.264) and the parameter estimate was associated with a large standard error (0.113). The limited field of view was the main restraint in that cameras can be only applied to detections of animals observed rather than counts of individuals. However, the use of cameras was effective for long term monitoring of occurrence of dolphins, outweighing the costs and reducing the health and safety risks to field personal. This study showed that cameras could be effectively implemented onshore for research such as studying changes in habitat use in response to development and construction activities. 相似文献