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Despite threatened status, the Ganges River dolphin (Platanista gangetica) received insufficient attention in many habitats including the lower Ganges. In this study, through standardised monitoring programmes, we recorded the population and distribution of the species from a 100-km long stretch of the lower Ganges between January and December 2023. Important ecological parameters (e.g. fish abundance and water quality parameters) were also monitored to understand their effects on dolphin population in the river. Number of Ganges River dolphin varied over time (ANOVA: F11,88 = 10.9, p < 0.001) and space (F8,88 = 24.1, p < 0.001). Maximum number of dolphin was sighted in the month of August; whereas, the minimum was in February. Population of Ganges River dolphin was affected positively by fish abundance (LMM: F = 19.7, p < 0.001) and water transparency (F = 4.4, p = 0.042) and negatively by total dissolved solids (TDS; LMM: F = 13.5, p = 0.001). A range of challenges related to fishermen’s knowledge and attitude towards the Ganges River dolphin were identified. These include lack of awareness, high market demand and price for the species and negative attitude towards the species. Illegally harvested Vulnerable dolphins were sold only to produce dolphin oil to catch another Endangered fish species Clupisoma garua. The results of this study have conservation management applications and implications.

Traditionally, researchers have assessed diet selection by comparing consumed versus available taxa. However, taxonomic assignment is probably irrelevant for predators, who likely base their selection on characteristics including prey size, habitat, or behavior. Here, we use an aquatic insectivore, the threatened Pyrenean Desman (Galemys pyrenaicus), as a model species to assess whether biological traits help unravel the criteria driving food and habitat preferences. We reanalyzed data from a previous taxonomy-based study of prey selection in two contrasting streams, one with excellent conservation status and the other affected by diversion for hydropower and forestry. Available and consumed prey were characterized according to nine biological traits, and diet selection was estimated by comparing availability—measured from Surber net samples, and consumption—analyzed by metabarcoding desman feces. Traits offered a biologically coherent image of diet and almost identical selection patterns in both streams, depicting a highly specialized rheophilic predator. Desmans positively selected prey with a preference for fast flow and boulder substrate, indicating their preferred riffle habitat. On the other hand, they positively selected prey with larger but not the largest potential size, living in the water column or the litter, and not inside sediments. They also chose agile prey, swimmers or prey attached to the substrate, prey with high body flexibility, and prey living exposed and clustered in groups. Overall, our results offer a picture of desman diet preference and point to biological traits as being better than taxonomic identity to describe the diet preference of consumers. [ABSTRACT FROM AUTHOR]

Although gut microbes are regarded as a significant component of many mammals and play a very important role, there is a paucity of knowledge around marine mammal gut microbes, which may be due to sampling difficulties. Moreover, to date, there are very few, if any, reports on the gut microbes of melon-headed whales. In this study, we opportunistically collected fecal samples from eight stranded melon-headed whales (Peponocephala electra) in China. Using high-throughput sequencing technology of partial 16S rRNA gene sequences, we demonstrate that the main taxa of melon-headed whale gut microbes are Firmicutes, Fusobacteriota, Bacteroidota, and Proteobacteria (Gamma) at the phylum taxonomic level, and Cetobacterium, Bacteroides, Clostridium sensu stricto, and Enterococcus at the genus taxonomic level. Meanwhile, molecular ecological network analysis (MENA) shows that two modules (a set of nodes that have strong interactions) constitute the gut microbial community network of melon-headed whales. Module 1 is mainly composed of Bacteroides, while Module 2 comprises Cetobacterium and Enterococcus, and the network keystone genera are Corynebacterium, Alcaligenes, Acinetobacter, and Flavobacterium. Furthermore, by predicting the functions of the gut microbial community through PICRUSt2, we found that although there are differences in the composition of the gut microbial community in different individuals, the predicted functional profiles are similar. Our study gives a preliminary inside look into the composition of the gut microbiota of stranded melon-headed whales. [ABSTRACT FROM AUTHOR]

Conservation of freshwater biodiversity and management of human-wildlife conflicts are major conservation challenges globally. Human-wildlife conflict occurs due to attacks on people, depredation of fisheries, damage to fishing equipment and entanglement in nets. Here we review the current literature on conflicts with tropical and subtropical crocodilians, cetaceans and otters in freshwater and brackish habitats. We also present a new multispecies case study of conflicts with four freshwater predators in the Western Amazon: black caiman (Melanosuchus niger), giant otter (Pteronura brasiliensis), boto (Inia geoffrensis) and tucuxi (Sotalia fluviatilis). Documented conflicts occur with 34 crocodilian, cetacean and otter species. Of the species reviewed in this study, 37.5% had conflicts frequently documented in the literature, with the saltwater crocodile (Crocodylus porosus) the most studied species. We found conflict severity had a positive relationship with species body mass, and a negative relationship with IUCN Red List status. In the Amazonian case study, we found that the black caiman was ranked as the greatest 'problem' followed by the boto, giant otter and tucuxi. There was a significant difference between the responses of local fishers when each of the four species were found entangled in nets. We make recommendations for future research, based on the findings of the review and Amazon case study, including the need to standardise data collection. [ABSTRACT FROM AUTHOR]

Although gut microbes are regarded as a significant component of many mammals and play a very important role, there is a paucity of knowledge around marine mammal gut microbes, which may be due to sampling difficulties. Moreover, to date, there are very few, if any, reports on the gut microbes of melon-headed whales. In this study, we opportunistically collected fecal samples from eight stranded melon-headed whales (Peponocephala electra) in China. Using high-throughput sequencing technology of partial 16S rRNA gene sequences, we demonstrate that the main taxa of melon-headed whale gut microbes are Firmicutes, Fusobacteriota, Bacteroidota, and Proteobacteria (Gamma) at the phylum taxonomic level, and Cetobacterium, Bacteroides, Clostridium sensu stricto, and Enterococcus at the genus taxonomic level. Meanwhile, molecular ecological network analysis (MENA) shows that two modules (a set of nodes that have strong interactions) constitute the gut microbial community network of melon-headed whales. Module 1 is mainly composed of Bacteroides, while Module 2 comprises Cetobacterium and Enterococcus, and the network keystone genera are Corynebacterium, Alcaligenes, Acinetobacter, and Flavobacterium. Furthermore, by predicting the functions of the gut microbial community through PICRUSt2, we found that although there are differences in the composition of the gut microbial community in different individuals, the predicted functional profiles are similar. Our study gives a preliminary inside look into the composition of the gut microbiota of stranded melon-headed whales.

Morphological data are used to describe a new nematode species, Heterocheilus floridensis sp. n. (Heterocheilidae) from the digestive tract of the Florida manatee Trichechus manatus latirostris (Harlan) (Trichechidae, Sirenia) from Florida, USA. Examination by light and scanning electron microscopy revealed that the new species differs from the related Heterocheilus tunicatus Diesing, 1839 mainly by having dentigerous ridges on the inner surface of the lips, a median unpaired papilla located anterior to the cloaca, and a considerably larger body size. Sequence data for subunits I and II of mitochondrial cytochrome oxidase gene, 18S small subunit and 28S ribosomal RNA genes were provided for molecular characterisation of the new species. However, the current unavailability of homologous sequence data for congeneric specimens precluded a molecular assessment of the morphological species hypothesis, and ascaridoid phylogenetic hypotheses could not be advanced. Specimens of Heterocheilus sp. collected from the Antillean manatee Trichechus manatus manatus Linnaeus in Puerto Rico, on loan from the US National Museum of Natural History, were morphologically consistent with the new species, so apparently all congeneric nematodes reported from both subspecies of the West Indian manatee Trichechus manatus Linnaeus and previously identified as H. tunicatus belong rather to H. floridensis sp. n. Heterocheilus hagenbecki (Khalil et Vogelsang, 1932) Sprent 1980 is here considered to be a species inquirenda. A key to valid species of Heterocheilus Diesing, 1839 is provided.

We assessed the feeding habits of the Amazonian manatee inhabiting blackwater (Negro River) and clearwater (Tapajós River) igapós (floodplains) using δ13C and δ15N of dentin and bone collagen from different ontogenetic classes (nursing calves, juveniles, and adults). Within an individual, the dentine δ13C and δ15N values did not vary with tooth position. Bones were more depleted in 13C and 15N compared to teeth, and the δ13C and δ15N in bone differed among classes. Food sources had δ13C values typical of algae, plants of C3 or C4 photosynthetic pathways. Mixing models showed that lactating females (inferred by isotopic values from nursing calves) had higher proportional consumption of C4 plants, while, for other adults, C3 plants were more frequent in the diet of manatees from both rivers. Juveniles had a mixed diet of C3 pants and C4 plants. We hypothesize the C4 plants signal of calves results from female movements to the floodplains of nearby whitewater rivers (várzeas), where C4 plants are abundant. Individuals from Tapajós may be more resident, as C3 plants and C4 plants are available during the flood pulse. Results demonstrate that manatee diets vary with ontogenetic classes and water typology. Preservation of habitats (igapó/várzea) is therefore required for the survival of Amazonian manatees. [ABSTRACT FROM AUTHOR]

The aim of this study was to present a first case of fibro-purulent pneumonia and chronic kidney disease in the Antillean manatee. The 23-yr-old female of Antillean manatee (Therese von Bayern) was moved from the Tierpark Berlin (Germany) to the Wroclaw Zoological Garden (Poland), on the 15th of December 2014. The manatee died on the 4th of April 2015. Postmortem examination revealed the right lung dark red lesions indicative of pulmonary congestion and extravasations. There was a fist-sized cavity filled with a bloody fluid and fragments of lung tissue at onethird of the length of that lung. Both kidneys with no pathologic changes, pale pink, with fragile structure. Histopathologic examination revealed fibro-purulent bronchopneumonia, interstitial renal fibrosis, nephritis and glomerulonephritis with protein deposits and acute tubular necrosis (ATN), hepatic fibrosis and hepatocellular degeneration. The lung tissue expressed cytokeratin, vimentin and a CD68 macrophage marker. [ABSTRACT FROM AUTHOR]

A group of Smooth-coated otter (Lutrogale perspicillata GEOFFROY 1826) was sighted at Gavier lake of Nature Club Surat. This group of otter was documented by Nature Club Surat with the help of camera traps. Nature Club Surat has also identified five other sites where indirect signs of otters were found. In March 2014 otters were sighted for the first time in Gavier Lake but no photographic evidences were found at that time. (http://timesofindia.indiatimes.com/city/surat/Endangered-otters-back-in-Gavierlake/ articleshowprint/31931076.cms?null). According to presently available data and information of Gujarat State Forest Department, smooth-coated otters are only found in Narmada River system and surrounding water sources such as wetlands, lakes, canals and streams. [ABSTRACT FROM AUTHOR]

Between September 2001 and March 2013, 62 bacterial cultures (37 aerobic and 25 anaerobic) were performed on 37 blood samples from 23 Antillean manatees ( Trichechus manatus manatus) that were kept in captivity at the Brazilian National Center for Research and Conservation of Aquatic Mammals (CMA) in Pernambuco (CMA-PE) and Alagoas (CMA-AL), Brazil. All of the animals sampled exhibited clinical signs at the time of sampling including abscesses ( n = 8), debilitation and anorexia ( n = 22), and profound lethargy-moribundity ( n = 7). The 4 animals with profound lethargy-moribundity died shortly after sampling of unknown causes. Bacteria were isolated from 15/37 (40.5%) and aerobic blood cultures from 13/23 animals (56.5%). None of the anaerobic cultures were positive. Aeromonas caviae, Aeromonas hydrophila, Aeromonas sp., Escherichia coli, Leclercia adecarboxylata, Pantoea agglomerans, Pseudomonas aeruginosa, Pseudomonas stutzeri, Pseudomonas sp., Sphingomonas paucimobilis, coagulase-negative Staphylococcus, and Staphylococcus epidermidis were each found in only one animal; Staphylococcus spp. was found in two; and Vibrio fluvialis in four. Thirteen samples had only one bacteria isolated, one sample had two bacteria, and one sample had three bacteria isolated. Regarding sex, age group, and origin among the manatees examined, 54.5% (6/11) of the females, 58.3% (7/12) of the males, 40% (2/5) of the calves, 66.7% (8/12) of the juveniles, 50% (3/6) of the adults, 55.5% (10/18) at CMA-PE, and 60% (3/5) at CMA-AL were found to be positive for bacterial growth during at least one sampling time. All Antillean manatees were clinically ill. Regarding clinical signs, bacteria were found in 50% (11/22) of blood samples of the animals showing debilitation and anorexia, 1 of 8 (12.5%) of blood samples of the animals showing abscesses, and 3 of 7 (42.9%) of blood samples of the animals showing profound lethargy-moribundity. [ABSTRACT FROM AUTHOR]

Com o objetivo de testar o tempo de passagem do alimento no trato digestório de peixes-bois da Amazônia em cativeiro, foram testadas separadamente duas dietas distintas. Uma composta exclusivamente de capim do gênero Brachiaria (dieta experimental - DE 1) e outra de capim do gênero Brachiaria acrescentado de pequenas porções de ração extrusada para eqüinos (dieta experimental - DE 2). Foram selecionados do plantel do INPA dois animais adultos machos sadios, os quais foram isolados dos demais e submetidos a um período de aclimatação às dietas experimentais por 15 dias. Após este período, as dietas foram marcadas com uma fita plástica de 10 cm e fornecidas aos animais que foram monitorados em intervalos de uma hora. Todo material fecal foi coletado até a recuperação dos marcadores plásticos. A média do tempo de passagem da DE 1 foi de 123h57min, cerca de 5,15 dias e da DE 2 foi de 125h04min ou 5,21 dias. Não houve diferença estatística (PThe objective of this study was to determine the transit time of two diets in the digestive tract of the Amazonian manatee in captivity. We tested separately two different diets: one composed exclusively of grass of the genus Brachiaria (experimental diet - ED- A 1) and the other composed of grass Brachiaria added with small portions of extruded pellets for horses (experimental diet ED- A 2). Two healthy adult manatees were selected and isolated from the rest and underwent a period of food acclimation with the experimental diets for 15 days. After this period, the experimental diet was marked with a plastic colored tape of 10-cm length and given to the animals. The manatees were monitored at intervals of 1 hour and all fecal material was collected until recovery of the markers. The mean transit time of ED - A1 was 123h57min , about 5.16 days and ED - A 2 was 125h04min or 5.21 days. There was no statistical difference (P

This study aimed to identify the diet of giant otters, Pteronura brasiliensis (Zimmermann, 1780) in the Balbina reservoir (01º55'S, 59º29'W), to compare it with literature data on the diet of giant otters from non-dammed areas, and to verify the effects of the seasonal changes in water levels on the feeding habits of Balbina otters. A total of 254 feces samples were collected and identified according to the lowest possible taxonomic level. Teleostei fish were present in 100% of the samples; two samples also presented monkey fur (n = 1) and sloth fur (n = 1), suggesting that the diet of P. brasiliensis, in the reservoir, is almost exclusively based on fish. Ten fish families were identified in our samples, six of which were exclusive to the Balbina Lake (not present in the diet of giant otters from non-dammed areas). These six fish families, however, were present in less than 3% of the samples. The fish families with highest representation in the diet of giant otters from non-dammed areas also appeared with higher frequencies in the Balbina Lake, suggesting that the otters have not changed their diet substantially after the implementation of the reservoir. During the high-water period, when the fish are dispersed into the flooded forest and are not very easy to catch, the otters seem to have an opportunistic feeding habit. By contrast, during the low-water period, when prey items are widely available and easier to catch in the reservoir, their feeding habits are more selective.

The Antillean manatee (Trichechus manatus manatus) is now considered to be the most endangered aquatic mammal of Brazil. During 1992 and 1993, we surveyed 3000km of the coastal area of the Maranhão (MA), Pará (PA) and Amapá (AP) states where we visited 145 localities and performed 262 interviews aiming to identify the hunting pressure on the species, and how the population actually uses the manatees hunted on the Brazilian north coast. The people interviewed were involved in fishing activities, preferably those who hunted manatees. Catches followed by intentional killing were responsible for 94.07% of the cases of mortality, while animals stranded on the beach represented 5.93% of the cases. Intentional capture was the strongest factor in the manatee mortality, and hunting with a harpoon occurred in 86.38% of catches. After capture, the animals were used for the hunter’s subsistence (63.83%) and human consumption and trading (30.64%), and the animals’ parts were used for diverse purposes (medicine, fetish and santerias). It was considered that a proper understanding of the communities’ customs concerning the animals was important for any proposal of conservation strategies.

This study aimed to elucidate the catalytic function of cytochrome P450 (CYP) 1 enzymes in aquatic mammals. Alkoxyresorufin O -dealkylation (AROD) activities including methoxy- (MROD), ethoxy- (EROD), pentoxy- (PROD), and benzyloxyresorufin O -dealkylation (BROD), and 2- and 4-hydroxylation activities of 17β-estradiol (E 2 ) were measured by using yeast-expressed Baikal seal ( Pusa sibirica ) CYP1A1, 1A2, and 1B1 proteins. Heterologous protein expression of the Baikal seal CYP1s (bsCYP1s) in yeast microsomes was confirmed by reduced CO-difference spectra and immunoblotting. Heterologously expressed human CYP1 enzyme (hCYP1) activities were simultaneously measured and compared with those of bsCYP1 isozymes. Recombinant bsCYP1A1 protein showed the highest V max of EROD, followed by MROD, PROD, and BROD, similar to that of hCYP1A1. V max / K m ratios of all AROD activities catalyzed by bsCYP1A1 were lower than those catalyzed by hCYP1A1, suggesting less potential for AROD by bsCYP1A1. Enzymatic assays for bsCYP1A2 showed no or minimal AROD activities, while hCYP1A2 displayed MROD and EROD activities. bsCYP1B1 showed an AROD profile (EROD > BROD > MROD >> PROD) similar to that of hCYP1B1; however, V max / K m ratios of all AROD activities by bsCYP1B1 were higher. Yeast microsomes containing bsCYP1A1 and 1B1 and hCYP1A1, 1A2, and 1B1 metabolized E 2 to 2-OHE 2 and 4-OHE 2 , whereas bsCYP1A2 showed no such activity. Comparison of 4- and 2-hydroxylations of E 2 by CYP1As suggests that bsCYP1A1, hCYP1A1, and 1A2 preferentially catalyze 2- rather than 4-hydroxylation. As for CYP1B1, the V max / K m ratios suggest that both Baikal seal and human CYPs catalyze 4- rather than 2-hydroxylation. Interspecies comparison showed that bsCYP1B1 has higher metabolic potencies for both E 2 hydroxylations than does hCYP1B1, whereas the activity of bsCYP1A1 was lower than that of hCYP1A1. Messenger RNA expression levels of bsCYP1s in the liver of Baikal seals indicated that bsCYP1A1 and 1A2 enzymes contributed to 16.2% and 83.7% of total CYP1s, respectively; bsCYP1B1 accounted for only 0.06%. Addition of anti-human CYP1A1 antibody in seal liver microsomes suppressed EROD activity more than did anti-human CYP1A2 antibody. Therefore, EROD may be catalyzed by hepatic bsCYP1A1 but not bsCYP1A2, consistent with the results of yeast-expressed bsCYP1A1 and 1A2. In silico substrate-docking models of bsCYP1s suggested that the defect in bsCYP1A2 enzymatic activities may be accounted for by the Pro substitution of highly conserved Thr in the I-helix, which is involved in formation of a hydrogen bond with the hydroperoxy intermediate on the heme. This Thr-Pro substitution is evolutionarily conserved across aquatic mammals and could explain their lower metabolic potential for persistent organic pollutants. [ABSTRACT FROM AUTHOR]

Background: Which factors influence the distribution patterns of morphological diversity among clades? The adaptive radiation model predicts that a clade entering new ecological niche will experience high rates of evolution early in its history, followed by a gradual slowing. Here we measure disparity and rates of evolution in Carnivora, specifically focusing on the terrestrial-aquatic transition in Pinnipedia. We analyze fissiped (mostly terrestrial, arboreal, and semi-arboreal, but also including the semi-aquatic otter) and pinniped (secondarily aquatic) carnivorans as a case study of an extreme ecological transition. We used 3D geometric morphometrics to quantify cranial shape in 151 carnivoran specimens (64 fissiped, 87 pinniped) and five exceptionally-preserved fossil pinnipeds, including the stem-pinniped Enaliarctos emlongi. Range-based and variance-based disparity measures were compared between pinnipeds and fissipeds. To distinguish between evolutionary modes, a Brownian motion model was compared to selective regime shifts associated with the terrestrial-aquatic transition and at the base of Pinnipedia. Further, evolutionary patterns were estimated on individual branches using both Ornstein-Uhlenbeck and Independent Evolution models, to examine the origin of pinniped diversity. Results: Pinnipeds exhibit greater cranial disparity than fissipeds, even though they are less taxonomically diverse and, as a clade nested within fissipeds, phylogenetically younger. Despite this, there is no increase in the rate of morphological evolution at the base of Pinnipedia, as would be predicted by an adaptive radiation model, and a Brownian motion model of evolution is supported. Instead basal pinnipeds populated new areas of morphospace via low to moderate rates of evolution in new directions, followed by later bursts within the crown-group, potentially associated with ecological diversification within the marine realm. Conclusion: The transition to an aquatic habitat in carnivorans resulted in a shift in cranial morphology without an increase in rate in the stem lineage, contra to the adaptive radiation model. Instead these data suggest a release from evolutionary constraint model, followed by aquatic diversifications within crown families. [ABSTRACT FROM AUTHOR]

Prey preference of the North American river otter (Lontra canadensis) was studied in a captive population and evaluated according to optimal foraging theory. Live sunfish (Lepomis spp.), brown trout (Salmo trutta), and crayfish (Cambaridae spp.) were released in a pool, and the search, chase, and handling/eating times of two otters were recorded. When provided with choice of sizes, otters showed a significant preference for catching and eating large prey first. When given a choice of species, otters significantly preferred to catch and eat brown trout first; this preference remained when offered dead prey. Using the rate of energy intake, the preference for brown trout was expected as it provided significantly more energy per unit time, but size preferences only fit predictions after metabolic rate was incorporated, as an otter expends more energy chasing prey in the water than when eating on land. The net energy gained was significantly greatest for large prey in all the size trials and for brown trout in the species trials. Captive river otters exhibit prey preferences that match our predictions based on optimal foraging theory, which can provide insight into dietary habits of wild otter populations. [ABSTRACT FROM AUTHOR]

Passive electroreception is a sensory modality in many aquatic vertebrates, predominantly fishes. Using passive electroreception, the animal can detect and analyze electric fields in its environment. Most electric fields in the environment are of biogenic origin, often produced by prey items. These electric fields can be relatively strong and can be a highly valuable source of information for a predator, as underlined by the fact that electroreception has evolved multiple times independently. The only mammals that possess electroreception are the platypus ( Ornithorhynchus anatinus) and the echidnas (Tachyglossidae) from the monotreme order, and, recently discovered, the Guiana dolphin ( Sotalia guianensis) from the cetacean order. Here we review the morphology, function and origin of the electroreceptors in the two aquatic species, the platypus and the Guiana dolphin. The morphology shows certain similarities, also similar to ampullary electroreceptors in fishes, that provide cues for the search for electroreceptors in more vertebrate and invertebrate species. The function of these organs appears to be very similar. Both species search for prey animals in low-visibility conditions or while digging in the substrate, and sensory thresholds are within one order of magnitude. The electroreceptors in both species are innervated by the trigeminal nerve. The origin of the accessory structures, however, is completely different; electroreceptors in the platypus have developed from skin glands, in the Guiana dolphin, from the vibrissal system. [ABSTRACT FROM AUTHOR]

Abstract: The use of transthoracic echocardiography in dolphins has been limited so far owing to technical and anatomical specificities. Anatomic M-mode (AMM) is a postprocessing echocardiographic technique generating M-mode studies from two-dimensional (2D) cineloops independently of the ultrasound beam orientation. The aim of the present study was to determine the within-day (repeatability) and between-day (reproducibility) variability of AMM echocardiography in awake healthy bottlenose dolphins (BN, Tursiops truncatus). Four adult BN trained to lie in left recumbency at the water surface were involved in the protocol. A total of 96 echocardiographic examinations were performed on 4 different days by a trained observer examining each BN 6 times per day. Video clips of 2D left parasternal long-axis views showing the left ventricle (LV) ventrally and the aortic root dorsally were recorded at each examination and analyzed for AMM measurements in a random order. A general linear model was used to determine the within-day and between-day coefficients of variation (CV). All examinations were interpretable allowing calculation of 10 AMM variables (i.e., end-diastolic and end-systolic ventral and dorsal LV myocardial wall thicknesses as well as LV and aortic diameters, mean aortic diameter, and LV shortening fraction). Most within- and between-day CV values (18/20) were <15%, the lowest being observed for the end-diastolic LV diameter (1.6%). In conclusion, AMM provides a simple non-invasive evaluation of heart morphology and function in the awake BN with good repeatability and reproducibility of the measurements. Further studies are required to determine the corresponding reference intervals. [Copyright &y& Elsevier]

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During the past 50 years, the high acoustic sensitivity and the echolocation behavior of dolphins and other small odontocetes have been studied thoroughly. However, understanding has been scarce as to how the dolphin cochlea is stimulated by high frequency echoes, and likewise regarding the ear mechanics affecting dolphin audiograms. The characteristic impedance of mammalian soft tissues is similar to that of water, and thus no radical refractions of sound, nor reflections of sound, can be expected at the water/soft tissue interfaces. Consequently, a sound-collecting terrestrial pinna and an outer ear canal serve little purpose in underwater hearing. Additionally, compared to terrestrial mammals whose middle ear performs an impedance match from air to the cochlea, the impedance match performed by the odontocete middle ear needs to be reversed to perform an opposite match from water to the cochlea. In this paper, we discuss anatomical adaptations of dolphins: a lower jaw collecting sound, thus replacing the terrestrial outer ear pinna, and a thin and large tympanic bone plate replacing the tympanic membrane of terrestrial mammals. The paper describes the lower jaw anatomy and hypothetical middle ear mechanisms explaining both the high sensitivity and the converted acoustic impedance match. [ABSTRACT FROM AUTHOR]

The diet of the platypus Ornithorhynchus anatinus was studied by examination of material collected from the cheek pouches of animals captured while foraging in streams in Kangaroo Valley, NSW, Australia. Platypuses consumed benthic invertebrates from 55 families in 16 orders, with virtually no prey being derived from the terrestrial environment. We also sampled invertebrates in pool, riffle and stream edge habitats to identify where prey were obtained. Invertebrates in the diet were most similar to those collected along stream edges and in pools compared with the faster-flowing riffles, suggesting that platypuses focused their foraging activities largely in these deeper water habitats. Although there was no seasonality in the assemblage structure of macroinvertebrates, the diet of platypuses varied between seasons, notably between winter and summer, suggesting that some dietary selectivity is seasonal. Dietary differences between the sexes were not detected. Overall, our results suggest that some dietary selection occurs in the platypus with respect to both foraging habitat and season. Seasonal selectivity may reflect different metabolic demands on platypuses at different times of the year. In contrast, habitat selectivity may reflect difficulty of prey access and risk of prey escape in fast-flowing riffles, higher energy costs and risk of predation associated with exploiting this habitat, and prey avoidance responses that are more rapid in the shallow riffles than in the deeper water pools and stream edges. These alternatives await evaluation by future research. [ABSTRACT FROM AUTHOR]

Mink ( Mustela vison) carcasses were collected from local commercial trappers from fall 1998 to spring 2003 from tributaries and marshes within 4.8km from the shores of Lakes Erie and St. Clair, including the Wheatley Harbour and St. Clair River Areas of Concern (AOCs), as well as from inland sites (8 to 40km from shore). Liver concentrations, on a lipid weight basis, of chlorinated hydrocarbons were measured and compared among sites and to tissue concentrations of mink from two previous collections from similar sites over the past 25 years. Mink from the western Lake Erie sites, which included the Wheatley Harbour AOC, had significantly higher concentrations of sum PCBs and PCB Aroclors than those from the St. Clair corridor or inland sites, with concentrations from the rest of Lake Erie being intermediate. Dieldrin concentrations were also significantly higher in western Lake Erie than many other sites, and those of oxychlordane and mirex also tended to be higher (0.05 < p < 0.1). There were no differences in contaminant concentrations between the St. Clair River AOC and the downstream non-AOC Lake St. Clair site, with the exception of slightly higher levels of octachlorostyrene (OCS). Concentrations of PCBs and other chlorinated hydrocarbons in mink showed a general decrease over the past two decades. In contrast, PCBs and some organochlorine pesticides tended to increase, significantly so with oxychlordane, in western Lake Erie mink over the same time period. DDE declined at all sites. Currently, mink liver PCB concentrations are within the range associated with reproductive impairment, as determined from captive mink studies, in 11.7% of all animals collected from the Lakes Erie and St. Clair basin overall, but in almost 40% of individuals from western Lake Erie. [ABSTRACT FROM AUTHOR]

In South Carolina, U.S.A., mink have been reintroduced from two apparently healthy populations to areas where populations have existed in the past but have been extirpated. High mortality was observed during transport of mink from the source populations. In order to elucidate the potential effects of dioxin-like compounds on the survival and reproduction of mink, concentrations of total polychlorinated biphenyls (PCBs), p,p′-DDE, dioxin-like PCBs, polychlorinated dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs) were measured in livers of mink collected from the source populations in South Carolina and Louisiana. Concentrations of total 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) for the South Carolina and Louisiana mink were 21 and 14 pg g-1, wet wt., respectively. PCB and TEQ concentrations were close to the threshold values that can, under laboratory conditions, elicit toxic effects in ranch mink. Therefore, any additional exposures of these populations to TEQs might adversely affect their populations. [ABSTRACT FROM AUTHOR]