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ABSTRACT Transmitting biosonar clicks and auditory evoked potential (AEP) responses triggered by the clicks were synchronously recorded during echolocation in an Atlantic bottlenose dolphin (Tursiops truncatus) trained to wear suction-cup... more
ABSTRACT Transmitting biosonar clicks and auditory evoked potential (AEP) responses triggered by the clicks were synchronously recorded during echolocation in an Atlantic bottlenose dolphin (Tursiops truncatus) trained to wear suction-cup EEG electrodes and to detect targets by echolocation. Three targets with target strengths of 34, 28 and 22 dB were used at a target distance of 2 to 6.5 m for each target. The results demonstrated that the AEP appeared to both transmitting echolocation clicks and echoes during echolocation, with AEP complexes consisting of alternative positive and negative waves. The echo-related AEP amplitudes were obviously lower than the transmitting click-related AEP amplitudes for all the targets at the investigated target distances. However, for targets with target strengths of 22 and 28 dB, the echo-related AEP response amplitudes increased at further target distances, demonstrating an overcompensation of echo attenuation with target distance in the echo-perception system of the dolphin biosonar. Measurement and analysis of transmitting click intensities showed that the click levels increased with target distance (R). The results demonstrated that a dual-component biosonar control system formed by intensity compensation behavior in both the transmission and receiving phases of a biosonar cycle exists synchronously in the dolphin biosonar system.
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Dugongs ( Dugong dugon ) experienced a serious population decline in China during the twentieth century, and their regional status is poorly understood. To determine their current distribution and status, we conducted a large-scale... more
Dugongs ( Dugong dugon ) experienced a serious population decline in China during the twentieth century, and their regional status is poorly understood. To determine their current distribution and status, we conducted a large-scale interview survey of marine resource users across four Chinese provinces and reviewed all available historical data covering the past distribution of dugongs in Chinese waters. Only 5% of 788 respondents reported past dugong sightings, with a mean last-sighting date of 23 years earlier, and only three respondents reported sightings from within the past 5 years. Historical records of dugongs peak around 1960 and then decrease rapidly from 1975 onwards; no records are documented after 2008, with no verified field observations after 2000. Based on these findings, we are forced to conclude that dugongs have experienced rapid population collapse during recent decades and are now functionally extinct in China. Our study provides evidence of a new regional loss o...
Immunization with peptides derived from apolipoprotein B-100 (ApoB-100) has been shown to ameliorate atherosclerosis in apolipoprotein E knockout (ApoE-/-) mice. However, the exact mechanism underlying the therapeutic effects remains... more
Immunization with peptides derived from apolipoprotein B-100 (ApoB-100) has been shown to ameliorate atherosclerosis in apolipoprotein E knockout (ApoE-/-) mice. However, the exact mechanism underlying the therapeutic effects remains elusive. To shed light on this mechanism, we immunized ApoE-/- mice that were fed a Western diet with either malondialdehyde-modified ApoB-100 peptide 210 (P210) emulsified in Freund's adjuvant or anti-malondialdehyde-modified P210 antibody (P210-Ab). Mice immunized with Freund's adjuvant or bovine serum albumin served as controls. Macrophages were incubated in vitro with oxidized low-density lipoprotein (ox-LDL) or ox-LDL plus P210-Ab. Our results show that P210-Ab promoted cholesterol efflux, inhibited lipid accumulation in vitro, and reduced plasma levels of high-sensitivity C-reactive protein (hsCRP), monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6). Furthermore, dramatically increased...
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In this paper, we propose a block sparsity-based method to reconstruct marine mammal whistle calls. Considering the block structure of harmonic chirp, we form an overcomplete group chirp dictionary to enhance the estimating resolution... more
In this paper, we propose a block sparsity-based method to reconstruct marine mammal whistle calls. Considering the block structure of harmonic chirp, we form an overcomplete group chirp dictionary to enhance the estimating resolution under iterative greedy approach. The resulting sparse estimator, also named Block Orthogonal Matching Pursuit based Discrete Chirp Fourier Transform (Block-OMP based DCFT), is able to achieve an acceptable estimating result in a noisy environment. We illustrate the performance of the resulting estimator using both simulated and collected dolphin whistles.
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The currently recognized Indo-Pacific humpback dolphin occurs in estuaries and surrounding shallow waters from the South China Sea to the Asian coast of the Indian Ocean. However, a recent study suggested that the humpback dolphin from... more
The currently recognized Indo-Pacific humpback dolphin occurs in estuaries and surrounding shallow waters from the South China Sea to the Asian coast of the Indian Ocean. However, a recent study suggested that the humpback dolphin from the Bay of Bengal may represent a distinct phylogenetic species. In this study, we sequenced 915-bp mtDNA segments from five geographic populations in both Chinese and Thai waters; together with previously published sequences, these data revealed that the ancestral Indo-Pacific humpback dolphin might have split during the transition from the Oligocene to Miocene (23.45 Mya, 95% HPD: 16.65 - 26.55 Mya), and then dispersed along the Pacific and Indian Ocean coasts of Asia. Genetic differentiation was detected between most of the examined populations, except for only a few pairwise populations in the northern South China Sea. Genetic differentiation/distance between the humpback dolphins from the northern and southern South China Sea met the sub-species threshold value proposed for marine mammals, whereas that between the humpback dolphins in the Pacific and the Indian Ocean was above the species threshold. Bayesian inference of historic gene flow indicated low but constant northward gene flow along the Indian Ocean coast; however, there was a recent abrupt increase in gene flow in the Pacific region, likely due to the shortening coastline at the low stand of sea level. Our results revealed that the current taxonomic classification of Indo-Pacific humpback dolphins may not reflect their phylogeography. This article is protected by copyright. All rights reserved.
Research Interests: Zoology and Indo Pacific
Beaked whales represent around 25% of known extant cetacean species, yet they are the least known of all marine mammals. Identification of many Mesoplodon species has relied on examination of a few stranded individuals. Particularly, the... more
Beaked whales represent around 25% of known extant cetacean species, yet they are the least known of all marine mammals. Identification of many Mesoplodon species has relied on examination of a few stranded individuals. Particularly, the ginkgo-toothed beaked whale (Mesoplodon ginkgodens) and Deraniyagala's beaked whale (Mesoplodon hotaula) are among the least-known of beaked whale species, without confirmed sightings of living individuals to date. We present a sighting of three free-ranging individuals of M. ginkgodens / hotaula whale from a dedicated marine mammal vessel survey carried out in the South China Sea in April and May 2019. Photographic data (301 photographs) from the sighting were compared to photos of fresh stranded ginkgo-toothed beaked whale and Deraniyagala's beaked whale from both historical and unpublished records. We found that free-ranging M. gingkodens and M. hotaula individuals can be easily distinguished from other Mesoplodon species due to differences in melon and gape shapes and coloration patterns. However, accurate at-sea differentiation of M. ginkgodens and M. hotaula may not be possible due to high similarity in both coloration and scarring patterns. In addition to our photo-identification data, we collected what we believe to be the first preliminary descriptions of surfacing behavior and diving patterns of one of these species. Finally, the presence of scars possibly caused by fishing gear or marine litter raises concerns about anthropogenic impacts and conservation of these poorly-known species. This article is protected by copyright. All rights reserved.
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The underwater soundscape is an important ecological element affecting numerous aquatic animals, in particular dolphins, which must identify salient cues from ambient ocean noise. In this study, temporal variations in the soundscape of... more
The underwater soundscape is an important ecological element affecting numerous aquatic animals, in particular dolphins, which must identify salient cues from ambient ocean noise. In this study, temporal variations in the soundscape of Jiaotou Bay were monitored from February 2016 to January 2017, where a population of Indo-Pacific humpback dolphins (Sousa chinensis) has recently been a regular sighting. An autonomous acoustic recorder was deployed in shallow waters, and 1/3-octave band sound pressure levels (SPLs) were calculated with central frequencies ranging from 25 Hz to 40 kHz, then were grouped into 3 subdivided bands via cluster analysis. SPLs at each major band showed significant differences on a diel, fishing-related period, seasonal, and tidal phase scale. Anthropogenic noise generated by passing ships and underwater explosions were recorded in the study area. The fish and dolphin acoustic activities both exhibited diel and seasonal variations, but no tidal cycle patterns. A negative significant relationship between anthropogenic sound detection rates and dolphin detection rates were observed, and fish detection rates showed no effect on dolphin detection rates, indicating anthropogenic activity avoidance and no forced foraging in dolphins in the study area. The results provide fundamental insight into the acoustic dynamics of an important Indo-Pacific humpback dolphin habitat within a coastal area affected by a rapid increase in human activity, and demonstrate the need to protect animal habitat from anthropogenic noises.
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Despite an increasing appreciation in the importance of host–microbe interactions in ecological and evolutionary processes, information on the gut microbial communities of some marine mammals is still lacking. Moreover, whether diet,... more
Despite an increasing appreciation in the importance of host–microbe interactions in ecological and evolutionary processes, information on the gut microbial communities of some marine mammals is still lacking. Moreover, whether diet, environment, or host phylogeny has the greatest impact on microbial community structure is still unknown. To fill part of this knowledge gap, we exploited a natural experiment provided by an aquarium with belugas (Delphinapterus leucas) affiliated with family Monodontidae, Pacific white-sided dolphins (Lagenorhynchus obliquidens) and common bottlenose dolphin (Tursiops truncatus) affiliated with family Delphinidae, and Cape fur seals (Arctocephalus pusillus pusillus) affiliated with family Otariidae. Results show significant differences in microbial community composition of whales, dolphins, and fur seals and indicate that host phylogeny (family level) plays the most important role in shaping the microbial communities, rather than food and environment. ...
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Information on the gut microbiome composition of different mammals could provide novel insights into the evolution of mammals and succession of microbial communities in different hosts. However, there is limited information on the gut... more
Information on the gut microbiome composition of different mammals could provide novel insights into the evolution of mammals and succession of microbial communities in different hosts. However, there is limited information on the gut microbiome composition of marine mammals, especially cetaceans, because of sampling constraints. In this study, we investigated the diversity and composition of microbial communities in the stomach, midgut, and hindgut of two stranded short-finned pilot whales (Globicephala macrorhynchus) and hindgut of a stranded pygmy sperm whale (Kogia breviceps) by using 16S rRNA gene amplicon sequencing technology. On the basis of the 50 most abundant operational taxonomic units, principal coordinate analysis, and non-metric multidimensional scaling analysis, we confirmed that the gut microbial communities of the three whales were different. Our results revealed that the gut microbiome of one stranded short-finned pilot whale GM16 was dominated by Firmicutes (mainly Clostridium) and Fusobacteria; whereas that of the other pilot whale GM19 was composed of Gammaproteobacteria and Bacteroidetes (mainly Vibrio and Bacteroides, respectively), probably caused by intestinal disease and antibiotic treatment. The gut microbiome of the pygmy sperm whale was dominated by Firmicutes and Bacteroidetes. Moreover, different gastrointestinal tract regions harbored different microbial community structures. To our knowledge, this is the first report of the gut microbiome of short-finned pilot whales, and our findings will expand our current knowledge on microbial diversity and composition in the gastrointestinal tract of cetaceans. This article is protected by copyright. All rights reserved.
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Observer-based counts and photo-identification are two well-established methods with an extensive use in cetacean studies. Using these two methods, group size has been widely reported, especially for small dolphins. Both methods may come... more
Observer-based counts and photo-identification are two well-established methods with an extensive use in cetacean studies. Using these two methods, group size has been widely reported, especially for small dolphins. Both methods may come with potential errors in estimating the group size, yet there is still a lack of comparison between both methods over a broad range of group size. Particularly, biogeographical variances in group size estimates were often mixed with methodological variances, making it difficult to compare estimates from different geographic regions. Here, group size estimates of a small, shallow-water, and near-shore delphinid species, Indo-Pacific humpback dolphins (Sousa chinensis), were simultaneously sampled using observer-based counts and photo-identification at three regions in the northern South China Sea. Data showed that dolphin group size from two methods were highly variable and associated with sampling regions. Generalized linear mixed models (GLMMs) ind...
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Abstract The release of piscivorous fishes is considered crucial to alleviate eutrophication and fish miniaturization, as well as to develop sustainable fisheries management strategy for Yangtze lakes. In order to promote the stock... more
Abstract The release of piscivorous fishes is considered crucial to alleviate eutrophication and fish miniaturization, as well as to develop sustainable fisheries management strategy for Yangtze lakes. In order to promote the stock enhancement programme of a new released piscivorous fish species Culter mongolicus, growth, recapture rates, reproduction and impact of size-at-release for hatchery-reared juveniles were evaluated in three Yangtze shallow lakes during a five-year period. C. mongolicus displayed important growth capability with a body weight reaching commercial size (> 500 g) during the second released year and about 1500 g in the third year. However, a sharp decline of growth appeared quickly after several years of releasing, indicating possible issue of density-dependent growth caused by over-stocking. The recapture rates for one-month-old juveniles were less than 5%, but increased to more than 20 % when one-year-old fingerlings were selected as release size. Gonad examination and catch analysis showed that released juveniles could not succeed in building the recruitment stock due to over-fishing. Thus hatchery-reared juveniles should be released annually. Management actions that prioritize the release of fewer but larger fingerlings will improve the recapture rate and subsequent economic benefit. A new stock enhancement strategy that changes the present release-catch cycle from two years to one was proposed accordingly.
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Reproductive hormones in serum concentrations of progesterone, estradiol and testosterone in female Indo-Pacific bottlenose dolphins (Tursiops aduncus, n = 12) housed in Ocean Park Hong Kong were investigated in the present study. Results... more
Reproductive hormones in serum concentrations of progesterone, estradiol and testosterone in female Indo-Pacific bottlenose dolphins (Tursiops aduncus, n = 12) housed in Ocean Park Hong Kong were investigated in the present study. Results showed that, onset of puberty of captive Indo-Pacific bottlenose dolphins was at 5 y while sexual maturity is at six. Average serum progesterone concentrations in non-pregnant sexually mature individuals was 0.33(0.25-0.97) ng/mL (interquartile), significantly higher than in immature ones 0.26(0.25-0.38) ng/mL. This study found significant difference in serum estradiol concentrations between individuals at the onset of puberty (9.5±1.7 pg/mL, ±SD) and not (below detection limit 9 pg/mL). A slightly seasonal breeding pattern, with progesterone values tend to be higher from February to October (0.38[0.25-1.07] ng/mL) was inferred. During pregnancy, serum progesterone concentrations range from 10.54±8.74 ng/mL (indexed month post-conception [IMPC] 0) to 25.49±12.06 ng/mL (IMPC 2), and display a bimodal pattern with two peaks in early- (25.49±12.06 ng/mL, IMPC 2) and late-pregnancy (21.71±10.25 ng/mL, IMPC 12) respectively. Serum estradiol concentrations can seldom be detected in early-pregnancy and increase constantly in mid- (9.45±1.83 pg/mL) and late-pregnancy (11.88±3.81 pg/mL), with a spike (15.45±6.78 pg/mL) one month prior to delivery. Serum testosterone concentrations elevate significantly in IMPC 7 (0.36±0.10 ng/mL) compared to other months (0.16±0.10 ng/mL) of the year. The present study provides normal concentration profiles for some reproductive hormones in female Indo-Pacific bottlenose dolphins; and can contribute to the breeding monitoring of this species. Also, our study would shed further light on the reproductive physiology of small cetaceans. This article is protected by copyright. All rights reserved.
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China was home to the world’s secondhighest diversity of gibbons in the 20th century, but these species have all suffered extensive population declines, and regional species losses continue (1, 2). The Hainan gibbon (Nomascus hainanus),... more
China was home to the world’s secondhighest diversity of gibbons in the 20th century, but these species have all suffered extensive population declines, and regional species losses continue (1, 2). The Hainan gibbon (Nomascus hainanus), formerly widespread across Hainan Island (3), is now the rarest primate and among the rarest mammals (4). It represents one of the oldest gibbon lineages (5) but has received limited conservation attention compared with many other species in China. Hunting and habitat loss have reduced the species to a single high-elevation population in Bawangling National Nature Reserve (4, 6). Restricted to 15 km of fragmented rain forest within this reserve, the Hainan gibbon has persisted with fewer than 30 individuals for several decades (3, 6, 7). With China’s plan to establish a national park on Hainan, the species has a renewed chance at recovery, but challenges remain. Although the Hainan gibbon population received inconsistent financial support for protective measures in the 1980s and 1990s (6), conservation efforts since then have yielded promising signs. Two newly formed social groups were discovered in 2015 and 2019, and based on these positive trends, the total population size now likely exceeds 30 individuals (8). However, the species has extremely low genetic diversity (9), and forest degradation and conversion present barriers to the range expansion necessary Edited by Jennifer Sills for recovery (7). Increased enforcement has eliminated hunting as a threat (6, 7), but the tiny population is inherently vulnerable to stochastic events such as emerging zoonotic disease outbreaks and extreme climatic events. In 2015, the National Park system was established as China’s new protected area framework (10). Hainan Tropical Rainforest National Park will be established in 2020 (11) and will cover almost one-seventh of Hainan’s land area. The Hainan gibbon, as Hainan’s endemic primate (2), has been designated the national park’s flagship species (12). Raising the species’ profile is an important step, but crucial data gaps remain, and National Park management must be evidence-based and guided by new research. In addition to increasing funding, it is essential to improve monitoring with innovative technologies, to understand habitat structure and resource distribution, and to implement science-led forest restoration. In situ conservation remains the priority, but feasibility of intensive recovery strategies under potential emergency scenarios must be appraised (7). Assessment of future climate change impacts is also urgently needed. Effective Hainan gibbon conservation and long-term protection of China’s tropical biodiversity require robust scientific understanding, including insights from the recovery of other highly threatened species. Hui Liu*, Heidi Ma, Susan M. Cheyne, Samuel T. Turvey Wuzhishan National Long Term Forest Ecosystem Research Station, College of Forestry, Hainan University, Haikou 570228, China. Institute of Zoology, Zoological Society of London, London NW1 4RY, UK. Faculty of Social Sciences, Oxford Brookes University, Oxford OX3 0BP, UK. *Corresponding author. Email: liuhui@hainanu.edu.cn
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The present study is a retrospective analysis of 11 cases with severe acute liver failure combined with multiple organ dysfunction syndrome (MODS) performed during the period June, 2012 to December, 2014. After part of plasmapheresis with... more
The present study is a retrospective analysis of 11 cases with severe acute liver failure combined with multiple organ dysfunction syndrome (MODS) performed during the period June, 2012 to December, 2014. After part of plasmapheresis with plasma filtration adsorption combined with continuous hemodiafiltration treatment, good curative effects were obtained and the main clinical symptoms and biochemical index were significantly improved. Following treatment, 8 of the 11 patients survived at a survival rate of 72.7%, and 3 patients succumbed with a mortality of 27.3%. The results suggested that part of plasmapheresis with plasma filtration adsorption combined with continuous venovenous hemodiafiltration (CVVHDF) treatment is beneficial in the removal of metabolites and toxins. Additonally, it can effectively improve liver function and clinical symptoms, improve hepatic encephalopathy, correct the disorder of internal environment, and improve the prognosis of patients.
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ABSTRACT Counting the number of animals is essential for monitoring and management of marine mammals. Autonomous stereo acoustic event recorder (A-tag) to identify each sound source enabled to count phonating odontocetes in the wild.... more
ABSTRACT Counting the number of animals is essential for monitoring and management of marine mammals. Autonomous stereo acoustic event recorder (A-tag) to identify each sound source enabled to count phonating odontocetes in the wild. Finless porpoises were surveyed by towed A-tags in 1100 km stretch of Yangtze River from Wuhan to Shanghai. The calculated detection probability using acoustic method was approximately twice that for visual detection. The difference in detection probabilities between the two methods was caused by the large number of single individuals that were missed by visual observers. However, acoustics tended to underestimate group size due to the limited resolution of sound source bearing angles. The detection performance regarding stationary acoustic monitoring of this species was also examined. Three stereo acoustic data loggers were placed at different locations near the confluence of Poyang Lake and the Yangtze River. Acoustic monitoring confirmed the low density bottle neck of the population between the lake and the river that was consistent with visual observations. The passive pulse event monitoring was proved to be a practical and useful alternative to visual observations, especially for long-term and range-wide monitoring.
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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,... more
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-hea...
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Aquatic environments encompass the world’s most extensive habitats, rich with sounds produced by a diversity of animals. Passive acoustic monitoring (PAM) is an increasingly accessible remote sensing technology that uses hydrophones to... more
Aquatic environments encompass the world’s most extensive habitats, rich with sounds produced by a diversity of animals. Passive acoustic monitoring (PAM) is an increasingly accessible remote sensing technology that uses hydrophones to listen to the underwater world and represents an unprecedented, non-invasive method to monitor underwater environments. This information can assist in the delineation of biologically important areas via detection of sound-producing species or characterization of ecosystem type and condition, inferred from the acoustic properties of the local soundscape. At a time when worldwide biodiversity is in significant decline and underwater soundscapes are being altered as a result of anthropogenic impacts, there is a need to document, quantify, and understand biotic sound sources–potentially before they disappear. A significant step toward these goals is the development of a web-based, open-access platform that provides: (1) a reference library of known and un...
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Research Interests: Zoology, Ecology, Biogeography, Medicine, Socioecology, and 3 moreHabitat, Social Dynamics, and Group Size
We assessed habitat use by the population of Indo-Pacific humpback dolphin, Sousa chinensis, in the waters off Zhanjiang, China, by performing boat-based surveys between 2013 and 2018. In total, we gathered 253 sightings of humpback... more
We assessed habitat use by the population of Indo-Pacific humpback dolphin, Sousa chinensis, in the waters off Zhanjiang, China, by performing boat-based surveys between 2013 and 2018. In total, we gathered 253 sightings of humpback dolphins. To assess habitat use of humpback dolphins within the study area, we measured two spatial metrics at each sighting site: WDT (tide-calibrated water-depth) and DS (distance to the nearest shore). Results showed that dolphins mainly were observed in shallow (WDT: 8.46 ± 5.13 m, mean ± SD) and inshore (DS: 2.17 ± 2.14 km) waters. Their preference of inhabiting shallow waters was more apparent during the wet season (April–September) than during the dry season (October–March); however, they were encountered in waters much closer to shore during the dry season than the wet season. By weighting survey effort, our sighting density maps further confirmed that humpback dolphins changed their habitat use between wet and dry seasons. Such spatiotemporal va...
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Indo-Pacific humpback dolphins (Sousa chinensis) inhabit shallow coastal waters of the Indo-Pacific region including southeast China, with at least six putative populations identified to date in Chinese waters. However, the connectivity... more
Indo-Pacific humpback dolphins (Sousa chinensis) inhabit shallow coastal waters of the Indo-Pacific region including southeast China, with at least six putative populations identified to date in Chinese waters. However, the connectivity among these populations has not yet been investigated. In the present study, we compared and cross-matched photographic catalogs of individual dolphins collected to date in the Pearl River Delta region, Leizhou Bay, Sanniang Bay, and waters southwest of Hainan Island, a total of 3158 individuals, and found no re-sighting of individual dolphins among the four study areas. Furthermore, there was a notable difference in the pigmentation pattern displayed by individuals from these four regions. We suggest that this may be a phenotypical expression of fine-scale regional differentiation among humpback dolphin groups, possibly distinct populations. Given the considerable conservation management implications it may carry (e.g. definition of management units), further research is much needed. This article is protected by copyright. All rights reserved.
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Group size is a key social trait influencing population dynamics of group-living animals. The Indo-Pacific humpback dolphins (IPHDs), Sousa chinensis, a shallow water delphinid species, display a fission-fusion social system. Yet little... more
Group size is a key social trait influencing population dynamics of group-living animals. The Indo-Pacific humpback dolphins (IPHDs), Sousa chinensis, a shallow water delphinid species, display a fission-fusion social system. Yet little is known about how social organization of this species vary with temporal scales and behavioral state. In this study, we sampled group size estimates from the world’s second largest population of humpback dolphins (Sousa spp.), which inhabit the eastern waters of Zhanjiang, China. IPHD group sizes changed seasonally and inter-annually, but not with tidal phases. Group sizes also changed with behavioral state of IPHD groups and with number of mother-calf pairs present. IPHDs formed larger groups in the autumn than in other seasons, which might be related to seasonal changes in food availability and reproductive cycle. Of the groups observed, we recorded the presence of mother-calf pair in 85 groups (i.e., nursery groups: 47 ones with one pair, 25 ones...
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Significance Divergent lineages can respond to common environmental factors through convergent processes involving shared genomic components or pathways, but the molecular mechanisms are poorly understood. Here, we provide genomic... more
Significance Divergent lineages can respond to common environmental factors through convergent processes involving shared genomic components or pathways, but the molecular mechanisms are poorly understood. Here, we provide genomic resources and insights into the evolution of mammalian lineages adapting to aquatic life. Our data suggest convergent evolution, for example, in association with thermoregulation through genes associated with a surface heat barrier ( NFIA ) and internal heat exchange ( SEMA3E ). Combined with the support of previous reports showing that the UCP1 locus has been lost in many marine mammals independently, our results suggest that the thermostatic strategy of marine mammals shifted from enhancing heat production to limiting heat loss.
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SUMMARYRuns of homozygosity (ROH) occur when offspring receive the same ancestral haplotype from both parents, and, accordingly, reduce individual heterozygosity. Their distribution throughout the genome contains information on the... more
SUMMARYRuns of homozygosity (ROH) occur when offspring receive the same ancestral haplotype from both parents, and, accordingly, reduce individual heterozygosity. Their distribution throughout the genome contains information on the probability of inbreeding mediated by mating system and population demography. Here, we investigate variation in killer whale demographic history as reflected in genome-wide heterozygosity, using a global dataset of 26 genomes. We find an overall pattern of lower heterozygosity in genomes sampled at high latitudes, with hundreds of short ROH (< 1Mbp) reflecting high background relatedness due to coalescence of haplotypes during bottlenecks associated with founder events during post-glacial range expansions. Across most of the species’ range, intermediate length ROH (1-10Mb) revealed long-term inbreeding in 22 of the 26 sampled killer whale genomes, consistent with the high social philopatry observed in all populations studied to date. Inbreeding coeffi...
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Based on optimal foraging theory, animals are expected to maximize foraging benefits whilst minimizing risks. Despite risking being subjected to anthropogenic impacts such as water contamination, marine traffic, and underwater noise,... more
Based on optimal foraging theory, animals are expected to maximize foraging benefits whilst minimizing risks. Despite risking being subjected to anthropogenic impacts such as water contamination, marine traffic, and underwater noise, estuaries have been identified as the preferred habitat of the Indo‐Pacific humpback dolphin (Sousa chinensis, IPHD). However, it remains unclear why this vulnerable species favours such risky habitats. Here, an exploratory case study in Zhanjiang estuary, China, was conducted to test the hypothesis that IPHDs select estuarine habitats as a trade‐off that maximizes foraging opportunities whilst minimizing the risk of mortality. The results showed that IPHDs accept greater mortality risks for higher food rewards but select habitats with lower risks when food rewards are similar between two locations. Although this type of information is important for underpinning models for individual dolphins, its principal role is to show environmental protection agencies why IPHDs favour estuaries despite the increased mortality risks. Habitat conservation plans should carefully consider prey stocks, possibly through the presence of marine protected areas near estuaries, as local overfishing may lead vulnerable cetacean populations to take greater risks.
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Marine mammals, whose ancestors once roamed the land, have intrigued scientists for centuries. Although they share many similar morphological characteristics, the innovations for mammalian aquatic life were independently acquired at least... more
Marine mammals, whose ancestors once roamed the land, have intrigued scientists for centuries. Although they share many similar morphological characteristics, the innovations for mammalian aquatic life were independently acquired at least seven times. Extant marine mammals are found in three orders: Artiodactyla, Sirenia, and Carnivora. To better understand the evolution of marine mammals, we generated the genomes of 17 marine mammals (11 cetaceans and six pinnipeds). Comparing these with publicly available marine mammal and terrestrial taxon genomes provides new insights into the evolutionary history of these iconic species. Focusing on the oldest groups of living marine mammals, the cetaceans, pinnipeds, and sirenians, we uncover genomic variations in marine mammals, including brown fat cell differentiation regulatory gene, NFIA, and forelimb development related genes, Xylt1 and Fam20b, which could underlie marine adaptations across these diverse taxonomic lineages.
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Shipping noise is a widespread and relatively loud sound source among human-induced underwater sounds. The impacts of shipping noise are of special concern for Indo-Pacific humpback dolphins (Sousa chinensis), as they inhabit shallow and... more
Shipping noise is a widespread and relatively loud sound source among human-induced underwater sounds. The impacts of shipping noise are of special concern for Indo-Pacific humpback dolphins (Sousa chinensis), as they inhabit shallow and nearshore habitats and are highly dependent on sound for survival. This study synthesizes our current understanding of the potential impacts of shipping noise on Indo-Pacific humpback dolphins combined with knowledge on sound production and hearing of these animals and the impacts of noise on other whales and dolphins. For further protection and management of Indo-Pacific humpback dolphins and their habitats, shipping noise should be regulated and mitigated to modify sound from ships, to reduce overall noise levels, and to set more marine protected areas (MPAs) covering most Indo-Pacific humpback dolphin habitats with seasonal and geographical restrictions to avoid ensonification of shipping noise. The emphasis for future research should be on obtai...
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In this paper, the authors address the design of optimal waveform for target detection and parameter estimation based on the features analysis of the whistle of Indo-pacific humpback dolphins. A set of types of waveforms exist in the... more
In this paper, the authors address the design of optimal waveform for target detection and parameter estimation based on the features analysis of the whistle of Indo-pacific humpback dolphins. A set of types of waveforms exist in the sequence of whistle calls. Considering the perfect performance of non-linear frequency modulated and multi-harmonics structure in anti-range sidelobe and anti-reverberation, several fusion schemes of several kinds of waveforms are explored and fusion results are studied analytically and from simulation. It is concluded that the bionic harmonic fused signal shows good time resolution, and improve the performance of suppressing reverberation. Research result provides nice reference and application value in underwater sonar based on bionic acoustic signal.
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While the transmission beam of odontocetes has been described in a number of studies, the majority of them that have measured the transmission beam in two dimensions were focused on captive animals. Within the current study, a dedicated... more
While the transmission beam of odontocetes has been described in a number of studies, the majority of them that have measured the transmission beam in two dimensions were focused on captive animals. Within the current study, a dedicated cross hydrophone array with nine elements was used to investigate the echolocation transmission beam of free-ranging Indo-Pacific humpback dolphins. A total of 265 on-axis clicks were analyzed, from which the apparent peak to peak source levels ranged between 168 to 207 dB (mean 184.5 dB ± 6.6 dB). The 3-dB beam width along the horizontal and vertical plane was 9.6° and 7.4°, respectively. Measured separately, the directivity index of the horizontal and vertical plane was 12.6 and 13.5 dB, respectively, and the overall directivity index (both planes combined) was 29.5 dB. The beam shape was slightly asymmetrical along the horizontal and vertical axis. Compared to other species, the characteristics of the transmitting beam of Indo-Pacific humpback dol...
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Computed tomography (CT) imaging and sound experimental measurements were used to reconstruct the acoustic properties (density, velocity, and impedance) of the forehead tissues of a deceased pygmy sperm whale (Kogia breviceps). The... more
Computed tomography (CT) imaging and sound experimental measurements were used to reconstruct the acoustic properties (density, velocity, and impedance) of the forehead tissues of a deceased pygmy sperm whale (Kogia breviceps). The forehead was segmented along the body axis and sectioned into cross section slices, which were further cut into sample pieces for measurements. Hounsfield units (HUs) of the corresponding measured pieces were obtained from CT scans, and regression analyses were conducted to investigate the linear relationships between the tissues' HUs and velocity, and HUs and density. The distributions of the acoustic properties of the head at axial, coronal, and sagittal cross sections were reconstructed, revealing that the nasal passage system was asymmetric and the cornucopia-shaped spermaceti organ was in the right nasal passage, surrounded by tissues and airsacs. A distinct dense theca was discovered in the posterior-dorsal area of the melon, which was character...
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While the low-frequency communication sounds of Indo-Pacific humpback dolphins (Sousa chinensis) have been reported in a number of papers, the high-frequency echolocation signals of Sousa chinensis, especially those living in the wild,... more
While the low-frequency communication sounds of Indo-Pacific humpback dolphins (Sousa chinensis) have been reported in a number of papers, the high-frequency echolocation signals of Sousa chinensis, especially those living in the wild, have been less studied. In the current study, echolocation signals of humpback dolphins were recorded in Sanniang Bay, Guangxi Province, China, using a cross-type hydrophone array with five elements. In total, 77 candidate on-axis clicks from 77 scans were selected for analysis. The results showed that the varied peak-to-peak source levels ranged from 177.1 to 207.3 dB, with an average of 187.7 dB re: 1 μPa. The mean peak frequency was 109.0 kHz with a -3-dB bandwidth of 50.3 kHz and 95% energy duration of 22 μs. The -3-dB bandwidth was much broader than the root mean square bandwidth and exhibited a bimodal distribution. The center frequency exhibited a positive relationship with the peak-to-peak source level. The clicks of the wild Indo-Pacific hump...
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The clicks of Yangtze finless porpoises (Neophocaena asiaeorientalis asiaeorientalis) from 7 individuals in the tank of Baiji aquarium, 2 individuals in a netted pen at Shishou Tian-e-zhou Reserve and 4 free-ranging individuals at... more
The clicks of Yangtze finless porpoises (Neophocaena asiaeorientalis asiaeorientalis) from 7 individuals in the tank of Baiji aquarium, 2 individuals in a netted pen at Shishou Tian-e-zhou Reserve and 4 free-ranging individuals at Tianxingzhou were recorded using a broadband digital recording system with four element hydrophones. The peak-to-peak apparent source level (ASL_pp) of clicks from individuals at the Baiji aquarium was 167 dB re 1 μPa with mean center frequency of 133 kHz, -3dB bandwidth of 18 kHz and -10 dB duration of 58 μs. The ASL_pp of clicks from individuals at the Shishou Tian-e-zhou Reserve was 180 dB re 1 μPa with mean center frequency of 128 kHz, -3dB bandwidth of 20 kHz and -10 dB duration of 39 μs. The ASL_pp of clicks from individuals at Tianxingzhou was 176 dB re 1 μPa with mean center frequency of 129 kHz, -3dB bandwidth of 15 kHz and -10 dB duration of 48 μs. Differences between the source parameters of clicks among the three groups of finless porpoises sug...
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Research Interests:
Our study intended to prove whether agonistic autoantibodies to angiotensin II type 1 receptor (AT1-AAs) exist in patients with coronary heart disease (CHD) and affect the human endothelial cell (HEC) by upregulating proinflammatory... more
Our study intended to prove whether agonistic autoantibodies to angiotensin II type 1 receptor (AT1-AAs) exist in patients with coronary heart disease (CHD) and affect the human endothelial cell (HEC) by upregulating proinflammatory cytokines expression involved in NF-κB pathway. Antibodies were determined by chronotropic responses of cultured neonatal rat cardiomyocytes coupled with receptor-specific antagonists (valsartan and AT1-EC2) as described previously. Interleukin-6 (IL-6), vascular cell adhesion molecule-1 (VCAM-1), and monocyte chemotactic protein-1 (MCP-1) expression were improved at both mRNA and protein levels in HEC, while NF-κB in the DNA level was improved detected by electrophoretic mobility shift assays (EMSA). These improvements could be inhibited by specific AT1 receptor blocker valsartan, NF-κB blocker pyrrolidine dithiocarbamate (PDTC), and specific short peptides from the second extracellular loop of AT1 receptor. These results suggested that AT1-AAs, via the...