Neophocaena Phocaenoides Asiaeorientalis Research Articles

Analysis of the population density trend of the finless porpoise based on smart IoT technologies

AbstractWith the rapid expansion of human activities, natural environmental systems are under severe threat. Yangtze River, the largest river in China, contains abundant biological resources. However, the ecosystem of the Yangtze River has been threatened by the rapid rise of human activities due to economic development in the 1990s. The Yangtze finless porpoise Neophocaena phocaenoides asiaeorientalis is a critically endangered flagship species in the Yangtze River. Although scientists have conducted surveys studying the abundance of Yangtze finless porpoise, the length of the investigation period of these studies was restricted. Here, we reported our meta-analysis results by collecting data on the abundance of the Yangtze finless porpoise population from published papers over 33 years. We found that the pooled effect size using the random effect model across all these studies was – 0.36 (95% confident interval (CI) – 0.48,– 0.24, P < 0.05), indicating that the porpoise population has undergone a declining pattern after the year 2003. The operation of the Three Gorges Dam was one important but not the only factor resulting in the decline of the porpoise population. More actions should be taken for porpoise and habitat protection and more studies should be done to assess the impact of dams on the porpoise population in Poyang Lake. Only in this way can marine life be better protected, and the marine environment can better achieve sustainable development.

Sound Reception in the Yangtze Finless Porpoise and Its Extension to a Biomimetic Receptor.

Sound reception was investigated in the Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) at its most sensitive frequency. The computed tomography scanning, sound speed, and density results were used to develop a three-dimensional numerical model of the porpoise sound-reception system. The acoustic fields showed that sounds can reach the ear complexes from various pathways, with distinct receptivity peaks on the forward, left, and right sides. Reception peaks were identified on the ipsilateral sides of the respective ears and found on the opposite side of the ear complexes. These opposite maxima corresponded to subsidiary hearing pathways in the whole head, especially the lower head, suggesting the complexity of the sound-reception mechanism in the porpoise. The main and subsidiary sound-reception pathways likely render the whole head a spatial receptor. The low-speed and -density mandibular fats, compared to other acoustic structures, are significant energy enhancers for strengthening forward sound reception. Based on the porpoise reception model, a biomimetic receptor was developed to achieve directional reception, and in parallel to the mandibular fats, the silicon material of low speed and density can significantly improve forward reception. This bioinspired and biomimetic model can bridge the gap between animal sonar and artificial sound control systems, which presents potential to be exploited in manmade sonar.

A metagenomic insight into the Yangtze finless porpoise virome.

The Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) inhabiting the Yantze River, China is critically endangered because of the influences of infectious disease, human activity, and water contamination. Viral diseases are one of the crucial factors that threatening the health of Yangtze finless porpoise. However, there are few studies which elaborate the viral diversity of Yangtze finless. Therefore, this study was performed to investigate the viral diversity of Yangtze finless by metagenomics. Results indicated that a total of 12,686,252 high-quality valid sequences were acquired and 2,172 virus reads were recognized. Additionally, we also obtained a total of 10,600 contigs. Phages was the most abundant virus in the samples and the ratio of DNA and RNA viruses were 69.75 and 30.25%, respectively. Arenaviridae, Ackermannviridae and Siphoviridae were the three most predominant families in all the samples. Moreover, the majority of viral genus were Mammarenavirus, Limestonevirus and Lambdavirus. The results of gene prediction indicated that these viruses play vital roles in biological process, cellular component, molecular function, and disease. To the best of our knowledge, this is the first report on the viral diversity of Yangtze finless porpoise, which filled the gaps in its viral information. Meanwhile, this study can also provide a theoretical basis for the establishment of the prevention and protection system for virus disease of Yangtze finless porpoise.

A ~ 40-year paleoenvironmental record from the Swan Oxbow, Yangtze River, China, inferred from testate amoebae and sedimentary pigments

We present a ~ 40–year record of environmental change in the Swan Oxbow, Yangtze River, China, inferred from testate amoeba and sedimentary pigment data, combined with remote sensing and analysis of local socio–economic growth. These data indicate there were several distinct phases of aquatic conditions linked to human activities in the region: (1) Between ca. AD 1970 and 1984, there may have been some exchange of water and organic matter between the Swan Oxbow and the main river channel, following initial hydrologic disconnection in 1972. The lake area was relatively large in the early phase after the oxbow first formed, and the trophic state generally increased during that time frame, (2) From ca. AD 1984 to 1992, the lake area was about a third smaller in size, while the human population and GDP increased about 10% and 10x, respectively, compared to values in 1975. The nutrient status (inferred from testate amoeba and pigment data) increased, owing to the greater discharge of nutrients and separation of the Swan Oxbow from the main Yangtze River, which reduced water supply and increased sedimentation in the oxbow, (3) From ca. AD 1992 to 2003, the lake continued to diminish in size, to an area < 20 km2, except in 1998, when a major flood occurred. The testate amoeba and pigment data suggest that water quality had improved by that time, which probably reflects efforts to control agricultural and industrial activities, including establishment of two national reserves in 1992 and 1993, created to protect the rare Pere David’s deer (Elaphurus davidianus) and the freshwater Baiji dolphin (Neophocaena phocaenoides asiaeorientalis), (4) From ca. AD 2003 to 2005, the water area remained relatively unchanged, owing to construction of a dam following the 1998 flood. Occurrence of testate amoeba species Difflugia biwae and D. tuberspinifera, however, indicates that water pollution and eutrophication had been controlled in Swan Oxbow. The Swan Oxbow yielded important information about the effects of environmental protection and restoration in the middle reaches of the Yangtze River.

A review on bio-sonar behaviour research of Yangtze finless porpoise using animal bone acoustic data loggers

In recent 10 years, a miniature stereo acoustic data logger (A-tag, W20-AS, Little Leonardo, Japan) has been used to observe the bio-sonar behaviour of free-ranging Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis). The A-tag is small enough to be attached on the one of the smallest odontocetes by using suction cups. The A-tag with two external hydrophones can record the sonar pulse intensity, inter-click-intervals, and sound source direction measured by time arrival difference of sounds at the two hydrophones. Major outcomes by A-tag were the in situ off-axis sonar beam pattern, attention and approach phase of biosonar behaviour, scanning sonar of rolling animals, and social contacts among free-ranging Yangtze finless porpoises. In addition, frequent ultrasonic sound production was confirmed that seemed to be a reason of high detection performance of this species using passive acoustic monitoring of finless porpoises. This biosonar monitoring method using miniature data logger system de...

Analysis of the bacterial diversity in the fecal material of the endangered Yangtze finless porpoise, Neophocaena phocaenoides asiaeorientalis

The aim of this study was to determine the bacteria present in the fecal material of the endangered Yangtze finless porpoise, Neophocaena phocaenoides asiaeorientalis. Fecal samples were collected from 12 Yangtze finless porpoises living in the wild at Poyang Lake, located in Jiangxi Province, China. To determine the bacterial diversity, a 16S rRNA gene clone library using the bacterial PCR primers fD1 and rP2, was prepared. A total of 138 near-full-length sequences were analyzed and 39 operational taxonomic units (OTUs) were identified. Sequences showing ≥97% similarity were grouped together as an OTU. Six different phyla were identified in which 38 OTUs were classified. Most of the OTUs contained sequences belonged to the phylum Firmicutes (51.3%), followed by Tenericutes (17.9%), Proteobacteria (15.4%), Actinobacteria (7.7%), Deinococcus-Thermus (2.6%) and Cyanobacteria (2.6%). A phylum could not be assigned for one clone within one OTU (2.6%). It appears that the Yangtze finless porpoise has a more diverse range of bacteria compared to other aquatic mammals, such as seals.

Chromosomal rearrangements and karyotype evolution in carnivores revealed by chromosome painting.

Chromosomal evolution in carnivores has been revisited extensively using cross-species chromosome painting. Painting probes derived from flow-sorted chromosomes of the domestic dog, which has one of the most rearranged karyotypes in mammals and the highest dipoid number (2n=78) in carnivores, are a powerful tool in detecting both evolutionary intra- and inter-chromosomal rearrangements. However, only a few comparative maps have been established between dog and other non-Canidae species. Here, we extended cross-species painting with dog probes to seven more species representing six carnivore families: Eurasian lynx (Lynx lynx), the stone marten (Martes foina), the small Indian civet (Viverricula indica), the Asian palm civet (Paradoxurus hermaphrodites), Javan mongoose (Hepestes javanicas), the raccoon (Procyon lotor) and the giant panda (Ailuropoda melanoleuca). The numbers and positions of intra-chromosomal rearrangements were found to differ among these carnivore species. A comparative map between human and stone marten, and a map among the Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis), stone marten and human were also established to facilitate outgroup comparison and to integrate comparative maps between stone marten and other carnivores with such maps between human and other species. These comparative maps give further insight into genome evolution and karyotype phylogenetic relationships among carnivores, and will facilitate the transfer of gene mapping data from human, domestic dog and cat to other species.

Establishment and characterization of fibroblast cell lines from the skin of the Yangtze finless porpoise

The Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis), as the sole freshwater subspecies of N. phocaenoides, is endemic to the Yangtze River and its adjacent lakes. Its population has declined significantly over recent decades. In this study, we established a skin-derived finite fibroblast cell line of the Yangtze finless porpoise, named YFP-SF1, using primary cell culture methods, and an immortalized cell line, T-YFP-SF1, through co-transfection (GFP and SV40 T antigens) techniques. YFP-SF1 proliferated continuously with a minimum population doubling time of 31h and exhibited age-dependent changes in growth rate. T-YFP-SF1 cells exhibited fibroblast morphology and were characterized by a shorter doubling time, higher attachment efficiencies, colony formation at a low seeding density, and growth in low serum concentrations. Anchorage independence and foci formation in the cell monolayer were observed from passage 36. The chromosome number of YFP-SF1 and T-YFP-SF1 remained stable at 2n = 44 in the early passages, and the viability of thawed cells remained above 90% after cryopreservation in liquid nitrogen. Taken together, we have established fibroblast cell lines of Yangtze finless porpoise for the first time, which might assist as an in vitro model for this endangered mammal.

Auditory temporal resolution and evoked responses to pulsed sounds for the Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis)

Temporal cues are important for some forms of auditory processing, such as echolocation. Among odontocetes (toothed whales, dolphins, and porpoises), it has been suggested that porpoises may have temporal processing abilities which differ from other odontocetes because of their relatively narrow auditory filters and longer duration echolocation signals. This study examined auditory temporal resolution in two Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis) using auditory evoked potentials (AEPs) to measure: (a) rate following responses and modulation rate transfer function for 100kHz centered pulse sounds and (b) hearing thresholds and response amplitudes generated by individual pulses of different durations. The animals followed pulses well at modulation rates up to 1,250Hz, after which response amplitudes declined until extinguished beyond 2,500Hz. The subjects had significantly better hearing thresholds for longer, narrower-band pulses similar to porpoise echolocation signals compared to brief, broadband sounds resembling dolphin clicks. Results indicate that the Yangtze finless porpoise follows individual acoustic signals at rates similar to other odontocetes tested. Relatively good sensitivity for longer duration, narrow-band signals suggests that finless porpoise hearing is well suited to detect their unique echolocation signals.

Detection of Helicobacter in the fecal material of the endangered Yangtze finless porpoise Neophocaena phocaenoides asiaeorientalis

In animals, infection by the Epsilonproteobacteria Helicobacter spp. and H. cetorum is widespread. It has been suggested that H. cetorum may cause gastritis in cetaceans. The aim of our study was to investigate the presence of Helicobacter spp. in the fecal material of the endangered Yangtze finless porpoise Neophocaena phocaenoides asiaeorientalis. The fecal material of 12 porpoises living in the wild in Poyang Lake and 1 porpoise living in captivity at the Wuhan Baiji Dolphinarium were examined by PCR for the presence of Helicobacter spp. The fecal material of 8 of 12 wild porpoises and the captive porpoise were positive for Helicobacter spp. as determined by PCR using Helicobacter-specific primers, which target the 16S rRNA gene. A 16S rRNA clone library was then prepared from 1 sample isolated from a female porpoise living in the wild. DNA sequence analysis from 3 of the clones showed 98 to 99% identity to the H. cetorum 16S rRNA gene. These results demonstrate the prevalence of Helicobacter spp. and H. cetorum in endangered freshwater finless porpoises.

Hearing pathways in the finless porpoise, Neophocaena phocaenoides, and implications for noise impacts.

How an animal receives sound will influence how it uses or is impacted by sound. While the “jaw hearing” hypothesis is well supported, work has been limited to a few “representative” species. There are clear variations in the jaw and head morphologies of odontocete species suggesting subtle variation in sound reception. Here we address how a divergent cetacean species, the Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis), receives sound. Noise impacts on this subspecies are a concern as they inhabit waters with many acoustic sources. Hearing was measured using auditory evoked potentials. Click and amplitude modulated tone stimuli were presented at nine locations on the head and body using a jawphone transducer. Thresholds were compared to anatomical dissections and CT scans of porpoise heads. Minimum thresholds and best hearing locations were at the cheek‐fat‐pad and distal to the porpoise bulla. However, thresholds were not substantially different at locations from the rostrum tip to the ear (11.6 dB). This minimal variation is quite different from the 30–40 dB differences found across the head of bottlenose dolphins and belugas suggesting differences in how divergent odontocetes receive sound. Porpoises may have relatively less “shading” of sounds and are potentially more susceptible to masking effects.

Variations in independent areas of activity of captive Yangtze finless porpoises, Neophocaena phocaenoides asiaeorientalis, during the acclimation period after wild capture

The acclimation process of Yangtze finless porpoises to a limited holding pool after their introduction to this new captive environment is presented. One male (#1) and two female (#2, #3) finless porpoises, newly captured from two different sections of China's Yangtze River, were observed in an indoor holding pool with an area of 155 m(2) from January 1997 to January 1998 (animal #3 was removed from the pool in mid-February 1997). Three separate areas in the pool were predefined. Time spent in each of the areas was individually monitored two or three sessions a week using the focal sampling method. In total, 71.3 h of observations (316 sessions) were recorded, with an average observation time each month of about 2.4 h (10 sessions) for each porpoise. The percentage of time spent in each area per month was calculated for each porpoise, and the variations in the percentage of time spent in each area was compared. Results indicated that independent areas of activity existed among porpoises during the early stages of captivity. However, over time, the frequent approaches of the female to the male caused these areas to fade away, resulting in almost equal use of the entire pool area by the newly formed group. The existence of the independent areas of activity during the early months of captivity indicates that newly introduced individuals from different wild subgroups may need separate areas for activities. However, further studies with more animals are needed to draw more general conclusions about the individual areas of activity of this subspecies when in captivity.

Ethogram of Yangtze finless porpoise calves (Neophocaena phocaenoides asiaeorientalis).

Underwater behavioral patterns of one Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) calf in captivity and those performed on the water surface by two calves in semi-natural environment were focally followed and continuously recorded until one year postpartum to construct the ethogram. The results indicate that 1) the three calves could display diverse and active behavioral patterns; 2) soon after birth, patterns critical for survival appeared first; 3) playful and social patterns predominated the ethogram; 4) most of the patterns were alike across age classes; 5) most of the patterns appeared at the calves' early life stage. It is possible that the above characteristics are adaptively shaped by the aquatic and social life of this subspecies.

Widespread passive acoustic detection of Yangtze finless porpoise using miniature stereo acoustic data-loggers: A review

Data on distribution, abundance, ecology, and behavior are essential for conservation and management of endangered animals in the wild. Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) is an endangered small odontocete species, living exclusively in the Yangtze River and its connecting Poyang and Dongting Lakes. Frequent production of high-frequency bio-sonar signals allows the animal to be detectable using passive acoustic methods. Recently, a stereo acoustic event data-logger (A-tag) has been used extensively to detect the animal by using both fixed and mobile platforms. The passive acoustic monitoring methods were not only successful in detecting the presence of animals, but also in counting, localizing, and tracking phonating individuals. Underwater behavior observed acoustically helped to assess possible effects of vessels on the animals during acoustic surveys.

Variation in sexual behaviors in a group of captive male Yangtze finless porpoises ( Neophocaena phocaenoides asiaeorientalis): motivated by physiological changes?

Most male mammals in temperate regions demonstrate seasonal sexual behaviors that coincide with seasonal variations in gonadal activities and androgen hormones. The Yangtze finless porpoise is a temperate freshwater cetacean species and an obvious seasonal breeder. To investigate the relationship between sexual behavior and gonadal activity in this animal, testicular size (volume) and structure (ultrasonogram pixel intensity) of two adult male porpoises (AF, AB) and one sub-adult male (TT) were longitudinally monitored from November 2008 to November 2009. Serum testosterone concentration was also monitored during the same period. Variations in the frequency of sexual behavior in AF and AB had similar, but seasonal trends. Their testicular size and pixel intensity also varied seasonally. Testicular size increased in March, peaked from April through June, and decreased gradually from August through September, whereas testicular pixel intensity started to increase in early February. The frequency of sexual behavior was positively correlated with testicular volume and pixel intensity (P = 0.000018 and P = 0.00012, respectively) in AF. Serum testosterone concentrations also varied. The sub-adult male porpoise, TT, was undergoing puberty, as evidenced by its marked increase in testicular volume, testicular pixel intensity, and serum testosterone concentrations from the beginning of 2009. Interestingly, TT exhibited the highest frequency of sexual behavior, most of which was same-sex pairing. However, its oversexed behavior neither quantitatively correlated with its smaller testicular volume (P = 0.61) nor with its testicular pixel intensity (P = 0.69).

Some observations on the sociosexual behavior of a captive male Yangtze finless porpoise calf (Neophocaena phocaenoides asiaeorientalis)

Sociosexual behavior in a captive male Yangtze finless porpoise calf (Neophocaena phocaenoides asiaeorientalis) was studied during its first year postpartum. This behavior was first observed at 1 month postpartum. During the year, (1) each event of the sociosexual behavior typically lasted 6–9 s and the frequency was 2.8 occurrences h−1; (2) ventral–ventral was the predominant sociosexual gesture; (3) prior to sociosexual interactions, the calf generally bonded with the receiver; (4) the mother was his preferred sociosexual partner but other adults of both sexes were also involved; (5) the frequency of sociosexual behavior decreased until the 9th month postpartum and increased thereafter.

B-Mode ultrasonographic evaluation of the testis in relation to serum testosterone concentration in male Yangtze finless porpoise ( Neophocaena phocaenoides asiaeorientalis) during the breeding season

The use of ultrasonography as a noninvasive tool for assessing the reproductive status of the male Yangtze finless porpoise (YFP; Neophocaena phocaenoides asiaeorientalis) was validated by correlating ultrasonographically determined testicular volume (TV) and testicular parenchyma pixel intensity (PI) with serum testosterone (T) concentration. The testes of 13 free-ranging male YFPs from the Tian-e-Zhou Reserve and three captive animals from the Baiji Dolphinarium (Wuhan, China) were examined ultrasonographically during April 2008. Testis volume was determined using Lambert's formula for an ellipsoid. Testicular parenchyma PI was evaluated by analyzing testicular ultrasonograms using pixel analysis software (Image J). Serum T concentrations were determined using a single-antibody radioimmunoassay. The TV, PI, and serum T concentration were low and similar in animals with body length <133 cm, highest in those with body length ≥142 cm, and highly variable in those with body length from 133 to 141 cm. Both TV and PI were closely correlated with serum T concentration (r = 0.91 and r = 0.85, respectively; P < 0.01), indicating a consistent association between structural and functional development of the testis. In conclusion, we inferred that puberty onset in male YFPs occurred when TV was >150 cm 3 and PI was >60 during the breeding season and that testicular ultrasonography and pixel analysis was an efficient, noninvasive, real-time tool to evaluate testicular function of live male YFPs.

Population status, threats and conservation of the Yangtze finless porpoise

The Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) is currently limited to the middle and lower reaches of the Yangtze River from Yichang to Shanghai, China, and the adjoining Poyang and Dongting Lakes. Its population size has decreased remarkably during the last several decades due to the heavy impact of human activities, including overfishing of prey species, water development projects that cause attendant habitat loss and degradation, water pollution, and accidental deaths caused by harmful fishing gear and collisions with motorized vessels. It was estimated that the number of remaining individuals was down to approximately 1800 in 2006, a number that is decreasing at a rate as high as 5% per year. Three conservation measures - in situ and ex situ conservation and captive breeding have been applied to the protection of this unique porpoise since the early 1990s. Seven natural and two “semi-natural” reserves have so far been established. Since 1996, a small group of finless porpoises has been successfully reared in a facility at the Institute of Hydrobiology of the Chinese Academy of Sciences; three babies were born in captivity on July 5, 2005, June 2, 2007 and July 5, 2008. These are the first freshwater cetaceans ever born in captivity in the world. Several groups of these porpoises caught in the main stream of the Yangtze River, or rescued, have been introduced into the Tian’e-Zhou Semi-natural Reserve since 1990. These efforts have proven that, not only can these animals survive in the area, they are also to reproduce naturally and successfully. More than 30 calves had been born in the reserve since then, with one to three born each year. Taking deaths and transfers into account, there were approximately 30 individuals living in the reserve as of the end of 2007. Among eight mature females captured in April 2008, five were confirmed pregnant. This effort represents the first successful attempt at off-site protection of a cetacean species in the world, and establishes a solid base for conservation of the Yangtze finless porpoise. A lesson must be drawn from the tragedy of Chinese River Dolphin (Lipotes vexillifer), which has already been declared likely extinct. Strong, effective and appropriate protective measures must be carried out quickly to prevent the Yangtze finless porpoise from becoming a second Chinese River Dolphin, and save the biodiversity of the Yangtze River as a whole.

Physiological responses to capture and handling of free-ranging male Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis)

We captured free-ranging male Yangtze finless porpoises over three seasons and assayed leukocytes and serum biochemistry to investigate physiological responses to the capture and handlings. Serum thyroid hormones (THs) declined sharply in those porpoises compared with hormone variation in a captive male finless porpoise. Hypernatremia and hypokalemia were also significant in the free-ranging animals suggesting that conservation of serum sodium might be acutely vital for this freshwater subspecies. The animals captured in spring showed more significant neutrophilia and eosinopenia than those captured in autumn suggesting that they may be more affected by capture during the breeding season. Furthermore, physical examination of porpoises when out of the water was apparently stressful, particularly when they were kept out of the water for longer periods. However, an increase in circulating THs may be an adaptive response to accommodate these short-term stresses.

Ultrastructure of the Spermatozoa of the Yangtze Finless Porpoise (Neophocaena phocaenoides asiaeorientalis)

Semen sample was collected from two captive adult Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis) during physical examination. One individual was aged about 9 years with body length 143 cm (total length) and body weight 46.1 kg in 2003. The age of the other was unknown and its body length was 147 cm and body weight was 43 kg in 2004. Ultrastructure of their spermatozoa was examined using scanning and transmission electron microscope. The sperm concentration was 4.17 x 10(9) spermatozoa per ml by the cytometer. The approximate dimensions of the spermatozoa were as follows: head length, 3.366 +/- 0.140 microm (mean +/- SE, n = 15); head width, 1.896 +/- 0.099 microm (n = 15); and neck length, 1.004 +/- 0.074 microm (n = 10). The tail included midpiece, principal piece and terminal piece. The length of the midpiece was 1.882 +/- 0.077 microm (n = 9). There is no apparent boundary between the principal piece and the terminal piece, so the length of the principal piece and the terminal piece was 44.612 +/- 3.485 microm (n = 5). Total length of the spermatozoa was 53.314 +/- 4.580 microm (n = 10). The acrosome covered approximately 45.8% of the anterior portion of the head.