Anthropogenic footprints are invading global habitats of Indo-Pacific humpback dolphins

As ecologically fragile areas,coastal zones are affected by both anthropogenic activities and climate change.However,the impacts of these factors on large nearshore mammals,such as Indo-Pacific humpback dolphins(IPHDs,Sousa chinensis),are poorly understood.Here,modeling revealed that the suitable habitats of IPHDs are affected mainly by the sea surface temperature(SST),and the habitat suitability decreases as the distance to the nearest coastline increases.In addition,anthropogenic activities involving demersal fishing,contamination and shipping have narrowed IPHD habitats and reduced the habitat suitability.We found that climate change will further narrow suitable habitats located farther than 7 km from coastlines and trigger habitat losses in the eastern Taiwan Strait by 2090-2100 under the Representative Concentration Pathway(RCP)8.5 scenario.The projected decreases in habitat suitability and area emphasize the urgency of establishing connected marine protected areas(MPAs)while considering climate change,intergovernmental cooperation,and public involvement.

Vulnerability and Conservation of Nearshore Cetaceans to Increasing Vessel Traffic:The Indo-Pacific Humpback Dolphin in the South China Sea

A comprehensive risk assessment to evaluate the vulnerability of the nearshore cetaceans to increasing marine traffic is lacking.In this study,the risk to Indo-Pacific humpback dolphins(Sousa chinensis)in the main habitats in China was assessed based on a semiquantitative spatial vulnerability analysis.85%of the(sub)population which overlapped with the lanes of ferries and/or cargo vessels,with exposure scores of 1.23±0.31(calculated based on the proportion of sea routes that overlap the dolphin’s range).A combination of high exposure to the sea routes and sensitivity to marine traffic would render the(sub)populations to be highly vulnerable(EPRE:5.21 and XM:4.47).A low frequency of vessels and an awareness of the ecology assures a low vulnerability(SH:2.43,EZ:2.73).Uncertainty scores were commonly lower for the higher vulnerable populations,and higher for the lower vulnerable populations,suggesting additional field data and more monitoring are necessary.Six years of field data have been used to analyze the influences of various types of marine traffic on humpback dolphin behavior.Fishing and non-fishing vessels were significantly different(χ^(2)=65.19,p<0.01).The humpback dolphins were attracted by fishing vessels(83.1%)but avoided non-fishing vessels(95.2%).We recommend a management with seasonal and geographical constraints,to balance economic development and environmental conservation.

Whistle signal variations among three Indo-Pacific humpback dolphin populations in the South China Sea:a combined effect of the Qiongzhou Strait’s geographical barrier function and local ambient noise?

Geographic variations in the dolphin whistles could be useful in assessing association and isolation among populations.Whistle of free-ranging Indo-Pacific humpback dolphins(Sousa chinensis)among the Pearl River Estuary(PRE),Leizhou Bei(LZB)and Sanniang Bay(SNB)populations were investigated.A total of 2850 whistles with legible fundamental contour were extracted and 15 acoustic parameters were measured.Contrary to SNB,PRE and LZB had the same relative proportion of tonal type compositions with flat and sine representing the most frequent types.The generalized linear model analysis showed significant acoustic difference among populations and tonal types.All frequency parameters in SNB were significantly higher than those in PRE and LZB,where no significant variation was observed in most of the parameters either at the population level or within each tonal type.Canonical discriminant functions analysis showed a smaller difference between PRE and LZB than between PRE and SNB and between LZB and SNB.Compared with previous recordings,recent recordings demonstrated a consistent pattern of becoming higher in whistle frequency parameters in both LZB and SNB populations,suggesting that noise pollution in LZB and SNB increasing with time according to the acoustic niche hypothesis.Dolphin whistle’s geographic variations could be shaped by the combined function of the geographical barrier function of the Qiongzhou strait and local ambient noise.Considering the isolated condition and the relatively smaller population size of the humpback dolphin in the SNB,more effective and proactive conservation actions should be taken to prevent the extinction of small populations.

Multilocus DNA metabarcoding diet analyses of small cetaceans:a case study on highly vulnerable humpback dolphins and finless porpoises from the Pearl River Estuary,China

Accurate diet identification of top predators is crucial to fully understand their ecological roles.Compared to terrestrial animals,gathering dietary information from cetaceans is notoriously difficult.Here,we applied a multilocus metabarcoding approach to investigate the diet of vulnerable Indo-Pacific humpback dolphins and Indo-Pacificfinless porpoises from the Pearl River Estuary(PRE),China.Our analyses identified 21 preyfish species from the 42 humpback dolphin stomachs,as well as 10 species offish and 1 species of cephalopod from the 13finless porpoise stomachs.All of the taxa were assigned to the species level,highlighting that the multimarker approach could facilitate species identification.Most of the prey species were small-and medium-sizedfishes that primarily fed on zooplankton.The calculated similarity index revealed a moderated dietary overlap between the 2 cetaceans,presumably due to the feeding of the 2 predators in association withfishing vessels in the PRE.A more diverse diet was observed in humpback dolphins in the closedfishing season compared to thefishing season,implying the influence on the dolphin diet due to the availability of commercialfishery resources.However,according to the results of species rarefaction curves,ourfindings on the feeding habits of the 2 cetaceans are still limited by insufficient sample size and therefore should be interpreted with caution.This study represents afirst attempt to apply the multilocus DNA metabarcoding technique in the diet analysis of small cetaceans,although more efforts are needed to improve this type of analysis.

The intestinal microbiome of an Indo-Pacific humpback dolphin(Sousa chinensis)stranded near the Pearl River Estuary,China

The mammalian intestinal microbiome is critical for host health and disease resistance.However,the cetacean intestinal microbiota remains relatively unexplored.By using high-throughput 16S rRNA gene sequencing,we analyzed intestinal bacterial samples from an Indo-pacific humpback dolphin(Sousa chinensis)stranded near the Pearl River Estuary in China.The samples included 3 anatomical regions(foregut,midgut,and rectum)and 2 anatomical locations(content and mucus).Our analyses revealed that the dolphin intestinal bacteria contained 139 operational taxonomic units(OTUs),dominated at the phyla level by Firmicutes(47.05%in the content;94.77%in the mucus),followed by Bacteroidetes(23.63%in the content;1.58%in the mucus)and Gammaproteobacteria(14.82%in the content;2.05%in the mucus).The intestinal bacteria had a small core community(15 OTUs,accounting for 99.74%of the reads),some of which could be potentially pathogenic to both human and dolphins.As an alternative to sampling the dolphin intestinal bacteria,fecal sampling could be used.Additionally,function potentials such as,xenobiotics biodegradation,beta-lactam resistance,and human disease-related pathways,were detected in the dolphin intestinal bacteria.These findings provide the first baseline knowledge of the intestinal microbiome of the Indo-Pacific humpback dolphin,which may offer new insights into cetacean conservation by using microbial surveillance.

Utilizing Occupancy Models and Platforms-of-Opportunity to Assess Area Use of Mother-Calf Humpback Whales

The Hawaiian Islands, and particularly the Maui 4-island region, are a critical breeding and calving habitat for humpback whales (Megaptera novaeangliae) belonging to the Hawaii distinct population segment. Our aims were to test the use of platforms-of-opportunity to determine trends in mother-calf pod use of the region and to present opportunistic platforms as an alternative method of long-term, cross-seasonal monitoring. Data were collected from whale watching vessels over a 4-year period and analyzed using occupancy models to determine the probability of habitat use of pods with calves and pods without calves within the study area. Detection probability was influenced by survey effort and month for all pod types with detection of adult only pods further influenced by year. Pods with a calf showed a preference for shallow (<100 meters) low latitude waters (<20.7°N), while pods without a calf preferred deeper waters (>75 meters). Results presented here align with previous work, both in Hawaii and in other breeding grounds, which show a distinct segregation of mothers with a calf from other age-classes of humpback whales. The need for long-term continuous monitoring of cetacean populations is crucial to ensure species conservation. Data collected aboard platforms-of-opportunity, as presented here, provide important insight on humpback whale spatial and temporal distribution, which are essential for species protection and management.

The biogeography of group sizes in humpback dolphins(Sousa spp.)

Humpback dolphins(Sousa spp.)are obligate shallow-water and resident species,and they typically live in fission–fusion societies composed of small-sized groups with changeable membership.However,we have scant knowledge of their behavioral ecology,starting with potential factors influencing inter-population variability of their group sizes.Here,we compiled a new global dataset of humpback dolphin group sizes based on 150 published records.Our data indicated an inter-specific consistency of group-living strategy among the 4 species in the Sousa genus,as these species preferred living in small-sized groups with a mean size of mostly no more than 10,a minimum size of single individual or small pairs,and a maximum size of several tens or≈100.In addition,we clearly showed the geographic variations in group sizes of humpback dolphins at a global scale.We found that the geographic variations in humpback dolphin group sizes were primarily associated with the latitude,sea surface temperature,and abundance.To conclude,our findings provide insights into social dynamics and socioecological trade-offs of humpback dolphins,and help better understand how these resident animals adapted to their shallow-water habitats from the perspectives of biogeography and socioecology.

珠江西部河口中华白海豚分布与环境因子的关系

2012年采用船基截线法在珠江口西部河口进行了中华白海豚(Sousa chinensis)调查,并同步对渔业资源和渔业环境要素进行了现场采样测定,以分析该水域中华白海豚空间分布与环境因子的关系。利用广义加性模型(GAM)分析了中华白海豚目击率与海况、水深、底层水温、盐度、pH值、溶解氧、游泳生物密度、捕食种密度和离岸距离等的关系。GAM模型对中华白海豚目击率分布的总偏差解释率为64.7%,游泳生物密度、水深、捕食种密度、离岸距离、底层水温等对中华白海豚的栖息地选择有较大的影响。模型分析结果显示:中华白海豚的活动与捕食种密度密切相关,但当捕食种密度达到一定程度时对海豚目击率的影响减弱,推测可能与食物较多时海豚逗留捕食时间减少有关;中华白海豚较为喜欢的水深在10m左右,这一模拟结果与以前的统计结果基本一致;中华白海豚对底层水温似乎有一定的选择性,当底层水温大于19.5℃时目击率明显下降,推测底层水温可能影响了捕食种鱼类的分布,进而影响海豚的活动;离岸距离3km范围内是中华白海豚较为喜欢的水域,因此对这一水域范围应给予重点保护管理。

北部湾儒艮现状的调查兼记印度洋白海豚

为了解北部湾中国水域儒艮的现状 ,于 2 0 0 0年 9月 15日至 11月 17日在广东、海南、广西三省区的沿岸海域进行了 36次舟船考察。调查结果表明 ,在北部湾的部分海域仍有儒艮存在 ,但数量比 2 0世纪 80年代已显著减少。建议把海南省西海岸近海的儒艮及其栖息地的保护作为最优先的海兽保护项目。另外在 11月 3日和 4日在广西壮族自治区北海市大风江口 (2 1°36′N ,10 8°5 4′E)的舟船考察中 ,还分别观察到约 7头和 4头印度洋白海豚的小群 ,它们属于在中国海域已知的唯一印度洋白海豚种群 ,建议广西合浦国家级儒艮自然保护区把印度洋白海豚也作为其重点保护对象之一。

中华白海豚3个MHC基因座位遗传变异的初步分析(英文)

主要组织相容性复合体(Major histocompatibility complex,MHC)基因是由一组紧密连锁的基因组成,是哺乳动物免疫系统中最重要的组成部分。本文选择3个MHC基因座位的第二外元,即:MHC-I类基因和II类基因的DRA和DQB座位,初步调查濒危物种中华白海豚的遗传变异。共鉴定了2个DRA、2个DQB和7个MHC-I等位基因。DRA座位遗传变异非常低,而DQB和MHC-I座位具有相对较高水平的遗传变异。并且,在DQB和MHC-I基因座位的假定的抗原结合位点(Antigen binding sites,ABS),非同义替代明显大于同义替代,提示平衡选择(Balancing selection)维持这两个座位的多态性,而在DRA座位上,并没有检测到平衡选择。系统发生分析表明中华白海豚的MHC等位基因没有聚在一起,而是和其他的物种聚在一起,符合MHC跨种进化(Transspecies evolution)的模式。

北部湾沙田水域中华白海豚和江豚的同域分布格局及时空变化

北部湾是中华白海豚和江豚的重要分布区,但是对该水域两物种的分布格局及时空变化的研究却比较少,也不清楚这两个物种分布区是否有重叠。2003～2004年与2011～2012年期间,我们在北部湾沙田水域进行了船只调查,总计航程4876.8km,收集了两个物种空间分布的数据。结果表明,2003～2004年仅发现中华白海豚,2011～2012年则同时发现了中华白海豚和江豚。与2003～2004年4～5月相比,中华白海豚在2011年4～5月份的遇见率明显增加(0.152vs0.028头次/km)。中华白海豚的MCP、95%FK家域和50%FK核心域面积分别为162.6km2、271.35km2和56.78km2,2011～2012年50%FK核心家域有所扩大且东移。江豚的MCP、95%FK家域和50%FK核心域面积分别为97.21km2、318.72km2和38.18km2。江豚主要分布于中华白海豚的外围远岸水域,同时两个物种的分布区有小部分重叠。基于多种因素的分析,我们推测,江豚可能存在季节性迁移以及中华白海豚对河口区有明显的偏好,可能是造成它们分布格局不同的原因。

中华白海豚(Sousa chinensis)组织中多氯联苯的研究

以珠江口海域的两头中华白海豚为研究对象,采用气相色谱法分析了海豚组织中多氯联苯(PCBs)的含量分布特征和毒性水平。结果表明,PCBs在海豚10种不同组织中的含量范围为25.1—85567.3ng/g,PCBs含量最高的组织为额隆和皮肤,其次为肝脏、肌肉、心脏、睾丸和脑,最低的为肺、胃和肾脏;PCBs同系物和同族物在海豚不同组织中的分布特征相似,同系物中以PCB101+113和PCB153所占总量的百分比最大,在10.25%—51.70%之间;在同族物中以含在同族物中以5个氯原子和6个氯原子的PCBs为主,所占百分比均在23.53%—60.06%之间;运用二毒性当量(TEQ)评价了中华白海豚不同组织中PCBs的毒性,其TEQs范围为55.9—68191.0pg/g,其中皮肤TEQs含量最高。TEQs主要来自非邻位取代的PCBs,占总量的74.15%—99.62%,其中来自PCB 126的占34.11%—96.51%。与世界其他海域海豚的PCBs污染水平相比,成年中华白海豚受PCBs污染严重,其体内的PCBs含量和毒性当量均已超出安全浓度范围,对其健康已造成威胁。

上川岛至海陵岛海域中华白海豚种群特征初探

珠江口中华白海豚(Sousa chinensis)种群从伶仃洋一直连续分布至上川岛海域。为探究上川岛以西海域是否也有中华白海豚分布,于2013-2015年采用船基截线法在上川岛至海陵岛海域进行了8个航次的考察。结果显示各个航次均有中华白海豚的目击记录,考察期共目击到78群次(约623头次),部分个体有重复目击记录,证实了该海域常年栖息着一定数量的中华白海豚。海豚的目击分布以下川岛、漭洲岛周围水域,以及东平港至庙湾角近岸水域较为集中。海豚的平均目击率与珠江东部河口(伶仃洋)和珠江西部河口区处于同一水平,海豚聚群规模较大并发现有大于30头的超大规模聚群,整体的年龄组成较为年轻化,表明上川岛至海陵岛海域是中华白海豚的重要栖息地,具有较好的保护潜力。

厦门海域两头中华白海豚体内微量元素的积累

对2004年4月在厦门海域搁浅死亡的两头中华白海豚(Sousa chinensis)进行了肝脏、胰、胃、肾、肠、肺、肌肉、心脏等多组织微量元素锌(Zn)、铜(Cu)、汞(Hg)、铅(Pb)、镉(Cd)和砷(As)浓度的测定。两豚各组织总体上必需元素Zn、Cu浓度高于有毒元素Hg、Pb、Cd和As。XM20040430体内特别高的Zn、Hg、Pb、Cd浓度分别出现于皮肤(500μg/g干重)、肝脏(255μg/g干重)、肺(13.0μg/g干重)和肾(2.82μg/g干重)中,而Cu和As在各组织中的浓度较为相似。XM20040429体内仅肝脏中Zn(448μg/g干重)和Cu(52.0μg/g干重)的浓度远高于其他组织。虽然两海豚微量元素的总体积累多低于急性毒性水平,但有毒元素Hg、Pb、Cd、As的明显检出和XM20040429肝脏中异常高的Zn浓度均显示出进一步研究微量元素慢性胁迫效应的必要性。结果还显示厦门港海域近年来Hg、Cd、Pb污染未见减轻,As也明显检出,必须引起高度重视。今后有关水生哺乳动物中As积累的研究也有待加强。

大襟岛海域中华白海豚栖息地重金属含量测定与评价

分别对中华白海豚栖息地的海水、表层沉积物和生物(鱼类、甲壳类和软体类动物)体中的重金属含量进行测定与污染评价.结果表明,海洋生物对海水和沉积物中重金属有较强的富集能力,中华白海豚其肝脏中高浓度的重金属含量是通过食物链(网)而逐级积累的.栖息地中海水质量介于海水I类与II类水质之间,表层沉积物质量符合I类标准,3类不同类群生物的体内重金属含量也均低于海洋环境质量生物污染评价标准,表明本海域尚未受到重金属污染,环境质量基本符合中华白海豚的生存要求.大襟岛海域的重金属水平落在整个珠江口海区的低值区,这可能是中华白海豚选择大襟岛海域作为栖息地的一个重要原因.

厦门海域两头中华白海豚体内铁的含量

Samples of liver,pancreas,stomach,kidney,intestine,lung,muscle,heart,skin,and brain from two stranded Indo-Pacific humpback dolphins(Sousa chinensis)near Xiamen harbor of China in April 2004 were analyzed for iron(Fe)concentration.The highest levels of Fe were found in the blood(2 471.0 μg/g,dry weight)and liver(2 968.2 μg/g,dry weight)of the animal XM20040429(female,body weight 86 kg,body length1.88 m,estimated age 2-3 year-old)and XM20040430(female,204 kg,2.45 m,4-5 year-old),respectively.In general,Fe concentrations were higher in blood,liver,lung,kidney and muscle than any other organs or tissues in both individuals,although there were obvious differences in body length,body weight and age between these two dolphins.This tissular distribution pattern of Fe concentration of Indo-Pacific humpback dolphins in the present study is similar to those of Dall’s porpoises(Phocoenoides dalli),finless porpoises(Neophocaena phocaenoides)and striped dolphins(Stenella coeruleoalba)in the previous literatures.

微波消解ICP-MS法测定中华白海豚额隆中微量元素及其含量特征分析

中华白海豚是我国一级保护动物,处于海洋食物链顶端,而重金属、持久性有机污染物等污染物易在其体内富集。额隆是鲸豚回声定位的重要部位,具有传导信号的作用。为探究中华白海豚额隆中微量元素的基线水平以及其组成的主要特征成分,研究采用微波消解电感耦合等离子体质谱(ICP-MS)法测定了中华白海豚额隆中V,Ni,Cr,Mn,Cu,As,Zn,Hg,Se,Cd和Pb 11种微量元素并对其含量进行特征分析。结果表明该方法具有良好的准确度和精密度,适合于中华白海豚额隆微量元素的测定分析。样品分析显示,额隆中11种微量元素整体含量水平不高,由于个体生理状况不同,同种元素含量在不同个体中存在差异;其平均含量从高到低排序依次为:Zn>As>Cu>Mn>Se>Hg>Cr>Ni>Pb>V>Cd,其中As作为非必需有毒微量元素,含量水平较高(1.158μg·g-1 ww),可能会对海豚产生生理毒害作用。Spearman相关性分析显示,As(r=0.733),Cd(r=0.615)和Hg(r=0.645)含量与海豚体长呈显著正相关性(p<0.05),表明As,Cd和Hg三种元素可随海豚年龄增加而在额隆中富集;Cs与Ni呈正相关(p<0.05),Mn与As呈负相关(p<0.01),表明元素间也存在着一定的关联性。此外,主成分分析结果表明,V,Mn,Ni,Se,Cu和Hg为中华白海豚额隆主要特征微量元素。研究在国内首次使用微波消解ICP-MS法对中华白海豚额隆中微量元素进行研究,结合相关性分析和主成分分析,有效探究了中华白海豚额隆中微量元素的生物富集模式与含量特征,实验结果为研究中华白海豚额隆中微量元素基线水平提供了参考。

氢化物发生-原子吸收光谱法测定中华白海豚中的汞和砷

采用氢化物发生-原子吸收光谱法对中华白海豚的多种组织和器官标本进行汞、砷浓度的测定。对样品的前处理方法和分析条件进行了探讨和优化。在优化的实验条件下,采用样品加标对Hg的测定方法进行验证,回收率为97%—104%。采用国家标准贻贝对As的测定方法进行验证,平均回收率为93%,RSD为7.8%。本法可用于贝类及其他水生动物的汞、砷的测定。

海洋污染对中华白海豚栖息地选择的影响研究

为了探索污染对海洋生物栖息地的影响,以2006—2007年中华白海豚在广西钦州三娘湾及其邻近海域的出现数据为基础,结合Google海洋地形数据、卫星遥感数据和2012年度海洋环境调查数据,构建干、湿季节海豚分布预测的最大熵模型,发现与主要河口的距离是决定海豚栖息地分布的最主要因素。比较基于不同环境变量的模型预测结果,发现海豚分布范围还受到水体营养盐和持久性污染物质的限制性影响,在干旱季节和湿润季节都出现预测栖息地面积缩小的现象。根据模型预测和比较结果,得到中华白海豚的栖息地选择策略:选择河口海域生活以获得丰富的鱼类食物,同时趋向于回避高污染风险的区域。研究结论对海洋保护区的选址及管理策略具有参考意义。

Distribution and conservation of the Indo–Pacific humpback dolphin in China

The Indo–Pacific humpback dolphin(Sousa chinensis Osbeck,1765)is a threatened species inhabiting the waters of China.Despite being of conservation concern,the distribution and abundance of this species has not been comprehensively evaluated.From 1994 to 2008 we performed over 14000 km of line-transect surveys and adminis-tered over 700 questionnaires to collect basic information on the geographic range and likely abundance of Indo–Pacific humpback dolphins along the southern and eastern coasts of China.Through our study we were able to establish a reporting network of stranding and incidental catches for this species.Our quantitative data suggests that only 76 animals remain around Xiamen,39 in the Hepu Nature Reserve and 114 in the estuary of the Dafengjiang River.Qualitative data from local fishing people and government officials suggests that dolphins may exist year-round in waters off Ningde and Shantou.We found that wild populations of Sousa chinensis in this important region are clearly being affected by human disturbance and habitat deterioration,including underwater blasting,vessel collision,fishing,aquaculture and water pollution.Although some protected areas have been established and this species is protected under Chinese law,there remains virtually no protection for this animal.