Sperm whales in the waters off China:A glimpse of the past and present

Spatiotemporal information is crucial for cetacean research and conservation,particularly for wide-ranging and migratory species.Sperm whales(Physeter macrocephalus)are distributed worldwide in deep oceans;however,little is known about the species in the western margin of the Pacific Ocean.Here,we examined the available information related to the occurrence,distribution,and potential habitats of sperm whales in the waters off China.Historical whaling information(18th–20th century)indicates that sperm whales have been captured in the East China Sea(ECS)and South China Sea(SCS).Furthermore,sporadic strandings have been recorded since the 1910s,and more frequently from 1990 onwards.Since 1990,accidental sightings have been documented in the eastern ECS,northeastern and southern SCS,and their adjacent waters.More recently(2019–2022),field encounters have been reported in dedicated ship-based investigations in the Xisha and Nansha waters,providing robust evidence of the regular existence and potential residency of sperm whales in the northwestern and central areas of the SCS.Female nursery groups suggest that the Xisha waters might be an important nursing ground for sperm whales.Satellite tracking data from four adults showed that sperm whales in the SCS might display both fine-scale and long-distance movements.Taken together,it appears that sperm whales are currently active in the waters off China,and that deep waters(depth>200 m)in the ECS and SCS may provide the species with critical habitats.This review provides crucial baseline information on sperm whales in the waters off China,which may help to facilitate future research efforts and conservation initiatives for the species at national and cross-regional scales.More field investigations and other monitoring approaches including acoustic monitoring,biologging,photo-identification,and genetics are required to reveal the distribution,movement,and habitat use patterns of sperm whales in these waters.

Carboxymethyl chitosan as a polyampholyte mediating intrafibrillar mineralization of collagen via collagen/ACP self-assembly

The significant role of the polyelectrolytic nature of non-collagenous proteins (NCPs) in regulating the in vivo mineralization of collagen provides important insights for scientists searching for analogues of NCPs to achieve in vitro collagen mineralization. Polyampholyte carboxymethyl chitosan (CMC) has both carboxyl and amino groups, which allows it to act as a cationic or anionic polyelectrolyte below or above its isoelectric point (IP), respectively. In this study, CMC was employed as the analogue of NCPs to stabilize amorphous calcium phosphate (ACP) under acidic conditions (pH < 3.5) via the formation of CMC/ACP nanocomplexes. In the presence of both ACP nanoparticles and acid collagen molecules, ACP nanoparticles could be integrated into collagen fibrils during the process of collagen self-assembly and achieve intrafibrillar mineralization of collagen in vitro (i.e., synchronous self-assembly/mineralization (SSM) of collagen). This mode of mineralization is different from established mechanisms in which mineralization follows the self-assembly (MFS) of collagen. Thus, SSM provides a new strategy for developing materials from mineralized collagen scaffolds.

A pioneering survey of deep-diving and off-shore cetaceans in the northern South China Sea

A pioneering boat-based survey was conducted in 2019,to gather baseline information regarding the presence,composition,relative abundance,and spatial distribution of deep-diving and off-shore cetaceans in the northern South China Sea(SCS).A total of 27 sightings comprising at least 8 cetacean species were recorded during the 13-day survey,including 5 deep-diving species(i.e.Risso’s dolphin[Grampus griseus],short-finned pilot whale[Globicephala macrorhynchus],sperm whale[Physeter macrocephalus],Cuvier’s beaked whale[Ziphius cavirostris],and an unidentified beaked whale[either the ginkgo-toothed beaked whale,Mesoplodon ginkgodens,or Deraniyagala’s beaked whale,Mesoplodon hotaula]),as well as 3 off-shore dolphins(i.e.pantropical spotted dolphin[Stenella attenuate],striped dolphin[Stenella coeruleoalba],and Fraser’s dolphin[Lagenodelphis hosei]).With the exception of pantropical spotted dolphins,all other species were sighted and recorded at sea in the northern SCS for the first time.The pantropical spotted dolphin was the most frequently sighted species,comprising 30%of the total sightings.Deep-diving cetaceans were mainly sighted in the northern Xisha Archipelago,whereas off-shore dolphins were distributed across the survey area.The pantropical spotted dolphin was observed in aggregations of more than 100 individuals and nearly all encountered species included calves;these findings suggested that the survey area functions as an important feeding and calving ground for various cetacean species.This pioneering survey provides fundamental information regarding cetacean fauna in the northern SCS and highlights the need to strengthen research and conservation efforts concerning these species.

Doping bioactive elements into a collagen scaffold based on synchronous self-assembly/mineralization for bone tissue engineering

Pure collagen is biocompatible but lacks inherent osteoinductive,osteoimmunomodulatory and antibacterial activities.To obtain collagen with these characteristics,we developed a novel methodology of doping bioactive elements into collagen through the synchronous self-assembly/mineralization(SSM)of collagen.In the SSM model,amorphous mineral nanoparticles(AMN)(amorphous SrCO3,amorphous Ag3PO4,etc.)stabilized by the polyampholyte,carboxymethyl chitosan(CMC),and collagen molecules were the primary components under acidic conditions.As the pH gradually increased,intrafibrillar mineralization occurred via the self-adaptive interaction between the AMNs and the collagen microfibrils,which were self-assembling;the AMNs wrapped around the microfibrils became situated in the gap zones of collagen and finally transformed into crystals.Srdoped collagen scaffolds(Sr-CS)promoted in vitro cell proliferation and osteogenic differentiation of rat bone marrow mesenchymal stromal cells(rBMSCs)and synergistically improved osteogenesis of rBMSCs by altering the macrophage response.Ag-doped collagen scaffolds(Ag-CS)exhibited in vitro antibacterial effects on S.aureus,as well as cell/tissue compatibility.Moreover,Sr-CS implanted into the calvarial defect of a rat resulted in improved bone regeneration.Therefore,the SSM model is a de novo synthetic strategy for doping bioactive elements into collagen,and can be used to fabricate multifunctional collagen scaffolds to meet the clinical challenges of encouraging osteogenesis,boosting the immune response and fighting severe infection in bone defects.

First live sighting of Deraniyagala’s beaked whale(Mesoplodon hotaula)or ginkgo-toothed beaked whale(Mesoplodon ginkgodens)in the western Pacific(South China Sea)with preliminary data on coloration,natural markings,and surfacing patterns

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 3 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.ginkgodens 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.

Photo-identification comparison of four Indo-Pacific humpback dolphin populations off southeast China

Indo-Pacific humpback dolphins(Sousa chinensis)inhabit shallow coastal waters of the Indo-Pacific region including southeast China,with at least 6 putative populations identified to date in Chinese waters.However,the connectivity among these populations has not yet been fully investigated.In the present study,we compared and crossmatched 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 4 study areas.Furthermore,there was a notable difference in the pigmentation pattern displayed by individuals from these 4 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.

Cetacean occurrence and diversity in whale-watching waters off Mirissa,Southern Sri Lanka

Scientific information is vital to the conservation of cetaceans and the management of whale-watching activities.The southern coastal waters of Sri Lanka are near a narrow continental shelf and biologically abundant in cetacean species.Although the occurrence of cetaceans has been investigated in certain waters of Sri Lanka,few surveys have been conducted along the southern coast.To fill this gap,we conducted boat-based surveys from January to May 2017 to investigate the occurrence,diversity,and behavior of cetaceans in the waters off Mirissa,covering a survey area of 788.9 km2.During 55 survey days,we recorded a total of 242 cetacean sightings and identified at least 9 species(3 mysticetes and 6 odontocetes).The blue whale was the most common mysticete species(167 of 174 mysticete encounters),followed by the Omura’s whale(4 of 174)and Bryde’s whale(3 of 174).The spinner dolphin was the most common odontocete species(28 of 68 odontocete encounters),followed by the sperm whale(18 of 68),common bottlenose dolphin(13 of 68),short-finned pilot whale(5 of 68),melon-headed whale(2 of 68),and killer whale.Blue whales and sperm whales exhibited a clear preference for outer shelf and high slope areas,and blue whales were observed feeding along these waters.The present study provides near-baseline information on cetacean occurrence and diversity in whale-watching waters off southern Sri Lanka,and highlights the urgent need for proper management strategies for whale-watching activities.

Microbial diversity and structure in the gastrointestinal tracts of two stranded short-finned pilot whales(Globicephala macrorhynchus)and a pygmy sperm whale(Kogia breviceps)

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 2 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 3 whales were different.Our results revealed that the gut microbiome of 1 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.

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.