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.     

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.     

中国大陆沿岸水域首次发现布氏鲸

布氏鲸主要分布在太平洋、大西洋和印度洋的暖温水域。布氏鲸与鳀鲸因其外形极其相似,以往没有将其严格区分,中国黄海、东海、南海海域发现的主要是鳀鲸。2011年1月19日在山东日照市东港区一海滩搁浅1头雌性须鲸,媒体曾报道为长须鲸。我们根据其外形特征不同于长须鲸,其头骨顶部的鼻骨、前颌骨和上颌骨末端额鼻突形状不同于鳀鲸和长须鲸,而鉴定为布氏鲸,是中国大陆沿岸水域首次发现。该标本体长13.40 m,系成体,颅基长330 cm,脊椎式为C7＋T 13＋L 14＋Ca 21=55。本文主要报道了布氏鲸的外部形态和骨骼特征。     

Evidence of Brucella infection in marine mammals in the North Atlantic Ocean.

Between 1983 and 1996 a total of 1386 samples of serum were taken from four species of seal and three species of whale in the waters west of Iceland, the area of pack-ice north-west of Jan Mayen, the northern coast of Norway and the Kola Peninsula, the waters west of Svalbard, and the Barents Sea; they were tested for the presence of anti-Brucella antibodies with an indirect ELISA (protein G conjugate). The positive sera were re-tested with classical brucellosis serological tests, such as the serum agglutination test, the EDTA-modified serum agglutination test, the Rose Bengal test, and the complement fixation test, as well as an anti-complement ELISA. Anti-Brucella antibodies were detected in all the species investigated, except for the bearded seal (Erignathus barbatus), with the following prevalences: hooded seals (Cystophora cristata) 35 per cent; harp seals (Phoca groenlandica) 2 per cent; ringed seals (Phoca hispida) 10 per cent; minke whales (Balaenoptera acutorostrata) 8 per cent; fin whales (Balaenoptera physalus) 11 per cent; and sei whales (Balaenoptera borealis) 14 per cent. An isolate belonging to the genus Brucella was obtained from the liver and spleen of one of the seropositive minke whales. The findings suggest that antibodies against the surface lipopolysaccharide of Brucella species are widely distributed among marine mammals in the North Atlantic Ocean.     

Size and Shape Variability in the Skull of the Bottlenose Dolphin,Tursiops truncatus (Montagu, 1821)

The bottlenose dolphin (Tursiops truncatus) is a widely spread cetacean species. We present a quantitative analysis of age dimorphism variation in the skull of T. truncatus assessed by geometric morphometrics (GM) methods. Differences in size and shape of skulls were investigated using eight landmarks plotted on 2‐D images of ventral views of 14 museum specimens. The results of GM revealed differences in size, but not in shape. The left side appears more variable, which is probably an effect of telescoping.     

中国水域喙鲸类的研究

中国水域发现的喙鲸科中柯氏喙鲸、贝氏喙鲸、银杏齿中喙鲸、柏氏中喙鲸和朗氏中喙鲸等5种喙鲸的形态鉴别特征及其在中国的分布概况,其中柯氏喙鲸为中国内地沿岸鲸类新记录,朗氏中喙鲸为中国水域（包括台湾）鲸类新记录。     

Bartonella species detection in captive, stranded and free-ranging cetaceans

We present prevalence of Bartonella spp. for multiple cohorts of wild and captive cetaceans. One hundred and six cetaceans including 86 bottlenose dolphins (71 free-ranging, 14 captive in a facility with a dolphin experiencing debility of unknown origin, 1 stranded), 11 striped dolphins, 4 harbor porpoises, 3 Risso's dolphins, 1 dwarf sperm whale and 1 pygmy sperm whale (all stranded) were sampled. Whole blood (n = 95 live animals) and tissues (n = 15 freshly dead animals) were screened by PCR (n = 106 animals), PCR of enrichment cultures (n = 50 animals), and subcultures (n = 50 animals). Bartonella spp. were detected from 17 cetaceans, including 12 by direct extraction PCR of blood or tissues, 6 by PCR of enrichment cultures, and 4 by subculture isolation. Bartonella spp. were more commonly detected from the captive (6/14, 43%) than from free-ranging (2/71, 2.8%) bottlenose dolphins, and were commonly detected from the stranded animals (9/21, 43%; 3/11 striped dolphins, 3/4 harbor porpoises, 2/3 Risso's dolphins, 1/1 pygmy sperm whale, 0/1 dwarf sperm whale, 0/1 bottlenose dolphin). Sequencing identified a Bartonella spp. most similar to B. henselae San Antonio 2 in eight cases (4 bottlenose dolphins, 2 striped dolphins, 2 harbor porpoises), B. henselae Houston 1 in three cases (2 Risso's dolphins, 1 harbor porpoise), and untyped in six cases (4 bottlenose dolphins, 1 striped dolphin, 1 pygmy sperm whale). Although disease causation has not been established, Bartonella species were detected more commonly from cetaceans that were overtly debilitated or were cohabiting in captivity with a debilitated animal than from free-ranging animals. The detection of Bartonella spp. from cetaceans may be of pathophysiological concern.     

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.     

Community-based population monitoring for large baleen whales: the case study of Bryde's whale in Beibu Gulf of China

Citizen science is a popular method for the long-term monitoring of the distribution of wild animals. The application of these methods in different species and environments still poses challenges, especially for aquatic animals. In this study, we investigated the distribution of the Bryde's whale (Balaenoptera edeni) in the Beibu Gulf of China by using scientific boat-based surveys and citizen science approaches using 2 different methods of data collection. First, we built our mobile app (Whale Guard) and installed it on fishermen's phones. Second, we used a popular instant messaging app (WeChat) to create an online fisherman community. We found that the mobile phone app collected far fewer reports (5 reports) than the online community group (42 reports, P < 0.01). By using a variety of incentives, we maintained the fisherman's community's activity without significant user loss (P < 0.01). We also found that the locations collected by social media applications in this study were consistent with observations from scientific boat-based transect surveys. The sightings distribution of Bryde's whales differed from those in previous surveys in that they were present across larger areas. Social media apps reported that 69% of reports was confirmed by more than one person, whereas Whale Guard reports were much lower (0, P <0.001). Community-based citizen science can greatly contribute to the long-term monitoring of Bryde's whales, and it has successfully overcome the challenges of data accessibility, accuracy, and fragmentation. Our study shows how to appropriately use citizen science in different community groups and community-based approaches make them useful for large baleen whale surveys.     

A new chelonibiid from the Miocene of Zanzibar (Eastern Africa) sheds light on the evolution of shell architecture in turtle and whale barnacles (Cirripedia: Coronuloidea)

The fossil history of turtle and whale barnacles (Coronuloidea: Chelonibiidae, Platylepadidae, Coronulidae and †Emersoniidae) is fragmentary and has only been investigated in part. Morphological inferences and molecular phylogenetic analyses on extant specimens suggest that the roots of whale barnacles (Coronulidae) are to be found among the chelonibiid turtle barnacles, but the hard-part modifications that enabled early coronuloids to attach to the cetacean skin are still largely to be perceived. Here, we reappraise a fossil chelonibiid specimen from the Miocene of insular Tanzania that was previously referred to the living species Chelonibia caretta. This largely forgotten specimen is here described as the holotype of the new species †Chelonibia zanzibarensis. While similar to C. caretta, †C. zanzibarensis exhibits obvious external longitudinal parietal canals occurring in-between external longitudinal parietal septa that abut outwards to form T-shaped flanges, a character so far regarded as proper of the seemingly more derived Coronulidae and Platylepadidae. Along with these features, the presence of a substrate imprint on the shell exterior indicates that †C. zanzibarensis grasped its host's integument in much the same way as coronulids and platylepadids, albeit without the development of macroscopic parietal buttresses and bolsters. Thin section analyses of the inner parietal architecture of some extant and extinct coronuloids conclusively demonstrate that vestiges of comparable external parietal microstructures are present in some living members of Chelonibiidae. This observation strengthens the unity of Coronuloidea while significantly contributing to our understanding of the evolution of the coronuloid shell structure in adapting to a diverse spectrum of hosts.     

Parasites of cetaceans stranded on the Pacific coast of Costa Rica

Information regarding parasitic fauna of cetaceans from Costa Rica is provided for the first time. A total of 25 stranded dolphins and whales were examined between 2001 and 2009, including striped dolphin (Stenella coeruleoalba) (n=19), pantropical spotted dolphin (S. attenuata) (n=2), spinner dolphin (S. longirostris) (n=1), bottlenose dolphin (Tursiops truncatus) (n=1), dwarf sperm whale (Kogia sima) (n=1) and Cuvier's beaked whale (Ziphius cavirostris) (n=1). Pathological findings associated with the parasites are also presented. In the most representative dolphin species, S. coeruleoalba, the prevalence of parasites was 89.5%; moreover, all examined specimens of S. attenuata, S. longirostris, T. truncatus and Z. cavirostris presented parasites. No parasites were recovered from K. sima. Fourteen helminth taxa were identified, including six species of cestodes (Strobilocephalus triangularis, Tetrabothrius forsteri, Trigonocotyle sp., Phyllobothrium delphini, Monorygma grimaldi, Tetraphyllidea gen. sp. plerocercoid), four digeneans (Nasitrema globicephalae, Brachycladium palliatum, B. pacificum and Oschmarinella albamarina) and four nematodes (Anisakis spp., Halocercus lagenorhynchi, Halocercus sp. and Crassicauda anthonyi). A commensal crustacean, Xenobalanus globicipitis, was also identified. All identified parasites representing new geographic records for the Pacific coast of Central America and new host records are presented. Parasitological information is valuable for conservation of cetaceans in Pacific coast of Costa Rica.     

Diel differences in blue whale (Balaenoptera musculus) dive behavior increase nighttime risk of ship strikes in northern Chilean Patagonia

The northern Chilean Patagonia region is a key feeding ground and a nursing habitat in the southern hemisphere for blue whales (Balaenoptera musculus). From 2014 to 2019, during 6 separate research cruises, the dive behavior of 28 individual blue whales was investigated using bio-logging tags (DTAGs), generating ≈190 h of data. Whales dove to significantly greater depths during the day compared to nighttime (day: 32.6 ± 18.7 m; night: 6.2 ± 2.7 m; P < 0.01). During the night, most time was spent close to the surface (86% ± 9.4%; P < 0.01) and at depths of less than 12 m. From 2016 to 2019, active acoustics (scientific echosounders) were used to record prey (euphausiids) density and distribution simultaneously with whale diving data. Tagged whales appeared to perform dives relative to the vertical migration of prey during the day. The association between diurnal prey migration and shallow nighttime dive behavior suggests that blue whales are at increased risk of ship collisions during periods of darkness since the estimated maximum ship draft of vessels operating in the region is also ≈12 m. In recent decades, northern Chilean Patagonia has seen a large increase in marine traffic due to a boom in salmon aquaculture and the passenger ship industry. Vessel strike risks for large whales are likely underestimated in this region. Results reported in this study may be valuable for policy and mitigation decisions regarding conservation of the endangered blue whale.     

Structure and functions of the placenta in common minke (Balaenoptera acutorostrata), Bryde’s (B. brydei) and sei (B. borealis) whales

The structure and functions of placentas were examined in 3 species of rorqual whales, common minke (Balaenoptera acutorostrata), Bryde’s (B. brydei) and sei (B. borealis) whales, with the aim of confirming the structural characteristics of the chorion, including the presence of the areolar part, and clarifying steroidogenic activities and fetomaternal interactions in the placentas of these whales. Placentas were collected from the second phase of the Japanese Whale Research Program under Special Permit in the North Pacific (JARPN II). Histological and ultrastructural examinations revealed that these whale placentas were epitheliochorial placentas with the interdigitation of chorionic villi lined by monolayer uninucleate cells (trophoblast cells) and endometrial crypts as well as folded placentation by fold-like chorionic villi. Moreover, well-developed pouch-like areolae were observed in the placentas, and active absorption was suggested in the chorionic epithelial cells of the areolar part (areolar trophoblast cells). Berlin blue staining showed the presence of ferric ions (Fe³⁺) in the uterine glandular epithelial cells and within the stroma of chorionic villi in the areolar part. An immunohistochemical examination revealed tartrate-resistant acid phosphatase (TRAP; known as uteroferrin in uteri) in the cytoplasm of glandular cells and areolar trophoblast cells. This result suggested that, in cetaceans, uteroferrin is used to supply iron to the fetus. Furthermore, immunoreactivity for P450scc and P450arom was detected in trophoblast cells, but not in areolar trophoblast cells, suggesting that trophoblast cells synthesize estrogen in whale placentas. Therefore, we herein immunohistochemically revealed the localization of aromatase and uteroferrin in cetacean placentas during pregnancy for the first time.     

Expression and functional characterization of killer whale (Orcinus orca) interleukin-6 (IL-6) and development of a competitive immunoassay

Interleukin-6 (IL-6) is a cytokine that can reach detectable systemic levels and is a major inducer of the acute phase response. As such, clinical assays to identify this cytokine in mammalian sera are of diagnostic value. A 558 base-pair (bp) fragment of killer whale IL-6 was cloned and expressed as a 21 kDa protein in Escherichia coli. Biological activity of the recombinant killer whale IL-6 (rkwIL-6) was demonstrated using the IL-6-dependent B9 mouse hybridoma cell line; acute phase sera from a killer whale and supernatants from lipopolysaccharide (LPS)-stimulated killer whale peripheral blood mononuclear cells (PBMCs) also supported the proliferation of the B9 hybridoma. Rat anti-mouse IL-6 receptor antibody effectively blocked biological activity of all three sources of IL-6. Polyclonal antisera, specific for the recombinant protein, were obtained by successive immunization of a rabbit with rkwIL-6. The polyclonal antibody was capable of neutralizing the biological activity of both recombinant and native kwIL-6. A competitive enzyme-linked immunosorbent assay (ELISA) was developed using the polyclonal rabbit anti-rkwIL-6 and the recombinant protein; sensitivity of the assay was in the range of 1 ng/ml. The ELISA was subsequently used to identify the presence of native IL-6 in acute phase sera of two species of delphinidae, a killer whale and a bottlenose dolphin. The application of quantitative cytokine assays as diagnostic tools for monitoring cetacean health are becoming feasible as many animals are now being trained for fluke presentation, making blood collection a routine procedure.     

The rough-toothed dolphin genome provides new insights into the genetic mechanism of its rough teeth

The rough-toothed dolphin (Steno bredanensis) is characterized by having teeth covered in finely wrinkled vertical ridges, which is a general manifestation of amelogenesis imperfecta. The rough surfaces are hypothesized to be an evolutionary morphological trait of feeding adaptation to increase the dolphin's grip on prey. Here, we assembled a rough-toothed dolphin genome and performed the comparative genomic analysis to reveal the genetic basis of the special enamel. Results showed that genes related to enamel development or dental diseases have undergone diversified adaptive changes that may shape the special enamel morphology of this dolphin species, including positive selection (CLDN19, PRKCE, SSUH2, and WDR72), rapid evolution (LAMB3), or unique amino acid substitutions (AMTN, ENAM, MMP20, and KLK4). Meanwhile, the historical demography of rough-toothed dolphin indicated several distinct population fluctuations associated with climate change. The genome-wide heterozygosity of this dolphin is in the middle of all published data for cetaceans. Although the population is considerable, there may be population or subspecies differentiation, and with the global warming and the increasing disturbance of human activities, we should pay more attention to protection in the future. Together, our study brings new insights into the genetic mechanisms that may have driven the evolution of the special enamel morphology in rough-toothed dolphins and provides the first results of genetic heterozygosity and population historical dynamics of this species, which have important guiding implications for the conservation of this dolphin species.     

Four odontocete species change hearing levels when warned of impending loud sound

Hearing sensitivity change was investigated when a warning sound preceded a loud sound in the false killer whale (Pseudorca crassidens), the bottlenose dolphin (Tursiops truncatus), the beluga whale (Delphinaperus leucas) and the harbor porpoise (Phocoena phocoena). Hearing sensitivity was measured using pip‐train test stimuli and auditory evoked potential recording. When the test/warning stimuli preceded a loud sound, hearing thresholds before the loud sound increased relative to the baseline by 13 to 17 dB. Experiments with multiple frequencies of exposure and shift provided evidence of different amounts of hearing change depending on frequency, indicating that the hearing sensation level changes were not likely due to a simple stapedial reflex.     

Validation of a Field Based Chromatin Dispersion Assay to Assess Sperm DNA Fragmentation in the Bottlenose Dolphin (Tursiops truncatus)

Over the last two decades, there have been significant advances in the use of assisted reproductive technology for genetic and reproductive management of captive dolphin populations, including evaluation of sperm DNA quality. This study validated a customized sperm chromatin dispersion test (SCDt) for the bottlenose dolphin (Tursiops truncatus) as a means of assessing sperm DNA damage both in the field and in the laboratory. After performing the SCDt, two different sperm morphotypes were identified: (i) sperm with fragmented DNA showed large haloes of dispersed DNA fragments emerging from a compact sperm nucleoid core and (ii) sperm containing non‐fragmented DNA displayed small compact haloes surrounded by a dense core of non‐dispersed DNA and protein complex. Estimates of sperm DNA fragmentation by means of SCDt were directly comparable to results obtained following a two‐tailed comet assay and showed a significant degree of correlation (r = 0.961; p < 0.001). This investigation also revealed that the SCDt, with minor modifications to the standard protocol, can be successfully conducted in the field using a LED florescence microscopy obtaining a high correlation (r = 0.993; p = 0.01) between the data obtained in the laboratory and in the field.     

Experiential and Learning Desires of Whale Watching Guides Versus Tourists in Bahía de Banderas,Puerto Vallarta,Mexico

Whales are popular tourism attractions in many coastal areas of the world. Although not without disagreement, vessel-based whale viewing is widely considered to be a form of ecotourism, in which experiential and learning opportunities exist to engender pro-environmental awareness and behavior. Guides are considered to play an important interpretive role in this respect, although there is little research that explores what guides themselves desire to impart to their passengers. Using quantitative and qualitative methods, we compared what whale watching guides in Puerto Vallarta, Mexico (n = 9) desire their passengers experience and learn to that reported by the whale watchers themselves (n = 283). Guides placed a higher importance on education, while whale watchers indicated experiential elements such as viewing whales close up and spectacular behaviors. Furthermore, the guides held a strong view that emotional feelings of respect and love for whales were important for whale watchers to experience and learn about marine conservation.