SPINNER DOLPHINS (STENELLA LONGIROSTRIS) OF THE WESTERN PACIFIC AND SOUTHEAST ASIA: PELAGIC AND SHALLOW-WATER FORMS1

A dwarf form of the spinner dolphin has been reported from the Gulf of Thailand, while more typical large spinner dolphins have been described from Japanese waters and other localities in the western Pacific. These reports have been based on very few specimens. Our purpose in this study was to determine the affinities of spinner dolphins throughout the region based on larger samples and to review their taxonomic status, with an hypothesis of two widespread ecotypic forms, or subspecies. We examined 213 osteological specimens, from a tuna gillnet fishery in the Philippines, from the former Taiwanese shark gillnet fishery in the Timor and Arafura Seas off northern Australia, from the Gulf of Thailand, from other areas in the western Pacific and Southeast Asia, from the eastern Indian Ocean, and from the Central and South Pacific. Results show that spinner dolphins from the deep inner waters of the Philippines conform to the large pelagic type of spinner dolphin that inhabits the Central and South Pacific, the western Pacific and the eastern Indian Ocean. The skull is similar in size and shape to the holotype specimen of S. longirostris (from unknown locality). This form feeds primarily on small mesopelagic fishes and squids. Spinner dolphins from the shallow waters of inner Southeast Asia represented in the sample, including the Gulf of Thailand, Timor Sea and Arafura Sea, are smaller in body and skull size, have fewer teeth and vertebrae, and feed mainly on benthic and coral reef fishes and invertebrates. We hypothesize that this form also inhabits the Java Sea and other shallow waters throughout inner Indonesia and Malaysia. We redescribe a subspecies corresponding to the small form and based on Delphinus roseiventris Wagner 1846 from the Arafura Sea, designating a neotype and paraneotype specimens.     

Model-specific selection of molecular targets for heart failure gene therapy

Heart failure (HF) is a complex multifaceted problem of abnormal ventricular function and structure. In recent years, new information has been accumulated allowing for a more detailed understanding of the cellular and molecular alterations that are the underpinnings of diverse causes of HF, including myocardial ischemia, pressure-overload, volume-overload or intrinsic cardiomyopathy. Modern pharmacological approaches to treat HF have had a significant impact on the course of the disease, although they do not reverse the underlying pathological state of the heart. Therefore gene-based therapy holds a great potential as a targeted treatment for cardiovascular diseases. Here, we survey the relative therapeutic efficacy of genetic modulation of β-adrenergic receptor signaling, Ca(2+) handling proteins and angiogenesis in the most common extrinsic models of HF.     

CRANIAL SEXUAL DIMORPHISM AND GEOGRAPHIC VARIATION IN ERASER'S DOLPHIN, LAGENODELPHIS HOSEI

Knowledge of geographic variation is important to questions of population assessment and management. Fraser's dolphins have been exploited in two regions in the western Pacific. Analysis of 137 skulls from the Philippines, Japan, Taiwan, Australia, Indonesia, Malaysia, South Africa, France, the U.S., St. Vincent and the Grenadines, and the eastern tropical Pacific revealed sexual dimorphism in 5 of 26 measurements (difference of 1.9%-5.8% between males and females), similar to levels of cranial dimorphism in other small pelagic delphinids. Males had a larger braincase and temporal fossae and smaller external nares than females. Sexually dimorphic characters were excluded, and male and females samples were pooled to examine geographic differences in the remaining characters. Multivariate analyses yielded significant differences between the Philippine and Japanese series within the North Pacific and between a pooled North Pacific series and a North Atlantic series. The Japanese skulls were on average broader and had a wider rostrum, larger orbit, larger internal nares, and longer braincase than the Philippine skulls. These differences suggest that Fraser's dolphins exploited in Japanese and Philippine waters in directed fisheries or as by catch belong to different populations and should be assessed and managed separately.     

COMPARATIVE FEEDING ECOLOGY OF SPINNER DOLPHINS (STENELLA LONGIROSTRIS) AND FRASER'S DOLPHINS (LAGENODELPHIS HOSEI) IN THE SULU SEA

Fraser's and spinner dolphins are known to feed on mesopelagic prey, bur their diets and feeding ecologies have not been compared in areas where they are observed together. In this study we examined the stomach contents of both species caught incidentally in a driftnet fishery for tuna in the eastern Sulu Sea. Importance of prey items was determined using the percent occurrence, percent number, and volumetric methods. Mesopelagic fishes, particularly myctophids (mainly Ceratoscopelus warmingi, Diaphus spp. and Myctophum asperum ), were the most important component in the diet of spinner dolphins, whereas in Eraser's dolphins, mesopelagic cephalopods ( Abraliopsis, Onychoteuthis, Histioteuthis , and Chiroteuthis ), and crustaceans ( Notostomos elegans, Acanthephyra quadrispinosa , and Acanthephyra carinata ) appeared to be equally important as the myctophid species. Fraser's dolphins appeared to feed preferentially on larger prey and had more diversified prey (Shannon's diversity index = 1.2) than spinner dolphins (diversity index = 0.9). Vertical distributions of the prey items summarized from published literature indicate that spinner dolphins forage in the upper 200 m and probably occasionally to as deep as 400 m, whereas Fraser's dolphins have a wider vertical foraging range, from near the surface to probably as deep as 600 m.     

Commentary on Coram et al. (2021) on the use of Facebook to understand marine mammal stranding issues in Southeast Asia

We reviewed Coram et al. (Biodivers Conserv 30:2341–2359, 2021, https://doi.org/10.1007/s10531-021-02196-6), a paper that highlights the use of social media data to understand marine litter and marine mammals in Southeast Asia. While we commend its intent, we find that the methodology used and conclusions drawn portray an incomplete and inaccurate perception of how strandings, stranding response, and analysis of stranding data have been conducted in the region. By focusing on investigative results revealed by a very limited search of one social media platform (Facebook), using only English keywords, and insufficient ground-truthing, Coram et al. (2021) have, unintentionally, given the perception that Southeast Asian scientists have not conducted even the bare minimum of investigation required to better understand the issue of marine litter and its impact on marine mammals. In this commentary we provide a more accurate account of strandings research in Asia and include recommendations to improve future studies using social media to assess conservation issues.