Transmission beam pattern and dynamics of a spinner dolphin (Stenella longirostris)

Author Posting. © Acoustical Society of America, 2019. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 145(6), (2019): 3595, doi:10.1121/1.5111347.Toothed whales possess a sophisticated biosonar system by which ultrasonic clicks are projected in a highly directional transmission beam. Beam directivity is an important biosonar characteristic that reduces acoustic clutter and increases the acoustic detection range. This study measured click characteristics and the transmission beam pattern from a small odontocete, the spinner dolphin (Stenella longirostis). A formerly stranded individual was rehabilitated and trained to station underwater in front of a 16-element hydrophone array. On-axis clicks showed a mean duration of 20.1 μs, with mean peak and centroid frequencies of 58 and 64 kHz [standard deviation (s.d.) ±30 and ±12 kHz], respectively. Clicks were projected in an oval, vertically compressed beam, with mean vertical and horizontal beamwidths of 14.5° (s.d. ± 3.9) and 16.3° (s.d. ± 4.6), respectively. Directivity indices ranged from 14.9 to 27.4 dB, with a mean of 21.7 dB, although this likely represents a broader beam than what is normally produced by wild individuals. A click subset with characteristics more similar to those described for wild individuals exhibited a mean directivity index of 23.3 dB. Although one of the broadest transmission beams described for a dolphin, it is similar to other small bodied odontocetes.The authors would like to thank the staff at Ocean Adventure for their time and assistance, Laura Kloepper for her assistance and advice on the data analysis, and Andy Solow for his help with the statistical analysis. The array system was originally designed by Stuart Ibsen. This work was funded by a research grant from the Sea World Busch Gardens Conservation Fund awarded to A.F.P. All work was conducted in compliance with University of Hawaii at Manoa IACUC and conducted under NMFS permit No. 16053 to P.E.N. This is contribution No. 1761 from the Hawaii Institute of Marine Biology.2019-12-1

Interactions Between Marine Megafauna and Plastic Pollution in Southeast Asia

Southeast (SE) Asia is a highly biodiverse region, yet it is also estimated to cumulatively contribute a third of the total global marine plastic pollution. This threat is known to have adverse impacts on marine megafauna, however, understanding of its impacts has recently been highlighted as a priority for research in the region. To address this knowledge gap, a structured literature review was conducted for species of cartilaginous fishes, marine mammals, marine reptiles, and seabirds present in SE Asia, collating cases on a global scale to allow for comparison, coupled with a regional expert elicitation to gather additional published and grey literature cases which would have been omitted during the structured literature review. Of the 380 marine megafauna species present in SE Asia, but also studied elsewhere, we found that 9.1 % and 4.5 % of all publications documenting plastic entanglement (n = 55) and ingestion (n = 291) were conducted in SE Asian countries. At the species level, published cases of entanglement from SE Asian countries were available for 10 % or less of species within each taxonomic group. Additionally, published ingestion cases were available primarily for marine mammals and were lacking entirely for seabirds in the region. The regional expert elicitation led to entanglement and ingestion cases from SE Asian countries being documented in 10 and 15 additional species respectively, highlighting the utility of a broader approach to data synthesis. While the scale of the plastic pollution in SE Asia is of particular concern for marine ecosystems, knowledge of its interactions and impacts on marine megafauna lags behind other areas of the world, even after the inclusion of a regional expert elicitation. Additional funding to help collate baseline data are critically needed to inform policy and solutions towards limiting the interactions of marine megafauna and plastic pollution in SE Asia

Interactions between marine megafauna and plastic pollution in Southeast Asia

Southeast (SE) Asia is a highly biodiverse region, yet it is also estimated to cumulatively contribute a third of the total global marine plastic pollution. This threat is known to have adverse impacts on marine megafauna, however, understanding of its impacts has recently been highlighted as a priority for research in the region. To address this knowledge gap, a structured literature review was conducted for species of cartilaginous fishes, marine mammals, marine reptiles, and seabirds present in SE Asia, collating cases on a global scale to allow for comparison, coupled with a regional expert elicitation to gather additional published and grey literature cases which would have been omitted during the structured literature review. Of the 380 marine megafauna species present in SE Asia, but also studied elsewhere, we found that 9.1 % and 4.5 % of all publications documenting plastic entanglement (n = 55) and ingestion (n = 291) were conducted in SE Asian countries. At the species level, published cases of entanglement from SE Asian countries were available for 10 % or less of species within each taxonomic group. Additionally, published ingestion cases were available primarily for marine mammals and were lacking entirely for seabirds in the region. The regional expert elicitation led to entanglement and ingestion cases from SE Asian countries being documented in 10 and 15 additional species respectively, highlighting the utility of a broader approach to data synthesis. While the scale of the plastic pollution in SE Asia is of particular concern for marine ecosystems, knowledge of its interactions and impacts on marine megafauna lags behind other areas of the world, even after the inclusion of a regional expert elicitation. Additional funding to help collate baseline data are critically needed to inform policy and solutions towards limiting the interactions of marine megafauna and plastic pollution in SE Asia

Dugongs and green turtles: grazers in the tropical seagrass ecosystem

This study examined aspects of the interactions between dugongs, green turtles and their tropical seagrass food. In order to examine the effects of herbivory on the community structure, productivity, and nutritional composition of seagrass, experiments simulating intensive and light dugong grazing (uprooting whole plants) and intensive turtle cropping (removal of aboveground biomass) were carried out in intertidal seagrass beds at Cardwell (18°14'S, 146°E) and Ellie Point (16 ° 53 S, 145 ° 46 ' E) on the northeast Queensland coast. Grazing experiments at Cardwell and Ellie Point were monitored monthly for a year before the seagrass samples were harvested. An additional short-term experiment was also carried out at Cardwell only, wherein samples were harvested one month and two months after cropping, while those from the grazing plots were harvested after four months. Seagrasses were harvested opportunistically from eight sites and from four depths at one site to investigate specific and spatial variation in nutrient composition. The effect of artificial nitrogen and phosphorus fertiliser treatments on seagrass nutrients was investigated experimentally at Shelley Beach (19°19'S, 146°50'E). Determinants of the nutritional composition of tropical seagrasses and the nutritional basis of the observed feeding preference of these herbivores were also considered. Two techniques were used in seagrass ecology for the first time: (1) Video recording was used for monitoring temporal changes in the species composition and abundance in tropical seagrass communities; (2) Near infra-red reflectance spectroscopy (NIRS) was used to measure the concentrations of the following: nitrogen, organic matter, neutral detergent fibre, acid detergent fibre, lignin, water soluble carbohydrate, and starch and in vitro digestibility of dry matter. The development of the NIRS technique involved the collection of 10 species of seagrasses: Halophila ovalis, H minor, H spinulosa, H decipiens, H. trichostata, Halodule uninervis, Cymodocea serrulata, C. rotundata, Syringodium isoetifolium, and Zostera capricorni (with H uninervis and Z capricorni exhibiting two varieties). From this collection, a seagrass database consisting of 1,165 samples of leaves (n = 556), roots/rhizomes (n = 552), whole plant (n = 11), seeds (n = 3), and detrital matter (n= 43), including the samples from the grazing experiments, was developed. Then, using NIRS, the spectra of all samples were collected. From this spectral population, some 200 spectra representative of the whole population were selected, using a computer algorithm package (NIRS 3) as the calibration set and prediction equations (multivariate models) developed for the above seagrass nutritional components. The nature and extent of the effects of grazing and cropping were related to: (1) the intensity of the grazing impact; and (2) the nature of the seagrass community, including its species composition and location. In a mixed-species bed at Ellie Point, intensive grazing altered the species composition by promoting the growth of a more opportunistic (short-lived) species, Halophila ovalis in the spaces created by the grazing disturbance at the expense of a long-lived species, Zostera capricorni. Grazing also reduced the amounts of detrital matter. The species composition of a monospecific bed of Halodule uninervis was not affected by grazing. Both light and intensive grazing, and cropping increased the net above-ground biomass productivity of H. ovalis and Halodule uninervis. Recovery times varied from months for H. ovalis and Zostera/Cymodocea at Ellie Point to more than one year for H uninervis at Cardwell. In both cases, grazing improved the seagrass bed as grazing habitat for dugongs and green turtles. Simulated dugong grazing improved the nutritional composition (nitrogen and water soluble carbohydrate) of H. ovalis and H uninervis. This improvement was detectable 10 to 12 months later. In short-term experiments, both grazing and cropping increased the leaf nitrogen concentration of H uninervis. The digestibility (in vitro) of dry matter of H uninervis moderately increased after grazing and cropping. Grazing and cropping had variable effects on the fibre and lignin contents of H. uninervis depending on the plant part, nature and intensity of herbivory and duration of the recovery. Enhanced nutrients in the sediments increased the concentrations of nitrogen, starch, and fibre of H minor and H uninervis. The nutritional composition of seagrasses also varied between plant parts, among species, between varieties, among depths, and among locations (sites). Halophila species, together with Syringodium isoetifolium, were more digestible than Z. capricorni, C. serrulata, and C. rotundata, while Halodule uninervis had the highest nitrogen and starch concentrations of any of the species. Dugongs and green turtles appear to optimise their diet by selecting food species that maximise digestible nutrients. This is achieved by selecting seagrass species that are more digestible and have higher nutrients (e.g. nitrogen and carbohydrates/starch) and/or species which can compensate for grazing. Changes in feeding habitats due to herbivory by dugongs and green turtles affect the functional dynamics of tropical seagrass ecosystems through the alteration of resource availability and sediment redox conditions resulting from grazing disturbance. Consequently, mosaics of patches of varying species and nutritional compositions are produced at a local scale. A major and long-term reduction in the number of dugongs and green turtles in some areas may lead to an irreversible degradation of their habitats as preferred food species are replaced by less-preferred species. In other areas, other forms of natural disturbance and environmental constraints probably maintain the community at a low seral stage

Protocols for collection of biological samples: Strengthening the efforts on marine mammal research in the Philippines

One of the major rationales for responding to stranded marine mammals, apart from the rescue component, is also the research potential these sorts of events offer. Various biological samples may be collected from live or dead marine mammals that can be utilized to strengthen and optimize the research opportunity on marine mammals in the Philippines. These samples can give us information about, but not limited to, their stranding events, health, life history parameters, population and molecular ecology, histopathology, infectious diseases and chemical contamination which can give us status and clues to many marine environmental changes since these animals are considered as one of the best sentinels for ocean health. However, in the Philippines, practical considerations in collecting blood, tissues and other pertinent samples are complicated by the logistics, and preservation and storage requirements to ensure appropriate studies. Recognizing the limitations in sample collection but still, aiming to improve Philippine marine mammal research, this paper (1) presents marine mammal sampling protocols and strategies suited for the country, and (2) establish these protocols as the standardized method that can be used by first responders, who are mainly members of Philippine Marine Mammal Stranding Network (PMMSN). These standardized methods will ultimately facilitate systematic and long-term monitoring program, provide a competitive edge for the country in producing high quality marine mammal research results. Furthermore, studying these animals will optimize utilization of samples from stranded marine mammals to further enhance knowledge regarding these species. The acquired information will ultimately be used in developing effective conservation measures for these understudied and undervalued animals

Sampling strategies and tissue biobank: Favoring quality and innovation for the Philippine Marine Mammal Research and Stranding Laboratory

Paramount to the future scientific usefulness of biological samples is the collection and storage procedure. This serves as the initial step to ensure the success of subsequent analyses and correct data interpretation. However, the lack to no information of proper sampling and storage protocols will have profound negative impact on the scientific results from possible integrative research opportunities in the Philippines where preponderance of marine mammal stranding events have been reported and recorded. Moreover, the multiple biological tissue samples which can be (1) collected from one of the best sentinels of ocean health and (2) optimized for further understanding of marine environmental changes will be deemed useless. Therefore, it is recommended to develop protocols targeting an improved Philippine marine mammal research. In this presentation, we describe (1) marine mammal tissue sampling strategies suited for the country, and recommended (2) establishment of systematized Philippine Marine Mammal Tissue Bank (PMMTB) which will be located in the Marine Mammal Research and Stranding Laboratory (MMRSL) of the Institute of Environmental Science and Meteorology (IESM), University of the Philippines Diliman (UPD). These sampling guidelines and storage research design will ultimately (1) facilitate systematic and long-term monitoring program, (2) provide a competitive edge for the country in producing high quality marine mammal research results, (3) optimize utility samples from stranded marine mammals, and (4) develop effective conservation measures. With the involvement of some government agencies such as BFAR and the Philippine Marine Mammal Stranding Network (PMMSN) regional chapters and stranding responders with the scientific advocacies of IESM’s MMRSL, the maintenance of a purposeful sample and data saturation will greatly maximize research productivity

A troubled top of the marine food chain: Ecotoxicological relevance and consideration to stranded cetaceans in Philippine waters

Anthropogenic contaminants such as polychlorinated biphenyls (PCBs), dichlorodiphenyltricloethanes (DDTs), heavy metals, and polycyclic hydrocarbons (PAHs) are continually being detected in various tissues of marine mammals in other parts of the world. Data correlating pollutant residues with altered reproductive and development states, liver disease, endocrine system damage, and alarming growth in cancer cases are reported for these marine top-level predators. If exposure has already been long-term, this may be more deterrent to a population’s continued success than a single, high-impact event. In the Philippines, there are data reporting the presence of these xenobiotics in almost all environmental media (sediments, soils, waters, mussels, fish, squids, and shrimps). Through the process of biomagnification, cetaceans found stranded in Philippine waters are greatly at risk. Moreover, reports show that these stranded cetaceans are used for human consumption in the country. Given these data, the high frequency of stranding events in the country are currently being maximized in an ecotoxicological, biomarker and histopathological research targeting at least 30 cetaceans found stranded (live and dead) in our waters. Findings of this pioneering study will be used to (1) provide knowledge & understanding of current contamination levels in these cetaceans, which are at the top of the food web, found stranded in Philippine waters, (2) educate our locals of possible human health impacts of cetacean consumption, and (3) present scientific data which will initialize development of ecotoxicological protocols in the Philippines using not just stranded cetaceans but also other marine mammal species or other marine species in general