Understanding Cetacean Community Composition and Distribution in Lakshadweep Waters, Northern Indian Ocean

Panicker, Divya University of Washington ProQuest Dissertations & 2022 해외박사(DDOD)

The Northern Indian Ocean (NIO) is a region of high environment variability driven by seasonally reversing winds. The southwest monsoons generate substantial plankton blooms in these tropical waters and shape biogeography of higher trophic levels. Cetaceans in oceanic waters are good indicators of epipelagic and mesopelagic prey bases. This dissertation examines species composition and distribution of cetaceans in a mid-oceanic island habitat in southeastern Arabian Sea. I use passive acoustic monitoring (PAM), which is particularly useful to collect data year-round including night periods and the rough-weather southwest monsoon season when visual surveys are challenging. In Chapter 2, I examine the occurrence and species composition of the cetacean community in the Lakshadweep archipelago via visual surveys using a platform of opportunity. The surveys documented 139 sightings, including eight odontocete species and one mysticete species. Occurrence of cetacean species differed across seafloor slope gradients and distances to nearest landmass. In Chapter 3, I investigate baleen whale occurrence in Lakshadweep waters using PAM. The study showed occurrence of Central Indian Ocean (CIO; formerly Northern Indian Ocean) acoustic population of blue whales in Indian waters. These results extend the known range of CIO pygmy blue whales about 1000 km north-westward from the waters surrounding Sri Lanka. In Chapter 4, I determined the occurrence and temporal patterns of island-associated odontocetes in Lakshadweep waters using PAM. A resident population, likely to be spinner dolphins, was identified. Whistle occurrence was significantly influenced by month, site, and diel and lunar cycles. Similarities of odontocete occurrence to other mid-oceanic island chains suggest that an island-associated micronekton community may exist around Lakshadweep. In Chapter 5, I characterize dominant sound sources to the shallow water reef soundscape in Lakshadweep and their correlation with local oceanographic parameters across monsoon and non-monsoon months. Four acoustic bands of interest, namely a geophonic band of wind-driven wave sounds and three biophonic bands containing animal choruses, are presented. Low frequency biophonic choruses peaked in inter-monsoon months, while low frequency geophonic sound levels peaked during monsoon months. Choruses showed site-wise variability and correlation with sea surface salinity, chlorophyll-a, and wind speed. Understanding cetaceans and the underwater soundscape through an oceanographic lens highlight the underlying biological resources and physical drivers in this poorly studied area. This dissertation demonstrates that employing appropriate technology and methodologies can shed light on even highly mobile species (such as blue whales) in challenging conditions. Within the context of a changing climate, the information presented here can provide a baseline to compare with future cetacean and soundscape studies in this region. Furthermore, the dissertation emphasizes that current plans for tourism development in these islands need to incorporate potential impacts on near-island cetacean communities and on underwater noise.

Detection of a novel cetacean papillomavirus in a common dolphin in Jeju island, Republic of Korea

한세진 서울대학교 대학원 2020 국내석사

Papillomaviruses are oncogenic DNA viruses that infect epithelial and mucosal cells. To date more than 140 papillomaviruses with a proven capacity to infect humans and animals have been identified. Usually papillomaviruses form a balanced relationship with the host, such that the lesion does not progress to cause serious clinical problems. Notably however, cases of malignant transformation of benign tumors have been reported in several animal species, such as cattle, rabbits and dogs. In recent decades, papillomavirus has been detected in free-ranging marine mammals in the North Sea of the Atlantic Ocean and the Southeast Pacific Ocean. Cetacean papillomavirus should be monitored constantly because it may affect the population dynamics of each host species by negatively affecting reproduction. Furthermore, the association of malignant transformation of papillomavirus infection in Atlantic bottlenose dolphin has been recently proposed. This report describes the case of a common dolphin that was found dead with proliferative skin lesions. Necropsy revealed enlarged mesenteric lymph node, left adrenal gland and left testis. Skin histopathology revealed typical characteristics of papilloma, incuding hyperkeratosis, koilocytosis, ballooning degeneration and inclusion bodies. In the testis and lymph node, multiple pleomorphic cells with abundant fibrous connective tissues were observed. Sequenced PCR products were closely related to Omikronpapillomavirus spp. isolated from the common bottlenose dolphin and Burmeister’s porpoise. To our knowledge, this is the first report of oral and genital papillomatosis with concurrent metastatic neoplasia in common dolphin. The present study suggests that further investigations should focus on isolation of viruses and determination of their pathogenic potential. The distribution and emergence of papillomaviruses in Korean coastal common dolphin populations and the role of the virus as a possible cause of mortality should also be studied in the respect of conservation of marine ecosystem. 파필로마바이러스는 DNA 바이러스로써, 상피와 점막층에 감염하여 종양을 발생시킬 수 있다. 현재까지 140여종 이상이 사람과 동물에 감염한다고 알려져 있으며 보통 피부 병변에 국한되고 파필로마나 사마귀 같은 양성 종양을 형성한다. 하지만 드물게 악성 종양으로 변이를 나타내기도 하는데, 동물에서는 소, 토끼 그리고 개에서 그러한 변이가 보고된 바 있다. 지난 20년간 10여종의 야생 고래류에서 파필로마바이러스가 확인되었으나 보고 지역은 대서양 북해와 태평양 남동해로 한정적이었다. 선행 연구에 따르면 해양포유류 파필로마바이러스 관련 질병의 임상 증상으로는 피부 및 점막 병변이 특징적이었지만 최근 만성 파필로마의 악성 변이 가능성이 대두되기도 했다. 본 연구에서는 한국의 제주도 해역에서 좌초하여 발견된 참돌고래의 증식성 피부병변에서 분리된 해양포유류 파필로마바이러스에 대한 연구 분석 결과를 보고한다. 피부병변 시료에서 PCR을 통해 얻어진 파필로마바이러스의 L1 gene이 검출되었으며, 이는 계통학적으로 Indian Liver Lagoon bottlenose dolphin에서 검출된 Omikronpapillomavirus 1 과 가장 유사한 것으로 확인되었다. 피부 병변의 조직병리학적 소견은 koilocytosis, ballooning degeneration, hyperkeratosis를 보였으며, 이는 파필로마바이러스 감염에 의해 나타날 수 있는 전형적인 소견이다. 좌측 고환 종괴에서는 핵대소부동과 세포대소부동이 보이는 다양한 형태의 Sertoli cell이 다수 관찰되었으며 장간막림프절 종괴에서도 비슷한 양상의 세포가 다수 관찰되었다. 본 연구는 아시아에서 최초로 해양포유류 파필로마바이러스를 분리하고 그 특성을 분석하였다는데 의의를 두고 있다. 또한 파필로마바이러스와 전이성 종양의 연계 가능성을 고찰하고자 하였다. 나아가 향후 한국 해역에 서식하는 해양포유류에서의 해당 바이러스의 분포 정도를 확인하고 잠재적인 병원성을 규명하는 등 추가 연구가 지속적으로 이루어져야 함을 제안한다.

Investigation of In-Vivo Integument Mechanics for Device Design at the Bio-Mechanical Interface

Yang, Dory Y University of Michigan ProQuest Dissertations & Th 2023 해외박사(DDOD)

The term "bio-mechanical interface" refers to the point where living organisms interact with mechanical devices. This connection often leads to varying degrees of discomfort due to force interactions and impedance differences between the two entities. Two primary strategies to alleviate this discomfort involve modifying contact conditions or adapting behaviors. Wearable sensors, a subset of bio-mechanical interfaces, have gained significant attention as technology advances. These embedded systems, affixed directly to the body, are becoming smaller, more efficient, and increasingly integrated into our daily lives.Bio-logging tags, a specific type of wearable sensor, have proven invaluable for tracking and studying animals across diverse habitats. Particularly useful for observing cetacean behavior, these tags have illuminated the activities of animals spending most of their lives underwater and traversing vast ocean expanses. Over the past two decades, suction cups have emerged as a widely employed method for temporarily attaching bio-logging tags to marine creatures such as whales, dolphins, and turtles. Suction attachment is especially beneficial when long-term invasive tagging is inappropriate due to factors like tag longevity, animal size, health condition, or tag recovery requirements. These suction cup tags are affixed to free-swimming animals using poles or ballistic delivery methods, with the smooth skin of marine mammals facilitating secure attachment. Their non-penetrative attachment and versatility across various species make suction cup tags indispensable tools for minimally invasive research.However, in both field studies and from the collected data, tag issues such as early detachment, sliding from the original spot, or animals actively trying to get rid of the tag are common. These phenomena not only significantly affect the reliability of the collected data, but also raise questions about how much disturbance these tags cause and how the suction cup design can be improved.This dissertation centers on addressing the following research questions:Q1: How does cetacean integument respond to vacuum loading?Q2: What factors contribute to suction cup failure?Q3: How can suction cup design be improved to achieve prolonged attachment, minimal motion, and reduced discomfort?As a bio-mechanical experimentalist, I tackle these research questions in my PhD work. I begin by creating a custom optical measurement instrument called the PDIC (Portable Digital Image Correlation) system, which enables in-vivo investigation of cetacean integument. Using this system, I extract the viscoelastic properties of the skin and identify the parameters necessary for a viscoelastic model that can accurately capture the skin's deformation response under vacuum loading.Following this, I establish a generalized kinetic model for suction cups and characterize their attributes, including linear stiffness and area composition. I then conduct experiments to test different suction cup designs and determine their corresponding loading limits before failure. Utilizing the new knowledge gained from the in-lab investigation, I integrate pressure transducers into bio-logging tags to create a new device, pressure-logging tag, that can monitor suction cup states in the real world. My work will conclude with a proposed suction cup design framework, which includes key decision variables, environmental parameters, and performance indices that can serve as a foundation for improving suction cup design for the future.

First Report of Gammaherpesvirus Skin Infection in Narrow-ridged Finless Porpoise (Neophocaena asiaeorientalis) in Korea

이성빈 서울대학교 대학원 2022 국내석사

Narrow-ridged finless porpoise (Neophocaena asiaeorientalis) is one of the endemic and dominant cetacean species in Korean seawater. However, the population of the species has been decreased sharply in for the last 10 years. Accordingly, narrow-ridged finless porpoise was included as Endangered in the red list of the International Union for the Conservation of Nature (IUCN) in 2017. Despite the risk of extinction, pathological research of the porpoise has rarely been reported yet. To prevent population declines of the species, conservation medicine should be studied more for the health of wildlife, ecosystem, and human. In this study, I examined and detected a viral pathogen from infected skin of a narrow-ridged finless porpoise. A carcass of female narrow-ridged finless porpoise was stranded on the beach located at Jeju Island, South Korea. Twelve dermatitis lesions were spread on various sites of the body. The results of histopathological examination of the skin lesions indicated moderately to markedly thickened epidermis with accentuated rete pegs, amorphous eosinophilic material in the vacuoles, eosinophilic intranuclear inclusion bodies in the epidermal cells, and marked infiltrates of predominantly mononuclear cells within the dermis. Extracted DNA from the skin lesions and mammary gland were amplified respectively with multiple primers of herpesvirus, papillomavirus, Lacazia loboi, and poxvirus to do rule out diagnosis. Consequently, gammaherpesvirus was detected in the molecular analysis. The viral sequence contains same parts with the partial DNA polymerase gene of Balaenoptera acutorostrata gammaherpesvirus 2, dwarf sperm whale gammaherpesvirus, and Blainville’s beaked whale gammaherpesvirus. Gammaherpesvirus has been usually reported as the pathogen of genital and oral mucosae infections in cetaceans, and the skin infection has been rarely reported. This study is the first report of gammaherpesvirus infection in narrow-ridged finless porpoise in the Republic of Korea. Besides, additional studies should be required on the latent infection status of the herpesvirus in the narrow-ridged finless porpoise and the spread of the herpesvirus in the Korean sea. 상괭이는 한국의 토종 돌고래이자 한국 바다의 우점종으로 잘 알려진 고래이다. 그러나 최근 10년 동안 상괭이의 개체수는 크게 감소하였으며, 그 결과 상괭이는 2017년 국제자연보전연맹(IUCN)의 적색 목록에서 절멸 위기(Endangered)에 처한 동물로 등록되었다. 이러한 멸종 위기에도 불구하고, 상괭이의 병리학적 연구는 아직까지 보고된 바가 많지 않다. 상괭이의 개체수 감소를 넘어 야생동물, 인간, 생태계의 건강을 위해 상괭이 보존 의학이 앞으로 더 연구되어야 할 것으로 보인다. 필자는 상괭이의 피부병에서 바이러스성 질병체를 검출하고, 연구한 내용을 이번 논문을 통해 보고하고자 한다. 암컷 상괭이 사체 하나가 한국 제주도 구좌읍에 위치한 해안가에서 발견되었다. 이 상괭이의 전신에는 약 20여개의 피부병변 부위가 산재해 있었다. 해당 병변의 조직학적 검사 결과 상으로 현저하게 두꺼워진 상피와 길어진 망융선을 관찰할 수 있었고, 그 외에 다수의 액포 형성 및 액포 내 무정형 호산성 물질, 진피 세포 내 호산성 핵내 봉입체, 진피 내 무수히 많은 단핵세포의 침투 등이 특이적이었다. 조직 검사 결과 허피스바이러스, 파필로마바이러스, 라카지아 로보이, 폭스바이러스 등이 해당 피부병의 병인체로 의심되어 피부 병변부에서 DNA를 추출하고, 각 병인체의 프라이머들을 이용하여 DNA를 증폭하였으며, 배제진단 방식으로 진단하였다. 최종적으로 DNA 시퀀스 분석 결과 이 피부병변에서는 감마허피스바이러스의 DNA 중합효소 유전자가 검출되었다. 해당 바이러스 DNA 시퀀스에는 상괭이와 같은 고래목에 속하는 밍크고래, 꼬마향고래, 혹부리고래에서 검출된 감마허피스바이러스와 동일한 시퀀스를 일부 갖고 있음을 PCR 및 유전자 분석을 통해 확인할 수 있었다. 감마허피스바이러스는 고래에서 주로 생식기 점막 또는 구강 점막에 질병을 일으키는 원인체로 알려져 있고, 피부 병변을 일으킨다는 보고는 거의 없었다. 이번 연구는 한국 상괭이에서 피부 질환을 유발하는 감마허피스바이러스를 최초로 보고하는 것에 그 의의가 있다. 또한, 상괭이의 허피스바이러스 잠복감염 실태, 한국 바다의 허피스바이러스 전파 양상 등이 추가적으로 연구되어야 할 것으로 보인다.

Endo-parasites and pathologic findings in narrow-ridged finless porpoise (Neophocaena asiaeorientalis) habiting in Korean seas

김선민 서울대학교 대학원 2020 국내박사

상괭이(Neophocaena asiaeorientalis)는 동아시아에 분포하는 소형 쇠돌고래이다. 최근 그 개체수가 급감하며 멸종위기종으로 분류되고 있다. 한국 바다는 현재 가장 많은 수의 상괭이가 서식하는 곳으로 최근 몇 년간 종 보전을 위한 여러 연구가 수행되어 왔다. 하지만 상괭이의 감염성 질병에 대한 국내 연구는 전무한 상황이다. 상괭이의 기생충성 질병에 대한 분석을 위해 2016년부터 2019년까지 4년 동안 총 107마리의 상괭이를 부검하여 여러 장기의 내부기생충을 채집하였다. 이 기생충들을 기생 부위별로 나누어 형태학적, 유전학적인 방법으로 종 동정을 실시하였다. 총 8종의 선충 (Parurus asiaeorientalis, P. sunameri, Stenurus nanjingensis, Halocercus pingi, H. sunameri, H. taurica, Anisakis pegreffii and Crassicauda magna)과 6종의 흡충 (Nasitrema sunameri, N. spathulatum, N. dalli, Campula oblonga, Synthesium tursionis and S. nipponicum)과 한 종의 조충 (Diphyllobothrium fuhrmanni)이 동정되었다. 이 중 N. dalli와 S. nipponicum은 상괭이 감염의 첫 보고이다. 각 기생충의 유병률은 숙주의 체장, 즉 성장 단계과 유의미한 관련이 있었으며, 이를 통해 H. pingi와 Crassicauda를 제외한 모든 종이 먹이원을 통해 감염되는 것으로 추정된다. 동, 남, 서해의 세 지역에 따른 유병률 차이 및 성별에 따른 유병률 차이는 모든 종에서 유의하지 않은 것으로 드러났다 (P>0.05). 기생충 감염은 숙주의 건강 상태, 질병, 좌초 행동 및 더 나아가 집단의 생존에 영향을 미칠 수 있다. 멸종 위기인 상괭이의 종 보전을 위해 기생충이 숙주에 미치는 영향을 정확히 판단하는 것은 매우 중요하다. 내부 기생충 감염으로 인한 병리적 병변이 발생한 조직에 대하여 육안 및 조직학적 분석을 실시한 결과, 위에서는 궤양, 미란, 출혈, 울혈, 색소 침착, 점막 비후, 박리, 경화, 천공과 과각화 및 위염 등의 다양한 증상이 발견되었다. 간에서는 육아종성 병변 및 담관 벽 비후가 주로 나타났으며, 유선에서는 결절 및 선충 감염에 의한 것으로 추정되는 상피근종 소견이 보였다. 폐에 기생하는 선충은 석회화 결절, 울혈, 기종, 수종 등의 육안적 소견과 기관지 폐렴 및 다발성 기관지염 등의 조직병리학적 소견을 보였다. 이 중 Halocercus pingi는 어미로부터 수직감염되는 것으로 추정되며, 중감염되는 경우 신생 동물의 호흡을 방해해 생존에 치명적인 영향을 미치는 것으로 판단된다. 이 종의 정확한 감염 기전을 밝히기 위해서는 태아에의 감염 또는 유즙 내 충란의 존재를 확인해야 한다. 기생충이 숙주에 미치는 병리적 영향에 대한 보다 정확한 분석을 위해서는 각 기생충의 정확한 생활사 규명이 수반되어야 할 것이다. 바다에 서식하는 기생충 중 가장 많은 연구가 이루어져 비교적 그 정보가 많은 아니사키스 종에 대한 계통분류학적, 계통지리학적 분석을 실시하였다. 동해, 남해 및 서해의 세 해역에서 수집한 상괭이의 위에서 검출된 아니사키스는 모두 Anisakis pegreffii로 동정되었다. 각 해역별로 30마리씩, 총 90마리의 A. pegreffii 세 유전자 (ITS, rrnS 및 cox2) 시퀀스를 분석한 결과, 두 종류의 미토콘드리아 유전자 (rrnS, cox2)의 유전적 다양성은 높은 편이나 핵 유전자 (ITS)는 단 하나의 하플로타입을 나타내었다. 세 해역간의 집단 구조는 없는 것으로 밝혀졌다. 다양한 숙주를 가지는 아니사키스의 간접 생활사 및 세 해역을 분리할만한 지형적 장애물이 없는 지리적 특징이 아니사키스의 유전자 흐름을 원활하게 하는 요인으로 분석된다. 보다 정확한 요인 분석을 위해 아니사키스 속의 중간숙주인 어류, 두족류 및 종숙주인 다른 해양 포유류의 국내 아니사키스 감염 현황에 대한 종합적인 연구가 추가적으로 이루어져야 할 것으로 생각된다. 세 유전자 중 분화 정도가 가장 높은 미토콘드리아 cox2 유전자를 Genbank에 등록된 세계 여러 해역의 하플로타입과 비교 분석하였다. 그 결과, 한국을 포함한 전 세계의 하플로타입은 크게 두 그룹으로 나뉘었으며 물리적 거리에 비례하는 유전적 거리와 panmixia가 동시에 나타나는 경향을 보였다. 한국 바다에 서식하는 상괭이의 내부기생충을 동정하고 숙주의 성장 단계, 성별 및 서식 해역에 따른 유병률을 조사하여 전체적인 감염 현황을 정리하였다. 상괭이의 위, 장, 간, 폐, 두개골 내 공간, 유선 및 근육 등 다양한 내부 장기에는 선충, 흡충 및 조충이 감염되어 있었다. 대부분의 기생충들은 성장 단계에 따라 식이성으로 감염되는 것으로 확인되었다. 몇 종의 기생충은 상괭이의 건강 상태에 위협이 되고 있다. 멸종 위기에 처한 상괭이의 종 보전을 위해 보다 광범위하고 체계적이며 지속적인 모니터링이 절실히 필요하다. The narrow-ridged finless porpoise (Neophocaena asiaeorientalis) is a small porpoise distributed in East Asia from Taiwan to Japan. The largest number of narrow-ridged finless porpoises inhabit the Korean seas. Several studies were performed to aid the conservation of the species there. However, research on infectious diseases was not performed for this species in Korea. Therefore, parasitic infestations in this species were studied as the first step of research on infectious diseases in narrow-ridged finless porpoises captured in the seas around the Korean peninsula. The narrow-ridged finless porpoises are classified as an endangered species because the population has recently declined sharply in all the countries they inhabit, including Korea, Japan, and China. The purpose of this study is to collect basic biological information about the species which is the most numerous and common in Korean seas, using analyses of parasites as an ecological indicator. During five years (2016 - 2019), a total of 107 narrow-ridged finless porpoises were dissected to examine parasitogenic diseases. The endo-parasites were collected from their organs and tissues during dissection. The collected parasites were classified according to the collected organ, morphological characteristics, and phylogenetic groups. Eight species of nematodes (Parurus asiaeorientalis, P. sunameri, Stenurus nanjingensis, Halocercus pingi, H. sunameri, H. taurica, Anisakis pegreffii and Crassicauda magna) and six species of trematodes (Nasitrema sunameri, N. spathulatum, N. dalli, Campula oblonga, Synthesium tursionis and S. nipponicum) and one cestode species (Diphyllobothrium fuhrmanni) were identified. Two trematodes, N. dalli and S. nipponicum, were first recorded from this porpoise species in this study. The parasite prevalence was significantly related with total body length of the host (in terms of growth stage), suggesting that the porpoise are infected with the parasites except H. pingi and C. magna, through taking food in the seas. The relationship between prevalence of the parasites and sea sector or host sex was not statistically significant (p>0.05). The parasitic infections in the narrow-ridged finless porpoise should be comprehensively surveyed to conserve more effectively this endangered species. The parasitic infections caused gross and pathological lesions in the stomach such as ulcer, erosion, hemorrhage, congestion, mottled macular pigmentation, mucosal hypertrophy, desquamation, solidification, perforation, hyperparakeratosis, and gastritis. In the liver, granuloma and hyperplasia of the bile duct wall were frequently observed. In the mammary glands, solid nodules and myoepithelioma were found. Lung nematodes were found provking the calcified nodules, congestions, emphysema and edema and also histopathological lesions such as bronchopneumonia and multifocal bronchitis. The lungworm, H. pingi was considered to be infected vertically from dam to fetus or calf. When heavily infected, it could be lethal to the neonates by disturbing breathing. To elucidate a mode of infection of this species, infection in fetus and/or existence of eggs in milk of the dam should be investigated. The complete life cycle of each parasite should be investigated for a more accurate examination of the pathological effect on the host species. Phylogenetic and phylogeographical analyses of Anisakis which has been intensively studied compared with other marine parasites were carried out. All nematodes from the stomachs of narrow-ridged finless porpoises inhabiting the three sea sectors of the Korean peninsula—the East sea, the Southern sea, and the Yellow sea—were identified as A. pegreffii. Three genes of 30 worms each from the sea, 90 worms in total were sequenced and analyzed. The mitochondrial genes were highly diverse, while the nuclear genes were conserved, showing only one haplotype in one gene. No genetic population structure among the three sea sectors was found. The indirect life cycle of A. pegreffii which has various intermediate and definitive hosts was analyzed as the factors that facilitate gene flow of A. pegreffii. The topographical features of Korean waters, which have no geographical barrier to separate the three seas were also could make high gene flow of A. pegreffii. A more accurate factor analyses would require a comprehensive examination of the infectious status of the genus Anisakis in other species, including fishes and cephalopods as intermediate hosts, and other final cetacean hosts. The most differentiated gene among the three genes, mitochondrial cox2 gene were compared with haplotypes from worldwide oceans registered in Genbank. The haplotypes of worldwide oceans including the Korean haplotypes from this study were largely divided into two groups. Both of genetic distance related to geographical distance and panmixia of haplotypes were observed. Collectively, this study clarified infection status of the endo-parasites in the narrow-ridged finless porpoises in Korean seas. The narrow-ridged finless porpoises were infected with nematodes, trematodes and cestode in various internal organs. Most of the helminth species were found to infect to the hosts by preying related to growth stage. Several parasite species were found to be fatal to the health status of the narrow-ridged finless porpoises. More extensive, systematic and continuous monitoring are strongly needed for conservation of the species.

Estimating the Cost of Locomotion in Common Bottlenose Dolphins: Calibration, Validation, and Application to Study the Impacts of Disturbance

Allen, Austin Stone ProQuest Dissertations & Theses Duke University 2021 해외박사(DDOD)

Estimates of the energetic costs of locomotion (COL) are necessary to understand one of the potential impacts of anthropogenic disturbance on marine mammals. A new generation of biologging devices has enabled the measurement of fine-scale behavioral responses to disturbance, but calibration experiments are required to convert these measured changes in activity level into energy expenditure. Such calibrations have been conducted in many terrestrial and avian taxa but, due to logistical constraints, have been performed with only a few marine mammals. Very few studies have tested these calibrations against independent estimates of energy expenditure, such as measurements of caloric intake and the doubly labeled water (DLW) method. Calibration studies will help us to better understand how best to estimate energy expenditure from activity measurements. In my dissertation, I ask whether short-term increases in activity caused by disturbance may impact marine mammal energy budgets. I address this question with the long-term resident community of common bottlenose dolphins (Tursiops truncatus) living in Sarasota Bay, Florida, which experiences very high levels of traffic from small vessels. I first correlated overall dynamic body acceleration (ODBA) and energy expenditure with bottlenose dolphins in human care. I combined measurements of ODBA derived from accelerometry tags with respirometry during submerged swim trials. I then subtracted measured resting metabolic rate (RMR) from the energy expenditure of each trial to estimate COL. I found a linear relationship between ODBA and COL. Next, I deployed tags on the same dolphins for longer periods (24 hours) and combined COL, RMR, and specific dynamic action (SDA; energy expenditure associated with digestion) to estimate total daily energy expenditure. I compared this estimate of total daily expenditure with estimates derived from measurements of caloric intake records and DLW. The COL+RMR+SDA values largely agreed with the calories ingested, but the smaller DLW sample was considerably more variable. I then used the correlation between ODBA and COL to estimate the cumulative energetic costs associated with responses to vessels by wild dolphins in Sarasota. I analyzed 12 digital acoustic tag (DTAG) records for the presence or absence of vessels. I used periods without vessels as controls to calculate baseline estimates of COL for each animal. I then subtracted this baseline from total COL to derive the cumulative COL attributable to vessels. The overall increase in COL attributable to the response to vessels was less than 0.3% of estimated daily energy expenditure, suggesting that avoidance, while necessary to prevent injury or death, does not contribute significantly to the daily energy budgets of these dolphins. The methods I developed can be applied to a variety of other marine mammals to study the fitness consequences of anthropogenic disturbance. Future studies should focus on sensitive species that are likely to exhibit significant avoidance responses to acoustic stimuli.