scholarly journals How Do Marine Mammals Manage and Usually Avoid Gas Emboli Formation and Gas Embolic Pathology? Critical Clues From Studies of Wild Dolphins

2021 ◽  
Vol 8 ◽  
Author(s):  
Andreas Fahlman ◽  
Michael J. Moore ◽  
Randall S. Wells
Keyword(s):  
Marine Mammals ◽  
Bottlenose Dolphins ◽  
Gas Bubbles ◽  
Theoretical Models ◽  
Anatomy And Physiology ◽  
Terrestrial Mammals ◽  
Deep Diving ◽  
Cardiorespiratory Function ◽  
Sarasota Bay ◽  
Excised Tissues

Decompression theory has been mainly based on studies on terrestrial mammals, and may not translate well to marine mammals. However, evidence that marine mammals experience gas bubbles during diving is growing, causing concern that these bubbles may cause gas emboli pathology (GEP) under unusual circumstances. Marine mammal management, and usual avoidance, of gas emboli and GEP, or the bends, became a topic of intense scientific interest after sonar-exposed, mass-stranded deep-diving whales were observed with gas bubbles. Theoretical models, based on our current understanding of diving physiology in cetaceans, predict that the tissue and blood N2 levels in the bottlenose dolphin (Tursiops truncatus) are at levels that would result in severe DCS symptoms in similar sized terrestrial mammals. However, the dolphins appear to have physiological or behavioral mechanisms to avoid excessive blood N2 levels, or may be more resistant to circulating bubbles through immunological/biochemical adaptations. Studies on behavior, anatomy and physiology of marine mammals have enhanced our understanding of the mechanisms that are thought to prevent excessive uptake of N2. This has led to the selective gas exchange hypothesis, which provides a mechanism how stress-induced behavioral change may cause failure of the normal physiology, which results in excessive uptake of N2, and in extreme cases may cause formation of symptomatic gas emboli. Studies on cardiorespiratory function have been integral to the development of this hypothesis, with work initially being conducted on excised tissues and cadavers, followed by studies on anesthetized animals or trained animals under human care. These studies enabled research on free-ranging common bottlenose dolphins in Sarasota Bay, FL, and off Bermuda, and have included work on the metabolic and cardiorespiratory physiology of both shallow- and deep-diving dolphins and have been integral to better understand how cetaceans can dive to extreme depths, for long durations.

Spectral-tuning mechanisms of marine mammal rhodopsins and correlations with foraging depth

2000 ◽  
Vol 17 (5) ◽  
pp. 781-788 ◽  
Author(s):  
JEFFRY I. FASICK ◽  
PHYLLIS R. ROBINSON
Keyword(s):  
Amino Acid ◽  
Marine Mammal ◽  
Molecular Basis ◽  
Marine Mammals ◽  
Visual Pigments ◽  
Amino Acid Substitutions ◽  
Spectral Tuning ◽  
Long Wavelength ◽  
Terrestrial Mammals ◽  
Deep Diving

It has been observed that deep-foraging marine mammals have visual pigments that are blue shifted in terms of their wavelength of maximal absorbance (λmax) when compared to analogous pigments from terrestrial mammals. The mechanisms underlying the spectral tuning of two of these blue-shifted pigments have recently been elucidated and depend on three amino acid substitutions (83Asn, 292Ser, and 299Ser) in dolphin rhodopsin, but only one amino acid substitution (308Ser) in the dolphin long-wavelength-sensitive pigment. The objective of this study was to investigate the molecular basis for changes in the spectral sensitivity of rod visual pigments from seven distantly related marine mammals. The results show a relationship between blue-shifted rhodopsins (λmax ≤ 490 nm), deep-diving foraging behavior, and the substitutions 83Asn and 292Ser. Species that forage primarily near the surface in coastal habitats have a rhodopsin with a λmax similar to that of terrestrial mammals (500 nm) and possess the substitutions 83Asp and 292Ala, identical to rhodopsins from terrestrial mammals.

scholarly journals Total energy expenditure of bottlenose dolphins (Tursiops truncatus) of different ages

2021 ◽  
Author(s):  
Rebecca Rimbach ◽  
Ahmad Amireh ◽  
Austin Allen ◽  
Brian Hare ◽  
Emily Guarino ◽  
...  
Keyword(s):  
Energy Expenditure ◽  
Total Energy ◽  
Body Mass ◽  
Tursiops Truncatus ◽  
Marine Mammals ◽  
Bottlenose Dolphins ◽  
Large Body ◽  
Total Energy Expenditure ◽  
Natural Seawater ◽  
Terrestrial Mammals

Marine mammals are thought to have an energetically expensive lifestyle because endothermy is costly in marine environments. However, measurements of total energy expenditure (TEE; kcal/day) are available only for a limited number of marine mammals, because large body size and inaccessible habitats make TEE measurements expensive and difficult for many taxa. We measured TEE in 10 adult common bottlenose dolphins (Tursiops truncatus) living in natural seawater lagoons at two facilities (Dolphin Research Center and Dolphin Quest) using the doubly labeled water method. We assessed the relative effects of body mass, age, and physical activity on TEE. We also examined whether TEE of bottlenose dolphins, and more generally marine mammals, differs from that expected for their body mass compared to other eutherian mammals, using phylogenetic least squares (PGLS) regressions. There were no differences in body mass or TEE (unadjusted TEE and TEE adjusted for fat free mass (FFM)) between dolphins from both facilities. Our results show that Adjusted TEE decreased and fat mass (FM) increased with age. Different measures of activity were not related to age, body fat or Adjusted TEE. Both PGLS and the non-phylogenetic linear regression indicate that marine mammals have an elevated TEE compared to terrestrial mammals. However, bottlenose dolphins expended 17.1% less energy than other marine mammals of similar body mass. The two oldest dolphins (>40 years) showed a lower TEE, similar to the decline in TEE seen in older humans. To our knowledge, this is the first study to show an age-related metabolic decline in a large non-human mammal.

scholarly journals Field energetics and lung function in wild bottlenose dolphins, Tursiops truncatus , in Sarasota Bay Florida

2018 ◽  
Vol 5 (1) ◽  
pp. 171280 ◽  
Author(s):  
A. Fahlman ◽  
M. Brodsky ◽  
R. Wells ◽  
K. McHugh ◽  
J. Allen ◽  
...  
Keyword(s):  
Metabolic Rate ◽  
Body Mass ◽  
Tursiops Truncatus ◽  
Energy Use ◽  
Bottlenose Dolphins ◽  
Resting Metabolic Rate ◽  
Respiratory Physiology ◽  
Terrestrial Mammals ◽  
Respiratory Flow ◽  
Sarasota Bay

We measured respiratory flow rates, and expired O 2 in 32 (2–34 years, body mass [ M b ] range: 73–291 kg) common bottlenose dolphins ( Tursiops truncatus ) during voluntary breaths on land or in water (between 2014 and 2017). The data were used to measure the resting O 2 consumption rate ( V ˙ O 2 , range: 0.76–9.45 ml O 2  min −1  kg −1 ) and tidal volume ( V T , range: 2.2–10.4 l) during rest. For adult dolphins, the resting V T , but not V ˙ O 2 , correlated with body mass ( M b , range: 141–291 kg) with an allometric mass-exponent of 0.41. These data suggest that the mass-specific V T of larger dolphins decreases considerably more than that of terrestrial mammals (mass-exponent: 1.03). The average resting s V ˙ O 2 was similar to previously published metabolic measurements from the same species. Our data indicate that the resting metabolic rate for a 150 kg dolphin would be 3.9 ml O 2  min −1  kg −1 , and the metabolic rate for active animals, assuming a multiplier of 3–6, would range from 11.7 to 23.4 ml O 2  min −1  kg −1 .\absbreak Our measurements provide novel data for resting energy use and respiratory physiology in wild cetaceans, which may have significant value for conservation efforts and for understanding the bioenergetic requirements of this species.

scholarly journals The Protection of Animals During Warfare

AJIL Unbound ◽  
2017 ◽  
Vol 111 ◽  
pp. 272-276
Author(s):  
Jérôme de Hemptinne
Keyword(s):  
Marine Mammals ◽  
Bottlenose Dolphins ◽  
Rapid Rate ◽  
Human Beings ◽  
Armed Groups ◽  
Military Operations ◽  
Protected Species ◽  
California Sea Lions ◽  
Animal Products ◽  
Sea Lions

In times of war, the first instinct is to relieve the suffering of human beings. Environmental and animal interests are always pushed into the background. However, warfare strongly affects natural resources, including animals, which makes animal issues a matter of great concern. Certain species have been vanishing at a rapid rate because of wars, often with disastrous effects on the food chain and on the ecological balance. Indeed, belligerents rarely take into account the adverse consequences of their military operations on animals. They even take advantage of the chaotic circumstances of war in order to poach protected species and to engage in the trafficking of expensive animal products. While generating billions of dollars each year, such poaching and trafficking allows armed groups to grow and to reinforce their authority over disputed territory. States have also trained, and continue to train, certain animals—principally marine mammals such as bottlenose dolphins and California sea lions—to perform military tasks, like ship and harbor protection, or mine detection and clearance. Millions of horses, mules, donkeys, camels, dogs, and birds are obliged to serve on various fronts (transport, logistics, or communications) and become particularly vulnerable targets.

scholarly journals Cetacean Research and Citizen Science in Kenya

2021 ◽  
Vol 8 ◽  
Author(s):  
Michael Gilbert Mwango’mbe ◽  
Jane Spilsbury ◽  
Steve Trott ◽  
Judith Nyunja ◽  
Nina Wambiji ◽  
...  
Keyword(s):  
Citizen Science ◽  
Marine Mammal ◽  
Marine Mammals ◽  
Bottlenose Dolphins ◽  
Conservation Strategies ◽  
Science Data ◽  
Pilot Whale ◽  
Area Of Interest ◽  
Mammal Conservation ◽  
Kenyan Coast

In 2011, several non-governmental and government agencies established the Kenya Marine Mammal Network (KMMN) to provide a platform for the consistent collection of data on marine mammals along the Kenyan coast, identify areas of importance and engage marine users and the general public in marine mammal conservation. Prior to the KMMN, relatively little was known about marine mammals in Kenya, limiting conservation strategies. The KMMN collects data nationwide through dedicated surveys, opportunistic sightings and participative citizen science, currently involving more than 100 contributors. This paper reviews data on sightings and strandings for small cetaceans in Kenya collated by the KMMN. From 2011 to 2019, 792 records of 11 species of small cetaceans were documented. The most frequently reported inshore species were the Indo-Pacific bottlenose dolphin and Indian Ocean humpback dolphin. Offshore species, included killer whales, short-finned pilot whale and long-snouted spinner dolphin. Indo-Pacific bottlenose dolphins, long-snouted spinner dolphins, striped dolphins and Risso’s dolphins were recorded through stranding reports. The efforts of the KMMN were disseminated through international meetings (International Whaling Commission, World Marine Mammal Conference), national status reports, outreach and social media. Data has also supported the identification of three IUCN Important Marine Mammal Areas and one Area of Interest in Kenya. Further research is needed to improve estimates of cetacean abundance and distribution, particularly in unstudied coastal areas, and to assess the extent of anthropogenic threats associated with fisheries, coastal and port development, seismic exercises and unregulated tourism. The expansion of the network should benefit from the participation of remote coastal fishing communities, government research agencies, tourism and seismic operations, among others. The KMMN demonstrated the value of dedicated and citizen science data to enhance marine mammal conservation strategies to boost awareness and eco-tourism and to bring the public and science closer together, promoting research and effective conservation efforts.

scholarly journals Spatial and temporal variation in the occurrence of bottlenose dolphins in the Chesapeake Bay, USA, using citizen science sighting data

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0251637
Author(s):  
Lauren Kelly Rodriguez ◽  
Amber D. Fandel ◽  
Benjamin R. Colbert ◽  
Jamie C. Testa ◽  
Helen Bailey
Keyword(s):  
Chesapeake Bay ◽  
Citizen Science ◽  
Marine Mammals ◽  
Generalized Additive Models ◽  
Bottlenose Dolphins ◽  
Temporal Distribution ◽  
Additive Models ◽  
Spatial And Temporal Variation ◽  
Estuarine System ◽  
Predictive Tool

Bottlenose dolphins (Tursiops truncatus) are migratory marine mammals that live in both open-ocean and coastal habitats. Although widely studied, little is known about their occurrence patterns in the highly urbanized estuary of the Chesapeake Bay, USA. The goal of this study was to establish the spatial and temporal distribution of bottlenose dolphins throughout this large estuarine system and use statistical modeling techniques to determine how their distribution relates to environmental factors. Three years (April-October 2017–2019) of dolphin sighting reports from a citizen-science database, Chesapeake DolphinWatch, were analyzed. The dolphins had a distinct temporal pattern, most commonly sighted during summer months, peaking in July. This pattern of observed occurrence was confirmed with systematic, passive acoustic detections of dolphin echolocation clicks from local hydrophones. Using spatially-exclusive Generalized Additive Models (GAM), dolphin presence was found to be significantly correlated to spring tidal phase, warm water temperature (24–30°C), and salinities ranging from 6–22 PPT. We were also able to use these GAMs to predict dolphin occurrence in the Bay. These predictions were statistically correlated to the actual number of dolphin sighting reported to Chesapeake DolphinWatch during that time. These models for dolphin presence can be implemented as a predictive tool for species occurrence and inform management of this protected species within the Chesapeake Bay.

scholarly journals Age determination of common bottlenose dolphins (Tursiops truncatus) using dental radiography pulp:tooth area ratio measurements

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242273
Author(s):  
Jean M. Herrman ◽  
Jeanine S. Morey ◽  
Ryan Takeshita ◽  
Sylvain De Guise ◽  
Randall S. Wells ◽  
...  
Keyword(s):  
Life Histories ◽  
Marine Mammals ◽  
Bottlenose Dolphins ◽  
Age Determination ◽  
Area Ratio ◽  
Dental Radiography ◽  
Ratio Method ◽  
Data Sets ◽  
Photo Identification ◽  
Development And Validation

Age is an important parameter to better understand wildlife populations, and is especially relevant for interpreting data for fecundity, health, and survival assessments. Estimating ages for marine mammals presents a particular challenge due to the environment they inhabit: accessibility is limited and, when temporarily restrained for assessment, the window of opportunity for data collection is relatively short. For wild dolphins, researchers have described a variety of age-determination techniques, but the gold-standard relies upon photo-identification to establish individual observational life histories from birth. However, there are few populations with such long-term data sets, therefore alternative techniques for age estimation are required for individual animals without a known birth period. While there are a variety of methods to estimate ages, each involves some combination of drawbacks, including a lack of precision across all ages, weeks-to-months of analysis time, logistical concerns for field applications, and/or novel techniques still in early development and validation. Here, we describe a non-invasive field technique to determine the age of small cetaceans using periapical dental radiography and subsequent measurement of pulp:tooth area ratios. The technique has been successfully applied for bottlenose dolphins briefly restrained during capture-release heath assessments in various locations in the Gulf of Mexico. Based on our comparisons of dental radiography data to life history ages, the pulp:tooth area ratio method can reliably provide same-day estimates for ages of dolphins up to about 10 years old.

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