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"Deep diving."
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Deep-diving submarines
Introduces readers to the different parts of a submarine and explains how these vehicles move through the water.
Book
Long‐Term Depth Records of Satellite‐Tagged Northern Bottlenose Whales Reveal Extraordinary Dive Capabilities
Studying the baseline behavior of deep‐diving mammals can substantially improve our understanding of these species' ecology and provide important benchmarks to evaluate effects of changes in climate and anthropogenic activities. Despite being the most abundant beaked whale in the Arctic and subarctic, information on the behavior of northern bottlenose whales (Hyperoodon ampullatus) is limited. This study used records from 13 satellite tags deployed off Jan Mayen in June–July 2014–2016 to provide an extensive description of the dive behavior of Hyperoodon for the Nordic Seas. A total of 8372 dives, collected over 224 days (or 5376 h), were analyzed. The whales performed extreme dives of up to 2288 m deep and 98 min long—deeper and longer than previously reported for behavior in presumed undisturbed contexts. Individuals spent on average 18% of the time at depths shallower than 40 m, and 22%, 47%, and 12% in epi‐, meso‐, and bathypelagic dives, respectively. Epipelagic dives averaged 123 m (s.d.: 46 m) in depth and 11 min (5 min) in duration. Mesopelagic dives averaged 441 m (217 m) and 24 min (11 min) and were performed at a mean rate of 1.46 h−1. Bathypelagic dives averaged 1487 m (366 m) and 55 min (13 min) and were performed at a mean rate of 0.23 h−1. The distribution of dive depths was less bimodal than typically reported for other beaked whales, and all dive profiles contained periods of continuous, consecutive deep dives. Benthic diving occurred at meso‐ and especially bathypelagic depths and was individual specific, varying from 8% to 51% of the animal's bathypelagic dives. Overall, our findings demonstrate that northern bottlenose whales have extraordinary capabilities to dive, and presumably feed, throughout the water column including at the sea floor. High rates of deep dives highlight the importance of the Iceland and Norwegian Seas to this population of deep‐sea predators. This study used records from 13 satellite tags deployed off Jan Mayen to provide an extensive description of the dive behavior of northern bottlenose whales in the Nordic Seas. Our findings demonstrate that this species has extraordinary capabilities to dive, and presumably feed, throughout the water column including at the sea floor. High rates of deep dives highlight the importance of the Iceland and Norwegian Seas habitat to this population of deep‐sea predators.
Journal Article
Unravelling the mysteries of a mesopelagic diet: a large apex predator specializes on small prey
1. To gain insight into the foraging behaviour of deep diving seals, we developed a long-term jaw-motion recorder, which successfully measured the feeding attempts of four post-breeding female northern elephant seals for 55—68 days during migration in the north-east Pacific Ocean. 2. Using the jaw-motion recorders in conjunction with satellite tracking data, we first reveal the three-dimensional fine-scale distribution of deep foraging activity in the north-east Pacific Ocean. 3. A large number of jaw-motion events (23817—58766 during 2925—4178 dives, per seal) were observed with diel patterns suggesting their dependency on small mesopelagic prey. Calculations using at-sea field metabolic-rate and the photographs concurrently obtained by the head-mounted camera indicated feeding on small mesopelagic prey (10—20 g) including lantern fish (F. Myctophidae). 4. The foraging behaviour of the northern elephant seal contrasts with echolocating toothed whales, which make fewer feeding attempts, suggesting the whales forage more selectively. We hypothesize that the continuous diving mode exhibited by this seal could be attributed to their reliance on small prey and their less efficient 'passive sensors' for prey search, that is, their vision or whiskers to detect prey.
Journal Article
Exploring under the sea
This title covers deep sea exploration, from ancient attempts to modern exploration using advanced technology.
Book
Into the deep: the functionality of mesopelagic excursions by an oceanic apex predator
Comprehension of ecological processes in marine animals requires information regarding dynamic vertical habitat use. While many pelagic predators primarily associate with epipelagic waters, some species routinely dive beyond the deep scattering layer. Actuation for exploiting these aphotic habitats remains largely unknown. Recent telemetry data from oceanic whitetip sharks (Carcharhinus longimanus) in the Atlantic show a strong association with warm waters (>20°C) less than 200 m. Yet, individuals regularly exhibit excursions into the meso‐ and bathypelagic zone. In order to examine deep‐diving behavior in oceanic whitetip sharks, we physically recovered 16 pop‐up satellite archival tags and analyzed the high‐resolution depth and temperature data. Diving behavior was evaluated in the context of plausible functional behavior hypotheses including interactive behaviors, energy conservation, thermoregulation, navigation, and foraging. Mesopelagic excursions (n = 610) occurred throughout the entire migratory circuit in all individuals, with no indication of site specificity. Six depth‐versus‐time descent and ascent profiles were identified. Descent profile shapes showed little association with examined environmental variables. Contrastingly, ascent profile shapes were related to environmental factors and appear to represent unique behavioral responses to abiotic conditions present at the dive apex. However, environmental conditions may not be the sole factors influencing ascents, as ascent mode may be linked to intentional behaviors. While dive functionality remains unconfirmed, our study suggests that mesopelagic excursions relate to active foraging behavior or navigation. Dive timing, prey constituents, and dive shape support foraging as the most viable hypothesis for mesopelagic excursions, indicating that the oceanic whitetip shark may regularly survey extreme environments (deep depths, low temperatures) as a foraging strategy. At the apex of these deep‐water excursions, sharks exhibit a variable behavioral response, perhaps, indicating the presence or absence of prey. Although often regarded as the consummate predator, sharks face a life‐long challenge to locate and capture prey. Using a theoretical approach and the most current biotelemetry instruments, we show that even the oceans' apex predators regularly survey extreme environments (deep depths, low temperatures) as a foraging strategy. At the apex of these deep‐water excursions, sharks exhibit a variable behavioral response for the return to more hospitable surface waters, perhaps, indicating the presence or absence of prey.
Journal Article
The open ocean
\"More than 50 shells and sea creatures are hiding in this gorgeous life-the-flap book. Can you name them all?\"--Page 4 of cover.
Book
Individual, ecological, and anthropogenic influences on activity budgets of long‐finned pilot whales
Time allocation to different activities and habitats enables individuals to modulate their perceived risks and access to resources and can reveal important trade‐offs between fitness‐enhancing activities (e.g., feeding vs. social behavior). Species with long reproductive cycles and high parental investment, such as marine mammals, rely on such behavioral plasticity to cope with rapid environmental change, including anthropogenic stressors. We quantified activity budgets of free‐ranging long‐finned pilot whales in order to assess individual time trade‐offs between foraging and other behaviors in different individual and ecological contexts, and during experimental sound exposures. The experiments included 1–2 and 6–7 kHz naval sonar exposures (a potential anthropogenic stressor), playback of killer whale (a potential predator/competitor) vocalizations, and negative controls. We combined multiple time series data from digital acoustic recording tags (DTAG) as well as group‐level social behavior data from visual observations of tagged whales at the surface. The data were classified into near‐surface behaviors and dive types (using a hidden Markov model for dive transitions) and aggregated into time budgets. On average, individuals (N = 19) spent most of their time (69%) resting and transiting near surface, 21% in shallow dives (depth <40 m), and only 10% of their time in deep foraging dives, of which 65% reached a depth 10 m from the sea bottom. Individuals in the largest of three body size classes or accompanied by calves tended to spend more time foraging than others. Simultaneous tagging of pairs of individuals showed that up to 50% of the activity budget was synchronized between conspecifics with decreased synchrony during foraging periods. Individuals spent less time foraging when forming larger non‐vocal aggregations of individuals in late afternoons, and more time foraging when in the mid‐range of water depths (300–400 m) available in the study area (50–700 m). Individuals reduced foraging time by 83% (29–96%) during their first exposure to sonar, but not during killer whale sound playbacks. A relative increase in foraging during repeat sonar exposures indicated habituation or change in response tactic. We discuss the possible adaptive value of these trade‐offs in time allocation to reduce individual conflict while maintaining benefits of group living.
Journal Article
Diving with sharks! : and more true stories of extreme adventures!
Shares true stories of cave divers, extreme photographers, and researchers as they brave undersea adventures with sharks.
Book
Deep Diving underwater works in Poland
In the article the author describes the Polish specificity of deep dives used in underwater deep-sea works. The article briefly discusses the methods of deep diving used in the world to proceed to underwater works in the Polish offshore zone of 50-90m depth (according to the Act; deep water works are works below a depth of 50m). When discussing these methods, the author describes the technical-organisational and formal conditions and the type of conducted works. It then presents the methodology for evaluating the effectiveness of the main element of deep-sea works, i.e. diving. It provides information on deepsea underwater works on the Baltic Sea carried out by the Department of Underwater Works Technology of the Naval Academy in cooperation with the Polish Navy until 2001 and civil companies to date. On the basis of his own data from underwater deep-sea works, the author presents the methodology of evaluation of their effectiveness from the point of view of deep dives. In his conclusions, he puts forward recommendations for improving the efficiency of such works.
Journal Article