High heart rates in hunting harbour porpoises

The impressive breath-hold capabilities of marine mammals are facilitated by both enhanced O 2 stores and reductions in the rate of O 2 consumption via peripheral vasoconstriction and bradycardia, called the dive response. Many studies have focused on the extreme role of the dive response in maximizing dive duration in marine mammals, but few have addressed how these adjustments may compromise the capability to hunt, digest and thermoregulate during routine dives. Here, we use DTAGs, which record heart rate together with foraging and movement behaviour, to investigate how O 2 management is balanced between the need to dive and forage in five wild harbour porpoises that hunt thousands of small prey daily during continuous shallow diving. Dive heart rates were moderate (median minimum 47–69 bpm) and relatively stable across dive types, dive duration (0.5–3.3 min) and activity. A moderate dive response, allowing for some perfusion of peripheral tissues, may be essential for fuelling the high field metabolic rates required to maintain body temperature and support digestion during diving in these small, continuously feeding cetaceans. Thus, despite having the capacity to prolong dives via a strong dive response, for these shallow-diving cetaceans, it appears to be more efficient to maintain circulation while diving: extreme heart rate gymnastics are for deep dives and emergencies, not everyday use.

Optimizing Deepwater Rig Operations With Advanced Remotely Operated Vehicle Technology

In order for capital-intensive deepwater prospects to remain at investment grade potential, it is important the industry achieve meaningful improvement in capital efficiency. Achieving this goal will require a multi-faceted strategy in which advanced new technology and digital transformation will play a determining role. This paper will address the optimization of rig operations through deployment of an advanced Remotely Operated Vehicle (ROV) system that leverages precision robotics and automation technologies; reducing total cost of ownership (TCO) through increased rig productivity, operational certainty and overall utilization. Current ROV technology faces several key limitations which contribute to both schedule and cost variation. These inefficiencies are a combination of human skill variance, ROV system limitations and reliability. Advanced ROV systems have been deployed on two deepwater rigs to demonstrate that machine vision and precision robotics technologies will radically improve the predictability and efficiency of operations. Comprehensive metrics addressing safety, budget impact, cost avoidance & reduction, inventory reduction & non price TCO have been developed to capture the efficiencies and identify the net improvement to drilling and completion operations and yield outcome-based performance. An overview of the key deficiencies and limitations of legacy ROV operations will be conveyed, focusing on; i) High dependency on ROV pilot subsea task skills, ii) Worksite efficiency and ROV availability, iii) Restricted tooling capabilities per dive, iv) Rental tooling logistics and cost, v) Equipment reliability at depth, vi) Inefficient tooling changes, and vii) Dive duration and lost time efficiency launch/recovery time. An overview of how the advanced ROV system resolves these issues will be explained. In addition, an explanation of the productivity metrics will be conveyed, supported with data from the active offshore projects. Key conclusions from the data identify that enhanced robotics will achieve the objectives of i) Reducing schedule and cost risks which improve total cost of ownership, ii) Enhancing capability and improved wellsite efficiency, and iii) Increasing subsea data. The performance issues of legacy ROV operations and associated project cost impact is currently not widely recognized by the offshore drilling community. The realized limitations of such ROV operations and lack of useful performance metrics to identify non-productive time will be explained. The progression in robotic design that drives a new era of subsea robotic efficiency will be conveyed with results from offshore operations, combined with robust metrics that enable significant operational value and cost savings to be attained.

Dive Performance and Aquatic Thermoregulation of the World’s Smallest Mammalian Diver, the American Water Shrew (Sorex palustris)

Allometry predicts that the 12–17 g American water shrew (Sorex palustris)—the world’s smallest mammalian diver—will have the highest diving metabolic rate (DMR) coupled with the lowest total body oxygen storage capacity, skeletal muscle buffering capacity, and glycolytic potential of any endothermic diver. Despite these constraints, the maximum dive time (23.7 sec) and calculated aerobic dive limit (cADL; 10.8–14.4 sec) of wild-caught water shrews match or exceed values predicted by allometry based on studies of larger-bodied divers. The mean voluntary dive time of water shrews in 3, 10, 20, and 30°C water was 5.1±0.1 sec (N=25, n=1584), with a mean maximum dive time of 10.3±0.4 sec. Only 2.3–3.9% of dives in 30 and 10°C water, respectively, exceeded the cADL. Mean dive duration, duration of the longest dive, and total time in water all decreased significantly as temperature declined, suggesting that shrews employed behavioural thermoregulation to defend against immersion hypothermia. As expected from their low thermal inertia, diving shrews had a significantly higher DMR in 10°C (8.77 mL O2 g-1 hr-1) compared to 30°C water (6.57 mL O2 g-1 hr-1). Diving behavior of radio-telemetered shrews exclusively foraging in a simulated riparian environment (3°C water) for 12- to 28-hours suggest that mean (but not maximum) dive times of water shrews in the wild may be longer than predicted from our voluntary dive trials, as the average dive duration (6.9±0.2 sec, n=257) was ∼1.75× longer than during 20-min trials with no access to food at the same water temperature. Notably, free-diving shrews in the 24-hr trials consistently elevated core body temperature by ∼1.0–1.5°C immediately prior to initiating aquatic foraging bouts, and ended these bouts when body temperature was still at or above normal resting levels (∼37.8°C). We suggest this observed pre-dive hyperthermia aids to heighten the impressive somatosensory physiology, and hence foraging efficiency, of this diminutive predator while submerged.

Short-term responses of sperm whales Physeter macrocephalus to the attachment of suction cup tags

Animal-mounted data logging devices are used to study the behaviour, physiology, and ecology of free-ranging marine mammals, as well as their reactions to controlled exposures. It is important to consider whether collected data are representative of natural behaviour or biased by responses to tagging. In species with stereotypical diving behaviour, tagging responses can be quantified by identifying anomalous dives. Data from 36 suction cup tag deployments on sperm whales Physeter macrocephalus from 4 locations were analysed to consider whether tagging effects were evident within 5 dive parameters: maximum dive depth, dive duration, descent speed, depth difference between start of clicking and first prey capture attempt, and buzz rate. Linear mixed models were generated for each response parameter and covariates for dive index were added to assess whether model fit improved when the order of dives was taken into account. Time-decaying tagging effects were noted in maximum dive depth (first dives were 25% shallower than average) and buzz rate (first dives contained 34% fewer buzzes per minute than average). In the Azores, the first 3 dives subsequent to tag attachment featured faster descent speeds than average. The whales were likely responding to the cumulative ‘dose’ of research activity at the surface: multiple boat approaches, tag placement, and general disturbance. Disturbance should be minimised during tagging, and the extent and duration of responses should be quantified. Modelling of quantified tagging responses could enable correction of these responses in tag data.

Universal metabolic constraints shape the evolutionary ecology of diving in animals

Diving as a lifestyle has evolved on multiple occasions when air-breathing terrestrial animals invaded the aquatic realm, and diving performance shapes the ecology and behaviour of all air-breathing aquatic taxa, from small insects to great whales. Using the largest dataset yet assembled, we show that maximum dive duration increases predictably with body mass in both ectotherms and endotherms. Compared to endotherms, ectotherms can remain submerged for longer, but the mass scaling relationship for dive duration is much steeper in endotherms than in ectotherms. These differences in diving allometry can be fully explained by inherent differences between the two groups in their metabolic rate and how metabolism scales with body mass and temperature. Therefore, we suggest that similar constraints on oxygen storage and usage have shaped the evolutionary ecology of diving in all air-breathing animals, irrespective of their evolutionary history and metabolic mode. The steeper scaling relationship between body mass and dive duration in endotherms not only helps explain why the largest extant vertebrate divers are endothermic rather than ectothermic, but also fits well with the emerging consensus that large extinct tetrapod divers (e.g. plesiosaurs, ichthyosaurs and mosasaurs) were endothermic.

Marine temperature and depth use by anadromous Arctic char correlates to body size and diel period

Acoustic and archival telemetry were used to study the marine movements of 115 anadromous Arctic char (Salvelinus alpinus) at two sites in southern Labrador, Canada, in relation to daily variation in temperature and depth use, body size, and their effects on marine activity patterns. Although evidence varied between locations, Arctic char generally utilized ambient water temperatures available in the upper water column, possibly in aid of physiological processes such as digestion, whereas deeper waters were suggested to be used for feeding purposes. Size-dependent thermal preferences were evident, with larger individuals utilizing cooler water temperatures (8.5 °C) compared with smaller individuals (9.5 °C), a pattern suggestive of ontogenetic changes in thermal habitat use for the purposes of growth maximization. Diurnal patterns of diving activity were interpreted to reflect the vertical migration of prey items and (or) the visual capabilities of Arctic char. Dive duration was dependent on body size and external body temperature with smaller individuals performing shorter dives in colder water temperatures (<1 min at 5 °C) than larger fish (∼2 min at 5 °C), likely to maintain their core temperature and abilities to both effectively capture prey and avoid predation.

Diving deep into trouble: the role of foraging strategy and morphology in adapting to a changing environment

Physiology places constraints on an animal’s ability to forage and those unable to adapt to changing conditions may face increased challenges to reproduce and survive. As the global marine environment continues to change, small, air-breathing, endothermic marine predators such as otariids (fur seals and sea lions) and particularly females, who are constrained by central place foraging during breeding, may experience increased difficulties in successfully obtaining adequate food resources. We explored whether physiological limits of female otariids may be innately related to body morphology (fur seals vs sea lions) and/or dictate foraging strategies (epipelagic vs mesopelagic or benthic). We conducted a systematic review of the increased body of literature since the original reviews of Costa et al. (When does physiology limit the foraging behaviour of freely diving mammals? Int Congr Ser 2004;1275:359–366) and Arnould and Costa (Sea lions in drag, fur seals incognito: insights from the otariid deviants. In Sea Lions of the World Fairbanks. Alaska Sea Grant College Program, Alaska, USA, pp. 309–324, 2006) on behavioural (dive duration and depth) and physiological (total body oxygen stores and diving metabolic rates) parameters. We estimated calculated aerobic dive limit (cADL—estimated duration of aerobic dives) for species and used simulations to predict the proportion of dives that exceeded the cADL. We tested whether body morphology or foraging strategy was the primary predictor of these behavioural and physiological characteristics. We found that the foraging strategy compared to morphology was a better predictor of most parameters, including whether a species was more likely to exceed their cADL during a dive and the ratio of dive time to cADL. This suggests that benthic and mesopelagic divers are more likely to be foraging at their physiological capacity. For species operating near their physiological capacity (regularly exceeding their cADL), the ability to switch strategies is limited as the cost of foraging deeper and longer is disproportionally high, unless it is accompanied by physiological adaptations. It is proposed that some otariids may not have the ability to switch foraging strategies and so be unable adapt to a changing oceanic ecosystem.

HUBUNGAN ANTARA PENGETAHUAN MENYELAM DENGAN GANGGUAN PENDENGARAN PADA PEKERJA BAWAH AIR DI PERUSAHAAN KONSTRUKSI BAWAH LAUT

Underwater workers were prone to hearing loss. Pressure during diving and depth of dive were causing hearing loss.Jobs that are at risk for barotrauma are divers, keepers or pearl takers, marine boat keepers, rescue teams, and underwater construction work. Diving which requires a longer dive duration and deeper depth is very susceptible to health problems such as damage to the lungs, brain hemorrhage, gas poisoning and loss of body heat. This study aims to learn relationship between dive knowledge and hearing loss. The design of this research is a cross sectional study. This research is a descriptive research, because this research is the whole population. This was observational study carried out from April until June 2017 used cross sectional method. The dependent variable in this study is hearing loss, while the independent variable is diving knowledge. The result showed that obtained from 6 respondents, 100% of the respondents with bad knowledge suffer from moderate hearing loss, 60% of the respondents with sufficient knowledge suffer from mild hearing loss and 40% of the respondents with sufficient knowledge do not suffer from hearing loss. Contingency coefficient statistical test results indicate that there is a relationship between diving knowledge and hearing loss in PT Aquamarine Divindo Inspection Sidoarjo. The better knowledge can affect the respondent’s hearing loss. The conclusion in this study is the Ambang Listen Value using the audiometry test most respondents are mild deaf.Keywords: audiometric, hearing loss, underwater construction, underwater workers

The extra burden of motherhood: reduced dive duration associated with pregnancy status in a deep-diving mammal, the northern elephant seal

The cost of pregnancy is hard to study in marine mammals, particularly in species that undergo pregnancy while diving continuously at sea such as elephant seals (genus Mirounga ). We analysed the diving behaviour of confirmed pregnant and non-pregnant northern elephant seals ( M. angustirostris , n = 172) and showed that after an initial continuous increase in dive duration, dives of pregnant females become shorter after week 17. The reasons for this reduction in dive duration remain unknown, but we hypothesize that increased fetal demand for oxygen could be the cause. Our findings reveal an opportunity to explore the use of biologging data to investigate pregnancy status of free-ranging marine mammals and factors that could affect pregnancy success.

Horizontal and vertical movements of white marlin, Kajikia albida, tagged off the Yucatán Peninsula

The white marlin, Kajikia albida, is a highly migratory, prized sport fish of conservation concern. Improved understanding of white marlin ecology, including habitat use, will inform management measures. To improve white marlin movement knowledge in a region with limited information, we tagged 18 individuals off the eastern Yucatan Peninsula, Mexico with pop-up satellite archival transmitters. Tracks lasting 9–328 d, yielded data across 1277 d, and covered distances of 891–10 579 km. Horizontal movements varied greatly with ten individuals remaining in the Gulf of Mexico/northwestern Caribbean and eight individuals entering the western North Atlantic. Although white marlin experienced a temperature range of 10.0–33.6 °C, the majority of time was spent in waters &gt;24 °C. Marlin displayed diel diving patterns with deeper dives occurring more frequently during the daytime. As water columns warmed, dive duration, maximum daily depth, and dive depth all increased. As a result, 18% of the time was spent at depths &gt;100 m in the warmest water columns compared with &lt;1% in the coldest water columns. Although the thermal characteristics of the water column greatly influence white marlin diving behaviour, the generally shallow distributions provide a way of separating white marlin from important fishery species.