Battery/Ultracapacitor Evaluation for X-38 Crew Return Vehicle (CRV)

This presentation reported on the evaluation of the battery/ultracapacitor for the crew return vehicle (CRV). The CRV, as part of the international space station (ISS) planning, will be available to return to earth an ill or injured crew person, or if the ISS becomes unsafe, and the shuttle is not available. The requirements of the X-38 CRV are reviewed, and in light of the power requirements, the battery's required performance is reviewed. The ultracapacitor bank, and its test method is described. The test results are reviewed. A picture of the test set up is displayed showing the ultracapacitor bank and the NiMH battery. The presentation continues by reviewing tests of 5 available trade high power cell designs: (1) Hawker lead acid, (2) Bolder lead acid, (3) Energizer NiMH, (4) Sanyo NiCd, and (5) Energizer NiCd. The test methods and results are reviewed. There is also a review of the issues concerning lead acid batteries and conclusions

Performance of High Voltage Modules Under Abuse Operations

The Electric Auxiliary Power Unit (EAPU) or the Advanced Hydraulic Power System (AHPS) is a Shuttle Upgrade program. Of the two battery design approaches that were considered in support of this program, the current paper concentrates on the testing performed on the small-cell approach. Testing performed at both ComDev Space, Canada and at NASA-JSC is described in this paper. Testing included those under mission profile conditions and off-nominal abusive conditions

Observations of forest birds at Ol Donyo Sabuk National Park, Machakos County, Kenya

A previous report recorded 19 species of forest-dependent birds in Ol Donyo Sabuk National Park. Using field surveys, literature review, and database records, we add an additional 17 forest-dependent bird species bringing the total number to 36.Keywords: Ol Donyo Sabuk, forest-dependent birds, conservation, distributio

Leveraging satellite technology to create true shark sanctuaries

Shark sanctuaries are an ambitious attempt to protect huge areas of ocean space to curtail overfishing of sharks. If shark sanctuaries are to succeed, effective surveillance and enforcement is urgently needed. We use a case study with a high level of illegal shark fishing within a shark sanctuary to help motivate three actionable opportunities to create truly effective shark sanctuaries by leveraging satellite technology: (1) require vessel tracking systems; (2) partner with international research organizations; and (3) ban vessels previously associated with illegal fishing from shark sanctuaries. Sustaining the level of fishing mortality observed in our case study would lead even a healthy shark population to collapse to <10% of its unfished state in fewer than five years. We outline implementations pathways and provide a roadmap to pair new and emerging satellite technologies with existing international agreements to offer new hope for shark conservation successes globally

Drivers of Daily Routines in an Ectothermic Marine Predator: Hunt Warm, Rest Warmer?

Animal daily routines represent a compromise between maximizing foraging success and optimizing physiological performance, while minimizing the risk of predation. For ectothermic predators, ambient temperature may also influence daily routines through its effects on physiological performance. Temperatures can fluctuate significantly over the diel cycle and ectotherms may synchronize behaviour tomatch thermal regimes in order to optimize fitness. We used bio-logging to quantify activity and body temperature of blacktip reef sharks (Carcharhinus melanopterus) at a tropical atoll. Behavioural observations were used to concurrently measure bite rates in herbivorous reef fishes, as an index of activity for potential diurnal prey. Sharks showed early evening peaks in activity, particularly during ebbing high tides, while body temperatures peaked several hours prior to the period of maximal activity. Herbivores also displayed peaks in activity several hours earlier than the peaks in shark activity. Sharks appeared to be least active while their body temperatures were highest and most active while temperatures were cooling, although we hypothesize that due to thermal inertia they were still warmer than their smaller prey during this period. Sharksmay be most active during early evening periods as they have a sensory advantage under low light conditions and/ or a thermal advantage over cooler prey. Sharks swaminto shallow water during daytime low tide periods potentially to warm up and increase rates of digestion before the nocturnal activity period, which may be a strategy to maximize ingestion rates. Hunt warm, rest warmer may help explain the early evening activity seen in other ectothermic predators

Growth and life history variability of the grey reef shark (Carcharhinus amblyrhynchos) across its range

For broadly distributed, often overexploited species such as elasmobranchs (sharks and rays), conservation management would benefit from understanding how life history traits change in response to local environmental and ecological factors. However, fishing obfuscates this objective by causing complex and often mixed effects on the life histories of target species. Disentangling the many drivers of life history variability requires knowledge of elasmobranch populations in the absence of fishing, which is rarely available. Here, we describe the growth, maximum size, sex ratios, size at maturity, and offer a direct estimate of survival of an unfished population of grey reef sharks (Carcharhinus amblyrhynchos) using data from an eight year tag-recapture study. We then synthesized published information on the life history of C. amblyrhynchos from across its geographic range, and for the first time, we attempted to disentangle the contribution of fishing from geographic variation in an elasmobranch species. For Palmyra’s unfished C. amblyrhynchos population, the von Bertalanffy growth function (VBGF) growth coefficient k was 0.05 and asymptotic length L∞ was 163.3 cm total length (TL). Maximum size was 175.5 cm TL from a female shark, length at maturity was estimated at 116.7–123.2 cm TL for male sharks, maximum lifespan estimated from VBGF parameters was 18.1 years for both sexes combined, and annual survival was 0.74 year-1. Consistent with findings from studies on other elasmobranch species, we found significant intraspecific variability in reported life history traits of C. amblyrhynchos. However, contrary to what others have reported, we did not find consistent patterns in life history variability as a function of biogeography or fishing. Ultimately, the substantial, but not yet predictable variability in life history traits observed for C. amblyrhynchos across its geographic range suggests that regional management may be necessary to set sustainable harvest targets and to recover this and other shark species globally

Resetting predator baselines in coral reef ecosystems

What did coral reef ecosystems look like before human impacts became pervasive? Early efforts to reconstruct baselines resulted in the controversial suggestion that pristine coral reefs have inverted trophic pyramids, with disproportionally large top predator biomass. The validity of the coral reef inverted trophic pyramid has been questioned, but until now, was not resolved empirically. We use data from an eight-year tag-recapture program with spatially explicit, capture-recapture models to re-examine the population size and density of a key top predator at Palmyra atoll, the same location that inspired the idea of inverted trophic biomass pyramids in coral reef ecosystems. Given that animal movement is suspected to have significantly biased early biomass estimates of highly mobile top predators, we focused our reassessment on the most mobile and most abundant predator at Palmyra, the grey reef shark (Carcharhinus amblyrhynchos). We estimated a density of 21.3 (95% CI 17.8, 24.7) grey reef sharks/km2, which is an order of magnitude lower than the estimates that suggested an inverted trophic pyramid. Our results indicate that the trophic structure of an unexploited reef fish community is not inverted, and that even healthy top predator populations may be considerably smaller, and more precarious, than previously thought

Activity seascapes highlight central place foraging strategies in marine predators that never stop swimming

Background: Central place foragers (CPF) rest within a central place, and theory predicts that distance of patches from this central place sets the outer limits of the foraging arena. Many marine ectothermic predators behave like CPF animals, but never stop swimming, suggesting that predators will incur ‘travelling’ costs while resting. Currently, it is unknown how these CPF predators behave or how modulation of behavior contributes to daily energy budgets. We combine acoustic telemetry, multi-sensor loggers, and hidden Markov models (HMMs) to generate ‘activity seascapes’, which combine space use with patterns of activity, for reef sharks (blacktip reef and grey reef sharks) at an unfished Pacific atoll. Results: Sharks of both species occupied a central place during the day within deeper, cooler water where they were less active, and became more active over a larger area at night in shallower water. However, video cameras on two grey reef sharks revealed foraging attempts/success occurring throughout the day, and that multiple sharks were refuging in common areas. A simple bioenergetics model for grey reef sharks predicted that diel changes in energy expenditure are primarily driven by changes in swim speed and not body temperature. Conclusions: We provide a new method for simultaneously visualizing diel space use and behavior in marine predators, which does not require the simultaneous measure of both from each animal. We show that blacktip and grey reef sharks behave as CPFs, with diel changes in activity, horizontal and vertical space use. However, aspects of their foraging behavior may differ from other predictions of traditional CPF models. In particular, for species that never stop swimming, patch foraging times may be unrelated to patch travel distance

Atmospheric CO2 emissions and ocean acidification from bottom-trawling

Trawling the seafloor can disturb carbon that took millennia to accumulate, but the fate of that carbon and its impact on climate and ecosystems remains unknown. Using satellite-inferred fishing events and carbon cycle models, we find that 55-60% of trawling-induced aqueous CO2 is released to the atmosphere over 7-9 years. Using recent estimates of bottom trawling’s impact on sedimentary carbon, we found that between 1996-2020 trawling could have released, at the global scale, up to 0.34-0.37 Pg CO2 yr-1 to the atmosphere, and locally altered water pH in some semi-enclosed and heavy trawled seas. Our results suggest that the management of bottom-trawling efforts could be an important climate solution

Dermal denticle assemblages in coral reef sediments correlate with conventional shark surveys

Abstract It is challenging to assess long‐term trends in mobile, long‐lived and relatively rare species such as sharks. Despite ongoing declines in many coastal shark populations, conventional surveys might be too fleeting and too recent to describe population trends over decades to millennia. Placing recent shark declines into historical context should improve management efforts as well as our understanding of past ecosystem dynamics. A new palaeoecological approach for surveying shark abundance on coral reefs is to quantify dermal denticle assemblages preserved in sediments. This approach assumes that denticle accumulation rates correlate with shark abundances. Here, we test this assumption by comparing the denticle record in surface sediments to three conventional shark survey methods at Palmyra Atoll, Line Islands, central Pacific Ocean, where shark density is high and spatially heterogeneous. We generally found a significant positive correlation between denticle accumulation rates and shark abundances derived from underwater visual census, baited remote underwater video and hook and line surveys. Denticle accumulation rates reflected shark abundances, suggesting that denticle assemblages can preserve a signal of time‐averaged shark abundance in low‐energy coral reef environments. We offer suggestions for applying this tool to measure shark abundance over long time‐scales in other contexts