‘‘Beet-ing’’ the Mountain: A Review of the Physiological and Performance Effects of Dietary Nitrate Supplementation at Simulated and Terrestrial Altitude

Exposure to altitude results in multiple physiological consequences. These include, but are not limited to, a reduced maximal oxygen consumption, drop in arterial oxygen saturation, and increase in muscle metabolic perturbations at a fixed sub-maximal work rate. Exercise capacity during fixed work rate or incremental exercise and time-trial performance are also impaired at altitude relative to sea-level. Recently, dietary nitrate (NO3-) supplementation has attracted considerable interest as a nutritional aid during altitude exposure. In this review, we summarise and critically evaluate the physiological and performance effects of dietary NO3- supplementation during exposure to simulated and terrestrial altitude. Previous investigations at simulated altitude indicate that NO3- supplementation may reduce the oxygen cost of exercise, elevate arterial and tissue oxygen saturation, improve muscle metabolic function, and enhance exercise capacity/ performance. Conversely, current evidence suggests that NO3- supplementation does not augment the training response at simulated altitude. Few studies have evaluated the effects of NO3- at terrestrial altitude. Current evidence indicates potential improvements in endothelial function at terrestrial altitude following NO3- supplementation. No effects of NO3- supplementation have been observed on oxygen consumption or arterial oxygen saturation at terrestrial altitude, although further research is warranted. Limitations of the present body of literature are discussed, and directions for future research are provided

The behaviour of giant clams (Bivalvia: Cardiidae: Tridacninae)

Giant clams, the largest living bivalves, live in close association with coral reefs throughout the Indo-Pacific. These iconic invertebrates perform numerous important ecological roles as well as serve as flagship species—drawing attention to the ongoing destruction of coral reefs and their associated biodiversity. To date, no review of giant clams has focussed on their behaviour, yet this component of their autecology is critical to their life history and hence conservation. Almost 100 articles published between 1865 and 2014 include behavioural observations, and these have been collated and synthesised into five sections: spawning, locomotion, feeding, anti-predation, and stress responses. Even though the exact cues for spawning in the wild have yet to be elucidated, giant clams appear to display diel and lunar periodicities in reproduction, and for some species, peak breeding seasons have been established. Perhaps surprisingly, giant clams have considerable mobility, ranging from swimming and gliding as larvae to crawling in juveniles and adults. Chemotaxis and geotaxis have been established, but giant clams are not phototactic. At least one species exhibits clumping behaviour, which may enhance physical stabilisation, facilitate reproduction, or provide protection from predators. Giant clams undergo several shifts in their mode of acquiring nutrition; starting with a lecithotrophic and planktotrophic diet as larvae, switching to pedal feeding after metamorphosis followed by the transition to a dual mode of filter feeding and phototrophy once symbiosis with zooxanthellae (Symbiodinium spp.) is established. Because of their shell weight and/or byssal attachment, adult giant clams are unable to escape rapidly from threats using locomotion. Instead, they exhibit a suite of visually mediated anti-predation behaviours that include sudden contraction of the mantle, valve adduction, and squirting of water. Knowledge on the behaviour of giant clams will benefit conservation and restocking efforts and help fine-tune mariculture techniques. Understanding the repertoire of giant clam behaviours will also facilitate the prediction of threshold levels for sustainable exploitation as well as recovery rates of depleted clam populations

OBSERVATIONS ON REMOVAL OF SPINES BY MURICID GASTROPODS DURING SHELL GROWTH

Volume: 15Start Page: 69End Page: 7

Variability, developmental changes, and denticle-replacement in the radula of Lymnaea stagnalis appressa Say

Volume: 57Start Page: 52End Page: 5

Prismatic Shell Formation in Continuously Isolated (Mytilus edulis) and Periodically Exposed (Crassostrea virginica) Extrapallial Spaces - Explicable by the Same Concept

Volume: 9Start Page: 193End Page: 19

Predatory Gastropod Traces: a Comparison of Verified Shallow water and Presumed Deep sea Boreholes

Volume: 14Start Page: 121End Page: 13

Northern quahog (Mercenaria mercenaria) larval transport and settlement modeled for a temperate estuary

Evaluating marine species\u27 population connectivity through larval transport can provide insight into the reliance of geographically separated areas on each other\u27s recruitment and metapopulation resiliency. Using larval transport modeling, we assessed the significance of different regions in supporting the Narragansett Bay Northern quahog (Mercenaria mercenaria) population. We aimed to identify how areas with varying adult quahog biomass and implemented management strategies (based on water quality and commercial harvest) contribute to the overall stock\u27s larval supply. Larval trajectories were modeled by integrating the currents from a realistic physical circulation model with quahog larval behavior applied to particles during spawning periods of 2006, 2007, and 2014. Modeled larval transport suggested that settlement occurs throughout Narragansett Bay, with 35% of spawned larvae swept out of the Bay to the coastal ocean and leaving the stock bounds. Quahogs in areas where shellfishing is prohibited due to water quality concerns produce a significant portion of the Bay\u27s spawned larvae, theoretically serving as de facto spawning sanctuaries. The Providence River, located at the head of the Bay with high mature quahog biomass and currently closed to fishing due to water quality, is a significant source of quahog larvae for the stock. Simulated larval quahog settlement locations corresponded predominantly to sandy bottoms, with less spatial correspondence to commercial fisheries landings. Our work provides insight into the population connectivity of quahogs in Narragansett Bay and highlights the importance of considering oceanography and species\u27 life history characteristics when constructing effective fisheries management plans