John Davenport

Temperature and the life-history strategies of sea turtles

Abstract 1. 1. Sea turtles have a high fecundity, high mortality, great longevity life history strategy. 2. 2. With the exception of the leatherback, turtle distribution is constrained by the 20°C surface isotherm. 3. 3. All sea turtles exhibit temperature-dependent sex determination (TSD) with pivotal temperatures close to 29°C. 4. 4. It is suggested that hatchling sex ratio will vary chaotically because of TSD. 5. 5. Because of TSD and natal homing, sea turtles are likely to be adversely affected by global warming. 6. 6. TSD and global warming have implications for conservation/management of sea turtles.

The ecology of transportation : managing mobility for the environment

This book describes how human transport by land, sea and air has dramatically increased over time. The book also describes how transport has paralleled a rise in population, prosperity and increased the rate at which technology is changing. Transport has considerable ecological effects, many of them are considered to be detrimental to the environmental sustainability. This volume brings together international experts from a variety of disciplines in order to review the ecological effects and their causes in terms of road, rail, ship, and aircraft transport. The contributors have different attitudes and agendas. Some are ecologists, some are planners, and others are social scientists. Focus ranges from identification of threats and amelioration of damaging effects through to the future design of transport systems in order to minimize environmental degradation. Some chapters consider restricted areas of the globe; others the globe itself. The views expressed encompass deep pessimism and cautious optimism. Uniquely, the book considers transport effects in all environments, and this is the first book that attempts to discuss the relationship between human transport and all ecosystems. It appeals not only to the specialist environmentalist by picking out novel topics, but also to anyone involved in transport issues as it tackles the issues from a historical perspective that encompasses the past, present and future of the effects of human transport.

A study of the effects of copper applied continuously and discontinuously to specimens of Mytilus edulis (L.) exposed to steady and fluctuating salinity levels

The study reported here stems from experiments performed upon cirripedes and bivalve molluscs exposed to fluctuating sea water concentrations. It is obvious that these two groups of benthic organisms are capable of shutting themselves off to a greater or lesser degree from the external environment by opercular or shell valve closure, thus avoiding the osmotic stresses associated with exposure to lowered salinity levels. With the development by Davenport, Gruffydd & Beaumont (1975) of an apparatus to deliver fluctuating salinity regimes to experimental animals in a repeatable, routine manner, it has become possible to establish the sea-water concentrations at which such mechanisms operate.

Ingestion of mesozooplankton by three species of bivalve; Mytilus edulis, Cerastoderma edule and Aequipecten opercularis

Mytilus edulis, Cerastoderma edule and Aequipecten opercularis were found to ingest zooplankton when susp- ended in mesh cages in the water column in the Firth of Clyde. Zooplankters were also found in the stomachs of bivalves that had been taken directly from their natural habitat. The bivalves consumed a wide range of zooplankton species, but selectively consumed smaller categories of zooplankton present. Condition of zooplankton in the stomachs of the bivalves varied with zooplankton species. A degree of larviphagy was evident, particularly in Mytilus edulis.

The broad-scale distribution of five jellyfish species across a temperate coastal environment

Jellyfish (medusae) are sometimes the most noticeable and abundant members of coastal planktonic communities, yet ironically, this high conspicuousness is not reflected in our overall understanding of their spatial distributions across large expanses of water. Here, we set out to elucidate the spatial (and temporal) patterns for five jellyfish species (Phylum Cnidaria, Orders Rhizostomeae and Semaeostomeae) across the Irish & Celtic Seas, an extensive shelf-sea area at Europe’s northwesterly margin encompassing several thousand square kilometers. Data were gathered using two independent methods: (1) surface-counts of jellyfish from ships of opportunity, and (2) regular shoreline surveys for stranding events over three consecutive years. Jellyfish species displayed distinct species-specific distributions, with an apparent segregation of some species. Furthermore, a different species composition was noticeable between the northern and southern parts of the study area. Most importantly, our data suggests that jellyfish distributions broadly reflect the major hydrographic regimes (and associated physical discontinuities) of the study area, with mixed water masses possibly acting as a trophic barrier or non-favourable environment for the successful growth and reproduction of jellyfish species.

Animal life at low temperature

One Introductory Material.- 1 Basic concepts.- 1.1 Temperature.- 1.2 Water and low temperature.- 1.3 Colligative properties of aqueous solutions.- 1.4 Categories of body temperature control.- 1.5 Zone of neutrality, critical temperatures.- 1.6 Newtons Law of cooling.- 1.7 Thermal conductance.- 1.8 Windchill.- 1.9 Q10 relationship.- 1.10 Cold acclimation and cold adaptation.- 1.11 Heat production.- 2 The cold environment.- 2.1 Present conditions.- 2.2 Palaeoclimatology.- 2.3 Climatic zones.- 2.4 High latitude microhabitats.- Two Behaviour, Anatomy and Physiology.- 3 Behavioural responses to low temperature.- 3.1 Movement.- 3.2 Basking.- 3.3 Gregariousness.- 3.4 Shelter.- 4 Anatomy and physiology of endotherms.- 4.1 Shape, size and climate.- 4.2 Structural insulation: fur, fat and feathers.- 4.3 Vascular arrangements to minimize heat loss.- 4.4 Physiological insulation.- 4.5 Thermogenesis.- 5 Sleep, torpor and hibernation.- 5.1 Sleep.- 5.2 Torpor and hibernation in ectotherms.- 5.3 Torpor in endotherms.- 5.4 Hibernation in endotherms.- 5.5 Supercooled hibernation in endotherms.- 5.6 Hibernation in bears.- Three Life at Temperatures Below 0 C.- 6 Subzero survival in terrestrial animals.- 6.1 Survival of insects and other terrestrial arthropods.- 6.2 Freezing-tolerance in terrestrial vertebrates.- 7 Subzero temperatures and marine ectotherms.- 7.1 Introduction.- 7.2 Supercooling in deep-water fish.- 7.3 Heightened plasma osmolarity in cold-water fish.- 7.4 Antifreezes in high latitude fish.- 7.5 Eggs of the capelin.- 7.6 Freezing in intertidal invertebrates.- 7.7 Freezing avoidance by intertidal invertebrates.- Four Man and Cold.- 8 Man and cold.- 8.1 Introduction.- 8.2 Human morphology and cold.- 8.3 Physiological/metabolic adaptations and responses.- 8.4 Damage by cold.- 8.5 Clothing.- 8.6 Shelter.- 8.7 Fire.- 8.8 Cold and human diet.- 8.9 Medical hypothermia.- 8.10 Cold technology.- Five Cold and Evolution.- 9 Evolution and low temperature.- 9.1 General considerations.- 9.2 Cold and the evolution of endothermy.- 9.3 Cold and extinction.- References.

The isolation response of mussels ( Mytilus edulis L.) exposed to falling sea-water concentrations

The salinity of the water retained within the mantle cavity of mussels after the shell valves have closed in response to falling environmental salinities is influenced by the rate of external salinity change. At high rates of salinity change the retained water salinity is significantly higher than in animals exposed to slowly changing salinities. However, the mantle fluid salinity is not primarily determined by the timing ofx shell valve adduction, but by closure of the exhalant siphon.

Colonisation vs. disturbance: the effects of sustained ice-scouring on intertidal communities

Shoreline plant and animal communities close to a retreating tidewater glacier on the sub-Antarctic island of South Georgia displayed a series of physical and biological gradients from the open sea to the glacier terminus. These included increasing scouring intensity caused by floating and/or grounded ice fragments as well as decreasing diversity and abundance of both macroflora and macrofauna. The correlation between gradients suggests that shoreline scouring intensity can be directly quantified from plant diversity and abundance, and that the colonisation of coastlines exposed to sustained ice-scouring is not stochastic like that following single massive ice-scouring events, but directional like recovery from small scale disturbances. However, colonisation following small-scale disturbance events is much more rapid than that associated with continual scouring. Indeed recovery from continual scouring is so protracted that affected shores are held for a prolonged period at a particular phase of the normal spring annual spring colonisation process by local ice-scouring intensity.

Toxicity of copper oxide nanoparticles in the blue mussel, Mytilus edulis: a redox proteomic investigation

Relatively little is known about the fate and effects of nanomaterials even in relatively simple organisms such as Mytilus edulis. Here, copper oxide nanoparticles (CuO NP) are shown to induce dose-dependent toxic effects at the biochemical, physiological and tissue levels in the blue mussel. Stable CuO NP suspensions were sized by differential light scattering and nanoparticle tracking analysis to yield average particle diameters of approximately 100 nm. These were administered to M. edulis, at doses of 400, 700 and 1000 ppb. Ingested copper was predominantly located in the gill tissue with small amounts in digestive gland. Fifteen coomassie-stained spots were excised from two dimensional gel electrophoresis separations of gill tissue extacts and identified by peptide mass fingerprinting. These contained six unique proteins (alpha- and beta-tubulin, actin, tropomyosin, triosephosphate isomerase and Cu-Zn superoxide dismutase). Of these, two spots (actin and triosephosphate isomerase) showed decreased protein thiols while three (alpha-tubulin, tropomyosin and Cu-Zn superoxide dismutase) showed increased carbonylation which is indicative of protein oxidation of cytoskeleton and enzymes in response to CuO NP. The neutral red retention time (NRRT) assay revealed toxicity due to the CuO NPs which was comparable with toxic metal oxide nanoparticles such as chromium and cobalt. In contrast, non-toxic titanium and gold metal oxide nanoparticles gave no NRRT effects at similar NP concentrations. Histology revealed deposition of pigmented brown cells in response to CuO NP, located predominantly along the mantle and gill margin but also lining digestive tubules and some of the sinuses and distributed throughout the connective tissue and in the adductor muscle.

How and why do flying fish fly

Summary1.The review is concerned mainly with exocoetid flying fish, because little reliable information is available concerning other groups.2.Adult flying fish are of variable size (150–500 mm maximum length) and may be broadly divided into two categories: ‘two-wingers’ (e.g.Fodiator, Exocoetus, Parexocoetus) in which the enlarged pectoral fins make up most of the lifting surfaces, and ‘four-wingers’ (e.g.Cypsilurus, Hirundichthys) in which both pectoral and pelvic fins are hypertrophied.3.The pectoral girdle of flying fish is considerably enlarged by comparison with most teleosts, the coracoid and scapula being particularly hypertrophied.4.The pectoral fins are controlled by two groups of muscles, the lateral muscles that extend the wings, and the medial muscles that furl them. Both groups appear from external appearances to be red (aerobic) muscles.5.A general picture of the flight of an adult four-wing flying fish is presented: fish swim toward the surface at very high speed (< 30 body lengths s-1) with the lateral fins furled, leap through the water surface at a shallow angle, accelerate to take-off speed by taxiing with the lateral fins expanded and the tail beating in the water at up to 50 beats s-1, and enter a free flight that may be prolonged by further taxiing.6.Flying fish do not flap their wings to gain lift, but a whirring noise oroduced during take-off is possibly due to fluttering caused by the coupling together of the contraction of the axial muscles in the production of tail movements, and the action of the pectoral muscles in moving the pectoral fin rays. Alternatively, the noise may be due to a passive, flag-like function of the wings, stemming from their relatively rigid leading edges and flexible trailing edges.7.Flying fish grow in slightly (but significantly) negatively allometric fashion, becoming slimmer with increased body length. On the other hand, wingloading has a markedly positive allometric relationship with standard length because flying fish cannot increase relative wingspan during growth, but have to narrow the wings to improve performance as they fly at greater speeds. Wingloading of flying fish is similar to that of birds and bats, and the largest of flying fish exhibit wingloadings similar to cormorants and pelicans.8.The expanded, flat pelvic fins of four-wingers have evolved, not to increase wing area, but to function as ‘tailplanes’ or ‘stabilizers’ well behing the centre of gravity, with an area some 20–35% of the total lateral fin area, and an angle of incidence less than that of the cambered pectoral fins.9.Flying fish start to exhibit flight at a length of around 50 mm; at smaller sizes surface tension is of importance, limiting flying fish to simple leaps with the fins held against the body by surface tension. Evidence is presented to indicate that smaller flying fish gain positive benefits to their swimming performance from possession of expanded lateral fins.10.For a flying fish of 0.3 m standard length, significant reduction of drag by ground effect will take place at heights below about 0.5 m, prolonging flights and helping take-off.11.Flying fish are in general limited to surface waters warmer than 20–23 °C. Evidence is presented to show that it is unlikely that flying fish are capable of flight at temperatures below 20 °C because of fundamental limitations of muscle function.12.The most recent cladistic analysis supports the view that flying fish evolved from half-beak-like ancestors. They probably developed from elongate epipelagic fishes with hypocercal tails that helped them to swim quickly in the near-surface high-drag zone.13.Flying fish probably fly mainly to escape from predators, particularly dolphin-fishes (Coryphaena hippurus) and ommastrephid squid. An alternative hypothesis of energy conservation is rejected; other possibilities (e.g. migration between food-poor and food-rich areas) are at present supported by limited evidence.