100 research outputs found
Making overall dynamic body acceleration work: on the theory of acceleration as a proxy for energy expenditure
No full textGleiss, A., Wilson, R. P., Shepard, E. L. C. (2011). Making dynamic body acceleration work: on the theory of acceleration as a proxy for energy expenditure. Methods in Ecol. Evol. 2; 23-33
Multi-Channel Data-Logging: Towards Determination of Behaviour and Metabolic Rate in Free-Swimming Sharks
No full textGleiss, A. C., Gruber, S. H., Wilson, R. P. (in press). Multi-channel data-logging; Towards determination of behaviour and metabolic rate in free-swimming sharks. In; Reviews: Methods and technologies in Fish Biology and Fisheries. (eds Nielsen, J. et al.). (In press)
Behaviour and buoyancy regulation in the deepest diving reptile: The leatherback turtle
No full textFossette, S. Gleiss, A. C., Myers, A. E., Garner, S., Liebsch, N., Whitney, N. M., Hays, G. C., Wilson, R. P., Lutcavage, M. E. (2010). Behaviour and buoyancy regulation in the deepest-diving reptile: the leatherback turtle. J. Exp. Biol. 213: 4074-4083
Evaluating the constraints governing activity patterns of a coastal marine top predator
No full textByrnes EE, Daly R, Leos-Barajas V, Langrock R, Gleiss AC. Evaluating the constraints governing activity patterns of a coastal marine top predator. Marine Biology. 2021;168(1): 11
The physiological and ecological effects of temperature and oxygen on an estuarine fish
No full textTemperature and oxygen are the primary abiotic variables controlling and limiting the metabolic capacity of fishes. This has been attributed to the strong influence of each variable on aerobic scope; the capacity of organisms to distribute energy across physiological functions. This study incorporates laboratory quantification of aerobic scope with field acoustic accelerometry to determine the relative importance of both temperature and oxygen to an estuarine teleost, the black bream (Acanthopagrus butcheri). In respirometry experiments, A. butcheri were found to display remarkably high thermal tolerance, maintaining stable aerobic scope across a 9°C thermal window. However, their aerobic scope was heavily reduced with reductions in oxygen availability, reaching a critical oxygen level at ~30% DO. The ecological importance of this was quantified in wild fishes as, whilst temperature displayed little effect on movement dynamics, the presence of hypoxia resulted in significant habitat compression, with bream restricted to shallow, oxygenated microhabitats. Under such compression, bream are likely to be at increased risk of predation and the negative effects of increased density, including competition and disease. These results provide empirical evidence for the hypothesis that hypoxia is a key driver of A. butcheri growth rates within the Swan River Estuary. It also highlights the population’s vulnerability to hypoxic episodes, which are expected to increase in both extent and frequency as a result of anthropogenically-enhanced eutrophication and climate change
Infectious disease and changing climates: Quantifying threats to freshwater fish from multiple stressors
No full textAustralia has a highly endemic freshwater fish fauna that is threatened by climate change and a number of other anthropogenic processes. Climate change represents a major threat to freshwater fishes, directly through increasing water temperature and decreasing water flow, and indirectly by exacerbating existing stressors, such as infectious disease. This study investigated the interactive effects of increasing water temperature and infectious diseases on two freshwater parasite/host systems: (1) western pygmy perch, Nannoperca vittata, an endemic temperate species to south-western Australia, infected with the bacterium Photobacterium damselae damselae; and (2) guppy, Poecilia reticulata, an introduced subtropical species, infected with Streptococcus iniae. Bacterial pathogenicity and growth rate, and fish metabolic rate and immune response, were measured over a range of temperatures between 16 and 28°C. The virulence of both P. damselae damselae to N. vittata and S. iniae to P. reticulata increased with temperature, being greatest at 28°C. Increasing water temperature, over the range from 16 - 28°C, also increased the in vitro population growth rate of both bacterial species, but over the same temperature range, there were contrasting effects on the immune response of the two host species. For N. vittata, when challenged with P. damselae damselae, the increase in respiratory burst activity and lysosome content was greatest at 17°C, while for P. reticulata challenged with S. iniae, the increase in these two immune parameters was greatest at 28°C. Exposure to bacterial infection increased both standard metabolic rate (SMR) and maximum metabolic rate (MMR) in N. vittata and P. reticulata, being greatest at lower temperatures (17°C) for N. vittata and at higher temperatures (24°C) for P. reticulata. The increase in MMR with exposure to bacteria, most marked in N. vittata, was unexpected and warrants further investigation. These data suggest that increasing water temperatures as a result of climate change may produce a thermal mismatch in performance between native freshwater fish species and their bacterial parasites
Interaction of disease and temperature on the aerobic scope of freshwater fish and implications for changing climates
No full textClimate change is a major threat to both freshwater and marine ecosystems on a global scale. There is evidence that for aquatic pathogens and parasites, increasing water temperatures will favour increasing transmission rates and virulence. Increasing water temperature may stress fish and transiently compromise the immune system, exacerbating the effects of infection. The high energy costs of an upregulated immune response will have consequences on other physiological processes such as growth and reproduction.
In order to study the effects of temperature on pathogenicity, a bioassay to challenge the Australian native freshwater pygmy perch, Nannoperca vittata with a bacterium Photobacterium damselae damselae was carried out. The bioassay was carried out at two temperatures; 17°C, thought to be the optimum for fish survival and growth, and 28°C, presumed to be approaching the upper critical limit for the species. Nannoperca vittata was found to be susceptible to infection by P. damselae damselae, the first time that infection has been demonstrated in native Australian freshwater fishes. The effect concentration that caused mortalities in 50% of the population (EC50) was lower at 28°C (4.82x105 CFU ml-1) than at 17°C (2.81x106 CFU ml-1). Fish mortalities were significantly greater and times to death were significantly shorter at 28°C than at 17°C and this is the first time that this has been demonstrated experimentally for P. damselae damselae.
Following the pathogenicity trial, the aerobic scope of exposed versus non-exposed pygmy perch of both 17°C and 28°C experimental groups was determined in a respirometer. Aerobic scope is defined as the difference between maximum metabolic rate and standard metabolic rate. The aerobic scope was greater in exposed than in unexposed fish at 17°C and conversely, greater in unexposed than in exposed fish at 28°C.. This difference occurred because standard metabolic rate increased with exposure at both temperatures, whereas maximum metabolic rate increased at 17°C, but not at 28°C. The increase in standard metabolic rate at both temperatures was expected as a consequence of an upregulated immune response following exposure to the bacterium. The difference in maximum metabolic rate is hypothesised to be a consequence of a compensatory increase in oxygen carrying capacity, which is counteracted by a persistent immune response at 28 but not at 17°C. This hypothesis requires further testing.
The results from this study suggest, firstly, that fish are less tolerant of infection at higher water temperatures and secondly, that a combination of higher water temperature and increased exposure to pathogens may decrease aerobic scope and therefore fitness. This study showed that higher temperatures decrease aerobic scope in fish, thus suggesting that rising temperatures with global warming may have the same effect. This is the first study to demonstrate such a response in an Australian native freshwater fish. Further research in this field is urgently required to enable conservation management plans that address the threats posed to native freshwater fish species through climate change
Identification of animal movement patterns using tri-axial accelerometry
No full textShepard ELC, Wilson RP, Albareda D, Gleiss A, Gómez Laich A, Halsey LG, Liebsch N, Macdonald DW, Morgan DT, Myers AE, Newman C, Quintana F (2008) Identification of animal movement patterns using tri-axial accelerometry. Endangered Species Research 10; 47-60
New technology highlights the importance of scale in the foraging behaviour of a pelagic predator
No full textThe effects of temperature and swimming speed on the metabolic rate of the nurse shark (Ginglymostoma cirratum, Bonaterre)
No full textSharks and other top predators have a substantial impact on their ecosystems through trophically mediated effects, and understanding the scope of this impact is essential to forming an accurate picture of energy flow within an ecosystem. One of the most important factors to consider when assessing a predator's impact on their ecosystem is metabolic rate, which is dependent on a number of environmental factors including temperature, as well as underlying physiological and anatomical characteristics. Here the standard (SMR) and routine metabolic rates (RMR) and swimming dynamics of the nurse shark (Ginglymostoma cirratum, Bonaterre) were assessed using a static respirometer over two experimental temperatures (23 and 30°C). The metabolic rates measured here represent the lowest reported for any shark species to date. Mean (±SD) SMRs at 23°C and 30°C were 36±8 and 60±17mgO2kg-1h-1, and mean RMRs were 95±15 and 138±21mgO2kg-1h-1, respectively. The Q10 for SMR was 2.42 between 23 and 30°C. Minimum cost of transport (COTmin) at 23°C was 68mgO2kg-1km-1, where swimming speed was 0.33BLs-1. The COTmin increased to 81mgO2kg-1km-1 at 30°C, where swimming speed was 0.44BLs-1. The proportional cost of activity, or the cost of activity relative to SMR, was greater compared to other elasmobranchs, and nearly twice that of most ram ventilating shark species. These results highlight the sedentary nature of nurse sharks and suggest that they are energetically suited for a minimally active lifestyle
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