Common Sole Larvae Survive High Levels of Pile-Driving Sound in Controlled Exposure Experiments

In view of the rapid extension of offshore wind farms, there is an urgent need to improve our knowledge on possible adverse effects of underwater sound generated by pile-driving. Mortality and injuries have been observed in fish exposed to loud impulse sounds, but knowledge on the sound levels at which (sub-)lethal effects occur is limited for juvenile and adult fish, and virtually non-existent for fish eggs and larvae. A device was developed in which fish larvae can be exposed to underwater sound. It consists of a rigid-walled cylindrical chamber driven by an electro-dynamical sound projector. Samples of up to 100 larvae can be exposed simultaneously to a homogeneously distributed sound pressure and particle velocity field. Recorded pile-driving sounds could be reproduced accurately in the frequency range between 50 and 1000 Hz, at zero to peak pressure levels up to 210 dB re 1µPa2 (zero to peak pressures up to 32 kPa) and single pulse sound exposure levels up to 186 dB re 1µPa2s. The device was used to examine lethal effects of sound exposure in common sole (Solea solea) larvae. Different developmental stages were exposed to various levels and durations of pile-driving sound. The highest cumulative sound exposure level applied was 206 dB re 1µPa2s, which corresponds to 100 strikes at a distance of 100 m from a typical North Sea pile-driving site. The results showed no statistically significant differences in mortality between exposure and control groups at sound exposure levels which were well above the US interim criteria for non-auditory tissue damage in fish. Although our findings cannot be extrapolated to fish larvae in general, as interspecific differences in vulnerability to sound exposure may occur, they do indicate that previous assumptions and criteria may need to be revised

Spatio-temporal models in animal population dynamics

Population dynamics is the study of how and why populations of animals change in distribution and abundance. Thus, the aims of the science of population dynamics are twofold: to document the empirical patterns of population distribution and change, and to determine the mechanisms underlying those observed patterns. Population dynamics data typically have rich and complex spatio-temporal patterns. Modern and flexible statistical methods are needed to describe these patterns, and for the sound estimation of parameters in realistic mathematical models of spatio-temporal population dynamics. Of particular importance has been the development over the past decade of modern computational statistical methods, such as Markov chain Monte Carlo (McMC), that enable rigorous parameter estimation for more realistic models. The work as reported in this thesis has evolved around three case studies, each involving a long-term data set of estimated abundance’s of a species at different locations over time, and a specific set of questions of interest: 1)  Linking the spatio-temporal variation in recruitment of the Atlantic puffin (Fractercula arctica) to the spatio-temporal variation in densities of nesting herring gulls (Larus argentatus) and lesser black-backed gulls (Larus fuscus) within the Isle of May natural nature reserve. 2)  The use of flexible statistical tools to investigate coincident changes in the spatial and temporal dynamics of cyclic populations of field voles (Microtus agrestis). 3)  Investigating the metapopulation dynamics of water voles (Arvicola terrestris) in the Scottish uplands using stochastic patch occupancy models. In each case study, the central aim was to formulate mathematical models that describe the spatio-temporal dynamics of the animal populations, and to develop and investigate the uses of flexible statistical methods that can be used to inform these models using the data.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Thermal Preference of Juvenile Dover Sole (Solea solea) in Relation to Thermal Acclimation and Optimal Growth Temperature

Dover sole (Solea solea) is an obligate ectotherm with a natural thermal habitat ranging from approximately 5 to 27°C. Thermal optima for growth lie in the range of 20 to 25°C. More precise information on thermal optima for growth is needed for cost-effective Dover sole aquaculture. The main objective of this study was to determine the optimal growth temperature of juvenile Dover sole (Solea solea) and in addition to test the hypothesis that the final preferendum equals the optimal growth temperature. Temperature preference was measured in a circular preference chamber for Dover sole acclimated to 18, 22 and 28°C. Optimal growth temperature was measured by rearing Dover sole at 19, 22, 25 and 28°C. The optimal growth temperature resulting from this growth experiment was 22.7°C for Dover sole with a size between 30 to 50 g. The temperature preferred by juvenile Dover sole increases with acclimation temperature and exceeds the optimal temperature for growth. A final preferendum could not be detected. Although a confounding effect of behavioural fever on temperature preference could not be entirely excluded, thermal preference and thermal optima for physiological processes seem to be unrelated in Dover sol

Dimensions and settings of the preference chamber.

<p>Dimensions and settings of the preference chamber.</p

Fish distribution over the preference chamber.

<p>Fish distributions during non-gradient, acute preference and 24 h preference observations are expressed as odds ratios (proportion of temperature zones used dived by the proportion of temperature zones available) and are presented for fish acclimated to 18°C (A), 22°C (B) and 28°C (C). Fish distribution was non-random during all non-gradient observations (MANOVA, p = 0.002) without differences among temperature acclimation treatments (MANOVA, p = 0.42). Fish distribution observed during acute preference observations differed significantly from the non-gradient observations (MANOVA, p<0.001). Fish distribution during 24 h preference observations differed significantly from the non-gradient (MANOVA, p<0.0001) as well as the acute preference observations (MANOVA, p<0.002). Among acclimation temperature treatments fish distribution differed during acute preference observations (MANOVA, p = 0.01) but not during the 24 h preference observations (MANOVA, p = 0.21).</p

Schematic presentation of the preference chamber.

<p>Top view (A) presents schematically the water flows (arrows) and the main elements: 1) water inflow, 2) mixing channel, 3) swimming channel, 4) effluent channel, 5) central section with water drain. Top view (B) presents schematically the temperature gradient in the preference chamber.</p

Results of the second order polynomial regression for specific growth rate (SGR), total feed intake (TFI) and feed conversion ratio (FCR).

<p>Results of the second order polynomial regression for specific growth rate (SGR), total feed intake (TFI) and feed conversion ratio (FCR).</p

Water temperatures in the preference chamber during the preference tests for the three acclimation temperatures.

<p>Mean (SD, n = 6) water temperatures in the five temperature zones during the non-gradient observation, installation of the temperature gradients and acute preference observations are presented for the tests conducted with fish acclimated to 18°C (A), 22°C (B) and 28°C (C). Water temperatures during the 24 h preference observation equalled the water temperatures during the acute preference observations (not shown).</p