Stakeholder perspectives on the importance of water quality and other constraints for sustainable mariculture

Aquaculture, including marine aquaculture (mariculture), is the fastest growing food production sector globally and is expected to play a key role in delivering future food security. A potential factor limiting growth of the aquaculture industry, however, is the maintenance of good water quality, on which all forms of aquaculture depend. This is particularly challenging in ‘open’ coastal and estuarine systems and requires engagement with a wide range of stakeholders that can influence water quality. We applied a semi-quantitative method (Q-method) to capture and evaluate perspectives across diverse stakeholders in order to address the overarching question: “How do stakeholders rank water quality issues and management options versus other issues and actions for ensuring the sustainability of shellfish mariculture in South West England?” Results from this regional case study were used to highlight key issues and knowledge gaps that have national and international relevance. Stakeholders were found to hold distinct perspectives (P1−3), but there was general consensus that good water quality is essential for sustainable aquaculture, and that there is a need for better understanding of spatial and temporal variations in land use throughout catchments to ensure effective water quality management. Stakeholder engagement highlighted the importance of managing anthropogenic and environmental (climatic) pressures on land and water through agri-environment and urban planning policy in order to ensure sustainable food production, including from mariculture

Scaling physiological measurements for individuals of different body size.

This paper examines how selected physiological performance variables, such as maximal oxygen uptake, strength and power, might best be scaled for subject differences in body size. The apparent dilemma between using either ratio standards or a linear adjustment method to scale was investigated by considering how maximal oxygen uptake (l.min-1), peak and mean power output (W) might best be adjusted for differences in body mass (kg). A curvilinear power function model was shown to be theoretically, physiologically and empirically superior to the linear models. Based on the fitted power functions, the best method of scaling maximum oxygen uptake, peak and mean power output, required these variables to be divided by body mass, recorded in the units kg 2/3. Hence, the power function ratio standards (ml.kg-2/3.min-1) and (W.kg-2/3) were best able to describe a wide range of subjects in terms of their physiological capacity, i.e. their ability to utilise oxygen or record power maximally, independent of body size. The simple ratio standards (ml.kg-1.min-1) and (W.kg-1) were found to best describe the same subjects according to their performance capacities or ability to run which are highly dependent on body size. The appropriate model to explain the experimental design effects on such ratio standards was shown to be log-normal rather than normal. Simply by taking logarithms of the power function ratio standard, identical solutions for the design effects are obtained using either ANOVA or, by taking the unscaled physiological variable as the dependent variable and the body size variable as the covariate, ANCOVA methods