Since the 1920s, E. superba is one of the best studied species in the Southern Ocean in terms of their general biology. The main driver for this research focus has been the fisheries’ requirements for stock forecasting and conservation measures. Nowadays this is joined by concerns over climate change effects and the requirement to take a more holistic view to understand food web structures. So far, however, we do not have a clear understanding of the physiological response of krill and hence their adaptability to cope with ongoing environmental changes, caused by the anthropogenic carbon emissions. This is due to the extreme lack of intense studies on krill physiology, especially of their larval stages in relation to their seasonal environment. A major aim of this book chapter is on the one hand to summarize how physiological functions such as lipid accumulation and utilisation, metabolic activity and growth change with ontogeny and season and to demonstrate which environmental factors are the main drivers for seasonal variability of these functions in adult and larval krill. On the other hand, we draw the attention to the importance of photoperiod (day length) as an entrainment cue for endogenous rhythms and clocks in the life cycle of krill. Furthermore, we give an overview of the current knowledge on the impact of elevated seawater temperature and ocean acidification on krill.

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Physiology of Euphausia superba

Autotomy and regeneration of the large male cheliped and/or numerous walking legs disrupts normal growth parameters in the fiddler crab, Uca pugilator. Growth of the regenerating structures is accelerated, while growth of non-regenerating structures can be slowed or inhibited. These perturbations are not limited to the molt immediately following autotomy but also can affect growth allometry for two or more molt cycles subsequent to autotomy. The disruptions are due to variations in the distribution of body fluids following molt.

Penny M. Hopkins

Papers

Regeneration and Relative Growth in the Fiddler Crab