Effects of ocean acidification on the swimming ability, development and biochemical responses of sand smelt larvae

Ocean acidification, recognized as a major threat to marine ecosystems, has developed into one of the fastest growing fields of research in marine sciences. Several studies on fish larval stages point to abnormal behaviours, malformations and increased mortality rates as a result of exposure to increased levels of CO2. However, other studies fail to recognize any consequence, suggesting species-specific sensitivity to increased levels of CO2, highlighting the need of further research. In this study we investigated the effects of exposure to elevated pCO2 on behaviour, development, oxidative stress and energy metabolism of sand smelt larvae, Atherina presbyter. Larvae were caught at Arrábida Marine Park (Portugal) and exposed to different pCO2 levels (control: ~600μatm, pH=8.03; medium: ~1000μatm, pH=7.85; high: ~1800μatm, pH=7.64) up to 15days, after which critical swimming speed (Ucrit), morphometric traits and biochemical biomarkers were determined. Measured biomarkers were related with: 1) oxidative stress - superoxide dismutase and catalase enzyme activities, levels of lipid peroxidation and DNA damage, and levels of superoxide anion production; 2) energy metabolism - total carbohydrate levels, electron transport system activity, lactate dehydrogenase and isocitrate dehydrogenase enzyme activities. Swimming speed was not affected by treatment, but exposure to increasing levels of pCO2 leads to higher energetic costs and morphometric changes, with larger larvae in high pCO2 treatment and smaller larvae in medium pCO2 treatment. The efficient antioxidant response capacity and increase in energetic metabolism only registered at the medium pCO2 treatment may indicate that at higher pCO2 levels the capacity of larvae to restore their internal balance can be impaired. Our findings illustrate the need of using multiple approaches to explore the consequences of future pCO2 levels on organisms.

The practices of existential psychotherapists: Development and application of an observational grid

Within the major therapeutic paradigms, observational instruments have been developed to assess orientation-specific interventions or processes. However, to date, no such instrument exists to assess existential practices. Recent research indicates the key practices of existential therapists, and forms an empirical basis on which to develop an observatory grid. This paper describes the development of such a grid, and its exploratory testing with eight clients of four Portuguese existential psychotherapists. A total of 32 sessions were observed and both speaking turn and whole-session analysis showed that it was feasible to assess existential therapy using the instrument, although psychometric findings recommend further refinement of the tool. Session-rating data suggest that the chief practices applied by existential therapists were relational, followed by the use of hermeneutic interventions and reformulations. Interventions based on phenomenological and existential assumptions were observable in practice but limited in frequency. Further refinements and developments of the observational grid, together with additional research – using a range of therapists from different schools of existential therapy – are recommended.