Chondrilla nucula respiration and clearance rates to changing temperature
As a result of climate change, the Mediterranean Sea has been exposed to an increase in frequency and intensity of marine heat waves in the last decades, some of which caused mass mortality events of benthic invertebrates, including sponges. Sponges are an important component of benthic eco-systems and can be the dominant group in some rocky shallow-water areas in the Mediterranean Sea. In this study, we exposed the common shallow-water Mediterranean sponge Chondrilla nucula (Demospongiae: Chondrillidae) to six different temperatures for 24 h, ranging from temperatures experienced in the field during the year (15, 19, 22, 26, 28 °C) and above normal temperatures (32 °C) and metabolic traits (respiration and rate) and behavioural (clearance rate) were measured. Both respiration and clearance rates were affected by temperature. Respiration rates increased at higher temperatures but were similar between 26 and 32 °C treatments. Clearance rates decreased at temperatures > 26 °C, indicating a drop in food intake that was not reflected by respiration rates. This decline in feeding, while maintaining high respiration rates, may indicate a negative energy balance that could affect this species under chronic or repeated thermal stress exposure. C. nucula will probably be a vulnerable species under climate change conditions, affecting its metabolic per-formance, ecological functioning and the ecosystem services it provides.
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The data have been obtained through specific laboratory experiments under controlled conditions.