Complexity scientists often express the need for the development of a theory of complexity. One of the major problems on the way toward such a theory is the lack of a generally agreed on definition of complexity. In this article it is proposed that, whatever definition one might one day agree on, contextuality and radical openness are essential features of complexity. Both properties are clarified by means of an example and implications for a future theory of complexity are discussed.

Effects of elevated seawater temperatures on deep-water benthos has been poorly studied, despite reports of increased seawater temperature (up to 4 °C over 24 hrs) coinciding with mass mortality events of the sponge Geodia barretti at Tisler Reef, Norway. While the mechanisms driving these mortality events are unclear, manipulative laboratory experiments were conducted to quantify the effects of elevated temperature (up to 5 °C, above ambient levels) on the ecophysiology (respiration rate, nutrient uptake, cellular integrity and sponge microbiome) of G. barretti. No visible signs of stress (tissue necrosis or discolouration) were evident across experimental treatments; however, significant interactive effects of time and treatment on respiration, nutrient production and cellular stress were detected. Respiration rates and nitrogen effluxes doubled in responses to elevated temperatures (11 °C & 12 °C) compared to control temperatures (7 °C). Cellular stress, as measured through lysosomal destabilisation, was 2–5 times higher at elevated temperatures than for control temperatures. However, the microbiome of G. barretti remained stable throughout the experiment, irrespective of temperature treatment. Mortality was not evident and respiration rates returned to pre-experimental levels during recovery. These results suggest other environmental processes, either alone or in combination with elevated temperature, contributed to the mortality of G. barretti at Tisler reef.

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In recent years the concept of the circular economy gained prominence in EU policy-making. The circular economy promotes a future in which linear 'make-use-dispose' cultures are replaced by more circular models. In this paper, we use the concept of sociotechnical imaginaries to ask how an imaginary of circularity has been assembled and stabilized, which imaginative resources were drawn on, and how goals, priorities, benefits and risks haven been merged with discourses of innovation, sustainability and growth. Drawing on policy documents and interviews with policy officers of the European Commission, we argue that the monitoring framework and indicator development function as a site collective imagination in which desirable 'circular' futures are coproduced. These futures are imagined to provide novel opportunities for the private sector and to generate jobs and economic growth while at the same time improving the natural environment as measured by selected environmental indicators.