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The rhythm of life on earth is shaped by seasonal changes in the environment. Plants and animals show profound annual cycles in physiology, health, morphology, behaviour and demography in response to environmental cues. Seasonal biology impacts ecosystems and agriculture, with consequences for humans and biodiversity. Human populations show robust annual rhythms in health and well-being, and the birth month can have lasting effects that persist throughout life. This review emphasizes the need for a better understanding of seasonal biology against the backdrop of its rapidly progressing disruption through climate change, human lifestyles and other anthropogenic impact. Climate change is modifying annual rhythms to which numerous organisms have adapted, with potential consequences for industries relating to health, ecosystems and food security. Disconcertingly, human lifestyles under artificial conditions of eternal summer provide the most extreme example for disconnect from natural seasons, making humans vulnerable to increased morbidity and mortality. In this review, we introduce scenarios of seasonal disruption, highlight key aspects of seasonal biology and summarize from biomedical, anthropological, veterinary, agricultural and environmental perspectives the recent evidence for seasonal desynchronization between environmental factors and internal rhythms. Because annual rhythms are pervasive across biological systems, they provide a common framework for trans-disciplinary research.

It has been well established that sponges play an important role in benthic ecology as abundant, large, sessile filter-feeders. However, the ecology of one group, the Hexactinellida, whose electrophysiology and cell biology is quite distinct from other Porifera, has received little attention due to the inaccessibility of their preferred deep water habitat. Now, a three year study of a population of the hexactinellid sponge Rhabdocalyptus dawsoni (Lambe, 1892) has been carried out in the fjords of British Columbia, Canada. Rhabdocalyptus was found to have a patchy distribution in Saanich Inlet, British Columbia, with local abundance reaching 5.3 individuals m−2. The mean length of the tube-like sponges in the inlet was 32 cm (an equivalent of 5.8 l volume) although sponges could reach 87 cm in length (36 l volume). The average growth rate of sponges measured over the course of 3 years was 1.98 cm year−1 (min. −0.76 cm year−1, max. 5.7 cm year−1) or 167 ml year−1 (min. −537 ml year−1, max. 856 ml year−1). The rate of tissue regeneration after artificial wounding in the field was 0.05±0.03 cm2 day−1, some 40 times the rate of growth. No recruitment was observed during the study, but mortality of large individuals was seen. Using the calculated growth rate (average rate of increase in volume), the age of an average-sized sponge was estimated to be 35 years. With the assumption that growth rate is constant, large individuals (1 m in length) were estimated to be 220 years old. All sponges showed seasonal trends in sloughing of the debris-covered outer spicules during winter months (November to February). Increase in outer spicule coat occurred from March to October and sloughing corresponded to the end of seasonal phytoplankton blooms in October or November. These data suggest that hexactinellid sponges have life history strategies and growth rates similar to those of massive tropical and temperate demosponges and that, despite their deep water habitat, they experience seasonality which influences their growth rates and perhaps reproductive period.

A detailed ste-by-step description of one set of solutions to the engineering problems associated with connecting a piece of non-standard peripheral equipment to a small fast data processor is given. The peripheral unit is a twelve-bit-plus-sign analog-to-digital converter with a programed multiplexer. The data processor is a Systems Engineering Laboratories computer with a 24-bit word length and 1.75-μs cycle time. The software or 'programing' aspect of the interconnection is also discussed. This report was prepared by a student assistant and describes the work done during his intersemester employment at the Radio and Electrical Engineering Division, National Research Council.

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