The global environment is changing. Substantial shifts in temperature, rainfall, cloud cover, and UV radiation (UVR) are all predicted as a result of anthropogenic activity. Although the actual and potential effects of changes in single environmental variables are being studied intensively, the interactive effects of multiple stressors have received little attention. Here we offer the first experimental evidence of interactive effects between UVR and temperature on germination and growth in multicellular organisms. To address the question of how temperature affects survival and growth of organisms in the presence of UVR, we exposed early life stages of two species of intertidal algae, Alaria marginata Postels et Ruprecht and Fucus gardneri Silva, to four levels of UVR at three temperatures for 56 h. PAR and day length (12:12‐h light:dark) were held constant across all treatments. UVR levels bracketed natural levels, and temperatures were within the range of ambient temperatures. Designated endpoints were germination rate and cell number, and we recorded mortality where survival was nil. Our results support the hypothesis that temperature mediates the net biological effect of UVR and vice versa. For instance, spores of A. marginata were able to survive and grow at 15° C at all UV levels and at 10° C in the absence of UVR but were unable to survive at 10° C in the presence of high levels of UVR. Our results suggest that the ability to predict the effects of global change hinges on understanding interactions among environmental variables, imposing strict limits on inferences made from single‐factor experiments.

To be successful, conservation practitioners and resource managers must fully integrate the effects of climate change into all planning projects. Some conservation practitioners are beginning to develop, test, and implement new approaches that are designed to deal with climate change. We devised four basic tenets that are essential in climate-change adaptation for conservation: protect adequate and appropriate space, reduce nonclimate stresses, use adaptive management to implement and test climate-change adaptation strategies, and work to reduce the rate and extent of climate change to reduce overall risk. To illustrate how this approach applies in the real world, we explored case studies of coral reefs in the Florida Keys; mangrove forests in Fiji, Tanzania, and Cameroon; sea-level rise and sea turtles in the Caribbean; tigers in the Sundarbans of India; and national planning in Madagascar. Through implementation of these tenets conservation efforts in each of these regions can be made more robust in the face of climate change. Although these approaches require reconsidering some traditional approaches to conservation, this new paradigm is technologically, economically, and intellectually feasible.

Abstract. Embryos at low risk evolve slower development rates. In seven independent evolutionary contrasts for marine invertebrates (two in asteroids, three in gastropods, one each in phoronids and brachiopods) the more protected embryos had longer cell cycles from first to second cleavage than less protected planktonic embryos. Protected embryos had longer cell cycles even when protected eggs were smaller than planktonic eggs. In an eighth contrast, among tunicates, the embryonic cell cycle was unrelated to brooding and nearly proportional to egg size, but the literature provides examples of especially slow development in some brooding tunicates. The faster development of planktonic embryos is consistent with published estimates of greater mortality rates for planktonic larvae than for embryos in broods or egg masses. Examples from the literature for annelids, arthropods, holothuroids, and chordates also demonstrated longer embryonic cell cycles for more protected embryos with no consistent effect of egg size on cell-cycle duration. Longer cell cycles presumably reduce the benefits of protecting offspring because of longer exposure to whatever hazards remain, but slow development may permit compensating benefits. Hypothesized benefits of longer cell cycles include less maternal investment in rate-limiting materials, more or different transcription, and correction of errors. Such trade-offs are independent of feeding and growth and are influenced by parental protection.