Jennifer R. Hoffman

INTERACTIONS BETWEEN UV RADIATION AND TEMPERATURE LIMIT INFERENCES FROM SINGLE‐FACTOR EXPERIMENTS1

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.

Designing Climate-Smart Conservation: Guidance and Case Studies

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.

RISK AND THE EVOLUTION OF CELL-CYCLE DURATIONS OF EMBRYOS

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.

Climate Change and Its Effects

For better or worse, climate change is affecting many elements of the world around us. We can incorporate this reality into our planning or we can ignore it, but the climatic changes currently under way will continue regardless. Species ranges will continue to shift, the timing of seasonal events will continue to change, and weather patterns will no longer follow familiar paths. If we fail to look at how our policies and practices might be affected by these changes, we run the risk of investing time, money, and political capital in plans that are at best irrelevant and at worst maladaptive. This is true for any sector or activity influenced by climatic conditions, be it resource management, development, or conservation. Climate change is not the only important consideration for conservation or natural-resource planning, but ignoring it would be as shortsighted as ignoring the possible influence of land use, pollution, or invasive species.

Assessing Vulnerability to Climate Change

Thus far, this book has focused on why adapting to climate change is important, and on general principles for actually doing it. How can we turn all this into actual projects, or apply it to our own work? The first step is to assess the ways in which our goals and the species, places, and processes we care about are vulnerable to climate change. Understanding sources of vulnerability forms the basis for developing adaptation strategies; knowing the relative vulnerability of different species, places, or resources can help to prioritize where and how to focus our efforts.

The Role of Connectivity

Increasing connectivity is perhaps the most frequently recommended adaptation strategy for maintaining biodiversity in the face of climate change (Heller and Zavaleta 2009). Based on well-documented negative effects of habitat loss and fragmentation on species richness, practitioners have long assumed that the ability of species to move easily across habitats must play an important role in maintaining biodiversity. In the face of climate change, connectivity may become even more important, given its potential to support natural adaptive responses. Connectivity along climatic gradients may facilitate populations’ ability to track appropriate climatic conditions, for instance, or allow the flow of genes from warm-adapted populations to those in cooler but warming parts of a species’ range.

Integrating the Needs of Nature and People

The focus of this book is the conservation and management of natural resources. Yet even practitioners whose focus is not human welfare would benefit from incorporating human needs and uses into their planning. The alternatives—walling off protected areas, policing them vigorously, expecting people to obey laws regardless of their own circumstances, or simply ignoring human concerns altogether—are frequently impractical, expensive, or ineffective. This will be particularly true as climate change decreases the reliability of systems on which people have come to depend. Thus climate change vulnerability assessments and adaptation planning for species, habitats, and ecosystems should consider how humans might respond to climate change or its effects, and how this might influence the vulnerability of natural systems to climate change. Adaptation plans that anticipate and incorporate the opportunities and challenges resulting from human responses are almost certainly more robust than those that do not.

Regulating Pollutants in a Changing World

Societies have made great strides in reducing the damage of environmental pollutants by enacting regulations, implementing testing and monitoring criteria, and developing treatment strategies to reduce toxicity and damage. Although new challenges do arise (e.g., low-dose toxicity issues with some plasticizers), efforts to date have led to higher air, water, and soil quality in many regions. Climate change, however, points to a glaring limitation of our current regulatory system. The testing procedures on which current regulatory limits are based do not generally reflect real-world exposure conditions, and certainly do not reflect a world in which temperature, salinity, and a host of other factors are changing as a result of climate change. Although regulatory limits for some pollutants specifically address season or local water chemistry, this is not the norm.

Strengthening Protected Areas

Protected areas have long been viewed as a primary tool of conservation biology (Groom et al. 2006). They are conceptually simple—protect space in which species or habitats of concern can exist—and legally simple—designate space and regulate allowable uses. However, as climate change alters the conditions that allow species and habitats currently in protected areas to continue to exist there, we may need to rethink protected area utility and implementation. In particular, we need to consider, as part of our climate change adaptation strategy, ways in which protected areas are vulnerable to climate change and ways in which we can make them more robust and useful as tools of adaptation.

Adapting Governance for Change

Over time, communities develop institutions and processes for making decisions, setting policies, or sharing power that work for their particular circumstances. When social, economic, technological, or ecological conditions are relatively stable, rigid governance structures can work well, allowing sustainable use of natural resources for decades or centuries. When conditions change rapidly, however, rigid governance structures frequently weaken or fail. To govern and manage effectively in the face of rapid change, we need legal and regulatory mechanisms that facilitate responsive, effective conservation and management.