WINGS ESSAYS ON INVERTEBRATE CONSERVATION THE XERCES SOCIETY FALL 2007 CONTENTS Introduction: Invertebrates and Global Warming Scott Hoffman Black Page 3. Wetland Invertebrates: What Happens When the Pond Is Half-Empty? John H. Matthews Water temperature and volume, both critical to the development and emergence of dragonfly larvae in wetlands, are changing as global warming increases. Page 5. Bleached Out: Coral Reefs Under Stress David Obura Tropical coral reefs are one of the first ecosystems to show significant changes due to changing climate. Page 11. Beer for Butterflies: Tracking Global Warming Matthew L. Forister As scientists study the impacts of global warming upon butterflies, patterns are emerging of both shifts in range and changes in the timing of life-history events. The consequences for these tiny creatures may be enormous. Page 15. For Marine Worms, Timing Is Everything Andrew Lawrence Marine worms are a hugely important link in the food chain of intertidal areas. In- creasing water temperatures place their future breeding success at risk. Page 19. Impacts of Global Warming on Pollinators David Inouye Climate change is altering the phenology of both plants and their insect visitors, breaking the link between the two and putting at risk the essential service of pol- lination. Page 24. Xerces News Protecting native bumble bees and other pollinators, wetland conservation efforts, and a Butterfly-A-Thon; and new staff members join the Xerces Society. Page 28. 2 WINGS Introduction: Invertebrates and Global Warming Scott Hoffman Black Not long ago, as I was hiking along a collecting, and a prolonged drought roaring stream on my way up to Col- that was thought to be drying out the orado’s Red Cloud Peak, my mind wan- habitat, this butterfly had recently been dered back to the summer of 1995. I had listed as an endangered species. been hired by the Colorado Natural The Uncompahgre fritillary lives Heritage Program to help organize a only in alpine meadows. Thought to search for the Uncompahgre fritillary have been broadly distributed near gla- (Boloria improba acrocnema). With few cial margins during the last ice age, the known populations and multiple threats butterfly is now confined to small including sheep grazing, potential over- patches of habitat above thirteen thou- The San Juan Mountains of Colorado are home to the Uncompahgre fritillary (Boloria improba acrocnema), one of many alpine insects that are vulnerable to climate destabi- lization. Warming climate may spell extinction for many of these species. Photograph by Scott Hoffman Black. FALL 2007 3 sand feet in the San Juan Mountains of but will it really be the same without a southwestern Colorado, where cool and species that has resided here for thou- wet environments have persisted to the sands of years? present. The Uncompahgre fritillary is not On my recent trip, I was heading up the only invertebrate facing a changing to see how things had changed in the environment. In this issue of Wings, we last twelve years. Although it was a lit- explore multiple aspects of climate de- tle late in the year, I hoped to see a few stabilization from the perspective of in- late-season stragglers. The area looked vertebrate conservation. Included are es- much the same as it did in 1995. Snow says on how warming temperatures are willow (the Uncompahgre fritillary’s lar- already leading to bleaching corals and val hostplant) was still abundant. There shifts in butterfly ranges. You will see were bumble bees, flies, and several spe- that global warming may lead to the ex- cies of butterflies including the arctic tinction of some butterflies and aquat- fritillary (Boloria chariclea), Uncompah- ic invertebrates. It may also lead to the gre’s sister species. loss of some marine worms that are an I carefully made my way through important food source for many birds the habitat hoping to spot an adult Un- and marine animals. In short, global compahgre. I thought about the com- warming is already having a profound plexities and uncertainties confronting impact on both terrestrial and marine us. Global warming will not lead to uni- ecosystems. form change across the landscape. Some It is interesting to note that the first places will be hotter and drier while species thought to have been driven ex- others may be wetter; in still others the tinct by global climate change was a weather may simply be more variable. snail. Does it matter that one snail goes It may affect plant communities and extinct or that the Uncompahgre fritil- cause seasonal shifts that put species out lary may follow? There has been talk of synchrony with their food sources. lately of taking action to protect some After a fruitless search, I decided to of the species that have been led to the hike the last few hundred feet to the brink of extinction by global warming. ridge to take in the magnificent view. Some scientists have floated the idea Just as I reached the very limit of the of assisted migration (helping species habitat, a familiar sight met my eyes. A move to habitat where they were never faded and battered Uncompahgre fritil- native). For most species this option is lary fluttered across the trail to land on neither feasible nor wise. What we need a rock a few feet away. I sat down next to do is to take heroic efforts as a soci- to the butterfly, noting that its life was ety to curb the impact of global warm- near an end. I then looked up and real- ing. We must find the societal and po- ized that this species really has nowhere litical will to take the actions that are to go as the climate changes. It cannot needed to curb this global threat. live in the rock and ice at the top of the To find out some changes that you peak. I thought about what future gen- can make as an individual, go to www. erations will see when they come up climatecrisis.net/takeaction/whatyou this mountain. It might look the same, cando/index6.html. 4 WINGS Wetland Invertebrates: What Happens When the Pond Is Half-Empty? John H. Matthews In May 2003, I stuffed my car with tween climate change and the aquatic camping and collecting equipment, said macroinvertebrates found in small wet- good-by to my wife, and began a twelve- lands. Given the diversity and abun- hundred-mile drive north from central dance of life they hold, these wetlands Texas. On the front seat next to me sat are both under-studied and beneath the a well-thumbed photocopy of a 1970 radar of the public and policy makers. Ph.D. dissertation about dragonflies, Most small wetlands are ephemeral written by a University of Toronto stu- aquatic habitats (that is, they dry up on dent named Robert Trottier. And the a regular basis), but even “permanent” topmost page had a fuzzy photograph wetlands swing wildly in their annual of a pond in Caledon, Ontario. water volume. Since many fish are in- I was headed to Caledon to begin a tolerant of large shifts in volume, these multi-year study of the relationship be- fish-free habitats are typically rich in in- Common green darners (Anax junius) are found at lakes, ponds, and wetlands across much of North America. Male, photographed in Texas by John C. Abbott. FALL 2007 5 When mating, the male dragonfly grasps the female behind her head, and she curls her abdomen around to accept sperm. Com- mon green darners, photographed in Texas by Giff Beaton. vertebrate diversity. Indeed, the top car- of the water in most small wetlands nivore positions held by fish in larger comes from precipitation. And in recent bodies of water tend to be occupied by decades, the timing, form, and amount dragonfly or beetle larvae in such wet- of precipitation have been changing. lands. But most of these wetlands are Less snow is falling. Globally, precip- viewed as insignificant and marginal itation amounts are increasing and ecosystems, and many countries offer individual precipitation events on av- them little or no protection. In my long erage are becoming more intense. But drive to Caledon I had time to ponder because air temperatures are also gener- the question of just how sensitive these ally warmer, evaporation rates are high- wetlands are to shifts in climate. er. The effect is even stronger in arid Climate change has been generally and semi-arid regions, where, for the viewed through the lens of air temp- most part, precipitation is decreasing erature, a bias reinforced by the term while evaporation rates are rising. As a “global warming.” However, in addition result, many places — even those receiv- to air temperature, many aspects of cli- ing more rain — are actually drier more mate such as wind speed, cloud cover, of the time. To make the matter worse, and relative humidity have been shift- the timing of precipitation is changing ing over the past century. The majority in many areas. As every gardener knows, 6 WINGS the timing of rain matters. Annual in- bodies of water such as rivers and lakes creases in mean precipitation are shift- tend to change volume (or temperature) ing at a monthly or seasonal scale in bi- slowly, even small changes in precip- ologically significant ways. And all of itation regime can radically alter the these changes are likely to intensify in volume of small wetlands, and thus coming decades. the temperature of their water. Less There are two major effects on small water volume means warmer water, wetlands that could come from shifts in since there is a smaller thermal mass.