Day-to-day variation in sea-surface temperature reduces sooty tern Sterna fuscata foraging success on the Great Barrier Reef, Australia

Abstract

Many seabird species threatened by global climate change are found mainly or exclusively in tropical regions. A shortage of long-term data linking climatic variation, oceanography and tropical seabird reproductive biology at both within- and between-season temporal scales means that the potential impact of climate change on these species is largely unknown. The sooty tern Sterna fuscata, an almost ubiquitous tropical seabird, has been declining on the Great Barrier Reef (GBR), Australia, over the last 3 decades. We examined the relationship between sooty tern foraging success and sea-surface temperature (SST) at Michaelmas Cay over 2 consecutive breeding seasons. Consistent patterns were observed with significant negative relationships between day-to-day variation in SST and both the amount of food fed to chicks and the feeding frequency during the latter two-thirds of each breeding season. At the beginning of each breeding cycle, rapid changes in foraging success highlighted that other within-season mechanisms also influence sooty tern reproductive potential. Our results suggest a previously undescribed spatial and temporal link between SST and sooty tern reproduction. Combined with previous findings for the southern GBR, this suggests that SST variation can influence the foraging success of multiple tropical seabird species at a reef-wide scale and implies a significant negative effect of forecasted climatic changes on seabirds breeding on the GBR. © Inter-Research 2007.