Tufted puffin reproduction reveals ocean climate variability
Carina Gjerdrum*†, Anne M. J. Valle ́ e‡§, Colleen Cassady St. Clair*¶
Anomalously warm sea-surface temperatures (SSTs) are associated with interannual and decadal variability as well as with long-term climate changes indicative of global warming. Such oscillations could precipitate changes in a variety of oceanic processes to affect marine species worldwide. As global temperatures continue to rise, it will be critically important to be able to predict the effects of such changes on species’ abundance, distribution, and ecological rela- tionships so as to identify vulnerable populations. Off the coast of British Columbia, warm SSTs have persisted through the last two decades. Based on 16 years of reproductive data collected between 1975 and 2002, we show that the extreme variation in reproductive performance exhibited by tufted puffins (Fratercula cirrhata) was related to changes in SST both within and among seasons. Espe- cially warm SSTs corresponded with drastically decreased growth rates and fledging success of puffin nestlings. Puffins may partially compensate for within-season changes associated with SST by adjusting their breeding phenology, yet our data also suggest that they are highly vulnerable to the effects of climate change at this site and may serve as a valuable indicator of biological change in the North Pacific. Further and prolonged increases in ocean tem- perature could make Triangle Island, which contains the largest tufted puffin colony in Canada, unsuitable as a breeding site for this species.
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Ocean climate varies considerably between years and over decades along the Pacific coast of North America (1, 2). Nutrient-poor, warm surface waters characterize both the El Nin ̃o southern oscillation, which occurs every 2–7 years, and the positive phase of the Pacific decadal oscillation, which alternates with the negative phase on a 20- to 30-year cycle (3). The biological response to such large-scale fluctuations in ocean climate are best known in the California current and in the Gulf of Alaska, where studies have documented associated changes in zooplankton biomass (4) and community composition (5, 6), fish population declines (5), geographical range changes in fish and invertebrate species (6, 7), poor reproductive success, range expansions, and contractions, and population declines in a number of breeding marine birds (8–10). Because of the sensi- tivity of marine food webs to the physical changes associated with these oscillations, predicted future changes in global climate (11) are likely to have dramatic effects on marine ecosystems throughout the Pacific.
Such a combined effect of climate and regime changes may already be apparent off the coast of British Columbia, where the northern edge of the up-welling California current meets the southern edge of the down-welling Alaska current (12). In this transitional region, the relative influence of these two domains on local conditions fluctuates seasonally and from year to year, as do oceanic patterns driven by the Aleutian low and North Pacific high atmospheric pressure centers (6). The ecological consequence of ocean climate variability is generally not well understood in this region, but the breeding responses of seabirds may serve as useful indicators of changes to other trophic levels (13–16). For example, warm sea-surface temperatures (SSTs) were associated with low masses of ancient murrelet (Synthlibo- ramphus antiquus) chicks fledging in the Queen Charlotte Is- lands (52.9°N, 131.5°W), presumably via effects on their plank- tivorous and piscivorous prey (17). Farther south, on Triangle Island (50°52