Climate and Demography Dictate the Strength of Predator-Prey Overlap in a Subarctic Marine Ecosystem

Abstract

There is growing evidence that climate and anthropogenic influences on marine ecosystems are largely manifested by changes in species spatial dynamics. However, less is known about how shifts in species distributions might alter predator-prey overlap and the dynamics of prey populations. We developed a general approach to quantify species spatial overlap and identify the biotic and abiotic variables that dictate the strength of overlap. We used this method to test the hypothesis that population abundance and temperature have a synergistic effect on the spatial overlap of arrowtooth flounder (predator) and juvenile Alaska walleye pollock (prey, age-1) in the eastern Bering Sea. Our analyses indicate that (1) flounder abundance and temperature are key variables dictating the strength of flounder and pollock overlap, (2) changes in the magnitude of overlap may be largely driven by density-dependent habitat selection of flounder, and (3) species overlap is negatively correlated to juvenile pollock recruitment when flounder biomass is high. Overall, our findings suggest that continued increases in flounder abundance coupled with the predicted long-term warming of ocean temperatures could have important implications for the predator-prey dynamics of arrowtooth flounder and juvenile pollock. The approach used in this study is valuable for identifying potential consequences of climate variability and exploitation on species spatial dynamics and interactions in many marine ecosystems.

A comparison of fisheries biological reference points estimated from temperature-specific multi-species and single-species climate-enhanced stock assessment models

“…Both of these patterns appear due to cannibalism on ages 1-3 in the multi-species model, which reduces the magnitude of large cohorts and contributes to biomass variability. This is consistent with previous studies; Baily (1989) found that 30% of the diets of older pollock contained juvenile conspecifics, and that cannibalism was higher during daytime diurnal vertical Zador et al, 2011;Hunsicker et al, 2013).…”

“…Diet analyses suggest Pacific cod (Gadus ͳͲ macrocephalus), cannibalistic conspecifics, and arrowtooth flounder (Atheresthes stomias), amongst others, are important predators of pollock populations in the eatern Bering Sea (Livingston 1993;Aydin and Mueter 2007). Arrowtooth flounder have been increasing in recent years, possibly in response to climate conditions that favor their recruitment (e.g., Zador et al, 2011;Hunsicker et al, 2013), yet a combination of low flesh marketability and high bycatch rates of valuable flatfish species limits their annual harvest. This provides an interesting contrast to highly valuable pollock and Pacific cod fisheries, which favor cold conditions projected to decline under future climate scenarios Ianelli et al 2011;Stabeno et al, 2012).…”

Effect of intra‐specific competition, surface chlorophyll and fishing on spatial variation of gadoid's body condition

“…Speciesenvironment interactions are complex, some of them happening at regional scales such as environmental gradients, while others being more sensitive to local variations (Huston 1999). Combining regional with local influence of variables has been proved as a powerful tool to investigate essential ecological processes such as survival, recruitment and trophic interactions (Bartolino et al 2011, Hunsicker et al 2013). Here, we take a step forward and prove the utility of this approach on fish condition, since local influence of the fishing impact and the environmental heterogeneity emerges in the gadoid species analyzed.…”

Evaluating changes in marine communities that provide ecosystem services through comparative assessments of community indicators

“…For ecosystems with a significant trend in the NDES indicator based on the p-value of the Kendall's tau statistic (Table 1), but without a significant relationship in the PPF trend (the eastern Bering Sea, the Gulf of Cadiz, Irish Sea, north Aegean, and U.S. west coast), a signal may be present in the exploited portion of the community that is masked in the overall community. For example, in the eastern Bering Sea, changes in climatic patterns that have influenced summer bottom temperatures have been associated with declines in commercially exploited Alaska pollock (Theragra chalcogramma), and increases in predatory arrowtooth flounder (Atheresthes stomias), for which there is little commercial exploitation (Zador et al, 2011, Hunsicker et al, 2013.…”