Intra-seasonal variation in zooplankton availability, chick diet and breeding performance of a high Arctic planktivorous seabird

Abstract

Different phenological responses to climate changes by species representing preys and predators may lead to mismatch between functionally dependent components of an ecosystem, with important effects on its structure and functioning. Here, we investigate withinseason variation in zooplankton availability, chick diet composition and breeding performance of a small planktivorous seabird, the little auk (Alle alle) in two large colonies in Hornsund and Magdalenefjorden, Spitsbergen, differing in synchrony of breeding (11-day vs. 22-day hatching period, respectively). Assuming similar zooplankton phenology and existing differences in duration of the little auk breeding period, we expected lower availability of the preferred food in the less synchronized colony in Magdalenefjorden and in consequence a negative effect on nestling body mass and survival. We found that in both colonies Calanus glacialis (copepodite stage CV) was the most important prey item in the chick diet making up 68-87 % of the biomass and energy of all prey items. The only exception was the end of the chick-rearing period in Magdalenefjorden, when contribution of this prey item was significantly lower (24-26 %). Thus, late breeders in Magdalenefjorden were apparently mismatched regarding C. glacialis CV availability. However, the hatching date did not affect birds fitness (reproductive output and chick pre-fledging mass) significantly. Results of our study indicate that little auks breeding on Spitsbergen can respond to a wide range of environmental conditions and prey availabilities through the plasticity of their foraging behaviour, which may help them to maintain their optimum fitness level in changing and unpredictable environments.

Habitat foraging niche of a High Arctic zooplanktivorous seabird in a changing environment

“…However, fledging success in Isfjorden (62–97%), the ‘high-Arctic’ colony characterized by a higher SST in the foraging grounds and without easy access to alternative foraging grounds, was generally lower than in Magdalenefjorden (range 91–100%) 58 . Higher success recorded in the latter colony, if not affected by a lower predation rate (it has not been studied), may have been attributed to possibility of compensation of local suboptimal conditions by foraging in MIZ 65 . Moreover, buffering the suboptimal foraging conditions through behavioural plasticity may have long-term consequences for little auks.…”

Dynamics of Calanus Copepodite Structure during Little Auks’ Breeding Seasons in Two Different Svalbard Locations

“…The phenology of Calanus is a critical factor for little auks reproduction success during their breeding season, as was shown recently in a spatial perspective study in Greenland [44] and in time perspective study in Svalbard waters [64]. Therefore it is now of vital importance to study the match in time and space between the availability of older life stages of Calanus and little auks, because as was shown by this study, the development rate and the age structure of Calanus may differ significantly depending on the region, water temperature and time in the season.…”

“…Therefore it is now of vital importance to study the match in time and space between the availability of older life stages of Calanus and little auks, because as was shown by this study, the development rate and the age structure of Calanus may differ significantly depending on the region, water temperature and time in the season. The issue is alarming not only because temperature warming has been shown to accelerate development of Calanus [65], but also because the altered phenology of many species is becoming an increasingly important problem for trophic interactions [31,64,66] and thus entire food webs. To date, disturbance in interactions between predators and prey (match/mismatch) have been observed in many groups of organisms, e.g., between fish and plankton [67,68], insects and plants [69], birds and insects [70][71][72] shorebirds and arthropods [73] or seabirds and zooplankton [33,74,75].…”

Assortative mating patterns of multiple phenotypic traits in a long‐lived seabird

“…If conditions in foraging areas are unfavourable, both parents need to increase their efforts to ensure that a given breeding attempt is successful (Jakubas et al . ). As increased parental efforts in such stressful situations are mediated by changes in corticosterone levels (Harding et al .…”