Climate influences a population through a variety of processes, including reproduction, growth, migration patterns and phenology. Climate may operate either directly through metabolic and reproductive processes or indirectly through prey, predators, and competitors. One mechanism that may be particularly important, and which is the focus of this review, is the role of climate in affecting the reproductive success of a predator through its effect on the relative timing of food requirement and food availability during early life stages. This principle -the match or mismatch of predators' requirement with resource availability -originated in the marine literature, where it initially referred to how growth and survival of fish larvae (predator) depends on this production being synchronous with that of their main food items, i.e. early stage zooplankton (prey). Here we review how the match/mismatch hypothesis (MMH) is used to describe climate effects on ecological patterns and processes in both marine and terrestrial systems. In addition to studying match/mismatch sensu stricto, we expand on it to include effects of overall production level and the spatial aspect. Possible impacts of climate change on match/mismatch are examined in the context of one of the most apparent effects of global warming: an advancement of spring phenology. As a consequence of different species reacting dissimilarly, even minor changes in climate may invoke non-linear responses unbalancing established patterns of synchrony. All components of a food chain cannot be expected to shift their phenology at the same rate, and thus are unlikely to remain synchronous.

Climatic changes are disrupting otherwise tight trophic interactions between predator and prey. Most of the earlier studies have primarily focused on the temporal dimension of the relationship in the framework of the match-mismatch hypothesis. This hypothesis predicts that predator's recruitment will be high if the peak of the prey availability temporally matches the most energy-demanding period of the predators breeding phenology. However, the match-mismatch hypothesis ignores the level of food abundance while this can compensate small mismatches. Using a novel time-series model explicitly quantifying both the timing and the abundance component for trophic relationships, we here show that timing and abundance of food affect recruitment differently in a marine (cod/zooplankton), a marine-terrestrial (puffin/herring) and a terrestrial (sheep/vegetation) ecosystem. The quantification of the combined effect of abundance and timing of prey on predator dynamics enables us to come closer to the mechanisms by which environment variability may affect ecological systems.

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In 2007, the Intergovernmental Panel on Climate Change highlighted an urgent need to assess the responses of marine ecosystems to climate change. Because they lie in a high-latitude region, the Southern Ocean ecosystems are expected to be strongly affected by global warming. Using top predators of this highly productive ocean (such as penguins) as integrative indicators may help us assess the impacts of climate change on marine ecosystems. Yet most available information on penguin population dynamics is based on the controversial use of flipper banding. Although some reports have found the effects of flipper bands to be deleterious, some short-term (one-year) studies have concluded otherwise, resulting in the continuation of extensive banding schemes and the use of data sets thus collected to predict climate impact on natural populations. Here we show that banding of free-ranging king penguins (Aptenodytes patagonicus) impairs both survival and reproduction, ultimately affecting population growth rate. Over the course of a 10-year longitudinal study, banded birds produced 41% [corrected] fewer chicks and had a survival rate 16 percentage points [corrected] lower than non-banded birds, demonstrating a massive long-term impact of banding and thus refuting the assumption that birds will ultimately adapt to being banded. Indeed, banded birds still arrived later for breeding at the study site and had longer foraging trips even after 10 years. One of our major findings is that responses of flipper-banded penguins to climate variability (that is, changes in sea surface temperature and in the Southern Oscillation index) differ from those of non-banded birds. We show that only long-term investigations may allow an evaluation of the impact of flipper bands and that every major life-history trait can be affected, calling into question the banding schemes still going on. In addition, our understanding of the effects of climate change on marine ecosystems based on flipper-band data should be reconsidered.

Current evidence of phenological responses to recent climate change is substantially biased towards northern hemisphere temperate regions. Given regional differences in climate change, shifts in phenology will not be uniform across the globe, and conclusions drawn from temperate systems in the northern hemisphere might not be applicable to other regions on the planet. We conduct the largest meta-analysis to date of phenological drivers and trends among southern hemisphere species, assessing 1208 long-term datasets from 89 studies on 347 species. Data were mostly from Australasia (Australia and New Zealand), South America and the Antarctic/subantarctic, and focused primarily on plants and birds. This meta-analysis shows an advance in the timing of spring events (with a strong Australian data bias), although substantial differences in trends were apparent among taxonomic groups and regions. When only statistically significant trends were considered, 82% of terrestrial datasets and 42% of marine datasets demonstrated an advance in phenology. Temperature was most frequently identified as the primary driver of phenological changes; however, in many studies it was the only climate variable considered. When precipitation was examined, it often played a key role but, in contrast with temperature, the direction of phenological shifts in response to precipitation variation was difficult to predict a priori. We discuss how phenological information can inform the adaptive capacity of species, their resilience, and constraints on autonomous adaptation. We also highlight serious weaknesses in past and current data collection and analyses at large regional scales (with very few studies in the tropics or from Africa) and dramatic taxonomic biases. If accurate predictions regarding the general effects of climate change on the biology of organisms are to be made, data collection policies focussing on targeting data-deficient regions and taxa need to be financially and logistically supported.

Co-occurrence in food requirements of offspring and food availability is a key factor determining breeding success. Prey availability is typically dependent on environmental conditions that are different from those influencing the predator's decision regarding whether or not to initiate breeding, and is not always optimal at the peak of reproduction requirements. We investigated this relationship to understand better what determines the fledging success of the Atlantic puffin (Fratercula arctica). Colony data from Røst (northern Norway) covering a period of 27 years were analysed with parallel data on sea temperature and the size and abundance of the puffins' main prey (the Norwegian spring-spawning herring, Clupea harengus). By fitting statistical models to the fledging success, we found that one effect of climate on this population of Atlantic puffins is indirect and mediated by sea temperature affecting the availability of first-year herring. The best model also demonstrates that the breeding success of the Røst puffins may be quantitatively predicted from the size of first-year herring and sea temperature.

Accumulating evidence shows that environmental fluctuations and exploitation jointly affect marine fish populations, and understanding their interaction is a key issue for fisheries ecology. In particular, it has been proposed that age truncation induced by fisheries exploitation may increase the population's sensitivity to climate. In this study, we use unique long-term abundance data for the Northeast Arctic stock of cod (Gadus morhua) and the Norwegian SpringSpawning stock of herring (Clupea harengus), which we analyze using techniques based on age-structured population matrices. After identifying time periods with different age distributions in the spawning stock, we use linear models to quantify the relative effect of exploitation and temperature on the population growth rates. For the two populations, age truncation was found to be associated with an increasing importance of temperature and a relatively decreasing importance of exploitation, while the population growth rate became increasingly sensitive to recruitment variations. The results suggested that the removal of older age classes reduced the buffering capacity of the population, thereby making the population growth rate more dependent on recruitment than adult survival and increasing the effect of environmental fluctuations. Age structure appeared as a key characteristic that can affect the response of fish stocks to climate variations and its consequences may be of key importance for conservation and management.