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Contemporary ocean warming and freshwater conditions are related to later sea age at maturity in Atlantic salmon spawning in Norwegian rivers
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Atlantic salmon populations are reported to be declining throughout its range, raising major management concerns. Variation in adult fish abundance may be due to variation in survival, growth, and timing of life history decisions. Given the complex life history, utilizing highly divergent habitats, the reasons for declines may be multiple and difficult to disentangle. Using recreational angling data of two sea age groups, one-sea-winter (1SW) and two-sea-winter (2SW) fish originated from the same smolt year class, we show that sea age at maturity of the returns has increased in 59 Norwegian rivers over the cohorts 1991– 2005. By means of linear mixed-effects models we found that the proportion of 1SW fish spawning in Norway has decreased concomitant with the increasing sea surface temperature experienced by the fish in autumn during their first year at sea. Furthermore, the decrease in the proportion of 1SW fish was influenced by freshwater conditions as measured by water discharge during summer months 1 year ahead of seaward migration. These results suggest that part of the variability in age at maturity can be explained by the large-scale changes occurring in the north-eastern Atlantic pelagic food web affecting postsmolt growth, and by differences in river conditions influencing presmolt growth rate and later upstream migration.
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Complexity of Coupled Human and Natural Systems
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Integrated studies of coupled human and natural systems reveal new and complex patterns and processes not evident when studied by social or natural scientists separately. Synthesis of six case studies from around the world shows that couplings between human and natural systems vary across space, time, and organizational units. They also exhibit nonlinear dynamics with thresholds, reciprocal feedback loops, time lags, resilience, heterogeneity, and surprises. Furthermore, past couplings have legacy effects on present conditions and future possibilities.
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Biodiversity and Climate Change
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Efforts to elucidate the effect of climate change on biodiversity with detailed data sets and refined models reach novel conclusions.
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Beyond Predictions: Biodiversity Conservation in a Changing Climate
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Climate change is predicted to become a major threat to biodiversity in the 21st century,
but accurate predictions and effective solutions have proved difficult to formulate. Alarming
predictions have come from a rather narrow methodological base, but a new, integrated science
of climate-change biodiversity assessment is emerging, based on multiple sources and
approaches. Drawing on evidence from paleoecological observations, recent phenological and
microevolutionary responses, experiments, and computational models, we review the insights that
different approaches bring to anticipating and managing the biodiversity consequences of
climate change, including the extent of species’ natural resilience. We introduce a framework
that uses information from different sources to identify vulnerability and to support the design of
conservation responses. Although much of the information reviewed is on species, our framework
and conclusions are also applicable to ecosystems, habitats, ecological communities, and
genetic diversity, whether terrestrial, marine, or fresh water.
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Changes in Wind Pattern Alter Albatross Distribution and Life-History Traits
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Westerly winds in the Southern Ocean have increased in intensity and moved poleward. Using
long-term demographic and foraging records, we show that foraging range in wandering albatrosses
has shifted poleward in conjunction with these changes in wind pattern, while their rates of travel and
flight speeds have increased. Consequently, the duration of foraging trips has decreased, breeding
success has improved, and birds have increased in mass by more than 1 kilogram. These positive
consequences of climate change may be temporary if patterns of wind in the southern westerlies
follow predicted climate change scenarios. This study stresses the importance of foraging performance
as the key link between environmental changes and population processes.
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Defaunation in the Anthropocene
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We live amid a global wave of anthropogenically driven biodiversity loss: species
and population extirpations and, critically, declines in local species abundance.
Particularly, human impacts on animal biodiversity are an under-recognized form of
global environmental change. Among terrestrial vertebrates, 322 species have
become extinct since 1500, and populations of the remaining species show 25%
average decline in abundance. Invertebrate patterns are equally dire: 67% of
monitored populations show 45% mean abundance decline. Such animal declines
will cascade onto ecosystem functioning and human well-being. Much remains unknown
about this “Anthropocene defaunation”; these knowledge gaps hinder our capacity
to predict and limit defaunation impacts. Clearly, however, defaunation is both a
pervasive component of the planet’s sixth mass extinction and also a major driver of
global ecological change
25 JULY 2014 • VOL 345 ISSUE 6195
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All Downhill From Here?
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Biologists say climate change may already be affecting high-mountain ecosystems around the world, where plants and animals adapted to cold, barren conditions now face higher temperatures and a surge of predators and competitors
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Adaptation: Planning for Climate Change and Its Effects on Federal Lands
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National forest managers are charged with tackling the effects of climate change on the natural resources
under their care. The Forest Service National Roadmap for Responding to Climate Change and the Climate
Change Performance Scorecard require managers to make significant progress in addressing climate
change by 2015. To help land managers meet this challenge, Forest Service scientists conducted three case studies on national forests and adjacent national parks and documented a wide range of scientific issues and solutions. They summarized the scientific foundation for climate change adaptation and made the information accessible to land managers by creating a climate change adaptation guidebookand web portal. Case study teams discovered that collaboration among scientists and land managers is crucial to adaptation planning, as are management plans targeted to the particular ecosystem conditions and management priorities of each region. Many current management practices are consistent with climate change
adaptation goals. Because timely implementation is critical, strategies are in development at the national
level to speed the implementation of science-based climate change adaptation processes in national
forests throughout the country.
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Challenges in the conservation, rehabilitation and recovery of native stream salmonid populations: beyond the 2010 Luarca symposium
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– In May 2010, I chaired a session on challenges to salmonid conservation at the international symposium
‘Advances in the population ecology of stream salmonids’ in Luarca, Spain. I suggested that in addition to scientific challenges, a major challenge will be improving the links between ecologists, conservationists and policy makers. Because the Luarca symposium focused mainly on ecological research, little time was explicitly devoted to conservation. My objective in this paper is to further discuss the role of ecological research in informing salmonid conservation. I begin with a brief overview of research highlights from the symposium. I then use selected examples to show that ecological research has already contributed much towards informing salmonid conservation, but that ecologists will always be faced with limitations in their predictive ability. I suggest that conservation will need to move forward regardless of these limitations, and I call attention to some recent efforts wherein ecological research has played a crucial role. I conclude that ecologists should take urgent action to ensure that their results are availableto inform resource managers, conservation organisations and policy makers regarding past losses and present threats to native, locally-adapted salmonid stocks.
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Ecological responses to recent climate change
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There is now ample evidence of the ecological impacts of recent climate change, from polar terrestrial to tropical marine environments. The responses of both flora and fauna span an array of ecosystems and organizational hierarchies, from the species to the community levels. Despite continued uncertainty as to community and ecosystem trajectories under global change, our review exposes a coherent pattern of ecological change across systems. Although we are only at an early stage in the projected trends of global warming, ecological responses to recent climate change are already clearly visible.
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