Article

Ecological thresholds and regime shifts: approaches to identification.

Department of Biology, University of Oslo, P.O. Box 1066, Blindern, N0316 Oslo, Norway.
Trends in Ecology & Evolution (Impact Factor: 15.35). 11/2008; 24(1):49-57. DOI: 10.1016/j.tree.2008.07.014
Source: PubMed

ABSTRACT There is an apparent gap between the prominence of present theoretical frameworks involving ecological thresholds and regime shifts, and the paucity of efforts to conduct simple tests and quantitative inferences on the actual appearance of such phenomena in ecological data. A wide range of statistical methods and analytical techniques are now available that render these questions tractable, some of them even dating back half a century. Yet, their application has been sparse and confined within a narrow subset of cases of ecological regime shifts. Our objective is to raise awareness on the range of techniques available, and to their principles and limitations, to promote a more operational approach to the identification of ecological thresholds and regime shifts.

Download full-text

Full-text

Available from: Jacob Carstensen, Jul 05, 2015
1 Follower
 · 
119 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Motivational changes in animals are likely to be detectable retrospectively through observed changes in behavior. Breeding represents one of the strongest motivational states in mammals, and its timing is often tied to a seasonally optimal suite of environmental and physical conditions. While seasonal changes in behavior may be directly observable in some species, for others that breed cryptically or in difficult to access areas, detecting behavioral changes may only be feasible using data collected remotely. Herein, we explore whether behavioral changes can be used to infer motivational state for a wild, free-and wide-ranging high arctic marine mammal , adult male Atlantic walruses (Odobenus rosmarus rosmarus). Using satellite-relayed location and dive data from 23 adult male walruses instrumented in the Svalbard Archipelago, we identify seasonal movement to discrete geographic regions deep into winter pack ice. Adult male walrus diving behavior underwent marked seasonal movements between geographical areas that coincided with changes in light regime. At offshore wintering sites adult males (n = 4) shifted from a summer pattern of deep, long benthic dives to much shallower diving. Some males performed similar shallow, winter dive behavior at coastal locations (n = 12) suggesting that breeding might also occur around the coast of Svalbard. However, interpretation of behavioral changes of these coastal individuals was challenging. The presumed breeding sites at the winter offshore locations were situated in areas where polynyas are known to occur, making them a predictable resource even if they are located deep inside the winter pack-ice. We demonstrate that remotely collected behavioral data can be used to identify seasonally explicit changes in the behavior of cryptic species.
    Marine Mammal Science 04/2015; DOI:10.1111/mms.12224 · 1.82 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Our ability to adapt to climate change is not boundless, and previous modeling efforts show that future policy decisions about climate change are affected when adaptation limits are exceeded. Adaptation limits are delineated by capacity thresholds, after which climate damages begin to overwhelm the adaptation response and net adaptation goes negative. The levels of such thresholds depend on the complex interaction of different environmental (climatic and ecological) and human response (technological and societal) systems. In this paper, the interactions among these sub-systems are explored and four novel archetypical climate damage and adaptation response systems are developed. These damage–response systems can be described by the level of their adaptation limits thresholds, the pathways of adaptation capacity degradation and failure, and the recoverability or permanence of such climate losses once the adaptation limits have been surpassed. Policy options upon reaching the limits to adaptation include investment in more of the same technology, implementation of new and more effective adaptation, or transformational adaptation that allows the damage–response system to become more resilient. Attention is drawn to the need for greater understanding of the uncertainties of adaptation limits, how to raise the effective capacities and lifetime ranges of adaptation (and thus delay adaptation failure), and what policy options exist when adaptation limits are breached.
    Environmental Science & Policy 03/2015; 50:214-224. DOI:10.1016/j.envsci.2015.03.003 · 3.51 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Freshwaters are being transformed by multiple environmental drivers, creating uncertainty about future conditions. One way of coping with uncertainty is to manage for resilience to unanticipated events while facilitating learning through adaptive management. We outline the application of these strategies to freshwater recreational fisheries management using a case study in Wisconsin, USA, where black bass (Micropterus spp.) populations are increasing, while Walleye (Sander vitreus) populations are decreasing. Managing for heterogeneity in functional groups (e.g., age classes and prey species of sport fishes), fishery objectives, and regulations can increase resilience, although heterogeneity must be balanced with replication to facilitate learning. Monitoring designed to evaluate management objectives and inform about critical uncertainties, when combined with heterogeneity, creates opportunities for adaptive management, another critical resilience strategy. Although barriers exist to implementing resilience strategies, management designed to accommodate uncertainty and illuminate its consequences is needed to maintain critical fisheries in a rapidly changing world.
    Fisheries 02/2015; 40(2). DOI:10.1080/03632415.2014.996804 · 2.32 Impact Factor