Search results for "Regime shift"
showing 10 items of 17 documents
Managing for resilience: an information theory-based approach to assessing ecosystems
2016
Ecosystems are complex and multivariate; hence, methods to assess the dynamics of ecosystems should have the capacity to evaluate multiple indicators simultaneously. Most research on identifying leading indicators of regime shifts has focused on univariate methods and simple models which have limited utility when evaluating real ecosystems, particularly because drivers are often unknown. We discuss some common univariate and multivariate approaches for detecting critical transitions in ecosystems and demonstrate their capabilities via case studies. Synthesis and applications. We illustrate the utility of an information theory-based index for assessing ecosystem dynamics. Trends in this inde…
Temporary Allee effects among non‐stationary recruitment dynamics in depleted gadid and flatfish populations
2021
Many considerably declined fish populations have not fully recovered despite reductions in fishing pressure. One of the possible causes of impaired recovery is the (demographic) Allee effect. To investigate whether low-abundance recruitment dynamics can switch between compensation and depensation, the latter implying the presence of the Allee effect, we analysed the stock–recruitment time series of 17 depleted cod-type and flatfish populations using a Bayesian change point model. The recruitment dynamics were represented with the sigmoidal Beverton–Holt and the Saila–Lorda stock–recruitment models, allowing the parameters of the models to shift at a priori unknown change points. Our synthes…
Environmental drivers and abrupt changes of phytoplankton community in temperate lake Lielais Svētiņu, Eastern Latvia, over the last Post-Glacial per…
2021
Understanding the long-term dynamics of ecological communities on the centuries-to-millennia scale is important for explaining the emergence of present-day biodiversity patterns and for predicting possible future scenarios. Fossil pigments and ancient DNA present in various sedimentary deposits can be analysed to study long-term changes in ecological communities. We analysed recent compilations of data, including fossil pigments, microfossils, and molecular inventories from the sedimentary archives, to understand the impact of gradual versus abrupt climate changes on the ecosystem status of a regional model lake over the last ~14.5 kyr. Such long and complete paleo-archives are scarce in No…
Atlantic salmon survival at sea: temporal changes that lack regional synchrony
2022
Spatial and temporal synchrony in abundance or survival trends can be indicative of whether populations are affected by common environmental drivers. In Atlantic salmon (Salmo salar L.), return rates to natal rivers have generally been assumed to be affected primarily by shared oceanic conditions, leading to spatially synchronous trends in mortality. Here, we investigated the existence of parallel trends in salmon sea survival, using data on migrating smolts and returning adults from seven Canadian populations presumed to share feeding grounds. We analysed sea survival, using a Bayesian change-point model capable of detecting non-stationarity in time series data. Our results indicate that w…
Social–ecological connections across land, water, and sea demand a reprioritization of environmental management
2022
International audience; Despite many sectors of society striving for sustainability in environmental management, humans often fail to identify and act on the connections and processes responsible for social-ecological tipping points. Part of the problem is the fracturing of environmental management and social-ecological research into ecosystem domains (land, freshwater, and sea), each with different scales and resolution of data acquisition and distinct management approaches. We present a perspective on the social-ecological connections across ecosystem domains that emphasize the need for management reprioritization to effectively connect these domains. We identify critical nexus points rel…
Complementary methods assessing short and long-term prey of a marine top predator ‒ Application to the grey seal-fishery conflict in the Baltic Sea.
2019
The growing grey seal (Halichoerus grypus) population in the Baltic Sea has created conflicts with local fisheries, comparable to similar emerging problems worldwide. Adequate information on the foraging habits is a requirement for responsible management of the seal population. We investigated the applicability of available dietary assessment methods by comparing morphological analysis and DNA metabarcoding of gut contents (short-term diet; n = 129/125 seals, respectively), and tissue chemical markers i.e. fatty acid (FA) profiles of blubber and stable isotopes (SIs) of liver and muscle (mid- or long-term diet; n = 108 seals for the FA and SI markers). The methods provided complementary inf…
Depletion of coastal predatory fish sub-stocks coincided with the largest sea urchin grazing event observed in the NE Atlantic
2020
AbstractIn this contribution, we propose fishery driven predator release as the cause for the largest grazing event ever observed in the NE Atlantic. Based on the evolving appreciation of limits to population connectivity, published and previously unpublished data, we discuss whether overfishing caused a grazer bloom of the sea urchin (Strongylocentrotus droebachiensis) resulting in overgrazing of more than 2000 km2 kelp (Laminaria hyperborea) forest along Norwegian and Russian coasts during the 1970 s. We show that coastal fisheries likely depleted predatory coastal fish stocks through modernization of fishing methods and fleet. These fish were important predators on urchins and the reduct…
Macroeconomic Modelling in EMU: How Relevant is the Change in Regime?
2007
We analyse the likely effects of changes in the monetary and financial regimes of EMU countries on the dynamics of output and inflation. In particular, we evaluate the impact of the regime shift on the forecasting performance of reduced-form models. Data for both the pre-EMU and the EMU regimes are generated by a relatively standard open-economy-DSGE model with sticky prices and wages and restricted access to financial markets for some individuals. We find that the effects of the shift in the monetary regime on the processes followed by macroeconomic variables depend on the nature of the shocks hitting the economy. For plausible shocks distributions the reduction in the accuracy of VAR-base…
Regime shifts and alternative stable states in intertidal rocky habitats: State of the art and new trends of research
2018
Abstract The existence of regime shifts and alternative stable states in ecosystems is well known and has very large effects on their structure and dynamics. Since shifts between alternative stable states have significant implications for the ecosystems conservation, their prevention should be an aim of primary interest, and for this reason a particular attention has been paid to their study. Regarding marine ecosystems, rocky intertidal habitats, in particular, represent an ideal system for the study of alternative stable states because of their characteristics: they exhibit strong environmental gradients, are easy to manipulate, and most of the inhabiting species grow rapidly. Given the s…
Estimating the substitutability between private and public consumption: the case of Spain, 1960–2003
2005
This paper examines the relationship between private and public consumption using Spanish data over the period 1960–2003, using a two-good permanent-income model. We extend previous analysis addressing the question of whether this relationship is stable over time, or exhibits a structural break allowing the instability to occur at an unknown point in time. Our empirical results indicated the existence of a long-run relationship between private and public consumption. We also detect a structural change of regime shift in the cointegration regression around the time of 1973–74. Finally, the estimated intratemporal and intertemporal elasticities of substitution between the two types of expendi…