On the numerous concepts in invasion biology

Source at https://doi.org/10.1007/s10530-005-0710-6.The study of biological invasions has triggered the production of a diversity of concepts. The terminology has, however, often been applied inconsistently and inaccurately. This article lists and assesses the most commonly used terms and concepts in invasion ecology. In each case the most coherent definition and use is suggested

A cross-ecosystem comparison of temporal variability in recruitment of functionally analogous fish stocks

As part of the international MENU collaboration, variability in temporal patterns of recruitment and spawning stock were compared among functionally analogous species from four marine ecosystems including the Gulf of Maine/Georges Bank, the Norwegian/Barents Seas, the eastern Bering Sea and the Gulf of Alaska. Variability was characterized by calculating coefficients of variation for each time series and by representing the time series as anomalies. Patterns of synchrony and asynchrony in recruitment and spawning stock indices were examined among and between ecosystems and related to observed patterns in biophysical properties (e.g. local trophodynamics, local hydrography and large scale climate indices) using a wide range of time series analyses, autocorrelation corrections, autoregressive processes, and multivariate cross-correlation analyses. Of all the commonalities, the relatively similar cross-ecosystem and within-species magnitude of variation was most notable. Of all the differences, the timing of high or low recruitment years across both species and ecosystems was most notable. However, many of the peaks in these indices of recruitment were synchronous across ecosystems for functionally analogous species. Yet the relationships (or lack thereof) between recruitment anomalies and key biophysical properties demonstrated that no one factor consistently caused large recruitment events. Our observations also suggested that there was no routine and common set of factors that influences recruitment; often multiple factors were of similar relative prominence. This work demonstrates that commonalities and synchronies in recruitment fluctuations can be found across geographically very distant ecosystems, but biophysical causes of the fluctuations are difficult to partition. Keywords: Ecosystem, recruitment, trophodynamics, variation

A comparison of community and trophic structure in five marine ecosystems based on energy budgets and system metrics

As part of the international MENU collaboration, energy budget models for five marine ecosystems were compared to identify differences and similarities in trophic and community characteristics across ecosystems. We examined the Gulf of Maine and Georges Bank in the Northwest Atlantic Ocean, the combined Norwegian/Barents Seas in the Northeast Atlantic Ocean, and the eastern Bering Sea and the Gulf of Alaska in the Northeast Pacific Ocean. Comparable energy budgets were constructed for each ecosystem by aggregating information for similar species groups into consistent functional groups across all five ecosystems. Several ecosystem metrics (including functional group production, consumption, and biomass ratios, ABC curves, cumulative biomass, food web macrodescriptors, and network metrics) were examined across the ecosystems. The comparative approach clearly identified data gaps for each ecosystem, an important outcome of this work. Commonalities across the ecosystems included overall high primary production and energy flow at low trophic levels, high production and consumption by carnivorous zooplankton, and similar proportions of apex predator to lower trophic level biomass. Major differences included distinct biomass ratios of pelagic to demersal fish, ranging from highest in the Norwegian/Barents ecosystem to lowest in the Alaskan systems, and notable gradients in primary production per unit area, highest in the Alaskan and Georges Bank/Gulf of Maine ecosystems, and lowest in the Norwegian ecosystems. While comparing a disparate group of organisms across a wide range of marine ecosystems is challenging, this work demonstrates that standardized metrics both elucidate properties common to marine ecosystems and identify key distinctions for fishery management

Ecosystem effects of red king crab invasion. A modelling approach using Ecopath with Ecosim

Barents Sea ecosystem is limited. Due to the information available on benthos the Ecopath model of Sørfjord, Northern Norway, was used to investigate possible trophic changes with introduction of king crab to the model. A literature study of the king crab was conducted to find information on diet, mortality, consumption rate and other life history parameters required by the model. A short introduction to biological invasions was also included. The Ecopath with Ecosim software was used as a modelling tool to investigate factors allowing for growth of king crab as well as potentially controlling their biomass. Possible food-web effects of king crab invasion on the Sørfjord ecosystem was also investigated. Knowledge gaps identified through the exercise and management implications were discussed. A biomass of 1.2 t km-2 small and 2.8 t km-2 large king crabs was introduced to the Sørfjord model. The modelling exercise indicated that a resource opportunity, in the form of benthic production, could allow for growth of the king crab in Sørfjord. Mammals could have a negative impact on large king crab abundance through predation, while fish predation is expected to have minor effects on king crab biomass. King crabs are expected to have a negative effect on the benthic community through predation, but limited impact on the pelagic community. King crab abundance could be controlled by fishing large king crabs. A change in fishing of other commercial fish species is not expected to have an impact on king crab biomass. Knowledge gaps identified from this exercise includes population structure, biology and food preference of king crab. Production and interactions within the native benthic community should also be investigated further to understand possible impacts of king crab invasion

Management of the alien invasive red king crab Integrating natural and social science perspectives

The red king crab (Paralithodes camtschaticus) is a highly valuable resource that also represents a potential threat since it is an alien invasive species in the Barents Sea ecosystem. This thesis explores the use of different interdisciplinary frameworks to analyse how ecological, social and economic concerns could be accounted for in deciding on how the king crab should be managed in the Norwegian part of the Barents Sea. Clarification of terminology used in invasion biology and systematisation of ecological information in order to establish the ecological knowledge base for management forms the basis for further analysis. Bio-economic modelling and discourse analysis are used to explore how uncertainty and the range of services the ecosystem provides can be incorporated in management. Finally the use of ecosystem service frameworks to integrate ecosystem and social science research in ecosystem based management is discussed. The ecological review revealed numerous knowledge gaps in our understanding of how the king crab interacts with native biota. It also identified negative impacts on benthic ecosystems that provide supporting services, and on provisioning services through predation on eggs of commercial fish. Bio-economic analysis illustrated the need to identify the correct relationship between crab stock size and ecosystem damage. It also showed that optimal harvest of king crab cannot be reconciled with the Barents Sea management goal of securing the ecosystem structure. The discourse analysis showed that people recognise both positive and negative impacts of the crab on supporting, provisioning and cultural services. In addition the impacts on ecosystem services we do not have the knowledge to value today, or option values, were important in forming people’s perception on how the crab should be managed. This thesis demonstrates that while the natural sciences have a clear role to play in establishing the ecological knowledge base, uncertainty and the need to account for stakeholder concerns calls for integration of social science research in the management process. Ecosystem service frameworks can be useful tools for identification, integration and evaluation of such information

Ecosystem effects of red king crab invasion. A modelling approach using Ecopath with Ecosim

Barents Sea ecosystem is limited. Due to the information available on benthos the Ecopath model of Sørfjord, Northern Norway, was used to investigate possible trophic changes with introduction of king crab to the model. A literature study of the king crab was conducted to find information on diet, mortality, consumption rate and other life history parameters required by the model. A short introduction to biological invasions was also included. The Ecopath with Ecosim software was used as a modelling tool to investigate factors allowing for growth of king crab as well as potentially controlling their biomass. Possible food-web effects of king crab invasion on the Sørfjord ecosystem was also investigated. Knowledge gaps identified through the exercise and management implications were discussed. A biomass of 1.2 t km-2 small and 2.8 t km-2 large king crabs was introduced to the Sørfjord model. The modelling exercise indicated that a resource opportunity, in the form of benthic production, could allow for growth of the king crab in Sørfjord. Mammals could have a negative impact on large king crab abundance through predation, while fish predation is expected to have minor effects on king crab biomass. King crabs are expected to have a negative effect on the benthic community through predation, but limited impact on the pelagic community. King crab abundance could be controlled by fishing large king crabs. A change in fishing of other commercial fish species is not expected to have an impact on king crab biomass. Knowledge gaps identified from this exercise includes population structure, biology and food preference of king crab. Production and interactions within the native benthic community should also be investigated further to understand possible impacts of king crab invasion

Bio-Economic Modelling of the Red King Crab Invasion in the Barents Sea

The red king crab (Paralithodes camtschaticus) is an alien invasive species in the Barents Sea representing a value as well as a potential pest. A bio-economic model is applied analysing the costs that traditional fisheries incur as a result of the king crab invasion, as well as the income from king crab harvest. Since the impact of the king crab on the native species is not known, bycatch costs in traditional fisheries were used as a proxy for cost related to the invasion. The model suggests that the king crab stock should be reduced in order to optimize the profit of the total fishery. The model is robust to changes in input parameters. Large uncertainties related to the costs of the king crab invasion, however, illustrate the need to improve our knowledge with regards to the effect of the king crab on the traditional fishery as well as the native ecosystem

The value of familiarity: Effects of knowledge and objective signals on willingness to pay for a public good

We design and conduct a field experiment in which treated subjects receive a precise and objective signal regarding their knowledge about a public good before estimating their WTP for it. We find that the causal effect of objective signals about the accuracy of a subject׳s knowledge for a public good can dramatically affect their valuation for it: treatment caused a significant increase of $85–$129 in WTP for well-informed individuals. We find no such effect for less informed subjects. Our results imply that WTP estimates for public goods are not only a function of true information states of the respondents but beliefs about those information states