Monitoring marine populations and communities : methods dealing with imperfect detectability

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Monitoring marine populations and communities: methods dealing with imperfect detectability

Effective monitoring of populations and communities is a prerequisite for ecosystem-based management of marine areas. However, monitoring programs often neglect important sources of error and thus can lead to biased estimations, spurious conclusions, and false management actions. One such source of error is imperfect detectability, i.e. inability of investigators to detect all individuals or all species in a surveyed area. Although there has been great effort to develop monitoring methods that account for imperfect detectability, the application of such methods in the marine environment is not as apparent. Plot sampling is by far the most commonly applied method for biological monitoring in the marine environment, yet it largely ignores detectability issues. However, distance sampling, mark-recapture methods, repeated presence/absence surveys for occupancy estimation, and removal methods, are approaches developed that do estimate detection probabilities and provide unbiased estimations of state variables. Herein, these methods and the relevant tools for their application in studies on marine populations and communities are critically reviewed, aiming to assist marine biologists and managers to understand the limitations and pitfalls associated with some approaches and to select the best available methods for their monitoring needs.JRC.H.1-Water Resource

Monitoring marine populations and communities: methods dealing with imperfect detectability

Effective monitoring of populations and communities is a prerequisite for ecosystembased management of marine areas. However, monitoring programs often neglect important sources of error and thus can lead to biased estimates, spurious conclusions and false management actions. One such source of error is ‘imperfect detectability’, i.e. the inability of investigators to detect all individuals or all species in a surveyed area. Although there has been great effort to develop monitoring methods that account for imperfect detectability, the application of such methods in the marine environment is not as apparent as in other systems. Plot sampling is by far the most commonly applied method for biological monitoring in the marine environment, yet it largely ignores detectability issues. However, distance sampling, mark-recapture methods, repeated presence-absence surveys for occupancy estimation, and removal methods do estimate detection probabilities and provide unbiased estimates of state variables. We review these methods and the relevant tools for their application in studies on marine populations and communities, with the aim of assisting marine biologists and managers to understand the limitations and pitfalls associated with some approaches and to select the best available methods for their monitoring needs

Monitoring and evaluation of spatially managed areas: A generic framework for implementation of ecosystem based marine management and its application

This study introduces a framework for the monitoring and evaluation of spatially managed areas (SMAs), which is currently being tested by nine European case studies. The framework provides guidance on the selection, mapping, and assessment of ecosystem components and human pressures, the evaluation of management effectiveness and potential adaptations to management. Moreover, it provides a structured approach with advice on spatially explicit tools for practical tasks like the assessment of cumulative impacts of human pressures or pressure-state relationships. The case studies revealed emerging challenges, such as the lack of operational objectives within SMAs, particularly for transnational cases, data access, and stakeholder involvement. Furthermore, the emerging challenges of integrating the framework assessment using scientific information with a structured governance research analysis based mainly on qualitative information are addressed. The lessons learned will provide a better insight into the full range of methods and approaches required to support the implementation of the ecosystem approach to marine spatial management in Europe and elsewhere

Ecosystem-based marine spatial management: Review of concepts, policies, tools, and critical issues

Conventional sectoral management and piecemeal governance are considered less and less appropriate in pursuit of sustainable development. Ecosystem based marine spatial management (EB-MSM) is an approach that recognizes the full array of interactions within an ecosystem, including human uses, rather than considering single issues, species, or ecosystem services in isolation. Marine spatial planning and ocean zoning are emerging concepts that can support EB-MSM. EB-MSM is driven by high-level goals that managers aim to achieve through the implementation of measures. High-level goals and objectives need to be translated into more operational objectives before specific targets, limits and measures can be elaborated. Monitoring, evaluation and adaptation are necessary to ensure that marine management measures are both effective and efficient. Solid monitoring frameworks are the foundation of adaptive management, as they provide the necessary information to evaluate performance and the effectiveness of management actions. Marine protected areas (MPAs) - possibly set up in networks - constitute a key component in EB-MSM policies and practises and have been applied as a cornerstone in conservation of marine biodiversity, management of fish populations, development of coastal tourism, etc. Moreover, MPA experiences have provided methods and concepts (such as zoning) to a wider EB-MSM context. The assignment of values to biophysical features of the marine environment allows the direct assessment of related management choices and may assist EB-MSM. A range of monetary valuation techniques have been proposed to reduce attributes of goods and services to a single metric. However, in the marine environment such an approach is often over simplistic, and thus less reductive techniques may be necessary. Rather than producing a single metric, the results of non-monetary assessments guide policy allowing weight to be given as necessary to potential areas of conflict and consensus. Strategies to take into account climate change effects and geohazard risks in EB-MSM have been applied or proposed worldwide. EB-MSM regimes must be alert to such risks and flexible to account for changes