discussion
In our research question we are asking for assessment methods to evaluate the effects of multiple stressors impacting the marine ecosystem in the anthropocene. This research question was based on the hypotheses that various assessment methods for single stressors exist, but there are not many approaches for multiple stressors assessments. Emphasizing the need for multivariate assessment methods to get a comprehensive insight how multiple stressors can interact and affect the marine ecosystem, we started our literature review on setting a baseline for these assessments. Defining what actually is understood by ecosystem health and describing how stressors can interct, we listed tools and indicators which can be used in the assessment process to identify stressors and their potential interaction. Furthermore we established criteria that an ideal assessment method for multiple stressors should fulfill in order to be effectiv and comprehensive.
Moving on from this baseline we looked at various proposed assessment methods and case studies of marine health to get an overview of available assessment methods, including univariate, as well as multivariate methods. By this literature review, we were able to detect and seperate several, individual assessment methods, some more commonly used and recogniezed than other, more novel concepts. Based on the earlier established criteria we evaluated these methods, taking into consideration the demands, availabilty of tools and background information that we aquired in the theory section, to detect the strength, weaknesses and possible pitfalls of each method. Hence we came to the conclusion that a single method will not cover all the established methods sufficiently and consequently a combination of methods is required to establish a holistic assessment method for multiple stressors. This conjuction of single methods, termed meta-methods, have as a matter of course already been taken into consideration in several studies. Analyzing and comparing th different steps of proposed meta-methods, we searched for similarities and generally consistent steps, which can be found in all meta-method approaches of multiple stressors assessments. As a result we created a merged meta-method including our own considerations and improvements. This meta-method, including nine different steps, is the attempt to find a holistic and extensive assessment methods for multiple stressors in the anthropocene.
NEEEWW
In our research question, we seek assessment methods to evaluate the effects of multiple stressors impacting the marine ecosystem in the anthropocene. This research question was based on the hypotheses that various assessment methods for single stressors exist, but there are few approaches for multiple stressors assessments. Emphasizing the need for integrative ecosystem based assessment methods to get a comprehensive insight into how multiple stressors can interact and affect the marine ecosystem, we started our literature review on setting a baseline for these assessments, especially in the changing environmental conditions of the Anthropocene; thus defining what actually is understood by ecosystem health and degradative deviation from this state and describing how stressors can interact. We listed tools and indicators which can be used in the assessment process to identify stressors and their potential interaction. Furthermore we established criteria that an ideal assessment method for multiple stressors should fulfill in order to be effective and comprehensive.
Moving on from this baseline we looked at various proposed assessment methods and case studies of marine health to get an overview of available assessment methods, including univariate, as well as multivariate methods. By this literature review, we were able to detect and separate several individual assessment methods, some more commonly used and recognized than other, more novel concepts. These methods included Modelling, Cumulative Impact Mapping, Impact Ratind and Indexes. Based on the earlier established criteria, we evaluated these methods while taking into consideration the demands, availability of tools and background information that we acquired in the theory section in order to detect the strength, weaknesses and possible pitfalls of each method. Hence we came to the conclusion that a single method will not cover all the established methods sufficiently and consequently, a combination of methods is required to establish a holistic assessment method for multiple stressors. This conjunction of single methods, termed meta-methods, have already been taken into consideration in several reviews, which recommend similar tiered approaches. Analyzing and comparing the different steps of proposed meta-methods, we searched for similarities and generally consistent steps, which can be found in all meta-method approaches of multiple stressors assessments. As a result we created a merged meta-method including our own considerations and improvements. This meta-method, including nine different steps, is the attempt to find a holistic and extensive assessment methods for multiple stressors in the Anthropocene.
The recommended tiered methodology starts with the first two steps which define and determine the background, baseline and underlying problem of the assessment method, to ensure a targeted evaluation. The next step is to create a conceptual model of the ecosystem to get an substantial view by structuring the properties and indicators which define ecosystem health. Moving on from that present drivers can be indetified and stressors that influence the ecosystem can be ranked by their individual effect. By Cumulative Impact Mapping, the cumulative effects and potential interactions of the stressors can be detected. The following step is to outline the gained infromation in an a concise coceptual framework to have hollistic view of stressor interactions, ecosystem dynamics and the effects of potential interactions between these. The last step describes the challenges to quantify the gained knowledge in a way that displays vulnerability, trends and the most destructive stressor dynamics to give a concise review for further ecosystem management. For this quantfication we recommend modelling as a reliable method but also give the option of the adverse outcome pathway method.