Cross-scale implications of marine ecosystem indicator selection and interpretation

• Ecosystem indicators are employed at many spatial as well as jurisdictional scales. • By comparing indicators across nested scales, we considered selection and trends. • With different scales come different levels of indicator specificity and complexity. • 47 indicators were shared by two or more case studies. • Only 1 indicator was used in each, and the mean number of indicators shared was 11.8. Ecosystems processes, functions and dynamics vary across spatio-temporal scales, resulting in important implications for how ecosystem indicators are both interpreted and applied across spatial scales. In this study, we investigate selected, applied indicator suites at various spatial and jurisdictional scales in the USA to examine how scale affects indicator selection, analyses, and representation of ecosystem processes in the context of ecosystem assessments. To investigate how the spatial scale of indicators makes a difference in how they are selected and interpreted, we compared all selected indicator suites to identify common, focal indicators. We then accessed each common indicator’s original, selected data source and compared larger trends within each common indicator across scales within each region. We compared these indicators to determine how trends and analyses vary across different spatial scales. By comparing common, shared indicator data between projects, we saw more sensitivity, specificity and variability at smaller scales, but also noted shared patterns in different scales of inquiry in the same geographic coastal region. For example, it was shown that while the analysis of common indicators use different data and data frequency for different case studies, the often selected indicator of marine heat/SST gave a complementary, consistent perspective when investigated at the same frequency and in the same region across spatial scales. As more effort towards ecosystem based management is made, it becomes increasingly important to consider indicators both specific to a project scale as well as indicators that function at scales that encompass various project levels and jurisdictions.