Developing benthic monitoring programmes to support precise and representative status assessments: a case study from the Baltic Sea

Abstract

Benthic habitats and communities are key components of the marine ecosystem. Securing their functioning is a central aim in marine environmental management, where monitoring data provide the base for assessing the state of marine ecosystems. In the Baltic Sea, a > 50-year-long tradition of zoobenthic monitoring exists. However, the monitoring programmes were designed prior to the current policies, primarily to detect long-term trends at basin-scale and are thus not optimal to fulfil recent requirements such as area-based periodic status assessments. Here, we review the current monitoring programmes and assess the precision and representativity of the monitoring data in status assessments to identify routes for improvement. At present, the monitoring is focused on soft-bottoms, not accounting for all habitat types occurring in the Baltic Sea. Evaluating the sources of variance in the assessment data revealed that the component accounting for variability among stations forms the largest proportion of the uncertainty. Furthermore, it is shown that the precision of the status estimates can be improved, with the current number of samples. Reducing sampling effort per station, but sampling more stations, is the best option to improve precision in status assessments. Furthermore, by allocating the sampling stations more evenly in the sub-basins, a better representativity of the area can be achieved. However, emphasis on securing the long-term data series is needed if changes to the monitoring programmes are planned.

Structural and functional effects of global invasion pressure on benthic marine communities—patterns, challenges and priorities

“…This is likely to be difficult because many historical datasets were natural history‐type inventories (focused on richness) that lacked measures of abundance, which is important for comparisons of structural composition. In parallel, there are emerging longer‐term repeated‐measures datasets of marine community dynamics that highlight the interacting roles of invasion and environmental perturbations in benthic systems (Chang et al., 2018; Nygård et al., 2020; Philippe et al., 2017). In NIS‐focused studies, native context is often lacking, resulting in disconnected records of native and non‐indigenous biodiversity for the same time and place.…”