Tracking fjord biodiversity through space and time: exploring methods to define reference conditions with benthic foraminifera

Abstract

This thesis aims to develop new methods to establish in situ reference conditions in nearshore marine environments, using morphospecies and sedimentary environmental DNA (eDNA and sedaDNA) metabarcoding analysis of the benthic foraminifera assemblages. The study focuses on well-studied fjord systems along the Skagerrak coast, to address “the estuarine quality paradox”, by delineating the anthropogenically produced environmental stress from that which is naturally a feature of transitional environments. Ecological Quality Status (EcoQs) assessment in environments that are most proximal to, and therefore disproportionally effected by, human activities is essential to preserve ecosystem services and mitigate further damage. Some key fundings of this thesis show that a) SedaDNA preservation is increased in low-oxygen environments that lack bioturbation, meaning this methodology could be particularly effective in areas effected by both natural and human enduced eutrophication B) Diversity indices calculated from morpho-taxonomic and genetic assemblages show coherent response to both contemporary and historical variation in environmental conditions C) SedaDNA analysis can help to resolve the ecological preferences of otherwise under studied taxonomic groups, such as monothalamids. Taxa consistently found to be associated with polluted, or stressed environmental conditions could represent novel indicator species for future biomonitoring studies. The ultimate goal of this thesis is to demonstrate that by integrating benthic foraminiferal morphospecies and genetic diversity, sensitivity and multimeric indices for use in biomonitoring; benthic foraminifera hold a high potential as a ‘biological quality element’ (BQE) in anoxic or polluted coastal environments, in which traditional monitoring strategies such as macrofaunal community analysis are not applicable.