Novel insights into marine fish biodiversity across a pronounced environmental gradient using replicated environmental DNA analyses

Safeguarding marine ecosystems is essential for maintaining ecosystem function and biodiversity, but effective monitoring of marine habitats can be logistically challenging, costly, and difficult to regularly implement. Environmental DNA-based biomonitoring is a rapidly growing tool that is non-destructive, cost-effective, and reliable. However, discrepancies in eDNA sampling protocols and methodology persist, which can greatly impact the interpretations of biomonitoring results, particularly across highly diverse ecosystems with historically elevated biodiversity. The South African coastal system is a unique and highly diverse ecoregion consisting of two ocean boundary currents creating one of the most diverse biological regions on the planet. Here, we present the first eDNA-based metabarcoding assessment of South African coastal fishes while also providing key management insights into study and sample design. We observed strong ecological associations with fish species richness across the extent of the South African coast, along with weaker associations with seasonality. We detected 466 operational taxonomic units across 112 of the 270 families described previously from the region, with greater species richness on the eastern subtropical coast compared to the western coast, which follows expected species richness patterns. Additionally, we provide evidence that biological replication is necessary to detect intra-site fish diversity and that three biological replicates are sufficient for capturing species diversity dynamics. Our work highlights the value of eDNA biomonitoring across space and time enabling biodiversity characterizations for the management of a gradient of coastal marine environments

Scale and scope matter when explaining varying patterns ofcommunity diversity in riverine metacommunities

Large-scale species and genetic metacommunity patterns are influenced by variation in environmental factors and distancebetween communities, according to previous studies. However, these studies often used different measures to assess patternsof metacommunity diversity, distances between communities and grain sizes at which environmental variables are measured.This hinders interpretations and generalizations of the underlying process that drive metacommunity diversity. We applied asynthetic and multi-analytical approach to identify general factors structuring the diversity of a large riverine metacommunity.Using complementing approaches we analyzed how distance, measured as Euclidean or topological distance, and environmentalfactors, assessed at different grain sizes, influenced different measures of metacommunity diversity (species richness, functionalrichness and phylogenetic diversity) of mayfly, stonefly and caddisfly species in a large river network (river Rhine, Switzerland).We found the amount of explained variation in species diversity was generally unaffected by grain size, but improved with the useof topological distance, compared to Euclidean distance. Variation in functional diversity was best explained by environmentalfactors at small grain sizes and topological distance. Variation in phylogenetic diversity was best explained when environmentalvariables were assessed at larger grain sizes and Euclidean distance was used. Overall, our results indicate that processesstructuring metacommunity diversity may differ at the species, functional or phylogenetic level of the community, as recentlypostulated in the metacommunity–phylogenetics approach. While such differences may hinder comparisons across studiesusing different methodologies, it offers opportunities to disentangle the structuring factors within metacommunities by applyingmultiple analytical approaches to the same dataset

Action Research in Social Entrepreneurship: A Framework for Involvement

"This paper presents a social entrepreneurship undertaking that has been both a motivation and exemplar to develop action research methods. The complexity of social entrepreneurship and action research processes are presented, highlighting the need for an organising framework that will both provide support and allow for flexibility. The Action Research Cycle, with five key episodes and an emphasis on the dynamics of ebb and flow, is proposed as a framework for understanding and managing social entrepreneurship projects. Drawing on the social entrepreneurship project Mushuk Muyu, examples highlight the application and use of the framework. The paper concludes with key insights, strengths and weaknesses, and the benefits of using the framework." (author's abstract

Executing multi-taxa eDNA ecological assessment via traditional metrics and interactive networks

Current approaches to ecological assessment are limited by the traditional morpho-taxonomic methods presently employed and the inability to meet increasing demands for rapid assessments. Advancements in high throughput sequencing now enable rapid high-resolution ecological assessment using environmental DNA (eDNA). Here we test the ability of using eDNA-based ecological assessment methods against traditional assessment of two key indicator groups (diatoms and macroinvertebrates) and show how eDNA across multiple gene regions (COI, rbcL, 12S and 18S) can be used to infer interactive networks that link to ecological assessment criteria. We compared results between taxonomic and eDNA based assessments and found significant positive associations between macroinvertebrate (p < 0.001 R2 = 0.645) and diatom (p = 0.015, R2 = 0.222) assessment metrics. We further assessed the ability of eDNA based assessment to identify environmentally sensitive genera and found an order of magnitude greater potential for 18S, versus COI or rbcL, to determine environmental filtering of ecologically assessed communities. Lastly, we compared the ability of traditional metrics against co-occurrence network properties of our combined 18S, COI and rbcL indicator genera to infer habitat quality measures currently used by managers. We found that transitivity (network connectivity), linkage density and cohesion were significantly associated with habitat modification scores (HMS), whereas network properties were inconsistent with linking to the habitat quality score (HQS) metric. The incorporation of multi-marker eDNA network assessment opens up a means for finer scale ecological assessment, currently limited using traditional methods. While utilization of eDNA-based assessment is recommended, direct comparisons with traditional approaches are difficult as the methods are intrinsically different and should be treated as such with regards to future research. Overall, our findings show that eDNA can be used for effective ecological assessment while offering a wider range of scope and application compared to traditional assessment methods

Annual time-series analysis of aqueous eDNA reveals ecologically relevant dynamics of lake ecosystem biodiversity

The use of environmental DNA (eDNA) in biodiversity assessments offers a step-change in sensitivity, throughput and simultaneous measures of ecosystem diversity and function. There remains, however, a need to examine eDNA persistence in the wild through simultaneous temporal measures of eDNA and biota. Here, we use metabarcoding of two markers of different lengths, derived from an annual time series of aqueous lake eDNA to examine temporal shifts in ecosystem biodiversity and in an ecologically important group of macroinvertebrates (Diptera: Chironomidae). The analyses allow different levels of detection and validation of taxon richness and community composition (β-diversity) through time, with shorter eDNA fragments dominating the eDNA community. Comparisons between eDNA, community DNA, taxonomy and UK species abundance data further show significant relationships between diversity estimates derived across the disparate methodologies. Our results reveal the temporal dynamics of eDNA and validate the utility of eDNA metabarcoding for tracking seasonal diversity at the ecosystem scale