Abstract
The complexity and natural variability of ecosystems present a challenge for reliable detection of change due to anthropogenic influences. This issue is exacerbated by necessary trade-offs that reduce the quality and resolution of survey data for assessments at large scales. The Peace-Athabasca Delta (PAD) is a large inland wetland complex in northern Alberta, Canada. Despite its geographic isolation, the PAD is threatened by encroachment of oil sands mining in the Athabasca watershed and hydroelectric dams in the Peace watershed. Methods capable of reliably detecting changes in ecosystem health are needed to evaluate and manage risks. Between 2011 and 2016, aquatic macroinvertebrates were sampled across a gradient of wetland flood frequency, applying both microscope-based morphological identification and DNA metabarcoding. By using multispecies occupancy models, we demonstrate that DNA metabarcoding detected a much broader range of taxa and more taxa per sample compared to traditional morphological identification and was essential to identifying significant responses to flood and thermal regimes. We show that family-level occupancy masks high variation among genera and quantify the bias of barcoding primers on the probability of detection in a natural community. Interestingly, patterns of community assembly were nearly random, suggesting a strong role of stochasticity in the dynamics of the metacommunity. This variability seriously compromises effective monitoring at local scales but also reflects resilience to hydrological and thermal variability. Nevertheless, simulations showed the greater efficiency of metabarcoding, particularly at a finer taxonomic resolution, provided the statistical power needed to detect change at the landscape scale.
Highlights
Tackling the global loss of biodiversity [1] is hindered by a lack of basic biological information needed to guide sustainable management strategies [2]
The Peace–Athabasca Delta (PAD) in northern Alberta, Canada (Fig. 1 and ref. 14) is North America’s largest inland delta (∼6,000 km2) and is located at the confluence of the Peace and Athabasca Rivers, consisting of hundreds of lakes and wetlands that become connected during flood events, when spring snowmelt leads to ice jams [15, 16]
The CABIN Fcount model predicted total abundance was dominated by four taxa and suggested that almost all taxa were present everywhere within the PAD, with no environmental covariates retained in the final model
Summary
Tackling the global loss of biodiversity [1] is hindered by a lack of basic biological information needed to guide sustainable management strategies [2]. The accuracy, consistency, and resolution of taxonomic identification remains a constraint for many biomonitoring programs that must trade off data quality to make assessment protocols rapid and cost-effective [10] Aquatic macroinvertebrates exemplify this challenge, as their diversity of forms and functions are sensitive to multiple drivers of ecosystem condition. There have been concerns that the PAD could be affected by upstream developments, including current and proposed hydroelectric dams on the Peace River, continued expansion of oil sands mining on the Athabasca River to within 30 km of the park boundary, and climate change [17] Assessing how such factors influence the integrity of a natural wilderness is made more challenging by the paucity of biological surveys that have been conducted and the logistics of working in such a remote region. While surveys have followed established protocols from the Canadian Aquatic Biomonitoring Network (hereafter CABIN) [19], samples were processed using both traditional and DNA metabarcoding approaches, allowing us to test the power of each approach to support environmental management of the delta
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