Recent research into the spatiotemporal dynamics of eDNA in marine environments indicates that eDNA signals are highly localized and may dissipate beyond detection levels within a few hours of production. This affects whether single-timepoint eDNA sampling, which generally occurs during daylight hours, or cyclic (day/night) interval eDNA sampling is necessary to detect both diurnal and nocturnal marine species. Our study investigated short-term variability in eDNA derived from fishes and macroinvertebrates across three temperate reef sites in eastern Tasmania, Australia. Simultaneous eDNA and underwater visual census (UVC) diver transect surveys were conducted every 6 h over a 24-h period to investigate whether eDNA was able to detect marine species outside of their UVC-observed diel activity. We report that single-timepoint eDNA sampling can detect both diurnal and nocturnal species on temperate reefscapes. A lack of eDNA compositional turnover between day and night suggests that eDNA persists beyond 12 h and/or is continuously produced by both diurnal and nocturnal reef taxa, irrespective of diel behavioral changes observed by UVC. Given high eDNA sample variability, however, we recommend a high replication level (> 10 x 1 L samples) to produce robust site community composition profiles. This study builds on emerging literature on short-term variability in eDNA, assisting in the design of future eDNA studies at sites with pronounced variation in faunal activity between day and night.

Diel partitioning of animals within ecological communities is widely acknowledged, yet rarely quantified. Investigation of most ecological patterns and processes involves convenient daylight sampling, with little consideration of the contributions of nocturnal taxa, particularly in marine environments. Here we assess diel partitioning of reef faunal assemblages at a continental scale utilizing paired day and night visual census across 54 shallow tropical and temperate reefs around Australia. Day-night differences were most pronounced in the tropics, with fishes and invertebrates displaying distinct and opposing diel occupancy on coral reefs. Tropical reefs in daytime were occupied primarily by fishes not observed at night (64% of all species sighted across day and night, and 71% of all individuals). By night, substantial emergence of invertebrates not otherwise detected during sunlit hours occurred (56% of all species, and 45% of individuals). Nocturnal emergence of tropical invertebrates corresponded with significant declines in the richness and biomass of predatory and herbivorous diurnal fishes. In contrast, relatively small diel changes in fishes active on temperate reefs corresponded to limited nocturnal emergence of temperate invertebrates. This reduced partitioning may, at least in part, be a result of strong top-down pressures from fishes on invertebrate communities, either by predation or competitive interference. For shallow reefs, the diel cycle triggers distinct emergence and retreat of faunal assemblages and associated trophic patterns and processes, which otherwise go unnoticed during hours of regular scientific monitoring. Improved understanding of reef ecology, and management of reef ecosystems, requires greater consideration of nocturnal interactions. Without explicit sampling of nocturnal patterns and processes, we may be missing up to half of the story when assessing ecological interactions.

Scientific working groups bring together experts from different disciplines and perspectives to tackle the "wicked problems" facing natural systems and society. Yet participants can feel overwhelmed or inadequate in groups within academic environments, which tends to be most acute at early career stages and in people from systematically marginalized backgrounds. Such feelings can block innovation that would otherwise arise from gaining the full spectrum of unique perspectives, knowledge and skills from a group. Drawing on personal experiences and relevant literature, we identify ten contribution strategies, ranging from generating ideas, analyzing data, and producing visuals to supporting facilitation. Next, we share approaches for an inclusive and supportive process, considering the roles of both participants and leads. Generating the most productive and relevant outcomes from working groups requires engaging the full team in a constructive and supportive environment. We advocate that adopting inclusive approaches that respect the diversity of personality types and perspectives will lead to more innovative solutions to achieve conservation and sustainability goals.

Human society is dependent on nature 1 , 2 , but whether our ecological foundations are at risk remains unknown in the absence of systematic monitoring of species’ populations 3 . Knowledge of species fluctuations is particularly inadequate in the marine realm 4 . Here we assess the population trends of 1,057 common shallow reef species from multiple phyla at 1,636 sites around Australia over the past decade. Most populations decreased over this period, including many tropical fishes, temperate invertebrates (particularly echinoderms) and southwestern Australian macroalgae, whereas coral populations remained relatively stable. Population declines typically followed heatwave years, when local water temperatures were more than 0.5 °C above temperatures in 2008. Following heatwaves 5 , 6 , species abundances generally tended to decline near warm range edges, and increase near cool range edges. More than 30% of shallow invertebrate species in cool latitudes exhibited high extinction risk, with rapidly declining populations trapped by deep ocean barriers, preventing poleward retreat as temperatures rise. Greater conservation effort is needed to safeguard temperate marine ecosystems, which are disproportionately threatened and include species with deep evolutionary roots. Fundamental among such efforts, and broader societal needs to efficiently adapt to interacting anthropogenic and natural pressures, is greatly expanded monitoring of species’ population trends 7 , 8 .

Marine ecosystems are structured by an array of natural and anthropogenic drivers, their diverse influences varying between different community types and across space. We assessed consistency in variation in composition and richness for three communities (macro- and meio-faunal communities associated with macroalgae, and soft-sediment infaunal communities) across natural and pollution gradients at the subcontinental scale of southeastern Australia. Community structure varied with natural environmental factors (temperature, wave exposure) and, to a lesser extent, pollutant loads (catchment effects, heavy metals, hydrocarbons and nutrients) across 43 sites spanning 2700 km. The community types showed differing sensitivities to pollutants: algal macrofauna was most strongly associated with hydrocarbon pollution and nutrient loading; algal meiofauna with heavy metals and nutrients; and infauna with catchment effects and nutrients. Different taxonomic resolutions were needed to detect significant pollution relationships for the three community types, indicating that monitoring programmes are most effective if pollutant- and fauna-specific.