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Discharge of treated sewage effluent to rivers can degrade aquatic ecosystem quality, interacting with multiple stressors in the wider catchment. In predominantly rural catchments, the river reach influence of point source effluents is unknown relative to complex background pressures. We examined water column, sediment and biofilm biogeochemical water quality parameters along river transects (200 m upstream to 1 km downstream) during summer at five wastewater treatment works (WWTW) in Scotland. Treated sewage effluent (subset, n = 3) pollutant concentrations varied between sites. Downstream concentration profiles of water and sediment biogeochemical parameters showed complex spatial changes. A hypothesised point source signature of elevated concentrations of pollution immediately downstream of WWTW then a decaying pollution 'plume' did not commonly occur. Instead, elevated soluble reactive phosphorus (SRP), ammonium and coliforms (maximum 0.23 mgP/l, 0.33 mgN/l and >2 × 10 6 MPN/100 ml) occurred immediately downstream of two WWTW, whereas some downstream pollutant concentrations decreased. Microbial substrate respiration responses only differed 1 km downstream. Significantly greater concentrations of sediment metal occurred >500 m downstream, likely due to the redeposition of historic contaminated sediments. Significantly lowered chlorophyll-a downstream of one WWTW coincided with elevated metals, despite water SRP and sediment P increases. Overall, stress caused to microbes and algae by effluent contaminants outweighed the subsidy effect of WWTW nutrients. We observed variable effluent flows to the rivers limited localised pollution downstream of WWTW and overall influence of arable land cover on river water quality. Together, this challenges views of consistently discharging point sources impacting low dilution sensitive rivers in summer contrasting with 'diffuse' sources. Thus, river water column and benthic compartments are altered at varying scales by point sou

Background: The Lower Kinabatangan Floodplain in Sabah, Malaysian Borneo, contains a partially fragmented rainforest corridor, varying in width on either side of the Kinabatangan River. It contains a range of secondary forest habitats and supports an extremely high level of biodiversity. Extensive oil palm plantations surround the forest, and in some areas native trees have been replanted in order to create a continuous rainforest canopy. We are interested in the resilience of the forest to reductions in size, increased fragmentation, and changes in the composition of animals involved in pollination and dispersal. A DNA barcode library of adult trees is being created and used to identify saplings in order to investigate forest regeneration. We are also assessing the feasibility of using DNA metabarcoding to conduct rapid biodiversity assessments of the rainforest understory. Results: We have sampled 10 permanent plots (each 50 m2) within established forest and two plots within replanted regeneration sites. In total, 385 adult trees and 872 saplings have been DNA barcoded with rbcL, matK, trnL, and ITS2. A biodiversity sweep, consisting of collecting small leaf samples of every sapling for DNA metabarcoding has been conducted for eight plots. We will compare richness, diversity, and phylogenetic composition of adult and sapling communities within secondary forest habitats and the planted regeneration sites. Significance: Rainforest destruction continues to accelerate with significant losses of biodiversity and its associated ecosystem services. In Sabah, intact forest within protected areas covers only 8% of the land surface. As primary forest has been lost, secondary forests are now assuming greater importance for biodiversity. There is an urgent need for increased understanding of natural regeneration within these forests and robust protocols for replanting. DNA barcoding allows rapid identification for biodiversity assessment, monitoring, and conservat