Environmental DNA (eDNA) analysis offers a time- and cost-efficient method to perform temporal and spatial observations of aquatic environments, providing a wealth of biodiversity data. Unfortunately, most protocols require manual collection of eDNA samples using highly skilled individuals to capture, filter and store the samples before they can be sent to a lab for analysis. Automated samplers exist to reduce this front-end collection burden, but they tend to be bulky and costly. Here we describe an eDNA sampler designed to be user-friendly and to automate the entire sample collection process. We describe and characterize our eDNA sampler, which offers multi-sample capture, preservation, and self cleaning to reduce cross contamination. DNA sequencing was performed on samples collected using the eDNA sampler as well as a traditional niskin bottle-based protocol at six stations in Bedford Basin, Nova Scotia, Canada. The two approaches showed similar algal and bacterial taxonomic compositions, demonstrating the ability of the eDNA sampler to generate results comparable to those obtained through gold-standard protocols.

In situ nutrient sensors are essential for furthering our understanding of phosphate flux dynamics in marine environments during short term events such as tidal cycles and algae blooms. Here, we present a fully automated in situ phosphate analyzer based on inlaid microfluidic absorbance cells with embedded beam-steering optics. The microfluidic component employs colorimetric absorbance spectrophotometry, using the phosphomolybdenum blue (PMB) assay modified by the addition of polyvinylpyrrolidone (PVP), to measure phosphate concentrations in seawater. Bench top calibrations and temperature sensitivity studies characterize the sensor’s performance in the laboratory. It achieves a practical limit of detection (LOD) of less than 100 nM and a high precision, with a relative standard deviation of less than 1.5% across five measurements. Two consecutive field deployments serve as validation tests for its intended in situ applications. The sensor is first deployed from a jetty at a depth of 6 m, with simultaneous bottle samples taken for confirmation. It is next deployed on the Stella Maris testbed, a multi-sensor seabed platform (MSSP), 100 m offshore and 9 m deep in the inlet to the Bedford Basin in Nova Scotia, Canada.