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We assess the application of the second-generation Environmental Sample Processor (ESP) for the detection of harmful algal bloom (HAB) species in field and laboratory settings using two molecular probe techniques: a sandwich hybridization assay (SHA) and fluorescent in situ hybridization (FISH). During spring 2006, the first time this new instrument was deployed, the ESP successfully automated application of DNA probe arrays for various HAB species and other planktonic taxa, but non-specific background binding on the SHA probe array support made results interpretation problematic. Following 2006, the DNA array support membrane that we were using was replaced with a different membrane, and the SHA chemistry was adjusted. The sensitivity and dynamic range of these modifications were assessed using 96-well plate and ESP array SHA formats for several HAB species found commonly in Monterey Bay over a range of concentrations; responses were significantly correlated (p < 0.01). Modified arrays were deployed in 2007. Compared to 2006, probe arrays showed improved signal:noise, and remote detection of various HAB species was demonstrated. We confirmed that the ESP and affiliated assays can detect HAB populations at levels below those posing human health concerns, and results can be related to prevailing environmental conditions in near real-time.

In this contribution, we assess the application of methodology used in a novel in situ remote sampling platform, the environmental sample processor (ESP), for the identification and enumeration of a harmful algal species, the domoic acid-producing diatom Pseudo-nitzschia australis, using 2 molecular assays: a sandwich hybridization assay (SHA) and fluorescent in situ hybridization (FISH). Both the SHA and FISH assays were initially designed as laboratory-based methods that are now emulated in the ESP. Response of the SHA to a range of concentrations of P. australis using the laboratory (96-well plate) and ESP (DNA probe array) formats showed that the two were highly correlated. Enumeration of cells filtered and archived for FISH using a manifold designed for laboratory applications agreed well with counts of cells filtered and archived in the ESP at ≥2.5 × 104 cells L−1. At lower concentrations, it becomes statistically unlikely to derive a reliable abundance estimate, suggesting that FISH is better suited for qualitative analyses unless the target organism is very abundant. We also assessed the suitability of an oligonucleotide as synthetic target sequence to act as a SHA reagent quality control and internal standard for the plate assay. This was successful, but the probe and/or associated reagents were stable for only ~60 days. Our results show that the ESP is capable of detecting P. australis in near real-time and also supports whole-cell archival samples, making it a potentially useful tool for future research and monitoring initiatives.