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Summary Aqueous environmental DNA (eDNA) is an emerging efficient non‐invasive tool for species inventory studies. To maximize performance of downstream quantitative PCR (qPCR) and next‐generation sequencing (NGS) applications, quality and quantity of the starting material is crucial, calling for optimized capture, storage and extraction techniques of eDNA. Previous comparative studies for eDNA capture/storage have tested precipitation and ‘open’ filters. However, practical ‘enclosed’ filters which reduce unnecessary handling have not been included. Here, we fill this gap by comparing a filter capsule (Sterivex‐GP polyethersulfone, pore size 0·22 μm, hereafter called SX) with commonly used methods. Our experimental set‐up, covering altogether 41 treatments combining capture by precipitation or filtration with different preservation techniques and storage times, sampled one single lake (and a fish‐free control pond). We selected documented capture methods that have successfully targeted a wide range of fauna. The eDNA was extracted using an optimized protocol modified from the DNeasy® Blood & Tissue kit (Qiagen). We measured total eDNA concentrations and Cq‐values (cycles used for DNA quantification by qPCR) to target specific mtDNA cytochrome b (cyt b) sequences in two local keystone fish species. SX yielded higher amounts of total eDNA along with lower Cq‐values than polycarbonate track‐etched filters (PCTE), glass fibre filters (GF) or ethanol precipitation (EP). SX also generated lower Cq‐values than cellulose nitrate filters (CN) for one of the target species. DNA integrity of SX samples did not decrease significantly after 2 weeks of storage in contrast to GF and PCTE. Adding preservative before storage improved SX results. In conclusion, we recommend SX filters (originally designed for filtering micro‐organisms) as an efficient capture method for sampling macrobial eDNA. Ethanol or Longmire's buffer preservation of SX immediately after filtration is recommended. Preserved SX capsules may be stored at room temperature for at least 2 weeks without significant degradation. Reduced handling and less exposure to outside stress compared with other filters may contribute to better eDNA results. SX capsules are easily transported and enable eDNA sampling in remote and harsh field conditions as samples can be filtered/preserved on site.

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While environmental DNA (eDNA) is becoming increasingly established in biodiversity monitoring of freshwater ecosystems, the use of eDNA surveys in the marine environment is still in its infancy. Here, we use two approaches: targeted quantitative PCR (qPCR) and whole-genome enrichment capture followed by shotgun sequencing in an effort to amplify killer whale DNA from seawater samples. Samples were collected in close proximity to killer whales in inshore and offshore waters, in varying sea conditions and from the surface and subsurface but none returned strongly positive detections of killer whale eDNA. We validated our laboratory methodologies by successfully amplifying a dilution series of a positive control of killer whale DNA. Furthermore, DNA of Atlantic mackerel, which was present at all sites during sampling, was successfully amplified from the same seawater samples, with positive detections found in ten of the eighteen eDNA extracts. We discuss the various eDNA collection and amplification methodologies used and the abiotic and biotic factors that influence eDNA detection. We discuss possible explanations for the lack of positive killer whale detections, potential pitfalls, and the apparent limitations of eDNA for genetic research on cetaceans, particularly in offshore regions. K E Y W O R D S eDNA, environmental DNA, metagenomics, Orcinus orca, PCR, Scomber scombrus, wholegenome enrichment | 317 PINFIELD Et aL. S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section at the end of the article. How to cite this article: Pinfield R, Dillane E, Runge AKW, et al. False-negative detections from environmental DNA collected in the presence of large numbers of killer whales (Orcinus orca).

As an incidental finding in a general 'life-style' survey, amateur rugby footballers were found to drink prodigious (12-24 schooners per session) quantities of beer. Such drinking was regarded by the players as part of the traditions of mateship associated with the game. The need for intervention is discussed.

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In today's world of high operating costs and low oil prices new methods of construction are needed to ensure economic viability. One such way is to maximise the use of an existing infrastructure. Marathon utilized surplus power generated on Brae A and Brae B to supply the requirements of East Brae using transfer by 33kV sub-sea cable. First oil was produced in December 1993. This resulted in platform weight savings of ground 3000 tonnes, with cost savings in excess of £60 million. INTRODUCTION East Brae is the third of a three platform development located in the UK sector of the North Sea and operated by Marathon Oil UK on behalf of the Brue Group, see Fig, 1. First oil was produced from the East Brae reservoir, on schedule, during December 1993. In today 's world of high operating costs and low oil price, new methods of construction are required to ensure economic viability. One such way to reduce expenditure is to maximise the use of the existing infrastructure, thus reducing weight. capital expenditure and operating costs. Marathon utilised that existing surplus power generated on the Brae A and Brae B platforms to supply the power requirements of East Brae. This took the form of a "ring-main" between the three platforms. sec Fig. 2(Available in full paper). There are four dual fuelled turbine/generator units installed on Brae A, each rated at 20MW, giving a total capacity of SOMW, the load on this platform is now 33MW. On Brae B there are three dual fuelled turbine/generator units installed, each rated at 24MW, giving a total capacity of 72MW, the load on the platform is 27MW. This gives an installed field capacity of 152MW and a firm capacity of 128MW. (152 - 24), The final load on East Brae will eventually be in the order of 20MW. The total field power requirements will therefore be 33+27+20 = 80MW, which can be achieved by operating any five of the seven generators. This is sufficient for HT motor starting and also avoids the need to loud shed upon failure of a single generator. JUSTIFICATION Before a start could be made on the project it was necessary to confirm the feasibility of the proposed scheme and in order to arrive at that stage it was essential to make a number of assumptions. One of these was in respect of the platform loadings at the time when East Brae would come into production (late 1993). Other assumptions made, concerning the Electrical Engineering aspect, were that the existing switchgear was suitable to absorb the extra current loading and that the fault level ratings of the switchgear were capable of taking the added fault contribution when the three platforms were inter-connected. Load flow diagrams were produced showing the envisaged current flows when the platforms were interconnected. From these diagrams it was confirmed that the main bus-bar ratings were acceptable. The only modification required was that the "droppers" to the new circuit breakers for the sub-sea cable, from the main bus-bar, would have to be increased from 1600 amps to 2000 amps, the bus-bar rating.