Wagner et al. Simultaneously decontaminating angling gear for New Zealand Mudsnails (<i>Potamopyrgus antipodarum</i>) and Didymo (<i>Didymosphenia geminata</i>): a comparison of two chemical approaches. Data and R code

<b><i>Objective: </i></b>Successful invasion of AIS hinges on effective dispersal which is often greatly facilitated by human activities. A common dispersal mechanism is “hitchhiking’” on aquatic recreational gear and equipment including fishing boats and waders. Two recent co-occurring AIS in the rivers within the Laurentian Great Lakes region are New Zealand mudsnails (NZMS; <i>Potamopyrgus antipodarum</i>) and the algae Didymo (<i>Didymosphenia geminata</i>). Here, we developed and assessed an angling gear chemical decontamination method for NZMS and Didymo.<b><i>Methods:</i></b> Using a fully crossed experimental design, we tested the effectiveness of two household cleaning products (Dawn® dish detergent and the cleaning product Formula 409®) as a decontamination method against NZMS and Didymo. Briefly, we compared the survival and photosynthetic rates of NZMS and Didymo, respectively, when exposed to dish detergent, Formula 409, and a deionized water control to<i> </i>two application techniques (soaking and spraying), and application duration (10- and 20-minutes). NZMS survivorship was assessed over 96 h. Periphyton dominated by Didymo was removed from rocks and oxygen concentrations monitored following a closed chamber photosynthetic assay. Both NZMS survivorship and Didymo photosynthetic rates were assessed with a three-way analysis of variance.<b><i>Result</i></b>: Mean survivorship for NZMS was the greatest for NZMS receiving control water and dish detergent, then Formula 409. Regardless of duration (10- or 20-minute) survivorship of 0% was observed after soaking with Formula 409, while spraying resulted in a survivorship was more variable. Photosynthetic rates of Didymo-dominated periphyton depended on the chemical treatment and application. Significantly lower photosynthetic rates were observed in Didymo that was exposed to dish detergent (5.66 x 10^-5 mg/L/h/mg) and Formula 409 (-0.0003 mg/L/h/mg) compared to the water control (0.003 mg/L/h/mg).<b><i>Conclusion:</i></b> Dish detergent, while effective as a decontaminant for Didymo, is not effective for NZMS. Soaking angling gear in Formula 409 is an effective decontaminant for Didymo and NZMS; however, soaking wading gear is unlikely to be consistently used by wading anglers. Therefore, thorough spraying with Formula 409 is likely to be the more implemented and practical method for minimizing spread of these two invasive species.<b><i>研究目标：</i></b> 外来水生入侵物种（Aquatic Invasive Species，简称AIS）的成功定殖依赖于高效扩散，而人类活动往往极大地促进了这一过程。其中一种常见的扩散机制是通过水生休闲渔具及装备“搭便车”传播，包括渔船及涉水装备。近期在圣劳伦斯五大湖区域河流中同时出现的两种AIS分别为新西兰泥螺（New Zealand mudsnails, NZMS; <i>Potamopyrgus antipodarum</i>）与双眉藻（Didymosphenia geminata, Didymo）。本研究旨在开发并评估一种针对新西兰泥螺与双眉藻的渔具化学消毒方法。<b><i>研究方法：</i></b> 本研究采用全交叉实验设计，测试了两款家用清洁产品——Dawn®餐具洗洁精与Formula 409®清洁剂——作为新西兰泥螺与双眉藻消毒手段的有效性。简言之，我们分别将新西兰泥螺与双眉藻暴露于洗洁精、Formula 409®清洁剂及去离子水对照组中，同时设置两种施药方式（浸泡与喷雾）以及两种作用时长（10分钟与20分钟），并比较二者的存活率与光合速率。新西兰泥螺的存活率通过96小时的持续观测进行评估。我们从岩石表面刮取以双眉藻为优势类群的周丛藻类，并通过密闭室光合测定法监测溶氧浓度变化。本研究采用三因素方差分析对新西兰泥螺存活率与双眉藻光合速率两组数据进行统计检验。<b><i>研究结果：</i></b> 新西兰泥螺的平均存活率以去离子水对照组与洗洁精处理组最高，其次为Formula 409®处理组。无论作用时长为10分钟还是20分钟，经Formula 409®浸泡处理的新西兰泥螺存活率均为0%；而喷雾处理后的存活率则波动更大。以双眉藻为优势类群的周丛藻类光合速率取决于化学处理方式与施药手段。与去离子水对照组（0.003 mg/L/h/mg）相比，经洗洁精（5.66 × 10^-5 mg/L/h/mg）与Formula 409®（-0.0003 mg/L/h/mg）处理的双眉藻光合速率均显著降低。<b><i>研究结论：</i></b> 尽管洗洁精对双眉藻具有良好的消毒效果，但对新西兰泥螺无效。将渔具浸泡于Formula 409®清洁剂中可有效杀灭新西兰泥螺与双眉藻，但涉水垂钓者通常难以坚持采用浸泡方式清洁涉水装备。因此，使用Formula 409®对渔具进行全面喷雾处理，是目前两种入侵物种防控推广中更具实用性的方法，可有效降低二者的扩散风险。