Data for refining copper concentrations using the Biotic Ligand Model to maximize zebra mussel control while minimizing non-target effects

Copper in various forms can be toxic to aquatic organisms at high concentrations and has been used as a pesticide in lake management since the early 1900s. Managers have recently extended this use to control aquatic invasive species, including zebra mussels (Dreissena polymorpha). Because copper toxicity changes with changing concentrations of water chemistry parameters (e.g., pH, temperature, and other cations such as Ca2+ and Mg2+), using the same copper concentration to target the same species in two different waterbodies could have different outcomes. However, past zebra mussel control projects have selected copper concentrations irrespective of water chemistry differences. We demonstrate, in a two-part study, how measuring water chemistry parameters and using the Biotic Ligand Model (BLM) can help predict a site-specific copper concentration that will kill zebra mussels while minimizing effects on non-target species. We first tested the application of the BLM for predicting the effects of a copper concentration on non-target species. We found that Daphnia magna (daphnia) had a 50% chance of survival at 9.50 µg Cu/L (i.e., the 50% lethal concentration, LC50), within our BLM-predicted range of 3.38-16.95 µg Cu/L LC50 values. Given the accuracy of our prediction, in the future, managers could make similar predictions and tailor copper concentrations to their management goals. Secondly, we measured zebra mussel larvae (veliger) mortality at added copper concentrations ranging from 0-191 µg Cu/L and assessed exposure–response using a logistic regression model that also included water chemistry parameters. This model can be applied to future projects; using it, managers can predict the amount of copper in a particular waterbody that will kill a predetermined proportion of zebra mussels and simultaneously predict what non-target effects to monitor or expect.

不同形态的铜在高浓度下会对水生生物产生毒性，自20世纪初以来，铜便被用作湖泊管理中的杀虫剂。近年来，水体管理者将这一用途拓展至防控水生入侵物种，其中包括斑马贻贝（Dreissena polymorpha）。由于铜的毒性会随水体化学参数（如pH、温度，以及Ca²+、Mg²+等其他阳离子）的浓度变化而改变，因此在两个不同水体中使用相同铜浓度防控同一物种，可能会产生不同的防控效果。然而，过往的斑马贻贝防控项目在选定铜浓度时，并未考虑水体化学性质的差异。本研究分为两个部分，我们在此展示了：通过测定水体化学参数并应用生物配体模型（Biotic Ligand Model, BLM），如何预测适配特定水体的铜浓度——该浓度既可杀灭斑马贻贝，又能最大程度降低对非靶标物种的影响。首先，我们验证了生物配体模型在预测铜浓度对非靶标物种影响方面的应用效果。实验结果显示，大型溞（Daphnia magna）在铜浓度为9.50 μg Cu/L时的存活率为50%，即半数致死浓度（50% Lethal Concentration, LC50），该结果处于我们通过生物配体模型预测的3.38~16.95 μg Cu/L LC50区间内。鉴于本研究的预测精度，未来水体管理者可通过类似的预测方法，根据自身管理目标定制适配的铜浓度。其次，我们测定了在0~191 μg Cu/L的梯度添加铜浓度下，斑马贻贝面盘幼虫（veliger）的死亡率，并采用纳入了水体化学参数的逻辑回归模型评估其暴露-响应关系。该模型可应用于未来的防控项目：借助该模型，管理者可预测特定水体中杀灭预设比例斑马贻贝所需的铜用量，同时还能预判需要监测或关注的非靶标效应。