Department of Biology, University of Louisiana at Lafayette, Box 43602, Lafayette, LA, 70504, USA.
Department of Chemistry, University of Louisiana at Lafayette, Box 43700, Lafayette, LA, 70504, USA.
Arch Environ Contam Toxicol. 2018 Aug;75(2):306-315. doi: 10.1007/s00244-018-0515-0. Epub 2018 Feb 22.
The relationship between organisms and contaminants may be a two-way interaction: contaminants affecting the biota and the biota affecting the environmental fate and distribution of the contaminants. This may be especially so for sediment-dwelling organisms, because their burrowing and feeding can drastically influence sediment characteristics. The present study looked at the influence of the suspension-feeding stout razor clam Tagelus plebeius on the distribution of crude oil and pyrene in greenhouse mesocosm experiments. Water column turbidity and sediment redox also were monitored during the 15- to 30-day exposures to provide information on the influence of hydrocarbons and the razor clams on environmental conditions. For the experiment with crude oil, sediment was taken from the mesocosms at the end of the experiment, and the hydrocarbon-degradation potential was assessed in incubations with C-naphthalene. The experiments used four treatments: hydrocarbons present/absent and razor clams present/absent. Hydrocarbon dosing levels were relatively low (1 mL of oil or 30 mg of pyrene per mesocosm with 22 L of natural sediment and 11 L of seawater). The presence of the razor clams resulted in hydrocarbon concentrations at the sediment surface being 25% lower than in mesocosms without clams. No consistent effects were noted for polycyclic aromatic hydrocarbon (PAH) concentrations in the water column or in subsurface sediment. The naphthalene-degradation potential was elevated for sediment from mesocosms dosed with oil, but the presence of the clams did not affect this potential. The presence of the razor clams resulted in a lowering of water column turbidity, but no effect on sediment redox. The hydrocarbon addition had no effect on turbidity, but sediment redox was lowered. While results show that the presence of the razor clams resulted in a loss of hydrocarbons from the surface sediment, the other results do not provide a clear picture of the underlying mechanisms and the fate of the PAHs lost from the sediment surface. We hypothesize that the loss of surface sediment PAHs was due to burial of surface sediment and possibly bioaccumulation by the clams. While additional research is needed for further insights into underlying mechanisms, the present work demonstrates that the presence of sediment-burrowing suspension feeders decreases hydrocarbon levels in surface sediment. This means that assessments of the impact of an oil spill should pay attention to effects on these organisms and to their influence on the fate and distribution of the spilled oil.
污染物会影响生物群，而生物群也会影响污染物在环境中的归宿和分布。对于底栖生物来说尤其如此，因为它们的挖掘和进食行为会极大地影响沉积物的特性。本研究通过温室中观实验，观察了滤食性厚壳贻贝 Tagelus plebeius 对原油和芘在沉积物中分布的影响。在 15 至 30 天的暴露过程中，还监测了水柱浊度和沉积物氧化还原状况，以提供有关烃类和贻贝对环境条件影响的信息。在原油实验中，在实验结束时从中观实验中取出沉积物，并在含有萘的培养物中评估烃降解潜力。实验使用了四种处理方法：有/无烃类和有/无贻贝。烃类的投加水平相对较低（每个中观实验中加入 1 毫升油或 30 毫克芘，每个中观实验中使用 22 升天然沉积物和 11 升海水）。贻贝的存在使沉积物表面的烃浓度比没有贻贝的中观实验低 25%。在水柱或亚表层沉积物中，多环芳烃（PAH）的浓度没有一致的影响。添加油后，沉积物的萘降解潜力升高，但贻贝的存在并没有影响这种潜力。贻贝的存在降低了水柱浊度，但对沉积物氧化还原没有影响。烃类的添加对浊度没有影响，但降低了沉积物氧化还原。虽然结果表明贻贝的存在导致表层沉积物中烃类的损失，但其他结果并没有清楚地说明从沉积物表面损失的 PAHs 的潜在机制和归宿。我们假设，表层沉积物中 PAHs 的损失是由于表层沉积物的埋藏和可能被贻贝生物积累。虽然需要进一步的研究来深入了解潜在机制，但目前的工作表明，挖掘沉积物的底栖滤食性动物的存在会降低表层沉积物中的烃类水平。这意味着评估溢油事故的影响时，应注意这些生物的影响及其对溢油的归宿和分布的影响。
