CBMA - Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal.
CIBIO/InBIO - Research Center in Biodiversity and Genetic Resources, University of Porto, Campus Agrário de Vairão, Vairão, Portugal; CIIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208 Matosinhos, Portugal.
Sci Total Environ. 2019 Feb 1;649:938-948. doi: 10.1016/j.scitotenv.2018.08.341. Epub 2018 Aug 27.
Freshwater bivalves have suffered major global declines, being the introduction of invasive alien species (IAS) an important, but not well studied, mechanism of threat. This study assessed the predator-prey relationship between two non-native crayfish species (Procambarus clarkii and Pacifastacus leniusculus) and three native (Anodonta anatina, Potomida littoralis and Unio delphinus) and one non-native (Corbicula fluminea) freshwater bivalve species through experiments in laboratory and validation under natural conditions (Sabor River basin, Portugal). All native bivalve species were preyed both in laboratory and in the field; however, both crayfish species were unable to prey C. fluminea. Predation was dependent on crayfish and bivalve species but was not affected neither by crayfish nor bivalve sizes. In the laboratory, the most preyed species by both crayfishes was A. anatina. On average, this species was preyed at least 12% more than other species, when crayfishes had a choice. Similar results were found in the field. We also found signs of competition between both crayfishes, being P. clarkii more dominant and aggressive as this species, on average, manipulated the bivalves 63.6% more times and 24:33 min longer than P. leniusculus, and initiated 55.8% more agnostic bouts. Our results support the idea that P. clarkii and P. leniusculus can affect native freshwater bivalves, but clear interspecific differences were detected. Both crayfishes may have direct and indirect impacts on bivalve populations by increasing mortality or by reducing their fitness. In addition, since both crayfishes do not prey C. fluminea, they offer this IAS another advantage over native bivalves. Given the widespread distribution of both P. clarkii and P. leniusculus and the threatened status of many freshwater bivalves, the dynamics and impacts of this relationship should be taken in account in the implementation of management measures devoted to the conservation of native freshwater bivalves.
淡水双壳贝类在全球范围内大量减少，而引入入侵的外来物种（IAS）是一种重要但研究不足的威胁机制。本研究通过实验室实验和自然条件下的验证（葡萄牙 Sabor 河流域），评估了两种非本地螯虾物种（Procambarus clarkii 和 Pacifastacus leniusculus）与三种本地（Anodonta anatina、Potomida littoralis 和 Unio delphinus）和一种非本地（Corbicula fluminea）淡水双壳贝类物种之间的捕食者-猎物关系。所有本地双壳贝类物种在实验室和野外都受到捕食；然而，两种螯虾物种都无法捕食 C. fluminea。捕食行为取决于螯虾和双壳贝类物种，但不受螯虾和双壳贝类大小的影响。在实验室中，两种螯虾最常捕食的物种是 A. anatina。平均而言，当螯虾有选择时，这种物种被捕食的比例至少比其他物种高 12%。在野外也得到了类似的结果。我们还发现了两种螯虾之间存在竞争的迹象，P. clarkii 更为占优势和具有攻击性，因为这种物种平均比 P. leniusculus多操纵双壳贝类 63.6%的时间，长 24:33 分钟，并且发起 55.8%更多的无差别攻击。我们的研究结果支持了 P. clarkii 和 P. leniusculus 可以影响本地淡水双壳贝类的观点，但也发现了明显的种间差异。两种螯虾都可能通过增加死亡率或降低其适应性来直接或间接影响双壳贝类种群。此外，由于两种螯虾都不捕食 C. fluminea，因此它们为这种 IAS 提供了相对于本地双壳贝类的另一个优势。鉴于 P. clarkii 和 P. leniusculus 的广泛分布以及许多淡水双壳贝类的濒危状态，在实施旨在保护本地淡水双壳贝类的管理措施时，应考虑这种关系的动态和影响。
