啃食性端足类强壮藻钩虾对筼筜湖三种大型海藻的摄食选择性

为了评估啃食性端足类强壮藻钩虾Ampithoe valida对筼筜湖大型海藻群落的影响,作者在实验室内开展了强壮藻钩虾对筼筜湖三种大型海藻(绿藻石莼Ulva lactuca和根枝藻Rhizoclonium sp.、红藻细基江蓠繁枝变种Gracilaria tenuistipitata var. liui)的摄食实验,并分析了大型海藻的营养价值是否对强壮藻钩虾的摄食选择产生影响。结果显示,在无选择性摄食实验中,强壮藻钩虾的摄食率与海藻的干湿比和鲜藻总有机碳含量有着明显的负相关关系,这表明强壮藻钩虾有明显的补偿摄食行为,能通过增加低营养价值藻类的摄食量来满足自身代谢的需求。强壮藻钩虾对绿藻石莼和根枝藻有明显的摄食偏好,对它们的摄食率分别占总摄食率的40.6%和57.1%,而红藻细基江蓠繁枝变种则属于偶然性摄食的种类,海藻的营养价值并没有对强壮藻钩虾的摄食选择产生影响。不过,强壮藻钩虾对绿藻的摄食偏好并没有在筼筜湖形成一个以红藻占主导的大型海藻群落,这可能是由于筼筜湖超富营养化的水体使得来自强壮藻钩虾的下行控制已经无法抑制来自超富营养化的水体通过上行控制对绿藻生长的促进作用。

The feeding selectivity of an herbivorous amphipod Ampithoe valida on three dominant macroalgal species of Yundang Lagoon

we conducted no-choice and multiple-choice feeding assays for A. valida on three dominant macroalgal species of Yundang Lagoon (i.e. Ulva lactuca, Gracilaria tenuistipitata var. liui and Rhizoclonium sp.) and analyzed the relations between algal nutritional value (i.e. dry mass/wet mass: DM/FM, TOC, TN, protein contents) and feeding preference of A. valida. The results showed that there is a significant negative relationship of feeding rates against DM/FM and TOC of fresh algae in no-choice feeding assays, indicating that A. valida can use quantity to compensate quality when nutritional value of macroalgae was low. In multiple-choice feeding assays, A. valida preferably consumed U. lactuca and Rhizoclonium sp. when multiple macroalgal species were simultaneously offered. Its feeding rates inversely corresponded with TOC and protein contents of algae, but no related with TN, suggesting low effects of nutritional traits of macroalgae on the feeding selectivity of the amphipod.