Table_2_Feeding on the smallest cells: an in situ study of picoplankton capture by bivalve molluscs from oligotrophic waters.xlsx

IntroductionBivalve molluscs are among the most prominent coastal benthic-suspension-feeders and their farming is the largest and fastest-growing sector of aquaculture. More than a century of intensive laboratory studies (but surprisingly few in-situ studies) has yielded the consensus view that bivalves mainly capture particles >4µm. Nonetheless, bivalves thrive throughout the world’s oceans that are mostly oligotrophic, characterized by low food concentration and dominated by minute autotrophic picoplankton (<2 µm).
MethodWe measured, in situ, the capture efficiency of naturally occurring planktonic cells by five suspension-feeding bivalve species from four families and three orders, residing in two oligotrophic basins: the Red Sea and the East Mediterranean Sea.
ResultsThree species captured micron and submicron autotrophic cells with high efficiency (60-90%), suggesting a wider trophic niche than hitherto believed. In contrast, two sympatric species captured mainly particles >10 µm.
DiscussionThese results suggest that the same basic anatomical tool kit, variably modulated according to taxa, habitat, or life history traits, enables the remarkable evolutionary and ecological success of bivalves in trophically-diverse habitats.

引言
双壳类软体动物（Bivalve molluscs）是最具代表性的沿海底栖滤食生物类群之一，其养殖是水产养殖（aquaculture）领域规模最大、增长最快的分支。尽管已有一个多世纪的深入实验室研究（但原位研究（in-situ）却相对稀缺），学界已达成共识：双壳类主要捕获粒径大于4μm的颗粒物。然而，双壳类广泛分布于全球绝大多数贫营养海域——这类海域食物浓度极低，且以粒径小于2μm的自养超微型浮游植物为优势类群。

方法
本研究于原位条件下，测定了栖息于红海与东地中海这两个贫营养海域的、隶属于4个科、3个目的5种滤食性双壳类物种对天然浮游细胞的捕获效率。

结果
其中3个物种对微米级与亚微米级自养细胞具备较高捕获效率（60%~90%），表明其营养生态位宽度远超此前学界认知；与之形成鲜明对比的是，2种同域分布的物种仅主要捕获粒径大于10μm的颗粒物。

讨论
上述结果表明，同一套基础解剖学功能组件可根据类群、栖息环境或生活史特征进行差异化调控，这正是双壳类在营养结构多样的生境中取得显著进化与生态成功的关键所在。