Plankton community structure and carbon cycling in a coastal upwelling system. I: Bacteria, microprotozoans and phytoplankton in the diet of copepods and appendicularians
Plankton community structure and carbon cycling in a coastal upwelling system. I: Bacteria, microprotozoans and phytoplankton in the diet of copepods and appendicularians
复制标题
DOI：
10.3354/ame034151
复制
发表时间：
2004-02
影响因子：
1.4
通讯作者：
C. Vargas;H. González
中科院分区：
文献类型：
--
作者：
C. Vargas;H. González
2000年10月至2001年10月，利用沿海海湾(位于S 23度的智利北部梅吉隆斯湾上升流系统)中的自然板刺组合，进行了桡足类和附肢动物的放牧实验。基于大小分类的叶绿素数据的总碳摄取率表明，优势桡足类(Acartia tonsa、Centroages brchiatus、Oithona similis和Paracalanus paracalanus)的摄入量在2-8微克/分之间。-1d-1，而附尾虫(Oikopleura dioica和O.Longicauda)摄取~3~4微克Ind。-1d-1。即使当大多数尺足类以较大的细胞(23微米)高速觅食时，较小的桡足类也以类似的速度捕食纳米浮游生物(5至23微米)和微微浮游生物(5微米)。相比之下，形成链的硅藻被桡足类清除的速度非常低。细菌只能由附属者(~170到~400毫升)清除。-1d-1)，而异养原生动物在桡足类和附肢动物的食物中占相当大的比例(~10%-100%的体碳d-1)，特别是在南半球的春季。有时，异养生物对桡足类C的特异性摄食与自养细胞的摄食相似。大型纤毛虫和甲鞭毛虫被清除，但不被附着性-双管藻O.dioica摄取，这表明在它们的房子里捕获大细胞的机制，并意味着新鲜材料的快速出口。由于异养生物是这两类动物食物中的常见成分(桡足动物的杂食性和附肢动物的吞噬作用)，它们可能会影响这一上升流系统中的微生物食物网，从而影响碳输出。
Copepod and appendicularian grazing experiments using naturally occurring plank- tonic assemblages from a coastal embayment (Mejillones Bay, northern Chile upwelling system at 23o S) were conducted between October 2000 and October 2001. Total carbon ingestion rates based on size- fractioned chlorophyll data showed that dominant copepods (Acartia tonsa, Centropages brachiatus, Oithona similis and Paracalanus parvus) ingested between 2 and 8 µgC ind. -1 d -1 , while appendicu- larians (Oikopleura dioica and O. longicauda) ingested ~3 to 4 µgC ind. -1 d -1 . Even when most cope- pods were feeding on larger cells (> 23 µm) at high rates, the smaller copepods also grazed at similar rates on nanoplankton (5 to 23 µm) and picoplankton (<5 µm). In contrast, chain-forming diatoms were cleared at very low rates by copepods. Bacteria were cleared only by appendicularians (~170 to ~400 ml ind. -1 d -1 ) but not by any copepod, while heterotrophic protists constituted a substantial pro- portion in the diet of both copepods and appendicularians (~10 to 100% body carbon d -1 ), particularly during austral spring. Occasionally, copepod C-specific ingestion on heterotrophs was similar to that on autotrophic cells. Large ciliates and dinoflagellates were cleared but not ingested by the appen- dicularian O. dioica, suggesting a mechanism of trapping large cells in their houses and implying a rapid export of fresh material. Since heterotrophs are a common component in the diet of these 2 groups (omnivory by copepods and bacterophagy by appendicularians), they can potentially affect microbial food webs in this upwelling system and thus carbon export.