With climate change, oceans are becoming increasingly nutrient limited, favouring growth of prokaryotic picoplankton at the expense of the larger protist plankton whose growth support higher trophic levels. Constitutive mixoplankton (CM), microalgal plankton with innate phototrophic capability coupled with phagotrophy, graze on these picoplankton, indirectly exploiting the excellent resource acquisition abilities of the prokaryotes. However, feeding rates can be very low (e.g., a few bacteria d⁻¹). For the first time, the significance of such low consumption rates has been quantified. We find that while prokaryote-carbon (C) supply to CM grown at non-limiting light was so low that it may appear insignificant (< 10%), contributions of nitrogen (N) and phosphorus (P) from ingestions of 1–12 prokaryotes d⁻¹ were significant. Under limiting light, contributions of ingested C increased, also raising the contributions of N and P. The order of nutritional importance for CM growth from predation was P > N > C. Further, provision of N through internal recycling of ingested prey-N stimulates C-fixation through photosynthesis. Importantly, coupled photo-phago-mixoplanktonic activity improved CM resource affinities for both inorganic and prey-bound nutrients, enhancing the nutritional status and competitiveness of mixoplankton. With warming oceans, with increased prokaryote abundance, we expect CM to exhibit more phagotrophy.

随着气候变化，海洋变得越来越缺乏营养，有利于原核微型浮游生物的生长，而牺牲了支持更高营养水平生长的更大的原生生物浮游生物。本构混合浮游生物 (CM) 是一种具有先天光养能力和吞噬能力的微藻浮游生物，以这些微型浮游生物为食，间接利用了原核生物出色的资源获取能力。然而，喂养率可能非常低（例如，一些细菌d ^-1）。如此低的消耗率的重要性首次被量化。我们发现，虽然在非限制光下生长的 CM 的原核生物碳 (C) 供应量非常低，以至于看起来微不足道 (< 10%)，但摄入 1-12 的氮 (N) 和磷 (P) 的贡献原核生物d^-1显着。在限制光下，摄入的 C 的贡献增加，同时增加了 N 和 P 的贡献。捕食对 CM 生长的营养重要性顺序为 P > N > C。此外，通过摄入的猎物 N 的内部循环提供 N 刺激通过光合作用进行 C 固定。重要的是，耦合的 photo-phago-mixoplanktonic 活动提高了 CM 资源对无机和猎物结合营养素的亲和力，提高了 mixoplankton 的营养状况和竞争力。随着海洋变暖和原核生物丰度的增加，我们预计 CM 会表现出更多的吞噬作用。