Abstract

Pulse feeding and growth of the Black Sea strain of dinoflagellates Oxyrrhis marina (Dujardin, 1841) (OXY–IBSS), equivalent spherical diameter (ESD) (23.5 ± 3.1 μm) have been studied under experimental conditions simulating phytoplankton blooms. Microalgae Phaeodactylum tricornutum (P, ESD 3.4 ± 0.3 μm), Isochrysis galbana (I, ESD 3.7 ± 0.4 μm), Tetraselmis suecica (T, ESD 6.1 ± 0.9 μm), and Rhodomonas salina (R, 7.4 ± 0.7 µm) were used as food objects in a one-component and three-component suspensions. Microalgae concentrations (∼10⁶ cells/mL for T and R; up to ∼4 × 10⁶ cells/mL for P and I) were chosen to ensure their equal total carbon biomass ∼0.02 μg C/μL in the food mixtures at the beginning of the experiment. Under ad libitum conditions, the maximum clearance rates of the OXY–IBSS reached 0.1–0.5 μL ind./day, and the grazing rate of microalgae was 34–44 cells/(ind h) for P and I, and 2–11 cells/(ind. h) for R and T, respectively. The grazing rate of microalgae in carbon units was significantly higher when feeding on I (3.9 ng C/(ind. day)) and significantly less when fed with a mixture of microalgae TRP (1.5 ng C/(ind. day)). Maximum abundance of OXY–IBSS, achieved within 3 or 4 days (by the time the microalgae concentration decreased below threshold), varied from 19 × 10³ ind./mL (P) to 43 × 10³ ind./mL (I). In the absence of food, dinoflagellates O. marina turned to cannibalism, and within 4 days the oscillating fluctuations (within 50%) in their number took place. Although the specific population growth rate (μ, day^-1) of OXY–IBSS was higher when feeding on small cells (∼2 days^–1 on I), the gross growth efficiency (GGE) of OXY–IBSS was significantly higher when fed on large (T and R) microalgae (26–29% vs. 14–15%). At lower daily rations (DRs) when fed with the mixture TRP, the GGE of OXY–IBSS was significantly higher (41%) when compared to other nutritional conditions. The feeding strategy of opportunistic predator O. marina on diverse (in terms of size and chemotaxonomic characteristics) mixtures of prey lay in a flexible choice between high specific population growth rate, or high gross growth efficiency, that obviously gives the populations of this species the advantages over other protists under conditions of the pulsed phytoplankton blooms.

中文翻译：

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豆类喂养和豆类生长：异养甲藻的高度适应性策略 Oxyrris marina

摘要

在模拟浮游植物繁殖的实验条件下，研究了黑海甲藻Oxyrris marina菌株（Dujardin，1841）（OXY-IBSS）的脉冲摄食和生长，等效球径（ESD）（23.5 ± 3.1 μm）。使用微藻三角褐指藻( P , ESD 3.4 ± 0.3 μm)、等鞭金藻( I, ESD 3.7 ± 0.4 μm)、Tetraselmis suecica ( T, ESD 6.1 ± 0.9 μm) 和红单胞菌(R, 7.4 ± 0.7 μm)作为单组分和三组分悬浮液中的食品。选择微藻浓度（T和R为~10 ^{6 个}细胞/mL ； P和I高达~4 × 10 ^{6 个}细胞/mL ）以确保它们在食物混合物中的总碳生物量相等~0.02 μg C/μL。实验开始。在自由采食条件下，OXY-IBSS的最大清除率达到0.1-0.5 μL ind./day，微藻的捕食率P和I为34-44个细胞/(ind h)， 2-11个细胞/(ind.h)分别表示R和T。当喂食I时（3.9 ng C/（标准天）），碳单位中微藻的放牧率显着较高，而当喂食微藻TRP混合物时（1.5 ng C/（标准天））则显着降低。OXY-IBSS 的最大丰度在 3 或 4 天内达到（当微藻浓度降至阈值以下时），变化范围为 19 × 10 ³ ind./mL ( P ) 至 43 × 10 ³ ind./mL ( I ) 。在缺乏食物的情况下，甲藻O. marina开始同类相食，并且在4天内其数量发生了振荡波动（50%以内）。虽然当以小细胞为食时，OXY-IBSS 的特定群体增长率（μ，第^-1天）较高（I上~2 天^–1），但当以小细胞为食时，OXY-IBSS 的总生长效率（GGE）显着更高大型（T和R）微藻（26-29% vs. 14-15%）。在较低的每日日粮 (DR) 下，当饲喂混合物TRP 时， OXY-IBSS 的 GGE 显着高于其他营养条件 (41%)。机会性捕食者O. marina的摄食策略在不同的（在大小和化学分类学特征方面）猎物混合物上，存在于高特定种群增长率或高总生长效率之间的灵活选择，这显然使该物种的种群在脉冲条件下比其他原生生物具有优势。浮游植物大量繁殖。