Photosynthetic and nutritional plasticity in mixotrophic dinoflagellates: responses to environmental change.

Mixotrophic dinoflagellates, which combine photosynthesis with heterotrophic feeding, exhibit remarkable nutritional flexibility that enables them to thrive in diverse and often suboptimal marine environments. This dual strategy allows dynamic adjustment to fluctuating conditions such as low light, inorganic nutrient limitation, and prey scarcity. Ecologically, mixotrophic dinoflagellates occupy a distinctive position, functioning simultaneously as primary producers and consumers. By linking microbial and classical food webs, they contribute to nutrient recycling, energy transfer, and food web stability. Their capacity to access multiple resource pools enhances ecosystem productivity and resilience under environmental variability. From an evolutionary perspective, mixotrophy has contributed significantly to the diversification and ecological success of dinoflagellates, particularly in nutrient-stratified marine systems. It has facilitated adaptations in cellular organization, metabolic pathways, and behavioral strategies that broaden ecological niches. In this review, we synthesize recent advances in understanding the physiological and ecological dimensions of dinoflagellate mixotrophy. We focus on how environmental drivers - including light availability, nutrient supply, prey abundance, and temperature - regulate the balance between photoautotrophic and heterotrophic modes. This insight into the regulatory mechanisms of mixotrophy offers a broader understanding of how dinoflagellates respond to environmental change and how they may shape future marine ecosystems.