Temperature and Nutrient Effects on Organic Exudate Production in Lingulaulax polyedra (Stein) Head et al., 2024 Cultures

Transparent Exopolymer Particles (TEP) play a key role in the marine carbon cycle, facilitating the aggregation and exportation of organic matter. TEP production is particularly relevant during Harmful Algal Blooms (HABs), where dinoflagellates like Lingulaulax polyedra can release significant amounts of exudates. Temperature is a crucial environmental factor that influences HAB dynamics and physiological processes of bloom-forming species, affecting exudate composition and abundance. This study investigates the influence of temperature and nutrient availability on the production of organic exudates in L. polyedra cultures. TEP, Particulate Organic Carbon (POC), and Particulate Organic Nitrogen (PON) concentrations were analyzed under controlled laboratory conditions. Batch cultures were maintained at temperatures of 17, 20, and 25 °C, with two nutrient regimes (low and high nitrate and phosphate concentrations). Exudates were quantified using colorimetric and spectrophotometric methods. We found that temperature and nutrient availability significantly influence exudate production. The highest TEP concentration was recorded at 25 °C in cells cultivated under low-nutrient conditions, whereas POC exhibited a notable increase at 20 °C. ANOVA revealed that TEP and POC were the primary drivers of variability among treatments. These findings reveal that temperature is important in the regulation of L. polyedra exudate production. The role of this variable on organic matter cycling and bloom dynamics in marine ecosystems is discussed.