Victoria Rebbeck

Session
Session 3
Board Number
73

Snow Algae Response to Nutrient Enrichment

Snow algae are a specialized algae that live in cold conditions (around 0°C) predominantly on supraglacial and mountain snow. Some species of algae that produce astaxanthin are colloquially referred to as watermelon snow as they often make snow appear a red color. Snow algae require liquid water and light so they reside primarily on top of snow. Snow algae contribute to biogeochemical cycling though altering the albedo or reflectiveness of a surface. When snow algae grow on the surface of snow, they reduce albedo and increase melt. Snow algae produces both chlorophyll, which makes a green color, and carotenoids, which produce a red color (Hoham & Remias, 2020). As agricultural activity and urbanization increase, nitrogen and phosphorus deposition will also increase the concentration of these key nutrients in snow. While initial studies have shown blooms of algae occur with an N:P ratio from 11-20 on snow (Spijkerman et al., 2012), it is largely unknown how nitrogen and phosphorus inputs will impact snow algae growth and thus their impact on albedo and melt. This experiment characterized the response of snow algae to a variety of NP ratios. Chlamydomonas yellowstonensis and Chlamydomonas sp. were grown in media in a variety of NP ratios at 5°C and 9°C in triplicate for 30 days. Cell concentrations were determined after 4, 8, 12, 16, 20 and 30 days after initial inoculation using a hemocytometer. The cells responded positively to the increase in N concentration and growth rates were lower at 5°C compared to 9°C. These results contradict the initial hypothesis that snow algae, even in a lab setting, prefers cold conditions; and supports the hypothesis that snow algae respond positively to nitrogen addition. These results help create a better understanding of how snow algae will impact ecosystems where nitrogen deposition is increasing.