Seasonal variation in floating persistence of detached Durvillaea antarctica (Chamisso) Hariot thalli

• Published in: Botanica Marina
• Main Authors: Graiff, Angelika, Karsten, Ulf, Meyer, Steffi, Pfender, David, Tala, Fadia, Thiel, Martin
• Format: Article in Journal/Newspaper
• Language: English
• Published: Walter de Gruyter GmbH 2012
• Subjects: Antarc*; Antarctica
• Online Access: http://dx.doi.org/10.1515/bot-2012-0193; https://www.degruyter.com/document/doi/10.1515/bot-2012-0193/xml; https://www.degruyter.com/document/doi/10.1515/bot-2012-0193/pdf

Abstract Several large kelp species are capable of long-distance dispersal via rafting. However, seasonal changes in environmental conditions at the sea surface may variably affect the physiological status of the floating thalli; challenging conditions during summer may accelerate disintegration and cause rapid sinking. We used the bull kelp Durvillaea antarctica from northern-central Chile (30°S) to test seasonal variation in floating persistence. Experiments with tethered specimens were conducted in all seasons to assess how variable environmental conditions influence the morphology and photosynthetic characteristics of floating D. antarctica . Floating specimens stayed afloat at the surface for more than 1 month during moderate environmental conditions that prevailed in winter, spring, and fall. However, higher water temperatures and intense solar radiation in summer resulted in significant biomass losses and rapid disintegration of the floating kelps; consequently, they sank within <1 month. These strong seasonal effects were reflected in decreasing maximal quantum yield as well as in maximum relative electron transport rates of photosynthesis. Understanding physiological responses of floating algae is important because increasing global temperatures and shifts in solar radiation may strongly affect the survival of floating algae, potentially reducing the distances and frequencies of rafting dispersal.