Polar coralline algal CaCO3-production rates correspond to intensity and duration of the solar radiation

[摘要] In this study we present a comparative quantification of CaCO₃production rates by rhodolith-forming coralline red algal communitiessituated in high polar latitudes and assess which environmental parameterscontrol these production rates. The present rhodoliths act as ecosystemengineers, and their carbonate skeletons provide an important ecologicalniche to a variety of benthic organisms. The settings are distributed alongthe coasts of the Svalbard archipelago, being Floskjeret (78°18' N)in Isfjorden, Krossfjorden (79°08' N) at the eastern coast ofHaakon VII Land, Mosselbukta (79°53' N) at the eastern coast ofMosselhalvøya, and Nordkappbukta (80°31' N) at the northerncoast of Nordaustlandet. All sites feature Arctic climate and strongseasonality.

The algal CaCO₃ production rates were calculated from fuchsine-stained,presumably annual growth increments exhibited by the rhodoliths and rangefrom 100.9 g (CaCO₃) m⁻² yr⁻¹ at Nordkappbukta to 200.3 g(CaCO₃) m⁻² yr⁻¹ at Floskjeret. The rates correlate tovarious environmental parameters with geographical latitude being the mostsignificant (negative correlation, R² = 0.95, p = 0.0070), followed by theduration of the polar night (negative correlation, R² = 0.93, p = 0.0220),the duration of the sea ice cover (negative correlation, R² = 0.87,p = 0.0657), and the annual mean temperature (positive correlation,R² = 0.48, p = 0.0301).

This points out sufficient light incidence to be the main control of thegrowth of the examined coralline red algal rhodolith communities, whiletemperature is less important. Thus, the ongoing global change with itsrising temperatures will most likely result in impaired conditions for thealgae, because the concomitant increased global runoff will decrease watertransparency and hence light incidence at the four offshore sites. Regardingthe aforementioned role of the rhodoliths as ecosystem engineers, the impacton the associated organisms will presumably also be negative.

[学科分类] 地球化学与岩石