We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Contrasting Sea‐Ice Algae Blooms in a Changing Arctic Documented by Autonomous Drifting Buoys.
- Authors
Hill, Victoria; Light, Bonnie; Steele, Michael; Sybrandy, Andrew Lowy
- Abstract
Novel observations of the seasonal evolution of an ice algal bloom on the Chukchi shelf were collected by two autonomous buoys deployed 180 km apart in first‐year drifting sea ice. High attenuation of blue light in the bottom of the ice indicated considerable accumulation of ice algae biomass with derived Chlorophyll‐a concentrations (Chl a) up to 184 mg m−2. Differences in the magnitude and persistence of ice algae biomass under each buoy appear to have been driven by differences in snow thickness, as ice thickness was similar between the sites. Minimal snow cover (0.02 m) around one buoy was associated with algae growth beginning in mid‐May and lasting 70 days. The second buoy had notably more snow (0.4 m), causing ice algae production to lag behind the first site by approximately 4 weeks. The delay in growth diminished the peak of ice algae Chl a and duration compared to the first site. Light attenuation through the ice was intense enough at both buoys to have a potentially inhibiting impact on water column phytoplankton Chl a. Modeling ice algae growth with observed light intensities determined that nutrients were the limiting resource at the low snow site. In contrast, the algae at the high snow site were light‐limited and never nutrient‐limited. These data point toward changes in ice algae phenology with an earlier and longer window for growth; and nutrients rather than light determining the longevity and magnitude of production. Plain Language Summary: Ice algae growing on the underside of Arctic sea ice require light and nutrients. Light levels are enhanced beneath sea ice that is thinner and has less snow accumulation, creating a favorable environment for algal growth. This study describes results from two autonomous instrument systems installed in Arctic sea ice in March 2018. Sensors measured the amount of light transmitted through the ice and snow. Changes in the light were connected to changes in the magnitude of algae present. One site had 0.02 m of snow, and the other had 0.4 m; ice thickness was similar between the sites. Ice algae appeared in mid‐May at the low‐snow site, growth at the high‐snow site began 4 weeks later. Numerical modeling showed that algae at the low snow site had abundant light, with growth limited by nutrients. In comparison, light was the limiting resource at the high snow site. Additionally, absorption of light by ice algae reduced the growth of water column phytoplankton under the ice. These data show that as snow cover is reduced on sea ice, ice algae could start growing earlier in the season and reach higher concentrations. Key Points: Autonomous buoys captured the seasonal evolution of ice algae growth in first‐year Arctic sea ice, bloom initiation determined by snow depthEarly bloom onset and 70‐day growth window were observed, evidence that shifts in phenology projected by climate models have occurredNutrients limited ice algae growth; movement of the ice promoted turbulent diffusion of nutrients supporting high biomass
- Subjects
ARCTIC regions; ALGAL blooms; SEA ice drift; TOXIC algae; SEA ice; ALGAL growth; ATTENUATION of light; SNOW accumulation
- Publication
Journal of Geophysical Research. Oceans, 2022, Vol 127, Issue 7, p1
- ISSN
2169-9275
- Publication type
Article
- DOI
10.1029/2021JC017848