Transcript Different ice algal communities

Microalgae - definitions
ICE ALGAE
PHYTOPLANKTON
Microalgae that live within the
sea ice attached to ice crystals,
or associated with the
undersurface of the ice as
floating mats, lumps, or strands
that extend downward into the
water column.
Microalgae that float aimlessly
or swim too feebly to maintain a
constant position against a
water current.
In addition, there are microalgae that live within the
sediment or associated with the surface of the ocean
floor, as well as on marine vegetation and animals.
Not only do morphological characteristics vary, but also physiological characteristics
may vary within a species. A better understanding of the species composition may
therefore improve the knowledge also about ecology and physiology of species as well
as interactions and processes in the ecosystem.
Some species may indicate the condition of the ecosystem (indicator species).
C. H. von Quillfeldt, Norwegian Polar Institute
Diversity reflects
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Habitat:
Types of habitats:
- Sea ice
– Important factors:
• Age
• Construction
• Degree of motion
• Snow on top
- Water column
- Ocean floor
- Other organisms
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Season
Environmental conditions
- Dependent on locality
Annual cycle and north south gradient
Modified from Syvertsen (1991)
– Deep ocean – coast
- Different requirements among species
- Variations between years
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Geography
- Classification according to affinity to
the coast or to water masses :
- Oceanic, neritic or littoral species
- Circumpolar, bipolar and/or disjunct species
- Cosmopolitian, cold/warm or temperate species
As the season advance the algae will
disappear from the underside of the ice
Distribution: Predominant influencing factors: Size of the cells (0.2-2000 m), passive transport,
living in the euphothic zone and rapid vegetative growth (0.2-2 divisions/24 hours).
Ice drift and ocean currents cause comparable species composition over huge areas in the Arctic.
C. H. von Quillfeldt, Norwegian Polar Institute
Example: Different ice algal communities
Modified from Syvertsen (1991)
Melt pond
community
Band
community
Sub-ice communities
Central Arctic Ocean: Water column suffer from light limitation by multi-year ice, making ice
algae the most important contributor of the annual primary production.
C. H. von Quillfeldt, Norwegian Polar Institute
Factors influencing on
diversity results
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Snapshot
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Sampling in an area:
• Not continuously sampling throughout the year
• Visited different time from year to year
• It is likely to be interannual differences
Patchy distribution (horizontal and vertical)
Sampling methods
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Example – identification
Ice cores
• Sub-ice community lost
– Divers necessary
Phytoplankton net
• Mesh size
• Actual depth sometimes difficult to know
Water bottles
Sediment cores
• Separating sections – some species may be lost
Preservation
• Different needs for different algal groups
Identification
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Fossula arctica
Often dominant in ice algal communities
and early phytoplankton blooms in the
Arctic.
Misidentifications in the literature
Described: 1996
Identified as similar species from other areas
Before that misidentified!!!
Only referred to by their genus name
Have changed name
Some are impossible to separate unless resting spores are present
Described as a number of different species: polymorphic stages of a single species
Some are not yet described
C. H. von Quillfeldt, Norwegian Polar Institute