Publication Date:
2017-01-31
Description:
Stones released by melting icebergs are called dropstones, and these stones constitute
island-like hard-bottom habitats at high latitudes. In 2012, dropstone megafauna in the
HAUSGARTEN observatory in the Fram Strait was sampled photographically. We tested the
hypothesis that dropstones would have the same species distribution patterns as terrestrial
islands, using 5 patterns commonly found in the classical island literature. Higher richness, diversity,
and abundance of fauna occurred on larger stones and on stones near a deep-water rocky
reef. These patterns can be explained by the greater surface area of larger stones, the exposure of
larger stones to faster current higher in the benthic boundary layer, and increased larval supply
from the rocky reef. Some pairs of morphotypes (12 pairs out of 56 morphotypes and 1540 possible
pairs) co-occurred less often than expected by chance. While similar patterns have been attributed
to interspecific competition in the classical island literature, we offer alternative mechanisms for
dropstones. Non-random co-occurrence on dropstones may be explained by larval dispersal.
Dropstone fauna had an overdispersed (clumped) distribution, so pairs of morphotypes may have
negative non-random co-occurrence simply because short larval life and limited dispersal ability
prevent them from having randomly overlapping distributions. In addition, we found 8 morphotype
pairs that co-occurred more often than expected by chance because of epibiontism. The patterns
found in dropstone communities resemble terrestrial islands, but different mechanisms may
be responsible.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
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