Abstract:
The shallow water benthic habitat of the SW Beaufort Sea is frequently
gouged by the keels of ice pressure ridges. This natural physical
disturbance was hypothesized to be an important factor affecting the
structure of the benthic community. Smith-McIntyre grab samples were
taken from three discrete gouge axes and from control areas on both
sides of each gouge to examine this hypothesis. Significantly lower
abundances were noted for total macrofauna and at the major taxa level
inside two of the three gouge axes. Diversity and evenness indices
increased inside the axes of all three gouges. At the species level,
differences existed between gouge areas, but in general lower
abundances were also found for many of the dominant species. A few
species abundances were significantly higher inside the gouge axes.
These differences were not dependent on differences in gouge depth,
age or associated sediment parameters. Thus ice gouging is thought to
be important in structuring the associated benthic assemblages at these discrete disturbance sites. The generality of the significance
of ice gouging along the entire Beaufort coast is considered.
Comparisons among gouges by cluster analyses of both the
species and sediment data each yielded three groups of similar station
aggregations suggesting a strong correlation between species
distributions and sediment characteristics. However, factors such as
water depth and relative gouge age, also correlate with the observed
cluster groups. Therefore, one factor alone was unable to account for
the observed patterns. Interactions of the many physical factors in
this environment are proposed to explain the observed distributions.
The physical action of ice gouging directly impacts the benthic
assemblages by reducing abundances and indirectly by changing the
associated sediment parameters which can influence animal
distributions.
