Hydrological connectivity influences the aquatic metacommunity structure of an Arctic delta floodplain

Hydrological connectivity is fundamental determinant of aquatic
metacommunity structure, but the potential response to altered patterns of
connectivity in a changing climate remain poorly understood, particularly
in regards to vulnerable systems such as Arctic deltaic lakes. Here we
present the first study to examine the metacommunity structure of aquatic
invertebrates in a major Arctic floodplain system (Mackenzie Delta,
Northwest Territories). We sampled macroinvertebrate communities across
the longitudinal span of the Delta and utilized three complementary
techniques (variance partitioning, elements of metacommunity structure,
and fourth corner analysis) to determine the relative influence of
environmental versus spatial variation, metacommunity structure across
dispersal modes, and the functional metacommunity structure. Environmental
factors explained the most variation (23%) compared to spatial factors
(2%) or environmental/spatial covariance (4%). Functional structure was
primarily related to dispersal mode and lake isolation, with distributions
of aerial dispersers determined mainly by environmental factors and
aquatic dispersers by both dispersal limitation and environmental factors.
We attribute these results to the inter-lake mixing effects of annual
flooding and the lack of barriers to aerial dispersal, and discuss how a
loss of aquatic invertebrate biodiversity could result from projected
climate-mediated alterations to ice jam dynamics in the Delta.