Table 1.
Hydroperiod (length of aquatic phase) and physical-chemical data for each pond.
Fig 1.
Ordination plot for 2008 showing variation in food-web structure (n = 4 variables, black arrows) in response to environmental variation (n = 4 variables, grey arrows) summarized by redundancy analysis (RDA).
Sampling sites are denoted by black outlined grey circles. MaxTP is the trophic position of the top predator or realized food-chain length, TAfoodweb is the total area encompassed by all species in δ13C–δ15N bi-plot space. Plot used scaling = 1 to create a distance biplot where objects approximate their Euclidean distances in the space of response variables. Length of the arrow represents the strength of the gradient. Arrows that are directed in opposite directions are negatively correlated. The angles between environmental and food-web variables reflect their correlations.
Fig 2.
Canonical correspondence analysis (CCA) ordination biplots showing the association between the presence-absence of invertebrate families and environmental predictors in (A) 2008 and (B) 2009.
(A) Four environmental predictors in 2008 measured in seven ponds and (B) seven environmental variables from nine ponds in 2009. The direction of the arrow indicates direction of maximum change and the length is proportional to the rate of change of that variable. See S1 Table for full invertebrate family names.
Fig 3.
Redundancy Analysis (RDA) tri-plot illustrating the relationship between environmental variables (n = 4, grey arrows), food-web metrics (n = 4, black arrows), and ponds (n = 9, black outlined grey dots) in 2009.
Pond name is placed adjacent to dot.
Fig 4.
RDA tri-plot displaying food-web structure (black arrows) in relation to six environmental variables (grey arrows, excluding hydroperiod) and nine ponds (black outlined grey dots) in 2009.
Table 2.
Results from Correspondence Analysis (CA) on the invertebrate and amphibian assemblages (presence-absence data).
Table 3.
Eigenvalues, percentage of variation explained, and permutation test statistics from Canonical Correspondence Analysis (CCA) of invertebrate and amphibian assemblages and environmental data from ponds in Southeastern Ontario, Canada.
Fig 5.
Canonical correspondence analysis (CCA) biplots showing the association of amphibian species presence-absence and A) four environmental predictors in 2008 from seven ponds and B) five environmental variables in 2009 collected from eight ponds.
Species placement in biplot is marked with an open circle. MeanCanopy is the mean canopy cover, meanArea is the mean pond area (m2) measured over the ponds duration, CVdepth is the coefficient of variation of water depth, DO is dissolved oxygen, and CVtemp is the coefficient of variation of water temperature.