Figure 1.
Map of 2012 sampling locations in Oneida Lake.
Each nearshore site (stars) included quantitative samples at 0.1–0.3 m, 0.5 m, and 1 m depths and a qualitative sample. The inset gives site locations in Lower South Bay from which samples were collected in 1917, 1967, 1992, and in 2012, and used in the historical analysis of the mollusc community.
Table 1.
Long-term data on species richness (exotic species richness in parenthesis), density (1915–2012, m−2± standard error), and biomass (g m−2, ± standard error, lakewide 2012 only) of Oneida Lake molluscs in Lower South Bay (LSB) and lakewide (LW).
Figure 2.
Species richness and density of molluscs at different depths in 2012 in Oneida Lake.
Error bars indicate standard error.
Table 2.
Average (± standard error) mollusc species richness, density (m−2), and biomass (g m−2) across different substrates.
Figure 3.
Density-based comparisons of mollusc community in Lower South Bay.
A: k-dominance curve of the gastropod assemblage found in Lower South Bay in 1917, 1967, and 2012 based on species abundances across all samples in each study. B: Cluster analysis (group average) built on Bray-Curtis similarity matrix of average yearly gastropod densities. Black solid lines are significant at P = 0.002 (SIMPROF test).
Figure 4.
NMDS ordination plots of the molluscan community in Lower South Bay.
Structure of the total molluscan community (A), gastropod (B) and bivalve (C) assemblages based on Bray-Curtis similarities of species presence-absence in samples collected in the Lower South Bay of Oneida Lake collected in 1917 [22], [23], 1967 [24], and 2012. The circled points in (A) and (B) represent 33 samples from 1967 in which only B. tentaculata was found.
Figure 5.
Long term changes in the mollusc community and lakewide limnological parameters.
A: Gastropod and unionid species richness (bars) and gastropod average density (± standard error, where available) in Lower South Bay in 1917 [23], 1967 [24], and 2012 (our study). B: Growing season (May-October) values of total phosphorus, chlorophyll a, and Secchi depth in Oneida Lake from 1927 to 2011, averaged across 5-year periods. Where available, error bars indicate standard deviation of annual growing season averages. Vertical dashed line indicates timing of D. polymorpha invasion. Data from Muenscher [73], Greeson [74], and Rudstam [29].