Appendix A. Additional description of the study system.
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| FIG. A1. Map of Kickapoo State Park. Kickapoo State Park (40.14°N, 87.74°W) is located in east central Illinois, USA (inset). The park includes a number of lakes recently created from abandoned strip mines. Eight of these lakes are included in this study: a) Sportsman's Lake, b) Emerald Lake, c) Inland Sea, d) Clear Lake, e) High Lake, f) Long Lake, g) Deep Lake, and h) Number 6 Lake. The six light blue lakes were formed in the 1920s, and the two dark blue lakes were formed in the 1950s. Deep lakes: Sportsman's, Clear, Deep. Moderate-depth lakes: Long, High, Inland. Shallow lakes: Emerald, Number 6. |
TABLE A1: Physical characteristics and colonization years of Kickapoo State Park lakes. Origin date is the year water was allowed to fill in the lake basin. Colonization year is estimated for each cladoceran taxon recoverable from the sediment cores. Because high sedimentation rates would have likely resulted in difficulties obtaining exact sediment ages via gamma spectroscopy, we based colonization years on the assumption of equal sedimentation rate through time within each lake. Although sedimentation rates likely decreased as the surrounding terrestrial communities developed, these estimates do provide relative dates that can be used to distinguish among rapidly colonizing species vs. those that colonized much later. Daphnia ambigua and D. parvula ephippia were not distinguishable from one another and thus are grouped together. A cliff was pushed into Long Lake disrupting, the assumption of equal sedimentation rate over time. Therefore, its colonization sequence is provided.
| Lake | Surface Area (ha) | Max Depth (m) | Stratification Category | Origin Date | Ceriodaphnia reticulata | Daphnia ambigua / parvula | Daphnia dentifera | Daphnia pulicaria |
| #6 | 4.2 | 5 | Shallow | 1927 | 1968 | 1928 | 1980 | 1949 |
| Clear | 14.6 | 16 | Deep | 1926 | 1928 | 1926 | 1987 | 1996 |
| Deep | 0.8 | 12 | Deep | 1959 | 1969 | 1980 | 1985 | 1971 |
| Emerald | 1.3 | 4 | Shallow | 1926 | 1964 | 1926 | 1963 | 1959 |
| High | 3.5 | 7 | Moderate | 1926 | 1950 | 1939 | 1967 | 1998 |
| Inland | 7.9 | 8 | Moderate | 1926 | 1927 | 1927 | 1927 | 1931 |
| Long | 20.7 | 9 | Moderate | 1927 | 1 | 1 | 3 | 4 |
| Sportsman's | 14.4 | 16 | Deep | 1953 | 1954 | 1954 | 1963 | 1966 |
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| FIG. A2. Summer stratification regime of Kickapoo State Park lakes. Summer dissolved oxygen (squares) and temperature (diamonds) profiles. Means are July-August averages from 2003, 2004 and 2009. Error bars are one standard error and include both with and among year variation. Depth profiles do not extend to the deepest point of Clear and Sportman's lakes due to the maximum depth exceeding the length of the cable. Note differences in depth axes among lakes. Based on previous research demonstrating the effect of thermal structure on the composition of zooplankton assemblages (Tessier and Welser 1991, Tessier and Woodruff 2002), we categorized lakes a priori into three groups: shallow unstratified lakes, deep stratified lakes with a well-formed hypolimnion, and moderate depth lakes with a relatively small hypolimnion. |
LITERATURE CITED
Tessier, A. J. and J. Welser. 1991. Cladoceran assemblages, seasonal succession and the importance of a hypolimnetic refuge. Freshwater Biology 25:85–93.
Tessier, A. J. and P. Woodruff. 2002. Cryptic trophic cascade along a gradient of lake size. Ecology 83:1263–1270.