Table 1.
Main elements of T. elongata’s diet across the focal streams. Streams are presented from low to high DOC concentrations. Dominant prey taxa are those that made up >70% biomass in the web. Taxa in italics were not analyzed for MeHg concentration due to low (<20 mg) biomass.
| Stream | Year | # spider webs | # insects from webs | Mean ± 1 SE # insect/web | Mean ± 1 SE biomass/web | Dominant prey taxa by mass |
|---|---|---|---|---|---|---|
| Beck Brook | 2011 | 11 | 149 | 13.1 ± 9.9 | 3.0 ± 1.5 | Chironomidae (58%) |
| Tipulidae (28%) | ||||||
| 2012 | 32 | 92 | 2.7 ± 0.4 | 1.4 ± 0.4 | Tipulidae (42%) | |
| Chironomidae (34%) | ||||||
| Bartlett Brook | 2011 | 6 | 19 | 3.0 ± 0.7 | 2.4 ± 1.0 | Ephemerellidae (79%) |
| 2012 | 40 | 133 | 3.3 ± 0.5 | 1.1 ± 0.3 | Chironomidae (63%) | |
| Tipulidae (19%) | ||||||
| Blodgett South | 2011 | 7 | 21 | 3.0 ± 1.0 | 1.0 ± 0.6 | Leuctridae (52%) |
| Chironomidae (44%) | ||||||
| 2012 | 27 | 114 | 4.0 ± 0.9 | 1.5 ± 0.3 | Chironomidae (44%) | |
| Tipulidae (34%) | ||||||
| Otter Pond | 2011 | 3 | 11 | 3.0 ± 2.0 | 0.9 ± 0.4 | Chironomidae (100%) |
| 2012 | 29 | 222 | 7.6 ± 2.3 | 2.0 ± 0.6 | Chironomidae (65%) | |
| Hydropsychidae (29%) | ||||||
| Pike Brook | 2011 | 6 | 18 | 2.7 ± 0.6 | 2.8 ± 1.7 | Tipulidae (63%) |
| 2012 | 42 | 258 | 6.0 ± 1.5 | 3.2 ± 0.9 | Heptageniidae (46%) | |
| Chironomidae (36%) | ||||||
| Kidder Brook | 2011 | 13 | 200 | 15.1 ± 8.2 | 3.3 ± 1.4 | Chironomidae (70%) |
| 2012 | 42 | 193 | 4.5 ± 0.9 | 2.5 ± 1.1 | Ephemerellidae (41%) | |
| Chironomidae (25%) | ||||||
| Leuctridae (18%) | ||||||
| King Hill | 2011 | 8 | 10 | 1.25 ± 0.2 | 0.6 ± 0.17 | Leptohyphidae (35%) |
| Tipulidae (28%) | ||||||
| Chironomidae (19%) | ||||||
| 2012 | 35 | 132 | 3.5 ± 0.6 | 2.0 ± 0.5 | Heptageniidae (18%) | |
| Chironomidae (17%) | ||||||
| Leuctridae (15%) | ||||||
| Tipulidae (10%) | ||||||
| Perlodidae (9%) | ||||||
| Blodgett North | 2011 | 6 | 19 | 3.2 ± 1.4 | 0.9 ± 0.5 | Chironomidae (97%) |
| 2012 | 35 | 170 | 4.7 ± 1.2 | 1.8 ± 0.7 | Chironomidae (41%) | |
| Perlodidae (39%) | ||||||
| Red Water Creek | 2011 | 10 | 44 | 4.4 ± 0.8 | 5.0 ± 2.2 | Zygoptera (45%) |
| Ephemeroptera (27%) | ||||||
| 2012 | 30 | 102 | 3.3 ± 0.5 | 1.9 ± 0.5 | Chironomidae (32%) | |
| Leptophlebiidae (17%) | ||||||
| Heptageniidae (17%) | ||||||
| Tipulidae (16%) | ||||||
| Herrick Cove | 2011 | 13 | 57 | 4.3 ± 1.1 | 1.4 ± 0.4 | Chironomidae (96%) |
| 2012 | 35 | 102 | 2.8 ± 0.3 | 1.2 ± 0.2 | Chironomidae (60%) | |
| Hydropsychidae (18%) |
Numbers inside parenthesis represent contribution to spider diet. Collections were performed during the last week of June 2011, the second and third weeks of May 2012, and the third weeks of June and July 2012.