Table 2. — Stream, date of treatment, average concentration of TFM, 

 and period of exposure. Lakes Superior and Michigan, 1962-64 



Buck Bay Creek. . . 

 Gongeau Creek. — 



Iron River 



Sturgeon River^. . 



Do. 



Sunny Brook. . 

 Three Mile 



Creek 



Wilson Creek. 



Date of 

 treatment 



Period of 

 exposure 



May 5, 1964 

 Apr. 29, 1964 

 July 27, 1962 



(1) May 2, 1963 



(2) May 4, 1963 



(3) May 6, 1963 



(4) May 8, 1963 



(5) May 8, 1963 

 Apr. 20, 1963 



Apr. 17, 1964 

 Aug. 28, 1964 



3.8 

 6.0 

 3.4 

 2.3 

 2.3 



Hours 



2.8 



9.0 

 16.5 

 15.7 



7.0 

 16.1 



9.3 

 13.4 



6.7 



Numbers in parentheses refer to corresponding numbers of 

 locations on table 1; dates, concentrations, and exposure periods 

 reflect passage of chemical at each location as it moved down- 

 stream. 



^ Concentration included 2 percent by weight of Bayluscide. 



Limnephilida e 

 Molannidae 



Molanna 

 Leptoceridae 

 Lepidostomidae 



Lepidostoma 

 Brachycentridae 

 Helicopsychidae 



Helicopsyche 

 Lepidoptera 



Pyralididae 

 Coleoptera 

 Haliplidae 

 Dytiscidae 

 Gyrinidae 

 Elmidae 



Optioservns 



Stenelmis 



Dubiraphia 

 Helodidae 

 Chrysomelidae 



Donacia 

 Curculionidae 

 Diptera 

 Tipulidae 



Antocha 

 Simuliidae 

 Chironomidae 

 Heleidae 



Palpomia 

 Stratiomyiidae 

 Tabanidae 



Tabanus 

 Rhagionidae 



Atherix variegata 

 Empididae 

 Dolichopodidae 

 Muscidae 

 Hymenoptera 

 Thysanoptera 

 Thripidae 



OTHER INVERTEBRATES 

 Nematoda 

 Bryozoa 



Annelida 

 Crustacea 

 Cladocera 

 Copepoda 

 Isopoda 



Asellidae 

 Amphipoda 

 Gammaridae 

 Gammarus 

 Decapoda 

 Hydracarina 

 Mollusca 

 Gastropoda 

 Pelecypoda 



EFFECTS OF TREATMENT IN DIFFERENT 

 STREAMS 

 The effects of lamprey larvicides on aquatic 

 invertebrates were studied from a comparison 

 of bottonn samples taken before and at various 

 periods after treatment. Two pairs of treated 

 and control streams were studied, as were two 

 pairs of riffle and sand-detritus areas. The 

 treated-control series included Wilson Creek 

 and Little Garlic River (control) from Lake 

 Superior, and Three Mile Creek and Little 

 Scarboro Creek (control) from Lake Michigan. 

 Riffle and sand-detritus areas compared were 

 Iron River and Sturgeon River, and Gongeau 

 Creek and Buck Bay Creek. In addition a riffle 

 area of Sunny Brook was studied. 



Changes in Treated and Control Streams 



Samples were collected in riffle areas 1 day 

 before and 1 week after chemical treatment 

 of Wilson Creek, and on the same dates on 

 Little Garlic River, the untreated control 

 stream (table 1). The total number of organisms 

 in Wilson Creek 1 week after treatment was 

 40 percent of the pretreatment number (table 

 3). Of the organisms represented by 10 or 

 more individuals before treatment, 10 had 

 declined (Leptophlebiidae, Baetidae, Rhyaco- 

 philidae, Brachycentridae, Elmidae, Tipulidae, 

 Chironomidae, Heleidae, Annelida, and Hydra- 

 carina) and 1 had increased (Chloroperlidae). 



The total number of organisms in the con- 

 trol stream, Little Garlic River, changed 

 little after 1 week, and the composition of 

 organisms showed no clear major change. The 

 total number of organisms after 1 week was 

 104 percent of the first sample; of the orga- 

 nisms represented by 10 or more individuals, 

 6 declined and 6 increased. The changes in 

 total number of organisms in Little Garlic 

 River (control stream) and in Wilson Creek 

 (treated stream) showed no relation that would 

 indicate that the major reduction of inverte- 

 brates in Wilson Creek was not caused by the 

 treatment; decreases of some aquatic insects 

 may have been somewhat exaggerated, how- 

 ever, because of seasonal emergence. Lepto- 

 phlebiidae and Chironomidae declined in both 

 streams. 



