Effects of Lamprey Larvicides on Invertebrates 

 in Streams 



By 

 RICHARD L. TORBLAA, Fishery Biologist 



Bureau of Commercial Fisheries Biological Station 

 Marquette, Michigan 49855 



ABSTRACT 



The study was conducted on five streams tributary to Lake Superior and four 

 tributary to Lake Michigan, Samples of the bottom fauna before and after chemical 

 treatnnent revealed that most groups of aquatic organisms were not adversely af- 

 fected by exposure to larvicides. The total number of invertebrates was smaller 1 

 week after treatment than before treatment, increased somewhat by 6 weeks after 

 treatment, and had returned to pretreatment levels 1 year after treatnnent. Aquatic 

 insects were affected less than other organisms, and invertebrates were more se- 

 verely affected and recovered more slowly in areas of sand and detritus than in riffle 

 areas. 



INTRODUCTION 



A program to control the sea lamprey, 

 Petromyzon marinus , in the Great Lakes 

 with the lamprey larvicide TFM (3-trifluo- 

 romethyl-4-nitrophenol) began in 1958 (Apple- 

 gate, Howell, Moffett, Johnson, and Smith, 

 1961). In some treatments, 5,2'-dichloro-4' - 

 nitrosalicylanilide (Bayluscide^) was used as 

 a synergist with TFM to reduce cost (Howell, 

 King, Smith, and Hanson, 1964). The toxicity 

 of these compounds to several representative 

 groups of aquatic invertebrates has been tested 

 in the laboratory (Smith, 1967). The object of 

 the present study was to determine the effects 

 of these chemicals on aquatic invertebrates in 

 natural waters. 



MATERIALS AND METHODS 

 Streams were treated with TFMas described 

 by Applegate et al. (1961). One stream (Three 

 Mile Creek) was treated with a nnixture of 98 

 percent by weight TFM and 2 percent Bay- 

 luscide (Howell et al., 1964). 



Nine streams were selected for the study-- 

 five in the Lake Superior watershed and four 

 in the Lake Michigan basin. Of these, one 

 stream in each lake basin was an untreated 



^Registered trade mark of Farbenfabriken Bayer AG, 

 Leverkusen, West Germany. Mention of commercial prod- 

 ucts does not imply endorsement by the Bureau of Com- 

 mercial Fisheries. 



control. 1 made collections in control streams 

 on the same dates and in the same manner as 

 on treated streams. The great variations in 

 the physical and chemical characteristics of 

 the water of the streams (Zimmerman, 1968) 

 did not clearly influence the conclusions of this 

 study. The nature of the substrate, however, 

 influenced findings in different parts of a single 

 stream. 



Lake Superior streams sampled were Buck 

 Bay Creek, Gongeau Creek, Iron River, Little 

 Garlic River (control), and Wilson Creek; 

 Lake Michigan streams were Little Scarboro 

 Creek (control). Sturgeon River, Sunny Brook, 

 and Three Mile Creek. Three Mile Creek was 

 the only stream in this study treated with the 

 synergistic mixture of TFM and Bayluscide. 

 Study streams, chemical application sites, and 

 sampling sites are shown in figures 1 and 2, 

 Streams, locations, dates of collection, and 

 number of samples are given in table 1. 



All bottom samples were collected with a 

 modified Hess sampler (Waters and Knapp, 

 1961). 



Average concentrations of TFM for each 

 treatment were above minimum lethal con- 

 centration for larval lampreys (table 2). The 

 periods of exposure were the consecutive hours 

 above minimum lethal concentration. 



ORGANISMS COLLECTED AND IDENTIFIED 



I separated organisms fronn the debris by 

 a sugar flotation method (Anderson, 1959). Too 



