Mortality in Unionacean Mussels in a Year of Drought

Abstract

In the year 1980 drought prevailed in south-central Kansas causing desiccation of shallower waters in streams. Numbers of dead unionacean mussels observed at twelve stations on two such streams are tabulated. Relevance of drought to past and future of the mussel fauna of the streams is discussed. In a previous paper (Metcalf, 1980) kinds of unionacean mussels found at a number of stations on Big Caney River and Grouse Creek, in southcentral Kansas, were reported. These are streams originating in the Flint Hills region. Grouse Creek heads in the area of conjunction of Cowley, Butler and Elk counties and flows diagonally southwestward across Cowley County, emptying into the Arkansas River near the Kansas-Oklahoma border. Big Caney River heads in southwestern Elk County and flows across western Chautauqua County. The segment surveyed on Big Caney extended only to the southern border of Kansas. Station numbers mentioned herein are as in Metcalf (1980), with numbering beginning upstream and continuing downstream. Stations are located at 4-8 km intervals (C = Big Caney River and G = Grouse Creek). The previous survey was carried out from 1969-1979, years when intermittency of streams did not occur at stations sampled. In 1980 drought conditions in the watersheds of these streams resulted in intermittency or minimal flow at all stations. Below are climatological data (NOAA, 1970-1980; data for July-December 1980, for Grenola, from F. M. Metcalf) for four towns located on or near the watersheds of the streams noted. Grenola is located on upper Big Caney River and Elgin on its lowermost reaches in Kansas. Dexter is located near mid-length of Grouse Creek and Arkansas City 12 km WNW of its mouth. Precipitation amounts are given, first, in inches (as published) and, second, in mm (calculated). Average annual precipitation for the years 19701979 is given before, range for these years within, and precipitation for 1980 after parentheses: This content downloaded from 207.46.13.11 on Wed, 10 Aug 2016 06:33:15 UTC All use subject to http://about.jstor.org/terms 90 TRANSACTIONS OF THE KANSAS ACADEMY OF SCIENCE Grenola 35.11 (25.04-48.95) 20.76; 892 (636-1243) 527 Elgin 37.74 (29.07-46.22) 24.27; 959 (738-1174) 616 Dexter 33.41 (26.16-42.87) 20.38; 849 (664-1089) 518 Arkansas City 34.57 (26.99-47.95) 25.00; 878 (686-1218) 635 Thus, for these four stations, 1980 precipitation was some 9.5 to 14.5 inches (240-365 mm) below the average for the decade 1970-1979. In addition to low precipitation, temperatures were elevated in the summer of 1980. Average temperatures for the summer months at Cedar Vale, midlength of Big Caney River, in Kansas, for 1979 (first) and 1980 (second)