THE CRAYFISHES
(Crustacea, Cambaridae)
David W. Barr
Fig. 1 Major drainage basins intersecting the Mixedwood Plains Ecozone.
Fig. 2 Position of the study area in eastern North America, showing the major Wisconsinan glacial refugia (A, M, R) and the major routes of re-invasion for aquatic organisms (1-5): A - Atlantic refugium, M - Mississippian refugium, R - Missourian refugium; 1 - Lower Michigan Peninsula route, 2 - Fort Wayne route, 3 - Mohawk route, 4 - Champlain route, 5 - Champlain/St. Lawrence route (after Mandrak and Crossman 1992).
Fig. 3 Uniform range maps for six of the eight crayfish species known to occur in the study area.
Fig. 4 Discontinuous range maps for two of the eight crayfish species known to occur in the study area and a species density map resulting from combining the two.
Fig. 5 The species density or biodiversity map representing the four cambariform crayfish species occurring in the Mixedwood Plains Ecozone.
Fig. 6 The species density or biodiversity map representing the four Orconectes species occurring in the Mixedwood Plains Ecozone.
Fig. 7 Map representing major land-use categories in the western and central portions of the study area.
Fig. 8 Map derived from Figs. 8 and 4b, representing the relative vulnerability of the crayfish Fallicambarus fodiens to local extirpation.
Fig. 9 Progressive increase in the range of the invading species, Orconectes rusticus , in the study area over a period of 30 years. Fig. 9d shows the time series delineated in 9a-c superimposed to demonstrate a pattern of centrifugal range expansion.