Impact of drought upon fish assemblage structure in two South Carolina Piedmont streams

Abstract

The effects of drought on fish assemblages were studied in the Indian Creek (228 km 2 ) and Kings Creek (46 km 2 ) watersheds located in the Piedmont Province of South Carolina. Water and fish samples were collected at 13 localities during drought conditions in 2000 and again under post-drought conditions in 2003. Abundance, species richness, and Simpson's diversity were calculated for each locality, and the masses and lengths of individual fishes were measured to determine total biomass and length distributions for each species. Assemblages were significantly different from 2000 to 2003 at 10 of the 13 sample localities (v 2 test for association; p < 0.05). The family Cyprinidae (minnows) was numerically dominant in both years and in both watersheds, but their dominance declined somewhat following the drought due to lower numbers of Nocomis leptocephalus and Notropis lutipinnis in 2003 collections. However, some cyprinids increased in abundance in 2003 collections, most notably Semotilus atromaculatus and Hybopsis hypsinotus. Abundance of catostomids (suckers) and ictalurids (catfish) was also decreased post drought. Conversely, centrarchids (sunfish) increased in dominance in 2003, especially the species Lepomis macrochirus and Lepomis gulosus. Many more juveniles and young of the year were observed in 2003 collections, suggesting that most species exhibited greater reproductive success following the drought. The significant differences in water chemistry observed between the two years were not associated with any change in fish community structure. Instead, we attributed the observed differences in fish assemblages to changes in habitat structure associated with higher rainfall during post-drought conditions. Finally, sample localities showed high variability in common measures of assemblage structure, including abundance, species richness, and diversity. We hypothesize that the observed variability in community structure is caused by the heterogeneous habitat structure and morphology of these small Piedmont Province streams.

Water diversion reduces abundance and survival of two Mediterranean cyprinids

“…The absence of observed mortality due to tagging and the negligible percentage of tag loss suggested no substantial violation of two fundamental assumptions of mark-recapture studies, that is equal survival probability for marked and unmarked individuals and no tag loss during the study period (Krebs, 1989). Barbel survival and abundance were lowest in the intermittent stratum 2 and highest in the more stable environmental conditions present in the control segments (stratum 1 and S10) and the recovery reach (stratum 3), a pattern reported for other fish assemblages (Grossman, Ratajczak, Cawford, & Freeman, 1998;Keaton, Haney, & Andersen, 2005;Magalhães, Beja, Canas, & Collares-Pereira, 2002;Magalhães et al, 2007;Matthews, 1998).…”

Responses of fish and invertebrates to floods and droughts in Europe

“…There is evidence that droughts eliminate weak individuals and prevent invasive species, and so can have a positive impact on the ecosystem (Everard, ). Both droughts and floods may also be favorable for fish reproduction and recruitment (Keaton, Haney, & Andersen, ; Cattaneo, Carrel, Lamouroux, & Breil, ), and floodplain inundation may also lead to short‐ and long‐term increases in ecological metrics of invertebrate assemblages (Ballinger, Nally, & Lake, ). Furthermore, even when the effects are “harmful”, that is, biota and ecological processes have been greatly diminished after the disturbance, they often have sufficient capacity to recover (Lake, ).…”

Inter-seasonal persistence and size-structuring of two minnow species within headwater streams in the Eastern Cape, South Africa

“…The genus is, nevertheless, known to persist within unstable and changing environmental conditions owing to a combination of flexible life history patterns, physiological tolerances and both morphological and dietary plasticity (Skelton, 1988;Cambray, 1994). Maintaining stable populations within unstable environments by both species suggests adaptations that are typical of opportunist or habitat generalists species (Er} os and Grossman, 2005;Keaton et al, 2005). The patterns in densities indicate stable populations within the headwater streams for the two species.…”

“…Predation risk in headwater streams can also be size-dependent. Population stability in these streams, based on density and relative abundance may, however, vary in response to severity of environmental conditions in habitats where populations are able to persist in both benign and harsh conditions (Keaton et al, 2005). Stream fish therefore select habitats that provide refuge and permit survival in harsh environmental conditions (Koehn et al, 1994).…”