Effects of habitat isolation on the recovery of fish assemblages in experimentally defaunated stream pools in Arkansas

Abstract

We removed fish from pools in two Arkansas streams to determine recolonization rates and the effects of isolation (i.e., riffle length, riffle depth, distance to large source pools, and location), pool area, and assemblage size on recovery. To determine pool-specific recovery rates, we repeatedly snorkeled 12 pools over a 40-day recovery period. Results indicated the effects of isolation on percent numerical recovery, but no effects of pool area or assemblage size. Numerical recovery of assemblages in pools separated from neighboring pools by short riffles occurred by day 30 whereas more isolated pools had not reached 70% numerical recovery by day 40. Recovery also was more rapid in downstream pools and in pools that were closer to large source pools. Finally, recovery patterns differed among species and size-classes, with large fish (<100 mm total length) recolonizing pools more rapidly than small fish. This is the first study to quantify species- and assemblage-level recolonization rates at the scale of individual pools and the effects of isolation on recovery. The findings of this study have potentially important implications for research aimed at understanding the ecology of stream fishes and predicting the consequences of land-use activities.

Effects of riffle length on the short-term movement of fishes among stream pools

“…We have shown previously that population estimates generated from snorkeling surveys in these streams are nearly identical to those generated from more invasive and laborintensive electrofishing surveys (Lonzarich et al 1998). High water clarity provided excellent conditions for identifying marked fish from distances up to 3 m.…”

“…General characteristics of the streams included bedrock and gravel substrates and dense riparian vegetation. The proportion and average size of pool and riffle habitats in the two streams were similar (Clingenpeel 1994) as were the composition, rank dominance, and densities of fish species (Lonzarich et al 1998). Physical and biological conditions during the two years of the study also were very similar.…”

“…semblage dynamics. Recent experiments have added weight to these earlier observations by showing that long riffles slow fish recolonization to defaunated pools (Lonzarich et al 1998) and reduce fish movement between pools in experimental streams (Schaefer 1999).…”

Movement and Recolonization of Potomac Sculpin in a Virginia Stream

“…Less than 20% of the slimy sculpin migrated, and 80% of those moved less than 25 m. Natsumeda (1999) found that the mean movements of the male and female Japanese fluvial sculpin Cottus pollux was less than 20 m. Petty and Grossman (2004) found that most individual mottled sculpin moved less than 3 m. The longest movement of slimy sculpin and a second, undescribed sculpin species documented by Schmetterling and Adams (2004) was 209 m. Greater distances may have been observed if traps had not obstructed movement. Some stream fishes can be highly mobile, and recolonization by some fish assemblages can occur on the scale of days or weeks (Peterson and Bayley 1993;Lonzarich et al 1998, …”

Patrones de desplazamiento de peces nativos en el Río San Pedro (cuenca del Río Valdivia, Chile)

“…Estos últimos son menos extensivos y no sincrónicos (Albanesse et al 2004), pero son igualmente de gran signifi cado ecológico. Tales movimientos locales permiten colonizar nuevos hábitats (Taylor 1997;Lonzarich et al 1998), o moverse entre microhábitats, generando una alta dinámica espacial y temporal de las poblaciones en un sistema fl uvial (Schlosser & Angermeier 1995). Estos movimientos pueden estar gatillados por factores endógenos (e.g.…”