Causes of larval drift of the fire salamander, Salamandra salamandra terrestris, and its effects on population dynamics

Abstract

The larval drift of the fire salamander was investigated over a period of three years in a mountain brook (Niederbergisches Land, F.R. Germany), as well in a laboratory water channel. The rate of larval drift fluctuated between 19% and 41% of the total population of larvae in a defined section of the brook during these three years. Most (83%) of the drifting larvae were hatchlings or very young stages. The drift was dependent on the strength of the current, the number of spawning females, the presence of suitable hiding places, sufficient space and adequate food. Hungry larvae drifted more often than satiated animals. The drift behaviour of hatchlings differed distinctly from that of older larvae. The significance of ecological factors on larval drift is discussed. It is evidently a more important factor in selection than has hitherto been recognized.

Hydraulic microdistribution patterns of larval fire salamanders (Salamandra salamandra salamandra) in the Weidlingbach near Vienna, Austria

“…Although their morphology is closer to pond‐dwelling forms ( Griffiths 1996), fire salamander larvae predate as stream‐dwellers do, being less selective than lentic larvae ( Himstedt 1967). Fire salamander larvae lack morphological adaptations to resist drift, such as suckers or a flattened body known from lotic tadpoles; as a consequence, about 30% of larval salamander populations are regularly subject to downstream drift ( Thiesmeier & Schuhmacher 1990; Thiesmeier 1992). One severe flood was observed in May 1996, during the spawning season, which severely reduced larval density, especially at sampling sites near the source.…”

“…One severe flood was observed in May 1996, during the spawning season, which severely reduced larval density, especially at sampling sites near the source. As smaller larvae are less resistant to drift than older ones ( Thiesmeier & Schuhmacher 1990), the impact of spates during the larval hatching period is rather severe. As a result of the poor infiltration capacity of the soil, the headwaters of brooks in the Wienerwald are frequently flooded, causing a complete reorganization of the stream bed and a redistribution of lentic and lotic habitats.…”

“…Few data are available on the effects of hydraulic parameters on distribution patterns of fire salamander larvae (e.g. Thiesmeier & Schuhmacher 1990; Thiesmeier 1994a; Thiesmeier & Sommerhäuser 1995). The purpose of the present study was therefore to obtain quantitative information on the hydraulic microdistribution of this species in a deciduous woodland stream typical for its Central European breeding habitats.…”

Coexistence in streams: do source–sink dynamics allow salamanders to persist with fish predators?

“…Salamanders, however, also occupy headwater stream reaches that fish are unable to access because of movement barriers such as waterfalls (Storfer and Sih 1998;Barr and Babbitt 2007). Salamander dispersal from these upper, fishless reaches to lower reaches with fish has been suggested as a mechanism for coexistence with fish (Petranka 1983;Thiesmeier and Schuhmacher 1990;Resetarits 1995), but this mechanism has not been tested.…”

Short Notes

“…It is interesting to note this though the experimental conditions inhibited mortality due to predation and larval drift, which can also be an important mortality factor (Petranka and Sih, 1986) especially if larvae are drifted to fish-dominated downstream areas (Thiesmeier and Schuhmacher, 1990;Thiesmeier 1994). Thus the mortality measured on this experimental population should arise form other sources, which might include consumption by Gammarus species after injuries (observed) or cannibalism.…”