Timing matters: species‐specific interactions between spawning time, substrate quality, and recruitment success in three salmonid species

Abstract

Substratum quality and oxygen supply to the interstitial zone are crucial for the reproductive success of salmonid fishes. At present, degradation of spawning grounds due to fine sediment deposition and colmation are recognized as main factors for reproductive failure. In addition, changes in water temperatures due to climate change, damming, and cooling water inlets are predicted to reduce hatching success. We tested the hypothesis that the biological effects of habitat degradation depend strongly on the species-specific spawning seasons and life-history strategies (e.g., fall- vs. spring-spawners, migratory vs. resident species) and assessed temperature as an important species-specific factor for hatching success within river substratum. We studied the species-specific differences in their responses to such disturbances using egg-to-fry survival of Danube Salmon (Hucho hucho), resident brown trout (Salmo trutta fario), and migratory brown trout (Salmo trutta lacustris) as biological endpoint. The egg incubation and hatching success of the salmonids and their dependence on temperature and stream substratum quality were compared. Hatching rates of Danube salmon were lower than of brown trout, probably due to higher oxygen demands and increased interstitial respiration in spring. Increases in maximum water temperature reduced hatching rates of resident and migratory brown trout (both fall-spawners) but were positively correlated with hatching rates of Danube salmon (a spring-spawner). Significantly longer incubation periods of resident and migratory brown trout coincided with relatively low stream substratum quality at the end of the egg incubation. Danube salmon seem to avoid low oxygen concentrations in the hyporheic zone by faster egg development favored by higher water temperatures. Consequently, the prediction of effects of temperature changes and altered stream substratum properties on gravel-spawning fishes and biological communities should consider the observed species-specific variances in life-history strategies to increase conservation success.

The importance of stream interstitial conditions for the early‐life‐stage development of the European nase (Chondrostoma nasus L.)

“…Our results confirm that higher rates of fine sediment accumulation also had a negative effect on hatching rates of the nase as a cyprinid species, both in the incubation systems and the reference incubation boxes on site, even though the incubation period for nase eggs is substantially shorter compared to salmonids. This might also be of evolutionary relevance, as found for the Danube salmon (Hucho hucho L.) and the brown trout (Salmo trutta L.) (Sternecker, Denic, & Geist, 2014;Sternecker & Geist, 2010). Threshold effects observed in other studies for salmonids revealed that survival rates dropped rapidly when the percentage of the most influential fine sediment class (<0.85 mm) was greater than 10% (Jensen, Steel, Fullerton, & Pess, 2009), resulting in oxygen deficits within the interstitial zone that can also impair nase development (Keckeis et al, 1996).…”

“…To date, research on the effects of fine sediments on fish has been concentrated on species of relatively few families, notably salmonids (Kemp, Sear, Collins, Naden, & Jones, 2011;Sternecker et al, 2013). This might also be of evolutionary relevance, as found for the Danube salmon (Hucho hucho L.) and the brown trout (Salmo trutta L.) (Sternecker, Denic, & Geist, 2014;Sternecker & Geist, 2010). This might also be of evolutionary relevance, as found for the Danube salmon (Hucho hucho L.) and the brown trout (Salmo trutta L.) (Sternecker, Denic, & Geist, 2014;Sternecker & Geist, 2010).…”

Extent and Causes of Siltation in a Headwater Stream Bed: Catchment Soil Erosion is Less Important than Internal Stream Processes

“…It is thus not surprising that several publications reported on low or degrading biological functionality of this river (e.g. Sternecker et al ., ; Pulg et al ., ; Sternecker et al ., ).…”

Genetic and morphological divergence along the littoral-pelagic axis in two common and sympatric fishes: perch,Perca fluviatilis(Percidae) and roach,Rutilus rutilus(Cyprinidae)

“…(), olfactory cues may contribute to mate choice, shoaling behaviour, and kinship. Examples of segregated spawning contributing to genetic divergence have been observed in several other fishes – salmonids (Vähä et al ., ; Sternecker, Denic & Geist, ), whitefish (Bernatchez et al ., ), smallmouth bass (Stepien, Murphy & Strange, ), and herring (McPherson, Stephenson & Taggart, ) – and thus is worthy of further investigation in perch and roach.…”