The ‘egg sandwich’: a method for linking spatially resolved salmonid hatching rates with habitat variables in stream ecosystems

Ecology of Freshwater Fish

2010

Self Cite

Sternecker K, Geist J. The effects of stream substratum composition on the emergence of salmonid fry.  Ecology of Freshwater Fish 2010: 19: 537–544. © 2010 John Wiley & Sons A/S Abstract – Salmonid fishes are target species for the conservation of freshwater habitats, but their natural reproduction is often insufficient. The emergence of fry is a crucial phase in the life cycle of salmonids and the stream substratum is the key habitat which regulates the emergence success. In this study, brown trout (Salmo trutta) and Danube salmon (Hucho hucho) eggs were exposed to different sediment textures and the emergence and the postemergence survival and growth were observed under constant water chemical conditions in the laboratory. In both species, textural effects on emergence rate, chronology of emergence, survival rate after emergence and growth after emergence were detected. Fine‐textured substratum (5–8 mm) formed a physical barrier to the posthatch migration of salmonids from the interstitial zone to the open water. The time period between the first and the last emerged fish was shorter in treatments with fine texture compared with coarse substratum. The survival rate was higher in treatments of coarser sediment. The effects of different textures on the growth of fry after emergence differed between brown trout and Danube salmon, which can be explained by different life history strategies. These results suggest that physical characteristics of substratum texture can have strong effects on salmonid emergence, and ultimately on the persistence of salmonid populations. They also suggest that biodiversity conservation in stream ecosystems can greatly benefit from an inclusion of the physical characteristics of the stream bed into catchment‐based management plans.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The effects of stream substratum composition on the emergence of salmonid fry

Sternecker

Ecology of Freshwater Fish

2010

Self Cite

“…A total of 77 egg sandwich boxes (ES; Pander et al 2009) were exposed during three consecutive years and spawning seasons (2009–2011). Of these ES, 37 were filled with Danube salmon eggs (16 × River Lech, 21 × River Moosach), 29 with eggs of resident brown trout (10 × River Lech, 19 × River Moosach), and 12 with eggs of migratory brown trout (River Obernach).…”

Section: Methodsmentioning

confidence: 99%

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

Sternecker

Denic

2014

Ecology and Evolution

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.

“…Thus, control hatching rate complied with the requirements of at least 66% of the Fish, Early-Life Stage Toxicity Test [30]. There were no differences between treatments (one-way ANOVA: F (1,18) = 0.727, p = 0.691).…”

Section: Salmonid Egg Developmentmentioning

confidence: 56%

“…Consequently, salmonid egg exposure Acc e p ted P r e p r i nt This article is protected by copyright. All rights reserved systems have already been established for bioindication in streams [30,31], but these systems are not ideal for ecotoxicological testing in the laboratory.…”

Section: Acc E P Ted P R E P R I Ntmentioning

confidence: 99%

Miniature circulatory systems: A new exposure system for ecotoxicological effect assessments in riverine organisms

Feiner

Beggel

Enviro Toxic and Chemistry

2016

Long-term effect assessments in ecotoxicological investigations are important, yet there is a lack of suitable exposure systems for these experiments that can be used for riverine species. A cost-efficient miniature circulatory system was developed that was evaluated for its applicability in long-term exposures in 2 stream-dwelling species: brown trout (Salmo trutta) and an amphipod (Gammarus roeseli). In an egg-to-fry exposure of S. trutta, the toxicity of 2 reverse osmosis concentrates was investigated as examples. Control hatching rate of yolk sac fry was 75 ± 7% and thus complies with the Organisation for Economic Co-operation and Development validity criterion (≥66%). The reverse osmosis concentrates did not impair the hatching rate in any tested concentration. In G. roeseli, mortality rates remained below 20% during a 21-d cultivation, fulfilling the common validity criterion in ecotoxicological testing. Mortality was significantly lower when the species was fed with conditioned alder leaves instead of an artificial shrimp food. Finally, a toxicity test on G. roeseli using copper as the test substance revealed median lethal concentration (LC50) values of 156 μg/L after 96 h and 99 μg/L after 264 h, which is in line with literature findings using other accepted exposure units. In conclusion, the miniature circulatory system provides a novel and cost-efficient exposure system for long-term investigations on riverine species that may also be applicable for other species of fishes and macroinvertebrates. Environ Toxicol Chem 2016;35:2827-2833. © 2016 SETAC.