A mesocosm experiment investigating the effects of substratum quality and wave exposure on the survival of fish eggs

Abstract

In a mesocosm experiment, the attachment of bream (Abramis brama) eggs to spawning substrata with and without periphytic biofilm coverage and their subsequent survival with and without low-intensity wave exposure were investigated. Egg attachment was reduced by 73% on spawning substrata with a natural periphytic biofilm, compared to clean substrata. Overall, this initial difference in egg numbers persisted until hatching. The difference in egg numbers was even increased in the wave treatment, while it was reduced in the no-wave control treatment. Exposure to a low-intensity wave regime affected egg development between the two biofilm treatments differently. Waves enhanced egg survival on substrata without a biofilm but reduced the survival of eggs on substrata with biofilm coverage. In the treatment combining biofilm-covered substrata and waves, no attached eggs survived until hatching. In all treatments, more than 75% of the eggs became detached from the spawning substrata during the egg incubation period, and \1% of these detached eggs survived within the substratum interstices. Hence, detached eggs contributed little to the reproductive success we observed. The implications of these results on the spawning success of fish species that use freshly inundated spawning substrata in shallow waters are discussed.

Small and impoverished regional species pools constrain colonisation of restored river reaches by fishes

“…To ensure sustainable effects, the full life cycle of fishes needs to be considered. Particularly, early life stages of fishes often have special habitat requirements, with reproductive success commonly governed by the availability of suitable nursery habitats, characterised by appropriate habitat structures, as well as an appropriate water temperature and hydrodynamic regime (Kucera-Hirzinger et al, 2009;Probst et al, 2009;Stoll et al, 2010). However, where the species pools are depleted at the catchment scale, stocking (also referred to as assisted migration, assisted colonisation and managed relocation) from the nearest source population may represent a viable tool to support the establishment of reference taxa (Layzer & Scott, 2006;Vitt, Havens & Hoegh-Guldberg, 2009), especially when these reference taxa are rare or specialists.…”

Reproductive periodicity of the sparid, Acanthopagrus pacificus, on a hierarchy of temporal scales

“…The reproductive cycle of A. pacificus from tropical north‐eastern Australia shows strong temporal patterns on at least four scales; annual, within‐spawning season, within‐lunar cycle and within‐day. These comprise changes in the gonad size, the proportion of ripe gonads and gonad histology, and appear to reflect underlying patterns of alteration in the allocation of resources to direct maximum reproductive output to times when conditions are optimal for such things as gamete survival (Molony & Sheaves, 2001), survival of fertilized eggs (Stoll et al ., 2010), dispersal of fertilized eggs from the estuary (Shanks, 2009; Morgan & Fisher, 2010), or reducing predation of newly spawned eggs.…”

People, pollution and pathogens – Global change impacts in mountain freshwater ecosystems

“…Such weak disperser species, even where suitable climate space (=habitat within the climat ic preferences of the species) increases, may lose current habitat due to their incapacity to disperse sufficiently fast into newly available and suitable sites. Hence, in those species reproduction is heavily impaired when climate change impacts on the temporally matched availability of suitable reproduction habitat conditions (Probst et al, 2009;Stoll et al, 2010) and/or the availability of certain food types during critical periods of offspring development (Stenseth and Mysterud, 2002). Espe cially in highly dynamic, small water bodies (b0.5 ha in size) we know yet little about the food web dynamics between microbes, plankton and higher animals, such as amphibians.…”