Abstract A recent meta‐analysis indicates that trophic cascades (indirect effects of predators on plants via herbivores) are weak in marine plankton striking contrast to freshwater ( Shurin et al. 2002 , Ecol. Lett. 5, 785–791). Here we show a community consisting jellyfish, calanoid copepods and algae, jellyfish predation consistently reduced but produced two distinct, opposite responses algal biomass. Calanoid act as switch between alternative along food chains different length with...

The way in which density‐dependent effects are partitioned amongst survival, growth and dispersal key determining the temporal spatial dynamics of populations. Here we propose a mechanistic approach to understanding how relative importance these sources density dependence can change over ontogeny through changes abilities, energy stores mortality risks. Whereas potential for active typically increases as function body size, susceptibility starvation predation decreases. joint effect...

Abstract Atlantic salmon populations have declined in recent decades. Many of the threats to species during its freshwater and coastal residency periods are known, management approaches available mitigate them. The global scale climate change altered ocean ecosystems make these more difficult address. Managers need be aware that promoting strong, healthy, resilient wild migrating from rivers is optimal approach currently reduce impacts changing low marine survival. We argue a fundamental...

Nonanadromous Atlantic salmon (Salmo salar) exhibit a combination of variation in life history, habitat, and species co-existence matched by few vertebrates. Distributed eastern North America northern Europe, habitat ranges from hundreds metres river to Europe’s largest lakes. As juveniles, those with access lake usually migrate feed grow prior reproduction. Prey such as smelt (Osmerus mordax, Osmerus eperlanus) vendace (Coregonus albula) facilitate large body size (50–85 cm at maturity)...

Abstract Domestication involves adapting animals to the human-controlled environment. Genetic changes occurring during domestication process may manifest themselves in phenotypes that render domesticated maladaptive for life wild. Domesticated Atlantic salmon frequently interbreed with wild conspecifics, and their offspring display reduced survival However, mechanism(s) contributing lower remains a subject of conjecture. Here, we document higher susceptibility predation by brown trout...

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout JournalEditorsTheme Sections 270:199-207 (2004) - doi:10.3354/meps270199 Moderate increase in biomass of omnivorous copepods may ease grazing control planktonic algae Olav Vadstein1,*, Herwig Stibor2, Bettina Lippert2, Kjetil Løseth3, Wendy Roederer2, Line Sundt-Hansen3, Yngvar Olsen3 1Department Biotechnology, and 3Department Biology,...

Abstract The EU Water Framework Directive (WFD) aims to achieve good status of aquatic habitats. Classification ecological and identifying the stressors impacting habitats is essential for achieving this aim. Here, we evaluate different methods indices assessing in a hydropower-regulated river central Norway using kick-sampling macroinvertebrate identification through morphology DNA as well environmental DNA. In Norway, ASPT index (Average Score Per Taxon) commonly used condition general,...

We predict an increase in parr recruitment and smolt production of Atlantic salmon (Salmo salar) populations along a climate gradient from the subarctic to Arctic western northern Norway response future change. Firstly, we predicted local stream temperature discharge downscaled data obtained Global Climate Models. Then, developed spatially explicit individual-based model (IBM) parameterized for freshwater stage, with combinations three different postsmolt survival probabilities reflecting...

Rapid growth and development are associated with several fitness-related benefits. Yet, organisms usually grow more slowly than their physiological maximum, suggesting that rapid may carry costs. Here we use coho salmon ( Oncorhynchus kisutch ) eggs of wild transgenic genotypes to test whether causes reduced tolerance low levels oxygen (hypoxia). Eggs were exposed four different durations hypoxia, survival recorded until the end larval stage. Survival rates decreased increasing duration but...

Abstract Studies of hydropeaking‐induced stranding mortality on fish populations have been confined to analysis empirical data and/or short‐term hydraulic‐habitat modelling individual events and are thus limited as how they may be used infer long‐term effects in populations. In this study, the an Atlantic salmon population were simulated using individual‐based model with objective determining sensitivity dynamics stranding. It was found that density‐dependent (an alternative source juvenile...

1 Rapid growth is often associated with several fitness-related benefits. However, in most organisms rates are rarely maximized, suggesting that trade-offs limit the benefits of rapid growth. To enable sustained high growth, behavioural modifications incurring costs may be required, and these responsible for evolution sub-maximal rates. 2 In a field experiment it was tested whether brown trout achieved by increasing potentially costly movement activity. Causal relations were obtained...

Hydropower plant operating conditions are expected to change be more in tandem with intermittent power production so as meet the requirements of Paris Agreement, which turn may negatively impact ecological downstream hydropower plants. The current study investigates how highly flexible several salmonid species (European grayling, Atlantic salmon and brown trout) River Umeälven, a major river northern Sweden; specifically, changes hydropeaking frequency affect area watercourse that is...

The study examined the density‐mediated effects on growth, survival and dispersal of wild farmed Atlantic salmon Salmo salar offspring in period immediately following emergence, using a substitutive design. In small confined stream channels, parr coexisting with had significantly poorer survival, than alone. Density did not affect this relationship. larger unconfined entered downstream trap higher numbers allopatry. results suggests that during earliest life stages, S. can outcompete ,...

Abstract Escaped farmed Atlantic salmon interbreed with wild salmon, leaving offspring that often have lower success in nature than pure salmon. On top of this, presence descendants can impair production wild‐type recruits. We hypothesize both these effects connect having acquired higher standard metabolic rates (SMR, the energetic cost self‐maintenance) during domestication. Fitness‐related advantages phenotypic traits associated high SMR and (e.g., social dominance) depend on environmental...

Abstract Hydropeaking (the release of water pulses at hydropower plants) results in temporary reductions river channel water‐covered area downstream, which may cause fish mortality through stranding. We used a mechanistic modelling approach to examine how both the form hydropeaking cycle and characteristics affected control stranding fish. modelled response Atlantic parr regulated watercourse central Norway River Nidelva) using an individual‐based population model designed explicitly...

A study was undertaken to examine the responses of three Atlantic salmon Salmo salar strains growth hormone (GH) treatment. positive response sustained‐release GH implants found in two wild (Namsen and Imsa) as well one domesticated strain (AquaGen). The data revealed that growth‐selected AquaGen has further potential, however, a stronger observed which outgrew after These observations suggest some potential may have been lost during selection for rapid strain. In September, parr were...

Summary 1. Although life‐history theory predicts that juvenile growth rates should be high, there is substantial evidence most juveniles grow below their physiological maximum. The endocrine system plays an important role in the determination of fundamental traits, and hormones often serve as a link between organism’s environment expression trait. Particularly, trait, which strongly associated with hormone (GH) fish, well vertebrates. 2. To elucidate trade‐offs related to elevated GH fish...

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout JournalEditorsSpecials 45:207-218 (2006) - doi:10.3354/ame045207 Trophic cascades mediated by copepods, not nutrient supply rate, determine development of picocyanobacteria Line E. Sundt-Hansen1,5, Yngvar Olsen1, Herwig Stibor2, Mikal Heldal3, Olav Vadstein4,* 1Norwegian University Science and Technology, Department Biology, Trondhjem...

The effects of growth hormone (GH) implants on aggression, and ability to win dyadic territorial conflicts were studied in brown trout Salmo trutta parr. Bovine GH or vehicle (C) was given either the territory owner intruder four treatment combinations: C C, GH, (owner intruder). GH‐treated intruders initiated significantly more compared control intruders. Furthermore, tended increase aggression intruder. This indicates that have scope for motivational increase, while motivation owners is...

Abstract “Småblank” is the only population of Atlantic salmon in Europe living its entire life river habitat without performing migrations to sea or lakes. Home range size and use were compared between an unregulated tributary hydro-power regulated parts main during 2014–2017. In total, 140 småblank tagged with radio transmitters tracked for 4–5 months. Tagged fish tended stay within small areas: average 50% home was 1123 m 2 95% 4416 . Mean distance furthermost positions individual tracking...