Search results for "Spawning"
showing 10 items of 27 documents
The multi-state CASPT2 method
1998
Abstract An extension of the multiconfigurational second-order perturbation approach CASPT2 is suggested, where several electronic states are coupled at second order via an effective-Hamiltonian approach. The method has been implemented into the MOLCAS-4 program system, where it will replace the single-state CASPT2 program. The accuracy of the method is illustrated through calculations of the ionic-neutral avoided crossing in the potential curves for LiF and of the valence-Rydberg mixing in the V-state of the ethylene molecule.
Environmental Conditions along Tuna Larval Dispersion: Insights on the Spawning Habitat and Impact on Their Development Stages
2022
Estimated larval backward trajectories of three Tuna species, namely, Atlantic Bluefin Tuna (Thunnus thynnus, Linnaeus, 1758), Bullet Tuna (Auxis Rochei, Risso, 1801) and Albacore Tuna (Thunnus alalunga, Bonnaterre, 1788) in the central Mediterranean Sea, were used to characterize their spawning habitats, and to assess the impact of changes due to the major environmental parameters (i.e., sea surface temperature and chlorophyll-a concentration) on larval development during their advection by surface currents. We assumed that the environmental variability experienced by larvae along their paths may have influenced their development, also affecting their survival. Our results showed that the …
Disentangling conditional effects of multiple regime shifts on Atlantic cod productivity
2020
AbstractRegime shifts are increasingly prevalent in the ecological literature. However, definitions vary, and many detection methods are subjective. Here, we employ an operationally objective means of identifying regime shifts, using a Bayesian online change-point detection algorithm able to simultaneously identify shifts in the mean and(or) variance of time series data. We detected multiple regime shifts in long-term (59-154 years) patterns of coastal Norwegian Atlantic cod (>70% decline) and putative drivers of cod productivity: North Atlantic Oscillation (NAO); sea-surface temperature; zooplankton abundance; fishing mortality (F). The consequences of an environmental or climate-relate…
Salt tolerance of Rana temporaria: spawning site selection and survival during embryonic development (Amphibia, Anura)
1999
AbstractSpawning site selection of Rana temporaria is dependent on the salinity of the water. In the nature reserve 'Salzwiesen von Münzenberg' (Germany) the frogs avoided increased conductivity values, Cl- ion concentrations and salinities and selected lower values for spawning. In the laboratory Gosner stages 20/21 to 22/23 were more sensitive to sodium than the earlier G stages 8 to 20/21 (exposition for 72 h) though they were exposed for the shorter time period of 24 h. The 'no observed effect concentration' (NOEC) between G stages 8/9 and 20/21 was 648 ppm (3350 μS, 2.2‰ salinity) for Na+ and 1872 ppm (6500 μS, 4.0‰ salinity) for K+. The NOEC between G stages 20/21 and 22/23 was 1490 p…
Natural recruitment contributes to high densities of grass carp Ctenopharyngodon idella (Valenciennes, 1844) in Western Europe
2015
Introductions of grass carp, well known for their potentially negative ecosystem effects, have been performed in several countries around the world. As the species was considered unable to reproduce naturally under non-native environmental conditions, little attention was initially given to its invasive potential. We studied an area in northern-Italy where, contrary to expectations, introductions that were performed in the early 80s still exert a considerable pressure on aquatic macrophytes. In order to reveal whether the observed population dynamics are the result of natural events or stocking we analysed the density, age- and size-structure of the grass carp population and the migration p…
Communal pair spawning behaviour of vendace (Coregonus albula) in the dark
2018
Mating in nature is rarely random, and most fish species have refined mating systems. The vendace (Coregonus albula) is a short‐lived, small‐sized, cold‐water‐adapted pelagic schooling species that is known to spawn in groups, but the actual mating system of this species, like many other group‐spawning fishes, has not been described in detail. Vendace typically spawn in the littoral or sublittoral zones of lakes in late autumn, and the hatching of larvae occurs close to icebreak in the following spring. In our large study lake, vendace larvae were caught in 93% of 1,149 random sampling locations lake‐wide. We examined the courtship and mating of vendace under experimental conditions by noni…
Multiple-batch spawning: a risk-spreading strategy disarmed by highly intensive size-selective fishing rate
2022
Can the advantage of risk-managing life-history strategies become a disadvantage under human-induced evolution? Organisms have adapted to the variability and uncertainty of environmental conditions with a vast diversity of life-history strategies. One such evolved strategy is multiple-batch spawning, a spawning strategy common to long-lived fishes that ‘hedge their bets' by distributing the risk to their offspring on a temporal and spatial scale. The fitness benefits of this spawning strategy increase with female body size, the very trait that size-selective fishing targets. By applying an empirically and theoretically motivated eco-evolutionary mechanistic model that was parameterized for …
Indications of polymorphism in the behaviour and morphology of burbot (Lota lota) in a European lake
2022
AbstractIn this study, polymorphism in behaviour, morphology, and stable isotope signatures of burbot from Lake Southern Konnevesi, Finland, Europe, was examined. First, local knowledge was collected on exceptional polymorphism of the spawning behaviour and morphology of burbot. These phenomena were then studied based on catch samples. Interviews and catch sample analyses suggested two morphs of burbot: one morph spawning in late February in the littoral zone and other in late March, in deep profundal, depths of about 30 m. Fish caught from the profundal zone had higher average proportional somatic body weights and wider heads than those caught from the littoral spawning sites in February. …
Data from: Local cod (Gadus morhua) revealed by egg surveys and population genetic analysis after longstanding depletion on the Swedish Skagerrak coa…
2019
Dramatic and persistent reductions in Atlantic cod (Gadus morhua) are common in many coastal areas. While offshore cod stocks still were abundant and productive, the Swedish west coast showed signs of diminishing adult cod abundance at the beginning of the 1980s, where the local cod component was considered to be extirpated. To survey the present cod spawning activity and stock composition, we initiated egg trawling over two consecutive years (203 hauls in total) in combination with population genetic analyses (425 individually genotyped eggs). Here, we provide evidence of cod spawning at the Swedish Skagerrak coast, suggesting recolonization or that local cod has recovered from a nearly de…
Data from: Seasonal dynamics of Atlantic herring (Clupea harengus L.) populations spawning in the vicinity of marginal habitats
2015
Gillnet sampling and analyses of otolith shape, vertebral count and growth indicated the presence of three putative Atlantic herring (Clupea harengus L.) populations mixing together over the spawning season February–June inside and outside an inland brackish water lake (Landvikvannet) in southern Norway. Peak spawning of oceanic Norwegian spring spawners and coastal Skagerrak spring spawners occurred in March–April with small proportions of spawners entering the lake. In comparison, spawning of Landvik herring peaked in May–June with high proportions found inside the lake, which could be explained by local adaptations to the environmental conditions and seasonal changes of this marginal hab…