Interactive Effects of Different Temperatures and Salinities on Growth,Feed Conversion Efficiency,and Blood Physiology in Juvenile Spotted Wolffish,Anarhichas minor Olafsen

The aim of this study was to investigate the effects of different salinities and temperatures and their possible interactive effect on growth performance, feeding parameters, and blood physiology in juvenile spotted wolffish, Anarhichas minor, reared at different temperature (7 and 10 C) and salinity (15, 25, and 34‰) combinations. There was a significant interactive effect between temperature and salinity on growth, as a growth‐enhancing effect was seen at intermediate and full salinities at higher temperature, whereas the reciprocal trend was seen at lower temperature. Mean total feed consumption, daily feeding rate, and feed conversion efficiency were all highest at the intermediate salinity at 10 C, whereas at 7 C, the feeding parameters were highest at low and intermediate salinities. Blood plasma sodium content was lowest at 15‰, whereas the opposite trend was seen in partial pressure of CO₂ and bicarbonate in blood where the highest concentrations were seen at 15‰. This study demonstrates that spotted wolffish has a high osmoregulatory and acclimatory capacity. In an aquaculture context, growth of juvenile spotted wolffish can be improved by rearing the species at high temperature and intermediate salinity combinations at least in a limited period of the juvenile phase.     

Spent brewer's yeast as a replacement for fishmeal in diets for giant freshwater prawn (Macrobrachium rosenbergii), reared in either clear water or a biofloc environment

A 90‐day feeding experiment was conducted in order to test spent brewer's yeast as a replacement for fishmeal in diets for giant freshwater prawn (Macrobrachium rosenbergii) reared in either a recirculating aquaculture system (RAS) or a biofloc system. Triplicate groups, each of 20 prawn (6.7 ± 0.03 g), were randomly assigned to 24 identical tanks. Twelve tanks were connected to the RAS, and the other 12 tanks were connected to the biofloc system which were initially supplemented with Bacillus subtilis, molasses and blood meal to achieve a C:N ratio of 20:1. Four iso‐nitrogenous (350 g/kg) and iso‐energetic (19 MJ/kg) diets where 0%, 20%, 40% and 60% of fishmeal protein was replaced by spent brewer's yeast. Neither growth nor survival was affected (p > 0.05) by increasing levels of brewer's yeast. The exception, being fish given 60% replacement with brewer's yeast, reared in biofloc, which displayed a higher (p < 0.05) growth than fish given 40% replacement, reared in clear water. The feed conversion ratio of prawn reared in the biofloc environment was lower than in the clear water. We concluded that spent brewer's yeast represents a possible 60% substitute for fishmeal in giant freshwater prawn diets, especially for prawn reared in a biofloc environment.     

Inter‐individual variation in the dominant intestinal microbiota of reared Atlantic cod (Gadus morhua L.) larvae

The diversity of the microbiota in 15 Atlantic cod (Gadus morhua L.) larvae from three different hatcheries with variable food type and water treatment was characterized with culture dependent and independent approaches. The culture‐dependent approach was phenotypic characterization of bacterial isolates based on 16 tests, and the culture‐independent approach was terminal restriction fragment length polymorphism (T‐RFLP) of PCR amplified 16S rRNA. Both approaches revealed large inter‐individual differences in the microbiota of cod larvae. Data from real time PCR indicate substantially lower variation in bacterial number larva^?1 both within and between hatcheries than the data on colony forming units, resulting in an estimated four orders of magnitude variation in culturability between larvae. Considerably higher richness and diversity were observed with T‐RFLP than with phenotypic characterization, and no correlation between the two approaches was found for diversity indexes calculated at the individual level. Dissimilarity in the composition of the microbiota between individuals from the same rearing environment was comparable to the dissimilarities between hatcheries. The large inter‐individual variation is important to consider when designing experiments, as pooling of individuals will completely mask this variability. We conclude that colonization of individual cod larvae by bacteria seems to be a stochastic and not a deterministic process, which is not well understood.     

Seasonal and diel effects on the activity of northern pike studied by high‐resolution positional telemetry

Abstract – Temperate lakes can be ice covered for several months each year, yet little is known about the behaviour and activity of the fish during the cold season. As northern pike represents the top of the food web in many northern temperate lakes and may structure the ecosystem both directly and indirectly, a detailed understanding of the behaviour of this species during winter is important. We continuously monitored the activity of adult northern pike (Esox lucius) in a small temperate lake from late summer to winter for two consecutive years using an automatic acoustic positional telemetry system. Four subsample periods representing different temperature regimes from each year were chosen for further investigation. The results revealed that pike activity was similar between seasons. In all periods, a distinct diel pattern, showing increased activity during day as compared to night, was evident. Our findings indicate that the fish component of temperate lentic ecosystems can be more active during the cold season than previously assumed. This may have implications for the structuring effect of pike on the lower trophic levels.     

An integrative insight into the synsacral canal of fossil and extant Antarctic penguins

The lumbosacral-canal system in birds most likely operates as a sense organ involved in the control of balanced walking and perching, but our knowledge of it is superficial. Penguins constitute interesting objects for the study of this system due to their upright walking, but only the Humboldt penguin, Spheniscus humboldti, and some incomplete fossil penguin synsacra have been studied in this respect. Here, we give an integrative comparative insight into the synsacral canal of extant Emperor penguin, Aptenodytes forsteri, Adelie penguin, Pygoscelis adeliae, and Eocene giant Anthropornis and/or Palaeeudyptes Antarctic penguins, using computed tomography imaging and associated data-extraction methodologies, complemented by analytical approaches ranging from geometric morphometrics to modularity, curvature, and wavelet analyses. We document that the variability in the number of synsacro-lumbar vertebrae is evolutionarily conserved, and all studied synsacra possess osteological correlates of the lumbosacral-canal system. We also found that Eocene and extant Antarctic penguins were separable on the basis of the main direction of the shape-related (size-independent) variability within said system, and A. forsteri was unique in the entire studied set in terms of the relative cranial shift of this compound structure. Moreover, we suggest that the evolutionary processes, shaping both the terrestrial posture and gait, were responsible, in extant penguins, for the increased simplicity and stability of the synsacral canal cross-sectional periodic patterns, as well as pave the way for the lumbosacral-canal system modularity characterized by reduced atomization/complexity.     

Damage by rats Rattus norvegicus to breeding birds on Danish islands

Occurrence of rats Rattus norvegicus was recorded in Danish islands during the period 1970–1979. Rats apparently became common during the 1960s and 1970s. Their frequency fluctuated, indicating a possible 4-year cycle. Most rat colonisations lasted a single year. Geographical differences in their frequency may be caused by regional differences in distribution of larid colonies. Rat distribution did not follow the pattern suggested by the theory of island biogeography; presence of larids may be of major importance. When rat populations in hedges, ponds and streams are at maximum population density in autumn, pregnant females emigrate to, and so colonise, islands. Flooding and the severity of the winter may cause extinction. Food supply and predation may be of importance in limiting rat numbers. Breeding birds suffer, especially those placing their nests near rat runs; rat predation on adults may have serious consequences for a long-lived species, whereas that on eggs and young is insignificant. Some larid species renest in the immediate vicinity when predated by rats; others desert their dense colonies. Rat control is successful in small islands, whereas large island populations are only exterminated with difficulty. They should be controlled to prevent predation and to keep breeding grounds usable. This should be done in late winter when population density is low and food-supply insufficient.     

Mechanisms regulating inter‐annual variability in zooplankton advection over the Lofoten shelf,implications for cod larvae survival

Variability in the availability of suitable prey (mainly nauplii stages of Calanus spp.) in the early life stages of cod is likely a significant contributor to the fluctuations in the year‐class strength in the Arcto Norwegian cod stock. We have investigated the origin of the Lofoten shelf population of Calanus using a particle tracking model approach based on velocity fields simulated from 2002 to 2012. By performing backwards simulations of trajectories from particles released on the Lofoten shelf in early spring, we assessed the relative contribution of potential Calanus sources, such as the Lofoten Basin, the local overwintering on the continental shelf and the adjacent fjords. This analysis revealed significant interannual differences in advection patterns mainly driven by changes in wind conditions and variable strength of the Norwegian Coastal Current. Most of the particles advected into our study area originated on the shelf, and contrary to expectations, only a few originated from the Lofoten Basin where Calanus abundances tend to be high. These results suggest that contribution from the Lofoten Basin to the early spring shelf Calanus population may be overestimated and that contribution from more local sources, especially from adjacent fjords, may play a more important role than what has been previously anticipated. Our results highlight the necessity to improve quantification of shelf‐fjord exchange processes, as these may contribute more to the regulation of spring zooplankton stocks on the northern Norwegian shelf, and, as a result, may affect the survival of cod larvae in this area.     

Some visual aspects of planting design and silviculture across contemporary forest management paradigms – Perspectives for urban afforestation

There is a pan-European interest in increasing the amount of woodland cover, particularly in areas close to urban populations. However, in the enthusiasm for planting trees, is enough forethought given to visual aspects of woodland stand interiors? This paper conceptualises and assesses visual aspects of planting designs and silvicultural principles across three contemporary forest management paradigms: the commercial, the nature-based, and the urban paradigm. Planting design models and silvicultural treatments were conceptualised from a review combined with case studies. Using profile diagrams, we made visual representations of planting design and stand development, as basis for ‘expert’ assessment of four visual criteria: scale, diversity, naturalness and visual accessibility. The assessment was done for the young stage (0–25 years) and the mature stage (50–90 years) separately, using a qualitative three-step scale: limited, medium, and extended. Seven different planting design models were identified. Three of these originate from the urban paradigm: the seed source model, the density gradient model, and the habitat model. Another three originate from the nature-based paradigm: the natural succession model, the nature-based shortcut model, and the direct approach model. Only one model originates from the commercial paradigm: the monoculture model. The assessment showed that visual aspects vary considerably between planting designs and silvicultural systems. The monoculture model offers the splendour of the mature pillar hall with free views and movements, however, necessitating an obvious plantation stage in its youth. In contrast, models utilising succession and variation in species, age and tree spacing offers an extended experience of diversity and naturalness – even in the young stages. These visual qualities are discussed in relation to future perspectives for urban afforestation across urban woodland zones.     

Genetic selection indices for Swedish trotter broodmaresIndex de sélection pour les juments de trotteur suédoisGenetische selektionsindices für schwedische traber-zuchtstuten

Studbook performance records for 2734 Swedish standardbred trotter broodmares have been analysed. Transformation of most variables was necessary in order to approach normality of the records. The heritability for the traits varied between 0.10 and 0.68, the lowest value for transformed “number of starts” and highest for transformed “earnings per start”. Genetic correlations were very high or high between all traits except for transformed “number of starts”. Transformed “earnings” was found to be genetically almost identical with transformed “best life-time racing time”, but more suitable for selection purposes. Several selection indices were constructed and their use in mass-selection and for adjusting for non-random distribution of dam genotypes when progeny-testing stallions is discussed.