Influence of larval transport and temperature on recruitment dynamics of North Sea cod (Gadus morhua) across spatial scales of observation     

Giovanni Romagnoni  Kristina ie Kvile  Knut‐Frode Dagestad  Anne Maria Eikeset  Trond Kristiansen  Nils Chr. Stenseth   ystein Langangen 《Fisheries Oceanography》2020,29(4):324-339

The survival of fish eggs and larvae, and therefore recruitment success, can be critically affected by transport in ocean currents. Combining a model of early‐life stage dispersal with statistical stock–recruitment models, we investigated the role of larval transport for recruitment variability across spatial scales for the population complex of North Sea cod (Gadus morhua). By using a coupled physical–biological model, we estimated the egg and larval transport over a 44‐year period. The oceanographic component of the model, capable of capturing the interannual variability of temperature and ocean current patterns, was coupled to the biological component, an individual‐based model (IBM) that simulated the cod eggs and larvae development and mortality. This study proposes a novel method to account for larval transport and success in stock–recruitment models: weighting the spawning stock biomass by retention rate and, in the case of multiple populations, their connectivity. Our method provides an estimate of the stock biomass contributing to recruitment and the effect of larval transport on recruitment variability. Our results indicate an effect, albeit small, in some populations at the local level. Including transport anomaly as an environmental covariate in traditional stock–recruitment models in turn captures recruitment variability at larger scales. Our study aims to quantify the role of larval transport for recruitment across spatial scales, and disentangle the roles of temperature and larval transport on effective connectivity between populations, thus informing about the potential impacts of climate change on the cod population structure in the North Sea.  相似文献   

Effects of light and short-term temperature elevation on the 48-h hatching success of cold-stored Acartia tonsa Dana eggs     

Andreas Hagemann  Gunvor Øie  Jan Ove Evjemo  Yngvar Olsen 《Aquaculture International》2016,24(1):57-68

The effects of light and short-term temperature elevation on the 48-h egg hatching success (HS) of cold-stored (2 °C) Acartia tonsa Dana (Copepoda: Calanoida) eggs were examined in the present study. The eggs can be stored for up to 7.5 months and maintain their high hatching rate under optimal conditions. Intensively produced eggs from the copepod A. tonsa may be hatched and used as an inoculum for producing copepod nauplii as live feed for fish larvae. The HS for eggs that were directly exposed to LED light declined rapidly after 1 month of storage (from 91 to 25 %), and these eggs did not hatch at all after 3 months of storage. The highest HS found was for eggs stored in complete darkness. The HS for eggs stored in normoxic (≥7 mg DO L^?1) and anoxic (≤0.03 mg DO L^?1) seawater was not affected by short-term temperature transitions from 2 °C up to 9 or 17 °C for a period of 12 or 24 h, when hatched 1 week post-exposure. The global mean HS for eggs stored in normoxic seawater was 85.9 % and significantly lower compared to eggs stored under anoxic conditions after 3 weeks of storage (91.8 %) (P = 0.001; SNK).  相似文献   

Can plot edge bias be reduced by means of airborne laser scanning?     

Rune Østergaard Pedersen 《Scandinavian Journal of Forest Research》2016,31(2):206-221

This paper presents new methods for plot edge bias (PEB) correction of individual tree competition indices (CIs) using airborne laser scanning (ALS) as auxiliary information in multivariate ratio and multivariate regression models. I applied the methods to 557 plots from the Norwegian National Forest Inventory located in Hedmark County in South East Norway and compared them to the benchmarks methods linear expansion and simulated annealing by studying the individual tree growth predictions before and after PEB correction. Generally, the simulated annealing method seemed to improve growth prediction most and overall the existing methods performed better than those based on ALS. All PEB-correction methods tested gave minor changes in growth predictions and the absolute change in percent in adj. R² and Akaike's Information Criterion (AIC) was numerically small, with an average percentage change for the tested CIs between 1.8 for adj. R² and 0.6 for AIC of the observed values in the original data. The small differences in the results between the original data and the PEB-corrected data show that on average PEB remains a minor problem for individual tree growth prediction. Whether the results are valid for forests with significantly different spatial composition than that of this database remains to be confirmed.  相似文献   

Invasion potential of Agrilus planipennis and other Agrilus beetles in Europe: import pathways of deciduous wood chips and MaxEnt analyses of potential distribution areas          下载免费PDF全文

D. Flø  P. Krokene  B. Økland 《EPPO Bulletin》2015,45(2):259-268

Bark‐ and wood‐boring beetles in the genus Agrilus (Coleoptera: Buprestidae) can survive wood‐chipping, and Agrilus planipennis has established in North America and European Russia with devastating impacts on forest ecosystems. The work presented in this paper combined import statistics of deciduous wood chips, Maximum entropy modelling (MaxEnt) of climatic similarities, and the distribution of potential tree hosts to predict the likelihood of four selected North American Agrilus species to become introduced and established in Europe. In agreement with the EU's energy‐policy target of increased use of wood chips, there was a linear or exponential increase in European imports of deciduous wood chips during the past 10 years from countries harbouring potentially harmful Agrilus species. MaxEnt showed high environmental suitability in Europe for the four selected Agrilus species, particularly in Eastern Europe and European Russia for A. anxius, A. bilineatus and A. planipennis and in southern Europe for A. politus. Documented susceptible host trees are widely distributed in the predicted areas of Agrilus distribution in Europe, and these areas receive large quantities of deciduous wood chips from countries where these and other Agrilus species are present. Thus, it was concluded that the fundamental conditions for introduction and establishment of Agrilus species in Europe are in place.  相似文献   

Fiscal Decentralization and Economic Growth in Central and Eastern Europe     

ANDRÉS RODRÍGUEZ‐POSE  ANNE KRØIJER 《Growth and change》2009,40(3):387-417

The majority of the literature on fiscal decentralization has tended to stress that the greater capacity of decentralized governments to tailor policies to local preferences and to be innovative in the provision of policies and public services, the greater the potential for economic efficiency and growth. There is, however, little empirical evidence to substantiate this claim. In this paper we examine, using a panel data approach with dynamic effects, the relationship between the level of fiscal decentralization and economic growth rates across 16 Central and Eastern European countries over the 1990–2004 period. Our findings suggest that, contrary to the majority view, there is a significant negative relationship between two out of three fiscal decentralization indicators included in the analysis and economic growth. However, the use of different time lags allows us to nuance this negative view and show that long‐term effects vary depending on the type of decentralization undertaken in each of the countries considered. While expenditure at and transfers to sub‐national tiers of government are negatively correlated with economic growth, taxes assigned at the sub‐national level evolve from having a significantly negative to a significantly positive correlation with the national growth rate. This supports the view that sub‐national governments with their own revenue source respond better to local demands and promote greater economic efficiency  相似文献   

Testing a model to track fish migrations in polar regions using pop‐up satellite archival tags     

CEDAR M. CHITTENDEN  BJØRN ÅDLANDSVIK  OLE‐PETTER PEDERSEN  DAVID RIGHTON  AUDUN H. RIKARDSEN 《Fisheries Oceanography》2013,22(1):1-13

The use of pop‐up archival satellite tags (PSATs) to geolocate marine fishes in polar regions is challenging due to the brevity of periods during which there is a defined sunrise and sunset. Models using other environmental parameters are thus required to supplement geolocation data in the estimation of marine migratory routes. The objective of this work was to create a simple method that would estimate the migratory pathways of Atlantic salmon (Salmo salar) in polar regions using temperature and depth recordings. Validated geolocations from PSATs were used to test and constrict the model. The model’s predicted migratory routes were within 100 km of the light‐based geolocations calculated by the tags. By constraining the trajectories through the geolocations, bias was reduced. Sensitivity analyses demonstrated that slight alterations of the location and timing of the start and end points did not affect the mean migratory route estimates. This method is a management tool that can determine the primary habitat areas for any surface‐ or bottom‐dwelling marine species – especially in polar regions, where other methods may be impossible.  相似文献   

Dietary phosphorus does not reduce the risk for spinal deformities in a model of adjuvant‐induced inflammation in Atlantic salmon (Salmo salar) postsmolts     

L. GIL MARTENS  P.G. FJELLDAL  E.‐J. LOCK  A. WARGELIUS  H. WERGELAND  P.E. WITTEN  T. HANSEN  R. WAAGBØ  R. ØRNSRUD 《Aquaculture Nutrition》2012,18(1):12-20

Inflammation is a non‐specific protective mechanism towards injury known to affect bone remodelling. This study aimed to investigate the effect of Freund’s complete adjuvant (FCA) induced‐inflammation on the prevalence of spinal deformities of Atlantic salmon postsmolts fed with two different dietary P levels. Sextuple groups of salmon postsmolts were fed with either a low‐phosphorous (6 g kg^?1 available P, LP) or a high‐phosphorous (9 g kg^?1 available P) diet for a period of 101 days. On Day 102, individually tagged fish were subjected to (i) single injection with FCA (0.125 mg kg^?1 BW) dissolved in phosphate‐buffered saline (PBS) (ii) placebo injection with PBS or (iii) sham injection (insertion of needle only) or (iv) remained untreated. On Day 103, fish were given a common diet for 174 days in seawater. No significant differences in body weight were observed. Injected fish, particularly the FCA group, had more compressions in the injection site than untreated fish. No effect of diet and no interaction between treatment and diet were observed. Severe scoliosis was observed in ～7% of FCA‐injected individuals, corresponding to a mixture of bone malformations in the tail region. In conclusion, experimentally induced inflammation may be an independent risk factor for bone deformities in Atlantic salmon.  相似文献   

Effects of feed processing conditions and acid salts on nutrient digestibility and physical quality of soy‐based diets for Atlantic salmon (Salmo salar)     

T. MORKEN  O. F. KRAUGERUD  M. SØRENSEN  T. STOREBAKKEN  M. HILLESTAD  R. CHRISTIANSEN  M. ØVERLAND 《Aquaculture Nutrition》2012,18(1):21-34

Two experiments were conducted to investigate effects of feed processing conditions and potassium diformate (KDF) supplementation on apparent digestibility of nutrients in Atlantic salmon (Salmo salar) and physical quality of extruded feed. In Exp. 1, diets with raw or expander pretreated full‐fat soybean meal (FFSBM) at 100 or 120 °C were extruded at 110 °C. Expander pretreatment significantly (P < 0.05) improved the digestibility of arginine, glutamine and tyrosine in Atlantic salmon. The higher digestibility of expander pretreated FFSBM was confirmed in mink (Mustela vison). In Exp. 2, diets with defatted soybean meal (SBM) were extruded at 110, 130 or 150 °C. The results showed that increasing extrusion temperatures significantly (P < 0.05) improved the digestibility of most major nutrients and amino acids in Atlantic salmon. In general, KDF supplementation to FFSBM and SBM diets did not affect digestibility of nutrients in Atlantic salmon or mink. Expander pretreatment and increasing extrusion temperatures increased pellet expansion, while KDF supplementation reduced pellet expansion.  相似文献   

Short-term effects of hardened wood ash and nitrogen fertilisation in a Norway spruce forest on soil solution chemistry and humus chemistry studied with different extraction methods     

Nicholas Clarke  Tonje Økland  Kjersti Holt Hanssen  Jørn-Frode Nordbakken  Katarzyna Wasak 《Scandinavian Journal of Forest Research》2018,33(1):32-39

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Effects of forest residue harvesting on short-term changes in soil solution chemistry     

Nicholas Clarke  Silje Skår  O. Janne Kjønaas  Kjersti Holt Hanssen  Tonje Økland  Jørn-Frode Nordbakken 《Scandinavian Journal of Forest Research》2018,33(3):299-307

Short-term (three to four years) effects of forest harvesting on soil solution chemistry were investigated at two Norway spruce sites in southern Norway, differing in precipitation amount and topography. Experimental plots were either harvested conventionally (stem-only harvesting, SOH) or whole trees, including crowns, twigs and branches were removed (whole-tree harvesting, WTH), leaving residue piles on the ground for some months before removal. The WTH treatment had two sub-treatments: WTH-pile where there had been piles and WTH-removal, from where residues had been removed to make piles. Increased soil solution concentrations of NO₃–N, total N, Ca, Mg and K at 30?cm depth, shown by peaks in concentrations in the years after harvesting, were found at the drier, less steep site in eastern Norway after SOH and WTH-pile, but less so after WTH-removal. At the wetter, steeper site in western Norway, peaks were often observed also at WTH-removal plots, which might reflect within-site differences in water pathways due largely to site topography.  相似文献