scholarly journals Does browning‐induced light limitation reduce fish body growth through shifts in prey composition or reduced foraging rates?

2020 ◽  
Vol 65 (5) ◽  
pp. 947-959
Author(s):  
Renee M. van Dorst ◽  
Anna Gårdmark ◽  
Richard Svanbäck ◽  
Magnus Huss
1998 ◽  
Vol 37 (2) ◽  
pp. 145-152 ◽  
Author(s):  
A. E. Nienhüser ◽  
P. Braches

Refilling of the Kerspe-Talsperre reservoir after restoration of the dam caused severe problems in water quality and supply due to a long-lasting ice-cover period and minimal precipitation. Unusually short spring overturn, high algal mass in spring and certainly the overflooding of the sediment, which had not been removed, caused a tremendous oxygen deficit in early summer. The whole hypolimnion turned anoxic and even in the metalimnion oxygen declined to a minimum. Manganese and iron reached high concentrations. Despite the poor water quality, raw water was urgently needed for the water supply and was pumped from the epilimnion during the clear water phase and in July when algal biomass was low. In the middle of August holomixis was induced artificially in order to improve water quality. The decline in algal production during and after artificial mixing was probably caused by light limitation of the algae.


2009 ◽  
Vol 102 (9) ◽  
pp. 1285-1296 ◽  
Author(s):  
Maud Le Gall ◽  
Mélanie Gallois ◽  
Bernard Sève ◽  
Isabelle Louveau ◽  
Jens J. Holst ◽  
...  

Sodium butyrate (SB) provided orally favours body growth and maturation of the gastrointestinal tract (GIT) in milk-fed pigs. In weaned pigs, conflicting results have been obtained. Therefore, we hypothesised that the effects of SB (3 g/kg DM intake) depend on the period (before v. after weaning) of its oral administration. From the age of 5 d, thirty-two pigs, blocked in quadruplicates within litters, were assigned to one of four treatments: no SB (control), SB before (for 24 d), or after (for 11–12 d) weaning and SB before and after weaning (for 35–36 d). Growth performance, feed intake and various end-point indices of GIT anatomy and physiology were investigated at slaughter. The pigs supplemented with SB before weaning grew faster after weaning than the controls (P < 0·05). The feed intake was higher in pigs supplemented with SB before or after weaning (P < 0·05). SB provided before weaning improved post-weaning faecal digestibility (P < 0·05) while SB after weaning decreased ileal and faecal digestibilities (P < 0·05). Gastric digesta retention was higher when SB was provided before weaning (P < 0·05). Post-weaning administration of SB decreased the activity of three pancreatic enzymes and five intestinal enzymes (P < 0·05). IL-18 gene expression tended to be lower in the mid-jejunum in SB-supplemented pigs. The small-intestinal mucosa was thinner and jejunal villous height lower in all SB groups (P < 0·05). In conclusion, the pre-weaning SB supplementation was the most efficient to stimulate body growth and feed intake after weaning, by reducing gastric emptying and intestinal mucosa weight and by increasing feed digestibility.


Author(s):  
Thassya C. dos Santos Schmidt ◽  
Doug E. Hay ◽  
Svein Sundby ◽  
Jennifer A. Devine ◽  
Guðmundur J. Óskarsson ◽  
...  

AbstractLife-history traits of Pacific (Clupea pallasii) and Atlantic (Clupea harengus) herring, comprising both local and oceanic stocks subdivided into summer-autumn and spring spawners, were extensively reviewed. The main parameters investigated were body growth, condition, and reproductive investment. Body size of Pacific herring increased with increasing latitude. This pattern was inconsistent for Atlantic herring. Pacific and local Norwegian herring showed comparable body conditions, whereas oceanic Atlantic herring generally appeared stouter. Among Atlantic herring, summer and autumn spawners produced many small eggs compared to spring spawners, which had fewer but larger eggs—findings agreeing with statements given several decades ago. The 26 herring stocks we analysed, when combined across distant waters, showed clear evidence of a trade-off between fecundity and egg size. The size-specific individual variation, often ignored, was substantial. Additional information on biometrics clarified that oceanic stocks were generally larger and had longer life spans than local herring stocks, probably related to their longer feeding migrations. Body condition was only weakly, positively related to assumingly in situ annual temperatures (0–30 m depth). Contrarily, body growth (cm × y−1), taken as an integrator of ambient environmental conditions, closely reflected the extent of investment in reproduction. Overall, Pacific and local Norwegian herring tended to cluster based on morphometric and reproductive features, whereas oceanic Atlantic herring clustered separately. Our work underlines that herring stocks are uniquely adapted to their habitats in terms of trade-offs between fecundity and egg size whereas reproductive investment mimics the productivity of the water in question.


2012 ◽  
Vol 69 (7) ◽  
pp. 1180-1193 ◽  
Author(s):  
Zachary W. Brown ◽  
Kevin R. Arrigo

Abstract Brown, Z. W., and Arrigo, K. R. 2012. Contrasting trends in sea ice and primary production in the Bering Sea and Arctic Ocean. – ICES Journal of Marine Science, 69: . Satellite remote sensing data were used to examine recent trends in sea-ice cover and net primary productivity (NPP) in the Bering Sea and Arctic Ocean. In nearly all regions, diminished sea-ice cover significantly enhanced annual NPP, indicating that light-limitation predominates across the seasonally ice-covered waters of the northern hemisphere. However, long-term trends have not been uniform spatially. The seasonal ice pack of the Bering Sea has remained consistent over time, partially because of winter winds that have continued to carry frigid Arctic air southwards over the past six decades. Hence, apart from the “Arctic-like” Chirikov Basin (where sea-ice loss has driven a 30% increase in NPP), no secular trends are evident in Bering Sea NPP, which averaged 288 ± 26 Tg C year−1 over the satellite ocean colour record (1998–2009). Conversely, sea-ice cover in the Arctic Ocean has plummeted, extending the open-water growing season by 45 d in just 12 years, and promoting a 20% increase in NPP (range 441–585 Tg C year−1). Future sea-ice loss will likely stimulate additional NPP over the productive Bering Sea shelves, potentially reducing nutrient flux to the downstream western Arctic Ocean.


2007 ◽  
Vol 4 (6) ◽  
pp. 985-1003 ◽  
Author(s):  
M. K. van der Molen ◽  
J. van Huissteden ◽  
F. J. W. Parmentier ◽  
A. M. R. Petrescu ◽  
A. J. Dolman ◽  
...  

Abstract. Carbon dioxide and methane fluxes were measured at a tundra site near Chokurdakh, in the lowlands of the Indigirka river in north-east Siberia. This site is one of the few stations on Russian tundra and it is different from most other tundra flux stations in its continentality. A suite of methods was applied to determine the fluxes of NEE, GPP, Reco and methane, including eddy covariance, chambers and leaf cuvettes. Net carbon dioxide fluxes were high compared with other tundra sites, with NEE=−92 g C m−2 yr−1, which is composed of an Reco=+141 g C m−2 yr−1 and GPP=−232 g C m−2 yr−1. This large carbon dioxide sink may be explained by the continental climate, that is reflected in low winter soil temperatures (−14°C), reducing the respiration rates, and short, relatively warm summers, stimulating high photosynthesis rates. Interannual variability in GPP was dominated by the frequency of light limitation (Rg<200 W m−2), whereas Reco depends most directly on soil temperature and time in the growing season, which serves as a proxy of the combined effects of active layer depth, leaf area index, soil moisture and substrate availability. The methane flux, in units of global warming potential, was +28 g C-CO2e m−2 yr−1, so that the greenhouse gas balance was −64 g C-CO2e m−2 yr−1. Methane fluxes depended only slightly on soil temperature and were highly sensitive to hydrological conditions and vegetation composition.


1994 ◽  
Vol 46 (1) ◽  
pp. 58-68 ◽  
Author(s):  
Susan J. Hazel ◽  
Callum M. Gillespie ◽  
Rob J. Moore ◽  
Ross G. Clark ◽  
Ken F. Jureidini ◽  
...  
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