scholarly journals Beach morphology and food web structure: comparison of an eroding and an accreting sandy shore in the North Sea

2002 ◽  
Vol 56 (3) ◽  
pp. 177-189 ◽  
Author(s):  
Iris Menn
Keyword(s):  
Food Web ◽  
North Sea ◽  
Food Web Structure ◽  
Structure Comparison ◽  
Beach Morphology ◽  
Sandy Shore ◽  
The North ◽  
Web Structure ◽  
The North Sea

Large-scale responses of nematode communities to chronic otter-trawl disturbance

2008 ◽  
Vol 65 (4) ◽  
pp. 723-732 ◽  
Author(s):  
Hilmar Hinz ◽  
Jan G Hiddink ◽  
James Forde ◽  
Michel J Kaiser
Keyword(s):  
Food Web ◽  
North Sea ◽  
Large Scale ◽  
Life Cycles ◽  
Irish Sea ◽  
Otter Trawl ◽  
Food Web Structure ◽  
Nematode Communities ◽  
The North ◽  
The North Sea

Nematodes, because of their small size and short life cycles, are thought to be less affected by direct trawling mortality compared with the larger macrofauna. However, nematodes may still be indirectly affected by the physical disturbance of trawling through changing sediment characteristics and food web structure. We determined whether nematode communities on two muddy fishing grounds located in the North Sea and Irish Sea were affected by chronic otter-trawl disturbance and quantified these effects. Nematode abundance, production, and genus richness declined in response to trawling within both areas. Nematode biomass did not respond to trawling intensity. Genus composition was affected by trawling only in the North Sea. The responses in abundance of individual nematode genera to increasing trawling intensity were negative as well as positive. These results indicate that despite their size and fast life cycle, nematodes are affected by intensive trawling on muddy fishing grounds. The loss in secondary production from nematodes can have far-reaching consequences for the integrity of the benthic food web. As bottom trawl fisheries are expanding into ever deeper muddy habitats, the results presented here are an important step towards understanding the global ecosystem effects of bottom trawling.

scholarly journals Food web structure variability in the surface layer, at a fixed station influenced by the North Western Mediterranean Current

Hydrobiologia ◽  
1996 ◽  
Vol 321 (2) ◽  
pp. 145-153 ◽  
Author(s):  
Urania Christaki ◽  
France Van Wambeke ◽  
Epaminondas D. Christou ◽  
Pascal Conan ◽  
Raymond Gaudy
Keyword(s):  
Surface Layer ◽  
Food Web ◽  
Western Mediterranean ◽  
Food Web Structure ◽  
The North ◽  
Web Structure ◽  
North Western ◽  
Fixed Station

Feeding, Growth and Reproduction of the Marine Planktonic Copepod Pseudo-Calanus Elongatus Boeck

1976 ◽  
Vol 56 (2) ◽  
pp. 327-344 ◽  
Author(s):  
G.-A. Paffenhöfer ◽  
R. P. Harris
Keyword(s):  
Food Web ◽  
North Sea ◽  
Calanoid Copepods ◽  
Small Copepod ◽  
The North ◽  
Controlled Conditions ◽  
Food Concentrations ◽  
Food Species ◽  
The North Sea ◽  
Growth And Reproduction

INTRODUCTIONThe development of techniques to culture calanoid copepods over multiple generations in the laboratory has resulted in considerable advances in knowledge about a group of animals of major importance in the marine food web. A series of extensive studies have been made of two species of large calanoids, Calanus helgolandicus (Claus) (Mullin & Brooks, 1967, 1970a, 1970b; Paffenhöfer, 1970, 1971, 1976a, 1976b), and Rhincalanus nasutus Giesbrecht (Mullin & Brooks, 1967, 1970a, 1970b). Feeding, growth, and reproduction have been studied under controlled conditions, using different temperatures, food species, and food concentrations. Some of the information gained in these studies has been incorporated into a simulation model of the planktonic ecosystem of the North Sea (Steele, 1974). However, in the North Sea and in many other sea areas species of small copepod probably form an important component of the food web. Little information is available on the quantitative biology of these small copepods under controlled conditions.

Decadal changes in the North Sea food web between 1981 and 1991 — implications for fish stock assessment

2006 ◽  
Vol 63 (11) ◽  
pp. 2586-2602 ◽  
Author(s):  
Alexander Kempf ◽  
Jens Floeter ◽  
Axel Temming
Keyword(s):  
Food Web ◽  
North Sea ◽  
Fish Stock ◽  
Fish Diet ◽  
Data Set ◽  
The North ◽  
Stock Biomass ◽  
Spawning Stock ◽  
The North Sea ◽  
The Impact

The North Sea ecosystem of the early 1980s differed substantially from that of the early 1990s. The current North Sea multispecies fisheries assessment models are parameterized by fish diet data sets that reflect both ecosystem states, as the stomachs were sampled in 1981 and 1991. In this study, multispecies virtual population analysis (MSVPA) was parameterized with either diet data set, leading to different model food webs, each representing the predator's diet selection behavior and spatiotemporal overlap with their prey in the two respective ecosystem states. The impact of these changes in predator preferences and spatiotemporal overlap on recruitment success and on stock developments could be demonstrated by using either stomach data set to estimate historic and future spawning stock biomass and recruitment trajectories. The observed changes in the food web mainly impacted the hindcasted recruitment trajectories, whereas spawning stock biomass estimates were quite robust. In the prediction runs, the differences in the survival rate of the recruits decided whether fish stocks of commercially important species (e.g., Gadus morhua, Merlangius merlangus) would recover or collapse in the near future.

Introduction into the ecosystem of the North Sea: Hydrography, biota, and food web relationships

1992 ◽  
Vol 26 (1) ◽  
pp. 7-18 ◽  
Author(s):  
P. A. W. J. Wilde ◽  
M. I. Jenness ◽  
G. C. A. Duineveld
Keyword(s):  
Food Web ◽  
North Sea ◽  
The North ◽  
The North Sea

scholarly journals Estimation of predator-prey mass ratios using stable isotopes: sources of errors

2014 ◽  
Author(s):  
Eric Hertz ◽  
James Robinson ◽  
Marc Trudel ◽  
Asit Mazumder ◽  
Julia K Baum
Keyword(s):  
Stable Isotopes ◽  
Food Web ◽  
North Sea ◽  
Trophic Position ◽  
Trophic Levels ◽  
Environmental Stability ◽  
Food Web Structure ◽  
Predator Prey ◽  
Web Structure ◽  
Prey Mass

In aquatic systems, the ratio of predator mass to prey mass (PPMR) is an important constraint on food web structure, and has been correlated with environmental stability. One common approach of estimating PPMR uses nitrogen stable isotopes (δ15N) as an indicator of trophic position, under the assumption that the discrimination between diet and tissue is constant with increasing diet δ15N (an additive approach). However, recent studies have shown that this assumption may not be valid, and that there is a negative trend between the δ15N of the diet and the discrimination value (a scaled approach). We estimated PPMR for a simulated food web using the traditional additive approach and improved scaled approach, before testing our predictions with isotope samples from a North Sea food web. Our simulations show that the additive approach gives incorrect estimates of PPMR, and these biases are reflected in North Sea PPMR estimates. The extent of the bias is dependent on the baseline δ15N and trophic level sampled, with the greatest differences for samples with low baseline δ15N sampled at lower trophic levels. The scaled approach allows for the comparison of PPMR across varying δ15N baselines and trophic levels, and will refine estimates of PPMR.

scholarly journals North Sea ecosystem change from swimming crabs to seagulls

2012 ◽  
Vol 8 (5) ◽  
pp. 821-824 ◽  
Author(s):  
C. Luczak ◽  
G. Beaugrand ◽  
J. A. Lindley ◽  
J-M. Dewarumez ◽  
P. J. Dubois ◽  
...  
Keyword(s):  
Food Web ◽  
North Sea ◽  
Terrestrial Ecosystems ◽  
Ecosystem Change ◽  
Sea Temperature ◽  
The North ◽  
The North Sea ◽  
Important Food Source ◽  
Induced Changes ◽  
Swimming Crabs

A recent increase in sea temperature has established a new ecosystem dynamic regime in the North Sea. Climate-induced changes in decapods have played an important role. Here, we reveal a coincident increase in the abundance of swimming crabs and lesser black-backed gull colonies in the North Sea, both in time and in space. Swimming crabs are an important food source for lesser black-backed gulls during the breeding season. Inhabiting the land, but feeding mainly at sea, lesser black-backed gulls provide a link between marine and terrestrial ecosystems, since the bottom-up influence of allochthonous nutrient input from seabirds to coastal soils can structure the terrestrial food web. We, therefore, suggest that climate-driven changes in trophic interactions in the marine food web may also have ensuing ramifications for the coastal ecology of the North Sea.

scholarly journals Broad-scale trophic shift in the pelagic North Pacific revealed by an oceanic seabird

2017 ◽  
Vol 284 (1851) ◽  
pp. 20162436 ◽  
Author(s):  
Peggy H. Ostrom ◽  
Anne E. Wiley ◽  
Helen F. James ◽  
Sam Rossman ◽  
William A. Walker ◽  
...  
Keyword(s):  
Amino Acid ◽  
Food Web ◽  
North Pacific ◽  
Food Web Structure ◽  
The North ◽  
Web Structure ◽  
Geographical Scale ◽  
The North Pacific ◽  
Broad Scale ◽  
Millennial Scale

Human-induced ecological change in the open oceans appears to be accelerating. Fisheries, climate change and elevated nutrient inputs are variously blamed, at least in part, for altering oceanic ecosystems. Yet it is challenging to assess the extent of anthropogenic change in the open oceans, where historical records of ecological conditions are sparse, and the geographical scale is immense. We developed millennial-scale amino acid nitrogen isotope records preserved in ancient animal remains to understand changes in food web structure and nutrient regimes in the oceanic realm of the North Pacific Ocean (NPO). Our millennial-scale isotope records of amino acids in bone collagen in a wide-ranging oceanic seabird, the Hawaiian petrel ( Pterodroma sandwichensis ), showed that trophic level declined over time. The amino acid records do not support a broad-scale increase in nitrogen fixation in the North Pacific subtropical gyre, rejecting an earlier interpretation based on bulk and amino acid specific δ 15 N chronologies for Hawaiian deep-sea corals and bulk δ 15 N chronologies for the Hawaiian petrel. Rather, our work suggests that the food web structure in the NPO has shifted at a broad geographical scale, a phenomenon potentially related to industrial fishing.

scholarly journals Spatial heterogeneity in the structure of the planktonic food web in the North Sea

1998 ◽  
Vol 168 ◽  
pp. 197-211 ◽  
Author(s):  
K Richardson ◽  
TG Nielsen ◽  
FB Pedersen ◽  
JP Heilmann ◽  
B Løkkegaard ◽  
...  
Keyword(s):  
Spatial Heterogeneity ◽  
Food Web ◽  
North Sea ◽  
The North ◽  
Planktonic Food ◽  
The North Sea
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