scholarly journals Running the gauntlet: the predation environment of small fish in the northern Gulf of St Lawrence, Canada

2005 ◽  
Vol 62 (3) ◽  
pp. 412-416 ◽  
Author(s):  
Daniel E. Duplisea
Keyword(s):  
Body Size ◽  
North Sea ◽  
Prey Size ◽  
Small Fish ◽  
Size Spectra ◽  
Predator Prey ◽  
The North ◽  
Prefer Prey ◽  
Seal Population ◽  
The North Sea

Abstract Predation size spectra were constructed for the northern Gulf of St Lawrence, covering prey size ranges that include pre-recruit cod. Predation by fish and harp seals was modelled with a log-normally distributed predator–prey size ratio along with a relationship between predator body size and the energy required. Fish concentrate predation on prey of weight 0.5–2 g, whereas harp seals prefer prey of 60–125 g. It is speculated that predation caused by harp seals on pre-recruits could be a major factor limiting cod recruitment in the system. The northern Gulf of St Lawrence is a cold boreal system with a large predatory seal population, and cod recruit older than elsewhere. Therefore, cod recruitment may be more strongly affected by predation in the northern Gulf of St Lawrence than in warmer systems such as the North Sea, where recruitment is strongly influenced by temperature.

Sources and Fate of PCBs in the North Sea: A Review of Available Data

1991 ◽  
Vol 24 (10) ◽  
pp. 77-85 ◽  
Author(s):  
J. Klamer ◽  
R. W. P. M. Laane ◽  
J. M. Marquenie
Keyword(s):  
Adverse Effects ◽  
North Sea ◽  
German Bight ◽  
Marine Mammals ◽  
Wadden Sea ◽  
Annual Basis ◽  
The North ◽  
Total Input ◽  
Seal Population ◽  
The North Sea

From literature data it is calculated that on an annual basis, 11 to 17 tonnes of PCBs enter the North Sea. Largest sources are the Atlantic Ocean and the atmosphere: together they account for 60-79% of the total input. Sources with greatest impact are the rivers, sewers and sludge. Highest concentrations are found close to the Dutch shore and in the German Bight. The PCB levels result in adverse effects on the seal population in the Wadden Sea. Of the total world PCB production, at least 57% is still in use and their future dispersal into the oceans cannot easily be controlled. If the increase in ocean PCB concentration continues, it may ultimately result in the extinction of fish-eating marine mammals.

Controls on benthic biomass size spectra in shelf and deep-sea sediments – a modelling study

2011 ◽  
Vol 8 (4) ◽  
pp. 8189-8240 ◽  
Author(s):  
B. A. Kelly-Gerreyn ◽  
T. R. Anderson ◽  
B. J. Bett ◽  
A. P. Martin ◽  
J. I. Kaariainen
Keyword(s):  
Body Size ◽  
The Body ◽  
General Observation ◽  
Size Spectra ◽  
Size Classes ◽  
North East ◽  
The North ◽  
The North Sea ◽  
Wet Weight ◽  
Biomass Spectra

Abstract. Factors controlling biomass distributions in marine benthic organisms (meio- to macro-fauna, 1 μg–32 mg wet weight) were investigated through observations and allometric modelling. Biomass (and abundance) size spectra were measured at three locations: the Faroe-Shetland Channel in the north-east Atlantic (FSC, water depth 1600 m, September 2000); the Fladen Ground in the North Sea (FG, 150 m, September 2000); and the hypoxic Oman Margin (OM, 500 m, September 2002) in the Arabian Sea. Biomass increased with body size through a power law at FG (allometric exponent, b = 0.16) and at FSC (b = 0.32), but less convincingly at OM (b was not significantly different from −1/4 or 0). Our results question the assumption that metazoan biomass spectra are bimodal in marine sediments. The model incorporated 16 metazoan size classes, as derived from the observed spectra, all reliant on a common detrital food pool. All physiological (ingestion, mortality, assimilation and respiration) parameters scaled to body size following optimisation to the data at each site, the resulting values being consistent within expectations from the literature. For all sites, body size related changes in mortality played the greatest role in determining the trend of the biomass size spectra. The body size trend in the respiration rate was most sensitive to allometry in both mortality and ingestion, and the trend in body size spectra of the production: biomass ratio was explained by the allometry in ingestion. Our results suggest that size-scaling mortality and ingestion are important factors determining the distribution of biomass across the meiofauna to macrofauna size range in marine sedimentary communities, in agreement with the general observation that biomass tends to accumulates in larger rather than smaller size classes in these environments.

scholarly journals Benthic biomass size spectra in shelf and deep-sea sediments

2014 ◽  
Vol 11 (22) ◽  
pp. 6401-6416 ◽  
Author(s):  
B. A. Kelly-Gerreyn ◽  
A. P. Martin ◽  
B. J. Bett ◽  
T. R. Anderson ◽  
J. I. Kaariainen ◽  
...  
Keyword(s):  
Body Size ◽  
Atlantic Water ◽  
Scaling Exponent ◽  
Metabolic Theory ◽  
Size Spectra ◽  
Size Classes ◽  
The North ◽  
The North Sea ◽  
Wet Weight ◽  
Biomass Spectra

Abstract. The biomass distributions of marine benthic metazoans (meio- to macro-fauna, 1 μg–32 mg wet weight) across three contrasting sites were investigated to test the hypothesis that allometry can consistently explain observed trends in biomass spectra. Biomass (and abundance) size spectra were determined from observations made at the Faroe–Shetland Channel (FSC) in the Northeast Atlantic (water depth 1600 m), the Fladen Ground (FG) in the North Sea (150 m), and the hypoxic Oman Margin (OM) in the Arabian Sea (500 m). Observed biomass increased with body size as a power law at FG (scaling exponent, b = 0.16) and FSC (b = 0.32), but less convincingly at OM (b = 0.12 but not significantly different from 0). A simple model was constructed to represent the same 16 metazoan size classes used for the observed spectra, all reliant on a common detrital food pool, and allowing the three key processes of ingestion, respiration and mortality to scale with body size. A micro-genetic algorithm was used to fit the model to observations at the sites. The model accurately reproduces the observed scaling without needing to include the effects of local influences such as hypoxia. Our results suggest that the size-scaling of mortality and ingestion are dominant factors determining the distribution of biomass across the meio- to macrofaunal size range in contrasting marine sediment communities. Both the observations and the model results are broadly in agreement with the "metabolic theory of ecology" in predicting a quarter power scaling of biomass across geometric body size classes.

scholarly journals Benthic biomass size spectra in shelf and deep-sea sediments

2014 ◽  
Vol 11 (1) ◽  
pp. 901-942 ◽  
Author(s):  
B. A. Kelly-Gerreyn ◽  
A. P. Martin ◽  
B. J. Bett ◽  
T. R. Anderson ◽  
J. I. Kaariainen ◽  
...  
Keyword(s):  
Body Size ◽  
Atlantic Water ◽  
Scaling Exponent ◽  
Size Spectra ◽  
Size Classes ◽  
North East ◽  
The North ◽  
The North Sea ◽  
Wet Weight ◽  
Biomass Spectra

Abstract. The biomass distributions of marine benthic organisms (meio- to macro-fauna, 1 μg–32 mg wet weight) across three contrasting sites were investigated to test the hypothesis that allometry can consistently explain observed trends in biomass spectra. Biomass (and abundance) size spectra were determined from observations made at the Faroe–Shetland Channel in the north-east Atlantic (water depth 1600 m), the Fladen Ground in the North Sea (150 m), and the hypoxic Oman Margin (500 m) in the Arabian Sea. Observed biomass increased with body size as a power law at FG (scaling exponent, b = 0.16) and FSC (b = 0.32), but less convincingly at OM (b = 0.12 but not significantly different from 0). A simple model was constructed to represent the same 16 metazoan size classes used for the observed spectra, all reliant on a common detrital food pool, and allowing the three key processes of ingestion, respiration and mortality to scale with body size. A micro-genetic algorithm was used to fit the model to observations at the sites. The model accurately reproduces the observed scaling without recourse to including the effects of local influences such as hypoxia. Our results suggest that the size-scaling of mortality and ingestion are dominant factors determining the distribution of biomass across the meio- to macrofaunal size range in contrasting marine sediment communities. Both the observations and the model results are broadly in agreement with the "Metabolic Theory of Ecology" in predicting a quarter power scaling of biomass across geometric body size classes.

Structure of Pelagic Food Chain and Relationship Between Plankton and Fish Production

1977 ◽  
Vol 34 (12) ◽  
pp. 2344-2353 ◽  
Author(s):  
R. W. Sheldon ◽  
W. H. Sutcliffe Jr. ◽  
M. A. Paranjape
Keyword(s):  
North Sea ◽  
Gulf Of Maine ◽  
Standing Stock ◽  
Phytoplankton Production ◽  
Structural Elements ◽  
Pelagic Ecosystem ◽  
Predator Prey ◽  
The North ◽  
Plankton Production ◽  
The North Sea

Further observations on the standing stocks of pelagic organisms confirm the occurrence of approximately equal biomass over logarithmically equal size ranges. A simple theoretical framework is developed that shows that the structural elements of the pelagic ecosystem can be described in terms of the sizes of predator and prey and of the efficiencies of their interactions. In practice this means that if the standing stock at any size range is known, the standing stock at any other size can be estimated, and if the growth rate at this size is known, the production can be estimated. The theory is tested on three fisheries. For the Gulf of Maine and the North Sea, phytoplankton production is estimated from fishery production. For the area off Peru the fishery production is estimated from the plankton production. Key words: pelagic ecosystem, predator–prey relationships, plankton production, marine fisheries, Peru, North Sea, Gulf of Maine

scholarly journals Interpreting the large fish indicator for the Celtic Sea

2011 ◽  
Vol 68 (9) ◽  
pp. 1963-1972 ◽  
Author(s):  
Samuel Shephard ◽  
David G. Reid ◽  
Simon P. R. Greenstreet
Keyword(s):  
North Sea ◽  
Fish Community ◽  
Small Fish ◽  
Large Fish ◽  
The North ◽  
The North Sea ◽  
Celtic Sea ◽  
Using Data ◽  
Induced Changes ◽  
The Relationship

Abstract Shephard, S., Reid, D. G., and Greenstreet, S. P. R. 2011. Interpreting the large fish indicator for the Celtic Sea. – ICES Journal of Marine Science, 68: 1963–1972. The large fish indicator (LFI) was developed in the North Sea as a size-based indicator of fish community state. It is now established as OSPAR's fish community Ecological Quality Objective (EcoQO) metric and will be applied across all OSPAR regions. To produce a protocol for use when developing regional LFIs, the North Sea experience is interpreted using data from the Celtic Sea. Differences in fish community species composition and size distribution were reflected in a different species complex and large fish threshold (50 cm) for the Celtic Sea LFI. However, a lag of 12–14 years in the relationship between assemblage-averaged fishing mortality Fcom,y and the LFI suggested similar underlying ecological mechanisms to the North Sea. The indicator responded to changes in small fish biomass that follow fishing-induced changes in the level of predation by large demersal piscivores. The Celtic Sea LFI showed maximum observed values >0.40 before 1990, and 0.40 is here proposed as an EcoQO. Development of regional LFIs demands a flexible process rather than a strictly prescriptive protocol.

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