Bottom Water Stagnation and Oxygen Depletion in a Scottish Sea Loch

Gillibrand, Phil; Turrell, W.R.; Moore, D.C.; Adams, R. D.

doi:10.1006/ecss.1996.0066

Cited by 34 publications

(20 citation statements)

References 16 publications

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“…Estimates of wastes have varied between 29 and 78% of input C, depending on the year (Pearson and Black 2001). A salmon farm with an annual production of 500 tonnes might use 750 tonnes of food in a year (1.5· annual production) with a C content of about 330 tonnes (Gillibrand et al 1996). Thus, Gillibrand et al (1996) concluded that the quantity of solid waste C from the farm, at 44% wastage released, is approximately 145 tonnes.…”

Section: Carbonmentioning

confidence: 97%

“…A salmon farm with an annual production of 500 tonnes might use 750 tonnes of food in a year (1.5· annual production) with a C content of about 330 tonnes (Gillibrand et al 1996). Thus, Gillibrand et al (1996) concluded that the quantity of solid waste C from the farm, at 44% wastage released, is approximately 145 tonnes. Estimates of C inputs suggest that fish farm feed may contribute up to 50% of the total particulate organic C supply (Gillibrand et al 1996).…”

Section: Carbonmentioning

confidence: 97%

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Effect of feed and feeding in the culture of salmonids on the marine aquatic environment: a synthesis for European aquaculture

et al. 2006

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While marine aquaculture has grown rapidly, so have concerns regarding the environmental impacts caused by the industry. In particular, increasing discharges of solid and dissolved fish excretions, nutrients and therapeutic chemicals have coincided with greater public awareness of the possibility of environmental damage. This has stimulated a number of criticisms, drawn from a wide spectrum of interests, ranging from the use of natural fish stocks to produce fish meal for aqua feeds to the effects of enhanced nutrient input on the coastal marine environment. The present study reviews available information on the environmental effects of feeding practices in salmonid aquaculture in Europe. Accumulation of waste food and fish faecal material results in changes in the sediment under fish cages, characterized by a low redox potential, high content of organic material and accumulation of nitrogenous and phosphorous compounds. Although significant environmental impacts have been reported in the literature at distances of up to 100 m from the cages, in general such impacts are reported to be localized to within 20-50 m around the cages. For farmed salmon and trout, mass balance models have been developed for nitrogen and phosphorus, indicating that 50% of the nitrogen and 28% of the phosphorus supplied with the food is wasted in dissolved form. The maximum nutrient release can be estimated from the hydrographic conditions in the immediate vicinity of the farm, such as water volume, tidal water exchange and currents. At present production levels, improvements in the feeding efficiency and Ó Springer Science+Business Media B.V. 2006 feed quality of aquafeeds could reduce waste and consequent environmental impacts.

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Section: Carbonmentioning

confidence: 97%

Section: Carbonmentioning

confidence: 97%

Effect of feed and feeding in the culture of salmonids on the marine aquatic environment: a synthesis for European aquaculture

et al. 2006

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“…In some cases the increase in carbon loading and accumulation result from allochthonous sources, such as organic waste from pulp mill factories (such as Idefjord, SwedenRosenberg, 1980 or Perdido Bay, Florida, USA -Flemer et al, 1999), fish aquaculture (such as Loch Ailort, Scotland - Gillibrand et al, 1996), or seafood processing plants (such as Saldanha Bay, South Africa - Christie and Moldan, 1977). It seems simple enough to remove the excess carbon inputs or to reduce nutrient loads to reverse the associated hypoxia.…”

Section: Reversal or Not Of Human-caused Hypoxiamentioning

confidence: 99%

Dynamics and distribution of natural and human-caused hypoxia

et al. 2010

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Abstract. Water masses can become undersaturated with oxygen when natural processes alone or in combination with anthropogenic processes produce enough organic carbon that is aerobically decomposed faster than the rate of oxygen reaeration. The dominant natural processes usually involved are photosynthetic carbon production and microbial respiration. The re-supply rate is indirectly related to its isolation from the surface layer. Hypoxic water masses (<2 mg L −1 , or approximately 30% saturation) can form, therefore, under "natural" conditions, and are more likely to occur in marine systems when the water residence time is extended, water exchange and ventilation are minimal, stratification occurs, and where carbon production and export to the bottom layer are relatively high. Hypoxia has occurred through geological time and naturally occurs in oxygen minimum zones, deep basins, eastern boundary upwelling systems, and fjords.Hypoxia development and continuation in many areas of the world's coastal ocean is accelerated by human activities, especially where nutrient loading increased in the Anthropocene. This higher loading set in motion a cascading set of events related to eutrophication. The formation of hypoxic areas has been exacerbated by any combination of interactions that increase primary production and accumulation of organic carbon leading to increased respiratory demand for oxygen below a seasonal or permanent pycnocline. Nutrient loading is likely to increase further as population growth and resource intensification rises, especially with increased Correspondence to: N. N. Rabalais (nrabalais@lumcon.edu) dependency on crops using fertilizers, burning of fossil fuels, urbanization, and waste water generation. It is likely that the occurrence and persistence of hypoxia will be even more widespread and have more impacts than presently observed.Global climate change will further complicate the causative factors in both natural and human-caused hypoxia. The likelihood of strengthened stratification alone, from increased surface water temperature as the global climate warms, is sufficient to worsen hypoxia where it currently exists and facilitate its formation in additional waters. Increased precipitation that increases freshwater discharge and flux of nutrients will result in increased primary production in the receiving waters up to a point. The interplay of increased nutrients and stratification where they occur will aggravate and accelerate hypoxia. Changes in wind fields may expand oxygen minimum zones onto more continental shelf areas. On the other hand, not all regions will experience increased precipitation, some oceanic water temperatures may decrease as currents shift, and frequency and severity of tropical storms may increase and temporarily disrupt hypoxia more often.The consequences of global warming and climate change are effectively uncontrollable at least in the near term. On the other hand, the consequences of eutrophication-induced hypoxia can be reversed if long-term, broad-scale, and per...

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“…Salmon farming is a common practice in high-latitude fjords and lochs. When flushing is restricted or infrequent, organic matter from the farms will sink to sediments and cause high oxygen consumption (Gillibrand et al, 1996), depleting the oxygen in bottom waters. In lochs such as Loch Ailort, subject to farming for several decades, the fish food may contribute up to 50% of the total particulate organic carbon (POC) supply.…”

Section: Fjordsmentioning

confidence: 99%

Effects of natural and human-induced hypoxia on coastal benthos

et al. 2009

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Abstract. Coastal hypoxia (defined here as <1.42 ml L −1 ; 62.5 µM; 2 mg L −1 , approx. 30% oxygen saturation) develops seasonally in many estuaries, fjords, and along open coasts as a result of natural upwelling or from anthropogenic eutrophication induced by riverine nutrient inputs. Permanent hypoxia occurs naturally in some isolated seas and marine basins as well as in open slope oxygen minimum zones. Responses of benthos to hypoxia depend on the duration, predictability, and intensity of oxygen depletion and on whether H 2 S is formed. Under suboxic conditions, large mats of filamentous sulfide oxidizing bacteria cover the seabed and consume sulfide. They are hypothesized to provide a detoxified microhabitat for eukaryotic benthic communities. Calcareous foraminiferans and nematodes are particularly tolerant of low oxygen concentrations and may attain high densities and dominance, often in association with microbial mats. When oxygen is sufficient to support metazoans, small, soft-bodied invertebrates (typically annelids), often with short generation times and elaborate branchial structures, predominate. Large taxa are more sensitive than small taxa to hypoxia. Crustaceans and echinoderms are typically more sensitive to hypoxia, with lower oxygen thresholds, than annelids, sipunculans, molluscs and cnidarians.

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Bottom Water Stagnation and Oxygen Depletion in a Scottish Sea Loch

Cited by 34 publications

References 16 publications

Effect of feed and feeding in the culture of salmonids on the marine aquatic environment: a synthesis for European aquaculture

Effect of feed and feeding in the culture of salmonids on the marine aquatic environment: a synthesis for European aquaculture

Dynamics and distribution of natural and human-caused hypoxia

Effects of natural and human-induced hypoxia on coastal benthos

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