Biodiversity & Conservation

SS.CMU._.Beg

Explanation of sensitivity and recoverability


Physical Factors

Substratum Loss
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If the substratum is removed, Beggiatoa spp. mats will be removed along with it so that intolerance is high. However, if all conditions remain the same new mats are likely to rapidly re-form and recovery is set to very high.
Smothering
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Insufficient information
Increase in suspended sediment
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The biotope is likely to be relatively tolerant of an increase in siltation since there are no feeding or respiratory structures that could become clogged and growth of the bacterial mat should be unaffected.
Decrease in suspended sediment
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The biotope is likely to be relatively tolerant of a decrease in suspended sediment.
Desiccation
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This is a subtidal biotope so desiccation is not a relevant factor for consideration.
Increase in emergence regime
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CMU.Beg is a subtidal biotope so an increase in emergence is not relevant.
Decrease in emergence regime
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CMU.Beg is a subtidal biotope so an increase in emergence is not relevant.
Increase in water flow rate
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The biotope normally develops in areas of low water flow rate, such as sea lochs and fjords, where hypoxic or anoxic conditions are able to develop. Therefore, the biotope is likely to be highly intolerant of an increase in water flow that may bring supplies of oxygenated water allowing a more species rich biotope, typical of muddy substrata, to develop. Therefore, an intolerance of high but with a recoverability of very high has been recorded (see additional information below).
Decrease in water flow rate
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The biotope normally develops in areas of low water flow rate and so is likely to be relatively tolerant of a further decrease.
Increase in temperature
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Beggiatoa spp. mats have been reported from sulphur springs, deep water at ca 600m, fjords, coastal marine sediments, salt marshes, organic rich freshwater sediments, natural oil seeps and deep sea hydrothermal vents (e.g. Spies & Davis, 1979; Hagen & Nelson, 1997). There was no information found regarding the temperature requirements of Beggiatoa, and the temperature requirements of individual strains of the bacterium are likely to vary. However, given its occurrence in the vicinity of hydrothermal vents it is unlikely to be affected by increases in temperature at the benchmark level. In addition, Hiscock et al., (2001) suggested that increases in temperature as a result of global warming may result in more thermal stratification events in enclosed areas. Increased stratification will isolate deeper waters of sheltered sites and Beggiatoa spp. biotopes may occur where they not did previously exist. Therefore the biotope has been assessed as not sensitive.
Decrease in temperature
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There was no information found regarding the of reduced temperature on Beggiatoa spp. directly.
Increase in turbidity
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Beggiatoa is a heterotrophic bacteria that can grow in the dark and so growth will not be affected by low light conditions resulting from increased turbidity. The biotope is therefore, ranked as not sensitive to an increase in turbidity.
Decrease in turbidity
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Beggiatoa is a heterotrophic bacteria and so growth will not be affected by light conditions. The biotope is therefore, likely to be relatively tolerant of a decrease in turbidity.
Increase in wave exposure
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The biotope develops in areas of very little water movement so an increase in wave exposure is likely to wash the mats away. An intolerance rank of high is therefore recorded. If other conditions remain constant another mat is likely to form rapidly if wave exposure decreases again.
Decrease in wave exposure
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The biotope is only found in areas where there is no wave exposure so a decrease is not relevant.
Noise
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The biotope is not likely to be sensitive to noise.
Visual Presence
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The biotope is likely to be not sensitive to visual disturbance.
Abrasion & physical disturbance
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Mats of Beggiatoa form on soft mud and so are likely to be broken up by abrasion or physical disturbance. However, provided water flow rate and wave exposure remain constant mat fragments are likely to settle and continue growing. The bacteria produces a polysaccharide matrix that binds the bacteria together and to the substratum. Thus, an intolerance rank of low is recorded.
Displacement
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Removal of the organism, in mat form, to another place where conditions are the same is not likely to stop the growth of the bacteria or the mats that are formed. Therefore, a rank of not sensitive is recorded.

Chemical Factors

Synthetic compound contamination
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There is no information available regarding the impact of synthetic chemicals on Beggiatoa mats. However, Beggiatoa live in low or acidic pH environments so any chemicals that change pH may affect the biotope.
Heavy metal contamination
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There is no information available regarding the impact of heavy metals on Beggiatoa mats.
Hydrocarbon contamination
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In many areas around the world (e.g. see Spies & Davis, 1979) mats of Beggiatoa are associated with localized intense oil seepage and so the biotope is likely to be relatively tolerant of hydrocarbons.
Radionuclide contamination
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There is no information available regarding the impact of radionuclides on Beggiatoa mats.
Changes in nutrient levels
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Mats of Beggiatoa are usually associated with, and develop in the presence of high organic loading such as found under salmon farm cages (Lumb, 1989; Davies et al., 1996) and coastal areas of eutrophication (Graco et al., 2001). Therefore, an increase in nutrients will encourage the development of the bacterial mats.
Increase in salinity
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There is no information regarding the development of Beggiatoa mats in hypersaline waters. Freshwater strains and marine strains are different so a increase in salinity in brackish water sites may remove the freshwater strains of the bacterium, e.g. freshwater strains were unable to grow in salty conditions (Williams & Unz, 1989). However, if conditions of high nutrient and low oxygen concentration remain mats may then be formed by marine strains. Therefore, a rank of low intolerance, but with very low confidence is proposed in response to increased salinity.
Decrease in salinity
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Beggiatoa mats form in sewage waste water and in marine conditions. However, freshwater strains and marine strains are different so a decrease in salinity may remove the marine strains. (Freshwater strains for example, when tested were unable to grow in salty conditions (Williams & Unz, 1989)). However, if conditions of high nutrient and low oxygen concentration remain mats may then be formed by freshwater strains. Therefore, a rank of low intolerance, but with very low confidence is proposed in response to decreased salinity.
Changes in oxygenation
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Mats of Beggiatoa are usually associated with hypoxic or anoxic conditions (Diaz & Rosenberg, 1995; Connor et al., 1997). For example, during the autumn of 1993 and 1994 when the oxygen content of the bottom water in the Koljoford on the west coast of Sweden Beggiatoa mats covered the seafloor (Gustafsson & Nordberg, 1999). Therefore, the biotope is likely to be relatively tolerant of a decrease in oxygen concentration. In Maine coastal waters in the US the formation of Beggiatoa mats was linked to lack of oxygen when current speed was reduced for 2 h or longer during a tidal cycle. The formation of Beggiatoa mats only occurs when oxygen supply is reduced below the threshold level required to oxidize sedimented organic matter (Findlay, 2002).

Biological Factors

Introduction of microbial pathogens/parasites
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There are no known pathogens associated with Beggiatoa.
Introduction of non-native species
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There are no known non-native bacteria or species that compete with Beggiatoa.
Extraction
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It is extremely unlikely that Beggiatoa would be targeted for extraction and we have no evidence for the indirect effects of extraction of other species on this biotope.

Additional information icon Additional information

Recoverability
Bacterial colonies can spread rapidly via asexual reproduction. In many species resting stages, spores and cysts may occur which allows some bacteria to survive for long periods returning to normal growth when conditions are good. Beggiatoa is probably ubiquitous. Although growth rates of Beggiatoa are not known, the generation time for many bacteria is short (e.g. in some bacteria the population can double in 20 minutes). Therefore, in the right conditions a Beggiatoa mat is likely to develop very rapidly.

This review can be cited as follows:

Hill, J.M. 2002. Beggiatoa spp. on anoxic sublittoral mud. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 02/09/2014]. Available from: <http://www.marlin.ac.uk/habitatbenchmarks.php?habitatid=181&code=1997>