Beggiatoa spp. on anoxic sublittoral mud

17-05-2002
Researched byJacqueline Hill Refereed byThis information is not refereed.
EUNIS CodeA5.7211 EUNIS NameBeggiatoa spp. on anoxic sublittoral mud

Summary

UK and Ireland classification

EUNIS 2008A5.7211Beggiatoa spp. on anoxic sublittoral mud
EUNIS 2006A5.7211Beggiatoa spp. on anoxic sublittoral mud
JNCC 2004SS.SMu.IFiMu.BegBeggiatoa spp. on anoxic sublittoral mud
1997 BiotopeSS.CMU._.BegBeggiatoa spp. on anoxic sublittoral mud

Description

Sublittoral soft anoxic mud, often in areas with poor water exchange with the open sea, can have a conspicuous bacterial mat covering of Beggiatoa species. The anoxia may be a result of natural conditions of poor water exchange in some sea lochs (and many Scandinavian fjords) or artificially under fish farm cages from nutrient enrichment. The fauna is normally impoverished at such sites, with few elements of the infaunal communities present in other muddy biotopes. Scavenging species such as Asterias rubens and Carcinus maenas are typically present where the habitat is not too anoxic but in extreme conditions of anoxia little survives other than the Beggiatoa. The polychaete Ophiodromus flexuosus occurs in high densities at the interface between oxygenated and deoxygenated sediments (in Norwegian fjords). (Information taken from the Marine Biotope Classification for Britain and Ireland, Version 97.06: Connor et al., 1997a, b).

Recorded distribution in Britain and Ireland

Recorded on the coast of the Shetland Isles and the west coast of Scotland. Also recorded in South Donegal Bay in Ireland. Often a feature of the seabed below fish cages in sheltered locations.

Depth range

-

Additional information

None entered

Listed By

Further information sources

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JNCC

Habitat review

Ecology

Ecological and functional relationships

Mats of the sulphur reducing, filamentous bacteria Beggiatoa spp. occur at sites of organic pollution, often in areas of soft anoxic mud where there is poor water exchange with the open sea. Beggiatoa mats occur on the surface of the sediment at the hypoxic/anoxic interface. Beggiatoa sp. are characterized by their gliding motility, lack of photosynthetic pigments, and the presence of sulphur globules around the cytoplasm (Hagen & Nelson, 1997). The underlying sediment is primarily depauperate, the low oxygen levels resulting in death or loss of most mega and macrofauna. A few tolerant polychaetes, gastrotrichs, and nematodes may occur (e.g. see Bernhard et al., 2000). The Beggiatoa excludes other heterotrophic bacteria and most other macrofauna, with few elements of the infaunal communities that are found in other muddy biotopes.

Beggiatoa sp. utilize sulphides leaching from the sediment, and oxidize them to sulphate to liberate energy for growth but also require simple organic acids and alcohols for growth (Williams & Unz, 1989; Hagen & Nelson, 1997).The other organisms present (e.g. ciliates, nematodes and euglenoid flagellates) are probably decomposers, feeding on organic matter. However, Bernhard et al. (2000) noted several species of protist contained symbiotic bacteria that were presumably chemoautotrophs. The sediment below the mats is populated by chemoautotrophic bacteria, that remineralize organic matter, producing methane, or sulphides of hydrogen (H2S), iron or manganese and are probably very similar to microbial communities found at depth in other sediments (for summary see Davies et al., 1996).

The few remaining tolerant species are probably deposit feeders on the microbial rich sediment or scavengers (e.g. crabs, hermit crabs, and starfish) feeding on dead or dying fauna.

Seasonal and longer term change

The development of Beggiatoa mats are related to environmental conditions such as organic input and oxygen content which may have seasonal trends in some areas. Anoxic conditions may also develop in deep water due to the presence of a thermocline in the summer months e.g. some Fjords (Diaz & Rosenberg, 1995; Gustafsson & Nordberg, 1999) and Aberiddy Quarry (Hiscock & Hoare, 1973).

Habitat structure and complexity

The biotope has little structural complexity because the surface of the sediment is covered with a mat of the filamentous bacteria reducing access to sediments for infaunal organisms. Scavenging species such as Asterias rubens and Carcinus maenas are typically present where the habitat is not too anoxic but in extreme conditions of anoxia little survives other than the Beggiatoa. The polychaete Ophiodromus flexuosus occurs in high densities at the interface between oxygenated and deoxygenated sediments (in Norwegian fjords). The mats provide habitat for an abundant meiofaunal community (Bernhard et al., 2000) such as nematodes and small ciliates (Spies & Davis, 1979). The combination of anoxic conditions and the related production of sulphides (e.g. H2S) is highly toxic to most life (see Diaz & Rosenberg, 1995) and the underlying sediment may be effectively abiotic. Where conditions are not anoxic but severely hypoxic, Beggiatoa may be patchy, with an impoverished infauna present.

Productivity

Productivity in this biotope is limited to the anaerobic chemoautotrophic productivity of infaunal bacteria and of the sulphur-oxidising bacteria Beggiatoa sp. Beggiatoa sp. utilize sulphides leaching from the sediment, and oxidize them to sulphate to liberate energy for growth but also require simple organic acids and alcohols for growth (Williams & Unz, 1989; Hagen & Nelson, 1997). Diaz & Rosenberg (1995) noted that area dominated by bacterial mats, the benthic-pelagic coupling is weakened and the food chain shortened. However, they also noted that bacterial mats may be important sources of organic matter in coastal upwelling oxygen minimum zones.

Recruitment processes

Bacterial colonies can spread rapidly via asexual reproduction. In many species resting stages, spores and cysts may occur that allow some bacteria to survive for long periods returning to normal growth when conditions are good. Beggiatoa sp. are probably ubiquitous.

Time for community to reach maturity

Although growth rates of Beggiatoa in natural environments are not known, the generation time for many bacteria is short and growth is usually exponential in optimal conditions (e.g. in some bacteria the population can double in 20 minutes). Therefore, in the right conditions, a Beggiatoa mat is likely to develop rapidly.

Additional information

None entered.

Preferences & Distribution

Recorded distribution in Britain and IrelandRecorded on the coast of the Shetland Isles and the west coast of Scotland. Also recorded in South Donegal Bay in Ireland. Often a feature of the seabed below fish cages in sheltered locations.

Habitat preferences

Depth Range
Water clarity preferences
Limiting Nutrients Not relevant
Salinity
Physiographic
Biological Zone
Substratum
Tidal
Wave
Other preferences High organic content, low oxygen and sulphides

Additional Information

Mats of Beggiatoa spp. occur on the surface of organic rich, anoxic sediments, at the hypoxic/anoxic interface, and oxidize sulphides to sulphates. For example Bernhard et al. (2000) reported mats of Beggiatoa spp. on the surface of sediments at a depth of ca 600m, in which the oxygen concentration was < 1µM (ca 0.02 µl/l) in the top 2-3 cm of sediment and sulphide concentrations were >0.1 µM.

Species composition

Species found especially in this biotope

  • Beggiatoa sp.

Rare or scarce species associated with this biotope

-

Additional information

The MNCR recorded 149 species in records of this biotope. However, only scavenging Carcinus maenas and Asterias rubens were recorded as common. Numerous other species occur at low abundance or in only a few records of the biotope, probably reflecting the patchy nature of the Beggiatoa spp. mats.

Sensitivity reviewHow is sensitivity assessed?

Explanation

This biotope is characterized by mats of the bacterium Beggiatoa spp. Since no or very few other macrofaunal species at least are present in the biotope the sensitivity of Beggiatoa is probably representative of the sensitivity of the whole biotope.

Species indicative of sensitivity

Community ImportanceSpecies nameCommon Name
Important characterizingBeggiatoaA bacterium

Physical Pressures

 IntoleranceRecoverabilitySensitivitySpecies RichnessEvidence/Confidence
High Very high Low No change Low
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.
No information No information No information Insufficient
information
Not relevant
Insufficient
information
Tolerant Not relevant Not relevant No change Moderate
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.
Tolerant Very high Not sensitive* No change Very low
The biotope is likely to be relatively tolerant of a decrease in suspended sediment.
Not relevant Not relevant Not relevant Not relevant Not relevant
This is a subtidal biotope so desiccation is not a relevant factor for consideration.
Not relevant Not relevant Not relevant Not relevant Not relevant
CMU.Beg is a subtidal biotope so an increase in emergence is not relevant.
Not sensitive* Not relevant
CMU.Beg is a subtidal biotope so an increase in emergence is not relevant.
High High Moderate Rise High
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).
Not sensitive* Not relevant
The biotope normally develops in areas of low water flow rate and so is likely to be relatively tolerant of a further decrease.
Tolerant Not relevant Not relevant No change Very low
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.
No information No information NR Insufficient
information
There was no information found regarding the of reduced temperature on Beggiatoa spp. directly.
Tolerant Not relevant Not relevant No change High
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.
Tolerant Not sensitive* No change High
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.
High Very high Low No change Moderate
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.
Not sensitive* Not relevant
The biotope is only found in areas where there is no wave exposure so a decrease is not relevant.
Tolerant Not relevant Not relevant No change High
The biotope is not likely to be sensitive to noise.
Tolerant Not relevant Not relevant No change High
The biotope is likely to be not sensitive to visual disturbance.
Low Immediate Not sensitive No change High
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.
Tolerant Not relevant Not relevant No change Moderate
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 Pressures

 IntoleranceRecoverabilitySensitivityRichnessEvidence/Confidence
No information Not relevant No information Insufficient
information
Not relevant
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
No information Not relevant No information Insufficient
information
Not relevant
There is no information available regarding the impact of heavy metals on Beggiatoa mats.
Hydrocarbon contamination
Tolerant Not relevant Not relevant No change High
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
Tolerant Not relevant Not relevant Not relevant Not relevant
There is no information available regarding the impact of radionuclides on Beggiatoa mats.
Changes in nutrient levels
Tolerant* Not relevant Not sensitive* No change High
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.
Low Very high Very Low No change Very low
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.
Low Very high Moderate No change Very low
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.
Tolerant* Not relevant Not sensitive* No change High
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 Pressures

 IntoleranceRecoverabilitySensitivityRichnessEvidence/Confidence
No information Not relevant No information Insufficient
information
Low
There are no known pathogens associated with Beggiatoa.
Tolerant Not relevant Not relevant Not relevant Moderate
There are no known non-native bacteria or species that compete with Beggiatoa.
Not relevant Not relevant Not relevant Not relevant High
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.
Not relevant Not relevant Not relevant Not relevant High

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.

Importance review

Policy/Legislation

Habitats of Principal ImportanceMud habitats in deep water
Habitats of Conservation ImportanceMud habitats in deep water
UK Biodiversity Action Plan PriorityMud habitats in deep water

Exploitation

There are no species of commercial interest in this biotope and so would not be subject to exploitation.

Additional information

-

Bibliography

  1. Bernhard, J.M., Buck, K.R., Farmer, M.A. & Bowser, S.S., 2000. The Santa Barbara Basin is a symbiosis oasis. Nature, 403, 77-80.
  2. Connor, D.W., Dalkin, M.J., Hill, T.O., Holt, R.H.F. & Sanderson, W.G., 1997a. Marine biotope classification for Britain and Ireland. Vol. 2. Sublittoral biotopes. Joint Nature Conservation Committee, Peterborough, JNCC Report no. 230, Version 97.06., Joint Nature Conservation Committee, Peterborough, JNCC Report no. 230, Version 97.06.
  3. Davies, I.M., Smith, P., Nickell, T.D. & Provost, P.G., 1996. Interactions of salmon farming and benthic microbiology in sea lochs. In Aquaculture and sea lochs (ed. K.D. Black), pp. 33-39., Oban: Scottish Association for Marine Science
  4. Diaz, R.J. & Rosenberg, R., 1995. Marine benthic hypoxia: a review of its ecological effects and the behavioural responses of benthic macrofauna. Oceanography and Marine Biology: an Annual Review, 33, 245-303.
  5. Findlay, R.H., 2002. Test of a model that predicts benthic impact of salmon net pen aquaculture. http://www.mar.dfo-mpo.gc.ca/science/mesd/he/eim/papers/findlay.html, 2026-04-02
  6. Graco, M., Farias, L., Molina, V., Gutierrez, D. & Nielsen, L.P. 2001. Massive developments of microbial mats following phytoplankton blooms in a naturally eutrophic bay: Implications for nitrogen cycling. Limnology and Oceanography, 46, 821-832.
  7. Gustafsson, M. & Nordberg, K., 1999. Benthic foraminifera and their response to hydrography, periodic hypoxic conditions and primary production in the Koljo fjord on the Swedish west coast. Journal of Sea Research, 41, 163-178.
  8. Hagen, K.D. & Nelson, D.C., 1997. Use of reduced sulfur compounds by Beggiatoa spp.: enzymology and physiology of marine and freshwater strains in homogeneous and gradient cultures. Applied and Environmental Microbiology, 63, 3957-3964.
  9. Hiscock, K., Southward, A., Tittley, I., Jory, A. & Hawkins, S., 2001. The impact of climate change on subtidal and intertidal benthic species in Scotland. Scottish National Heritage Research, Survey and Monitoring Report , no. 182., Edinburgh: Scottish National Heritage
  10. JNCC (Joint Nature Conservation Committee), 1999. Marine Environment Resource Mapping And Information Database (MERMAID): Marine Nature Conservation Review Survey Database. [on-line] http://www.jncc.gov.uk/mermaid,
  11. Lumb, C.M., 1989. Self-pollution by Scottish salmon farms? Marine Pollution Bulletin, 20, 375-379.
  12. Spies, R.B. & Davis, P., 1979. The infaunal benthos of a natural oil seep in the Santa Barbara Channel. Marine Biology, 50, 227-237.
  13. Williams, T.M & Unz, R.F., 1989. The nutrition of Thiothrix, Type 021N, Beggiatoa and Leucothrix strains. Water Research, 23, 15-22.

Citation

This review can be cited as:

Hill, J.M. 2002. Beggiatoa spp. on anoxic sublittoral mud. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. Available from: http://www.marlin.ac.uk/habitat/detail/181

Last Updated: 17/05/2002