The Marine Life Information Network

Substratum loss

Benchmark. All of the substratum occupied by the species or biotope under consideration is removed. A single event is assumed for sensitivity assessment. Once the activity or event has stopped (or between regular events) suitable substratum remains or is deposited. Species or community recovery assumes that the substratum within the habitat preferences of the original species or community is present. Further details

Evidence

Removal of the substratum will result in removal of the attached colonies of Bugulina turbinata. Therefore, an intolerance of high has been recorded. Recovery will probably take more than a year in most cases, and has been assessed as high (see additional information below).

Smothering

Benchmark. All of the population of a species or an area of a biotope is smothered by sediment to a depth of 5 cm above the substratum for one month. Impermeable materials, such as concrete, oil, or tar, are likely to have a greater effect. Further details.

Evidence

Smothering by 5 cm of sediment is likely to prevent feeding, and hence growth and reproduction, as well as respiration. In addition, associated sediment abrasion may remove or damage the bryozoan colonies. A layer of sediment will probably also interfere with larval settlement. Therefore, an intolerance of high has been recorded. Recoverability has been assessed as high (see additional information below).

Increase in suspended sediment

Benchmark. An arbitrary short-term, acute change in background suspended sediment concentration e.g., a change of 100 mg/l for one month. The resultant light attenuation effects are addressed under turbidity, and the effects of rapid settling out of suspended sediment are addressed under smothering. Further details

Evidence

Bryozoans are suspension feeding organisms that may be adversely affected by increases in suspended sediment, due to clogging of their feeding apparatus. Bryozoan turfs form preferentially on steep surfaces and under overhangs and larvae preferentially settle under overhangs, presumably to avoid smothering and siltation (Ryland, 1977; Hartnoll, 1983). Wendt (1998) noted that Bugula neritina grew faster on downward facing surfaces than upward facing surfaces, presumably due to siltation and reduced feeding efficiency on upward facing surfaces. However, where water flow is sufficient to prevent siltation, Bugulina turbinata may colonize upward facing surfaces (Hiscock & Mitchell, 1980). In addition, a layer of silt may prevent larval settlement and sediment scour may remove colonies. Overall, Bugulina turbinata is likely to encounter turbid conditions under boulders which may restrict its abundance in these habitats. An increase in suspended sediment at the benchmark level is likely to at least reduce the population abundance and may exclude some Bugula species, therefore, an intolerance of intermediate has been recorded. Recoverability is likely to be very high (see additional information below).

Decrease in suspended sediment

Benchmark. An arbitrary short-term, acute change in background suspended sediment concentration e.g., a change of 100 mg/l for one month. The resultant light attenuation effects are addressed under turbidity, and the effects of rapid settling out of suspended sediment are addressed under smothering. Further details

Evidence

Bryozoan turfs are often abundant in clear, fast flowing waters (Moore, 1977a). A decrease in suspended sediment is likely to increase the abundance of bryozoans, including species of Bugula. Therefore, tolerant* has been recorded.

Desiccation

1. A normally subtidal, demersal or pelagic species including intertidal migratory or under-boulder species is continuously exposed to air and sunshine for one hour.
2. A normally intertidal species or community is exposed to a change in desiccation equivalent to a change in position of one vertical biological zone on the shore, e.g., from upper eulittoral to the mid eulittoral or from sublittoral fringe to lower eulittoral for a period of one year. Further details.

Evidence

Although occurring in the intertidal, Bugulina turbinata is restricted to damp underboulder and overhang habitats. Dyrynda & Ryland (1982) noted that rapid growth in Bugulina flabellata was associated with light skeletalization. On emersion, the branching form of Bugulina turbinata probably holds some water. However, it is probably intolerant of drying and water loss. Therefore, an increase in desiccation at the benchmark level (e.g. by overturning of boulders to which the colonies are attached) is likely to result in loss of the population, including dormant holdfasts, and intolerance of high has been recorded. Recovery is likely to be very high (see additional information below).

Increase in emergence regime

Benchmark. A one hour change in the time covered or not covered by the sea for a period of one year. Further details

Evidence

An increase in emergence will increase the risk of desiccation, expose the species to increased extremes of temperature and reduce the time available for feeding, hence reducing growth and reproduction. Therefore, the upper extent and abundance of the population is likely to be reduced and an intolerance of intermediate has been recorded. Recoverability is likely to be very high.

Decrease in emergence regime

Benchmark. A one hour change in the time covered or not covered by the sea for a period of one year. Further details

Evidence

A decrease in emergence is likely to allow Bugulina turbinata to extend its range further up the shore. Therefore, tolerant* has been recorded.

Increase in water flow rate

A change of two categories in water flow rate (view glossary) for 1 year, for example, from moderately strong (1-3 knots) to very weak (negligible). Further details

Evidence

Water flow has been shown to be important for the development of bryozoan communities and the provision of suitable hard substrata for colonization (Eggleston, 1972b; Ryland, 1976). In addition, areas subject to high mass transport of water such as the Menai Strait, or tidal rapids generally support large numbers of bryozoan species. Although, active suspension feeders, their feeding currents are probably fairly localized and they are dependent on water flow to bring adequate food supplies within reach (McKinney, 1986). Okamura (1984) reported that an increase in water flow from slow flow (1-2 cm/s) to fast flow (10-12 cm/s) reduced feeding efficiency in small colonies but not in large colonies of Bugulina stolonifera. Bugulina turbinata has been recorded from strong to weak tidal streams. However, an increase in water flow from e.g. moderately strong to very strong may result in loss of a proportion of the population or displacement of more tolerant species. Populations on less stable substrata such as pebbles and cobbles will probably be lost but are probably ephemeral, short-lived populations. In addition, very strong water flow may interfere with larval settlement, transporting larvae away from the adult population, and increasing settlement time and larval mortality. Therefore, an intolerance of intermediate has been recorded. Recoverability is probably very high (see additional below).

Decrease in water flow rate

A change of two categories in water flow rate (view glossary) for 1 year, for example, from moderately strong (1-3 knots) to very weak (negligible). Further details

Evidence

Water flow has been shown to be important for the development of bryozoan communities and the provision of suitable hard substrata for colonization (Eggleston, 1972b; Ryland, 1976). In addition, areas subject to high mass transport of water such as the Menai Strait and tidal rapids generally support large numbers of bryozoan species. Although, active suspension feeders, their feeding currents are probably fairly localized and they are dependent on water flow to bring adequate food supplies within reach (McKinney, 1986). A decrease in water flow, e.g. from moderately strong to very weak will probably result in impaired growth due to a reduction in food availability, and an increased risk of siltation (see above). Therefore, an intolerance of high has been recorded with a recoverability of very high (see additional information below). However, Bugulina turbinata may occur in areas of weak tidal streams, where wave action is adequate to maintain water movement (see below).

Increase in temperature

1. A short-term, acute change in temperature; e.g., a 5°C change in the temperature range for three consecutive days. This definition includes ‘short-term’ thermal discharges.
2. A long-term, chronic change in temperature; e.g. a 2°C change in the temperature range for a year. This definition includes ‘long term’ thermal discharges.

For intertidal species or communities, the range of temperatures includes the air temperature regime for that species or community. Further details

Evidence

Although species of Bugula grow and reproduce in the summer months, day length and/or the phytoplankton bloom characteristic of temperate waters are probably more important cues than temperature (Ryland, 1967; 1970). Bugulina turbinata is a predominantly southern species in British waters (Lewis, 1964; Hayward & Ryland, 1998) but has been recorded as far north as Shetland. A long term increase in temperature may increase its abundance in northern British waters and allow the species to extend its range. As an intertidal species it is likely to be exposed to extremes of temperature when emersed, and is presumably tolerant of acute temperature changes. It occurs as far south as the Mediterranean and is, therefore, probably tolerant to increases of temperature, at the benchmark level, within British waters.

Decrease in temperature

1. A short-term, acute change in temperature; e.g., a 5°C change in the temperature range for three consecutive days. This definition includes ‘short-term’ thermal discharges.
2. A long-term, chronic change in temperature; e.g. a 2°C change in the temperature range for a year. This definition includes ‘long term’ thermal discharges.

For intertidal species or communities, the range of temperatures includes the air temperature regime for that species or community. Further details

Evidence

Bugulina turbinata is a predominantly southern species extending in range to the Mediterranean (Lewis, 1964; Hayward & Ryland, 1998). Although it has been recorded as far north as Shetland, a long term decrease in temperature may reduce its extent in British waters, probably by interfering with growth and reproduction. Similarly a decreased temperature may reduce its extent or abundance in the intertidal. Therefore, an intolerance of intermediate has been recorded. Recoverability is probably very high (see additional below)

Increase in turbidity

1. A short-term, acute change; e.g., two categories of the water clarity scale (see glossary) for one month, such as from medium to extreme turbidity.
2. A long-term, chronic change; e.g., one category of the water clarity scale (see glossary) for one year, such as from low to medium turbidity. Further details

Evidence

An increase in turbidity is likely to result in a decrease in phytoplankton and macroalgal primary production, which may reduce food available to Bugulina turbinata. Therefore, an intolerance of low has been recorded.

Decrease in turbidity

1. A short-term, acute change; e.g., two categories of the water clarity scale (see glossary) for one month, such as from medium to extreme turbidity.
2. A long-term, chronic change; e.g., one category of the water clarity scale (see glossary) for one year, such as from low to medium turbidity. Further details

Evidence

A decrease in turbidity may increase phytoplankton productivity and increase food availability for growth and reproduction. However, it is unlikely to adversely affect Bugulina turbinata and tolerant has been recorded.

Increase in wave exposure

A change of two ranks on the wave exposure scale (view glossary) e.g., from Exposed to Extremely exposed for a period of one year. Further details

Evidence

Bugula spp. produce flexible erect tufts, which are likely to move with the oscillatory flow created by wave action. Bugulina turbinata has been recorded from very wave exposed to very wave sheltered habitats. However, populations on unstable substrata such as cobbles and pebbles will probably be destroyed by increased wave action or storms. In addition, increased wave action may result in increased scour in the presence of sediments and resultant loss of colonies. Therefore, an intolerance of intermediate has been recorded. Recoverability is probably very high (see additional below).

Decrease in wave exposure

A change of two ranks on the wave exposure scale (view glossary) e.g., from Exposed to Extremely exposed for a period of one year. Further details

Evidence

A decrease in wave action is unlikely to adversely affect colonies of Bugula spp. in areas where water flow (see above) is sufficient to provide food bearing water and prevent siltation. A decrease in wave action may allow Bugula spp. to colonize more ephemeral habitats such as pebbles, cobbles and shells, Therefore, tolerant* has been recorded.

Noise

1. Underwater noise levels e.g., the regular passing of a 30-metre trawler at 100 metres or a working cutter-suction transfer dredge at 100 metres for one month during important feeding or breeding periods.
2. Atmospheric noise levels e.g., the regular passing of a Boeing 737 passenger jet 300 metres overhead for one month during important feeding or breeding periods. Further details

Evidence

The species is unlikely to be sensitive to changes in noise vibrations.

Visual presence

Benchmark. The continuous presence for one month of moving objects not naturally found in the marine environment (e.g., boats, machinery, and humans) within the visual envelope of the species or community under consideration. Further details

Evidence

The species is unlikely to be sensitive to changes in visual perception.

Abrasion & physical disturbance

Benchmark. Force equivalent to a standard scallop dredge landing on or being dragged across the organism. A single event is assumed for assessment. This factor includes mechanical interference, crushing, physical blows against, or rubbing and erosion of the organism or habitat of interest. Where trampling is relevant, the evidence and trampling intensity will be reported in the rationale. Further details.

Evidence

Physical disturbance by fishing gear has been shown to adversely affect emergent epifaunal communities. For example, emergent epifauna were indicative of scallop dredge damage on Modiolus modiolus beds (see species review), and hydroid and bryozoan matrices were reported to be greatly reduced in fished areas (Jennings & Kaiser, 1998 and references therein). Mobile gears also result in modification of the substratum, including removal of shell debris, cobbles and rocks, and the movement of boulders (Bullimore, 1985; Jennings & Kaiser, 1998).

Therefore, physical disturbance by an anchor or passing dredge (see benchmark) is likely to damage fronds and remove colonies. However, some colonies and connecting stolons are likely to survive, suggesting an intolerance of intermediate. Colonies on hard substrata are probably less vulnerable to fishing activity but would probably be damaged or partially removed. Colonies growing on rocks, cobbles and shells on coarse grounds, may be removed by the dredge (see substratum loss above) and therefore, highly intolerant. Recovery is likely to be very high (see additional information below)

Displacement

Benchmark. Removal of the organism from the substratum and displacement from its original position onto a suitable substratum. A single event is assumed for assessment. Further details

Evidence

Colonies of Bugula spp. that are displaced with their substratum, e.g. shell debris, cobbles or boulders, will probably survive if moved to a suitable habitat and not crushed in the process. However, if removed from its substratum, Bugula spp. colonies can not reattach and will probably be washed to deep water or be deposited on the strand line and die. Therefore, an intolerance of high has been recorded, with a recoverability of high (see additional information below).

Synthetic compound contamination

Sensitivity is assessed against the available evidence for the effects of contaminants on the species (or closely related species at low confidence) or community of interest. For example:

• evidence of mass mortality of a population of the species or community of interest (either short or long term) in response to a contaminant will be ranked as high sensitivity;
• evidence of reduced abundance, or extent of a population of the species or community of interest (either short or long term) in response to a contaminant will be ranked as intermediate sensitivity;
• evidence of sub-lethal effects or reduced reproductive potential of a population of the species or community of interest will be assessed as low sensitivity.

The evidence used is stated in the rationale. Where the assessment can be based on a known activity then this is stated. The tolerance to contaminants of species of interest will be included in the rationale when available; together with relevant supporting material. Further details.

Evidence

Bryozoans are common members of the fouling community, and amongst those organisms most resistant to antifouling measures, such as copper-containing anti-fouling paints (Soule & Soule, 1979; Holt et al., 1995). Bryan & Gibbs (1991) reported that there was little evidence regarding TBT toxicity in Bryozoa with the exception of the encrusting Schizoporella errata, which suffered 50% mortality when exposed for 63 days to 100ng/l TBT. Rees et al. (2001) reported that the abundance of epifauna (including bryozoans) had increased in the Crouch estuary in the five years since TBT was banned from use on small vessels. This last report suggests that bryozoans may be at least inhibited by the presence of TBT. Moran & Grant (1993) reported that settlement of marine fouling species, including Bugula neritina was significantly reduced in Port Kembla Harbour, Australia, exposed to high levels of cyanide, ammonia and phenolics. Note, however, that Bugula neritina is a warm temperate species probably only remotely related to the NE Atlantic species (P. Hayward, pers. comm.). Hoare & Hiscock (1974) suggested that polyzoa were amongst the most sensitive species to acidified halogenated effluents in Amlwch Bay, Anglesey and noted that Bugulina flabellata did not occur within the bay.
Although physiological tolerances vary between species, other Bugula sp. may have a similar intolerance. Therefore, an intolerance of high has been recorded with a low confidence. Recoverability would probably be high (see additional information below).

Heavy metal contamination

Evidence

Bryozoans are common members of the fouling community, and amongst those organisms most resistant to antifouling measures, such as copper-containing anti-fouling paints (Soule & Soule, 1979; Holt et al., 1995). Most of the information found concerning the toxicity of metals to this genus concerned Bugula neritina. Lee & Trot, (1973) reported that Bugula neritina colonized wooden panels treated with copper based antifouling paints and dominated the succession after 5-7 weeks. Bugula neritina was reported to survive but not grow exposed to ionic Cu concentrations of 0.2-0.3 ppm, while larvae died above 0.3ppm (Soule & Soule, 1979). Similarly, Ryland (1967) reported that Bugula neritina died where the surface leaching rate of Cu exceeded 10µg Cu/cm²/day, while ancestrulae may recover from prolonged Cu exposure if transferred to clean sea water. Ryland (1967) also noted that Bugula neritina was less intolerant of Hg than Cu. Copper ion concentrations greater than 2.5mg CuCl₂/l stimulated a change from positive to negative phototactic response in Bugula simplex (Ryland, 1967).
Overall, Bugula spp. are likely to be relatively tolerant of copper contamination, and may be tolerant of other heavy metals. Therefore, an intolerance of low has been recorded but with low confidence given the lack of information on Bugula turbinata.

Hydrocarbon contamination

Evidence

Soule & Soule (1979) reported that Bugula neritina was lost from breakwater rocks in the vicinity of the December 1976 Bunker C oil spill in Los Angeles Harbour, and had not recovered within a year. However, it had returned to a nearby area within 5 months (May 1977) even though the area was still affected by sheens of oil. Similarly, Mohammad (1974) reported that Bugula spp. and Membranipora spp. were excluded from settlement panels near a Kuwait oil terminal subject to minor but frequent oil spills.
Therefore, although they may tolerate some hydrocarbon pollution, it is likely that Bugula species will be adversely affected by oil spills . Hence, an intolerance of high has been recorded. Recoverability is likely to be high (see additional information below).

Radionuclide contamination

Evidence

Insufficient
information

Changes in nutrient levels

Evidence

A moderate increase in nutrient levels may increase the food available to Bugula spp., either in the form of phytoplankton or detritus. Bugula stolonifera was reported to occur in areas of the Port of Genoa harbour, heavily affected by domestic sewage pollution (Soule & Soule, 1979). Other species of Bugula may shown similar tolerance. Therefore, an intolerance of low has been recorded, albeit with very low confidence.

Increase in salinity

1. A short-term, acute change; e.g., a change of two categories from the MNCR salinity scale for one week (view glossary) such as from full to reduced.
2. A long-term, chronic change; e.g., a change of one category from the MNCR salinity scale for one year (view glossary) such as from reduced to low. Further details.

Evidence

Lynch (cited in Hyman, 1959) reported that increasing salinity hastened metamorphosis in Bugula spp. larvae, resulting in a reduced swimming time of 3-30 minutes. However, little other information was found, and Bugula spp. are unlikely to be exposed to hypersaline effluents in British waters.

Decrease in salinity

1. A short-term, acute change; e.g., a change of two categories from the MNCR salinity scale for one week (view glossary) such as from full to reduced.
2. A long-term, chronic change; e.g., a change of one category from the MNCR salinity scale for one year (view glossary) such as from reduced to low. Further details.

Evidence

Ryland (1970) stated that, with a few exceptions, the Gymnolaemata were fairly stenohaline and restricted to full salinity (ca 35 psu) and noted that reduced salinities result in an impoverished bryozoan fauna. Soule & Soule (1979) suggested that some species of Bugula may be considered euryhaline, e.g. Bugula neritina and Bugula californica occur in harbours subject to large freshwater runoff. Lynch (cited in Hyman, 1959) reported that reduced salinity delayed metamorphosis in larvae of Bugula neritina but not in Bugulina flabellata or Crisularia turrita. Bugulina turbinata populations in the intertidal, are likely to be exposed to freshwater runoff and rainfall. Therefore, based on the above evidence, Bugulina turbinata may not be adversely affected by exposure to variable salinities in the short or long term (see glossary). However, it is probably intolerant of an acute change or reduction in salinity in the short term, which may result in a reduction of the extent of the population. Therefore, an intolerance of intermediate has been recorded. Recoverability is likely to be very high (see additional information below).

Changes in oxygenation

Benchmark.  Exposure to a dissolved oxygen concentration of 2 mg/l for one week. Further details.

Evidence

No information on the tolerance of Bugula spp. to changes in oxygenation was found.

Introduction of microbial pathogens/parasites

Benchmark. Sensitivity can only be assessed relative to a known, named disease, likely to cause partial loss of a species population or community. Further details.

Evidence

No information found.

Introduction of non-native species

Sensitivity assessed against the likely effect of the introduction of alien or non-native species in Britain or Ireland. Further details.

Evidence

No information found.

Extraction of this species

Benchmark. Extraction removes 50% of the species or community from the area under consideration. Sensitivity will be assessed as 'intermediate'. The habitat remains intact or recovers rapidly. Any effects of the extraction process on the habitat itself are addressed under other factors, e.g. displacement, abrasion and physical disturbance, and substratum loss. Further details.

Evidence

Bugula turbinata is not known to be subject to specific extraction. However, many bryozoans have been recently found to contain pharmacologically active substances, e.g. bryostatin extracted from Bugula neritina may have anti-cancer properties (Hayward & Ryland, 1998). Therefore, species of Bugula may be subject to harvesting in the future.

Extraction of other species

Benchmark. A species that is a required host or prey for the species under consideration (and assuming that no alternative host exists) or a keystone species in a biotope is removed. Any effects of the extraction process on the habitat itself are addressed under other factors, e.g. displacement, abrasion and physical disturbance, and substratum loss. Further details.

Evidence

Bugulina turbinata is not known to be associated with species or habitats subject to extraction.