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information on the biology of species and the ecology of habitats found around the coasts and seas of the British Isles

Loose-lying mats of Phyllophora crispa on infralittoral muddy sediment

08-11-2016

Summary

UK and Ireland classification

UK and Ireland classification

Description

Infralittoral muddy sand and sandy mud, sometimes with some shells or pebbles, and a dense, loose-lying cover of Phyllophora crispa. This biotope occurs in very sheltered conditions such as those found in sealochs and voes. SMP.Pcri is similar to other biotopes described with dense, loose-lying algae but has been less frequently recorded, and from the few records available, appears to occur in slightly deeper infralittoral waters primarily between 10 m to 30 m and typically in fully saline waters. The seaweeds in this biotope may be epiphytised by ascidians such as Ascidiella aspera.Kelp such as Saccharina latissima and red seaweeds including Plocamium cartilagineum may be present in some areas. The scallops Pecten maximus and Aequipecten opercularis may also be found occasionally in this biotope and Trailliella / Bonnemaisonia hamifera may also be present but not at the levels found in SMP.Tra. (Information from Connor et al., 2004).

Depth range

10-20 m, 20-30 m, 5-10 m

Additional information

Little information on the biology of Phyllophora crispa was found. In addition, this biotope is unique and occurs in specific habitats, so that even less information on the ecology of the biotope was available. Therefore, the sensitivity assessments are based on the general biology of Phyllophora spp., the biotope description and expert judgement, and should be interpreted with caution.

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Further information sources

Further information sources

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Sensitivity reviewHow is sensitivity assessed?

Sensitivity characteristics of the habitat and relevant characteristic species

This biotope (SMp.KSwSS.Pcri) is defined by the abundance of Phyllophora crispa in the form of dense loose-lying mats on infralittoral muddy sand and sandy mud in very wave sheltered conditions, typical of sea lochs and voes (Connor et al., 2004). The presence of other red algae and kelp varies between records of the biotope. Mobile crabs and urchins probably roam the surrounding area and epifaunal keel worms and hydroids are probably ubiquitous on any stones and pebbles in the surrounding area. The characteristic infauna is not reported except for Cerianthus lloydii which is found in many other sedimentary habitats. The remaining epiphytic ascidians and bryozoans are, by definition, dependent on the Phyllophora mat for substratum. Therefore, the sensitivity of the biotope is probably dependent on the sensitivity of the Phyllophora mat whose loss would result in loss of the biotope as described by the habitat classification.

Resilience and recovery rates of habitat

Phyllophora crispa is a perennial species growing from a small discoid holdfast. The growth form varies depending on environmental conditions but it is usually dichotomous branching with membranous or cartilaginous flat bladed fronds up to 10-15 cm in length, sometimes with up to 5-6 proliferations (Dixon & Irvine, 1977; Bunker et al., 2012; Guiry & Guiry, 2015). Dixon & Irvine (1977) noted that regeneration occurs in Phyllophora crispa after erosion or animal grazing. Molenaar & Breeman (1994) noted that Phyllophora pseudoceranoides exhibited annual growth and die back patterns where growth is removed annually by abrasion or water action leading to breakage.

Phyllophora crispa is dioecious but the gametophyte and tetrasporophyte are isomorphic. The male gametophytes release spermatangia in September to October, and female gametophytes develop cystocarps in September to March and release carpospores in January. The tetrasporangia are recorded in August to March and tetraspores are usually released in January (Newroth, 1972; Dixon & Irvine, 1977). Newroth (1972) reported that carposporelings of Phyllophora pseudoceranoides transferred from culture into the wild grew to a height of 3 cm in two years. The spores of red algae are non-motile (Norton, 1992) and therefore entirely reliant on the hydrographic regime for dispersal. Norton (1992) reviewed dispersal by macroalgae and concluded that dispersal potential is highly variable, recruitment usually occurs on a local scale, typically within 10 m of the parent plant. Hence, it is expected that the red algal turf would normally rely on recruitment from local individuals and that recovery of populations via spore settlement, where adults are removed, would be protracted.

‘Zernov’s Phyllophora field’ in the north-western Black Sea has undergone significant degradation between 1964 and 2004 due to eutrophication, resultant algal blooms and increased turbidity (BSC, 2008; Kostylev et al., 2010). The ‘field’ is composed of several species of Phyllophora including Phyllophora crispa. The Phyllophora field has remained but the abundance of the Phyllophora, the range of Phyllophora species, their age structure, the extent of the ‘field’, and the ecosystem of fish and other algae decreased or declined. However, an increase in species richness and extent of the ’field’ was reported from 2005 to 2007, so that regeneration had begun (Kostylev et al., 2010). BSC (2008) suggest that eutrophication and its effects stabilised in the 1990s and decreased in the 2000s.

Kain (1975) examined recolonization of artificially cleared areas in a Laminaria hyperborea forest in Port Erin, Isle of Man. Cleared concrete blocks were colonized by kelps and un-specified Rhodophyceae at 0.8 m. After about 2.5 years, Laminaria hyperborea standing crop, together with an understorey of red algae (Rhodophyceae), was similar to that of virgin forest. Rhodophyceae were present throughout the succession increasing from 0.04 to 1.5 percent of the biomass within the first 4 years. Succession was similar at 4.4 m, and Laminaria hyperborea dominated within about 3 years. Blocks cleared in August 1969 at 4.4m were dominated by Rhodophyceae after 41 weeks, e.g. Delesseria sanguinea and Cryptopleura ramosa. Kain (1975) cleared one group of blocks at two monthly intervals and noted that Phaeophyceae were dominant colonists in spring, Chlorophyceae (solely Ulva lactuca) in summer and Rhodophyceae were most important in autumn and winter.  However, Phyllophora crispa was not reported in her study.

Resilience assessment. No direct evidence of recovery was found. The growth rate of Phyllophora pseudoceranoides might suggest that Phyllophora crispa would take several years to recover its full length of 10-15 cm, although it is also reported to regenerate (Newroth, 1972; Dixon & Irvine, 1977). Recovery of the extensive field of Phyllophora spp. in the Black Sea does not provide a precise timeline but again suggests several years for recovery to begin. Therefore, where a proportion of the population of Phyllophora is removed or lost (i.e. resistance in ‘Medium’) then resilience is assumed to be High. However, where a significant proportion of the Phyllophora mat is lost or removed, resilience is assumed to be Medium (2-10 yrs) but with ‘Low’ confidence based on expert judgement and little supporting evidence.

Hydrological Pressures

 ResistanceResilienceSensitivity
High High Not sensitive
Q: Low
A: NR
C: NR
Q: Low
A: NR
C: NR
Q: Low
A: Low
C: Low

Phyllophora crispa is widely distributed on the coasts of the British Isles, except in the east of England. It is widely distributed in the east Atlantic with a northern limit in Iceland and a southern limit in North Africa but is also present in the Mediterranean and Black Sea (Newroth, 1971; Dixon & Irvine, 1977; Guiry & Guiry, 2015; Bunker et al., 2012). OBIS (2016) recorded Phyllophora crispa in waters of 8.5 to 14.5°C, although the derivation of the records is unclear. Kooistra et al. (1989) noted that it was limited to lower shore tide pools but concluded that temperature and salinity were not the limiting factors but that oxygenation and completion were possible limiting factors. However, Gallon et al. (2014) reported that changes in red seaweed assemblages across Brittany were correlated with a 0.7°C increase in coastal water temperature over the prior twenty years. Species varied in their response but the occurrence of several species of red algae, including Phyllophora crispa, increased.  

Sensitivity assessment.  Phyllophora crispa is distributed to the north and south of the British Isles and, therefore, is probably tolerant of a long-term 2°C change in temperature for a year. It is also likely to tolerate a 5°C change in the short-term. Therefore, a resistance of High is suggested so that resilience is High (by default) and the biotope is assessed as Not sensitive at the benchmark level.  However, confidence in the assessed in Low as it is based on expert judgment and proxies for evidence.

High High Not sensitive
Q: Low
A: NR
C: NR
Q: Low
A: NR
C: NR
Q: Low
A: NR
C: NR

Phyllophora crispa is widely distributed on the coasts of the British Isles, except in the east of England. It is widely distributed in the east Atlantic with a northern limit in Iceland and a southern limit in North Africa but is also present in the Mediterranean and Black Sea (Newroth, 1971; Dixon & Irvine, 1977; Guiry & Guiry, 2015; Bunker et al., 2012). OBIS (2016) recorded Phyllophora crispa in waters of 8.5 to 14.5°C, although the derivation of the records is unclear. Kooistra et al. (1989) noted that it was limited to lower shore tide pools but concluded that temperature and salinity were not the limiting factors but that oxygenation and completion were possible limiting factors.

Sensitivity assessment.  Phyllophora crispa is distributed to the north and south of the British Isles and, therefore, is probably tolerant of a long-term 2°C change in temperature for a year. It is also likely to tolerate a 5°C change in the short-term. Therefore, a resistance of High is suggested so that resilience is High (by default) and the biotope is assessed as Not sensitive at the benchmark level.  However, confidence in the assessed in Low as it is based on expert judgment and proxies for evidence.

No evidence (NEv) Not relevant (NR) No evidence (NEv)
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

Phyllophora crispa is recorded from shady places in the lower littoral, lower littoral pools and subtidally to ca 30m (Dixon & Irvine, 1977; Bunker et al., 20102). Kooistra et al. (1989) noted that Phyllophora crispa was limited to lower shore tide pools but concluded that temperature and salinity were not the limiting factors but that oxygenation and competition were possible limiting factors.  Maximova (2013; summary only) reported that ‘morphological and biological changes’ in Phyllophora crispa from the Black Sea changed in experiments where the ‘normal’ salinity was raised from 18 ppt to 25, 32 and 39, but no further details were available.  OBIS (2016) recorded Phyllophora crispa in waters of 17.9 to 38 pps, although the derivation of the records is unclear.

Sensitivity assessment.  The presence of Phyllophora crispa in the lower intertidal suggests that it might be exposed to changes in salinity due to evaporation or rainfall but only for very short periods.  This biotope (KSwSS.Pcri) is only recorded from full salinity so that an increase in salinity at the benchmark level would expose the biotope to hypersaline conditions, for example from hypersaline effluents.  However, no evidence on which to base and assessment was found.

Medium High Low
Q: Low
A: NR
C: NR
Q: Low
A: NR
C: NR
Q: Low
A: Low
C: Low

Phyllophora crispa is recorded from shady places in the lower littoral, lower littoral pools and subtidally to ca 30m (Dixon & Irvine, 1977; Bunker et al., 20102). Kooistra et al. (1989) noted that Phyllophora crispa was limited to lower shore tide pools but concluded that temperature and salinity were not the limiting factors but that oxygenation and competition were possible limiting factors.  Maximova (2013; summary only) reported that ‘morphological and biological changes’ in Phyllophora crispa from the Black Sea changed in experiments where the ‘normal’ salinity was raised from 18 ppt to 25, 32 and 39, but no further details were available.  OBIS (2016) recorded Phyllophora crispa in waters of 17.9 to 38 pps, although the derivation of the records is unclear. A comparative study of salinity tolerances of macroalgae collected from North Zealand and the South Kattegat (Denmark) where salinity is 16 psu showed that species generally had a high tolerance (maintained more than half of photosynthetic capacity in short-term exposures of 4 days) to salinities lower than 3.7 psu. However, tolerances varied between species with Phyllophora pseudoceranoides exhibiting greater tolerance than Phycodrys rubens, which was the least resistant species tested (Larsen & Sand-Jensen, 2006).

Sensitivity assessment.  The presence of Phyllophora crispa in the lower intertidal suggests that it might be exposed to changes in salinity due to evaporation or rainfall but only for very short periods. This biotope (KSwSS.Pcri) is only recorded from full salinity so that a decrease in salinity at the benchmark level would expose the biotope to reduced salinity conditions (18-30 psu). The observations from the Black Sea, the South Kattegat and OBIS suggest that Phyllophora crispa could survive reduced salinity conditions but the biotope would probably experience a reduction in species richness and less resistant species left or were lost from the biotope. Therefore, a resistance of Medium is suggested. Resilience is probably High so that sensitivity is assessed as Low at the benchmark level. However, confidence in the assessed in Low as it is based on expert judgment and proxies for evidence.

Low Medium Medium
Q: Low
A: NR
C: NR
Q: Low
A: NR
C: NR
Q: Low
A: Low
C: Low

Phyllophora crispa was recorded from moderately strong to very weak tidal flow (Connor et al., 2004). It has been recorded to regenerate after erosion (Dixon & Irvine, 1977) while Molenaar & Breeman (1994) noted that Phyllophora pseudoceranoides exhibited annual growth and die back patterns where growth was removed annually by abrasion or water action.  However, this biotope is unusual because the very weak to weak tidal streams and very wave sheltered conditions allow Phyllophora crispa to grow abundantly on fine sediments (muddy sands and sandy muds).  It is presumably attached to small stones  within the sediment.  A significant increase in water flow may winnow away the mud surface or even remove the mud habitat and hence the biotope if prolonged. An increase of 0.2 m/s may begin to erode the mud surface where the site is already subject to flow (e.g. weak flow at the seabed), based on sediment erosion deposition curves (Wright, 2001). Therefore, an increase in water flow could result in the loss of the ‘loose-lying’ mat of Phyllophora crispa.  However, an increase of only 0.1-0.2 m/s may only affect example of the biotope already in weak flow, rather than very weak flow and a resistance of Low is suggested with Low confidence. Resilience is probably Medium so that sensitivity is assessed as Medium.

Not relevant (NR) Not relevant (NR) Not relevant (NR)
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

Changes in emergence are ‘Not relevant’ to this biotope, which is restricted to fully subtidal habitats. The pressure benchmark is relevant only to littoral and shallow sublittoral fringe biotopes.

High High Not sensitive
Q: Low
A: NR
C: NR
Q: High
A: High
C: High
Q: Low
A: Low
C: Low

Phyllophora crispa was recorded from wave exposed to very wave sheltered sites (Connor et al., 2004). It has been recorded to regenerate after erosion (Dixon & Irvine, 1977) while Molenaar & Breeman (1994) noted that Phyllophora pseudoceranoides exhibited annual growth and die back patterns where growth was removed annually by abrasion or water action.  However, this biotope is unusual because the very weak to weak tidal streams and very wave sheltered conditions allow Phyllophora crispa to grow abundantly on fine sediments (muddy sands and sandy muds).  It is presumably attached to small stones within the sediment.  A further decrease in wave exposure is unlikely to affect the biotope. However, an increase in wave exposure is likely to remove the loose-lying mat of Phyllophora crispa but a 3-5% change in significant wave height (the benchmark) is unlikely to have a significant effect. Therefore, the biotope is probably Not sensitive (resistance and resilience are High) at the benchmark level. 

Chemical Pressures

 ResistanceResilienceSensitivity
Not relevant (NR) Not relevant (NR) Not sensitive
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

This biotope is considered to be 'Not sensitive' at the pressure benchmark that assumes compliance with all relevant environmental protection standards.

Not relevant (NR) Not relevant (NR) Not sensitive
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

This biotope is considered to be 'Not sensitive' at the pressure benchmark that assumes compliance with all relevant environmental protection standards.

Not relevant (NR) Not relevant (NR) Not sensitive
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

This biotope is considered to be 'Not sensitive' at the pressure benchmark that assumes compliance with all relevant environmental protection standards.

No evidence (NEv) Not relevant (NR) No evidence (NEv)
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

No evidence was found

Not relevant (NR) Not relevant (NR) Not sensitive
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

This biotope is considered to be 'Not sensitive' at the pressure benchmark that assumes compliance with all relevant environmental protection standards.

No evidence (NEv) Not relevant (NR) No evidence (NEv)
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

Kooistra et al. (1989) noted that Phyllophora crispa was limited to lower shore tide pools but concluded that temperature and salinity were not the limiting factors but that oxygenation and competition were possible limiting factors.  However, no direct evidence was found.

Not relevant (NR) Not relevant (NR) Not sensitive
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

‘Zernov’s Phyllophora field’ in the north-western Black Sea has undergone significant degradation between 1964 and 2004 due to eutrophication, resultant algal blooms and increased turbidity (BSC, 2008; Kostylev et al., 2010). The ‘field’ is composed of several species of Phyllophora including Phyllophora crispa. The Phyllophora field has remained but the abundance of the Phyllophora, the range of Phyllophora species, their age structure, the extent of the ‘field’, and the ecosystem of fish and other algae decreased or declined. Although the Black Sea is a unique environment, the results suggest that nutrient enrichment could affect the biotope and its associated community adversely.  Nevertheless, this biotope is considered to be 'Not sensitive' at the pressure benchmark that assumes compliance with good status as defined by the WFD.

No evidence (NEv) Not relevant (NR) No evidence (NEv)
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

‘Zernov’s Phyllophora field’ in the north-western Black Sea has undergone significant degradation between 1964 and 2004 due to eutrophication, resultant algal blooms and increased turbidity (BSC, 2008; Kostylev et al., 2010). The ‘field’ is composed of several species of Phyllophora including Phyllophora crispa. The Phyllophora field has remained but the abundance of the Phyllophora, the range of Phyllophora species, their age structure, the extent of the ‘field’, and the ecosystem of fish and other algae decreased or declined.  It is unclear if the eutrophication in the Black Sea resulted from nutrients, organic loading, or both. Therefore, in the absence of clear evidence no assessment has been made.

Physical Pressures

 ResistanceResilienceSensitivity
None Very Low High
Q: High
A: High
C: High
Q: High
A: High
C: High
Q: High
A: High
C: High

All marine habitats and benthic species are considered to have a resistance of ‘None’ to this pressure and to be unable to recover from a permanent loss of habitat (resilience is ‘Very Low’).  Sensitivity within the direct spatial footprint of this pressure is, therefore ‘High’.  Although no specific evidence is described confidence in this assessment is ‘High’, due to the incontrovertible nature of this pressure.

None Very Low High
Q: High
A: High
C: High
Q: High
A: High
C: High
Q: High
A: High
C: High

If sedimentary substrata were replaced with rock substrata the biotope would be lost, as it would not longer be a sedimentary habitat.

Sensitivity assessment. Resistance to the pressure is considered ’None‘, and resilience ’Very low‘ or ‘None’ (as the pressure represents a permanent change) and the sensitivity of this biotope is assessed as ’High’.

High High Not sensitive
Q: Low
A: NR
C: NR
Q: High
A: High
C: High
Q: Low
A: Low
C: Low

This biotope is recorded from sandy gravelly muds (Connor et al., 2004, sediment matrix). Phyllophora crispa is found on other substrata, including rock and other seaweeds. The low energy environment of the biotope, i.e. low water flow and wave sheltered conditions, determines the nature of the sediment. The muddy sediment is probably inhospitable to most other macroalgae so that Phyllophora can become abundant. A change in sediment from sand muddy gravels to gravel or mud may not affect the biotope adversely. Bunker et al. (2012) note that Phyllophora crispa thrives on rock subject to shell gravel. Therefore, in the very sheltered condition so of this biotope, the mat of Phyllophora would probably survive on gravel or on muds where enough stone for attachment remains. Therefore, the biotope is probably Not sensitive (resistance and resilience are High) at the benchmark level. 

None Medium Medium
Q: Low
A: NR
C: NR
Q: Low
A: NR
C: NR
Q: Low
A: Low
C: Low

The biotope is an epifloral mat sitting on the surface of the sediment. Extraction of the sediment to any depth would result in removal of the Phyllophora mat from the affected area.  Therefore, a resistance of None is suggested. Resilience is probably Medium and sensitivity is assessed as Medium but with Low confidence due to the lack of any direct evidence.

Low Medium Medium
Q: Low
A: NR
C: NR
Q: Low
A: NR
C: NR
Q: Low
A: Low
C: Low

Dixon & Irvine (1977) noted that Phyllophora crispa regenerates after erosion and animal grazing. Bunker et al. (2012) noted that it tolerated sediment cover and thrived in areas subject to shell gravel.  Both observations suggest that it can either resist or regrow from damage due to sediment scour or animal grazing.  However, this biotope (KSwSS.Pcri) is an epifloral mat sitting on the surface of sediment; probably loosely attaché to small stones or shells in the sediment.  Any passing bottom gear is liable to remove the mat of Phyllophora. Therefore, a resistance of Low is suggested. Resilience is probably Medium so that the sensitivity is assessed as Medium at the benchmark level but with Low confidence due to the lack of any direct evidence.

Low Medium Medium
Q: Low
A: NR
C: NR
Q: Low
A: NR
C: NR
Q: Low
A: NR
C: NR

Dixon & Irvine (1977) noted that Phyllophora crispa regenerates after erosion and animal grazing. Bunker et al. (2012) noted that it tolerated sediment cover and thrived in areas subject to shell gravel.  Both observations suggest that it can either resist or regrow from damage due to sediment scour or animal grazing.  However, this biotope (KSwSS.Pcri) is an epifloral mat sitting on the surface of sediment; probably loosely attaché to small stones or shells in the sediment.  Any passing bottom gear is liable to remove the mat of Phyllophora. Therefore, a resistance of Low is suggested. Resilience is probably Medium so that the sensitivity is assessed as Medium at the benchmark level but with Low confidence due to the lack of any direct evidence.

Low Medium Medium
Q: High
A: Medium
C: Medium
Q: Low
A: NR
C: NR
Q: Low
A: Low
C: Low

Red algae are shade tolerant macroalgae. Phyllophora crispa is particularly shade tolerant and is recorded a greater depths than many other red algae. For example, Smith & Jones (1970) reported that Phyllophora crispa grew at a greater depth (25 m) than other red algae examined on the west coast of Anglesey and Norton (1968) reported it at 33 m at St Mary’s Isles of Scilly. Norton et al. (1971) noted that Phyllophora crispa penetrated up to 15 m in a sea cave (Bullock Island Cave, near Lough Ine), although its growth was stunted at its limit into the cave. The degradation of ‘Zernov’s Phyllophora field’ in the north-western Black Sea was attributed to eutrophication, algal blooms and turbidity. All three species of Phyllophora present survived but their biomass was reduced by an order to magnitude (Kostylev et al., 2010).  Therefore, it is likely that an increase in turbidity due to suspended solids could result in a loss of a proportion of the population of Phyllophora crispa, especially in the deeper examples of the biotope and a resistance of Low is suggested. Resilience is probably Medium so that sensitivity is assessed as Medium.

High High Not sensitive
Q: Low
A: NR
C: NR
Q: High
A: High
C: High
Q: Low
A: Low
C: Low

Airoldi (2003) identified a number of morphological, physiological and life history traits that conferred high levels of tolerance to sedimentation. For example, regeneration of upright fronds from a perennial basal crust resistant to burial and scour, calcified thalli, apical meristems, large reproductive outputs, lateral vegetative growth and slow growth rates (Airoldi, 2003). Algae with tough thalli are more resistant to sedimentation and scour (Pedersén & Snoeijs, 2001). Phyllophora crispa was reported to regenerate after erosion and animal grazing (Dixon & Irvine, 1977) and Bunker et al. (2012) noted that it tolerated sediment cover and thrived in areas subject to shell gravel.  Both observations suggest that it can either resist or regrow from damage due to sediment scour.  However, in the wave sheltered, low energy conditions that typify this biotope any deposit of sediment is likely to remain and smother the biotope. 

Sensitivity assessment. Phyllophora crispa grows up to 15 cm in length, and could probably either protrude through 5 cm of deposited sediment or grow up through it.  Therefore, a resistance of High is suggested. Resilience is, therefore, High and the biotope is probably Not sensitive at the benchmark level.

None Medium Medium
Q: Low
A: NR
C: NR
Q: Low
A: NR
C: NR
Q: Low
A: Low
C: Low

Airoldi (2003) identified a number of morphological, physiological and life history traits that conferred high levels of tolerance to sedimentation. For example, regeneration of upright fronds from a perennial basal crust resistant to burial and scour, calcified thalli, apical meristems, large reproductive outputs, lateral vegetative growth and slow growth rates (Airoldi, 2003). Algae with tough thalli are more resistant to sedimentation and scour (Pedersén & Snoeijs, 2001). Phyllophora crispa was reported to regenerate after erosion and animal grazing (Dixon & Irvine, 1977) and Bunker et al. (2012) noted that it tolerated sediment cover and thrived in areas subject to shell gravel.  Both observations suggest that it can either resist or regrow from damage due to sediment scour.  However, in the wave sheltered, low energy conditions that typify this biotope any deposit of sediment is likely to remain and smother the biotope. 

Sensitivity assessment. Phyllophora crispa grows up to 15 cm in length and would be completely smothered by 30 cm of deposited sediment.  The sediment is likely to remain, and the plants will be removed from light and probably succumb to localise anoxia under the sediment. Therefore, a resistance of None is suggested. Resilience is probably Medium and the sensitivity is assessed as Medium benchmark level.

Not Assessed (NA) Not assessed (NA) Not assessed (NA)
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

No evidence was found

No evidence (NEv) Not relevant (NR) No evidence (NEv)
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

No evidence was found

Not relevant (NR) Not relevant (NR) Not relevant (NR)
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

Not relevant

Medium High Low
Q: Medium
A: Medium
C: Medium
Q: Low
A: NR
C: NR
Q: Low
A: NR
C: NR

Red algae are shade tolerant macroalgae. Phyllophora crispa is particularly shade tolerant and is recorded a greater depths than many other red algae. For example, Smith & Jones (1970) reported that Phyllophora crispa grew at a greater depth (25 m) than other red algae examined on the west coast of Anglesey and Norton (1968) reported it at 33 m at St Mary’s Isles of Scilly. Norton et al. (1971) noted that Phyllophora crispa penetrated up to 15 m in a sea cave (Bullock Island Cave, near Lough Ine), although its growth was stunted at its limit into the cave. The degradation of ‘Zernov’s Phyllophora field’ in the north western Black Sea was attributed to eutrophication, algal blooms and turbidity. All three species of Phyllophora present survived but their biomass was reduced by an order to magnitude (Kostylev et al., 2010).  Therefore, shading by an artificial structure may reduce photosynthesis (depending on intensity and duration), and may reduce the abundance of algae, although Phyllophora will probably survive.  Therefore, a resistance of Medium is suggested, with a resilience of High and a sensitivity of Low. However, permanent shading may reduce the depth to which the biotope can grow, resulting in loss of deeper example of the biotope.  The biotope occurs below 5 m so that artificial lighting is unlikely to penetrate the water column enough to affect photosynthesis.

Not relevant (NR) Not relevant (NR) Not relevant (NR)
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

Not relevant

Not relevant (NR) Not relevant (NR) Not relevant (NR)
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

The pressure definition is not directly applicable to seabed biotopes so Not relevant has been recorded.  Collision via ship groundings or terrestrial vehicles is possible but the effects are probably similar to those of abrasion above.

Not relevant (NR) Not relevant (NR) Not relevant (NR)
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

Not relevant

Biological Pressures

 ResistanceResilienceSensitivity
No evidence (NEv) Not relevant (NR) No evidence (NEv)
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

No evidence was found of the translocation, breeding or species hybridization of the important characterizing species.

Medium High Low
Q: Low
A: NR
C: NR
Q: Low
A: NR
C: NR
Q: Low
A: Low
C: Low

Bonnemaisonia hamifera (and the Trailliella-phase) is a non-native species introduced to the British Isles from Japan and first recorded in 1890 (Dixon & Irvine, 1977; Maggs & Stegenga, 1998; Gollasch, 2006).  It is thought to have been introduced by shipping or with shellfish and to have dispersed by drifting on water currents (Gollasch, 2006).  Bonnemaisonia hamifera (and the Trailliella-phase) has spread around the British Isles and Europe, into the Mediterranean and the Canary Isles and north to the Orkneys and the Norwegian coast (Lüning, 1990, Maggs & Stegenga, 1998; Gollasch, 2006).  It grows rapidly, reproduces vegetatively, and can spread by fragmentation and drifting (Maggs & Stegenga, 1998).

Bonnemaisonia hamifera (and the Trailliella-phase) occurs in this biotope with Phyllophora crispa but at a lower abundance than its characteristic biotope (KSwSS.Tra). KSwSS.Tra occurs in shallower waters but otherwise similar conditions. Therefore, if the abundance of Phyllophora crispa was reduced by an external factor then the Trailliella might be about to take over the available space, especially in the shallow examples of the biotope (KSwSS.Pcri). However, there is no evidence that this has happened to date.  Therefore, a precautionary resistance of Medium is suggested but with a ‘Low’ confidence. Resilience is probably High so that sensitivity is assessed as Low.

No evidence (NEv) Not relevant (NR) No evidence (NEv)
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

No evidence was found.

Not relevant (NR) Not relevant (NR) Not relevant (NR)
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR
Q: NR
A: NR
C: NR

Phyllophora crispa is unlikely to be targetted by any commercial or recreational fishery or harvest.

None Medium Medium
Q: Low
A: NR
C: NR
Q: Low
A: NR
C: NR
Q: Low
A: Low
C: Low

Accidental physical disturbance due to access (e.g. trampling), grounding, or passing fishing gear is examined under abrasion above. However, the accidental removal of the Phyllophora mat would result in a significant change in the biological character of, and loss of, the biotope. Therefore, a resistance of None is suggested. Resilience is probably Medium so that sensitivity is assessed as Medium but with 'Low' confidence.

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Citation

This review can be cited as:

Tyler-Walters, H., 2016. Loose-lying mats of [Phyllophora crispa] on infralittoral muddy sediment. 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/187

Last Updated: 22/06/2016