Please quote as: Lancaster, J. (Ed.), McCallum, S., Lowe A.C., Taylor, E., Chapman A. & Pomfret, J. (2014).
Development of detailed ecological guidance to support the application of the Scottish MPA selection guidelines in
Scotland’s seas. Scottish Natural Heritage Commissioned Report No.491. Deep Sponge Communities –
supplementary document.
Deep Sponge Communities
Component of MPA search feature: Northern sea fan and sponge communities
Biotope:
CR.HCR.DpSp
Deep sponge communities (circalittoral)
Sub-biotope: CR.HCR.DpSp.PhaAxi
Phakellia ventilabrum and axinellid sponges on deep, wave-exposed
circalittoral rock
Territorial/Offshore waters: Both
Sponges are important structural components of sessile communities; they contribute
to bioerosion, consolidate sediment and stabilise habitats thereby reducing physical
disturbance, and through aggressive competitive growth and seasonal retraction
maintain space for new recruits and species thus maintaining biodiversity (Bell,
2008). Sponges provide living space for small epifauna within their oscula and canal
system (Konnecker, 2002), as well as shelter for large mobile predators such as fish
and crustaceans. Upright sponges act as baffles on water currents near the sea bed,
influencing the food intake of suspension feeders and also creating an elevated
platform for epifauna to settle on (e.g. brittlestars) thereby allowing an increased food
supply to filter feeders (Konnecker, 2002). These communities are uncommon in UK
territorial waters with the majority of records from Scotland. It is likely that underrecording of these communities has occurred due to its proclivity for deep water
habitats, thus preventing in situ identification by divers.
Functional Links
Functional links and associations with Priority Marine Features
Several priority features are found within and adjacent to the deep sponge
communities, some of these may be present as a direct result of a functional link
(either biotic or abiotic). Although in most cases the functional link can only be
speculated upon, their close association with a number of species and habitats
suggests that an important ecosystem function is carried out.

Pink sea fingers: The hard rock substratum within deep sponge communities
provides a source of attachment for the octocoral Alcyonium hibernicum (pink
sea fingers). The functional significance of this association is not known.

White cluster anemone; European spiny lobster: Predatory species
associated with deep sponge communities, such as the white cluster
anemone (Parazoanthus anguicomus) and European spiny lobster (Palinurus
elephas), will remove a number of organisms through predator-prey
interactions and may also create additional living space by this process. The
rock substratum within these communities provides a source of attachment
for the white cluster anemone.

Northern feather star: The northern feather star (Leptometra celtica) has
been found in the sub-biotope CR.HCR.DpSp.PhaAxi1 (Roberts et al., 2005);
however, it is unknown how this animal contributes towards the functioning of
the ecosystem other than filter-feeding on plankton.

Northern sea fan and sponge communities: The northern sea fan (Swiftia
pallida) can be commonly found among the deep sponge community; with the
hard rock substratum providing a source of attachment. Subtle changes in the
environment may give rise to a greater abundance of sea fans and cup corals
(Caryophyllia smithii) resulting in a transition from the .DpSp biotope to the
CR.HCR.XFa.SwiLgAs2 biotope. It is not known if these habitats have a
functional link although they can occur in close proximity to one another.

Cold-water coral reefs: The coral reef framework produced by Lophelia
pertusa, and to a lesser extent Madrepora oculata, provides a hard
substratum allowing colonisation by sponges. Sponges play an important role
in reef dynamics as they are one of the primary bioeroders of coralline
structures (Beuck et al., 2007). They are also able to bind coral structures;
Wulff (2001) mentions how this capability enhances coral survival and
mediates regeneration of physically damaged reefs. Though Wulff (2001)
carried out the work on tropical corals it is also considered relevant to
temperate reefs (Bell, 2008). Modification of the coral structures increase
habitat complexity and help maintain biodiversity.
Functional links with the wider Scottish marine ecosystem
Sponge communities enhance the biodiversity of an area by increasing habitat
heterogeneity and complexity. In addition, work by Wulff (2001) Diaz and Rützler
(2001) and a review by Bell (2008) highlight a number of other important functions
carried out by deep sponge communities relevant to the wider marine environment
including: stabilisation of the substratum, carbon cycling (i.e. by suspension feeding
on planktonic organisms), silicon cycling (Maldonado et al., 2005), creating structures
that mobile animals can use to shelter from currents and predators (Auster et al.,
1997, in Bradshaw et al., 2003) and provision of a food resource. The larvae of many
species found in deep sponge communities also make a considerable contribution
towards local plankton populations (Hartnoll, 1998).
1
Phakellia ventilabrum and Axinellid sponges on deep, wave- exposed circalittoral rock
Mixed turf of hydroids and large ascidians with Swiftia pallida and Caryophyllia smithii on
weakly tide-swept circalittoral rock
2
2
Biological Diversity
Habitat/Biotope description for Scottish waters
There is one biotope and one sub-biotope described for deep sponge communities
that occur in Scotland. Discrimination of deep sponge communities is often difficult
owing to the reliance on ROV or drop-down video footage, as the depth commonly
precludes diver analysis. Furthermore, there are no discrete criteria for differentiation
of the sub-biotope from CR.HCR.DpSp in the JNCC biotope classification (Connor et
al., 2004); though it is generally accepted that large numbers of Phakellia and
axinellid sponges are an identifying feature of the CR.HCR.DpSp.PhaAxi biotope,
thus making identification highly subjective.
The following habitat description is taken directly from JNCC’s Marine Habitat
Classification Hierarchy (Connor et al., 2004) (see boxed text), with supplementary
information from other sources, below each box
Deep sponge communities (circalittoral) (CR.HCR.DpSp)
“This biotope complex typically occurs on deep (commonly below 30m depth), waveexposed circalittoral rock subject to negligible tidal streams. The sponge component
of this biotope is the most striking feature, with similar species to the bryozoan and
erect sponge biotope complex, although in this case, the sponges Phakellia
ventilabrum, Axinella infundibuliformis, Axinella dissimilis and Stelligera stuposa
dominate. Other sponge species frequently found on exposed rocky coasts are also
present in low to moderate abundance. These include Cliona celata, Polymastia
boletiformis, Haliclona viscosa, Pachymatisma johnstonia, Dysidea fragilis, Suberites
carnosus, Stelligera rigida, Hemimycale columella and Tethya aurantium. The cup
coral Caryophyllia smithii and the anemone Corynactis viridis may be locally
abundant in some areas, along with the holothurian Holothuria forskali. The soft
corals Alcyonium digitatum and Alcyonium glomeratum are frequently observed. The
bryozoans Pentapora foliacea and Porella compressa are also more frequently found
in this deep-water biotope complex. Bryozoan crusts such as Parasmittina trispinosa
are also occasionally recorded. Isolated clumps of large hydroids such as
Nemertesia antennina, Nemertesia ramosa and Sertularella gayi may be seen on the
tops of boulders and rocky outcrops. Large echinoderms such as Echinus
esculentus, Luidia ciliaris, Marthasterias glacialis, Stichastrella rosea, Henricia
oculata and Aslia lefevrei may also be present. The top shell Calliostoma zizyphinum
is often recorded as present” (Connor et al., 2004)
Additional sources of information describe a species rich hydroid/bryozoan turf which
may develop in the understorey of this diverse sponge assemblage, typically
consisting of hydroids such as Aglaophenia pluma, erect bryozoans including Cellaria
sinuosa, Bugula flabellata, Bugula plumose, Bugula turbinata, P. foliacea, A.
diaphanum and colonial ascidians such as C. lepadiformis (Fish & Fish, 1996).
Sponge fields also support various ophiuroids, which use the sponges as elevated
perches (OSPAR, 2008), and in Scottish waters are likely to be associated with the
northern sea fan S. pallida (Hiscock & Jones, 2004).
3
Phakellia ventilabrum and axinellid sponges
circalittoral rock (CR.HCR.DpSp.PhaAxi)
on
deep,
wave-exposed
“This biotope typically occurs on the upper faces of deep (commonly below 30m
depth), wave-exposed circalittoral rock subject to negligible tidal streams. Although it
occurs in exposed and very exposed conditions, at such depth, the turbulent wave
action appears to have a much-attenuated effect on the fauna compared with
shallower depths. As the majority of records are from depths between 30-50+ m,
slightly deeper than the depths of most surveys, it is possible that this biotope is
more widespread than the available dataset indicates. The sponge component of this
biotope is the most striking feature, with similar species to the bryozoan and erect
sponge biotope complex, although in this case, the sponges P. ventilabrum, A.
infundibuliformis, A. dissimilis and S. stuposa dominate. Other sponge species
frequently found on exposed rocky coasts are also present in low to moderate
abundance. These include C. celata, P. boletiformis, H. viscosa, P. johnstonia, D.
fragilis, Suberites carnosus, Stelligera rigida, H. columella and T. aurantium. The cup
coral Caryophyllia smithii and the anemone C. viridis may be locally abundant in
some areas, along with the holothurian H. forskali. The soft corals A. digitatum and A.
glomeratum are frequently observed. The bryozoans P. foliacea and P. compressa
are also more frequently found in this deep-water biotope. Bryozoan crusts such as
P. trispinosa are also occasionally recorded. Isolated clumps of large hydroids such
as N. antennina, N. ramosa and S. gayi may be seen on the tops of boulders and
rocky outcrops. Large echinoderms such as E. esculentus, L. ciliaris, M. glacialis, St.
rosea, H. oculata and A. lefevrei may also be present. The top shell C. zizyphinum is
often recorded as present” (Connor et al., 2004).
Off the Isle of Seil, Firth of Lorn (see Howson et al., 2006) this biotope was recorded
at a depth of 40m and contained cup corals, ascidians, brittlestars and feather stars.
Roberts et al. (2005) found the Lophelia pertusa coral reef communities alongside
this biotope off Mingulay in the Outer Hebrides.
Species diversity
No information currently available.
Key and characterising species
These have been taken from JNCC’s biotope descriptions (Connor et al., 2004)
Biotope type
CR.HCR.DpSp
Key species for identification
The sponges P. ventilabrum, A.
infundibuliformis, A. dissimilis
and S. stuposa dominate
CR.HCR.DpSp.PhaAxi
The
sponges
ventilabrum,
infundibuliformis,
dissimilis.
Phakellia
Axinella
Axinella
4
Additional characterising species
P. johnstonia, T. aurantium, P. boletiformis,
Suberites carnosus, S. rigida, C. celata, H.
columella, H. viscosa, D. fragilis, S. gayi, N.
antennina, N. ramosa, A. digitatum, A.
glomeratum, E. verrucosa, C. viridis, C. smithii,
C. zizyphinum, P. compressa, P. foliacea, P.
trispinosa, L. ciliaris, H. oculata, S. rosea, M.
glacialis, Echinus esculentus, H. forskali, A.
lefevrei.
P. johnstonia; T. aurantium; P. boletiformis; S.
carnosus; S. rigida; S. stuposa; C. celata; H.
columella; H. viscosa; D. fragilis; S. gayi; N.
antennina; N. ramosa; A. digitatum; A.
glomeratum; E. verrucosa; C. viridis; C. smithii;
C. zizyphinum; P. compressa; P. foliacea; P.
trispinosa; L. ciliaris; H. oculata; S. rosea; M.
glacialis; E. esculentus; H. forskali; A. lefevrei
Coherence
Typicalness
The JNCC website describes the biotope .HCR.DpSp as typically occurring in depths
greater than 30m and gives a depth band limit of 50m. However, records from around
the Scottish coast have revealed that there are a number of areas where this biotope
extends well beyond this maximal depth band. Unfortunately the limitations
associated with surveying at these depths, specifically by diver, means it is likely that
this biotope has been under recorded and is more widely distributed than current
records suggest (Connor et al., 2004).
Deep sponge communities are found on bedrock areas that are close to, but locally
sheltered from, tide-swept areas but are relatively exposed to wave action. These
conditions can be found at the entrances to some sea lochs on the west coast of
Scotland and off the Shetland and Hebridean coasts. Despite the biotopes
.HCR.DpSp and .HCR.DpSp.PhaAxi generally being thought to occur in areas of
weak tidal streams, recent records indicate that they can also be found in areas of
strong currents, for example the Firth of Lorn (Howson et al., 2006). In this region
.HCR.DpSp was recorded at a depth of 120m by ROV and indicates that, where
conditions allow, it may be found considerably deeper than 50m (Connor et al.,
2004).
A good supply of particulate material means these habitats contain many filter and
suspension feeding organisms, although the actual species present are likely to vary
depending on the geographical location and specific environmental conditions.
According to the biotope description deep sponge communities are found in areas of
high wave energy, however, the presence of sea fans and branching sponges
indicate a fairly sheltered environment (due to depth). Branching sponges of the
genus Axinella are particularly characteristic and other sponge species typical of
subtidal rocky habitats may also be present. The sea fan S. pallida and other
anthozoans such as A. digitatum and C. smithii are also commonly found. A speciesrich understorey may develop, typically consisting of hydroids, erect bryozoans and
colonial ascidians (Fish & Fish, 1996). The prominent mobile species of the
associated community consist mainly of decapod crustaceans, gastropod molluscs
and echinoderms. Fish species may also be present, but these groups are not
considered characteristic members of the community. A diverse “cryptofauna” of
nemerteans, polychaetes and amphipods also exists, living within and between the
larger sessile organisms, acting as grazers, predators and detritivores (Hartnoll,
1998). In deep sponge communities biotic disturbance is much more important than
physical disturbance in regulating diversity, with predators such as echinoderms and
crustaceans playing an important role.
Ecological variation across Scottish waters
Deep sponge communities are limited to particular areas where hydrographic
conditions are favourable, as they require a constant supply of current-borne organic
particles (Klitgaard et al., 1997; Konnecker, 2002). Until recently there were no
records of these communities in Scottish waters (see Geographical Variation for
further information). As such there is scant information on how deep sponge
communities may vary around Scotland. Its minimum depth (~30m) generally
precludes habitation by algae; however, a study by Howson et al. (2006) recorded
5
the presence of crustose red algae at ~35m in the .PhaAxi sub-biotope within the
Firth of Lorn. Although uncommon it would seem that this sub-biotope may
occasionally contain flora thus adding to the overall biodiversity. In recent years the
cold-water coral Lophelia pertusa has been recorded in .PhaAxi communities,
Roberts et al. (2005) mention the Phakellia and Axinella sponges as a major habitat
class on Lophelia rubble off the coast of Mingulay. They also note mixed populations
of the crinoids Leptometra celtica and Antedon bifida, squat lobsters and large
numbers of zoanthids alongside Phakellia sp. and Axinella sp. on a bedrock and
boulder substratum. The northern feather star (Leptometra celtica) typically occurs on
soft sediment and has not been recorded within this sub-biotope (.PhaAxi)
elsewhere.
Howson et al. (2006) record the biotope .HCR.DpSp at a depth of 120m in
Corryvreckan, Firth of Lorn. They characterise the biotope by the sponges Myxilla
sp. and Pachymatisma johnstonia along with the tunicate Ascidia mentula and
hydroid Sertularia argentea. Aside from Pachymatisma none of these species are
listed as characterising in the JNCC biotope description. The possible range of
depths within which this biotope may occur, means community variation may, in part,
be due to this parameter.
Although the sea fan Swiftia pallida is not listed as a characterising species in
.HCR.DpSp by Connor et al. (2004), the axinellid A. infundibuliformis is recorded as
characterising the Swiftia biotope. As the northern sea fan regularly occurs near or
within the .HCR.DpSp biotope in Scottish waters, it is possible that communities
containing northern sea fans with a high diversity and dominance of sponges may
represent the .HCR.DpSp biotope. The sea fan’s preference for habitats with a
reasonable tidal stream suggests that where the .HCR.DpSp biotope occurs in
areas of weak to moderate currents, the community may include S. pallida along
with species such as Tubularia sp. and the brittlestar Ophiocomina nigra. A
similar community to this was recorded by Howson et al. (2006) off the Isle of
Seil, Firth of Lorn.
Viability
A review by Hill et al. (2010) on deep-sea sponge aggregations concluded that there
was very little evidence on which to base an estimate of viable area size. These
habitats are difficult to study and recorded examples are limited in extent. Many
sponges reproduce asexually by fragmentation and budding, so some local
recruitment would be protected by a small area. Sexual reproduction may occur
seasonally, with the production of planktonic larvae (e.g. Geodia barretti, Hoffman et
al., 2003). The dispersal duration for sponge larvae ranges from a several hours to a
few days with an estimated maximum dispersal distance of 5km. Sponge larvae are
weak swimmers (Maldonado & Young, 1996) and Uriz et al. (1998), found that
variations in swimming behaviour of the larvae can play a significant role in the
dispersal ranges of different species. The dispersal ranges of key species are
currently unknown. However, characterising species such as Alcyonium digitatum
and Caryophyllia smithii have a much greater dispersal distance and, since they are
common in UK waters, a more continuous supply of larvae providing good
recruitment potential. Based on the above, it is recommended that the full, known
extent of examples of deep sponge communities are protected.
6
Longevity
Information indicates that many species of deep water sponges are slow growing,
possibly taking several decades to reach a large size (Klitgaard & Tendal, 2001). The
average lifespan of key species is unknown and although most sponge cells have the
capacity for indefinite proliferation (Koziol et al., 1998) it seems unlikely that
temperate species could attain the kind of ages reported from polar species.
Fragmentation
No information could be found regarding the level of fragmentation expected within
deep sponge communities.
Indicator of Least Damaged/More Natural
Up to date information on the sensitivity of deep sponge communities to pressures
associated with human activities are included, alongside other components, in the
Northern sea fan and sponge communities search feature assessment in the Feature
Activity Sensitivity Tool (FeAST; Marine Scotland, 2013). Below, Information on
indicators of naturalness and damage has been taken from the UK Biodiversity
Action Plans (Anon, 2008), supplemented by specific scientific papers (where
referenced) and MarLIN sensitivity data for dominant and frequently found sponges
of the deep sponge communities.
Table 1: Indicators of damage and naturalness
Indicators of Naturalness
Indicators of Damage
Community composition
Absence of older, larger
includes larger, older individuals. individuals within the
community.
Potential Sources of Damage
Removal of individuals for
research e.g. bio-prospecting
(Hoffman et al., 2003). Physical
disturbance (e.g. trawling)
(Freese et al., 1999;
Wassenberg et al., 2002)
Community composition
includes presence of intact
(undamaged) fragile sponges
and other fragile epifauna.
Absence of undamaged fragile
sponges and other fragile
epifauna within the community.
Physical disturbance (e.g.
trawling) (Freese et al., 1999;
Wassenberg et al., 2002)
Low levels of silt present, filter
feeders un-smothered. No
increases of silt tolerant species.
Elevated levels of silt present
with filter feeding organisms
exhibiting evidence of
smothering. Increases in
abundance of silt tolerant
species
Siltation/smothering
Community composition
comprising of typical species
(see biological diversity section).
Few ‘southern species’ present.
Increases in abundance of
‘southern species’ and/or
declines in characteristic
species within the community.
Increased ambient water
temperature possibly as a result
of climate change. (see Hiscock
et al., 2004)
Risk Assessment
The details of the assessment of risk for each MPA search feature is addressed in a
separate report (Chaniotis et al., 2014).
7
Recovery Potential
Little evidence was available on the recovery of deep sponge communities; however,
the presence of large, slow growing organisms may mean that full recovery, from
damage or loss of such individuals, could take many years. Warm shallow-water
sponge species have shown rapid recovery from physical disturbance (Freese et al.,
1999), yet it is thought that the slower growing, cold deep-water sponge species are
much more susceptible to physical damage (Freese, 2001; Hoffman et al., 2003).
The sponges represent a highly variable group of organisms with different
adaptations, life histories and morphologies. As such their susceptibility to
anthropogenic impacts varies; an example of this is documented by Wassenberg et
al. (2002) who found certain sponge morphologies to be more vulnerable to trawling.
Physical damage
Studies by Van Dolah et al. (1987) and Freese et al. (1999) found that 1 year after
trawl damage, numbers of warm shallow-water sponge species were at an equivalent
level to that pre-trawl. In contrast to this, a separate study of deep cold-water species
found that the impacts of trawling activity were much more persistent due to the
slower growth/regeneration rates of these species (Freese, 2001). Given the slow
growth rates and long life spans of the rich, diverse fauna, it is likely to take many
years for deep sponge communities to recover if adversely affected by physical
damage (Konnecker, 2002).
Elevated levels of siltation
A laboratory investigation carried out on the impact of elevated sedimentation rates
on deep water sponges (Hoffman & Tore Rapp, pers com) found that a sediment
load of 30 mg sed/l resulted in a significantly higher sponge mortality rate than was
seen in sponges exposed to 5 and 10 mg sed/l. It was also found that sponge
exposure to drill cuttings resulted in a significantly higher mortality rate than was
found with natural sediments.
Climate change
No evidence was available on how deep sponge communities could recover from an
increase in prevalence of southern species as a result of increases in ambient water
temperatures. Southern species currently recorded from northern Britain which might
increase in extent and abundance includes Axinella dissimilis, Hemimycale columella
and Alcyonium glomeratum (Hiscock et al., 2004).
8
Geographical Variation
Until recently there were no records of deep sponge communities in Scottish waters
and there is little information on their distribution around Scotland. Records exist
from the east coast of Shetland and the west and south coast of the Outer
Hebrides. They are considered to be more widespread than current data indicate
due to their tendency to be found in areas too deep for conventional diver survey. In
recent years an increasing number of remote surveys, using drop-down video and
ROV technologies, have allowed accurate records to be obtained (Roberts et al.,
2005). In addition, the biotope CR.HCR.DpSp (from the Connor et al., 2004
classification) is very similar to the 1997 biotope MCR.ErSSwi (Erect sponges and
Swiftia pallida on slightly tide-swept moderately exposed circalittoral rock; Connor
et al., 1997). It is thus quite possible that old records of MCR.ErSSwi might
represent the ‘deep sponge communities’ biotope (e.g. Davies, 1999).
Within the West Scotland MPA region both biotopes (.DpSp and .DpSp.PhaAxi) have
been recorded in territorial waters. Howson et al. (2006) recorded the .DpSp biotope
in the Firth of Lorn and there are a number of records for this biotope and the .PhaAxi
sub-biotope to the west of the Outer Hebrides (Mitchell, 2009). However, many of
these records are just outside the territorial boundary. There is also a mention of the
.PhaAxi sub-biotope by Roberts et al. (2005) during a survey of the Mingulay
Lophelia reefs.
A survey carried out by the research vessel Kommandor Jack in 2003 noted the
.PhaAxi sub-biotope at a number of sites off the east coast of Shetland offshore in
the North Scotland MPA region. There are also records of deep sponge communities
on Solan and Pobie Banks also in the North Scotland MPA region.
Geographical context
Around the rest of the UK, deep sponge communities are found in Wales; north and
west Anglesey, the Lleyn peninsula, in Pembrokeshire from Strumble Head in the
north to Stackpole in the south, excluding St Brides Bay. In England it can be found
in the south-west peninsula from west Dorset to Lundy; and in Ireland off the southeast coast.
9
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