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

Vethaak et al.,(1982) recorded apparently free-living forms of Halichondria panicea rolling around on the seabed near Dogger Bank in the North Sea although it is not known whether these specimens had once been attached and survived displacement from the substratum. It is most likely that sponges attached to the substratum are unlikely to survive substratum loss. However, settlement of new colonies is likely within one year and growth rate is rapid. Therefore, intolerance and recoverability have been recorded as high.

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

It is unlikely that Halichondria panicea will survive smothering for any significant length of time as the colony relies on water movement for respiration and has no mechanism for expanding above smothering material. Although the sponge has a mechanism for sloughing off their complete outer tissue layer together with any debris (Bartel & Wolfrath, 1989) there is probably an energetic cost in clearing sediment from tissues. Furthermore, Vethaak et al. (1982) reported that Halichondria panicea were rarely found in silt covered areas in the Oosterschelde. Therefore an intolerance of high has been recorded. However, settlement of new colonies is likely within one year and growth rate is rapid. Hence, a recoverability of high has been recorded.

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

Halichondria panicea lives in situations such as the entrance to estuaries and in straits where suspended sediment levels and settlement of silt is often high. The sponge has a mechanism for sloughing off their complete outer tissue layer together with any debris (Bartel & Wolfrath, 1989). It is expected that the sponge can, therefore, cope with increased siltation rates and suspended sediment. However, there is probably an energetic cost in clearing sediment from tissues and therefore, an intolerance of low has been recorded.

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

The sponge may derive some benefit from organic matter as food in the suspended sediment but there is probably an energetic cost in clearing sediment from tissues. On balance, this species has been assessed as tolerant.

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

Halichondria panicea is able to withstand some desiccation, in part because the tissue holds water. However, damage may occur if desiccation levels increase from those to which established individuals are normally exposed. Bleaching and tissue death is likely at the edges of the colony but re-growth will most likely occur.

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

Desiccation is likely to be the main impact of increased emergence. Established colonies may however survive but not thrive. The sponge is able to withstand some desiccation in part because the tissue holds water. However, damage may occur if desiccation levels increase from those to which established individuals are normally exposed. Bleaching and tissue death is likely at the edges of the colony but re-growth will most likely occur.

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

The species occurs in the subtidal so that a decrease in emergence that makes intertidal colonies subtidal will benefit the species. However, in the subtidal, colonies may be subject to greater predation and so, on balance, tolerant is suggested.

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

In the Oosterschelde, Vethaak et al. (1982) reported that the biomass of Halichondria panicea was extremely high in stream gullies in the sublittoral associated with high water flow rates. In the case of increased water flow rates, low-lying colonies are unlikely to be adversely affected and may grow to a large size (favourable effect). However, poorly attached massive growths may be torn-off or swept away. Mortality is unlikely to be total and repair (see Bowerbank, 1857) and re-growth will occur once water flow rates return to normal. Growth is rapid (about 5% increase per week: Barthel, 1988).

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

A reduction in water flow rates in situations sheltered from wave action will most likely have an adverse effect on at least a proportion of colonies through reduced food supply and possible local deoxygenation. However, it is not thought that this would result in death and, therefore, an intolerance of low has been recorded.

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

Halichondria panicea has a wide distribution in the north-east Atlantic with Britain and Ireland central to that distribution so that the species exists well-within its normal temperature survival range.

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

Halichondria panicea has a wide distribution in the north-east Atlantic with Britain and Ireland central to that distribution so that the species exists well-within its normal temperature survival range. However, Crisp (1964) noted that colonies were damaged by frost during the 1963/64 winter. Recovery from surviving tissue is likely to be rapid and re-colonization will occur from annual recruitment from the plankton.

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

Halichondria panicea occurs in low light levels. Furthermore, Vethaak et al. (1982) reported that Halichondria panicea had much higher population densities on shaded / totally dark surfaces than on well lit ones. The symbiotic algae that occur in the tissue in intertidal and shallow subtidal situations are likely to at least decline in abundance as a result of higher turbidity levels but not affect the survival of the sponge. Overall, tolerant* has been suggested.

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

Halichondria panicea occurs in low light levels. The symbiotic algae that occur in the tissue in intertidal and shallow subtidal situations are likely to increase in abundance as a result of lower turbidity levels but this will not affect the survival of the sponge and tolerant has been suggested.

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

Colonies of Halichondria panicea require water movement, whether wave action or tidal streams and, where wave exposure increases, some large and poorly attached colonies may be displaced by the wave action. The shape of sponge colonies is greatly influenced by the hydrodynamics of the environment and in high stress environments (such as high wave exposure), the sponges are often undersized or encrusting (Vethaak et al., 1982). Overall, intolerance has been assessed as intermediate as biomass is expected to decrease. However, the growth rate is rapid (about 5%; increase per month: Barthel 1988) and recovery would be expected to occur quickly after reversion to previous conditions.

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

Colonies of Halichondria panicea require water movement, whether wave action or tidal streams. Reduction in wave exposure at sites where tidal streams are slight or absent may result in at least a reduction in growth and therefore an intolerance of low is suggested.

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

Sponges have no known receptors for noise.

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

Sponges have no known visual receptors.

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

The sponge is attached to the substratum and is unlikely to survive abrasion and physical disturbance. Therefore, an intolerance of intermediate is suggested. However, where merely damaged, repair occurs very rapidly (Bowerbank, 1857) whilst the settlement of new colonies is likely within one year and the growth rate is rapid. Sponges may also regrow from tissue remaining in crevices or other irregularities and that were not affected by the abrasion.

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

The sponge is attached to the substratum and is unlikely to survive being detached and displaced even though it remains in the area unless the location is very sheltered from disturbing conditions such as wave action. However, settlement of new colonies is likely within one year and growth rate is rapid. Sponges may also regrow from tissue remaining in crevices or other irregularities and that were not affected by the displacement.

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

Insufficient
information

Heavy metal contamination

Evidence

Insufficient
information

Hydrocarbon contamination

Evidence

Very little information has been found. It appears that Halichondria panicea survived in areas affected by the Torrey Canyon oil spill (Smith, 1968), although few observations were made. If mortality occurred, settlement of new colonies is likely within one year and growth rate is rapid.

Radionuclide contamination

Evidence

Insufficient
information

Changes in nutrient levels

Evidence

Insufficient
information

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

Halichondria panicea is euryhaline, occurring from full to low salinity conditions. Although it was not found in a mesohaline (5-18) lagoon in the Oosterschelde, it did survive in a polyhaline (18-30) lagoon, albeit as a thin encrusting base (the effects of the siltation were thought to be responsible for this as opposed to the reduced salinity conditions). Settlement of new colonies is likely within one year and the growth rate is rapid.

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

Halichondria panicea occurs from full to low salinity conditions and only prolonged exposure to fresh or almost fresh water is likely to result in mortality. Settlement of new colonies is likely within one year and growth rate is rapid.

Changes in oxygenation

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

Evidence

Halichondria panicea lives in areas of flowing water, which suggests that it is likely to need a good supply of oxygen for survival. Cole et al. (1999) suggest possible adverse effects on marine species below 4 mg/l and probable adverse effects below 2 mg/l.   However, no information was found concerning the tolerance of Halichondria panicea to changes in oxygenation. Settlement of new colonies is likely within one year and the growth rate is rapid.

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 literature was found concerning diseases and parasites in Halichondria panicea. The sponge has a mechanism for sloughing off the outer tissue layer (Bartel & Wolfrath, 1989) which may also be a means of removing pathogens or epizooites.

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

Insufficient
information

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

No targeted extraction of this species is known. Were it to be extracted, it is expected that tissue would be left behind and would regrow. Growth rates of about 5% per week are likely (Barthel, 1988).

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

Halichondria panicea colonizes Laminaria hyperborea stipes and may thus be subject to harvesting effects. Sivertsen (1991; cited in Birkett et al., 1998) showed that kelp populations stabilise after about 4-5 year post-harvesting and Halichondria panicea will settle readily so that recovery is likely to occur within a  year or possibly more.