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

The sponge is attached to the substratum and is unlikely to survive substratum loss. However, settlement of new colonies is likely within one year and growth rate is almost certainly 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

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

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, tolerant is suggested.

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 bowerbanki may occur under overhangs and in damp places on the lower shore but does not live in such open conditions as Halichondria panicea. Desiccation would be likely to have a significant adverse effect on the sponge with bleaching and tissue death likely at the edges of the colony. Regrowth will most likely occur rapidly as growth is likely from remaining tissue or settlement. However, for the level of the benchmark, an intolerance of intermediate is suggested with a recoverability of high.

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 and established colonies are likely to be significantly damaged and lost at the upper limit of their intertidal range. The species prefers subtidal habitats and Vethaak et al. (1982) described intertidal colonies of Halichondria bowerbanki in the Oosterschelde as undersized. Where emergence is increased, intertidal colonies will most likely be killed and so, with reference to intertidal colonies, intolerance is assessed as 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

The species is mainly subtidal so that a decrease in emergence that makes intertidal species subtidal will benefit the species.

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

Halichondria bowerbanki is tolerant of various hydrographic regimes (Vethaak et al., 1982). The species is found in locations exposed to strong tidal flow but, where it is growing in habitats where tidal streams are normally weak, an increase in flow may result in damage to the colonies through tearing-off of erect structures or by poorly attached massive growths being swept away. The substratum may also be dislodged in part through the drag caused by the sponge. Feeding may be inhibited by strong flow.  However, damage is likely to be rapidly repaired (see Bowerbank, 1857) and mortality is unlikely to be total with re-growth occurring once water flow rates return to normal. An intolerance of intermediate with a very high recovery has been suggested.

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

Halichondria bowerbanki has been recorded in isolated lagoons with no water movement in the Oosterschelde (Vethaak et al., 1982).  Although small in its upper range, larger specimens were found growing lower down. A reduction in water flow rates in situations sheltered from wave action may lead to a reduced food supply and possible local de-oxygenation although in general, an intolerance of low has been suggested since mortality is unlikely.

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 bowerbanki 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 bowerbanki 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.

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 bowerbanki was found to occur in higher population densities on more shaded and totally dark surfaces compared to well lit areas in the Oosterschelde (Vethaak et al., 1982). It may extend its range to shallow areas previously dominated by algae if turbidity increases. However, change in turbidity may be caused by increased suspended sediment levels which may clog feeding pores or cause expenditure of energy to clean colonies (see Increase in suspended sediment above). On balance, 'tolerant' is 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 bowerbanki occurs in low light levels and algae may encroach the upper limits of its range if turbidity declines and light levels increase. If the change in turbidity is caused by decreased suspended sediment levels, sponges will expend less energy in cleaning. On balance, tolerant is 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

The shape of sponge colonies is influenced heavily by the hydrodynamics of the environment and, in ‘high stress’ environments such as very wave exposed areas, the colonies are often undersized or encrusting (Vethaak et al., 1982). Colonies of Halichondria bowerbanki live in areas sheltered from wave action and, where wave exposure increases, some large and poorly attached colonies may be displaced. For a closely related species, Halichondria panicea, 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. Intolerance is assessed as intermediate and recoverability as high.

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 bowerbanki thrive in areas sheltered from wave action so that they would be expected to benefit from a decrease in wave action.

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.  However, where merely damaged, repair is likely to occur very rapidly as in the related Halichondria panicea (Bowerbank, 1857) whilst 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 abrasion. Therefore, an intolerance of intermediate is suggested with a recoverability of high.

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. It is possible that detached colonies that become trapped under boulders or in fissures may re-attach. 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 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 the similar species 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 bowerbanki is euryhaline (Vethaak et al., 1982) and occurs in areas subject to full and low salinity and tolerant has been suggested.

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 bowerbanki is euryhaline and has been recorded in polyhaline lagoons in the Oosterschelde (Vethaak et al., 1982). It seems likely that it will survive acute changes for a few days because the sponge grows in areas subject to high freshwater outflow in periods of heavy river flow and, overall, tolerant has been suggested.

Changes in oxygenation

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

Evidence

Halichondria bowerbanki 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 2mg/l.   However, no information was found concerning the tolerance of Halichondria bowerbanki 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 bowerbanki. The similar sponge Halichondria panicea 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

There are no alien species currently known to compete with or adversely affect Halichondria bowerbanki.

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 recorded for the similar Halichondria panicea (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

The species is not known to be associated with other species that might be extracted.