BIOTIC Species Information for Conopeum reticulum
Researched byDr Harvey Tyler-Walters & Susie Ballerstedt Data supplied byMarLIN
Refereed byDr Peter J. Hayward
Scientific nameConopeum reticulum Common nameAn encrusting bryozoan
MCS CodeY172 Recent SynonymsNone

PhylumBryozoa Subphylum
Superclass ClassGymnolaemata
Subclass OrderCheilostomatida
Suborder FamilyMembraniporidae
GenusConopeum Speciesreticulum

Additional InformationNormal autozooids occasionally become irregularly shaped or larger, especially at the edges of colonies where there are sometimes large, irregular gaps to fill.
Taxonomy References Hayward et al., 1996, Hayward & Ryland, 1995b, Hayward & Ryland, 1998, NBN, 2002, Howson & Picton, 1997, Ryland, 1970, Ryland, 1976, Hincks, 1880, Ryland, 1967,
General Biology
Growth formCrustose hard
Feeding methodActive suspension feeder
Mobility/MovementPermanent attachment
Environmental positionEpifaunal
Typical food typesPhytoplankton (<50µm), macroalgal spores, detritus, and bacteria. HabitAttached
BioturbatorNot relevant FlexibilityNone (< 10 degrees)
FragilityFragile SizeSmall-medium(3-10cm)
HeightInsufficient information Growth RateSee additional information
Adult dispersal potentialNone DependencyIndependent
General Biology Additional InformationGrowth rates
Growth, measured in zooid number, in Conopeum reticulum is exponential (Menon, 1972). Growth rates in bryozoans have been shown to vary with environmental conditions, especially, food supply, temperature, competition for food and space, and genotype. For example, although growth rates increased with temperature, zooid size decreased, which may be due to increased metabolic costs at higher temperature (Menon, 1972; Ryland, 1976; Hunter & Hughes, 1994). Menon (1972) reported that in culture, growth in Conopeum reticulum reached a plateau after about 30 days and that the growth rate had significantly reduced at the end of 6 months. In his experiments Conopeum reticulum colonies grew to ca 1000 zooids within ca 28 days at 12 °C and ca 18 days at 22 °C, although these rates were slower than under natural conditions (Menon, 1972). Feeding rates also varied with respect to temperature (Menon, 1974).

The structure and function of the bryozoan lophophore was reviewed by Ryland (1976), Winston (1977) and Hayward & Ryland (1998). Ambient water flow is important for bringing food bearing water within range of the colonies own pumping ability (McKinney, 1986). Best & Thorpe (1994) suggested that intertidal Bryozoa would probably be able to feed on small flagellates, bacteria, algal spores and small pieces of abraded macroalgae.

Biology References Hayward & Ryland, 1998, Ryland, 1970, Ryland, 1976, Winston, 1977, Best & Thorpe, 1994, Menon, 1972, Hunter & Hughes, 1994, Menon, 1974, Ryland, 1967,
Distribution and Habitat
Distribution in Britain & IrelandRecorded in a few locations on the west coast of Scotland (but probably more widespread (P. Hayward, pers. comm.)) and the north east of England. It is more common around the coast of Wales and along the south coast of Britain.
Global distributionPresent in the Kattegat and shores of the southern North Sea. Recently recorded in the western Mediterranean.
Biogeographic rangeNot researched Depth rangeIntertidal to at least 42m
Distribution Additional InformationThe distribution may be imprecise since Conopeum reticulum is frequently confused with other species but it is probably common off all British coasts (Hayward & Ryland, 1998). Conopeum reticulum has been reported from a wide variety of hard substrata including boulders, cobbles, shell and small stones on sediment, as well as the shells of %Mytilus edulis%. Colonies inhabiting stones and cobbles are probably ephemeral, removed by abrasion and rolling during winter storms. Grant & Hayward (1985) reported Conopeum reticulum in shallow water bryozoan assemblages in the English Channel at a mean depth of 42m.

Substratum preferencesAlgae
Artificial (e.g. metal/wood/concrete)
Large to very large boulders
Other species (see additional information)
Small boulders
Under boulders
Physiographic preferencesEstuary
Open coast
Strait / sound
Ria / Voe
Enclosed coast / Embayment
Biological zoneLower Eulittoral
Sublittoral Fringe
Upper Infralittoral
Lower Infralittoral
Wave exposureExposed
Moderately Exposed
Very Sheltered
Extremely Sheltered
Tidal stream strength/Water flowStrong (3-6 kn)
Moderately Strong (1-3 kn)
Weak (<1 kn)
SalinityVariable (18-40 psu)
Full (30-40 psu)
Reduced (18-30 psu)
Habitat Preferences Additional Information
Distribution References Hayward et al., 1996, Hayward & Ryland, 1995b, Hayward & Ryland, 1998, NBN, 2002, Ryland, 1970, Ryland, 1976, Grant & Hayward, 1985, Cook, 1964, JNCC, 1999, JNCC, 1999, Hincks, 1880, Ryland, 1967,
Reproduction/Life History
Reproductive typePermanent hermaphrodite
Developmental mechanismPlanktotrophic
Reproductive SeasonJune to October Reproductive LocationInsufficient information
Reproductive frequencyAnnual episodic Regeneration potential No
Life spanInsufficient information Age at reproductive maturity<1 year
Generation time<1 year FecunditySee additional information
Egg/propagule size Fertilization typeInsufficient information
Larval/Juvenile dispersal potential>10km Larval settlement period
Duration of larval stage1-6 months   
Reproduction Preferences Additional InformationReproduction
Bryozoan colonies are hermaphrodite, however, zooids may be monoecious, dioecious, protandrous or protogynous, depending on species (Hayward & Ryland, 1998). In most bryozoans the zooids are hermaphrodite and probably protandric, becoming male then female (Reed, 1991; Hayward & Ryland, 1998). Sperm are shed from pores in the polypide tentacles of male zooids (Hayward & Ryland, 1998). In bryozoans, released sperm are entrained by the tentacles of female polypides and may not disperse far, resulting in self-fertilization. However, genetic cross-fertilization is assumed in most bryozoans, although there is evidence of self fertilization (Reed, 1991; Hayward & Ryland, 1998). Female zooids develop a ciliated intertentacular organ, which collects eggs from the ovaries, passes them to the gonopore, and expels them beyond the lophophores during spawning (Reed, 1991). Fertilization is thought to occur either within the tentacular organ or just as eggs are spawned (Ryland, 1976; Reed 1991).
Conopeum reticulum breeds between June and early October in the Britain and Ireland, and yellowish-white, rounded eggs (average size 110 by 80µm) were present from July to September in the River Crouch (Cook, 1964; Hayward & Ryland, 1998). Cook (1964) reported that eggs were rarely spawned in daylight but that many were found in the morning. Day length is an important cue for spawning in some coastal species of bryozoa that spawn in the first few hours of daylight (Hayward & Ryland, 1998).

Cook (1964) reported that the intertentacular organ contained 5-9 eggs per zooid. However, while each individual zooid is not prolific, the fecundity of the colony is probably directly proportional to the number of functional zooids (Bayer et al., 1994) and is probably high. Although Conopeum reticulum colonies could probably survive for several years, it is probably adapted to ephemeral habitats, capable of rapid growth and reproduction of numerous offspring (r-selected).

Larvae were present in the plankton in the same period (July to September) in the River Crouch and River Blackwater (Cook, 1964). Reed (1991) reported that planktotrophic cyphonautes larvae spend between one to three months in the plankton.

Bryozoan larvae are probably sensitive to surface contour, chemistry and the proximity of conspecific colonies. However, Hayward & Ryland (1998) suggested that larval behaviour at settlement is only of prime importance to species occupying ephemeral habitats. Eggleston (1972b) demonstrated that the number and abundance of species of bryozoan increased with increased current strength, primarily due to a resultant increase in the availability of stable, hard substrata (Eggleston, 1972b; Ryland, 1976). Ryland (1976) reported that significant settlement in bryozoans was only found near a reservoir of breeding colonies. Ryland (1977) suggested that marine bryozoan larvae tend to settle on the underside of submerged structures or in shaded habitats, possibly due to avoidance of accumulated sediment or competition from algae. However, Conopeum reticulum larvae have an extended planktonic life and Conopeum reticulum is a member of fouling communities (Ryland, 1967). In addition, Conopeum sp. have been reported to have spread into the Caspian Sea after the opening of the Volga-Don canal, possibly on shipping (Ryland 1967). Therefore, Conopeum reticulum probably exhibits good dispersal and potentially very rapid recruitment. For example, Hatcher (1998) reported that spring recruitment to an artificial reef in Poole Bay was dominated by tubeworms and encrusting bryozoans including Conopeum reticulum. Conopeum reticulum colonized artificial reef surfaces within 6 months from May to October 1991 (Hatcher, 1998).
Reproduction References Hayward & Ryland, 1998, Ryland, 1970, Ryland, 1976, Cook, 1964, Bayer et al., 1994, Eggleston, 1972b, Hatcher, 1998, Ryland, 1967,
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