BIOTIC

BIOTIC Species Information for Conopeum reticulum

Researched by

Dr Harvey Tyler-Walters & Susie Ballerstedt

Data supplied by

MarLIN

Refereed by

Dr Peter J. Hayward

Reproduction/Life History

Reproductive type

Permanent hermaphrodite
Budding

Developmental mechanism

Planktotrophic

Reproductive Season

June to October

Reproductive Location

Insufficient information

Reproductive frequency

Annual episodic

Regeneration potential

Life span

Insufficient information

Age at reproductive maturity

<1 year

Generation time

<1 year

Fecundity

See additional information

Egg/propagule size

Fertilization type

Insufficient information

Larvae/Juveniles
Larval/Juvenile dispersal potential	>10km	Larval settlement period
Duration of larval stage	1-6 months

Reproduction Preferences Additional Information

Reproduction
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.

Recruitment
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,