BIOTIC Species Information for Corbula gibba
Click here to view the MarLIN Key Information Review for Corbula gibba
Researched byLizzie Tyler Data supplied byUniversity of Sheffield
Refereed byThis information is not refereed.
General Biology
Growth formBivalved
Feeding methodPassive suspension feeder
Active suspension feeder
Mobility/MovementBurrower
Environmental positionInfaunal
Typical food typesPhytoplankton, diatoms and bacteria. HabitFree living
Bioturbator FlexibilityNone (< 10 degrees)
FragilityIntermediate SizeSmall(1-2cm)
HeightInsufficient information Growth RateSee additional information
Adult dispersal potential100-1000m DependencyIndependent
SociabilityGregarious
Toxic/Poisonous?No
General Biology Additional InformationGrowth
Corbula gibba is a small bivalve mollusc. The growth rate of Corbula gibba is rapid during the first few months of its juvenile stage although it is very slow in adults (Jensen, 1990). In Nissum Bredning, Denmark the growth of juvenile Corbula gibba was rapid during their first two months (July-August) but leveled off in September and October at lengths ranging from 2.9-3.5 mm (Jensen, 1988). Thus juvenile Corbula gibba reached a size of 3 mm within the first 1-2 months after settling (Jensen, 1990). The absolute growth rate for that period was about 0.03 mm/day and remained constant until the end of August. No further growth was observed in September and October (Jensen, 1988). One year after juvenile settlement, specimens reached a mean size of 6 -7 mm. In the Limfjord (Denmark) it was suggested that the variation in growth rates was caused by variable frequencies of wind induced resuspension of settled organic matter. In the Limfjord wind speeds above Beaufort force 8 caused mixing of the water column and probably resuspension of bottom material in 1986. These conditions probably favour Corbula gibba as it is one of the most efficient bivalve particle feeders (Kiøboe & Mohlenberg, 1981). In 1985 the wind speeds never exceeded force 8 and no mixing was observed. This resulted in lower abundances of Corbula gibba and slower growth rates (Jensen, 1990).

Slower growth rates have been recorded in the Danish Sound where it took a population of Corbula gibba seven months to reach a mean size of 1.1 mm (Muss, 1973). Whereas in Port Erin on the Isle of Man it took one year for a population of juveniles to reach a mean size of 4 mm (Jones, 1956, Jensen, 1990). Jones (1956) also reported that the specimens of Corbula gibba on the Isle of Man had a modal length of 2.25 mm. Jensen (1990) suggested that the higher growth rates in the 1990's in Danish waters could be the result of specific events such as eutrophication. However, in Nissum Bredning no specimens were found over two years old in 1990. The size of Corbula gibba around the British Isles ranged from 0.5 mm in length to 1.2 cm in the 1940's (Yonge, 1946), and in Australian waters it can reach sizes up to 1.5 cm (CRIMP, 2000).

Abundance
Corbula gibba is often found in very large numbers and is often abundant in eutrophic areas (Pearson & Rosenberg, 1978). Corbula gibba are known to occur in enormous numbers, for instance 7450/m², at certain localities in the Atlantic (Healy & Lamprell, 1996). In the Limfjord, sampling of Corbula gibba was carried out at monthly intervals from April 1986 to May 1988. Ten samples were taken with a HAPS-corer (0.014 m²) and sieved over a 1 mm sieve (Jensen, 1990). The density for Corbula gibba ranged from 9,000 to around 53,000 per m². Newly settled Corbula gibba ranged from 30,000 and 67,000 individuals per m² (Jensen, 1988). In Pula Harbour in the Northern Adriatic, Corbula gibba was found at densities ranging from 33 -121 individuals / 0.2 m² (Hrs-Brenko, 1981). Corbula gibba is also found in Australia, outside of its native range, at densities of up to 250/m² in Port Philip Bay (CRIMP, 2000).

Biomass / Production
During 1974-1984 nitrogen concentration and primary production of specimens of Corbula gibba in Nissum Bredning increased from 50-100 % and 200-300 %. The production (P) of Corbula gibba is generally high. Productivity was measured over two years and ranged from 0.7-72 g AFDW (ash free dry weight) m²/ yr. with an average of 26.8g AFDW m² / yr. in Nissum Bredning. The production / biomass ratio was amongst the highest recorded with a mean P / B of 4:2 per year (Jensen, 1990).

Respiration
Laboratory studies have shown that Corbula gibba are able to survive long periods at near anoxic conditions. After 57 days, 9 out of 14 specimens survived 10 -11°C and oxygen levels of 0.18 to 0.37 mg oxygen per dm³ (Christensen, 1970).

Burrowing
Corbula gibba is a shallow burrowing bivalve with very short siphons (Yonge & Thompson, 1976). When placed on their normal substratum, individuals extrude their thin long foot to a distance that may exceed the length of its shell (Yonge, 1946). The process of burrowing is very slow. For example, an individual 1 cm long took about 30 minutes to burrow below the surface. This is slow when compared to other bivalve species, for example Abra alba that can disappear below the surface in less than a minute. It is the stout rounded shell that makes slow progress into the substratum, whereas Abra alba has a much flattened shell and foot therefore slides quickly into the substrata (Yonge, 1946).

Predators
Corbula gibba is consumed by gastropods, crustaceans, fish and echinoderms. Predators of Corbula gibba include the necklace shell Natica poliana (Jones, 1956), the sand star Astropecten irregularis (Christensen, 1970), the brittle star Ophiura texturata, the common starfish Asterias rubens, the common shore crab Carcinus maenas and the brown shrimp Crangon crangon (Jensen, 1988).

Non-native species
In Australia, Corbula gibba is an alien species and a pest (CRIMP, 2000). Corbula gibba is now widespread and highly abundant in Port Phillip Bay (Australia) (Talman, 1998; cited in Talman & Keough, 2001). Corbula gibba might affect endemic Australian species via habitat modification, predation on planktonic larvae, and competition. It also possesses a number of characteristics that may give it a competitive advantage over Australian endemic species, such as the capacity for fast growth and the ability to tolerate a wide range of environmental conditions including anoxia and eutrophication (Jensen, 1990; Talman & Keough, 2001). Concern has arisen in Australia regarding the impact of Corbula gibba on the commercial scallop Pecten fumatus. Corbula gibba and Pecten fumatus overlap in distribution, and as suspension feeders, it has been suggested that they utilize similar food and therefore may be competing for space and food (Talman & Keough, 2001). It was found that ambient densities of Corbula gibba had a significant impact on the size and growth of the native juvenile Pecten fumatus but not on mortality rates (Talman & Keough, 2001). Scallops in the presence of Corbula gibba had shells that were, on average, 35% lighter, 24% smaller and exhibited 54% less growth (based on caging experiments) (Talman, 2000: cited in NIMPIS, 2002). As a result of these concerns Australian authorities have developed new methods to control the spread of Corbula gibba. However, measures such as dredging / beam trawling / mopping, changing salinity and oxygen deprivation have all proved relatively unsuccessful (McEnnulty et al., 2001a).

Biology References Jensen, 1990, Rasmussen, 1973, Lauckner, 1983, Jensen, 1988, CRIMP, 2000, Kiørboe & Møhlenberg, 1981, Hrs-Brenko, 1981, Yonge, 1946, Jones, 1956, Yonge & Thompson, 1976, Muus, 1973, Pearson & Rosenberg, 1978, Talman & Keough, 2001, Christensen, 1970, McEnnulty et al., 2001a, NIMPIS, 2002, Healy & Lamprell, 1996, Hayward & Ryland, 1990,
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