Nucula

A Intermediate genera from the “Molluscs” group, mostly found in Muddy Sandy Gravel

Muddy Sandy Gravel

Intermediate

Molluscs

Genera Characteristics Recorded Traits Possible Values
Size in cm
  • 1-10 cm
  • <1 cm
  • 1-10 cm
  • 11-20 cm
  • >20 cm
Genera Characteristics Recorded Traits Possible Values
Motility (Adult)
  • Short Range Mobility
  • Adult
  • Short Range Mobility
  • Sedentary

“Short Range Mobility”

Motility (Larval)
  • Short Term Planktonic
  • Long Term Planktonic
  • Short Term Planktonic
  • Brooded or Laid Eggs

“Short Term Planktonic”

Lifespan
  • 3-10 years
  • >10 years
  • 3-10 years
  • 1-2 years
  • <1 year
Maturity
  • 1-2 years
  • >4 years
  • 3-4 years
  • 1-2 years
  • <1 year
Fecundity
  • 10 - 100
  • 100 - 1000
  • 1000 - 10000
  • 1 - 10
  • 10 - 100
  • 100 - 1000
  • 1000 - 10000
  • 10000 - 1 million
  • > 1 million

Image: Nucula © MES

Vulnerability

Nucula is a genus of small bivalve molluscs belonging to the Family Nuculidae (Nut shells). The shell length is 1-2cm & the bivalve lives in muddy sand, in coarse sands & gravel depending on species. It is a selective deposit-feeder exploiting material near the sediment surface. It is a moderately mobile burrower & can be found from a few mm to a few cm deep. It is vulnerable to dredging but is probably tolerant of moderate deposition of sediments mobilised during the dredging process.
 

Recoverability

Nucula has a life-span of about 6-10yrs & reaches sexual maturity after 1-2yrs. The sexes are separate & spawning is mainly in the autumn, although in some areas spawning occurs from June-September. There is considerable species variation in the number of eggs produced (from 20 to 4500). Eggs are about 0.1-0.15mm in size with a high lipid content are produced & these settle within 2-6 days to form locally dense communities on the seabed. This genus has a capacity for dense recolonisation in suitable areas but the restricted dispersal implies a low recoverability from outside the area if the adult breeding population is removed by dredging.

 

References

  • Biology

    • Allen, 1953b
    • Allen, 1954
    • Davis & Wilson, 1983b
    • Davis & Wilson, 1985
    • Edwards, 1965
    • Ford, 1925
    • Hayward & Ryland, 1990
    • Julie Bremner, unpub data
    • Petersen, 1977
    • Rachor & Salzwedel, 1976
    • Rachor, 1976
    • Ruppert & Barnes, 1994
    • Tebble, 1976
    • Yonge, 1939
  • Taxonomy

    • Allen, 1954
    • Gibson et al., 2001
    • Hayward & Ryland, 1995b
    • Howson & Picton, 1997
    • Tebble, 1976
  • Distribution

    • Bruce et al., 1963
    • Hayward & Ryland, 1990
    • Hayward & Ryland, 1995b
    • JNCC, 1999
    • Julie Bremner, unpub data
    • NBN, 2002
    • Picton & Costello, 1998
    • Rachor, 1976
    • Seaward, 1982
    • Tebble, 1976
  • Reproduction

    • Allen, 1953b
    • Allen, 1954
    • Davis & Wilson, 1983a
    • Davis & Wilson, 1983b
    • Davis & Wilson, 1985
    • Julie Bremner, unpub data
    • Lebour, 1938
    • Rachor, 1976
    • Scheltema and Williams, 2009
    • Wilson, 1992