Mytilus edulis (Blue Mussel)

By: Jody-lee Goosen(2864987) Allison Jacobs(2855443)

Biology, Ecology and Distribution

• Mussels are found within the family Mollusca [Coe & Fox (1943)].

• Mytilus edulis is an important element on the rocky coasts as well as on many intertidal zones [Clark, et.al (1990)].

• Mussel beds are found on the seaward side of estuaries [Clark, et.al (1990)].

• Environmental conditions are thought to be responsible for the differences in growth rate within a population [Coe &Fox (1943)].

Estimating Population Size

• In order to determine the population size one first has to determine the birth and death rate of the population [Caldow et.al (1995)].

• Mussels become adults when they are 2 years old and die out at the age of 10 [Clark, et.al (1990)].

• In order for us to calculate the population size one has to determine the density of each age group within a cohort [Clark, et.al (1990)].

Methodology

• To estimate the population size one has to firstly divide a large area within the benthic into

smaller mussel beds with equal area sizes [Clark, et.al (1990)].

• Some beds were divided into sub-areas depending on the size and density of the mussel [Clark, et.al (1990)].

• The internal shell structure of the individual is then observed in order to determine a growth curve [Naylor, et.al (1990)].

Growth curves

• In determining the population size, one would use the growth curve of the individual mussel [Naylor, et.al (1990)].

• The growth curve would illustrate the mean growth rate within a population [Naylor, et.al (1990)].

Estimating population age

• The process of aging is a popular topic and has been studied for many years [Abele, et.al (2002)].

• There are two major theories concerning age

of invertebrates, namely “Rate of living” theory and the “Free living” theory [Abele, et.al (2002)].

• Invertebrates grow throughout their lifespan, therefore their age can be determined by their growth [Thompson RJ (1984)].

Methodology

• Mussel age can be determined by counting

their internal rings [Clark, et.al (1990)].

• Age can also be determined by counting the winter rings on the shells of muscles [Abele, et.al (2002)].

• It has been determined that growth lines can

be determined annually [Thompson RJ (1984)].

ReferencesMcGrovty S, Clark RT, Reading CJ, Cross-Custard JD(1990).Population dynamics of the mussel Mytulis edulis density changes and regulation of the population in the Exe estuary, devon. Marine ecology progress series 67: 157-169Richardson CA, Seed R, Naylor E.(1990). Use of internal

growth bands for measuring individuals and population

growth rates in Mytulis edulis from offshore production platforms. Marine ecology progress series 66: 259-265Sukhotin AA, Abele D, Pother HO.(2002). Grow ,metabolism

and lipid peroxidation in Mytulis edulis :age and size effects. Marine ecology series 226: 223-234

ReferencesThompson RJ (1984). production, reproductive effort, reproductive value and reproductive cost in a population of

the blue mussel Mytilus edulis from a subarctic environment. Marine ecology-progress series 16: 249- 257Coe WR, Fox DC (1943). biology of the California sea mussel (Mytilus californianus). Environmental conditions and rate of growth. Scripps Institution of oceanography, University of California, La Jolla (1): 57-60