Summary
Brief Summary
Classification
Names
Physical Description
General Body Plan
The Tentacles
Colouration
Ecology
Habitats
Crypsis
Larvae
Behaviour
Overview
Feeding
Predatory Defense Mechanisms
Survival Mechanisms
Reproduction
Reproductive Characteristics
Reproductive Strategy
Case Study
Ecological Role
Overview
Secondary Production
Sediment Processing
Biogeographic Distribution
Life History
Larval Development
Building of Sandy Tube
Early Benthic Development
Conservation and Threats
References & Links | Reproductive Characteristics
There is limited data available regarding the life history, population dynamics and reproductive strategies of L. medusa, and some information surrounding the species is still under investigation.
L. medusa individuals are monotelic, in that they breed once per lifetime at which point the gametes are released in one or more large batches Olive and Clark 1978). From the data available reproduction occurs throughout the summer months, but each localised population exhibits their own reproductive synchrony relative to the lunar cycle (R. Seitz & L. Schaffner, 1995). Such data also suggests that a minimum of two cohorts may recruit to the population each year. The effect this has on the population dynamics of each regional population is the emergent pattern of a population with an overwintering cohort which produce one or more rapidly growing summer cohorts (R. Seitz & L. Schaffner, 1995). In turn summer-spawned individuals, who have sufficiently higher growth and maturation rates than winter-spawned individuals, spawn during the same season to produce at least one cohort which will overwinter into the following year (R. Seitz & L. Schaffner, 1995). Seasonal variation in L. medusa larval abundances recorded have been strongly correlated with seasonal changes in temperature. The adaptive significance of reproductive timing with respect to seasons or lunar activity remains somewhat uncertain, but is most likely to involve predator avoidance, increased dispersal capability or increased fertilization efficiency with synchronous swarming or spawning (Jacoby and Greenwood, 1989).
L. medusa has exceptional fecundity; however this alone is not enough to ensure successful recruitment within ecosystems such as estuaries in which dynamic physical processes combine with biological factors to determine the magnitude and timing of settlement (R. Seitz & L. Schaffner, 1995). Multiple spawning events have been observed during a single season to ensure successful recruitment of the local adult population.
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