Density dependent effects control the reproductive strategy and population growth of Aurelia aurita s.l. scyphistomae

SCHIARITI, A.; MELICA, V.; KOGOVEK, T.; MALEJ, A.

MARINE BIOLOGY

SPRINGER

Lugar: Berlin; Año: 2015 vol. 162 p. 1665 - 1672

0025-3162

Aurelia auritas.l.scyphistomae are capable of developing different asexual modes for Propagation andthus present a multi-mode reproductive strategy. The reproduction rates and thereproductive strategy they adopt depend on a combination of variousenvironmental parameters. We investigated the A. aurita s.l.polyp-to-polyp reproduction strategy and population growth in relation topolyp density.Our results confirmed that density-dependent factors control population growthof A. aurita s.l.scyphistomae in three different ways: (1) decreasing the polyp reproductionrate, (2) triggering the production of motile bud-like tissue particles and (3)inducing the detachment of developed scyphistomae. Whereas the decrease in the reproductionrate reduces the number of recruits, the motile particles and the detachment ofscyphistomae contribute to minimizing density-dependent effects by allowingreproductive products and scyphistomae to drift away. Thus, not only are thenegative effects of intraspecific competition for space and food diminished butalso the potential colonization of new substrates, and further increase inscyphistoma density is favoured on larger spatial scales. The potential capabilityto switch its polyp-to-polyp reproduction strategy in response to environmentalclues and population density may give Aurelia highadaptability in the temperate coastal waters where they commonly live and wherethey may be exposed to wide-ranging and fluctuating environmental variablesthat affect their survival and longevity. Considering these features, as wellas the wide tolerance of Aurelia scyphistomae (and medusae) to environmental parameters,it is not surprising that the species/lineages of Aurelia arecosmopolitan and exhibit the most frequent bloom events worldwide.