BIOTIC Species Information for Zostera noltii
|Researched by||Dr Harvey Tyler-Walters||Data supplied by||MarLIN|
|Refereed by||Dr Leigh Jones|
|Reproductive Season||May to September||Reproductive Location|
|Reproductive frequency||Annual protracted||Regeneration potential||No|
|Life span||1 year||Age at reproductive maturity||1-2 years|
|Generation time||1-2 years||Fecundity||Insufficient information|
|Egg/propagule size||Fertilization type|
|Reproduction Preferences Additional Information||Zostera sp. are monoecious perennials but may be annuals under stressful conditions (Phillips & Menez 1988). Hootsmans et al. (1987) reported that each flowering shoot of Zostera noltii produces 3-4 flowers containing 2-3 seed each. They estimated a potential seed production of 9000/m² based on the maximum density of flowering shoots in their quadrats in the Zandkreek, Netherlands. Most seeds were released in August in the Zandkreek but the actual seed densities were much lower than predicted (Hootsmans et al., 1987). However, the density of flowering shoots is highly variable.
Eelgrass reproduces vegetatively, i.e. by growth of rhizome. Vegetative reproduction probably exceeds seedling recruitment except in areas of sediment disturbance (Reusch et al. 1998; Phillips & Menez 1988). Phillips & Menez (1988) state that seedling mortality is extremely high. Fishman & Orth (1996) report that 96% of Zostera marina seeds were lost from uncaged test areas due to transport (dispersal) or predation. Hootsmans et al. (1987) noted that potential recruitment was maximal (32% of seeds) at 30 °C and 10psu, and no recruitment occurred at 30psu. and they estimated that, in 1983 <5% of Zostera noltii plants in the Zandkreek originated from seed.
Phillips & Menez (1988) note that seedlings rarely occur within the eelgrass beds except in areas cleared by storms, blow-out or excessive herbivory. Den Hartog (1970) noted that although the seed set was high, Zostera noltii seedlings were rarely seen in the wild, suggesting that vegetative reproduction may be more important than sexual reproduction (Davison & Hughes, 1998). Experimental germination was increased by low salinity (1-10 psu) in Zostera noltii and no germination occurred at salinities above 20 psu, however germination was independent of temperature (Hughes et al., 2000).
Zostera sp. flowers release pollen in long strands, dense enough to remain at the depth they were released for several days, therefore, increasing their chance of pollinating receptive stigmas. Seeds develop within a membranous wall that photosynthesises, developing an oxygen bubble within the capsule, eventually rupturing the capsule to release the seed. Seeds generally sink and may be dispersed by currents and waves (perhaps aided by air bubbles) and the feet or gut of birds.
Methods of dispersal:
|Reproduction References||Phillips & Menez, 1988, Davison & Hughes, 1998, Hartog den, 1970, Marta et al., 1996, Nacken & Reise, 2000, Dawes & Guiry, 1992, Hughes et al., 2000, Holt et al., 1997, Churchill et al., 1985, Fishman & Orth, 1996, Olesen & Sand-Jensen, 1993, Hootsmans et al., 1987,|