BIOTIC Species Information for Zostera noltii
|Researched by||Dr Harvey Tyler-Walters||Data supplied by||MarLIN|
|Refereed by||Dr Leigh Jones|
|Typical food types||Not relevant||Habit||Attached|
|Bioturbator||Not relevant||Flexibility||High (>45 degrees)|
|Height||Growth Rate||See additional text|
|Adult dispersal potential||10-100m||Dependency||Independent|
|General Biology Additional Information||Growth
Growth in seagrasses is generally limited by light and affected by temperature (Philliparts, 1995a & b; Marta et al., 1996). Zostera noltii is more tolerant of high light intensities, available at low tide, than Zostera marina, presumably an adaptation to life higher on the shore and the more turbid environment of intertidal flats (Vermaat et al., 1996; Davison & Hughes, 1998). New leaves appear in spring and eelgrass meadows develop over intertidal flats in summer, due to vegetative growth. Increase in shoot density resulting from continuous branching of the rhizome (Vermaat & Verhagen, 1996). A shoot density of 1000-23000 /m² was reported in the Zandkreek estuary, Netherlands (Vermaat & Verhagen, 1996). Leaf growth stops in September/October and leaves are shed although Zostera noltii keeps its leaves longer than Zostera marina in winter. In the intertidal the combined action of grazing and wave action causes leaves to be lost over winter, and the plant reduced to its rhizomes within the sediment. For example, Nacken & Reise (2000) reported that 50% of leaves fell off while the rest were taken by birds (see importance) in the Wadden Sea. In the following season, regrowth occurs from the remaining rhizomes.
The rhizome of Zostera noltii is thinner than that of the longer lived Zostera marina and its growth is rapid and ephemeral in nature, taking advantage of seasonal increases in light and nutrients rather than metabolites stored in the rhizome (Marta et al., 1996; Dawes & Guiry, 1992). Marta et al. (1996) reported shoot growth rates of ca.0.2 cm/day (winter minimum) to ca. 0.8-0.9 cm/day (summer maximum) in the Mediterranean (with winter temperature of 12 °C and summer maximum temperature of 23.2 °C). They also stated that the rhizomes were short lived, <1 year, presumably from one growing season to the next, however given the 'life-span' of vegetative clones of Zostera marina, the plants and seagrass bed of Zostera noltii may be much older.Epiphytes
The following algal species have been recorded only from seagrass leaves: Halothrix lumbricalis; Leblondiella densa; Myrionema magnusii; Cladosiphon zosterae; Punctaria crispata and Cladosiphon contortus, which is larger and found primarily on Zostera sp. rhizomes. Other species of algae are host specific for Zostera marina. The parasitic fungus Plasmodiophora bicaudata Feldm. prevented growth form rhizome internodes and gives the diseased plant a tufted appearance (den Hartog, 1970).
|Biology References||Phillips & Menez, 1988, Davison & Hughes, 1998, Hartog den, 1970, Vermaat et al., 1996, Marta et al., 1996, Nacken & Reise, 2000, Dawes & Guiry, 1992, Philippart, 1995(a), Philippart, 1995(b), Philippart, 1994(a), Holt et al., 1997, Philippart, 1994(b), Vermaat & Verhagen, 1996, Tubbs & Tubbs, 1982, Tubbs & Tubbs, 1983, Plus et al., 2001,|