Zostera novazelandica Setchell is a species of seagrass in the family Zosteraceae found on the shores of New Zealand.
[6][7][8] The species has long, narrow blade like leaves, and a rhizome root structure submerged below the ground.
[7] Zostera novazelandica have elongated, olive-green leaves (50 cm long and 2mm in width) consisting of three longitudinal veins.
[10] The flowers and fruits sit with the leaf blades and are easily located, but inconspicuous and small in size.
[10] The genus of Zostera is found worldwide on the coastlines of Australia, south-east Asia, southern Africa and northern hemisphere countries.
[6] Therefore, where this merge of species is accepted, the seagrass can then be found in Northeastern and Southeastern Australia as well as Papua New Guinea, in addition to New Zealand.
[5][6][9] The New Zealand seagrass establishes in large meadows or small patches in intertidal beds or estuaries.
[8] This is evident in both the increased reproductive and vegetative growth in low salinity waters and its abundance in brackish estuaries.
[12] Once the seedlings are germinated the shoots begin to flower in the spring and immature inflorescence can be observed during late October in all parts of the low and mid tidal zones.
Seed recruitment occurs at very low levels or may even be episodic making the species rely on vegetative growth for survival.
[10][14] Photosynthesis is "the process by which green plants and some other organisms use sunlight to synthesize nutrients from carbon dioxide and water.
The species can recover from loss of photosynthetic tissue, because a significant portion of its total biomass rests below ground.
[12] Zostera novazelandica occurs in soft-sediment seafloors, "sandy mud" or rocky platform reefs.
[6][13] It is a small crab, which burrows in 63% of patches on average and feeds on the blades, basal sheaths, rhizomes and roots.
The overall effect is that the blades are drastically reduced and patches are more vulnerable to possible invasion of crabs, which would result in severe erosion of the plant.
[13] The decline in the New Zealand seagrass species is not only due to natural causes including predation and parasitism, but instead by anthropogenic stressors such as eutrophication, climate change and aquaculture.
[16] These threats include residential and commercial development on shores and pollution, such as agricultural and forestry leaving liquid waste and increasing nutrient loads.
[6] It is believed that there were widespread meadows of Zostera novazelandica in the 19th century, because of the historical accounts made by European naturalists.
For example, Leonard Cockayne (1855-1934) explained that the seagrass was "extremely common in shallow estuaries" and that it "covers the muddy floor...for many square yards at a time.
[18] For example, the New Zealand snapper, an important large fish for commercial and recreational purposes, relies on seagrass such as Zostera novazelandica as a nursery for the first year of their lives.