Subtidal cylindrical seagrass
Subtidal seagrass meadows dominated by the cylindrical Syringodium isoetifolium.
Disclaimer: Ecosystem type descriptions are based on biophysical attributes identified in Central Queensland through expert advice and supported by scientific literature. Not all ecosystem types are mapped based on current inventory, and many of the ecosystems described here may also occur in other parts of Queensland.
Select from the links below to view related ecosystem type categories
Subtidal seagrass meadows dominated by the cylindrical Syringodium isoetifolium. These ecosystems typically occur as patches in small meadows or interspersed with other seagrasses such as Zostera muelleri subsp. capricorni*, Cymodocea rotundata, Cymodocea serrulata, Enhalus acoroides, Halodule uninervis, Thalassia hemprichii, Halophila spp and/or Thalassodendron ciliatum.
Seagrasses are not a taxonomically unified group, but rather an ecological group that arose through convergent evolution and includes several different families. They are all flowering plants that live underwater and need light to photosynthesise. They also produce seeds. Meadows may include Structural macrobiota such as encrusting algae, erect macrophyte algae, bryozoans, sponges and molluscs (e.g. bivalves, cockles, whelks, razor clam beds), together with mobile invertebrate fauna such as sea cucumbers, crabs (e.g. commercial sand crabs and other portunids) and polychaete worms.
*Revision of Zostera capricorni has resulted in classification to subspecies. In Queensland, Zostera capricorni has been revised to Zostera muelleri subsp. capricorni.
Seagrasses provide a wide range of services, including:
The fisheries value of seagrass habitat as nursery grounds for juvenile commercial fish, prawn, crab and crayfish species in Queensland is well documented. Sea cucumbers may also be collected for commercial aquaculture.
Not only do seagrass provide habitat for fish, but the proximity of seagrass meadows to other ecosystems (mangroves, coral reefs) increases their abundance in these ecosystems.
Structural macrobiota 'Seagrass - cylindrical seagrass)
Seagrass ecosystems vary in Period and Trend (seasonally and from year to year). The species composition, extent and biomass of seagrass meadows can vary seasonally and between years. The extent and biomass of seagrass meadows along the Queensland east coast are typically maximal in late spring and summer, and minimal over winter.
Seagrass meadows grow throughout the world’s coastal waters, with large areas along Queensland’s coastline. Approximately 58 species of seagrass have been recorded across the globe with about 30 recorded in Australian waters and at least 15 in Queensland (SeagrassWatch). Most tropical and sub-tropical species are found in water less than 10 m deep and wide strap seagrasses are typically found in shallow water and the intertidal area (coastal areas and within estuaries).
Most tropical and sub-tropical species are found in water less than 10 metres deep. Of the 13 species identified in north-eastern Queensland all occurred in water depths less than 6 metres below mean sea level (MSL) and only four occurred in water more than 20 metres below MSL. Three general depth zones of seagrass species composition for tropical waters have been observed: a shallow zone less than 6 metres deep with high species diversity, likely to include all species found in a region; a zone between 6 and 11 metres where the most commonly found seagrasses were the pioneering Halodule and Halophila species; and a zone deeper than 11 metres where only species of the genus Halophila were commonly found.
The following relates to distribution of this ecosystem type within the Central Queensland mapping area:
Other relevant attributes include Water clarity, Energy magnitude and Energy source (wave) together with Sediment texture, Freshwater volume and Trace elements. Seagrasses need light to be able to photosynthesise and turbid water inhibits light penetration, thus the Benthic depth that light can penetrate is a major control. Severe storms (cyclones), and/or high rainfall, river discharge and the associated low Water clarity and high concentrations of nutrients and other potential contaminants, and sediment deposition leads to seagrass loss (see SeagrassWatch annual reports for inshore seagrass monitoring in the Great Barrier Reef Marine Park). Trace elements (nutrients N, P), herbicides and other contaminants are known to affect seagrass health and other Structural macrobiota. This includes epiphytic algae and macroalgae which are indicators of high nutrients. Water temperature is also relevant. Marine heatwaves can also negatively impact seagrass meadows.
Mapping represents locations where seagrass has been recorded at some point in time, and therefore locations where seagrass may grow now or in the future providing environmental conditions are suitable (e.g. wave action, Water clarity, Sediment stability, Temperature and Trace elements (the presence of nutrients and other potential contaminants)).
Seagrass - Queensland Government
Seagrass (Case study: Hervey Bay seagrass and dugong) - Queensland Government
Saltmarshes, seagrasses and algae - Department of Agriculture and Fisheries
Seagrasses in Queensland (pamphlet)
Seagrass - Department of Environment and Science
Seagrasses - Australian Institute of Marine Science
A Vulnerability Assessment for the Great Barrier Reef (Seagrass) - Great Barrier Reef Marine Park Authority
Last updated: 19 July 2019
This page should be cited as:
Department of Environment and Science, Queensland (2019) Subtidal cylindrical seagrass, WetlandInfo website, accessed 1 February 2023. Available at: https://wetlandinfo.des.qld.gov.au/wetlands/ecology/aquatic-ecosystems-natural/estuarine-marine/descriptions/51/