- a single-layered membrane or sac-like network of several thousand cells
- free-ﬂoating or secondarily attached
- reaching over 50cm long
- meshes clearly visible in large colonies
- cylindrical to oblong-oval, up to 15mm long
- 2-4 adjacent cells connected by their edges and forming 5-6-sided meshes
- clogs waterways and irrigation ditches,
- taints potable water,
- causes economic losses to trout ﬁsheries,
- smothers aquatic plants and fauna
- adversely impacts boating, fishing, swimming and tourism
Cell contents cleave to produce unicellular, biflagellate zoospores or gametes. Unlike the zoospores the gametes are not released but lose their flagella and produce miniature colonies within the mother cell wall.The similar sized gametes fuse to form a zygote and these become thick-walled and angular. After a rest period each produces 2-5 zoospores each of which becomes an enlarged polygonal cell whose contents divide into flagellated cells which produce a new miniature colony.The miniature nets are released by gelatinisation of the cell wall.
Free-floating mats of often accumulate in vast quantity in sheltered bays along the downwind shores of ponds and lakes. These mats frequently blanket the surface and are capable of undergoing sudden changes in buoyancy and therefore disappear only to quickly reappear especially during calmer periods.
Water net frequently forms extensive surface and subsurface mats in ponds and lakes and in the marginal shallows of rivers during low flow conditions in the summer months.Conspicuous seasonal blanketing growths in:
- Drainage channels
- Patches of damp ground
- water movement
The water net is a serious nuisance alga because it clogs waterways and irrigation ditches, taints potable water, causes economic losses to trout ﬁsheries, smothers aquatic plants and fauna and has an adverse impact upon boating, fishing, swimming and tourism.Shallow water mats
- smoother beds of aquatic macrophytes causing their collapse and decay.
- reduce the aesthetic appeal of waters
- interfere with recreational activities by
- blocking marinas
- hampering intakes of boat engines
- swimming and fishing
Some studies have demonstrated water net having a beneficial impact on invertebrates.
Climate change response
The rapid spread of the water net in the British Isles is believed to be a climate change response relating to elevated and extended summer water temperatures and low river flows.The sudden appearance of small (>2cm long), cylindrical colonies in May and June on the surface of a lake near Helston in Cornwall (UK) was associated with the water reaching 15°C. Such colonies increased in size several thousand fold within a few days and gave rise to entangled, cylindrical-shaped colonies blanketing the surface.
Molecular Biology and Genetics
Barcode data: Hydrodictyon reticulatum
Statistics of barcoding coverage: Hydrodictyon reticulatum
Public Records: 7
Specimens with Barcodes: 7
Species With Barcodes: 1
To request an improvement, please leave a comment on the page. Thank you!