Thanks to contributions from many, many Seagrass_Forum subscribers, I have compiled a list of uses to which seagrasses have been put by humans ... seagrasses are wonderful plants, by all accounts; something of which we are all well aware, of course!

This is a document under construction: if you have any further suggestions of seagrass uses (preferably with references) please send them to me for inclusion.

Insulation:
Dried seagrass material was commonly used as housing insulation, until well into this century. Its thermal and sound-proofing properties derived largely from the air spaces which occur in mats of seagrass material. One of the major beneficial properties of seagrass as insulation was that it was non-flammable, because of its high silicon content. A popular form of insulation in the United States was something called a Cabot's quilt, named after its inventor. This was a mat of dried seagrass material, i nserted into the walls of houses. The material was also used to sound-proof radio studios in the USA and the UK.

Refs: Cabot (1986); Thomas (1961); Hurley (1990)

Roofing thatch:
Seagrass material was popularly used to thatch roofs in rural coastal areas in Europe and the UK. Its use dates from the seventeenth century (and possibly before), and was used as a substitute for straw. The major advantages of seagrass were that it was slow to rot, and was flea-proof! Presumably its poor combustion properties were also an advantage.

Refs: Urquhart (1824); Ostenfeld (1908); Sloet tot Oldhuis (1855); Martinet (1782); Oudemans et al. (1870)

Binding soil:
Seagrass material was extensively used to bind clay and soil in ambankments; for example, in the dikes of the Netherlands. This use has found a translation into modern times, with seagrass drift being used to produce a mulch applied to sand dunes to help with stabilization. It appears to form an erosion resistant mat, suitable for seed germination in sand dune rehabilitation programmes, and has been used in Australia; presumably similar trials have been conducted elsewhere.

Refs: den Hartog (1970); Martinet (1782); Sloet tot Oldhuis (1855); Capps (1977); Walker (1977); Stewart & Mills (1975); Hurley (1990)

Stuffing and packaging:
Zostera marina has found use as a substitute for horse hair in Europe and the USA, as a material for stuffing pillows, mattresses and upholstery. The crab industry in Chesapeake Bay used seagrass as a packing material for exporting crabs from the region. Seagrass fibre was used to fill leaks in ships hulls in the seventeenth century.

Refs: Ostenfeld (1908); Urquhart (1824); Tubbs (1995); Hurley (1990); Sloet tot Oldhuis (1855); Martinet (1782); Oudemans et al. (1870)

Manure, stock feed supplement, minerals:
Several references document the use of seagrass as a manure, although this is probably more for the algae and other marine organisms entangled within the seagrass mat, than the seagrass itself. Posidonia oceanica, when mixed with lime and phosphates, was used in Mediterranean countries as a meal for feeding poultry. This was also experimented with in South Australia, although only on a limited basis. Washed up seagrass wrack is commercially used to make garden mulch, although there is speculatio n that this is largely for bulk.

Various workers over the past few decades have studied the mineral composition of seagrasses, and concluded that, while considerable quantities of minerals such as Boron occur in seagrass material, it is not commercially viable to extract. There are suggestions that in Denmark seagrass material may have been burned as a source of salt, soda minerals or simply for warmth. Old reports also exist about seagrass as a relief for rheumatism.

A new project is about to be put into production in Mt Gambier South Australia by Van Schaiks Bio Gro www.biogro.com.au. The project involves utilizing Posidonia australis washed up on the Kingston Township beach. The material is harvested at the end of winter (some thousands of tonnes), it is semi decomposed in windrows, sieved to remove stalk material,and processed at moderate temperature and alkalinity to produce a liquid plant nutrient very similar in mineral and amino acids etc. to other plant nutrients sourced from seaweed. It is combined with humic and fulvic acids being produced from local peat sources. Green house trials conducted over the past year have produced results consistantly better than those obtained by using seaweed based extracts. Products will go on to the Australian and International markets in early 2006. (Information provided by BioGro.)

Refs: Ostenfeld (1908); Urquhart (1824); Waters (1965); Stewart & Mills (1975); Sloet tot Oldhuis (1855); Martinet (1782); Oudemans et al. (1870)

Weaving, fibre products, paper-making:
Japanese fishers used Phyllospadix iwatensis as a material for making wet weather gear up to the 1930s, when rubber became popular. There are unconfirmed reports of seagrass fibre being used for basket-weaving from the east coast of the USA, although other aquatic (freshwater) vegetation may actually be used in this instance). Seagrass fibre is used to make "coir" mats and rugs sold in Australia. During the Second World War seagrass fibre was used as a substitute for cotton in the manufacture of nitrocellulose in Germany. Experiments were carried out in England, on the use of seagrass fibre for paper making.

Refs: McRoy & Helfferich (1980)


References:

Bremer, J.T. (ca. 1979) Wierwinning en wierhandel (ca.1850-1930).
Wiringerplant. Pirola :136-149

Cabot, S. (1986) Memories of Cabot's Quilt. Yankee November 118-204

Capps, P.G. (1977) Use of seaweed as hydromulch for revegetation. South Australian Coast Protection Board, Amdel Report No. 1182. Australian Mineral Development Laboratories, Frewville,South Australia.

Hurley, L.M. (1990) "U.S. Fish and Wildlife Service Field Guide to the Submerged Aquatic Vegetation of Chesapeake Bay." Chesapeake Bay Estuary Program, Annapolis, MD 21401. 51pp.

Martinet, J.F. (1782) Verhandeling over het wier der Zuiderzee. Verhandelingen Hollandsche Maatschappij der Wetenschappen 20:54-129+plates I-VI

McRoy, C. P. & Helfferich, C. (1980) Applied Aspects of Seagrasses. In: "Handbook of Seagrass Biology; An Ecosystem Perspective", Phillips, R. C. and C. McRoy, C.P. (eds). Garland STPM Press, New York.

Ostenfeld, C.H. (1908) On the Ecology and Distribution of the Grass-Wrack
(Zostera marina) in Danish Waters. Rep. Dan. Biol. Stn. 16:1-62

Oudemans, C.A.J.A.; Conrad, J.F.W.; Maats, P.; Bouricius, L.J. (1870) Verslag der
Staatscommissie inzake de wiermaayerij. Verslag aan de Koning over de Openbare Werken in het Jaar 1869. Van Weelden en Mingelen, Den Haag, p 199-231

Sloet tot Oldhuis, B.W.A.E. (1855) Het zeewier. Tijdschr v Staatshuishoudkunde en Statistiek 11:192-210

Stewart, C.M.; Mills, J.A. (1975) Some notes on the chemistry and utilization of Posidonia australis. Notes compiled by C.M Stewart and J.A. Mills, CSIRO Division of Chemical Technology, South Melbourne.

Thomas, F.G.S. (1961) The King Holds Hayling (Pelham, Havant),
cited in Tubbs, C.R. 1995 The Meadows in the Sea British Wildlife 6(6):351-355

Urquhart, J. T. (1824) On the Preparation of the Zostera or seagrass in Orkney. Prize essays and transaction of the Highland Society of Scotland, 6:590

Walker, D.J. (1977) Report of the seaweed problem on Taperoo Beach. South Australian Coast Protection Board Report.

Waters, B.H.J. (1965) Utilization of South Australian seaweeds. South Australian Government Department of Mines, Amdel Report No. 426. Australian Mineral Development Laboratories, Frewville, South Australia.