sulfides by supplying enough oxygen to the roots. However, deoxygenation causes the seagrass to be unable to supply this oxygen, thus killing it off. Deoxygenation reduces the diversity of organisms inhabiting seagrass beds by eliminating species that cannot tolerate the low oxygen conditions. Indirectly, the loss and degradation of seagrass threatens numerous species that rely on seagrass for either shelter or food. The loss of seagrass also effects the physical characteristics and resilience of seagrass ecosystems. Seagrass beds provide nursery grounds and habitat to many harvested commercial, recreational, and subsistence fish and shellfish. In many tropical regions, local people are dependent on seagrass associated fisheries as a source of food and income. Diminishing meadows The storage of carbon is an essential ecosystem service as we move into a period of elevated atmospheric carbon levels. However, some climate change models suggest that some seagrasses will go extinct – Posidonia oceanica is expected to go extinct, or nearly so, by 2050. The UNESCO World Heritage Site around the Balearic islands of Mallorca and Formentera includes about of Posidonia oceanica, which has global significance because of the amount of carbon dioxide it absorbs. However, the meadows are being threatened by rising temperatures, which slows down its growth, as well as damage from anchors. Restoration Using propagules Seagrass propagules are materials that help propagate seagrass. Seagrasses pollinate by hydrophily, that is, by dispersing in the water. Sexually and asexually produced propagules are important for this dispersal. Species from the genera Amphibolis and Thalassodendron produce viviparous seedlings. Most others produce seeds, although their characteristics vary widely; some species produce seeds or fruit that are positively buoyant and have potential for long-distance dispersal (e.g., Enhalus, Posidonia, and Thalassia). Others produce seeds that are negatively buoyant with limited dispersal potential (e.g., Zostera and Halophila). although long-distance dispersal can still occur via transport of detached fragments carrying spathes (modified leaves which enclose the flower cluster); e.g., Zostera spp. Nearly all species are also capable of asexual reproduction through rhizome elongation or the production of asexual fragments (e.g., rhizome fragments, pseudoviviparous plantlets). Sexually derived propagules of some species lack the ability to be dormant (e.g., Amphibolis and Posidonia), while others can remain dormant for long periods. These differences in biology and ecology of propagules strongly influence patterns of recruitment and dispersal, and the way they can be used effectively in restoration. Seagrass restoration has primarily involved using asexual material