What is Seagrass?

Seagrass is an unusual example of an entirely aquatic marine flowering plant. It grows in large meadows in areas of shallow water, providing a habitat to numerous species from all phyla, including free-living macroalgae and microalgae, bristle worms, mollusks, nematodes, and many fish, especially white-spotted puffers. Its green meadows are either monospecific (containing one species) or multispecific (many). Temperate meadows are more likely to be dominated by one or a few species, while tropical meadows, like those in the Philippines, may have as many as 13 or more. It is estimated that there are about 60 species of seagrass worldwide.

Like other grasses, to which they are not closely related, seagrasses are monocots, the smaller and simpler group of flowering plants. Seagrass is a fairly recent evolutionary innovation, having evolved from saltwater-tolerant land plants, especially mangroves, which are believed to be its immediate ancestor. Seagrass didn't likely exist prior to about 60 million years ago, shortly after the extinction of the dinosaurs, but since then, it has spread to most of the temperate and tropical coasts of the world. Oddly, seagrass is considered to be part of the "land plants," because it evolved from them and has much more in common with land plants than algae, from which land plants evolved about 450 million years ago.

Like the true grasses, seagrass has relatively little nutritional content, meaning that only specially adapted animals can eat it, but recent findings have determined that seagrass is more commonly consumed than once thought. In fact, it likely forms a foundation of the food chain for hundreds of species. Dugongs, manatees, swans, fish, geese, sea urchins and crabs have all been observed eating seagrass. Even if a species of animal can't consume seagrass directly, it may be able to consume other animals that feed upon the seagrass.

Seagrass is an example of a group called "ecosystem engineers," like coral, because they significantly modify their surrounding environment, attract certain species, and discourage others. The seagrass slows down water currents, encouraging the buildup of sedimentation, which can serve as a hiding spot for small bottom-dwelling creatures. Seagrass has an extraordinary rate of primary production, meaning that it converts sunlight and nutrients into biomass more effectively than most other marine plants.

Seagrass refers to about 60 species of marine flowering plants that form dense underwater meadows in shallow, salty, and brackish waters worldwide. These unique ecosystems are found along coastlines in every continent except Antarctica and play a crucial role in marine biodiversity, according to the World Wildlife Fund.

Seagrass meadows are biodiversity hotspots, providing habitat and nursery grounds for numerous marine species. They stabilize the seabed, prevent erosion, and improve water clarity by trapping fine sediments and particles. Seagrasses also sequester carbon at a rate 35 times faster than tropical rainforests, making them important in combating climate change, as reported by the International Union for Conservation of Nature.

Historically, seagrass has been used for a variety of purposes, including insulation, mattress stuffing, and even roofing material. Today, its ecological services are highly valued, such as supporting fisheries and protecting coastlines. Seagrass meadows also have the potential for bioenergy production and are used in traditional medicines in some cultures.

No, seagrass and seaweed are quite different. Seagrass is a true plant with roots, stems, leaves, flowers, and seeds, while seaweed is a type of algae without these structures. Seagrasses perform photosynthesis and reproduce sexually, whereas seaweeds can reproduce through simple cell division and spore formation.

Seagrass meadows are under threat from coastal development, pollution, sedimentation, climate change, and destructive fishing practices. The United Nations Environment Programme estimates that we are losing seagrass meadows at a rate of about 7% per year since 1990, which is alarming for the health of marine ecosystems.

Protecting seagrass involves reducing water pollution, managing coastal development responsibly, and implementing marine protected areas. Restoration projects are also crucial, where seagrass is replanted in areas where it has been lost. Public education and awareness campaigns can help garner support for conservation efforts, as the health of seagrass meadows is integral to the overall health of our oceans.