Manatee Grass

Manatee Grass (Syringodium filiforme) is a native Florida seagrass introduced to miniBIOTA's Seagrass Meadow on March 27, 2026 as part of a beach collection that also brought in turtle grass, green feather alga, megafern feather alga, and a small mud crab. It was added deliberately as a producer diversity species to complement established seagrasses with a different growth form and leaf shedding pattern. Species identity is Confirmed from the introduction record. Population status is Uncertain; establishment and persistence since introduction are unresolved as of June 10, 2026.

Range and Florida Relevance

Syringodium filiforme is native to the Caribbean Sea, Gulf of Mexico, and the Atlantic coast from Florida south to Brazil. In Florida, it is one of the three dominant shallow-water seagrasses, alongside turtle grass (Thalassia testudinum) and shoal grass (Halodule wrightii), that form the foundation of Florida's coastal seagrass ecosystem. Manatee grass is common in Florida Bay, the Florida Keys, the Gulf Coast, and the Indian River Lagoon. It grows in water depths from less than one meter to about six meters, depending on light availability, and is frequently found growing intermixed with turtle grass in mixed seagrass beds.

Structure and Growth

Manatee grass is recognizable by its cylindrical (round cross-section) leaf blades, which distinguish it from all other common Florida seagrasses, which have flat blades. The cylindrical leaves resemble green spaghetti, hence the alternate name "spaghetti grass", and are typically 10 to 30 centimeters long. The plant grows from horizontal rhizomes buried in the substrate; upright shoots bearing leaf blades emerge from the rhizomes at regular intervals. Roots anchor the rhizome system into the sediment and absorb water and dissolved nutrients.

In miniBIOTA, the species would need to establish root and rhizome contact with the Seagrass Meadow substrate. Whether the introduced material has rooted and begun growing is unconfirmed as of June 2026.

Photosynthesis and Nutrition

Syringodium filiforme is a photosynthetic producer. It requires adequate light penetration to the substrate, carbon dioxide dissolved in the water, and dissolved inorganic nutrients. It is moderately sensitive to light reduction; turbid or shaded water limits growth. It competes for light with epiphytic algae that colonize its leaf surfaces, and with other producers in the seagrass community.

Epiphytes

Like all seagrasses, manatee grass supports a community of epiphytic algae, bacteria, and small invertebrates on its leaf surfaces. These epiphytes are an important food source for small grazers (amphipods, isopods, shrimp) that scrape them from the leaf surface. In miniBIOTA, if the grass establishes, its leaf surfaces would become a grazing surface for the Seagrass Meadow's invertebrate community.

Leaf Shedding and Detritus

Seagrass leaves are periodically shed and replaced. Shed manatee grass leaves enter the detrital food web, where they are colonized by bacteria and fungi and processed by detritivores. The distinct leaf morphology and shedding timing of manatee grass can contribute a different detritus input pattern than other seagrasses in the same system.

Reproduction

Syringodium filiforme reproduces primarily through vegetative spread of the horizontal rhizome system. New shoots grow from the rhizome as it extends laterally through the substrate. The species also produces flowers and seeds; pollination is hydrophilous (through the water column). Seeds settle to the substrate and can establish new rhizome systems. In a closed aquarium system, vegetative rhizome spread is the most relevant growth mechanism. No reproductive activity has been observed in miniBIOTA.

Tolerance Ranges

Syringodium filiforme prefers warm subtropical to tropical water temperatures, consistent with its Florida and Caribbean range. It is sensitive to prolonged cold stress and grows best above approximately 15 degrees Celsius. It tolerates salinity from approximately 15 to 40 parts per thousand but grows best in the 25 to 35 ppt range. It requires moderate to high light levels and is sensitive to sediment smothering and chronic turbidity. It does not tolerate anoxic substrate well for extended periods.

Manatee Grass is a photosynthetic seagrass producer that contributes to primary production in the Seagrass Meadow. By growing upward from the substrate, it creates vertical structure in the water column, providing surfaces for epiphytic communities that support small invertebrate grazers. Shed leaves enter the detrital food web and are processed by detritivores. The rhizome network stabilizes substrate and contributes organic matter to the sediment layer.

In natural settings, manatee grass is a primary food source for the West Indian manatee (Trichechus manatus), which gives the plant its name, and is also grazed by sea turtles, sea urchins, some fish, and waterfowl. In miniBIOTA's closed saltwater system, direct manatee and turtle grazing is not present; grazing pressure would come from any invertebrate herbivores in the Seagrass Meadow. No predation or grazing of this species has been observed in miniBIOTA.

The addition of manatee grass as a producer alongside turtle grass (introduced the same day) and any established shoal grass creates a multi-species seagrass community with complementary growth forms and leaf shedding patterns, which diversifies the primary production and detrital inputs to the Seagrass Meadow.

Introduction

Manatee Grass was introduced to miniBIOTA on March 27, 2026 as part of a beach collection that included turtle grass (Thalassia testudinum), green feather alga (Caulerpa taxifolia), megafern feather alga (Caulerpa ashmeadii), a small mud crab, and a possible unidentified amphipod species. All material was collected from a Florida beach and introduced to the Seagrass Meadow on the same day. Manatee grass was identified by scientific name in the collection record.