Seagrasses
Seagrasses form important ecosystems in all coastal areas of the world except Antarctica. Seagrass ecosystems are highly productive, and support high levels of biodiversity. They provide nursery habitat for small fishes and invertebrates, and food for a wide variety of animals.  They also stabilize sediments, and help maintain water clarity by trapping sediment particles.

Biscayne National Park contains extensive seagrass beds throughout the bay and on the reef tract. Most of the Biscayne’s recreationally and commercially important fishes, crustaceans, and shellfish spend a portion of their lives in seagrass habitat. Three species of seagrasses are commonly found in the Park.

Turtle grass (Thalassia testudinum) has wide leaf blades and a deep root structure, and forms most of the large, lush seagrass meadows found in the park. Sea turtles and some fish like parrotfish feed on turtle grass.

Manatee grass (Syringodium filiforme) is recognized easily because of its cylindrical leaves. Like its name suggests, manatees feed on this type of seagrass.

Shoal grass, Halodule wrightii, is an early colonizer of disturbed areas and usually grows in very shallow water. The leaves are generally smaller than the other two species.

Two other species of seagrasses have been documented in Biscayne National Park: star grass (Halophila englemanni) and paddle grass (Halophila decipiens).

 

In addition to seagrass species, numerous species of macroalgae can be found in marine habitats throughout Biscayne National Park. Macroalgal species are often termed 'marine plants', however these species are non-vascular precursors to true plants. Although not exhaustive, the following list presents some of the more commonly observed species of macroalgae. Very few species of marine macroalgae have widely recognized common names, so only scientific names are provided.

Acanthophora spicifera

Acetabularia calyculus

Acetabularia crenulata

Acetabularia schenckii

Amphiroa compressa

Anadyomene stellata

Batophora occidentalis

Batophora oerstedii

Caulerpa lanuginosa

Caulerpa mexicana

Caulerpa paspaloides

Caulerpa prolifera

Caulerpa racemosa

Caulerpa sertularioides

Chondria baileyana

Cladosiphon occidentalis

Digenea simplex

Halimeda copiosa

Halimeda goreaui

Halimeda incrassata

Halimeda monile

Halimeda tuna

Laurencia gemmifera

Laurencia intricata

Laurencia poitei

Lobophora variegata

Neogoniolithon spectabile

Neomeris annulata

Penicillus capitatus

Penicillus dumetosus

Penicillus pyriformis

Porolithon pachydermum

Rhipocephalus phoenix

Sargassum fluitans

Sargassum natans

Sargassum pteropleuron

Spyridia filamentosa

Stypopodium zonale

Udotea conglutinata

Udotea dixonii

Udotea flabellum

Ventricaria ventricosa

Wrangelia penicillata

Seagrass Epiphytes

Seagrass leaves are colonized by tiny organisms called epiphytes. Seagrass epiphytes are extremely diverse and include microalgae, macroalgae, bacteria, byrozoans, fungi, sponges, hydroids, crustaceans, and molluscs. Algal epiphytes are photosyntetic and contribute to the primary production of the ecosystem. Most of the larger fish and invertebrate consumers in seagrass ecosystem feed on seagrass epiphytes. Few organisms feed directly on seagrass leaves.