Home > Uncategorized > Seagrass Species Observed in Watamu Marine National Park

Seagrass beds support a large variety of associated flora and fauna. A vital part of the marine ecosystem due to their productivity levels, seagrass provides ecological roles and ecosystem services such as carbon storage, feeding grounds for coral reef organisms, habitat and nursery areas for numerous vertebrate and invertebrate species. The vast biodiversity and sensitivity to changes in water quality inherent in seagrass communities make seagrass an important species to help determine the overall health of an ecosystem.

Out of the 12 species of seagrass recorded in Kenya, 11 have been found in Watamu Marine National Park. One of seagrass species, Zostera capensis, is listed as Vulnerable in the IUCN Red List with its population decreasing. The seagrasses are the most dominant component of the park covering nearly 40% of the benthos (Cowburn et al., 2018). This shows how the park is
important in the conservation of these species.

This seagrass identification guide was developed in order to help the Kenya Wildlife Service in the management of the park especially during the monitoring of the park. The guide can also be used by citizen scientists and researchers who want to identify seagrass species found in Watamu Marine National Park. Our hope is that this guide facilitates much work to benefit the park and the people of Watamu who depend upon it.
Eric Thuranira, A Rocha Kenya Marine Intern

Acknowledgements
I thank Kenya Wildlife Service (KWS) for permission to carry out this work within the protected area. Special gratitude to Dr.Robert Sluka, Dr.Colin Jackson and Dr Dorothea Seeger for reviewing the guide and volunteers (Leah, Michael and Kayla) who helped during fieldwork.

Cymodocea rotundata
Rhizomes: Pale pink in color; 1 shoot/node; 1-4 cm internodes
Sheath: 2-4 cm in length; Shaggy
Leaf Length: 8-15 cm
Leaf Width: 3-4 mm
Leaf Edge: Smooth; slightly serrated in young leaves
Leaf Shape: Rounded
Veins: 9-15
Petiole: N/A
Habitat: Soft substrata and coral sand in lower intertidal

Cymodocea serrulata
Rhizomes: Pale in color; regularly spaced shoots; 2 roots/node
Sheath: 2-4 cm in length; scar stem
Leaf Length: 8-15 cm
Leaf Width: 3-4 mm
Leaf Edge: Serrated in old and young plants
Leaf Shape: Rounded
Veins: 9-15
Petiole: N/A
Habitat: Soft substrata and coral sand in lower intertidal

Enhalus acoroides
Rhizomes: Short internodes, densely covered with persistent fibrous remains of leaf sheaths
Sheath: 15-30 mm in length
Leaf Length: 30 -150 cm
Leaf Width: 2cm
Leaf Edge: Smooth
Leaf Shape: Rounded or flattened tips, outer blades float on surface at low tide.
Veins: Parallel
Petiole: N/A
Habitat: Sheltered coasts on sandy and gravelly bottoms in mangroves channels.
© F.T Short/UNH

Halodule uninervis
Rhizomes: Reddish pale in color; 0.5-4 cm internodes; 1-6 leaves/node
Sheath: 1-3.5 cm in length
Leaf Length: 6-15 cm
Leaf Diameter: 1-2 mm
Leaf Edge: Smooth
Leaf Shape: Narrow; strap-shaped with tridentate tip
Veins: 3 parallel veins; conspicuous central vein bluntly protrudes at tip
Petiole: N/A
Habitat: Soft-bottomed intertidal and mangrove areas

Halodule wrightii
Rhizomes: Long, white
Sheath: 15-30 mm in length
Leaf Length: 30 cm
Leaf Width: Less than 1mm
Leaf Edge: Smooth
Leaf Shape: Apex concave or bidentate
Veins: Parallel
Petiole: N/A
Habitat: Sandy and muddy substrates
© Brenda Bowling

Halophila ovalis
Rhizome: Pale cream in color; 2 mm wide; 1 root/node
Leaf length: 4 cm
Leaf Width: 1 cm
Leaf Edge: Non-serrate; smooth
Leaf Shape: Oval-shaped with rounded tip
Veins: 8-25 pairs of cross-veins
Petiole: Prominent; up to 5 cm
Habitat: Subtidal to 15 m; muddy intertidal

Halophila stipulacea
Rhizomes: Pale; 1 root/node; 0.5-2 mm internodes
Leaf Length: 3-6 cm
Leaf Width: 3-7 mm
Leaf Edge: Slightly serrated
Leaf Shape: Linear; strap-shaped with rounded tip
Cross Veins: Visible ascending cross-veins
Petiole: Inconspicuous with pair of transparent scales up to half-length of petiole
Habitat: Subtidal

Syringodium isoetifilium
Rhizomes: Pink-orange in color; ~3 roots/node; 1.5-3.5 cm internodes
Sheath: 2-4 cm in length
Leaf Length: 15-20 cm with a maximum of 45 cm
Leaf Diameter: 2 mm
Leaf Edge: Smooth
Leaf Shape: Cylindrical
Veins: Inconspicuous
Petiole: N/A
Habitat: Sandy and muddy substrates; sublittoral fringe to shallow sublittoral

Thalassia hemprichii
Rhizomes: Pale yellow, 3-5mm thick with internodes 4-7mm long.
Sheath: Commonly present at base of green leaves.
Leaf Length: 10-30cm
Leaf Width: 5-8mm
Leaf Edge: Leaf apex not serrulate
Leaf Shape: Round at the tip
Veins: Parallel
Petiole: N/A
Habitat: Sheltered coasts on sandy and rubbly reef platforms.

Thallassodendron ciliatum
Rhizomes: Cream in color; roots and stems at every fourth internode; 1.5-3 cm internodes
Sheath: 15-30 mm in length
Leaf Length: 15 cm
Leaf Width: 6-12 mm
Leaf Edge: Serrated with round tip
Leaf Shape: Palm-like clusters of 3-10 strap-shaped, curved leaves on a long stem
Veins: 8-13 vertical parallel veins
Petiole: N/A
Habitat: Subtidal; lower eulittoral to sublittoral; sandy or rubbly substrates

Zostera capensis
Rhizomes: Yellowish-Red, 0.5-2mm wide with 1-2 roots at each node.
Sheath: Open sheath
Leaf Length: 25cm
Leaf Width: 2.5mm
Leaf Edge: Smooth
Leaf Shape: Leaf apex obtuse or rounded
Veins: More than 5 parallel and translucent veins
Petiole: N/A
Habitat: Muddy and coral substrates in lagoons.
©F.T Short/UNH

References
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Cowburn, B., Musembi, P., Sindorf, V., Kohlmeier, D., Raker, C., Nussbaumer, A., . . . Kamire,
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