Download Seagrass

BIOLOGY OF SEAGRASS
Mujizat Kawaroe
Marine Biology and Biodiversity Laboratory
2007
Email : [email protected]; [email protected]
Seagrasses
• A type of submerged aquatic vegetation have evolved from
terrestrial plants and have become specialized to live in the
marine environment.
• Seagrasses have leaves, roots, conducting tissues, flowers
and seeds, and manufacture their own food via
photosynthesis.
• Seagrasses do not possess the strong, supportive stems and
trunks required to overcome the force of gravity on land.
• Seagrass blades are supported by the natural buoyancy of
water, remaining flexible when exposed to waves and
currents
Seagrass
• Marine plants with the same
basic structure as terrestrial
(land) plants.
• They have tiny flowers and
strap-like or oval leaves.
• They form meadows in
estuaries and shallow coastal
waters with sandy or muddy
bottoms.
• Most closely related to lilies,
they are quite different from
seaweeds, which are algae.
Seagrass vs Alga
• Structurally, seagrasses, like terrestrial
plants, possess specialized tissues that
perform specific tasks within each plant.
Algae are relatively simple and
unspecialized in structure.
• Algae possess only a tough holdfast that
assists in anchoring the plant to a hard
substratum, seagrasses possess true roots
that not only hold plants in place, but also
are specialized for extracting minerals and
other nutrients from the sediment.
Seagrass vs Alga
• All algal cells possess photosynthetic structures capable of
utilizing sunlight to produce chemical energy. In
seagrasses, chloroplasts occur only in leaves, thus
confining photosynthesis to leaves.
• Algae are able to take up minerals and other nutrients
directly from the water column via diffusion. Seagrasses
however, transport minerals and nutrients in xylem and
phloem.
• Algae lack specialized reproductive structures, most
seagrasses have separate sexes and produce flowers and
seeds, with embryos developing inside ovaries.
Seagrass vs Alga
• Seagrasses produce flowers, fruit and seeds —
algae produce spores.
• Seagrasses, have separate roots, leaves and
underground stems called rhizomes. These can
form an extensive network below the surface.
Algae rarely have ‘roots’ below the surface.
• Unlike algae, seagrasses are vascular plants —
they have a network of veins to move nutrients
and dissolved gases around the plant.
How seagrass grows
• Seagrasses need nutrients, often obtained from nearby
mangroves, and good light, which means clear water.
• They cannot grow easily where they dry out at low tide.
• They therefore thrive in shallow coastal waters where
there is shelter (such as a sand bar) from drying winds
and from wave action and strong currents which could
create turbulent muddy water.
• Although normally found in shallow water they can
grow at depths of 32m and have been found in clear
water at 68m
How seagrass survives
• While the roots of seagrasses serve to anchor the plants they are
not necessary for water intake. They share the task of nutrient
collection with the leaves which can absorb food and water
directly from the surrounding water.
• The flowers are very small.
• Water carries the pollen from the male to the separate female
flowers.
• The resulting fruit are often carried some distance from the
parent plant before the seeds are released.
• Flowering, however, is not common for most tropical species
and the spread of seagrasses is largely through vegetative
propagation by the growth and branching of rhizomes.
Seagrass
Seagrass Community
Pickled Syringodium
A taste of
seagrass…
Classic Oatmeal Raisin Cookies
with Enhalus seed flour
Handicrafts from seagrass