Lecture 10 - Sea Grass systems

Question 1

give some details about sea grass systems

Answer 1

These are made up of submerged aquatic vegitation, angiosperms! true flowering plants but no grasses, super high production, low diversity due to narrow range of habitats. These are fragile and fast declining :(

Question 2

Name the three med to tropical families of sea grasses

Answer 2

Posidoniaceae
Cymodoceaceae
Hydrocharitaceae

Question 3

Name the one temperate to med family of sea grass

Answer 3

zosteraceae

Question 4

Name the two tropical families of sea grass

Answer 4

Ruppiaceae

Zannichelliaceae

Question 5

Examples of sea grass species

Answer 5

Eelgrass (Zostera spp.) short growth, they have a rhizome systems which stabilises sediment and allows for growth

Question 6

Tell me about paddle grass (Halophila decipiens)

Answer 6

Different shape, very short with a large surface area for photosynto grows in faster currents

Question 7

Give the 7 points about sea grass ecology

Answer 7

> Strap-like flattened leaves - leaf blades, extensive root and rhizome systems just like grass
No stomata
Thin cuticle with waxy layer
Arenchyma tissue for gas exchange and buoyancy
Lacunae - continuous channels for gas to roots
Root hairs (nutrient uptake)
Halophylic - salt tolerant

Question 8

what is the typical temperature range for sea grass systems

Answer 8

0 to 36oC

Question 9

typical salinity range for seagrasses

Answer 9

0 - 90

Question 10

Explain the movement of oxygen in sea grasses

Answer 10

o2 transported to rhizomes and roots of sea grasses during periods of light when photosynto releases o2 into arenchyma, this then forms an oxidised zone around the roots by night 02 transport ceases and water becomes the source of o2

Question 11

What are the three types of reproduction in sea grass systems

Answer 11

Sexual (classic)
Asexual (through rhizome growth)
Pollination

Question 12

Explain pollination and exceptions

Answer 12

Hydrophillic pollination occurs although there are some exceptions

a) Pollen above water surface
b) on water surface
c) beneath water surface

Question 13

What are Epiphytes

Answer 13

These are a form of algae “epiphytic algea” which cuts down light onto the sea grasses as it grows on them, Some grasses have adapted to grow even when 90% of leaf blade is covered by epiphytic algea.

Question 14

How many fauna are associated with sea grass systems and some key fishys

Answer 14

4000 fish and 50 million invertebrates in a single acre of sea bed grass key species include:
Sea turtles
Parrotfish
Sureonfish
Sea Urchins
Queen conch
Manatees and Dungongs

Question 15

What are potential threats and issues for sea grass systems

Answer 15

Storm damage
Excessive raxing (root and rhizome gets distrubed)
Dredging
Boat damage
Pollution
Wasting disease