1. Synopsis on Seagrass of Egypt, Seagrass Morphology and General Taxonomy Dr. Soha Shabaka Hydrobiology Laboratory National Institute of Oceanography and Fisheries Ministry of State for Scientific Research of Egypt

2. I- Introduction

3. Evolutionary history of seagrasses
　　Seagrasses should posses the following criteria (Arber 1920) :
Adapted to live in a saline medium
Grow when completely submerged
Strong anchoring system
Capacity for hydophilous pollination
Land plants penetrating into the sea and not well developed
Well-adapted seagrasses with some terrestrial characteristics.
Modern seagrasses.

4. What are seagrasses?
Marine plants with the same basic structure as terrestrial (land) plants.
They are quite different from seaweeds.
Algae (Ulva lactuca)
Seagrass

5. Schematic illustration of major human-induced impacts on a tropical seagrass ecosystem. (Duffy J. E. 2006).

6. Seagrass deterioration (Orth et al., 2006)
Extreme events (Hurricanes and Tsunamis)
Global warming
Invasive species
Overgrazing
Algal blooms
Wasting disease
Sediment and nutrients runoff (low water quality)
Commercial fishing operation
Aquaculture

7. General Taxonomy Division: Magnoliophyta (Angiosperms)
Class: Liliopsida (Monocotyledonus)
Seagrasses are grouped into 12 genera, to which belong about 60 species.
Families:
Zosteraceae (Zostera, Heterozostera, Phyllospadix),
Posidoniaceae (Posidonia),
Cymodoceaceae (Cymodocea, Halodule, Thalassodendron, Syringodium, Amphibolis)
Hydrocharitaceae (Halophila, Thalassia, Enhalus).
Ruppiaceae
Potamogetonaceae

8. II. Seagrass of Egypt

9. a. Mediterranean Sea (8 species)
Zosteraceae (Zostera),
Posidoniaceae (Posidonia),
Cymodoceaceae (Cymodocea, Halodule),
Hydrocharitaceae (Halophila).
Ruppiaceae (Ruppia)
Potamogetonaceae (Potamogeton)

10. Potamogeton pectinatus
Zostera marina
Zostera noltii
Posidonia oceanica
Cymodocea nodosa
Halodule uninervis
Halophila stipulacea
Ruppia cirrhosa
Potamogeton pectinatus

11. ? ? Present situation Situation in 1990 till early 2000
Posidonia oceanica
Cymodocea nodosa
Zostera marina
Zostera noltii
Posidonia oceanica
Cymodocea nodosa
Halophila stipulaceae
Posidonia oceanica
Cymodocea nodosa
Halophila stipulaceae
Posidonia oceanica
Halophila stipulacea ? ?
Present situation
Situation in 1990 till early 2000
Situation in
　　Seagrass distribution in the Mediterranean Sea coast of Egypt (Aleem 1962, 1955, Lipkin 1977, Vitiello et al. 1985, Mostafa 1991,　2006, Shabaka 2004)

12. Seagrass distribution in the northern lakes of Egypt
Potamogeton pectinatus
Ruppia cirrhosa,
Cymodocea nodosa,
Halodule uninervis,
Halophila stipulacea,
Potamogeton pectinatus
Zostera marina
Seagrass distribution in the northern lakes of Egypt

13. b. Red Sea (9 species)
Cymodoceaceae (Cymodocea, Halodule, Thalassodendron, Syringodium),
Hydrocharitaceae (Halophila, Thalassia).

14. Syringodium isoetifolium. Thalassodendron ciliatum
Cymodocea serrulata
Cymodocea rotundata
Halodule uninervis
Syringodium isoetifolium.
Thalassodendron ciliatum
Halophila decipiens
Halophila ovalis
Thalassia hemprichii
Halophila stipulacea

15. Halophila stipulaceae
Halophila ovalis
Halodule uninervis
Thalassia hemprichii
Present situation
None
Seagrass distribution in the Suez Canal lake El-Temsah and Bitter Lakes of Egypt (Aleem 1980)

16. Cymodocea serrulata and C
Cymodocea serrulata and C. rotundata were collected from El-Suweis (Lipkin 1975)
Distribution of seagrass in the Egyptian Red Sea Coast (after Geneid 2004).

17. III. Seagrass morphology and general taxonomy

18. Morphology of a seagrass unit

19. Seagrasses can be grouped into 3 main morphological categories:
Strap shaped leaves growing at the top of distinct erect stem
(Thalassia of Hydrocharitaceae and all Cymodoceaceae)
Strap shaped leaves but with very small erect stems
(Enhalus of Hydrocharitaceae, Posidoniaceae and Zosteraceae)
A pair of petiolate leaves at the rhizome nodes
Halophila

20. Key for seagrass genera
Leaves ligulate
Zosteraceae, Posidoniaceae, Cymodoceaceae
leaves without ligula (Hydrocharitaceae)
Halophila, Thalassia, Enhalus

21. Key for seagrass genera
Leaves with numerous tannin cells (Posidoniaceae, Cymodoceaceae)
Rhizome monopodial, herbaceous, with short lateral shoots, leaf sheath persistence more than the leaves
(Posidonia, syringodium, Halodule, Cymodocea)
Rhizome sympodial, woody, with elongate erect shoots
leaf blade shed with its sheath
(Thalassodendron, Amphibolis)
Leaves without tannin cells (Zosteraceae)
Syringodium isoetifolium.

22. Key for seagrass genera
Posidonia oceanica
Rhizomes are very thick (Posidonia)
Rhizomes are thin (Cymodocea, Halodule, Syringodium)
Syringodium isoetifolium.
Halodule uninervis
Cymodocea serrulata

23. Key for seagrass genera
Leaves with numerous tannin cells (Posidoniaceae, Cymodoceaceae)
Rhizome monopodial, herbaceous, with short lateral shoots, leaf sheath persistence more than the leaves (Posidonia, syringodium, Halodule, Cymodocea)
Rhizome sympodial, woody, with elongate erect shoots leaf blade shed with its sheath (Thalassodendron, Amphibolis)
Leaves without tannin cells (Zosteraceae)

24. Key for seagrass genera
leaves with numerous tannin cells (Posidoniaceae, Cymodoceaceae)
Rhizome monopodial, herbaceous, with short lateral shoots, leaf sheath persistence more than the leaves
(Posidonia, syringodium, Halodule, Cymodocea)
Rhizome sympodial, woody, with elongate erect shoots leaf blade shed with its sheath (Thalassodendron, Amphibolis)
leaves without tannin cells (Zosteraceae)
Thalassodendron ciliatum Amphibolis antarctica
After Den Hartog (1970)

25. Key for seagrass genera
Leaves with numerous tannin cells (Posidoniaceae, Cymodoceaceae)
Rhizome monopodial, herbaceous, with short lateral shoots, leaf sheath persistence more than the leaves (Posidonia, syringodium, Halodule, Cymodocea)
Rhizome sympodial, woody, with elongate erect shoots leaf blade shed with its sheath (Thalassodendron, Amphibolis)
Leaves without tannin cells (Zosteraceae)

26. Key for seagrass genera
Rhizomes monopodial, herbaceous, with a short lateral shoot at each node Zostera, Phyllospadix
Rhizomes sympodial, lignious, with two roots at each node and a stem that carries one leaf at each node. Heterozostera
Pyllospadix torreyi
Zostera marina
Heterozostera tasmanica

27. Key for seagrass genera
Leaves ligulate
Zosteraceae, Posidoniaceae, Cymodoceaceae
Leaves without ligula (Hydrocharitaceae)
Halophila, Thalassia, Enhalus
Enhalus acoroides
Thalassia hemprichii
Halophila ovalis

28. Thanks for your attention!