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Synopsis on Seagrass of Egypt, Seagrass Morphology and General Taxonomy Dr. Soha Shabaka Hydrobiology Laboratory National Institute of Oceanography and.

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Presentation on theme: "Synopsis on Seagrass of Egypt, Seagrass Morphology and General Taxonomy Dr. Soha Shabaka Hydrobiology Laboratory National Institute of Oceanography and."— Presentation transcript:

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!


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