Seagrass and macroalgal diversity in the Egyptian waters.

Dr. Soha Shabaka

National Institute of Oceanography and Fisheries (NIOF)

Egypt

1. Introduction

Seagrasses and macroalgae are considered to be very important benthic primary producers. Both

communities are important habitats for invertebrates, fishes, and mammals, where these organisms use

seagrasses and macroalgal habitats as shelter, feeding and breeding grounds. Accordingly, loss of any

of these valuable habitats could have severe impacts on the regional biodiversity and ecosystem

functioning and consequently on human social and economic interest through reductions in

ecologically and economically important species.

Macroalgae grow on rocky bottom where they can attach and extend from the splash zone to subtidal

areas. There depth limit depends on the light and suitable substrata availability. Seagrasses prefer to

grow over soft bottom substrata where they make vast meadows with network of roots and rhizomes

similar to terrestrial plants. Seagrasses extend from intertidal zone to deep areas and their depth limit

depends on light availability. Seagrass depth limit is used as a bioindicator of water quality. The global

diversity of seagrass is very low (about 60 species) in comparison to hundreds of species of

macroalgae.

2. Seagrass and macroalgal diversity along the Mediterranean Sea coast of Egypt.

Few researches have been conducted to study the biodiversity of macroalgae and seagrasses along

the Mediterranean Sea coast of Egypt and mostly are old records and concentrated along the shores of

Alexandria City. There is a lack of information on the distribution of seagrasses along the northwest

Mediterranean coast of Egypt which if explored, would give amazing discoveries concerning pristine

seagrass meadows which mainly composed of Posidonia oceanica.

Lipkin (1977) recorded three seagrass species along the Mediterranean Sea coast of Egypt;

Cymodocea nodosa, Posidonia oceanica and Zostera noltii. The only record of Zostera marina from

Alexandria waters was reported by Nasr and Aleem (1949). Aleem (1960) recorded Aleem (1962)

recorded Posidonia oceanica, Cymodocea nodosa and Halophila stipulaceae from Marsa Matrouh

harbor western end of Mediterranean coast of Egypt. Halophila stipulacea is a recent immigrant from

the Red Sea. According to Aleem (1962) and Lipkin (1972), Halophila stipulacea has reached Port

Said successfully and colonized several areas in the Eastern Mediterranean Coast of Egypt. At

El-Dabaa 160 Km from Alexandria Posidonia oceanica and Cymodocea nodosa were recorded

(Viliello et al. 1985).

Several seagrass species were recorded from Bardawil Lake on the north Mediterranean shore of the

Sinai Peninsula, Egypt. Three seagrass species was recorded by El-Bana et al. (2002); these are Ruppia

cirrhosa, Cymodocea nodosa, Halodule uninervis. Moreover, Halophila stipulacea, Potamogeton

pectinatus and Zostera marina were recently observed in a Fieldwork observation (Shabaka). Among

these species, Halodule uninervis and Halophila stipulacea migrated from the Red sea through the

Suez Canal and can be considered as invasive species.

Twenty-two dives were performed from October 2000 to August 2001 to study seagrass distribution

along Alexandria coast from Al-Agami to Montazah Bay, from very shallow waters to about 15 m

depth, using skin and scuba diving (Shabaka 2004) and were compared to the survey conducted by

Mostafa (1999) along Alexandria Coast. The survey revealed a complete destruction of the meadows

of both Posidonia oceanica and Cymodocea nodosa. Cymodocea nodosa meadow was found only in

Montazah Bay, east of Alexandria, Posidonia oceanica was found also in Montazah Bay but was

represented by very small, weak patches covered with the brown algae Colpomenia sp. In Al-Agami,

Posidonia balls and leaves were cast ashore in huge amounts, however, meadows of Posidonia

oceanica were not observed during the survey. It was suggested that a regression of Posidonia

oceanica meadows to greater depths has occurred.

There are few published reports on marine macroalgae from the Egyptian waters. Khalil (1987)

reported 116 taxa of benthic marine algae along Alexandria coast from Abu-Qir Bay to Al-Agami,

including 30 Chlorophyceae, 28 Phaeophceae and 58 Rhodophyceae.

Chlorophyceae: Anadyomene steillata, Bryopsis hypnoides, B. pennatula, B. plumose, Caulerpa

prolifera, C. scaipelliformis, Chaetomorpha aerea, Ch. linum, Cladophora albida, Cl. gacilis, Cl.

pellucida, Cl. prolifera, Cl. refracta, Cl. rupestris, Cl. utriculosa, Codium bursa, Co. elongatum, Co.

tomentosum, Co. vermilara, Enteromorpha clathrata, E. compressa, E. flexuosa, E. intestinalis, E.

Linza, Halimeda tuna, Udotea petiolata, Ulva fasciata, U. lactuca, U. rigida, and Valonia utricularis.

Phaeophyceae: Cladostephus verticillatus, Colpomenia peregrine, Co. sinuosa, Cystoseira discors,

C. compressa, C. spinosa, C. tamariscifolia, Dictyopteris membrancea, Dictyota dichotoma, D.

Linearis, Dilophus fasciola, Ectocarpus confervoides, E. siliculosus, Halopteris scoparia,

Hydroclathrus clathratus, Nereia filiformis, Padina pavonia, Petalonia fascia, Punctaria latifolia,

Sargassum hornschuchii, S. salicifolium, Scytosiphon lomentaria, Spatoglossum solierii, Sp. variabile,

Sp. tribuloides, Stilophora rhizodes and Taonia atomaria.

Rhodophyceae: Acanthophora najadiformis, Amphiroa rigida, Bangia fuscopurpurea, Botrycladia

botryoides, Callithamnion granulatum, Centroceras clavulatum, Ceramium ciliatum, C. diphanum, C.

gardneri, C. rurbum, C. tenuissimum, Champia parvula, Chrysymenia ventricosa, Corallina granifera,

Co. mediterranea, Co. officinalis, Dasya pedicellata, Erythrotrichia reflexa, Glidium crinale, G.

latifolium, Gigartina teedii, Gracilaria arcuata, Gracilaria armata, Gr. bursa-pastoris, Gr. dura, Gr.

verrucosa, Griffithsia furcellata, Halopitys incurvus, Halymenia fastigiata, H. floresia,

Herposiphonia tenella, Hypnea musciformis, Hypoglossum woodwardii, Jania adhaerens, J. rubens,

Laurencia obtuse, L. paniculata, L. papillosa, L. pinnatifida, Liagora viscida, Lithophyllum incrustans,

Lomentaria articulate, Nemalion helminthoides, Polysiphonia breviarticulata, P. brodiaei, P.

nigrescens, P. Opaca, P. sertularioides, Porphyra leucosticte, Pterocladia capillacea, Pterosiphonia

pennata, Rhodochorton purpureum, Rhodymenia palmetto, Rytipholea tinctoria, Scinaia furcellata

and Spyrida filamentosa.

3. Seagrass and macroalgal diversity along the Red Sea coast of Egypt.

The seagrasses species recorded in the Red Sea were more diversified than those in the

Mediterranean Sea. Seven tropical genera were recorded, four (Halodule, Halophila, Syringodium and

Thalassia) were found in both the Atlantic and Indo-pacific regions and the other three genera

(Enhalus, Cymodocea, and Thalassodendron) were found only in the Indo-Pacific region (Den Hartog

1970). In the Gulf of Aqaba and Gulf of Suez, Halophila stipulacea, H. ovalis and Halodule uninervis

were observed (Wahbeh 1980, Geneid 1995, 2004). Geneid (2004) recorded recently a total of six

species belonging to five genera along the Egyptian Red Sea coasts; Halophila stipulacea, Halophila

ovalis, Halodule uninervis, Thalassia hemprichii, Thalassodendron ciliatum and Syringodium

isoetifolium. The latter species were collected from different sites beginning from Ain Sukhna (40 km

south of Suez City) to Abu Ramad in the South (20 km North the Egyptian-Sudanese boarder) and

from Ras Burka (35 km south Taba) to Sharm El-Sheik City at the south of Gulf of Aqaba. Cymodocea

serrulata and C. rotundata were collected from El-Suweis (Lipkin 1975).

Aleem (1978a, 1987b), studied the algae in the vicinity of Al-Ghardaqa, Red Sea coast of Egypt and

recorded 37 species of green algae, 25 species of brown algae and 47 species of Red algae. In the Suez

Canal, Aleem (1980) recorded 34 species of green algae, 20 species of brown algae and 56 species of

red algae. Negm (1988) surveyed the algal flora inhabiting the upper intertidal zone of the Egyptian

coast of the Red Sea at the vicinity of Al-Ghardaqa during 1979-1980 and identified a total of 57

species (18 belong to green algae; 18 brown algae and 21 Red algae). The dominant species were

Sargassum latifolium, Sargassum asperifolium, Sargassum crispum, Jania rubens, Cystoseira trinodis,

Ulva lactuca and Halimeda tuna. Twenty-three species of Cyanobacteria were found as epiphytes

colonizing the macrophytes (Negm 1988).

4. References

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