Epiphytic Microalgal Species Composition and Dynamics on Host Green Seaweeds (Ulvaphyceae) on the Northern Coast of Jeddah, Saudi Arabia

Salim Marzoog Al-Harbi

doi:10.13189/eer.2017.050306

Abstract

Epiphytic microalgae on seaweeds are sessile microscopic plants grown with attached or associated to seaweeds hosts and seaweeds are multicellular and macroscopic macro-algae, which are abundant in intertidal zones of coastal environments. Study on epiphytic microalgae is rare at Jeddah coast of the Red Sea. Thus, an investigation on epiphytic microalgae species composition and dynamics on seaweeds of Ulvaphyceae was carried out at northern coast of Jeddah, the Red Sea. The Red Sea is narrow oceanic basin which is lying between the African and the Asian continental shelves. During the study, 3 species of seaweeds were recorded in Ulvaphyceae which were Chaetomorpha linum, Enteromorpha intestinalis and Ulva lactuca. A total of 70 epiphytic microalgae were identified, including 63 belong to Bacillariophyceae, 5 belong to Cyanophyceae and 2 belong to Dinophyceae. Among the identified epiphytic microalgae of the host seaweeds of Ulvaphyceae, the percent contribution of epiphytic Bacillariophyceae, Cyanophyceae and Dinophyceae were 91.53, 6.55 and 2.61%, respectively. The cell abundance of epiphytes on host seaweeds of Ulvaphyceae varied from 8.00 to 93.00 cells/ cells/100 g of Ulvaphyceae seaweeds. The highest cell abundance was in spring and the lowest was in summer. On host seaweeds of Ulvaphyceae, the epiphytes of Licmophora abbreviata, Gyrosigma fasciola, Leptocylindrus danicus, Navicula distans, Navicula transitans, Pleurosigma angulatum and Pleurosigma normanii, Thalassionema frauenfeldii and Nitzschia hungarica were above 10% among epiphytic microalgae though Amphora spp., and Cocconeis spp., were found throughout the year. This finding could be the important source for future explanation of marine epiphytes and their host seaweed eco-biogeographical phenomena in the Red Sea.

Highlights

Epiphytic microalgae on seaweeds are sessile microscopic plants grown with attached or associated to seaweeds hosts
Epiphytic microalgae are common constituents of aquatic systems and they are important in terms of productivity [6], and a suitable food source for higher trophic levels [7; 8] .The dynamics, abundance and community structure of epiphytic microalgae are influenced by biotic factors such as leaf age, seasonal cycle of the host, and grazing pressure by herbivores, and by the light, temperature, nutrients and water motion [3; 9 ; 10]
Three species of seaweeds of Ulvaphyceae were found throughout the year at the northern coast of Jeddah, the Red Sea. These species were available at Mastorah and Rabigh, and they were more in winter and spring. Those species found at different seasons and different area which made different habitats for epiphytic microalgae depending on local environmental conditions

Summary

Introduction

Epiphytic microalgae on seaweeds are sessile microscopic plants grown with attached or associated to seaweeds hosts. Seaweeds are multicellular and macroscopic macro-algae, which are abundant in intertidal zones of coastal environments. They grow in near-shore coastal waters with suitable substrates for attachment [1]. Marine Seaweeds play significant roles in the normal functioning of atmospheric environments even though seaweeds are restricted to the tide zones and benthic photic zones [1]. They contribute to about 10% of the total world marine productivity. They account for food and shelter for marine life They play an important role in the coastal carbon cycle and contribute remarkably to sea-farming activities. The abundant and diverse of epiphytic microalgae include diatoms, dinoflagellates and cyanobacteria which make a significant contribution to food webs

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Discussion

Conclusion