Phytoplankton ecology and production of the Red Sea off Jiddah, Saudi Arabia

Shaikh, Essam Abid (1982). Phytoplankton ecology and production of the Red Sea off Jiddah, Saudi Arabia. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000fca2

Abstract

The Red Sea, being a landlocked, semi-enclosed body of water located in an arid zone where evaporation is far in excess of precipitation and run-off, offers a unique ecosystem from the tropical region. During 1977-78 off Jiddah, physical, chemical and biological data were collected at an eutrophicated inshore Sharm station and a relatively unpolluted offshore station. The prevailing high temperatures, high salinity and lack of land drainage resulted in highly stratified dense waters with little or no vertical admixture. There was not always an abundant supply of nutrients in these waters but, due to monsoonal activity, domes of high phosphate, silicates, nitrates and ammonia were noticed both in the offshore and inshore waters. Biological production, measured as phytoplankton cell numbers, chlorophyll a and primary production, also increased usually
with a time-lag between the nutrients and production. Depending on the monsoonal currents, periodic recruitment and exchange of Red Sea component, Mediterranean component. Nile estuarine component and Indo-Pacific components of phytoplankton takes place. The annual phytoplankton cycle follows a bimodal pattern with the peaks of production coinciding with the activity of the monsoons.

The magnitude of production was higher in the offshore waters and the production in the study area was higher than in several temperate and tropical waters. The high carbon assimilation ratios suggest a high efficiency of photosynthesis characteristic of sun-adapted phytoplankton. Based on the photosynthetic production, it is speculated that a rich fishery potential exists in the Red Sea.