Effect of temperature variations on growth, reproduction, amino acid synthesis, fat and sugar content in ulva fasciata delile plants

Abstract

This work deals with the effect of temperature variations on growth, reproduction, amino acid synthesis, fat and sugar content in Ulva fasciata in habiting the littoral region of the Mediterranean shore bordering Alexandria.

Higher temperatures above 30°C have lethal effects on some parts of the algal fronds while the other parts are rather resistant. The latter are scattered groups of cells, which usually regenerate new plants when carried even to distant parts due to detrimental action of waves and currents. They serve a good means for vegetative propagation and spread better than zooids, which probably perish under such severe and violent conditions.

The rate of growth of Ulva indicated by the increase in dry weight and total nitrogen, increases at rising temperature till the latter becomes limiting.

Higher temperatures favour the growth and development of sporophytic phases, known by their deep green colouration, while temperatures below 20°C favour the production of gametophytes, identified by their yellowish green colour. This might explain why most of the algal crops of Ulva fasciata produced from parental stock (3 crops per year i.e. annually), are sporophytes.

Moderate temperatures were favourable for growth, reproduction and the various metabolic processes. Amino acids and sugar contents increase with the rise of temperature, reaching their maximum around 25°C, while fat content increases at still lower temperatures.