ISSN:
1573-5117
Keywords:
ammonium
;
competition
;
eutrophication
;
Gracilaria
;
seaweed
;
Ulva
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract In spring (August) 1993 a bloom of Ulva lactuca appeared for the first time in Saldanha Bay, South Africa, and persisted through summer. Ulva wash-ups contaminated the beach and part of the commercial Gracilaria beach-cast had to be discarded. The biomass and distribution of Gracilaria and Ulva are described in relation to the seasonal water chemistry of the bay. Gracilaria survives in deeper water in summer by the pulsing of nutrients on an approximately 6-day cycle of movement of the thermocline that separates nutrient-rich bottom water from warm oligotrophic surface water. Ammonium-rich fish-factory discharge into this surface layer in a sector of the bay provided localised conditions for Ulva to out-compete Gracilaria at depths of 2–5m, demonstrating the powerful disruptive effect of eutrophication in this strongly stratified system.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00047821
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