Causes and effects of the remarkable regression of the macroalga Ulva rigida C. Ag. in the central part of the Venice lagoon since 1990 are reported. Climatic changes triggered the progressive reduction of Ulva coverage and production (-80% in 1993; -95% in 1995) until its almost complete disappearance in 1996. Grazers, especially Gammaridae, controlled 70% of the current biomass production, on a yearly basis, and largely overcame the biomass production in summer Concurrently, the sediment resuspension increased by a factor of 6-10 in the lagoon areas where the biomass disappeared contributing significantly to control of the growth of the residual biomass by light limitation, especially by settling of a microlayer of sediment over the laminar thalli. Finally, biomass harvesting, now effective, and the heavy disturbance caused by fishing boats equipped with hydraulic dredges to catch Tapes philippinarum, a bivalve species recently introduced into the lagoon and spread in the areas previously covered by Ulva, currently play an important synergistic role in Ulva control. Conversely, the overall availability of nutrients did not appear to have any significant influence on the observed macroalgal decline.

Decline of Ulva growth in the lagoon of Venice

SFRISO, Adriano;MARCOMINI, Antonio
1996-01-01

Abstract

Causes and effects of the remarkable regression of the macroalga Ulva rigida C. Ag. in the central part of the Venice lagoon since 1990 are reported. Climatic changes triggered the progressive reduction of Ulva coverage and production (-80% in 1993; -95% in 1995) until its almost complete disappearance in 1996. Grazers, especially Gammaridae, controlled 70% of the current biomass production, on a yearly basis, and largely overcame the biomass production in summer Concurrently, the sediment resuspension increased by a factor of 6-10 in the lagoon areas where the biomass disappeared contributing significantly to control of the growth of the residual biomass by light limitation, especially by settling of a microlayer of sediment over the laminar thalli. Finally, biomass harvesting, now effective, and the heavy disturbance caused by fishing boats equipped with hydraulic dredges to catch Tapes philippinarum, a bivalve species recently introduced into the lagoon and spread in the areas previously covered by Ulva, currently play an important synergistic role in Ulva control. Conversely, the overall availability of nutrients did not appear to have any significant influence on the observed macroalgal decline.
1996
58
File in questo prodotto:
File Dimensione Formato  
Decline of Ulva growth.pdf

non disponibili

Tipologia: Documento in Post-print
Licenza: Accesso chiuso-personale
Dimensione 823.31 kB
Formato Adobe PDF
823.31 kB Adobe PDF   Visualizza/Apri

I documenti in ARCA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10278/13245
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 74
  • ???jsp.display-item.citation.isi??? 73
social impact