Artificial soft sediment resuspension and high density opportunistic macroalgal mat fragmentation as method for increasing sediment zoobenthic assemblage diversity in a eutrophic lagoon. Issue 1 (15th September 2016)

• Record Type: Journal Article
• Authors: Martelloni, Tatiana; Tomassetti, Paolo; Gennaro, Paola; Vani, Danilo; Persia, Emma; Persiano, Marco; Falchi, Riccardo; Porrello, Salvatore; Lenzi, Mauro
• Is Part Of: Marine pollution bulletin. Volume 110:Issue 1(2016:Sep.)
• Page Start: 212
• Page End: 220
• Publication Date: 2016-09-15
• Subjects: Sediment disturbance -- Sediment resuspension -- Lagoon -- Eutrophication -- Zoobenthic assemblages -- Lagoon remediation; Marine pollution -- Periodicals; Marine Biology -- Periodicals; Water Pollution -- Periodicals; Mer -- Pollution -- Périodiques; Publications périodiques; Pollution des mers; Lutte antipollution; Electronic journals; 363.7394
• DOI: 10.1016/j.marpolbul.2016.06.060
• Languages: English
• ISSNs: 0025-326X

Abstract

Abstract: Superficial soft sediment resuspension and partial fragmentation of high density opportunistic macroalgal mats were investigated by boat to determine the impact on zoobenthic assemblages in a eutrophic Mediterranean lagoon. Sediment resuspension was used to oxidise superficial organic sediments as a method to counteract the effects of eutrophication. Likewise, artificial decay of macroalgal mat was calculated to reduce a permanent source of sediment organic matter. An area of 9 ha was disturbed (zone D) and two other areas of the same size were left undisturbed (zones U). We measured chemical–physical variables, estimated algal biomass and sedimentary organic matter, and conducted qualitative and quantitative determinations of the zoobenthic species detected in sediment and among algal mats. The results showed a constant major reduction in labile organic matter (LOM) and algal biomass in D, whereas values in U remained stable or increased. In the three zones, however, bare patches of lagoon bed increased in size, either by direct effect of the boats in D or by anaerobic decay of the algal mass in U. Zoobenthic assemblages in algal mats reduced the number of species in D, probably due to the sharp reduction in biomass, but remained stable in U, whereas in all three areas abundance increased. Sediment zoobenthic assemblages increased the number of species in D, as expected, due to drastic reduction in LOM, whereas values in U remained stable and again abundance increased in all three zones. In conclusion, we confirmed that reduction of sediment organic load enabled an increase in the number of species, while the algal mats proved to be an important substrate in the lagoon environment for zoobenthic assemblages, especially when mat alternated with bare intermat areas of lagoon bed. Sediment resuspension is confirmed as a management criterion for counteracting the effects of eutrophication and improving the biodiversity of zoobenthic assemblages in eutrophic lagoon environments. Highlights: Reduction of labile organic matter by boat disturbance increased sediment zoobenthic diversity Macroalgal mat represented an important substrate for macrozoobenthos in eutrophic environment Bare bottom inter-mat improved zoobenthic diversity in high density mats compared to full coverage The ratio between zoobenthic species number in algae and sediment decreased with decreasing sediment organic matter. When labile organic matter in sediment is high, zoobenthic species find refuge in the top of algae mat.