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Papers by mauro lenzi

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Eutrophication determines algal blooms and the subsequent accumulation of organic matter in sedim... more Eutrophication determines algal blooms and the subsequent accumulation of organic matter in sediments, which, in turn, results in the dominance of anaerobic respiratory processes that release toxic gases. Dystrophy is a final dissipative moment that reduces the organic load in the sediment. A case of dystrophy occurring in the Burano lagoon (Tuscany, Italy) in 2021 is reported. The study examined the weather, physico-chemistry of the water, submerged vegetation and sediment labile organic matter. In spring, dissolved oxygen (DO) and pH showed high values, in an abundance of submerged vegetation, while low values had ammonium, nitrate and orthophosphate. In mid-August, as warm and moist sea breezes prevailed, hydrogen sulfide releases were produced, preceded by a sharp rise in ammonium and orthophosphate concentrations, which remained high until November. During dystrophy, DO varied between anoxia and oversaturation, the latter in Cyanobacteria blooms. Dystrophic waters evolved gradu...

In the summer period 2004 and 2005 macrophytes (seaweeds and seagrasses) have been monitored in s... more In the summer period 2004 and 2005 macrophytes (seaweeds and seagrasses) have been monitored in some areas of 5 italian lagoons (Venice, Goro, Lesina, Taranto and Orbetello) in order to compare the flora of those transitional environments and their ecological conditions.

Chemistry and Ecology, 2009

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... di Ecologia Lagunare ed Acquacolura (LEALab), Orbetello Pesca Lagunare srl *** Central Instit... more ... di Ecologia Lagunare ed Acquacolura (LEALab), Orbetello Pesca Lagunare srl *** Central Institute for Marine Research (ICRAM) francesca.birardi@gmail ... S., CINELLI, F., CIRIK, S., COSSU, A., D'ARCHINO, R., DJELLOULI, SA, JAVEL, F., LANFRANCO, E., MIFSUD, C., PALA, D ...

I believe that greater reflection should be made on alien species. In my opinion, the hypothesis ... more I believe that greater reflection should be made on alien species. In my opinion, the hypothesis on which to work, should be to put the aliens more in relation with the weakening of the ecosystem structure caused by direct or indirect human actions. In this perspective, we could call the invasive allochthones “foreign opportunists”. Many examples could be given of how the resilience of a given ecosystem, if healthy or restored, allows the return to the original state, after an event has perturbed it, such as that of an invasive species (or at least that we think is to be attributed to this). In such cases, the alien species may disappear or remain completely resized. I have observed a similar case concerning invasive Chlorophyta Caulerpa cylindracea, which had previously completely covered an area behind an emerging barrier of Posidonia oceanica [1] and subsequently had been almost completely replaced by the typical communities of the phytobenthos [2]. The deterioration of the seagr...

Journal of Aquaculture Research & Development, 2016

1 Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, 117604 Rep... more 1 Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, 117604 Republic of Singapore. 2 Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543. 3 Institute of Aquatic Economic Animals, Sun Yat-sen University, Guangzhou, China. 4 College of Aqua-Life Science and Technology, Shanghai Ocean University, Shanghai 200090, China.

Aquaculture & Fisheries, 2019

The impact of wastewater from two fish farms affecting a coastal lagoon has been assessed for wat... more The impact of wastewater from two fish farms affecting a coastal lagoon has been assessed for water quality, sediments and macroalgae. Based on a previous study, three sampling areas of 135 hectares each were identified at increasing distance from the discharges and six monitoring surveys were carried out between May 2017 and November 2018. The results indicated macroalgal assemblages as the most suitable variables for assessing the impact of wastewater, since they showed a different species dominance in the three areas. No clear result emerged from sediments parameters due to the texture variability, while water quality was significantly different only for nitrates and orthophosphates in one of the three areas. Probably due to the specific lagoon morphology and eutrophication management methods adopted, only one of the surveyed areas was clearly affected by the wastewater impact.

Journal of Aquaculture Research & Development, 2015

Journal of Aquaculture & Marine Biology, 2017

This study analyzes the full-scale results of a three-year eutrophication control and management ... more This study analyzes the full-scale results of a three-year eutrophication control and management in the Orbetello lagoon. We examined the cause/effect relationship among the resuspension of top layer sediment in the water column (carried out by specifically designated boats), the labile organic matter present in the sediments (LOM), and the values of Chaetomorpha linum high density mats, which insist in the disturbed areas. LOM values resulted inversely associated to the frequency of sediment disturbance. LOM decrease, together with higher oxidation levels, triggered the reduction of nutrient release with an immediate effect on algal masses: the decay of the mat under layer prevailed on the growth of the mat over layer. Conversely, with a reduced frequency of disturbance, and the consequent increase of both the LOM as well as the anaerobic processes of the sediment which promote nutrient releases, the algal growth showed a time lag of several months, in which the nutrients uptake was likely intense. The stored nutrients were then used only some months later, when the environmental conditions became favorable for the surprisingly rapid and impressive development of the mats.

Marine Pollution Bulletin, 2016

Superficial soft sediment resuspension and partial fragmentation of high density opportunistic ma... more 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 9ha 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.

Marine Pollution Bulletin, 2003

Marine Pollution Bulletin, 2005

In the shallow water of Orbetello lagoon, macroalgae harvesting boats produce sediment disturbanc... more In the shallow water of Orbetello lagoon, macroalgae harvesting boats produce sediment disturbance. To evaluate the effect of this, during 2001-2002, a trial study was carried out in the lagoon in order to: verify seasonal and diurnal trends in nutrients and estimate the quantity of resuspended organic sediment. An unbalanced and balanced ANOVA (one and two way) analysis was applied. The disturbance did not produce strong and lasting eutrophication effects. In the seasonal survey, dissolved inorganic nitrogen (DIN) and soluble reactive phosphorus (SRP) showed significant decreases in disturbed areas at the end of the trial, while the control area showed a constant, significant increase. Dissolved organic nitrogen (DON) and phosphorus (DOP) significantly increased everywhere. In disturbed areas, sediment redox (Eh((NHE))) increased and porosity values decreased, contrary to the control area. Total organic carbon (TOC) remained unchanged in disturbed areas, but increased in the control area, where the C:P ration increased. The fall-out of sedimentary material resuspended by boat action for as far as 50 m from the boat route, was 189 g(dw)m(-2) made up mainly of organic matter. This disturbance could be the cause of change in vegetation in the lagoon.

Journal of Environmental Management, 2013

Harvesting of macroalgae by specially equipped boats in a shallow eutrophic lagoon produces evide... more Harvesting of macroalgae by specially equipped boats in a shallow eutrophic lagoon produces evident sediment resuspension. To outline the environmental effects of this disturbance, we examined the quantity of fall-out and the distances travelled by sediment and macronutrients from the source of boat disturbance. Resuspended sediment fall-out (RSFO) was trapped at different distances from the boat path to determine total dry weight, total nitrogen (TN), total carbon (TC), total organic carbon (TOC), total sulphur (TS) and total phosphorus (TP). The data was analysed by principal components analysis (PCA) and linear discriminant analysis (LDA) on PCA factors. Fall-out of C, N, S and P from the plume of resuspended sediment indicated significant re-arrangement of these nutrients: RSFO dry weight and S content decreased with distance from the boat path, whereas TP increased and was the variable responsible for most discrimination at 100 m. The mass of resuspended matter was relatively large, indicating that the boats considerably reshuffle lagoon sediment.

International Journal of Environment and Health, 2007

Estuarine, Coastal and Shelf Science, 2013

... Assessment of dystrophic risk indices based on standing crop evaluations. Mauro Lenzi 1 , Cor... more ... Assessment of dystrophic risk indices based on standing crop evaluations. Mauro Lenzi 1 , Corresponding Author Contact Information , E-mail The Corresponding Author , Monia Renzi 2 , Ugo Nesti 3 , Paola Gennaro 4 , Emma Persia 4 , Salvatore Porrello 4. ...

Aquaculture International, 2005