title: Physico-chemical and nutrient variable stratifications in the water column and in macroalgal thalli as a result of high biomass mats in a non-tidal shallow-water lagoon.
abstract: A field study to check parameter stratification during high density growth of four opportunistic macroalgae was carried out in Orbetello lagoon (Italy). The effects of macroalgal masses were compared with a seagrass meadow and two lagoon areas with bare bottoms as controls for pH, temperature, dissolved oxygen, salinity, nitrite, nitrate ammonium and orthophosphate. The nutrient content of thalli and sediment redox were measured. Macroalgae showed differences in stratification of thalli nutrient content. Mat with low density and high volume produced stratifications in the water column, but it did not produce nutrient release by sediment. In contrast, high density and low and high volume mats led to sharp falls in dissolved oxygen, with negative values of sediment Eh and anoxic trigger processes that presumably led to release of sediment nutrients. This depended on thallus type: heavy thalli compacted the mat and light ones distributed more widely in the water column.
authors.affiliation: Lagoon Ecology and Aquaculture Laboratory (LEALab), Orbetello Pesca Lagunare Company, Via G. Leopardi 9, 58015 Orbetello, Italy. Electronic address: lealab2@hotmail.com.
authors.forename: Mauro
authors.initials: M
authors.lastname: Lenzi
authors.affiliation: Higher Institute for Environmental Protection and Research (ISPRA), Via di Casalotti 300, 00166 Rome, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Gennaro
authors.affiliation: Higher Institute for Environmental Protection and Research (ISPRA), Via di Casalotti 300, 00166 Rome, Italy.
authors.forename: Isabel
authors.initials: I
authors.lastname: Mercatali
authors.affiliation: Higher Institute for Environmental Protection and Research (ISPRA), Via di Casalotti 300, 00166 Rome, Italy.
authors.forename: Emma
authors.initials: E
authors.lastname: Persia
authors.affiliation: Lagoon Ecology and Aquaculture Laboratory (LEALab), Orbetello Pesca Lagunare Company, Via G. Leopardi 9, 58015 Orbetello, Italy.
authors.forename: Duccio
authors.initials: D
authors.lastname: Solari
authors.affiliation: Higher Institute for Environmental Protection and Research (ISPRA), Via di Casalotti 300, 00166 Rome, Italy.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Porrello
mesh_terms: D018533:Biomass; D004784:Environmental Monitoring; D005068:Eutrophication; D019015:Geologic Sediments / Q000737:chemistry; D007558:Italy; D009584:Nitrogen / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis*; D054712:Salinity; D012623:Seawater / Q000737:chemistry*; D012624:Seaweed / Q000502:physiology*; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data
chemical_list: D014874:Water Pollutants, Chemical; D010758:Phosphorus; D009584:Nitrogen
keywords: Eutrophication; Macroalgal mat; Macroalgal thalli; Nutrient; Shallow water; Top–bottom stratification