NW Adriatic Sea biogeochemical variability in the last 20 years (1986–2005)

Abstract

Abstract. This paper presents a long-term time series (1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005) of hydrological and biogeochemical data, both published and unpublished. Data were collected in the northwestern area of the Adriatic Sea, at two stations that are considered hydrodynamically and trophically different. The time series have been statistically and graphically analysed on a monthly scale in order to study the annual climatologies, links between the concentrations of chlorophyll-a and the variability in the environment, trophic differences between the two areas and chlorophyll-a trends over time. Basically, the two areas have similar hydrological features, yet they present significant differences in the amount of nutrient inputs: these are in fact higher at the coastal site, which is characterized by a prevalence of surface blooms, while they are lower at the offshore station, which is mainly affected by blooms at intermediate depths. Nonetheless, throughout the whole water column, chlorophyll-a concentrations are only slightly different. Both areas are affected by riverine discharge, though chlorophyll-a concentrations are also driven strongly by the seasonal cycle at the station closer to the coast. Results show that the two stations are not trophically different, although some controlling factors, such as zooplankton grazing in one case and light attenuation in the other, may further regulate the growth of phytoplankton. In both cases no significant trends are detected in either the average chlorophyll-a values or in dispersion of the data, in contrast with significant trends in temperature and salinity.

Current state, scales of variability, and trends of biogeochemical properties in the northern Adriatic Sea

“…This result provides a broader picture, in which to frame (1) the results of Tedesco et al [2007], who used 20‐year‐long time series of two stations in northwestern Adriatic Sea and concluded that at least in one of the two stations a significant positive trend is detectable, and (2) the results of Malačič et al [2006], who reported an increment in temperature by analyzing 10‐year‐long time series of the Gulf of Trieste (out of our study area). Russo et al [2002] also reported an increment in temperature, deducted by comparing a pool of observations recorded between 1911 and 1987 with a second pool of records from 1988 to 1999.…”

Recent Trends Towards Oligotrophication of the Northern Adriatic: Evidence from Chlorophyll a Time Series

“…Right panels: day-ofthe-year distribution box plots for the earlier and recent (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007) periods. Ticks of x axes signal the first day of the month total period of interest in this study, while Tedesco et al (2007) considered the last 20 years, but only at two sites, and detected a significant increase for only one of them. Solidoro et al (2009) analyzed the whole Northern Adriatic basin but advanced very little evidence supporting the hypothesis of a significant warming of Northern Adriatic waters during the last 30 years.…”

“…Most studies, however, were based on data referring to a specific site, such as the Gulf of Trieste (Cataletto et al 1995;Conversi et al 2009;Fonda Umani et al 2004;Kamburska and Fonda Umani 2006;Mozetič et al 1998;Solidoro et al 2007), the coastal area in front of Venice (Bernardi Aubry et al 2004), the central part of the basin (Degobbis et al 2000), and the Po delta area (Tedesco et al 2007), while a few studies attempted to address a regional basin scale (Solidoro et al 2009;Zavatarelli et al 1998).…”

Influence of winds and oceanographic conditions on the mucilage aggregation in the Northern Adriatic Sea in 2003–2006

“…2005) and could contribute to the accumulation of organic carbon leading to mucilage formation. However, in the last decades no increasing trend in the phytoplankton biomass in the NA has been observed (Tedesco et al. 2007), suggesting that the composition of phytoplankton and the coupling with meteorological and oceanographic conditions are more important than just the total biomass concentration.…”