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Estimating the effects and timing of anthropogenic impacts on the composition of macrobenthic communities is challenging, because early twentieth-century surveys are sparse and the corresponding intervals in sedimentary sequences are mixed by bioturbation. Here, to assess the effects of eutrophication on macrobenthic communities in the northern Adriatic Sea, we account for mixing with dating of the bivalve Corbula gibba at two stations with high accumulation (Po prodelta) and one station with moderate accumulation (Isonzo prodelta). We find that, first, pervasively bioturbated muds typical of highstand conditions deposited in the early twentieth century were replaced by muds with relicts of flood layers and high content of total organic carbon (TOC) deposited in the late twentieth century at the Po prodelta. The twentieth century shelly muds at the Isonzo prodelta are amalgamated but also show an upward increase in TOC. Second, dating of C. gibba shells shows that the shift from the early to the late twentieth century is characterized by a decrease in stratigraphic disorder and by an increase in temporal resolution of assemblages from ~25–50 years to ~10–20 years in both regions. This shift reflects a decline in the depth of the fully mixed layer from more than 20 cm to a few centimeters. Third, the increase in abundance of the opportunistic species C. gibba and the loss of formerly abundant, hypoxia-sensitive species coincided with the decline in bioturbation, higher preservation of organic matter, and higher frequency of seasonal hypoxia in both regions. This depositional and ecosystem regime shift occurred in ca. a.d. 1950. Therefore, the effects of enhanced food supply on macrobenthic communities were overwhelmed by oxygen depletion, even when hypoxic conditions were limited to few weeks per year in the northern Adriatic Sea. Preservation of trends in molluscan abundance and flood events in cores was enhanced by higher frequency of hypoxia that reduced bioturbation in the late twentieth century.

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[1] The coherent description of water flow and solute transport within heterogeneous hydrologic media (e.g., hillslopes or entire catchments) in response to external rainfall forcings represents a challenge in hydrological modeling. In this paper the mechanisms determining the mobilization and transport of solutes in soils through the paths of runoff formation are investigated by means of a tracer experiment conducted within an instrumented hillslope draining into a tributary of the Dese river basin (northeastern Italy). The response of the test catchment during a rainfall event occurred at the beginning of December 2006 has been analyzed by employing two different chemical tracers: nitrates from diffuse agricultural sources (NO 3 À ) and lithium from a point injection (Li + ). Rainfall depths, streamflows, and pressure heads within different soil horizons were also collected. The observed hydro-chemical response of the Piovega Tre Comuni has been reproduced by a Mass Response Function solute transport model. Our results evidence the origins of the chromatographic effects seen in the system's response. In particular, the deep subsurface component of runoff is found to dominate the long-term behavior of the hydrograph and proves responsible for exporting relatively large amounts of solutes from soil. Experimental evidences and modeling results also suggest that the behavior of the breakthrough curve in stream waters may be strongly affected by the persistence of the rainfall forcing and by the relative magnitude of the rainfall-driven hydrologic contribution with respect to the background noise unrelated to soil moisture dynamics.