Diatom assemblages in a reservoir sediment core track land-use changes in the watershed

Abstract

Diatom assemblages in a 144-cm sediment core reliably chronicled watershed changes and modifications of a riverine water-source reservoir in northeastern Ohio (USA) between 1932 and 2005. Non-metric Multidimensional Scaling segregated diatom assemblages into six groups that correspond to known anthropogenic modifications in the watershed and reservoir: zone I (filling, 1932-1936), zone II (high farming activity, [1937][1938][1939][1940][1941][1942][1943][1944][1945][1946][1947][1948][1949], zone III (declining farm activity and increased residential development, 1950-1976), zone IV (implementation of sewage bypass, 1977-1982), reduced development activity caused by economic recession, 1983-1993), zone VI (renewed population growth and construction of a dam extension, 1994-2005). Ten watershed and reservoir environmental variables (percent farmland, population, pH, total alkalinity, total hardness, transparency, surface area, air temperature, export of suspended solids, total phosphorus) were significantly correlated with diatom aggregate distribution in ordination space. Changes in species composition, in concert with watershed and reservoir changes, implicated light, alkalinity, and littoral macrophyte development as the primary drivers of diatom aggregate structure and function. Diatom productivity did not track nutrient loading (TP) and was likely driven by factors other than nutrients. Each zone was defined by a distinct set of environmental variables that differed from all other zones. Thus, diatom aggregate structure likely was determined by a dynamic suite of factors in the watershed and reservoir that had differential effects on diatom aggregate structure through time.

A 1600-year record of human impacts on a floodplain lake in the Mississippi River Valley

“…The groupings of diatom assemblages were highly significant (p = 0.001) using Analysis of Similarities (ANOSIM). The overlap among pre-and post-abandonment samples implies that shifts in communities were gradual, similar to the lagged community response observed in a reservoir in Ohio (Schroeder et al 2016). In Horseshoe Lake, we also observe a lagged community response following historic EuroAmerican settlement, although the most recent samples score highly on Axis 2 (Fig.…”

“…NMDS is a non-parametric method that assumes no particular response function (Minchin 1987), thereby avoiding the ''Arch Effect'' and modifications of ordination axes. NMDS was used by Schroeder (2016) to study the human impacts on diatom assemblages in a core from an Ohio reservoir.…”

Epipelic Diatoms to Determine Ecological Status Based on Diatom Index in Mangrove Ecosystem of Morosari Village, Indonesia

“…The presence of Fragilaria nanana indicates eutrophic water conditions [Siringoringo et al, 2018]. Cyclostephanos dubius was also found at a depth of 110 cm which is a planktonic diatom with a centric shape and lives in high alkalinity waters so it is considered an indicator of eutrophic water conditions [Schroeder et al, 2016].…”

Assessing the degree of ecological change and baselines for reservoirs: challenges and implications for management

“…Furthermore, several proxies have been employed to provide interpretations of ecosystem changes in response to anthropogenic impacts in reservoirs. Diatoms are a well-known proxy, sensitive to changes in productivity (Woodbridge et al 2014;Schroeder et al 2016), and geochemical markers can also be particularly valuable to trace the history of trophic changes (Filstrup et al 2010;Kumar et al 2016). A combination of both geochemical and biological proxies has been recently used with success to determine environmental change in reservoirs in North and South America (Winston et al 2014;Fontana et al 2014).…”