Effects of nutrients and fish on periphyton and plant biomass across a European latitudinal gradient

Abstract

Replicated, factorial mesocosm experiments were conducted across Europe to study the effects of nutrient enrichment and fish density on macrophytes and on periphyton chlorophyll a (chl-a) with regard to latitude. Periphyton chl-a densities and plant decline were significantly related to nutrient loading in all countries. Fish effects were significant in a few sites only, mostly because of their contribution to the nutrient pool. A saturation-response type curve in periphyton chl-a with nutrients was found, and northern lakes achieved higher densities than southern lakes. Nutrient concentration and phytoplankton chl-a necessary for a 50% plant reduction followed a latitudinal gradient. Total phosphorus values for 50% plant disappearance were similar from Sweden (0.27 mg L -1 ) to northern Spain (0.35 mg L -1 ), but with a sharp increase in southern Spain (0.9 mg L -1 ). Planktonic chl-a values for 50% plant reduction increased monotonically from Sweden (30 lg L -1 ) to València (150 lg L -1 ). Longer plant growing-season, higher light intensities and temperature, and strong waterlevel fluctuations characteristic of southern latitudes can lead to greater persistence of macrophyte biomass at higher turbidities and nutrient concentration than in northern lakes. Results support the evidence that latitudinal differences in the functioning of shallow lakes should be considered in lake management and conservation policies.

The effect of periphyton on the light environment and production of Potamogeton perfoliatus L. in the mesotrophic basin of Lake Balaton

“…This decreased amount of light diminished the production of Potamogeton plants, which could lead to decreased growth of these plants as described in previous studies (Bécares et al 2008;Liboriussen and Jepessen 2009). Light attenuation of periphyton was the consequence of intense accumulation of both resuspended inorganic material and epiphytic algae, but this accumulation was not uniform through the season.…”

“…Traditionally, the maximum depth of penetration of rooted, submerged macrophytes is considered to depend mainly on water turbidity (e.g. Chambers and Kalff 1985;Jepessen et al 1997, Scheffer andNes 2007), shading effects of plankton and epiphyte biomass (Bécares et al 2008;Liboriussen and Jeppesen 2009;Scheffer et al 1992;Sand-Jensen and Borum 1991;Strand and Weisner 1996).…”

“…Biotic and abiotic light attenuation strongly influences the availability of light in the lower regions of the water column, and thus has a substantial impact on all autotrophic organisms and their community structure (Bécares et al 2008;Jones and Sayer 2003;Liboriussen and Jeppesen 2009). Periphyton, due to its high epiphytic algae content, is also influenced by changes in light attenuation (Jones et al 2002;Lalonde and Downing 1991;Müller 2006), while negatively 3 impacting both phytoplankton (Trochine et al 2011) and the plant substrate (Bécares et al 2008;Jones and Sayer 2003).…”

“…On the other hand, chlorophyll content and thickness of the epiphytic layer (Dodds et al 1999;Enríquez et al 1996) leads to a competitive interaction for light between periphyton and its macrophyte substrate (Bécares et al 2008;Jones and Sayer 2003). Thus, the specific depth distribution of epiphyte biomass directly influences light capture efficiency, morphology and physiology of macrophytes by additional attenuation of light at the adaxial side of leaves (Asaeda et al 2004;Sand-Jensen and Borum 1991;Sultana et al 2010).…”

The Biomass and Physiological Responses of Vallisneria natans (Lour.) Hara to Epiphytic Algae and Different Nitrate-N Concentrations in the Water Column

“…However, the overgrowth of epiphytic algae was seen to occur earlier than planktonic algae in eutrophic lakes and the reduction of submerged macrophytes was connected with a high epiphytic algae density [27,28]. In previous studies by Jones and Sayer [29] and Bécares et al [30], a 50% reduction of submerged macrophyte biomass occurred when epiphytic algal biomass exceeded 50 and 90 mg Chl-a m −2 , respectively. Therefore, the overgrowth of epiphytic algae rather than planktonic algae may be the most important factor leading to the loss of submerged macrophytes [23,31].…”