Land Use Changes Do Not Rapidly Change the Trophic State of a Deep Lake. Amvrakia Lake, Greece

Abstract

The study of physicochemical and biological parameters can assess the trend of a lake's trophic state. A trophic state index (TSI) was used to assess eutrophication of Lake Amvrakia. Total phosphorus and chlorophyll concentrations that recorded were generally at the same level with those recorded in previous years, a fact which indicates that lake's trophic state did not change. But in the past ten years, agricultural uses have been modified by almost 25% of the catchment area, because of the major reduction of tobacco cultivation. One year of monthly monitoring, in nine sampling stations can report this result. Even if the catchment is small and the agricultural areas are the 47% of the basin, the water quality of the lake did not change. The trophic state is stable probably because the lake is deep monomictic, and seasonally anoxic. For this reason internal phosphorus contribution is very important in the deep hypolimnion.

Long-Term Oxbow Lake Trophic State under Agricultural Best Management Practices

“…However, within-lake reductions in nutrients were apparent with mostly TP and dissolved inorganic N [23]. Previous research on lake restoration and improvement in trophic state through reductions in agricultural non-point sourced nutrients, wastewater sourced nutrients, biomanipulation via aquatic plants, or reducing fish populations has produced mixed results [6,15,16,54,55]. Most programs have focused on nutrient reductions with some limited short-term (<10 years) success for TP control and mitigation [54] while less is understood about TN control [54,56].…”

“…Despite these difficulties, decreasing nutrient concentrations in lakes through reduction in N and P loads is still viewed as an important first step in mitigating eutrophication and lake rehabilitation [7]. A useful tool for lake eutrophication assessment that incorporates the relationship between nutrients and algal blooms has been the Carlson-type trophic state index (TSI) [7] used in several lake studies over the last two decades [3,4,[11][12][13][14][15][16][17]. The index is valuable because calculation requires relatively few commonly measured lake water quality variables: Secchi depth visibility, nutrients (nitrogen, phosphorus), and chlorophyll a [3,4,7].…”

“…The index is valuable because calculation requires relatively few commonly measured lake water quality variables: Secchi depth visibility, nutrients (nitrogen, phosphorus), and chlorophyll a [3,4,7]. TSI has been utilized for lake management of water use (e.g., drinking water, fish, and wildlife use) [11,12], assist in lake ecoregional nutrient criteria development [13,14], assess the impacts of land-use, such as agriculture, on lake trophic state [3,4,15], and assess lake restoration success or recovery from storm events [16,17].…”

Trophic State Evaluation of a Large Mediterranean Lake Utilizing Abiotic and Biotic Elements

“…Tobacco cultivation was developed in the prefecture of Aitoloakarnania at the end of the 19 th century and this part of Greece became the country's major producing area of tobacco. However, from 1/1/2006 with the CAP reform in relation to tobacco cultivation, the overall production presented a significant reduction of about 80% in Greece and, specifically, 100% reduction in the whole prefecture of Aitoloakarnania [44]. As a result, tobacco producers either turned to other cultivations, or in most cases left their fields uncultivated.…”

Διερεύνηση Της Δυνατότητας Δημιουργίας Ιχθυολογικού Πολυμετρικού Δείκτη Για Την Εκτίμηση Της Οικολογικής Ποιότητας Λιμνών

“…Οι υψηλότερες τιμές του διαλυμένου οξυγόνου στη λίμνη Αμβρακία καταγράφηκαν στο μεταλίμνιο, ενώ στα βαθύτερα στρώματα του υπολίμνιου (βάθος > 42 m) καταγράφηκαν ισχυρά υποξικές συνθήκες (DO < 2 mg/l) που έχουν καταγραφεί και στο παρελθόν (Αλμπανάκης κ.ά. 1995a, Danielidis et al 1996, Thomatou et al 2013b.…”