Scholarly record

HABITATS LOST: ANALYSIS OF THE EUTROPHICATION MAGNITUTE AT A PROTECTED COASTAL LAKE IN BULGARIA USING SATELLITE AND DRONE IMAGERY

Bogdan Prodanov, Radoslava Bekova, Iliyan Kotsev, Viktoriya Vachkova

Abstract

Transitional (brackish) water bodies host extremely vulnerable ecosystems. They are highly sensitive to pollution, changes in the water currents, nutrient levels, etc. Over the course of the 20th century in Bulgaria, many of them were purposely drained or strongly altered. Today, these fragile ecosystems account for just 0.1% of Bulgaria’s area, and hence they are listed among the country’s top priority nature conservation sites. The long-term preservation and survival of numerous rare or threatened hydrobionts depend on the conservation of these aquatic habitats. The site selected for the study herein is Maznia azmak. It represents a highly eutrophicated coastal lake (a former river bed) found in the Kamchia River’s downstream sector, contiguous to the mouth of the estuarine type, where it empties into the Black Sea. The study site represents a constituent part of Kamchia Nature Reserve and two Natura 2000 protected sites, i.e., BG0002045 Komplex Kamchia (Birds Directive) and BG0000116 Kamchia (Habitats Directive). The main goal of the present paper is to analyze the spatio-temporal changes, scale and rate of eutrophication at Maznia azmak and the related loss of sensitive aquatic habitats that are a subject to preservation. This has been achieved through GIS-based analysis and interpretation of archive topographic maps compiled at scale of 1:5,000-1:126,000, historical satellite and contemporary drone imagery. Results of the study demonstrate the constant expansion of the aquatic vegetation at the expense of open water surfaces. These findings imply for a deteriorated ecological status of the associated freshwater habitats in result of eutrophication.

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