Testing and development of different metrics and indexes describing submerged aquatic vegetation for the assessment of the ecological status of semi-enclosed coastal water bodies in the NE Baltic Sea

Abstract

A national assessment system for the classification of the ecological status of coastal waters according to the requirements of the EU Water Framework Directive was established in Estonia in the year 2007. The Estonian Phytobenthos Index was used to assess the ecological status of coastal waters based on submerged aquatic vegetation. After the testing period it appeared that the selected method did not respond to anthropogenic pressure in two national water types: the Väinameri and Pärnu Bay. During this study new indexes were developed and validated against pressure for these areas. The PCF index was combined from the proportion of perennial species, charophytes, and Fucus spp. This index is suitable for the assessment of the ecological status in the Väinameri area. In Pärnu Bay the depth distribution of higher plants and the proportion of opportunistic species showed the strongest correlation with eutrophication variables. These metrics were combined into the HPO index. The class boundaries for assessing the ecological status of water quality were determined for both indexes. The paper describes the calculation of the indexes.

Implications of Macrophyte Distribution Patterns in the Curonian Lagoon for Monitoring of Submerged Vegetation in Transitional Water Bodies

“…2). Depth gradient is generally considered as a proxy for light availability and wave exposure, which affect the zonation of macrophyte species, their growth forms, coverage and biomass along this gradient (Chambers and Kalff, 1985;Torn et al, 2014).…”

“…4), where the mean SI cm was significantly higher at ≤ 1.0 m depth than at > 1.0 m depth (Games-Howell post hoc test, P < 0.05). Macrophyte species have a different light tolerance determining their maximum and optimal distribution depth (Chambers and Kalff, 1985;Torn et al, 2014). Unique community composition along the depth gradient in this way results in different intensity of autotrophic process.…”

Ecological Effects of Dam Impoundment on Closed and Half-Closed Wetlands in China

“…The water transparency of Erhai Lake in the Mekong watershed was 2.5 m. With the rise in the water level, the distribution depths of submerged plants changed from 6 m to 4 m. The water transparency of Lashi Lake became less than 3 m; submerged plants usually grow at depths of 1.0-2.8 m, and Hyalrilla verticillata was found in the bay of the lake, which had a transparency of 4.0 m. Both Fuxian Lake in the Pearl River watershed and Lugu Lake in the Yangtze watershed had high transparencies: Zannichellia palustris was found below a 10.0 m depth. Some studies have shown that clear water provides little atmospheric reflectance and either absorbs or transmits the majority of incoming radiation (Lillesand and Kiefer 1994;Verbyla 1995;Nelson et al 2006), therefore, the depth distribution of higher submerged plants is positively related to water transparency (Torn et al 2014), and the depth distribution of higher submerged plants has been used as part of a German assessment system (Selig et al 2007;Steinhardt et al 2009). These findings indicate that the wetland plants were strongly influenced by the water environment, and the submerged plants were primarily influenced by water transparency.…”