Decline of unique Pontocaspian biodiversity in the Black Sea Basin: A review

Abstract

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Legal Framework for Pontocaspian Biodiversity Conservation in the Danube Delta (Romania and Ukraine)

“…Spatial data on national PAs was retrieved from IUCN World Database on Protected Areas (WDPA, https://www.iucn.org/theme/ protected-areas/our-work/world-database-protected-areas). Data on PC habitats were retrieved from earlier work that defined, documented and mapped these habitats based on literature review and expert opinions (Gogaladze et al, 2021). We calculated the area of PC habitats and the percentage covered by PAs with a geometric overlying between the PC habitats and the PA polygons using QGIS 3.10 A Coruña.…”

“…One of the reasons for partial inclusion of PC invertebrate taxa in legal documents may be the lack of a consistent taxonomy, which has made the production of a list of PC invertebrate species virtually impossible till now. Clearly, the taxonomy of PC biota needs to be updated, i.e., the taxonomic synonymies fixed [see Supplementary Table 4, but also Wesselingh et al (2019) and Gogaladze et al (2021)], before policymakers can include them in the legal documents.…”

“…The current poor classification of estuarine and lagoonal habitats in the Bern Convention could be understood as a holistic, umbrella approach, which leads to the coverage of all components of the habitat e.g., entire benthic and planktonic communities. However, covering only the large estuarine habitat complex without further detail, the Bern Convention fails to separate the brackish characteristics of PC habitats from "marine" conditions of the estuarine mouth districts (Gogaladze et al, 2021). This is consequential for PC invertebrate community conservation, since human-induced changes in salinity regime as a result of canal constructions and barrier erections that cause a decline of PC species (Varbanov, 2002;Son, 2007b;Trichkova, 2007;van de Velde et al, 2019), are not formally considered as destruction to the biotope.…”

“…The Danube Delta shelters a unique, aquatic ecological community, known as the Pontocaspian (PC) biodiversity (Popa et al, 2009;van de Velde et al, 2019;Wesselingh et al, 2019), which is characterized by charismatic vertebrate species such as sturgeons, less-known invertebrate groups, such as mollusks and crustaceans, as well as diatoms and dinoflagellates (Grigorovich et al, 2003;Marret et al, 2004). Pontocaspian habitats comprise transitional zones between the freshwater and salt water bodies on coastal plains of the Black Sea and the Sea of Azov, such as lower stretches of rivers, lagoons, delta areas, estuaries, brackish lakes, and bays, as well as the entire Caspian Sea (Zenkevitch, 1963;Gogaladze et al, 2021). However, many PC species also inhabit fresh waters in lower reaches of large rivers.…”

“…However, many PC species also inhabit fresh waters in lower reaches of large rivers. Pontocaspian biota is threatened and rapidly declining due to direct anthropogenic drivers, such as damming of rivers, modification of marine and freshwater influx in coastal areas, and invasive species among others (Son, 2007a,b;van de Velde et al, 2019;Gogaladze et al, 2021), as well as indirect drivers, such as limited knowledge on PC species and suboptimal institutional cooperation of stakeholders (Wesselingh et al, 2019;Gogaladze et al, 2020a,b). The legal basis to address the decline of PC biodiversity has not been studied, with the exception of sturgeon species (Reinartz et al, 2012;Munteanu et al, 2013).…”