Social network analysis and the implications for Pontocaspian biodiversity conservation in Romania and Ukraine: A comparative study

optimal conservation are different. We end with sketching out conservation implications and recommendations for improved national and cross-border conservation efforts. Introduction Romania and Ukraine hold an important part of the Pontocaspian (PC) habitats in the North- ern part of the Black Sea Basin, which harbor aquatic PC community [1–3]. The PC biota com- prises endemic flora and fauna including mollusks, crustaceans, planktonic groups (e.g. dinoflagellates and diatoms) and fish species [3–5]. Currently, PC species numbers and abun- dances are in decline as a result of human activities and their future persistence strongly depends on the adequacy of conservation measures [3, 6, 7]. The distribution of PC species in Romania is limited to the Razim-Sinoe-Babadag lake complex [8, 9], the area along the Danube River and the Black Sea coastal zone, which together form the Danube Delta and have the sta- tus of Biosphere Reserve. In Ukraine, PC communities occur in the coastal lakes, deltas and estuaries from the Danube Delta in the south to the Dnieper estuary in the north and in the north-eastern part of the Sea of Azov [10–12]. The two countries share the responsibility of conserving the PC habitats and the associated threatened biota [9, 11, 13, 14]. However, they have different socio-political settings and histories. Romania is a member of the European Union (EU) since 2007, thus complying with the EU environmental policy, whereas Ukraine is an EU-associated country since 2017. Being part of the EU, Romania experiences continuous

adjustments in the institutional alignment [15] and a transformation of governance systems from authoritative state, to democratic and inclusive, multi-stakeholder systems [16]. This may result in different social environment in Romania to deal with biodiversity conservation issues compared to Ukraine [17]. In both countries Pontocaspian species are threatened and conservation measures are urgently required. In the past 30 years, the number, abundance and distribution ranges of PC species have decreased dramatically in Romania as a result of human influence [8, 9]. In Ukraine, PC species are declining as a result of habitat fragmentation caused by river damming and deep sea shipping lane constructions [18, 19]. Some of the PC species (e.g. some mollusk and sturgeon species) are of national concerns in both countries—they are recognized to be threatened and in need of conservation [8, 11, 13, 14]. Yet, indications exist that strong conser- vation measures are not in place to preserve these species and populations continue to decrease in both countries [8–10]. Biodiversity conservation is a complex task which involves different interests of various actors. Therefore, it is crucial that all types of stakeholder organizations are participating and interact at different stages of the process [20]. Effective exchange of scientific information, knowledge and conservation management experiences between stakeholder organizations determine the positive outcomes for biodiversity conservation [21–23]. Social network analysis

(SNA) is a commonly used tool to map and quantify these interactions. Social networks, defined as the sets of relationships among the stakeholder organizations, work as channels that facilitate the flow of information and provide opportunities for joint action and collaboration [24–26]. SNA uses a combination of mathematical formulae and models to describe and quan- tify the existing links among organizations [23]. In recent years, SNA has gained increased attention across a variety of domains including biodiversity conservation [27–29] and proved to be very informative for conservation planning [30]. PLOS ONE Social network analysis and the implications for Pontocaspian biodiversity conservation in Romania and Ukraine PLOS ONE | https://doi.org/10.1371/journal.pone.0221833 October 23, 2020 2 / 20