Defining and recording the loss of species diversity is a daunting task, especially if identities of species under threat are not fully resolved. An example is the Pontocaspian biota. The mostly endemic invertebrate faunas that evolved in the Black Sea – Caspian Sea – Aral Sea region and live under variable salinity conditions are undergoing strong change, yet within several groups species boundaries are not well established. Collection efforts in the past decade have failed to produce living material of various species groups whose taxonomic status is unclear. This lack of data precludes an integrated taxonomic assessment to clarify species identities and estimate species richness of Pontocaspian biota combining morphological, ecological, genetic, and distribution data. In this paper, we present an expert-working list of Pontocaspian and invasive mollusc species associated to Pontocaspian habitats. This list is based on published and unpublished data on morphology, ecology, anatomy, and molecular biology. It allows us to (1) document Pontocaspian mollusc species, (2) make species richness estimates, and (3) identify and discuss taxonomic uncertainties. The endemic Pontocaspian mollusc species richness is estimated between 55 and 99 species, but there are several groups that may harbour cryptic species. Even though the conservation status of most of the species is not assessed or data deficient, our observations point to deterioration for many of the Pontocaspian species.

No abstract

No abstract

This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

22 23 Abstract 24 Romania and Ukraine share the Black Sea coastline, the Danube Delta and associated habitats, 25 which harbor the unique Pontocaspian biodiversity. Pontocaspian biota represents endemic 26 aquatic taxa adapted to the brackish (anomalohaline) conditions, which evolved in the Caspian 27 and Black Sea basins. Currently, this biota is diminishing both in the numbers of species and28 their abundance because of human activities. Consequently, its future persistence strongly 29 depends on the adequacy of conservation measures. Romania and Ukraine have a common 30 responsibility to effectively address the conservation of this biota. The socio-political and legal 31 conservation frameworks, however, differ in the two countries -Romania is a member of the 32 European Union (EU), thus complying with the EU environmental policy, whereas Ukraine is an 33 EU-associated country. This may result in differences in the social network structure of 34 stakeholder institutions with different implications for Pontocaspian biodiversity conservation.35 Here, we study the structure and implications of the social network of stakeholder organizations 36 involved in conservation of Pontocaspian biodiversity in Romania, and compare it to Ukraine. 37 We apply a mix of qualitative and quantitative social network analysis methods to combine the 38 content and context of the interactions with relational measures. We show that the social 39 networks of stakeholder organizations in Romania and Ukraine are very different. Structurally, in 40 Romanian network there is a room for improvement through e.g. more involvement of 3 41 governmental and non-governmental organizations and increased motivation of central 42 stakeholders to initiate conservation action, whereas Ukrainian network is close to optimal. 43 Regardless, both networks translate into sub-optimal conservation action and the road to optimal 44 conservation is different. We end with sketching implications and recommendations for 45 improved national and cross-border conservation efforts. 46 47 Introduction 48 Pontocaspian (PC) biota is a unique, endemic flora and fauna which includes mollusks, 49 crustaceans, planktonic groups (e.g. dinoflagellates and diatoms) and fish species. This 50 biodiversity evolved in brackish (anomalohaline) conditions of the Black Sea and Caspian Sea 51 basins over the past 2.5 million years [1,2] and nowadays PC communities inhabit the Northern 52 Black Sea, Sea of Azov, Caspian Sea and adjacent river and lake systems, stretching across the 53 vast political and administrative boundaries of the surrounding countries [3]. Currently, PC biota 54 is decreasing in numbers of species and abundances as a result of human activities and their 55 future persistence strongly depends on the adequacy of conservation measures [1,4,5]. Romania 56 and Ukraine hold an important part of the PC habitats. PC species in Romania are limited to the 57 Razim-Sinoe-Babadag lake complex [6,7], the area along the Danube River and the Black Sea 58 coastal zone, which t...

Romania and Ukraine share the Black Sea coastline, the Danube Delta and associated habitats, which harbor the endemic, aquatic Pontocaspian biota. Currently, this biota is diminishing both in numbers of species and their abundance because of human activities, and its future persistence strongly depends on the adequacy of conservation measures. Romania and Ukraine have a common responsibility to address the conservation of Pontocaspian biodiversity. The two countries, however have different socio-political and legal conservation frameworks, which may result in differences in the social network structure of stakeholder institutions with different implications for Pontocaspian biodiversity conservation. Here, we study the social network structure of stakeholder organizations involved in conservation of Pontocaspian biodiversity in Romania and the implications of network structure for conservation outcomes. Then we compare the findings from Romania to an earlier similar study from Ukraine. We apply a mix of qualitative and quantitative social network analysis methods to combine the content and context of the interactions with relational measures. We show that Pontocaspian biodiversity plays a minor and mostly incidental role in the inter-organizational interactions in Romania. Furthermore, there is room for improvement in the network structure through e.g. more involvement of governmental and nongovernmental organizations and increased motivation of central stakeholders to initiate conservation actions. Social variables, such as lack of funding, hierarchical, non-inclusive system of conservation governance and continuous institutional reforms in the public sector are consequential for the network relations and structure. Social network of stakeholders in Ukraine is more connected and central stakeholders utilize their favorable positions. However, neither in Ukraine is the Pontocaspian biodiversity a driver of organizational interactions. Consequently, both networks translate into sub-optimal conservation actions and the roads to optimal conservation are different. We end with sketching out conservation implications and recommendations for improved national and cross-border conservation efforts.

The declining biodiversity has upsetting consequences for social and economic development and represents a major concern for humanity. Legal and political framework plays an important role in biodiversity conservation planning, implementation, and coordination of actions. Legal provisions are complex and operate on different levels of governance (from supranational to national), which means that the status of single species or populations may be governed by a set of interacting or even conflicting regulations, with increasing complexity for species that occur across national borders. Romania (EU member state) and Ukraine (non-EU member state) exemplify neighboring countries with different governance systems, which share the same endemic aquatic communities inhabiting the transitional zones between freshwater and marine ecosystems, known regionally as Pontocaspian (PC) biota. These communities include flagship species such as sturgeons and less-known crustaceans and mollusks and are severely threatened as a result of human activities. We assessed the legal basis for the protection of PC biota in the Danube Delta and the effectiveness of current conservation approaches based on a review of legal documents and literature, expert opinion, and practitioner reflections regarding PC biodiversity conservation. We found that PC invertebrate species are not adequately addressed in the current legal documents and that the surrogate approach (where protection of umbrella species results in protection of background species) does not work as there is little overlap between the habitats of sturgeons and PC invertebrate communities. Furthermore, the habitat definitions currently used in legal documents lack the level of detail needed to protect PC habitats that are characterized by specific salinity (brackish) conditions. We finish by sketching out recommendations toward improved legal and political frameworks for effective and efficient conservation of PC invertebrate biota.

Aim The unique aquatic Pontocaspian (PC) biota of the Black Sea Basin (BSB) is in decline. Lack of detailed knowledge on the status and trends of species, populations and communities hampers a thorough risk assessment and precludes effective conservation. This paper aims to review PC biodiversity trends using endemic molluscs as a model group. We aim to assess changes in PC habitats, community structure and species distribution over the past century and to identify direct anthropogenic threats. Location Black Sea Basin (Bulgaria, Romania, Moldova, Ukraine and Russia). Methods Presence/absence data of target mollusc species was assembled from literature, reports and personal observations. PC biodiversity trends in the NW BSB coastal regions were established by comparing 20th and 21st century occurrences. Direct drivers of habitat and biodiversity change were identified and documented. Results A very strong decline of PC species and communities during the past century is driven by a) damming of rivers, b) habitat modifications negatively affecting salinity gradients, c) pollution and eutrophication, d) invasive alien species and e) climate change. Four out of 10 studied regions, namely, the Danube Delta – Razim Lake system, Dniester Liman, Dnieper-South Bug Estuary and Taganrog Bay-Don Delta contain the entire spectrum of ecological conditions to support PC communities and still host threatened endemic PC mollusc species. Distribution data is incomplete, but the scale of deterioration of PC species and communities is evident from the assembled data, as are major direct threats. Main conclusions PC biodiversity in the BSB is profoundly affected by human activities. Standardised observation and collection data as well as precise definition of PC biota and habitats are necessary for targeted conservation actions. This study will help to set the research and policy agenda required to improve data collection to accommodate effective conservation of the unique PC biota.