Economic costs of non-native species in Türkiye: A first national synthesis.

Biological invasions are increasingly recognised as a major global change that erodes ecosystems, societal well-being, and economies. However, comprehensive analyses of their economic ramifications are missing for most national economies, despite rapidly escalating costs globally. Türkiye is highly vulnerable to biological invasions owing to its extensive transport network and trade connections as well as its unique transcontinental position at the interface of Europe and Asia. This study presents the first analysis of the reported economic costs caused by biological invasions in Türkiye. The InvaCost database which compiles invasive non-native species' monetary costs was used, complemented with cost searches specific to Türkiye, to describe the spatial and taxonomic attributes of costly invasive non-native species, the types of costs, and their temporal trends. The total economic cost attributed to invasive non-native species in Türkiye (from 202 cost reporting documents) amounted to US$ 4.1 billion from 1960 to 2022. However, cost data were only available for 87 out of 872 (10%) non-native species known for Türkiye. Costs were biased towards a few hyper-costly non-native taxa, such as jellyfish, stink bugs, and locusts. Among impacted sectors, agriculture bore the highest total cost, reaching US$ 2.85 billion, followed by the fishery sector with a total cost of US$ 1.20 billion. Management (i.e., control and eradication) costs were, against expectations, substantially higher than reported damage costs (US$ 2.89 billion vs. US$ 28.4 million). Yearly costs incurred by non-native species rose exponentially over time, reaching US$ 504 million per year in 2020-2022 and are predicted to increase further in the next 10 years. A large deficit of cost records compared to other countries was also shown, suggesting a larger monetary underestimate than is typically observed. These findings underscore the need for improved cost recording as well as preventative management strategies to reduce future post-invasion management costs and help inform decisions to manage the economic burdens posed by invasive non-native species. These insights further emphasise the crucial role of standardised data in accurately estimating the costs associated with invasive non-native species for prioritisation and communication purposes.

A global-scale screening of non-native aquatic organisms to identify potentially invasive species under current and future climate conditions.

The threat posed by invasive non-native species worldwide requires a global approach to identify which introduced species are likely to pose an elevated risk of impact to native species and ecosystems. To inform policy, stakeholders and management decisions on global threats to aquatic ecosystems, 195 assessors representing 120 risk assessment areas across all six inhabited continents screened 819 non-native species from 15 groups of aquatic organisms (freshwater, brackish, marine plants and animals) using the Aquatic Species Invasiveness Screening Kit. This multi-lingual decision-support tool for the risk screening of aquatic organisms provides assessors with risk scores for a species under current and future climate change conditions that, following a statistically based calibration, permits the accurate classification of species into high-, medium- and low-risk categories under current and predicted climate conditions. The 1730 screenings undertaken encompassed wide geographical areas (regions, political entities, parts thereof, water bodies, river basins, lake drainage basins, and marine regions), which permitted thresholds to be identified for almost all aquatic organismal groups screened as well as for tropical, temperate and continental climate classes, and for tropical and temperate marine ecoregions. In total, 33 species were identified as posing a 'very high risk' of being or becoming invasive, and the scores of several of these species under current climate increased under future climate conditions, primarily due to their wide thermal tolerances. The risk thresholds determined for taxonomic groups and climate zones provide a basis against which area-specific or climate-based calibrated thresholds may be interpreted. In turn, the risk rankings help decision-makers identify which species require an immediate 'rapid' management action (e.g. eradication, control) to avoid or mitigate adverse impacts, which require a full risk assessment, and which are to be restricted or banned with regard to importation and/or sale as ornamental or aquarium/fishery enhancement.

The influence of environmental instability on the reproductive strategy of the critically endangered Acigöl killifish (Aphanius transgrediens).

To investigate the variability in the reproductive tactics of Acigöl killifish (Aphanius transgrediens), one of the most seriously threatened freshwater teleost species, this study compared its reproductive ecology in two contrasting habitats that differ substantially in terms of stability of environmental parameters, particularly salinity regime (stable vs. unstable). Fish were sampled monthly from October 2013 to September 2014 with the aim of testing whether the reproductive life-history response of fish to stable and unstable conditions differed. The reproductive effort (gonad weight) of both sexes did not differ significantly between the two habitats, but females in the unstable habitat had significantly lower fecundity and larger eggs. The relationship between fecundity and fish size was stronger in the stable habitat, whereas the relationship was quite variable and uncertain in the unstable habitat. Fish born in the unstable habitat reached their first maturity at a smaller size than those in the stable habitat. The gonado-somatic index and the duration of hydrated eggs showed that reproduction continued from February to May in both habitats; nonetheless, a second spawning event occurred during July and August in the unstable habitat, which included the reproductive contributions of YOY individuals and older generations. This study's results suggest that A. transgrediens employs varying reproductive strategies against environmental instability in its restricted unique range. This may have further implications for the ways in which habitat-specific conservation methods are used.

Three new species of Alburnoides from the southern Black Sea basin (Teleostei: Cyprinidae).

Three new Alburnoides species are described from the southern Black Sea basin. Alburnoides kurui, new species, from the Yesilirmak drainage, is distinguished from other species of Alburnoides in the southern Black Sea basin, the Marmara basin and the Anatolian Aegean basin by having a scaleless keel between the posterior pelvic fin base and the anus or with rarely 1 scale covering the anterior part of the keel; 50-59 total lateral-line scales; 13½-15½ branched anal-fin rays and 7-9 gill rakers. Alburnoides freyhofi, new species, from the Kizilirmak drainage, is distinguished by having a scaleless keel between the posterior pelvic fin base and the anus, 44-53 total lateral-line scales; 14½-16½ branched anal-fin rays and 5-7 gill rakers. Alburnoides kosswigi, new species, from the Sakarya drainage, is distinguished by having a scaleless keel between the posterior pelvic fin base and the anus or rarely with 1-3 scales covering the anterior part of the keel; 43-57 total lateral-line scales; 11½-13 (14)½ branched anal-fin rays and 5-7 gill rakers.

A new species of Pseudophoxinus (Teleostei: Cyprinidae) from Southwestern Anatolia, Turkey.

Pseudophoxinus mehmeti, new cyprinid species from the Alanköy basin in south-western Turkey, is distinguished from all species of Pseudophoxinus in adjacent regions by the combination of the following characters: body slender, its length 1.3-1.5 times its depth; caudal peduncle length 1.6-2.0 times its depth; mouth almost superior, with the tip of the mouth-cleft approximately level with the middle of the pupil; snout with a pointed tip, its length markedly greater than eye diameter; lateral line not complete, with 30-50 perforated scales and 48-60+2 scale rows in lateral series; 11½-13½ scale rows between lateral line and dorsal-fin origin, 3½-5½ scale rows between lateral line and anal-fin origin; dorsal-fin with 6½-7½ branched rays; anal-fin with 6½-7½ branched rays; a distinct black epidermal stripe from eye to caudal-fin base in preserved individuals.

Natural thermal adaptation increases heat shock protein levels and decreases oxidative stress.

Heat shock proteins (HSPs), originally identified as heat-inducible gene products, are a family of highly conserved proteins that respond to a wide variety of stress including oxidative stress. Although both acute and chronic oxidative stress have been well demonstrated to induce HSP responses, little evidence is available whether increased HSP levels provide enhanced protection against oxidative stress under elevated yet sublethal temperatures. We studied relationships between oxidative stress and HSPs in a physiological model by using Garra rufa (doctor fish), a fish species naturally acclimatized to different thermal conditions. We compared fish naturally living in a hot spring with relatively high water temperature (34.4±0.6°C) to those living in normal river water temperature (25.4±4.7°C), and found that levels of all the studied HSPs (HSP70, HSP60, HSP90, HSC70 and GRP75) were higher in fish living in elevated water temperature compared with normal river water temperature. In contrast, indicators of oxidative stress, including protein carbonyls and lipid hydroperoxides, were decreased in fish living in the elevated temperature, indicating that HSP levels are inversely associated with oxidative stress. The present results provide evidence that physiologically increased HSP levels provide protection against oxidative stress and enhance cytoprotection.

Three new species of Alburnoides (Teleostei: Cyprinidae) from Euphrates River, Eastern Anatolia, Turkey.

Three new species of Alburnoides, Alburnoides emineae sp. n., Alburnoides velioglui sp. n., Alburnoides recepi sp. n., are described from the Euphrates River drainages (Persian Gulf basin) in eastern Anatolia, Turkey. Alburnoides emineae, from Beyazsu Stream (south-eastern Euphrates River drainage), is distinguished from all species of Alburnoides in Turkey and adjacent regions by a combination of the following characters (none unique to the species): a well developed ventral keel between pelvic and anal fins, commonly scaleless or very rarely 1-2 scales covering the anterior portion of the keel; a deep body (depth at dorsal-fin origin 31-36% SL); 37-43 + 1-2 lateral-line scales, 13½-15½ branched anal-fin rays; number of total vertebrae 41-42, modally 41, comprising 20-21 abdominal and 20-21 caudal vertebrae. Alburnoides velioglui, from Sirli, Karasu, Divrigi and Sultansuyu streams (northern and northeastern Euphrates River drainages), is distinguished by a poorly developed ventral keel, completely scaled; a moderately deep body (depth at dorsal-fin origin 24-29% SL); 45-53 + 1-2 lateral-line scales, 11½ -13½ branched anal-fin rays; number of total vertebrae 41-42, modally 42, comprising 20-22 abdominal and 20-21 caudal vertebrae. Alburnoides recepi, from Merzimen Stream (southern Euphrates River drainage), is distinguished by a well developed ventral keel, completely scaleless; a deep body (depth at dorsal-fin origin 29-34% SL); 47-56 + 2-3 lateral-line scales; 13½-16½ branched anal-fin rays; number of total vertebrae 38-40, comprising 19-21 abdominal and 18-20 caudal vertebrae.

Alburnoides manyasensis (Actinopterygii, Cyprinidae), a new species of cyprinid fish from Manyas Lake basin, Turkey.

Alburnoides manyasensis, sp. n., is described from the Koca Stream (Lake Manyas drainage, Marmara Sea basin) in Anatolia. It is distinguished from all species of Alburnoides in Turkey and adjacent regions, Alburnoides tzanevi (Rezovska [Rezve], Istranca and Terkos streams in the western Black Sea drainage), Alburnoides cf. smyrnae (Banaz Stream, a drainage of Büyük Menderes River, Aegean Sea basin), Alburnoides fasciatus (streams and rivers in the eastern Black Sea drainage) and Alburnoides eichwaldii (Kura and Aras rivers [a drainage of Kura River], Caspian Sea basin) by a combination of the following characters (none unique to the species):marked hump at nape, especially in specimens larger than 60 mm SL; partly developed ventral keel between pelvic fin and anal fin, scaleless 1/2 to 2/3 its length; body depth at dorsal-fin origin 29-32% SL; caudal peduncle depth 11-12% SL; 45-52+ 2-3 lateral-line scales; 9-12 scale rows between lateral line and dorsal-fin origin; 4-5 scale rows between lateral line and anal-fin origin, 10½-12½ branched anal-fin rays; 40-42 total vertebrae.

Molecular phylogeny of the genus Gobio Cuvier, 1816 (Teleostei: Cyprinidae) and its contribution to taxonomy.

The phylogenetic relationships among gudgeons that represent most nominal taxa within Gobio gobio sensu lato were examined by mitochondrial and nuclear genome sequencing. The molecular analyses confirmed the separate generic status of Gobio as a monophyletic group and revealed 15 Eurasian lineages divided into two main clades, the Northern European and the Ponto-Caspian. The validity of eleven nominal taxa as distinct species was confirmed, gudgeons from the Volga River basin were described as a new species G. volgensis, and three revealed phylogenetic lineages were submitted for a comprehensive revision as "species-in-waiting". The species G. gobio showed a wide range extending from the British Isles to the Black Sea coast and overlapped the areas of several other species. Four pure lineages were detected in the middle Danube River basin. The Crimean Peninsula was found to be a region with the occurrence of individuals of hybrid origin. This region will require special investigation to define species participating in hybridization events, and to establish further steps for the conservation of endemic native gudgeon species. A simple diagnostic method, based on different lengths of the PCR products, called "S7indel diagnostics" is presented for further taxonomic investigations in the genus Gobio.

Divergence with gene flow between Ponto-Caspian refugia in an anadromous cyprinid Rutilus frisii revealed by multiple gene phylogeography.

The Black and Caspian Seas have experienced alternating periods of isolation and interconnection over many Milankovitch climate oscillations and most recently became separated when the meltwater overflow from the Caspian Sea ceased at the end of the last glaciation. Climate-induced habitat changes have indisputably had profound impacts on distribution and demography of aquatic species, yet uncertainties remain about the relative roles of isolation and dispersal in the response of species shared between the Black and Caspian Sea basins. We examined these issues using phylogeographical analysis of an anadromous cyprinid fish Rutilus frisii. Bayesian coalescence analyses of sequence variation at two nuclear and one mitochondrial genes suggest that the Black and Caspian Seas supported separate populations of R. frisii during the last glaciation. Parameter estimates from the fitted isolation-with-migration model showed that their separation was not complete, however, and that the two populations continued to exchange genes in both directions. These analyses also suggested that majority of migrations occurred during the Pleistocene, showing that the variation shared between the Black and Caspian Seas is the result of ancient dispersal along the temporary natural connections between the basins, rather than of incomplete lineage sorting or recent human-mediated dispersal. Gene flow between the refugial populations was therefore an important source of genetic variation, and we suggest that it facilitated the evolutionary response of the populations to changing climate.