Trophic transfer, bioaccumulation and translocation of microplastics in an international listed wetland on the Montreux record.

Microplastics (MPs) are concerning emerging pollutants. Here, MPs in four edible aquatic species of different trophic levels (between ∼2 and 4), including fish species Esox lucius (Esocidae: Esocinae); Cyprinus carpio (Cyprinidae: Cyprininae); and Luciobarbus caspius (Cyprinidae: Barbinae); and the swan mussel Anodonta cygnea (Unionidae), were assessed in the Anzali freshwater ecosystem. It is a listed wetland in the Montreux record. MPs were extracted from gastrointestinal tracts (GI), gills, muscles, and skin. All the studied fish and mussels (n = 33) had MPs. MP fibres, fragments and sheets were detected in every GI examined, however, fibres were the only type of MPs in skins, muscles and gills and were the most abundant MP. The MPs found in the fish and mussels were mainly made of nylon (35% of the total MPs), polypropylene-low density polyethylene (30%), and polycarbonate (25%). The average numbers of MPs found in every fish specimen, expressed per wet body mass, had a moderate negative correlation with the condition factor (K) (MP/g - K: Pearson correlation r = -0.413, p = 0.049), and there was no significant relation with the growth factor (b) (r = -0.376; p = 0.068). Importantly, Luciobarbus caspius (with trophic level 2.7-2.8) bioaccumulated MPs and presented a strong correlation between their MP contamination and age (r = 0.916 p < 0.05). Greater gill mass (or related factors) played an important role in the accumulation of MPs, and there was a strong correlation between these factors for Esox lucius and Cyprinus carpio (r = 0.876; r = 0.846; p < 0.05 respectively). The highest MP/g gills (1.91 ± 2.65) were in the filter feeder Anodonta cygnea inhabiting the benthic zone. Esox lucius (piscivorous, trophic level 4.1) was the most contaminated species overall (a total of 83 MPs in 8 individuals, with 0.92 MP/g fish), and their gills where MPs mainly accumulated. Cyprinus carpio was the most contaminated specimen (MPs in specimens), while the number of MPs per mass unit increased with the trophic level. Their feeding and ecological behavior in the aquatic habitat affected the level of accumulation. This work includes evidence of translocation of MPs within the aquatic organisms.

Otoliths of Caspian gobies (Teleostei: Gobiidae): Morphological diversity and phylogenetic implications.

Otoliths (ear stones) of the inner ears of teleost fishes, which develop independently from the skeleton and are functionally associated with hearing and the sense of equilibrium, have significantly contributed to contemporary understanding of teleost fish systematics and evolutionary diversity. The sagittal otolith is of particular interest, since it often possesses distinctive morphological features that differ significantly among species, and have been shown to be species- and genus-specific, making it an informative taxonomic tool for ichthyologists. The otolith morphology of the Caspian Sea gobiids has not been thoroughly studied yet, with data available for only a few species. The aim of the present paper is to examine the qualitative and quantitative taxonomic and phylogenetic information in the sagittal otoliths of these species. A total of 118 otoliths representing 30 gobiid species (including 53.5% of the Caspian gobiofauna) in three gobiid lineages (i.e., Gobius, Pomatoschistus, and Acanthogobius) and 11 genera (i.e., all Ponto-Caspian gobiid genera except Babka) were analysed at taxonomic levels using an integrated descriptive and morphometric approach. The results indicated high taxonomic efficiency of otolith morphology and morphometry at taxonomic levels for the Ponto-Caspian gobiids. Our qualitative and quantitative otolith data also (i) support the monophyly of neogobiin gobies, (ii) along with other morphological and ecological data, offer a new perspective on the systematics of Neogobius bathybius, (iii) suggest the reassignment of Hyrcanogobius bergi to the genus Knipowitschia, and (iv) question the phylogenetic integrity of the four phenotypic groups previously defined in the tadpole-goby genus Benthophilus; however, more studies are needed to complete these evaluations and confirm our otolith study findings.

Characterization of ingested MPs and their relation with growth parameters of endemic and invasive fish from a coastal wetland.

Microplastic (MP) contamination is a persistent and ubiquitous threat to aquatic ecosystems. This study quantifies MP ingestion by fish inhabiting the Anzali Wetland (Iran), a hotspot of biodiversity. Growth parameters have been monitored in endemic demersal fish (Caspian spined loach, Sabanejewia caspia), and invasive benthopelagic species (Prussian carp, Carassius gibelio) in the wetland and compared with their internal content of MPs. MPs were extracted from the gastrointestinal (GI) tracts following digestion of the samples in alkaline medium and observation of the extracts with microscopy (Scanning Electron Microscopy equipped with an Energy-Dispersive X-ray microanalyzer (SEM-EDS) and confocal Raman microscopy). A total of 84.6 % of the study fish (n = 26) were contaminated with MPs. Fibres were the only type of MPs found in the GI tracts, and these were mainly dark blue and made of polycarbonate and nylon in both investigated species. The mean numbers of MPs in the GI tracts of the carp and the loach were 3.6 and 3.7 respectively. MPs had smooth surfaces in most cases although some presented brittle, fragmented, and uneven surfaces and signs of degradation. The growth rates of Carassius gibelio and Sabanejewia caspia, measured with the b value (growth factor), were 2.91 and 2.15 respectively. Carassius gibelio can play a significant role in the transport of MPs to other aquatic organisms inhabiting the Anzali wetland, and hence can cause potential harm to them. Carassius gibelio MP contamination was more pronounced with increasing gut mass in older specimens. Due to the presence of MPs and in fish that can be consumed, there could be a trophic transfer to humans. Regarding Sabanejewia caspia, although not statistically significant, their uptake of MPs tends to increase in older specimens with smaller size and body weight. This can imply that MP pollution causes inappropriate conditions and results in negative growth. The findings of this work provide new insights into MP contamination in the Anzali wetland, specifically in endemic fish. These results will be important in conservation and management programs.

An integrative insight into the diversity, distribution, and biogeography of the freshwater endemic clade of the Ponticola syrman group (Teleostei: Gobiidae) in the Caucasus biodiversity hotspot.

Freshwater habitats of the Caucasus biodiversity hotspot represent a center of endemism for the gobiid genus Ponticola Iljin, 1927. Hitherto, large-scale molecular studies, owing to restricted taxon and geographical sampling, have failed to give an elaborate picture of diversity and evolutionary history of these species. Here, to contribute to filling this gap, we assessed taxonomic diversity, phylogeography and evolutionary history for the south Caspian populations of Ponticola presently classified as P. iranicus and P. patimari, using an integrative taxonomic approach comprising an entire geographic range sampling, and analyses of mitochondrial DNA haplotypes, the head lateral line system, otolith shape, and meristic and morphometric variation. All freshwater samples of the P. syrman group belong to a monophyletic clade with two main subclades: a small subclade confined to the upper Sefidroud sub-basin including the type locality of P. iranicus and a large subclade with three geographically constrained haplogroups (Hg1, Hg2, and Hg3), comprising the rest of the distribution. Hg1 showed an eastern distribution including the type locality of P. patimari, while Hg2 and Hg3 are sister groups with central and western-central distributions, respectively. The freshwater clade diverged from P. syrman during the Tyurkyanian low stand (~150 m b.s.l. lasting ~0.1 Myr), while the divergence of P. iranicus and P. patimari and radiations within P. patimari took place during the Bakunian high stand (up to 50 m a.s.l. lasting ~378-480 kya). Species delimitation analyses indicated two distinct species, corresponding to each main subclade. Although the otolith shape and lateral line analyses did not reflect with phylogeographic pattern, PCA and DFA plots of meristic and morphometric data showed a clear separation of the two major subclades corresponding to P. iranicus and P. patimari, suggesting the presence of significant morphological variation meriting formal taxonomic recognition. Overall, our findings (i) reveal the presence of two freshwater endemic species in the P. syrman group, and pending further investigation, hypothesize the presence of a third cryptic species; (ii) revise and document a narrow distributional range and low diversity for P. iranicus, in contrast to a wider distributional range and high diversity for P. patimari; (iii) suggest that the climatic oscillations of the Pleistocene were associated with the cladogenesis within the P. syrman group; and (iv) allowed for the recognition of conservation units and proposition of management measures.

Ponticola hircaniaensis sp. nov., a new and critically endangered gobiid species (Teleostei: Gobiidae) from the southern Caspian Sea basin.

Ponticola hircaniaensis sp. nov. is described as a new gobiid species from the Kaboudval Stream, southern Caspian Sea basin. The new species is diagnosed among Caspian Sea basin Ponticola species by the following combination of characters: second dorsal-fin branched rays 1416, anal-fin branched rays 1012, scales in lateral series 5259; lower jaw slightly, if at all, prognathous; head and body yellowish brown showing a reticulate brown pattern on a yellow background, first dorsal fin with a marginal bright orangish-yellow band and a dark anterior spot, upper part of pectoral-fin base with a distinct dark brown stripe; length of third spine in first dorsal fin 13.418.3 % of standard length (SL), second dorsal-fin spine length 11.113.8 % SL, caudal peduncle length and depth 16.420.1 % and 11.112.8 % SL, respectively, head depth at nape 70.981.0 % of head length (HL), and at eye 52.566.0 % HL; sagittal otolith dorsal rim with a broad concavity in the middle, dorsal depression absent or indistinct, sulcus length/sulcus height and sulcus height/otolith height ratios 1.471.82 and 0.340.40, respectively. It is also characterised by a K2P nearest neighbour distance of 5% to P. kessleri in the mtDNA COI barcode region. Mitochondrial and nuclear DNA analyses suggested extensive hybridization between P. hircaniaensis sp. nov. and P. gorlap at Kaboudval, providing evidence for the first record of hybridization in the Ponto-Caspian gobiids. Based on narrow geographic range isolated above the Zarrin Gol Dam (< 2 km2), extensive hybridization with P. gorlap, and other threats, the new species should be considered Critically Endangered.

Gobies (Teleostei: Gobiidae) of the oldest and deepest Caspian Sea sub-basin: an evidence-based annotated checklist and a key for species identification.

An evidence-based annotated checklist of gobiid species (Teleostei: Gobiidae) inhabiting the South Caspian Sea and its catchment area (i.e., the South Caspian Sea sub-basin) is compiled. The South Caspian Sea sub-basin gobiofauna currently comprises 38 confirmed species in 11 genera (i.e., 88.4% of the Caspian gobiofauna); the most diverse genus is Benthophilus (16 species, 42.1%), followed by Ponticola (seven species, 18.4%), and Neogobius (four species, 10.5%). Ten species (26.3%) are endemic to the South Caspian Sea sub-basin, another 21 species (55.3%) are endemic in the Caspian Sea basin as a whole, six (15.8%) are native to the Ponto-Caspian region, and one species (2.6%) is exotic. According to the current IUCN Red List, 24 species (64.9%) are listed as being of "Least Concern", eight species (21.6%) are "Data Deficient", and five species (13.5%) as "Not Evaluated". Similar numbers of species are confirmed to inhabit the South Caspian Sea sub-basin waters of the three countries that border it: Iran harbors 25 species (nine genera), Azerbaijan has 28 species (10 genera), and Turkmenistan has 26 species (10 genera). The greatest known diversity of Benthophilus in South Caspian waters occurs in Azerbaijan and Turkmenistan (11 species each), whereas Iranian waters harbor seven species. In comparison, Iran, with six out of eight species (75%), has the greatest diversity of Ponticola known from the Caspian Sea basin. Species richness and endemism of the Caspian Sea gobiid-fauna varies considerably with latitude: the North, Middle and South sub-basins respectively harbor 21, 31, and 37 native species, of which 0, 3, and 10 species are endemic in that sub-basin alone. The high species diversity and endemism of Gobiidae in the South Caspian Sea sub-basin may have resulted from: (i) greater ecological diversity compared to the northern Caspian Sea marine areas (e.g., water depths) that may have led to differential niche adaptation and adaptive radiation in the Benthophilus-Anatirostrum species flock, (ii) lower historical extinction rate compared to Caspian higher latitudes, which had greater exposure to the Pleistocene's extreme climatic changes, (iii) geological history of freshwater habitats in the South Caspian Sea sub-basin that set the speciation and evolutionary stage for the genus Ponticola during these Pleistocene climatic oscillations, (iv) presently less limiting conditions compared to the North Caspian Sea, i.e., higher present winter minimum of water temperature and higher salinity, and (v) Iranian freshwater abundance, variability and habitat diversity. Contemporary gobiid diversity and endemism in the Caspian Sea basin suggests two higher-priority conservation areas: (i) freshwater habitats of the South Caspian Sea region in Iran and Azerbaijan, and (ii) shallow coastal and deep waters of the South and Middle Caspian Sea sub-basins. An identification key is provided for the updated gobiid species from the South Caspian Sea sub-basin.

A new species of tadpole-goby, Benthophilus persicus sp. nov. (Teleostei: Gobiidae) from the southern Caspian Sea.

A new gobiid species, Benthophilus persicus sp. nov., is described from the southern Caspian Sea, Iran. The new species is diagnosed by the following character states: dermal fold on cheek well-developed, large, rectangular; chin barbel 1/32/3 of eye diameter; maximum body width 15.122.9% of standard length; mouth width, 36.355.8% of head length; second dorsal fin I+78; origin of anal fin in front of vertical through origin of second dorsal fin; dermal tubercles present on body, clearly larger than granules, with two posterior rows of spinules forming an acute angle, always less than right angle; dorsal row of tubercles complete, 2229; ventral row of tubercles 2225; ventrolateral row of tubercles absent; tubercles not present on temporal and occipital head regions; granules not present on flanks; transversal suborbital row 6i below posterior end of row b; anterior interorbital transversal row pa with one or two papillae and anterior interorbital transversal papilla row pp with two or three papillae; body with 2022 transversal ltm rows starting anteriorly behind pectoral axilla and alternating anteriorly with three longitudinal llm rows.

Comparative microscopic examination of scales in 21 clupeid species from the Caspian Sea and the Indo-Pacific regions.

The clupeid fishes are large filter-feeding organisms and have diverse groups of trophic guilds and habitats. They are known for their special body scale, which is unique among the other teleost fishes. Here, we examined microscopic characteristics of scales in 21 clupeid species from four marine resources, including the Caspian Sea, the Persian Gulf and the Gulf of Oman (Indian Ocean) and South China Sea (Haian Islands and Shanwei, Pacific Ocean) to evaluate if the scale features could properly contribute to understanding the taxonomic relationships in these fishes. Typically, the studied scales were morphologically categorized into two types; circular (i.e., true circular, cordate, discoidal) and pentagonal. Also, it was found that the number and the orientation of radii and continuous striae, the presence of pores at the posterior field, overall shape, striations on the posterior field, and scale sizes could be used as suitable features to classify the clupeids in species and genus levels. The result of morphological analysis based on the scale characteristics was largely consistent with the phylogenetic relationships of the studied species. This highlighted that morphological characteristics of the clupeid scale could adequately contribute to the understanding of taxonomic relationships in this large group.