{'fraction_non_alphanumeric': 0.041653316244793334, 'fraction_numerical': 0.032788636120901424, 'mean_word_length': 5.120261437908496, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 1, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 1, 'zh_pornsignals.json': 0}}
Ichthyo-diversity in the Anzali Wetland and its related rivers in the southern Caspian Sea basin, Iran

1 Inland Waters Aquaculture Research Center, Iranian Fisheries Sciences Research Institute, Agricultural Research, Education and Extension Organization, Bandar Anzali, Iran 2 Environmental Sciences Institute, Shahid Beheshti University, Tehran, Iran 3 Department of Fisheries, Faculty of Natural Resources, University of Guilan, Sowmeh-Sara, Iran 4 The Caspian Sea basin Research Center, University of Guilan, Rasht, Iran * Corresponding author : keyvan_abbasi@yahoo.com


Journal of Animal Diversity (2019) | © Lorestan University Press
Fish identification followed Holcik (1989) and Kottelat and Freyhof (2007) using descriptive characteristics (the number of dorsal fins, type of mouth and caudal fin, oral and pharyngeal teeth, sensory organs on the head and number of barbs), meristic counts (the number of branched and unbranched rays of dorsal, pectoral, anal and caudal fins, the number of gill rakers and branchiostegal rays, lateral line scales), morphometric measurements (length and height of fins, distance between fin origins, length of head sections) and anatomical features (stomach form, the number and form of pyloric caeca, type of swim bladder and color of peritoneum).
Finally, the scientific name of each identified fish was checked against the last checklist of freshwater fishes of Iran (Esmaeili et al., 2018) and the catalogue of fishes (Fricke et al., 2019).

Results
The long-term ichthyological monitoring  confirmed the presence of 72 fish species in the Anzali Wetland and its catchment area. The fish belong to two classes the Petromyzontida, including Caspiomyzon wagneri (Kessler, 1870), and Actinopterygii (the other 71 species), 17 orders, 21 families and 53 genera. Eighteen families were recognized inside the wetland while nineteen families were present in the studied rivers (Table 1). Among the families, the Cyprinidae, Gobiidae and Clupeidae had the most diversity with 28, 13 and 4 species, respectively, while eleven families were recognized with only one representative (Table 1).
The number of fish species was approximately equal in different parts of the Anzali Wetland, except for the western part (Fig. 2). The most common species inside the wetland were from the cyprinids, followed by the gobiids (Fig. 3).
The cyprinids were also dominant in the rivers ( Among the recognized fishes, four endemic (5.56%) and 50 native species (69.44%) were identified, while 18 species (25%) are listed as exotic/alien (six of them are ornamental fish, introduced via the aquarium trade) ( Fig. 6; Appendix 2). All the identified fish species in the Anzali Wetland basin belong to seven ecological groups (Table 1, Fig. 7).

Discussion
The present study shows the fish distribution in different parts of the Anzali Wetland and its related rivers for the first time. Here, we report 72 fish species from the Anzali Wetland basin, whereas previous reports included 26 species (Gmelin, 1785;Mel'gunov, 1836;Derzhavin, 1934;Kozhin, 1957, Hydrorybproject, 1965RaLonde and Walczak, 1972), 41 species (Holcik and Oláh, 1992), 42 species (Karimpour, 1998) and 49 species (Abbasi et al., 1999). The longer sampling period, more sampled localities and the use of different fishing equipment in the present study are the main reasons for increasing the number of species. According to the obtained results, the number of exotic fishes is increasing in the Anzali Wetland in recent decades, especially due to the release of ornamental fishes through the aquarium trade.
The ichthyo-diversity of the Anzali Wetland is significantly richer than the other wetlands in the southern Caspian Sea basin, for example the Amirkelayeh Wetland with 15 species (Nezami Baluchie and Khara, 2004), Kiashahr National Park with 25 species (Khara and Nezami Baluchie, 2005), and Gomishan Wetland with 15 species (Patimar et al., 2009). The fish species richness of the wetland can be related to the permanent connection with the Caspian Sea, variable habitats, and the larger area of the Anzali Wetland in comparison with the other mentioned wetlands.
Due to the degradation of the Anzali Wetland environment, many areas were drained and others completely covered by dense aquatic plants. These changes could affect the fish diversity in different parts of the Anzali Wetland. The high sedimentation in the central and southern parts of wetland can be considered as the main reason for the low number of fishes in this region (Fig. 2).
Four freshwater species, B. cyri, O. bergianus, S. trutta and O. mykiss were only observed in the rivers and this shows their riverine dependence. Two species, A. persicus and A. stellatus were only observed in a few rivers. These are the Caspian anadromous fishes that have to pass through the corridor of the Anzali Wetland toward the rivers, but nowadays their abundance is very low in the Caspian Sea (Iran Fisheries Organization, 2017;Hashemi et al., 2019) and they are rarely observed in these freshwater regions.
In the adjacent rivers to the wetland, 23 species were previously reported by Holcik and Oláh (1992), in comparison with 53 identified fish species in the present investigation. It can be concluded that the longer sampling period with more sampling sites and various fishing techniques could have made the difference.
Nine species (particularly gobiids) are only observed in the estuarine region (Table 1) due to their main habitat in the brackish water of the Caspian Sea (Kazancheev, 1981;Abdoli and Naderi, 2009;Mirzajani et al., 2016;Abbasi, 2017), and it seems these species cannot enter the freshwater environments. Whereas A. chalcoides, A. hohenackeri, C. gibelio, R. amarus, C. saniae and P. gorlap are present in all areas inside the wetland and in almost all the adjacent rivers. Diversification of fish species in different rivers is related to ecological parameters such as length and width of rivers, water volume, type of substrate, situation of vegetation and manmade interventions such as dams and other barriers (Wootton, 1990;Rahel and Hubert, 1991). Generally more species diversity is observed in rivers which are longer in length, wider in width, lower in their slope, higher in aquatic plants (Varley, 1967;Rahel and Hubert, 1991), and also greater values of water flow and depth (Sheldon, 1968;Foltz, 1982;Adebisi, 1988). The Morghak is a short river with the least number of fish species while the Siahdarvishan is a long river with numerous streams and has the most number of fish species (Fig. 4). This pattern of ichthyo-diversity has been observed in many rivers, discharging to the southern Caspian Sea. Investigations of 20 rivers, flowing toward the southern Caspian Sea, by different authors (Ramin, 1997;Abbasi et al., 1998;2007;2011;Kiabi et al., 1999;Afraei and Lalooei, 2000;Abbasi and Sarpanah, 2001;Nazari, 2002;Abbasi, 2006a;2006b;Mostafavi, 2007;Banagar et al., 2009;Abdoli et al., 2014;Naderi Jelodar et al., 2016;Sarpanah et al., 2019) showed that the number of fish species varied from 12 to 67 species.
The freshwater resident or potamodromous species (G-I) include 34 species that exist inside the Anzali Wetland and its adjacent rivers, and are rarely observed in the estaurine region (inshore) for the purpose of feeding. According to potamodromous behavior (Acolas and Lambert, 2016), these species may move between the Anzali Wetland and its adjacent rivers to find suitable spawning grounds or feeding areas. Nowadays, as a global problem (e.g., see Lassalle and Rochard, 2009;Vignon and Sasal, 2010;Johnson et al., 2013), barriers, pollution, modification of the hydraulic regime, substrate destruction, and illegal fisheries activities along rivers cause many threats to the spawning of anadromous fish species.
Nine species (G-IV) are marine fish, observed only in the Caspian Sea and they never enter into rivers, but remain in the estuarine region for feeding and spawning. Three species (G-V) were mostly observed in the estuarine region, rarely inside the wetland and downstream of some rivers, and they spawn in both freshwater and the Caspian Sea environment. Eight species (G-VI) were mostly observed in the Caspian Sea and rarely inside the wetland but these species were not observed in rivers.
Three species (G-VII) P. gorlap, Proterorhinus nasalis and Gasterosteus aculeatus were recorded from all regions; inside the wetland, rivers and estuary in all seasons and they can spawn both in freshwater and brackish water (estuary). The European eel, Anguilla anguilla, although it is a catadromous fish species (Froese and Pauly, 2019) hitherto has been reported from the coast and not from its rivers in the southern Caspian Sea (Kazancheev, 1981;Abdoli and Naderi, 2009;Coad, 2010;2016;Keivany et al., 2016;Abbasi, 2017).
Based on the obtained results it can be concluded that 66 species (with the exception of six rare ornamental fishes) exist in different regions of the Anzali Wetland. Some of these species are rare with low abundance. Many species (20 species) belong to the Caspian Sea environment which are dependent on the Anzali Wetland due to different reasons, particularly for reproduction. Conservation of different habitats of the Anzali Wetland is necessary to preserve rare, freshwater and anadromous fish species.