INTRODUCTION AND ESTABLISHMENT OF TROPICAL ORNAMENTAL FISH , PTERYGOPLICHTHYS SPP . ( ACTINOPTERYGII : SILURIFORMES : LORICARIIDAE ) IN HOT SPRINGS : AQUARIUM TRADE AS A POTENTIAL RISK FOR BIODIVERSITY IN TURKEY

The aim of this study was to report non-native tropical ornamental freshwater fi sh species from the Pınarbaşı Stream connected with hot-water sources in the İnönü Province (Eskişehir, Turkey). The morphological characters and meristic counts indicated that the examined specimens were: Pterygoplichthys disjunctivus (Weber, 1991), Pterygoplichthys pardalis (Castelnau, 1855), and their hybrids. We also present the evidence of their reproduction and establishment. Successful invasion of these species was evident, as their young-of-the-year and juvenile individuals were caught during the samplings from the same water course. Finally, we discuss the management implications of these species.

The ornamental aquarium trade, along with the stocking for angling and aquaculture, is one of most important pathways of freshwater fi sh introduction (Gozlan 2008).Its importance, however, has been underestimated and only recently it was recognized as an important vector of aquatic invasive species (Padilla and Williams 2004, Duggan et al. 2006, Copp et al. 2007, Strecker et al. 2011).In a global perspective, the aquarium-traced introductions were reported to account for 21% of all freshwater fi sh introductions of more than 150 mainly freshwater fi shes species (Fuller 2003, Gozlan 2008).Some continents, such as North America, where hundreds of aquarium species were reported to be in circulation, have been studied more extensively (Rixon et al. 2005, Duggan et al. 2006).A good example of less studied regions is the European continent with the exception of the UK (Copp et al. 2007(Copp et al. , 2010)).Andrews (1990) reported that around 208-589 million freshwater fi sh specimens were imported to the UK between 1987and 1989. Recently, Maceda-Veiga et al. (2013) screened aquarium species composition in south-western Europe (mainly in Portugal and Spain) and found out 1133 fi sh species are on sale.
Several ornamental species, such as pond loach, Misgurnus anguillicaudatus (Cantor, 1842), have already been established in the European countries of the Mediterranean climate zone.Only three ornamental fi shes have been reported in Turkish inland waters; goldfi sh, Carassius auratus (Linnaeus, 1758); red piranha, Pygocentrus nattereri Kner, 1858; and vermiculated sailfi n catfi sh, Pterygoplichthys disjunctivus (Weber, 1991) with only goldfi sh being established (Tarkan et al. 2015).We would like to emphasize that eco-regions with hot water springs are especially susceptible for unwanted introductions (Emiroğlu 2011).
Species of Pterygoplichthys, commonly known as sailfi n catfi shes, are native to the South America.They are very popular aquarium fi shes that have been introduced into several countries on different continents such as the USA, the Philippines, Taiwan, and Turkeymainly because of their high tolerance to environmental variations and feeding behaviour, which is very effective to clean algae from submerged surfaces (Hoover et al. 2004, Chavez et al. 2006, Yalçın Özdilek 2007, Wu et al. 2011, Nico et al. 2012).
Herbivorous sailfi n catfi shes are usually successful invaders across its invasive range (Zworykin and Budaev 2013) and several factors facilitate their invasion into a variety of ecosystems.The most import are: their water pollution tolerance, low oxygen level tolerance (aided by accessory respiration), predation defence tools, such as spiny fi ns and hard external armour (Zworykin and Budaev 2013), advanced spawning behaviour (batch spawning, extended spawning period, and parental care) (Hoover et al. 2004, Liang et al. 2005).The above-mentioned advanced surviving features of sailfi n catfi shes may have negative impact on the ecosystem and the biodiversity (Hoover et al. 2004, Zworykin andBudaev 2013).Their grazing behaviour may alter the food web, especially when they become abundant (Smith 1981).They eat demersal eggs of autochthonic species and out-compete other herbivore species (Hoover et al. 2004).Also, piscivorous birds were reported to be affected by strong spines of these fi shes (Bunkley-Williams et al. 1994, Hoover et al. 2004).Their burrowing behaviour in the river banks may cause some socioeconomic problems such as the water turbidity and soil erosion.Moreover, sailfi n catfi shes also damage gillnets (Hubilla et al. 2007).Mendoza et al. (2015) using risk screening tool for freshwater fi shes (Freshwater Invasiveness Screening Kit-FISK; Copp et al. 2009) determined a high invasiveness potential for Pterygoplichthys species in Mexico.The same has been estimated for several European countries (Simonović et al. 2013, Perdikaris et al. 2016) and Turkey (Tarkan et al. 2014).In those studies, high risk of invasiveness of this fi sh was associated with its advanced reproductive features, previous history of successful introductions, detrimental impacts to the recipient ecosystems, and its environmental versatility.
In Turkey, only a single specimen of Pterygoplichthys disjunctivus was reported from the Asi River (southern Turkey) (Yalçın-Özdilek 2007).The above-mentioned author noted that this single specimen indicated potentially serious ecological problems, if the species is established, especially for rich endemic fi sh fauna of the river.However, following-up surveys found no other P. disjunctivus specimens in the river.Although the exact date is unknown, the most plausible way for Pterygoplichthys species to enter the Asi River and the hot water resources in İnönü town is the result of aquarium release or escape.Indeed, one wholesaler admitted that he released many aquarium fi shes into spring waters around İnönü town (Sakarya River Basin, north-western of Turkey) some 7-8 years ago when he went bankrupt.Our surveys have confi rmed that aquarists still damp these species and personal communications revealed that ornamental poeciliids and cichlids are purposefully being released to hot springs, because their natural water parameters are believed to be suitable for the species' survival.In addition to the introduced Pterygoplichthys spp., there are three endemic species co-habiting waters in İnönü town: Caucasian bleak, Alburnus escherichii Steindachner, 1897; Sakarya chub, Squalius pursakensis (Hankó, 1925); and Aphanius villwocki Hrbek et Wildekamp, 2003.Material and methods.Fish samples were collected from the Pınarbaşı Stream (near the town of İnönü) fed by hot spring waters.This stream originates from a rocky region in western part of the basin and joins the Porsuk River, a major tributary of the Sakarya River (39°48′48.60′′N,30°07′04.05′′E-39°49′00.08′′N30°07′53.90′′E).At the sampling site, the stream is approximately 250 cm wide, the current is slow, and the temperature is 22-26ºC throughout the year.The mean pH and mean electrical conductivity are 6.69 and 442 S • cm -1 , respectively.The water depth is between 30 and 150 cm with a muddy and plant-covered substrate.There are several artifi cial channels and weirs along the water course.Pterygoplichthys spp.occur in 1290 m long section of the stream, being most abundantly along the natural part (590 m).The stream is mainly covered by mud and submerged aquatic vegetation (Fig. 1).

Fig. 1. A section of the Pınarbaşı Stream where
Pterygoplichthys species were most abundantly caught Fish samples were collected on 09 March 2016 and 15 March 2016 with an electrofi shing device (Samus 725-PWM2).Collected fi shes were euthanized using an overdose of 2-phenoxyethanol and transported on ice to the laboratory where they were examined for morphometric characters.
The standard length and total length of the specimens were measured to the nearest mm and weighted to the nearest 0.01g.The fi sh were macroscopically examined and photographed.Some meristic characters such as the number of branched fi n rays of dorsal, pectoral, and ventral fi ns were counted.The specimens were identifi ed using taxonomic keys of Weber (1991Weber ( , 1992) ) and Armbruster and Page (2006).All the counts and measurements were done according to Weber (1992), which largely follows Boeseman (1968) except the following ratios: head width ÷ distance between posterior eye margins, head depth ÷ head depth through eye.Other morphological characters were identifi ed according to the description of Armbruster and Page (2006).A recent key on the web page of Armbruster * was used to verify the measurements.Species of the genus Pterygoplichthys can be easily distinguished from other loricariids by the following characters: presence of a short adipose fi n, dorsally and laterally plated body, more than 10 teeth per jaw ramus, eight or more branched dorsal fi n rays.Results.The number of Pterygoplichthys individuals observed was about 400 in approximately 300 m stretch of the stream.This was the most abundant section of the area studied, in terms of the presence of those fi sh.This suggests high abundance of the species in this water course.The following characters indicated that examined species were the members of genus Pterygoplichthys: supraoccipital fl at or rounded, not forming a median crest, a single buccal papilla, short odontodes on lateral plates, without hypertrophic odontodes on check plates, abdomen with dark spots on light background, dark spots often coalescing to form vermiculations.).The morphometric and meristic characters of the fi sh studied are presented in Table 1.
The performed morphological analysis (Table 1) given below showed that our specimens belong to Pterygoplichthys pardalis (Castelnau, 1855), Pterygoplichthys disjunctivus, and their hybrids.The main distinguishing characters between P. pardalis and P. disjunctivus are the design and pigmentation pattern of abdomen.Pterygoplichthys disjunctivus differs from P. pardalis by having dark spots on the abdomen coalesced to form vermiculate pattern, whereas P. pardalis abdomen is covered with discrete spots.The specimens having a design pattern other than these two pattern were considered hybrids (Fig. 2).Notably, we found a wide inter-species variation in the design pattern.The meristic characters were also important to verify the genus, the branched fi n rays of 22 specimens were counted, the number of dorsal fi n rays were from 11 (number of individuals, n = 4) to 13 (n = 1), mostly 12 (n = 18), whereas for pectoral rays varied between 5 (n = 8) and 7 (n = 1), mostly 6 (n = 14) and ventral rays between 4 (n = 11) and 5 (n = 12).
The majority of the characters of hybrids seemed to be closer to P. disjunctivus than P. pardalis.Many meristic characters such as head length, maximum body depth, and caudal peduncle height have smaller mean values in hybrids.Hybrids apparently differed from the P. pardalis and P. disjunctivus by having smaller eye diameter, smaller head depth, narrower caudal peduncle, shorter head, and lower maximum body depth.
The standard, total length, and weight of all examined specimens amounted to 10.9-35.1 mm, 15.8-43.3mm, and 24.0-647.5 g, respectively.We dissected 9 specimens and found that all the dissected specimens were females, among those specimens 5 had ripening eggs in ovaries, others with ovaries in developing or resting stage.One of the ovaries was signifi cantly smaller than the other (Fig. 3).
Pterygoplichthys species were observed to prefer consistently dense vegetation on the bottom of the water course and avoid rocky microhabitats.Young-of-the-year and juvenile individuals of fi sh species under study were caught during the samplings from the stream, indicating their successful invasion.Further, we found that the crevices along the lateral walls of the water course were used by Pterygoplichthys spp.for laying their eggs.Remarks.Our morphological analyses on the collected specimens from the stream (in İnönü town) fed hot spring water indicated that non-native Pterygoplichthys species should be identifi ed as P. disjunctivus and P. pardalis or their hybrids.Indeed, identifi cation of Pterygoplichthys species is highly complicated because of intra-specifi c variation and likely natural and artifi cial hybridization (Hoover et al. 2004, Wu et al. 2011, Nico et al. 2012).Previous genetic-based identifi cation studies explain this diffi culty and usually found almost no genetic difference between these species (Wu et al. 2011, Bijukumar et al. 2015).The identifi cation of the specimens in the presently reported study followed Weber (1991Weber ( , 1992)), Armbruster and Page (2006), Chavez et al. (2006), andWu et al. (2011).All showed that the main distinguishing character between P. disjunctivus and P. pardalis is that the former has reticulate dark pattern on the ventral surface while the later has a spotted pattern.It is worth noting that our specimens have abdomen design pattern that closely resembles that of P. disjunctivus as shown by Wu et al. (2011).However, Armbruster and Page (2006) noted that adult P. disjunctivus do not have geometric patterns on the head while our specimen does, suggesting that it is a hybrid or a specifi c variation.This can be confi rmed more clearly by the key in the website on the Loricariidae by Jonathan Armbruster * .
Given that Pterygoplichthys species have been widely reported to severely impact native biota, our fi ndings on the fi rst abundant and reproducing established populations of these species in Turkey should have very important management implications.In particular, hybrid specimens found in relatively higher numbers should be carefully monitored, as previous reports clearly indicated that the superiority of the hybrid might have helped increase its fi tness during population invasions (Wu et al. 2011).It is obvious that the springs and spring runs where Pterygoplichthys species have been caught in the presently reported study serve as thermal refuges in winter for these tropical fi shes however their high abundances and wide distribution may lead to displace the native fi sh and endemic species that are found in the same water course and disturb ecosystem structure and services.
Bio-ecological features, reproductive traits, environmental tolerances and possible ecosystem impacts of Pterygoplichthys species should continuously be monitored in these spring water sources to determine risk levels and management actions of the species.Thermal refuge condition of the region and strong habitat preferences of the species (i.e., abundant vegetative microhabitats) may also  Pterygoplichthyes disjunctivus (middle), and a hybrid of these species (bottom) provide an opportunity to properly eradicate these species, which warrants further studies.It should be noted that deciding an eradication or control program requires the information on vulnerability of the habitats, propagule pressure, interconnectivity with source population and available funds along with the knowledge of impacts and biology of the non-native species (Hill and Sowards 2015).

Fig. 3 .
A Pterygoplichthys individual with ripening eggs * See footnote on page 553.