Establishment of non-native guppy Poecilia reticulata (Peters, 1859) (Cyprinodontiformes: Poeciliidae) in an Municipal Park located in Minas Gerais State, Brazil THIAGO D. OLIVEIRA1, ALESSANDRA C. REIS2, CAMILA O. GUEDES1,†, MARIANA L. SALES1, EDUARDO P. R. BRAGA3, THIAGO F. RATTON1, BRUNO P. MAIA1 & ANDRÉ L. B. MAGALHÃES4 1 Centro Universitário UNA, Instituto de Ciências Biológicas e da Saúde. Rua Guajajaras, 175, CEP: 30180-100, Belo Horizonte, MG, Brazil. † In Memorian. 2 Universidade Federal de Minas Gerais, Programa de Pós-Graduação em Biologia Celular (PPG-BC). Av. Antônio Carlos, 6627, CEP: 31270-901, Belo Horizonte, MG, Brazil. 3 Universidade Federal do Rio Grande, Curso de Pós-Graduação em Oceanografia Biológica. Av. Itália Km 8, CEP: 96203-900, Rio Grande, RS, Brazil. 4 Pontifícia Universidade Católica de Minas Gerais, Programa de Pós-Graduação em Zoologia de Vertebrados. Av. Dom José Gaspar, 500, CEP: 30535-610, Belo Horizonte, MG, Brazil. E-mail: andrebiomagalhaes@gmail.com Abstract. We evaluated the establishment of the ornamental non-native guppy Poecilia reticulata bimonthly from November 2006 to October 2007 in an urban reservoir located in the city of Belo Horizonte, Southeastern Brazil. Females were found in reproduction during almost all the sampling period. The fecundity was always low. For the total period, we found more females than males, and the number of juveniles in all periods was higher than adults. There was no correlation between water temperature, rainfall and reproduction. Of the five stages of biological invasion, the species was at least in the stage three: establishment through reproduction and recruitment. Management recommendations, such as prohibition on sales of P. reticulata by local aquarium trade, and awareness campaigns with wholesalers, retailers and hobbyists showing that aquarium dumping is an environmental crime are suggested to avoid introductions of P. reticulata in the region. Key words: aquarium dumping, biological invasions, poeciliids, reproduction, sex ratio Resumo. Estabelecimento do peixe não-nativo guppy Poecilia reticulata (Peters, 1859) (Cyprinodontiformes: Poeciliidae) em um parque municipal localizado no estado de Minas Gerais, Brasil. Avaliamos bimestralmente de Novembro de 2006 a Outubro de 2007 o estabelecimento do peixe ornamental não-nativo guppy Poecilia reticulata em um reservatório urbano localizado na cidade de Belo Horizonte, sudeste do Brasil. Fêmeas foram encontradas em reprodução durante todo o período amostral, e a fecundidade foi sempre baixa. Para o período total, foram encontradas mais fêmeas que machos, e o número de juvenis em todos os períodos foi maior que o de adultos. Não houve correlação entre a temperatura da água, precipitação pluviométrica e a reprodução de P. reticulata. Dos cinco estágios de invasão biológica, P. reticulata estava pelo menos na fase três: estabelecimento através de reprodução e recrutamento. Recomendações como proibição de venda de P. reticulata pelo comércio local e campanhas de conscientização com fornecedores, lojistas e aquaristas mostrando que o abandono de peixes de aquário em ambientes naturais é considerado crime ambiental são sugeridas para evitar a introdução de P. reticulata na região. Palavras chave: poecilídeos, invasão biológica, aspectos reprodutivos, Lagoa do Nado, sudeste do Brasil Pan-American Journal of Aquatic Sciences (2014), 9(1):21-30 22 Introduction Among the Brazilian states, Minas Gerais is the fourth largest, with an area of 586,528 Km 2, and a growing population of about 20 million people living in 853 cities (IBGE 2002). The state is drained by 17 watersheds (IGAM 1998), with thousands of creeks and more than 2,000 dammed water bodies of different sizes (Alves et al. 2007). The native ichthyofauna of the state, comprising 354 species (Alves et al. 2007), of which 49 species are considered some of the country´s most threatened fishes (Fundação Biodiversitas 2007). All these species are likely to be seriously endangered, since Minas Gerais State ranks first in fish introductions not only in Brazil but in South America, with 85 non-native species, 65 of which ornamental (Magalhães & Jacobi 2013). The ornamental guppy Poecilia reticulata is one of the 85 non-native fish found in inland waters of the state. It is a small live-bearing (i.e., ovoviviparous) cyprinodontiform native to the Caribbean Islands (Netherlands Antilles, Trinidad and Tobago, Barbados, Windward and Leeward Islands), Venezuela, Guyana, and northern Brazil (Amapá and Pará States) (Lucinda & Costa 2007). Males grow about 3.5 cm in length and they have their anal fin modified into a gonopodium, while females are larger (up to 5.0 cm) (Froese & Pauly 2011). They feed on zooplankton, invertebrates and algae (Rocha et al. 2009) and prefer slow-flowing warmwater habitats (Froese & Pauly 2011). Guppies are among the most popular in the aquarium trade of Minas Gerais (Magalhães & Jacobi 2013), and they are introduced into water bodies in the city of Belo Horizonte through the aquarium dumping (Godinho et al. 1992, Chaves & Magalhães 2010). Despite introduced throughout Minas Gerais State (Alves et al. 2007), several features of the lifehistory of P. reticulata are not well-studied, including essential ones such as reproductive biology and population structure, which are needed to understand the invasion of this species in new environments. Thus, the aim of the present study was to help filling in this gap, with special focus on the reproductive cycle, fecundity, sex ratio, juvenileto-adult ratio, reproduction and abiotic factors and the process of invasion of guppy in an urban reservoir located in the city of Belo Horizonte. We also suggest management actions to prevent further introductions in the region. T. D. OLIVEIRA ET AL. Material and Methods Study area The Lagoa do Nado (19o49’56”S; 43º57’34”W), is a small meso-eutrophic reservoir located in the city of Belo Horizonte, Minas Gerais State, Southeastern Brazil (Figure 1). The superficial area of the lake is 1.5 ha, and the mean depth is 2.7 m. The native fish fauna is represented by species from the São Francisco River Basin such as the piabas Hyphessobrycon santae, Hasemania nana, chameleon cichlid Australoheros facetum, pearl cichlid Geophagus brasiliensis, cascarudo Callichthys callichthys, suckermouth catfish Hypostomus sp.. Non-native fishes include guppy P. reticulata, giant trahira Hoplias cf. lacerdae, and Nile tilapia Oreochromis niloticus (Braga 2010). This reservoir is located at the Fazenda Lagoa do Nado Municipal Park, a unit of conservation created in 1994 with the purpose to increase the human interaction with natural areas (Mafia et al. 2012). Due to the proximity of Lagoa do Nado reservoir with two densely populated neighborhoods (Bairros de Belo Horizonte 2010), the introductions of P. reticulata was most likely caused by aquarium hobbyists discarding the species (Chaves & Magalhães 2010). Sampling design We collected a total of 1,536 juveniles (0.50.9 cm total length), 700 females (1.0-2.1 and 2.23.3 cm standard length) (a random subsample of 366 females only to study macroscopic/mesoscopic developmental stages and the reproductive cycle), and 427 males (1.0-2.0 and 2.1-2.5 cm standard length) of P. reticulata every two months; from November 2006-October 2007 using sieves (50 cm long, 30 cm high, and 0.2 mm mesh) in a sampling site nearby the dam. The fishes were euthanized on an ice slurry, a method approved for field work by IACUC (2002), packed in plastic bags, fixed in 10% formalin, and subsequently transferred to 70% alcohol. In the laboratory, the species was sexed as juveniles were smaller than the smallest male, females in the case of the absence of gonopodia but were larger than the smallest male and as males if they possessed any evidence of a gonopodium (Fernandez-Delgado & Rossomanno 1997). Abiotic data were collected bimonthly, namely water temperature and rainfall (Table I). The first data were obtained at the times of the fish sampling. We measured water temperature in the field with a Pan-American Journal of Aquatic Sciences (2014), 9(1):21-30 Reproduction of Poecilia reticulata 23 thermometer to the scale 0o to 50oC. Rainfall data are from the database of the 5 th Meteorological District (Instituto Nacional de MetereologiaINMET) located in the city of Belo Horizonte. Figure 1. Map showing sampling location of non-native Poecilia reticulata in North region of the city of Belo Horizonte. MG= Minas Gerais State, BH= city of Belo Horizonte, ●= sampling site in Lagoa do Nado reservoir, UTM coordinates. Developmental stages Macroscopically, we classified as nongravid females those without a conspicuously enlarged ventral region, absence of gravid spot near the base of the anal fin, eggs or embryos. Females with enlarged bellies, presence of gravid spots, eggs, or embryos seen with the naked eye were classified as gravid according to Winemiller (1989). We adapted the methods of Shahjahan et al. (2013) to determine under the binocular stereomicroscope the developmental stages of reproductive females. Stages were classified as follows: 1) Non-gravid (ovarian tissue without ovum and/or embryos), 2) Early-yolked ovum (orange ovum in the process of yolking), 3) Early-eyed embryos (pigmented eyes, enlarged head compared to trunk, presence of caudal and pectoral fin buds, orange yolk), and 4) Mature embryos (yolk sac mostly or completely absorbed, elongate pectoral fins, presence of scales, embryo resembling a small adult) (Figure 2). After determining the developmental stages, the bimonthly absolute and relative frequencies of females were calculated. Table I. Mean values of abiotic factors bimonthly in Lagoa do Nado reservoir between November 2006 and October 2007. Water temperature (oC) Rainfall (mm) November-December 26.9 447 January-February 27.4 278.9 March-April 29.3 93.3 May-June 26.2 10.2 July-August 25.4 0 September-October 28.5 2 Bimesters Pan-American Journal of Aquatic Sciences (2014), 9(1):21-30 24 T. D. OLIVEIRA ET AL. Figure 2. Macroscopic (left column) and mesoscopic (right column) developmental stages of Poecilia reticulata females. 1) Non-gravid (Asterisk: ovarian tissue without ovum or embryos), 2) Early-yolked ovum, 3) Early-eyed embryos, 4) Mature embryos. Scale bars (left column: 1 cm, right column: 20 ×). Fecundity We estimated the bimonthly and total mean values of fecundity (developmental stages 2, 3 and 4) of P. reticulata in the Lagoa do Nado reservoir. Fecundity was determined from early-yolked ovum or embryos in the ovaries, and they were counted under the binocular stereomicroscope according to Öztürk & Ikiz (2004). Population structure The sex and juvenile-to-adult ratio (Pope et al. 2010) were calculated from the bimonthly and total number of females, males and juveniles of P. reticulata. Correlation between reproduction and abiotic factors Following Andrade & Braga (2005), we grouped the bimonthly relative frequencies of gravid females (stages 2, 3, 4), which were then correlated with the average bimonthly water temperature and rainfall. Statistical analysis The fecundity values were compared using one-way ANOVA, followed when necessary by a Tukey pos-hoc test to determine significant differences between mean values. Chi-square (χ2 test) was used to check the differences in proportions between sexes and juveniles-to-adults, and the Spearman’s rank correlation (r) to test a relationship between female reproduction and abiotic factors (Sokal & Rohlf 1995). Differences were considered significant for P<0.05. All statistical analyses were performed using PASTPaleontological Statistics (version 1.91) software (Hammer et al. 2009). Results Females were found in several developmental stages (stages 2, 3, 4) during almost all the sampling period (Figure 3). Mean fecundity was low in all bimesters with no statistical differences while for the total period, there was a statistical difference between developmental stages 2 and 3. The lowest fecundities were observed in September-October 2007 with mean value of 3.5 (±2.12), while for the whole study period the mean value was 6.22 (±2.06) (Table II). We found more females than males in November-December 2006, January-February 2007 Pan-American Journal of Aquatic Sciences (2014), 9(1):21-30 Reproduction of Poecilia reticulata 25 and May-June 2007. Overall, females were more frequent than males (χ2=66.12, 1.64, df=1, P<0.05) (Table III). The number of juveniles in all periods was higher than adult females and males (χ2=62.82, 100% 3 13 Frequency 80% 28 df=1, P<0.05) (Table IV). Water temperature and rainfall were not significantly correlated with reproduction in females (r=0.486, P=0.33; r=-0.143, P=0.79) (Table V). 2 4 3 7 31 13 1 8 23 60% 5 2 4 3 2 1 19 33 40% 5 49 42 25 20% 21 4 J-F M-A 25 0% N-D M-J J-A S-O Figure 3. Relative bimonthly frequency of developmental stages in Poecilia reticulata females captured in Lagoa do Nado reservoir between November 2006 and October 2007. Developmental stages: 1) Non-gravid, 2) Early-yolked ovum, 3) Early-eyed embryos, 4) Mature embryos. Table II. Bimonthly and total fecundity of Poecilia reticulata females captured in Lagoa do Nado reservoir between November 2006 and October 2007. Developmental stages: 2) Early-yolked ovum, 3) Early-eyed embryos, 4) Mature embryos. In a row, same letters indicate no significant differences (P<0.05). Bimesters Developmental stages 3 3.67±2.08a November-December 2 6.54±7.00a 4 - January-February 4.79±2.04a 6.61±3.43a 4.85±3.53a March-April 7.4±7.37a 12.71±13.63a 9.5±9.19a May-June 4.19±3.39a 4.33±3.21a 6.25±3.59a July-August 9.62±8.22a 14.67±6.93a 12.5±14.85a September-October Total 4.79±2.53a 6.22±2.06a 3.5±2.12a 7.58±4.90b 5.0±2.24a 6.35±4.29ab Pan-American Journal of Aquatic Sciences (2014), 9(1):21-30 26 T. D. OLIVEIRA ET AL. Table III. Bimonthly and total sex ratio of Poecilia reticulata captured in Lagoa do Nado reservoir between November 2006 and October 2007. *Significantly different (P<0.05), χ20.05=3.84, df=1. Bimesters November-December Females 272 Males 146 Chi-square 37.98* January-February 167 108 12.66* March-April 35 47 1.76 May-June 163 70 37.12* July-August 21 19 0.1 September-October Total 42 700 37 427 0.32 66.12* Table IV. Bimonthly and total juvenile-to-adult ratio of Poecilia reticulata captured in Lagoa do Nado reservoir between November 2006 and October 2007. Juv=Juveniles, Fem=Females, Mal=Males. *Significantly different (P<0.05), χ20.05=3.84, df=1. Bimesters NovemberDecember Juveniles 0.5 0.9 Total cm cm 282 288 570 Females 1.0-2.1 2.2-3.3 cm cm 92 180 Total 272 Males 1.0-2.0 2.1-2.5 cm cm 26 120 Total Chi-square (Juv-Fem+Mal) 146 23.24* JanuaryFebruary 146 138 284 34 133 167 30 78 108 0.14 MarchApril 20 107 127 10 25 35 26 21 47 9.68* MayJune 244 160 404 143 20 163 18 52 70 45.9* JulyAugust 33 7 40 5 16 21 9 10 19 0.00 SeptemberOctober Total 81 30 111 11 31 42 23 14 37 5.38* 806 730 1,536 295 405 700 132 295 427 62.82* Table V. Spearman’s rank correlation (r) between Poecilia reticulata females and abiotic factors in the Lagoa do Nado reservoir between November 2006 and October 2007. Variables Gravid females × Water temperature r 0.486 P 0.33 Gravid females × Rainfall -0.143 0.79 Pan-American Journal of Aquatic Sciences (2014), 9(1):21-30 Reproduction of Poecilia reticulata 27 Discussion Studies about the reproductive biology of P. reticulata outside their natural ranges are essential to assess their degree of establishment, spread and potential ecological impacts on native communities in Minas Gerais (Magalhães 2008). We found females of P. reticulata in reproductive activity during the 12 months of the study period. A prolonged reproducive period was also found for the same species in a small impoundment in Cuba and in concrete channels in Pará State, Brazil (Koldenkova et al. 1990, Montag et al. 2011). Frequent reproduction over an extended breeding season is an opportunistic life-history strategy adopted by guppies that permit effective colonization in humanaltered habitats (Gratwicke 2000). The fecundity observed for the species was low. Low fecundity was also observed in P. reticulata introduced in Costa Rica (Hernández et al. 2004). This characteristic may be probably due to larger size of embryos, a common reproductive feature for this fish (Reznick & Endler 1982), which may result in a higher probability of survival in new habitats (Gordon et al. 2009). The majority of fish populations are expected to maintain a 1:1 sex ratio since the probability of occurrence for each sex should be 50%. When this proportion does not hold, the reasons and their consequences for population growth should be investigated (Pope et al. 2010). A higher frequency of females (female-biased sex ratio), was found in P. reticulata. This trend was also found for this poeciliid in Colombia and São Paulo State, Brazil (Garcia et al. 2008, Andrade et al. 2008). In poeciliids, males are more susceptible to mortality from a variety of sources, including differential predation due to their bright colours, higher susceptibility to stressors such as extreme temperatures, overcrowding, hypoxia, and also accelerated aging, since they invest their energy exclusively on mating behaviors (Snelson 1989). The advantage of having more females in P. reticulata is that they do not depend on the constant presence of males to reproduce because they can store sperms for later fertilization and may produce 20-40 live young every four weeks (Froese & Pauly 2011), attributes that allow them to be able to colonize any environment (Deacon et al. 2011). The number of P. reticulata juveniles was higher than adults. The same characteristic was found for P. reticulata introduced in Rio de Janeiro State, Brazil (Araújo et al. 2009). A large ratio of juveniles to adults is an indication of successful recruitment, and a fish population with recruitment difficulties will be characterized by fewer juveniles relative to adults (Pope et al. 2010). The lack of correlation between abiotic factors was already expected. This has been explained by ovoviviparity, a common reproductive strategy of the studied species (Snelson 1989). Since eggs and embryos develop inside the female’s body, they are less influenced by several external conditions such as temperature variations, rain, acidity, turbidity, salinity, diseases and predators attack (Nakatani et al. 2001). According to Lockwood et al. (2007), the process of invasion by a non-native species occurs in five stages: 1) transportation from the place of origin; 2) arrival in the new environment; 3) establishment, when an immigrant population is maintained by reproduction and juvenile recruitment; 4) spread, when a population expands its geographic range; 5) low to high impact, when the receiving biota is affected by non-native species, and thus earn the name “invasive”. The year-round presence of reproductive females and juveniles suggests that P. reticulata is established and probably expanding its population in Lagoa do Nado reservoir. Another evidence of establishment is the alteration of phenotype "store-bought type" (males are brighter and have larger colorful tails, females are plainer in color and have a smaller colorful tail) available in local aquarium trade to “wild-type”. All of those that were collected in the present study resembled the “wild-type” in which adult males are grey with some coloured spots on the body and a translucent small tail, while females are dull brown (André Lincoln Barroso Magalhães, pers. obs.). These observations agree with the statement of Reznick & Bryga (1987) that when guppies are transplanted from one environment to another, the new phenotype evolves rapidly. Thus, and considering the highly competitive and destructive nature of this species worldwide and in Brazil (Courtenay & Meffe 1989, Vieira & Shibatta 2007, Cunico et al. 2009), this livebearer probably will reach the fifth stage of the process of biological invasion in this man-made lake. The nest-guarding cichlids such as Australoheros facetum, Geophagus brasiliensis and the calictiid Callichthys callichthys will probably be unaffected by it, but other native species that do not guard their eggs (e.g., Hyphessobrycon santae, Hasemania nana) could be adversely affected. Due to the environmental problem detected in this study (i.e., establishment of an non-native fish), and the few strategies in Belo Horizonte and Minas Gerais to combat non-native aquatic species (Magalhães & Jacobi 2013), we recommend: a) the prohibition on sales of P. reticulata by local aquarium stores, b) a program for returning Pan-American Journal of Aquatic Sciences (2014), 9(1):21-30 28 unwanted fishes to aquarium stores can be effective in order to stop new aquarium-fish introductions, c) display warning informing about the negative ecological effects of aquarium dumping in all fish plastic bags and website of the aquarium store, and d) continuous awareness campaigns with wholesalers, retailers and aquarium hobbyists showing that abandonment of pets (i.e., aquarium dumping) is an environmental crime with a penalty of detention and fine, according to the Federal Law No. 9605 of 1998. Concluding, these management recommendations are not intended to harm the activities of aquarium trade, given its undeniable economic importance to the city of Belo Horizonte. However, if these precautionary measures are not implemented, the propagule pressure due to releases of P. reticulata will continue, causing low resilience in Lagoa do Nado reservoir and permanently threatening native species in this ecosystem. Acknowledgements The authors are grateful to the Centro Universitário UNA (Institute of Education, Research and Extension) for financial support (BIC #52006/2007), to Instituto Estadual de Florestas de Minas Gerais (IEF-MG #068/2006) for granting permission to collect the fishes, to 5th Meteorological District (INMET) for rainfall data, and to Sérgio Augusto Domingues (Director, Fazenda Lagoa do Nado Municipal Park) for your assistance during this study. References Alves, C. B. M., Vieira, F., Magalhães, A. L. B. & Brito, M. F. G. 2007. 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