Record of morphological deformities in Corydoras aff . longipinnis in two reservoirs under urban influence in Upper Iguaçu and Southern Coastal basins in Paraná State , Brazil

In this work we report on the presence of morphological deformities in Corydoras aff. longipinnis from two reservoirs in Paraná State, Brazil. The frequency of deformities in the fish populations was 11% in Iraí and 10.5% in Capivari reservoirs. Considering that the frequency may be associated with impacts caused by anthropic activities, this information can be used as a metric in management systems and environmental monitoring.


Introduction
Deformities in aquatic organisms are widely used as an environmental indicator, and their presence are related to several anthropic impacts (Sanders et al. 1999, Sun et al. 2009, Flores-Lopes & Reuss-Strenzel 2011).These deformities can originate from a direct interference in the organisms development caused by chemical compounds (such as heavy metals), or can be result of environmental changes due to anthropic activities that decreases population size favoring endogamy (Reash & Berra 1989;Sánchez et al. 2011, Messaoudi et al. 2009).In addition, environmental changes can make populations susceptible to parasites, cause parasite populations to increase, or cause intermediate host populations to increase.The resulting increase in parasitic infestation can cause diseases which in turn result in morphological deformities (Cunningham et al. 2005, Johnson et al. 2007).
Morphological deformities registered in Neotropical fish comprise dysplasia (atrophy, hypertrophy, torsion, deformation) on opercular bones, maxilla-mandibular apparatus, branchiostegal bones, fins and eyes.Also, tumors (neoplasias) on bones and skin and deformations on vertebral column (kyphosis, lordosis and scoliosis) can be observed (Flores-Lopes & Reuss-Strenzel, 2011).The occurrence of these morphological conditions coupled with other metrics, such as proportion of taxonomic groups, quantity of tolerant species, trophic position of species, fluctuating asymmetry, and the fish health, are present in many environmental assessments (Jaramillo-Villa & Caramaschi, 2008;Flores-Lopes et al. 2010).
The present work sought to register, identify, illustrate and quantify the morphological abnormalities in Corydoras aff.longipinnis from two reservoirs under urban influence.Since the occurrence of deformities in this species have been registered in polluted waters (Malabarba et al. 2004;Flores-Lopes & Reus-Strenzel 2011), the importance of this kind of evaluation in environmental assessments can be highlighted considering that poor environmental conditions can be related to occurrence of deformities.

Material and Methods
The two studied reservoirs are Iraí and Capivari, respectively located in the upper Iguaçu and Southern Coastal river basins, Paraná State, Brazil.The Iraí reservoir is located in the metropolitan area of Curitiba (25º24'33"S 49º6'16") and is used for water supply (Rodrigues et al., 2005).The Capivari is located 50 km from Curitiba (25º10'46"S 48º52'51"W) and its water is used by a hydroelectric plant (Parigot de Souza power plant) (Rodrigues et al., 2005).Both reservoirs are located in the Atlantic forest biome, presenting fragments of semideciduous ombrophilous forest, and araucaria forest (Maack, 2012).
The fish were collected in 2002, using cast nets and trawl nets, fixed in formaldehyde 10% and conserved in alcohol 70 o GL.Species identification followed Tencatt et al. (2016).Each individual was examined using a visual method to identify morphological abnormalities, following Flores-Lopes & Reuss-Strenzel (2011).The frequency of deformities was calculated based on the number of abnormality occurrences relative to the total number of individuals.The use of the number of occurrences instead of the number of individuals with abnormalities was adopted because some individuals presented more than one abnormality. Examined
As previously discussed, most morphological deformities are related to negative anthropogenic influences on the environment (Sanders et al. 1999).An evaluation of water quality in the studied reservoirs, assessed from 2005 to 2008 classified Iraí as critically degraded (or polluted) and Capivari as moderately degraded (Instituto Ambiental do Paraná, 2009).In the same document, sewage discharges and industrial activities were also recorded from tributaries, resulting in an increase of nutrient concentrations in Capivari reservoir and consequently a decline in water quality.
More accurate analysis could elucidate which factors are responsible for the morphological deformities reported.Considering the industrial activities and sewage discharges, the presence of heavy metals and other kinds of pollutants, such as pesticides can be designated as potential causes of the deformities that were found.
Comparisons between populations found in conserved locations and those collected from polluted locals, can contribute to verify the natural frequency of occurrence of deformities in fish populations.Messaoudi et al. (2009) verified that polluted locals presented a frequency of deformities three times greater in relation to unpolluted areas.However, this comparison was made in marine environment, using other species.In Neotropical region, C. aff.longipinnis from the Guaíba lake, which is under urban influence, (≈ 6.9%) is at least two times proportionally higher than in the Guaíba Lake (≈ 1.3-3.1%).The use of Iraí and Capivari reservoirs for human activities, such as water supply, energy generation, fishing, and recreation, emphasizes the importance of conducting proper environmental monitoring in these water bodies, since deformities in fish could indicate low water quality and presence of harmful substances.These statements highlight the use of fish as a potential biological indicator, but there is a need for more detailed analysis concerning the specific cause of deformities.Encouraging further survey efforts is essential to improve the monitoring and assessment of aquatic environments.

Table 1 .
Number of occurrences and frequency of deformities in Corydoras aff.longipinnis sampled in the Iraí and Capivari reservoirs.