The non-native goby Padogobius bonelli in the River Tiber, Italy and its effect on the reproductive potential of the native goby, P. nigricans (original) (raw)
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Hydrobiologia, 2016
The introduced goby Padogobius bonelli has established abundant populations in the River Tiber basin (Central Italy) and its expansion coincided with the decrease of the endemic P. nigricans. P. bonelli exhibits a more aggressive behaviour than P. nigricans, but other biological attributes may advance its colonization success. To test this hypothesis, some reproductive parameters (gonado-somatic index, age at maturity, egg size, absolute and relative fecundity) of a long-time established non-native population of P. bonelli were analysed and compared to a population from the native area as well as to those of P. nigricans inhabiting the same river. As a result, no differences between non-native and native populations of P. bonelli were observed. On the contrary, non-native P. bonelli showed higher values of gonado-somatic index for both sexes, a more protracted spawning season and produced a greater number of eggs than P. nigricans. These results indicated a greater reproductive output of P. bonelli that can enhance its invasion process and favour the expansion outside of its native range, causing further decline of P. nigricans populations.
Journal of Applied Ichthyology, 2015
In this study, data of Padogobius nigricans, a species endemic to Central Italy, were used to assess the age, growth parameters and condition of this species. Length-weight relationships are also provided and represent the first available reference in the literature for the Arno goby. Data were collected in the Aggia River, a tributary of the Tiber River, by monthly samplings. A total of 780 specimens ranging in size from 1.5 to 9.2 cm were analyzed. Age was assessed by examination of scales, with the maximum age of 4+ years observed in males and 3+ in females. Previous growth was determined by back-calculation of scale measurements. The von Bertalanffy growth parameters were estimated separately for sexes (males: L ∞ = 9.759 cm, k = 0.505, t 0 = 0.025, Ф 0 = 1.682; females: L ∞ = 8.989, k = 0.458, t 0 = 0.028; Ф 0 = 1.599). Evidence of growth differences between sexes was found, with males living longer and reaching larger sizes. Using the relative condition factor, condition was lower in females than in males, especially during the breeding period due to the strain of high reproduction. Competition with the congeneric P. bonelli, a species endemic to Northern Italy that was introduced in Central Italy, seems not to have been disadvantaged directly by the growth of P. nigricans in the Aggia River, since no selective size-mortality occurred in the population.
Journal of Applied Ichthyology, 2011
The reproductive biology and gonadogenesis cycle of the Vrgorac goby, Knipowitschia croatica is described [Conservation of Endangered Freshwater Fish in Europe, Birkhauser Verlag, Basel]. The species displays sexual dimorphism during the spawning period. Sexual maturity is achieved at an early age, with 50% of males and females sexually mature at total lengths of 40-45 mm. Fecundity of gravid females ranged from 188 to 593 eggs, with an egg diameter of 0.22-1.11 mm. Though the extended spawning period lasts from March to November, the highest intensity is observed from April to September. A comparison is made of the reproductive biology of this species with other sand goby species of the genera Knipowitschia and Pomatoschistus.
Acta Ichthyologica et Piscatoria
Background. In Europe, the western tubenose goby, Proterorhinus semilunaris (Heckel, 1837), is the smallest and one of the most expansive species among invasive Ponto-Caspian gobies. The aim of the presently reported study was to investigate reproductive parameters of the tubenose goby population from the Vistula River, as one of the biological traits that might facilitate its successful invasion. Materials and methods. Fish were sampled monthly from March through October and the following parameters were determined: sex ratio, gonadosomatic index (GSI), fecundity (absolute, relative, batch), oocyte size distribution, and body condition (Fulton's and Clark's indices). Results. GSI varied considerably between sexes and between individual spring months. The increase of GSI and oocyte diameter distributions indicated that spawning of P. semilunaris in the Vistula River lasted from the end of April till July. Multimodal oocytes distribution during reproductive season suggested at least two or three spawning events. The absolute fecundity ranged from 504 to 1250. The mean batch fecundity (± standard deviation) was 338.35 ± 89.22. Both, the absolute and batch fecundity, but not the mean oocyte diameter in the batch, were related to the female standard length. The highest values of Fulton condition index were observed in the reproductive period compared to pre-and post-spawning, while Clark condition index showed a different pattern. Conclusion. The western tubenose goby displays reproductive strategy typical for other fish invaders that successfully naturalized in central Europe.
Round goby (Neogobius melanostomus Pallas, 1811) potential to reproduce in fresh water
Journal of Ichthyology
The results obtained indicate the potential of the round goby to reproduce in fresh water, which may result in further expansion of the species to upper reaches of rivers and to other water bodies (lakes, dam reservoirs). Embryonic development of the round goby in fresh water proceeded in a regular manner. However, embryonic development in fresh water took a shorter time than in saline water. Although the newly hatched larvae were somewhat smaller than those hatching from eggs kept in saline water, the hatching rate was high (90%). If the species finds conditions suitable for reproduction in Polish freshwater bodies, it may pose a threat to numerous native freshwater fish species by taking over both their feeding and reproductive niches.
Transactions of The American Fisheries Society, 2000
The round goby Neogobius melanostomus successfully invaded the Great Lakes perhaps, in part, because of its reproductive strategy, whereby females spawn many times over an extended reproductive season. Female round gobies were collected from the upper Detroit River (by trawling and angling) during spring, summer, and fall of 1996 in order to determine fecundity patterns and length of the reproductive season. Female round gobies were mature at 1 year of age, which is 1 year earlier than has been noted for gobies in Europe. Gravid females were present in May and declined at the end of July, which indicates that spawning occurs from spring until midsummer. Mean fecundity was 198 eggs, and variation in fecundity was correlated with standard length (r 2 ϭ 0.76, P Ͻ 0.0001) of females. Fecundity was lower than that observed for the same species in Europe, but it was generally higher than that of most native species with which gobies would compete. A field experiment showed that artificial nests contained fewer eggs but were used more often by more spawning females than were such nests in Europe. The relatively high fecundity (compared with that of native species), rapid maturation, aggressive behavior, and extended spawning season may favor the continued expansion of round gobies throughout the Great Lakes.
Knowledge and Management of Aquatic Ecosystems, 2016
Padogobius bonelli is a goby native to Northern Italy, but several populations are established in Central Italy out of its native range. P. bonelli caused negative impact on native fish community but any study on growth in the introduced areas has ever been conducted. In this study age, growth and condition of a non-native population of P. bonelli from the River Aggia were investigated. Samples (n = 422) were collected monthly from January to December 2012. Age estimation was based on scalimetry and five age classes (0 +-4 +) were observed. Sex ratio was strongly male-biased. Growth in previous years was determined by back-calculation from scale measurements and the occurrence of Lee's phenomenon was tested. Von Bertalanffy growth parameters were estimated (Males: L ∞ = 8.35 cm, k = 0.40, Φ = 1.44; Females: L ∞ = 8.71, k = 0.43 , Φ = 1.51). No differences in growth between sexes were observed, despite sexual dimorphism based on the larger size of males is count as a typical trait of the species. This result could be affected by the reverse Lee's phenomenon that acts only on females, since in the population selectively survived females of larger size. Smaller females would be disadvantaged, especially during the breeding season, as highlighted by the low somatic condition observed in the period April-June.
Aquatic Invasions, 2018
Padogobius nigricans and Padogobius bonelli are two gobies native to Italy and characterized by an allopatric distribution: P. nigricans is endemic to the Tyrrhenian catchment of central Italy, while P. bonelli is endemic to the Adriatic catchment of Northern Italy. In the past two decades P. bonelli has successfully established in central Italy outside of its original area of distribution, coming into contact with populations of P. nigricans. The superiority of P. bonelli in competition for breeding sites is well documented by laboratory studies; however, little evidence from the field has been provided. In this study, the occurrence and abundance of the two gobies were investigated in the River Tiber basin (central Italy) to assess the impacts of P. bonelli expansion on P. nigricans populations. Moreover, to investigate nest interference by P. bonelli towards P. nigricans, shelter occupancy of the two Italian gobies was investigated in the field with respect to individual density. Sampling was conducted by electrofishing in 77 sites throughout the upper River Tiber basin and nest occupation was analyzed in 8 river stretches. Padogobius bonelli has further expanded its distribution in recent years, following both natural and human-mediated dispersal patterns. It is numerically dominant over P. nigricans and fewer P. nigricans juveniles were found in the invaded than the uninvaded areas. Depending on adult density, P. bonelli can occupy up to 97% of nest sites and can seize a significant percentage of shelters even at low adult abundance. The expansion of P. bonelli into newly colonized areas in recent years has increased concern for the conservation of P. nigricans. In the invaded areas, the survival of P. nigricans populations is mostly through migration of individuals from the uninvaded areas located upstream of weirs, allowing isolated populations of this vulnerable and endangered species to persist.
Age, growth and reproduction of Cobitis paludica in a seasonal stream
Journal of Fish Biology, 2002
In the Iberian endemic loach Cobitis paludica, in a small seasonal tributary of the Guadalquivir River, 65–70% of the total growth in length occurred in the first year of life. The maximum ages observed were 3+ years in males and 4+ years in females. Both sexes matured at the beginning of their second year of life. There was a significant difference from 1: 1 in the overall sex ratio of 412 males to 674 females. Spawning began in late March and ended in July. Cobitis paludica is a multiple spawner that releases a minimum of two batches of eggs per female each year. Once spawning had started, however, there was no recruitment from the stock of transparent oocytes to the mature stock. The number of eggs decreased from the first batch to the second, but there was no significant difference in the mean egg diameter between batches. Compared with other populations of this species, the present population, from a low latitude, is characterized by a low number of age groups, fast growth, ear...
Annual Research & Review in Biology
The reproduction of Neochelon falcipinnis was studied in the Marine Protected Area (MPA) of Niamone-Kalounayes located in the Casamance estuary (Senegal) from July 2021 to June 2022. The results of this study are presented after twelve (12) months of experimental seine fishing. Reproductive parameters such as length-weight relationship, condition factor (K), sex ratio (SR), gonadosomatic index (GSI) and size at first maturity (Lm50) were determined. A total of 386 individuals (150 males, 221 females and 15 of undetermined sex) were sampled. The sex ratio was in favour of females (0.68 or 1:1.47). The length-weight relationship showed a minor allometric growth with allometric coefficient b values of 2.70 for both sexes combined, 2.60 for males and 2.79 for females. The ANOVA test showed no significant difference in condition factor in males (P > 0.05). In contrast, in females, there was a significant difference at the beginning of the cold season (P < 0.05). The monthly change...