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The present investigation evaluated the influence of seasonality and locality on the structure of the parasite community of the catfish Pimelodus blochii. A total of 160 fish were collected from two rivers in the State of Acre, western Brazilian Amazon: 80 fish in River Acre and 80 in River Iaco, with 40 in each season (rainy and drought). The overall prevalence was 78.7% and 1461 parasite specimens (adults and larvae) were allocated in 22 taxa: 5 of Monogenea, 10 of Nematoda, 3 of Digenea, 1 of Cestoda and 3 of Crustacea. In drought season, Procamallanus (Spirocamallanus) pimelodus and Demidospermus peruvianus were more prevalent in River Acre and Iaco, respectively. The parasite diversity (Brillouin index) as well as the prevalence and abundance of the monogeneans D. peruvianus, D. striatus, Demidospermus sp. and Ameloblastella sp. were higher in River Acre. The parasite community structure were dissimilar among rivers, and seasonally in River Iaco. These results suggest that environmental traits may overshadow seasonal influences on the parasite community structure, which may be related to the higher anthropization in River Acre. Furthermore, seasonality exerted less influence on the parasite community than expected, probably because the two rivers have different hydrological traits than those of other rivers in the Brazilian Amazon. New host and locality records expanded our knowledge of parasite biodiversity of P. blochii. Made available in DSpace on 2018-11-25T23:36:50Z (GMT). No. of bitstreams: 1 CPAFAP2018Communitystructureofmetazoanparasite.pdf: 1020163 bytes, checksum: 71f7901192d4cf1303b45eb0f06800e7 (MD5) Previous issue date: 2018-11-23

Studies on parasites of wild fish populations are important for knowledge of biodiversity, since parasites represent a great fraction of the planet?s biodiversity. The present study investigated the helminths fauna of Leporinus friderici, Mylossoma duriventre, Hoplerythrinus unitaeniatus and Osteoglossum bicirrhosum collected from the lower Jari River, in the state of Amapá in the eastern Amazon region, Brazil. These fish, which have varying eating habits, were caught using gill nets with different mesh sizes for analysis of helminths, using standard methodologies. The helminths collected from these hosts were: Procamallanus (Spirocamallnus) inopinatus, Guyanema seriei seriei, Contracaecum sp., Eustrongylides sp. (Nematoda), Clinostomum marginatum, Dadaytrema oxycephala, Caballerotrema aruanense, Posthodiplostomum sp. (Digenea), Quadrigyrus nickoli and Neoechinorhynchus sp. (Acanthocephala). Hoplerythrinus unitaeniatus presented the highest prevalence, intensity and mean abundance of C. marginatum, while M. duriventre was the host with lowest level of this parasite. The greatest diversity was of Contracaecum sp., sole helminth found in all species of fish studied. The presence of larvae of endoparasites indicates that these fish are intermediate hosts in the Jari River basin. Made available in DSpace on 2019-02-12T23:49:39Z (GMT). No. of bitstreams: 1 CPAFAP2019Helminthicendofaunaoffourspecies.pdf: 909329 bytes, checksum: 9e4a7a1de70a0b0e4fb798a8795ce2b2 (MD5) Previous issue date: 2019-02-12 e.393

This study has investigated the influence of unilateral eyestalk ablation on the survival, molting frequency, fecundity, reproductive output, and fertility of M. amazonicum females. We divided 96 females into with ablation and without ablation groups with six replicates. Water quality, growth, survival rate, intermolt period, molts number, and ovigerous females over a 90-day period were monitored. Unilateral eyestalk ablation reduced intermolt period by 30% and increased molts number, ovigerous females, and reproductive output. Our findings indicate that unilateral eyestalk ablation positively influences reproduction in M. amazonicum and is appropriate for females of this species having a body length of greater than or equal to 70 mm. Made available in DSpace on 2019-02-12T23:48:30Z (GMT). No. of bitstreams: 1 CPAFAP2019Unilateraleyestalkablationimproves.pdf: 2207733 bytes, checksum: 83d955bbd8779994deb13b0eaf25c605 (MD5) Previous issue date: 2019-02-12