Orientador: Reinaldo José da Silva / Resumo: Ergasilidae Burmeister, 1835 é uma das maiores e mais importantes famílias de copépodes parasitas. Atualmente, esta família conta com 29 gêneros válidos e mais de 260 espécies descritas. Esses pequenos copépodes são, em sua maioria, parasitas de peixes (ósseos e cartiloginosos), e podem ser encontrados parasitando as brânquias, narinas, superfície, nadadeiras, ou até mesmo, a bexiga natatória de seus hospedeiros. No Brasil, Ergasilidae representa a quarta maior família de copépodes de água doce e a maior família de copépodes parasitas, com cerca de 60 espécies e 18 gêneros. Apesar disso, diversos autores assumem que apenas uma pequena porção da “real” diversidade de ergasilídeos no Brasil é atualmente conhecida. Nesse contexto, o objetivo do presente estudo foi a identificação e a descrição dos ergasílideos parasitas de brânquias e narinas de peixes do reservatório de Jurumirim e seus tributários (rios Paranapanema, Taquari e Ribeirão dos Veados), Alto rio Paranapanema, localizados no Estado de São Paulo, Brasil. Um total de 460 espécimes de peixes das seguintes espécies, Astyanax fasciatus (Cuvier, 1819) (n = 125), Cyphocharax modestus (Fernández-Yépez, 1948) (n = 177), Pimelodus maculatus Lacepède, 1803 (n = 91), Prochilodus lineatus (Valenciennes, 1837) (n = 37) e Schizodon intermedius Garavello & Britski, 1990 (n = 30), foi analisado quanto a sua fauna de copépodes parasitas. Com base nas análises morfológicas foram identificadas 11 espécies pertencentes a 8 gêneros de Er... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

Ergasilus sieboldi has been reported from a number of trout fisheries in England and Wales. The population dynamics of this parasitic copepod in Rutland Water, a large reservoir in Central England was studied from 2003 to 2005. A combination of angler and net caught fish were examined to record numbers of adult females and egg production throughout each year. The parasite overwintered in large numbers on trout and commenced egg production in April which then continued until October/November. The prevalence of infection and the abundance of the parasite were very high in overwintered rainbow trout but these parameters then decreased in March as large numbers of uninfected fish were stocked into the reservoir. The parasite population then increased until October. Infection levels in 2004 and 2005 were significantly lower than in 2003. Infections of cage-held rainbow trout showed that E.sieboldi could become ovigerous within two weeks of attachment to trout in July and August. New infections occurred from June until November. Several species of coarse fish examined were also shown to be infected by the parasite. Cage trials showed that triploid rainbow trout were infected by significantly higher numbers of the parasite than diploid rainbow, brown trout or “blue” rainbow trout. Observations of infected fish in experimental tanks showed that overwintering parasites were stimulated to commence oviposition by increasing water temperatures. Photoperiod had no noticeable effect on the parasite. Egg viability and rate of development was studied using tank held infected fish and in vitro incubation techniques. Viability of eggs in sacs detached from the adult parasite was greater than those remaining attached. The rate of egg development was modelled and was shown to be predicted by temperature. Development of eggs was estimated to commence at 3.6ºC. Eggs developed more rapidly at higher temperatures and at peak production, inter-clutch interval was between 0 and 0.5 days. Egg production models estimated that an overwintered parasite could produce up to 19 clutches of eggs between April and October under normal temperature regimes measured at the reservoir. Ovarian development during the winter was confirmed using classifications of ovary size and shape based on parameters measured using image analysis techniques. The life span of E.sieboldi was estimated at 10-12 months. Nauplii culturing techniques were compared, and nauplii to stage V were successfully developed. Nauplii hatched from the eggs of adult parasites occurring in the spring were larger and conditioned to develop at lower temperatures than those hatched later in the year. Nauplii were fed on 4 different types of algae held in monocultures but development occurred only in algal polycultures. A comparison was made of nauplii feeding preferences and development with algae recorded in Rutland Water in 2003 and 2005 but no correlations were found. Fish stock assessment was carried out using models of angler catch, effort and stocking figures from the fishery. Parasite numbers on the overwintered fish were estimated at 12 million parasites in April 2003, 8.3 million in April 2004 and 1.2 million in April 2005. Stock assessments suggested a reduction in number of overwintering trout and effects of stocking policy to be at least partially responsible for the decline in the parasite population. The results of this study formed a management strategy for the operation of the trout fishery.