Parasite transfer from crustacean to fish hosts in the Lübeck Bight, SW Baltic Sea

Abstract

Four helminth parasites out of 19 species found in the Liibeck Bight, Baltic Sea, were chosen for investigations on the transfer from invertebrate to small-sized fish hosts: larvae of the tapeworms Schistocephalus sp. and Bothriocephalus sp. (Cestoda) living in planktonic copepods as primary hosts; Podocotyle atornon (Digenea) and Hysterothylacium sp. (Nematoda) were found in benthic crustaceans, especially Garnmarus spp. These hosts were the prey of 3 gobiid fishes, Gobiusculus flavescens (feeding mainly on plankton), Pornatosctn'stus minutus (preferring benthos), and P. pictus (feeding more on plankton than benthos). Because the fishes selected smaller sizes of crustaceans, they ingested all stages of the copepods but only the smaller-sized groups of gammarids which were often less infested by parasites. In order to evaluate the probability for a fish to be parasitized by a helminth, an infestation potential index (IP) was calculated. Podocotyle atomon and Hysterothylacium sp. revealed an IP which was far lower in gobies than expected when the prevalences of the previous hosts were taken into consideration. The IP of tapeworm larvae was mainly influenced by the feeding pressure of the gobiid predators, which might change with developmental stage and season. It is concluded that parasite transfer to the next host decreases when sizes of prey and predator differ only moderately. This mechanism can reduce the numbers of parasites transferred to less suitable or wrong hosts.

Parasite communities of the Schlei Fjord (Baltic coast of northern Germany)

“…Gulls and terns from OeheSchleimiinde, a nature reserve near the site of Olpenitz, harboured among other helminths adult Maritrema subdolum as well as Cryptocotyle concavum but not Microphallus claviformis (Kreft, 1991). The prevalence fluctuations of these three parasites and Podocotyle atomon in intermediate hosts were similar to those found at other sites (MacKenzie & Gibson, 1970;Zander et al, 1984Zander et al, , 1994. The cycle of the fish digenean Podocotyle atomon is interrupted in Missunde due apparently only to the absence of the first host Littorina saxatilis or L. fittorea.…”

“…This trend has already been recorded (Wendland, 1985;Kreft, 1991;Zander & Westphal, 1991;Gollasch & Zander, 1994). Contrarily, Pomatoschistus mmutus, Gammarus locusta and Hydrobia ulvae were the most important hosts in the Lfibeck Bight (W Baltic Sea with more than 10 %o salinity) (Zander et al, , 1994Strohbach pers. comm.).…”

Colonization and seasonality of goby (Gobiidae, Teleostei) parasites from the southwestern Baltic Sea

“…This is also a general trend in intermediate hosts such as snails and crustaceans, which are infested in autumn and serve as a reservoir for the infestation of ®sh hosts in the spring (Uspenskaja 1963;MacKenzie and Gibson 1970;Lauckner 1994;Gollasch and Zander 1995;Kesting et al 1996). As early as autumn, young gobies may also bear latent stages of parasites such as metacercariae, acanthors, or plerocercoids, which still exist when the ®sh return in the spring from their deeper winter habitats (Koter 1962;Reimer 1970;Zander et al 1993Zander et al , 1994.…”

Population dynamics and parasitation of planktonic and epibenthic crustaceans in the Baltic Schlei fjord

“…Remarkable are the relatively high intensities of Podocotyle atomon in Crangon crangon which may emphasize a correlation of host size and numbers of parasite cysts in a single host. Size differences of cercariae also influence the intensities, because the large cercariae of Podocotyle atomon can only penetrate larger stages of crustaceans (Wendland, 1985;Zander & D6ring, 1989;Zander et al, 1994) and not small hosts, as can Maritrema subdolum.…”