In this study, we examined how chemical cues from a predatory marine crab affect the transmission of a parasitic trematode from its first (periwinkle) to its second (mussel) intermediate host. We collected the data in a laboratory experiment. Here, snails (Littorina littorea) infected with a parasite (Himasthla elongata) were kept in two different treatments (with predation risk and control). Subsequently, the excreted cercariae were collected as data. The experiments were conducted at the Wadden Sea Station of the Alfred Wegener Institute in List, Sylt, Germany. We sampled the snails at the the Danish coast of the Baltic Sea (Jütland, Arosund; 55*15'45.8'N 9*42'39.2'E). Snails had a shell height of 14-18mm corresponding to an age of two years. Infection status were screened at the laboratory. The crabs for the predation cue were sampled at the Oddewatt, List Sylt (German, Wadden Sea). Only male crabs with a size og 20-30mm catapace width were sampled. The blue mussels were sampled at the west coast of Sylt (Wenningstedt beach) were trematode infection do not occur naturally (confirmed by screening 50 mussels).
In this study, we examined how chemical cues from a predatory marine crab affect the transmission of a parasitic trematode from its first (periwinkle) to its second (mussel) intermediate host. We collected the data in a laboratory experiment. Here, snails (Littorina littorea) infected with a parasite (Himasthla elongata) were kept in two different treatments (with predation risk and control). Subsequently, the excreted cercariae were collected as data. The experiments were conducted at the Wadden Sea Station of the Alfred Wegener Institute in List, Sylt, Germany. We sampled the snails at the the Danish coast of the Baltic Sea (Jütland, Arosund; 55*15'45.8'N 9*42'39.2'E). Snails had a shell height of 14-18mm corresponding to an age of two years. Infection status were screened at the laboratory. The crabs for the predation cue were sampled at the Oddewatt, List Sylt (German, Wadden Sea). Only male crabs with a size og 20-30mm catapace width were sampled. The blue mussels were sampled at the west coast of Sylt (Wenningstedt beach) were trematode infection do not occur naturally (confirmed by screening 50 mussels). Mussel shell length wars 25-30mm.
In this study, we examined how chemical cues from a predatory marine crab affect the transmission of a parasitic trematode from its first (periwinkle) to its second (mussel) intermediate host. We collected the data in a laboratory experiment. Here, snails (Littorina littorea) infected with a parasite (Himasthla elongata) were kept in two different treatments (with predation risk and control). Subsequently, the excreted cercariae were collected as data. The experiments were conducted at the Wadden Sea Station of the Alfred Wegener Institute in List, Sylt, Germany. We sampled the snails at the the Danish coast of the Baltic Sea (Jütland, Arosund; 55*15'45.8'N 9*42'39.2'E). Snails had a shell height of 14-18mm corresponding to an age of two years. Infection status were screened at the laboratory. The crabs for the predation cue were sampled at the Oddewatt, List Sylt (German, Wadden Sea). Only male crabs with a size og 20-30mm catapace width were sampled. The blue mussels were sampled at the west coast of Sylt (Wenningstedt beach) were trematode infection do not occur naturally (confirmed by screening 50 mussels). Mussel shell length wars 25-30mm.
In this study, we examined how chemical cues from a predatory marine crab affect the transmission of a parasitic trematode from its first (periwinkle) to its second (mussel) intermediate host. We collected the data in a laboratory experiment. Here, snails (Littorina littorea) infected with a parasite (Himasthla elongata) were kept in two different treatments (with predation risk and control). Subsequently, the excreted cercariae were collected as data. The experiments were conducted at the Wadden Sea Station of the Alfred Wegener Institute in List, Sylt, Germany. We sampled the snails at the the Danish coast of the Baltic Sea (Jütland, Arosund; 55*15'45.8'N 9*42'39.2'E). Snails had a shell height of 14-18mm corresponding to an age of two years. Infection status were screened at the laboratory. The crabs for the predation cue were sampled at the Oddewatt, List Sylt (German, Wadden Sea). Only male crabs with a size og 20-30mm catapace width were sampled. The blue mussels were sampled at the west coast of Sylt (Wenningstedt beach) were trematode infection do not occur naturally (confirmed by screening 50 mussels). Mussel shell length wars 25-30mm. Sampling of the experimental organisms: Mytilus edulis (latitude:54.937.600, longitude: 8.312.915); Littorina littorea (latitude55.262.722:longitude:9.710.889 ) and Hemigrapsus takanoi (latitude:55.028.713longitude:8.434.260 ).
Objective: The ultimate goal is to produce a method which details the incidence of parasitic infestation according to location, frequency and time of the year. General Information: In order to determine whether parasitism changes the decrease in water pollution and how it affects the quality and quantity of the fish harvest, measurements will be taken from individuals of edible species in Lake Constance. The fish caught will be subjected to a quantitative and qualitative examination for ectoparasites and a histological study (especially concentrated on cestodes and cestodaria) for endoparasites. Other subjects to be studied are how parasitism can affect growth and how feeding can be responsible for infestation. Also, the possible seasonal variation in parasitic infestation will be reported. Achievements: Fish, including edible ones from 7 various locations around the upper lake of Lake Constance and the Alpenrhein, were investigated regularly for parasites. The statistical distribution of most of the commonest parasite species fitted closely to the negative binomial. Seasonal and location dependent differences relating to parasitic infestation were found with the digenean trematodes Bunodera lucipercae, Ichthyocotylurus variegatus and the cestodes Proteocephalus percae and Proteocephalus exiguus occurring seasonally. Perth and roach caught in front of Langenargen were less infested with Diplostomum spathaceum and Tylodelphys clavata than those taken from Bottighofen. Perth and roach populations from these locations do not interchange. The condition of white fish (infested with P exiguus) and of perch (invaded by D spathaceum, I variegatus, adult P percae, cysts of Trainophorus nodulosus and T clavata) was not influenced by parasites because of the great food resources. The condition of white fish caught in the Alpenrhein was worse than of those caught in the middle of the lake because the river is colder and the food is limited. Female white fish and perch were more invaded by Proteocephalus (intermediate hosts: copepods) than males during the spawning season because the food consumption of the females was higher. Cyprinids (bream, dace and roach) were less infested with Digenea (D spathaceum, T clavata) in comparison with results gained in the seventies. The decreasing eutrophication has caused a decrease of the intermediate hosts (snails). All the parasite species found are not infectious to man.