BEHAVIOURAL, ANATOMICAL AND PHYSIOLOGICAL EXAMINATIONS OF CRAB HOST-PARASITE INTERACTIONS

Abstract

The main objective of this thesis was to study crab host-parasite interactions though the examination of changes in behaviour, anatomy and physiological processes. Atlantic rock crabs (Cancer irroratus) infected with Nectonema agile and green crabs (Carcinus maenas) infected with Profilicollis botulus were subjected to predator evasion and aggression tests. Additionally, green crabs were tested for their righting response. Size (carapace width), body weight, testes weight and hepatopancreatic lumen areas were measured in rock crabs. Hepatopancreatic glycogen reserves were measured in green crabs. Parasitized rock crabs increased their speed in the aggression test and had significantly smaller testes than unparasitized counterparts. As P. botulus transitioned from acanthellae to cystacanths, they caused green crabs to increase time spent at the midline and decreased their speed, distance travelled and glycogen reserves. During the later cystacanth stage, these crabs righted themselves faster and had larger glycogen reserves than unparasitized crabs. These results provide important insight into host health and parasitic lifecycles.