AN EVALUATION OF THE EFFECTS OF ANTHROPOGENIC ABIOTIC DISTURBANCE ON THE FORAGING BEHAVIOURS OF DYTISCUS SPP. LARVAE OF SASKATCHEWAN
Date
2024-04-30
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0009-0004-6314-499X
Type
Thesis
Degree Level
Masters
Abstract
With urbanization practices, humans are altering the nature of abiotic stimuli to which animals are exposed. Understanding how animals deal with these disturbances may be critical from a management perspective, to minimize effects while still allowing for industrial development. I investigated the hunting success of predatory larvae of Dytiscus spp. in relation to four abiotic stimuli that are affected by encroachment on aquatic ecosystems (wind, ground vibrations, turbidity, and temperature). Dytiscus spp. are dispersed globally and will experience encroachment in the future. They have charismatic hunting behaviours that may be prone to disturbance.
Survival trials were conducted using larval Dytiscus spp. as predators and adult Gammarus lacustris as prey. Organisms were exposed to either a high, low, or absent (control) level of disturbance from each of the four stressors in different experiments. Each survival trial featured a five-minute separated acclimation period after which the predator and prey were allowed another five minutes to interact. Both individuals were recorded and behavioural differences among treatment groups (no vs. low vs. high disturbance) were assessed with regards to general activity as well as other behaviours. Despite finding no significant difference in overall prey consumption because of manipulating abiotic disturbances, results suggest that Dytiscus larvae switch from an ambush strategy to opportunistic strategies in disturbed environments. Also, the intensity of the abiotic stimuli and the water temperature may additionally increase variance of these behaviours. Ambush behaviours tend to occur in calm clear 23 ̊C water while opportunistic foraging occurs in disturbed environments but will reduce in speed as turbidity increases. Additionally, it appears that novel abiotic stimuli may have a significant effect on predatory behaviours.
It remains a question as to how Dytiscus larvae decide to use ambush foraging behaviour and what levels of interference will change their behaviour. However, this project serves as the groundwork for future experiments investigating the role of abiotic impairment in aquatic insect predators. With an ever-expanding human population, and industrial development, we should seek solutions to mitigate potential changes to aquatic communities and the problems they pose to aquatic invertebrate predators.
Description
Keywords
dytiscus, anthropogenic, encroachment, interference, behaviour
Citation
Degree
Master of Science (M.Sc.)
Department
Biology
Program
Biology