Examining diversity of ground dwelling terrestrial invertebrates on Sable Island

Abstract

Islands are often in remote locations, yet these areas can gain species and increase their overall diversity due to the dispersal of organisms. Sable Island is unique not only for its biodiversity but also because it is the only part of a sand bar not submerged by the North Atlantic Ocean. Knowledge surrounding invertebrates on Sable Island is limited, with the last known inventory occurring in 2016. I investigated invertebrate abundance and composition on Sable Island to determine the effects that two different vegetation communities (marram grass and heath) had on these species. Five sites with nine pitfall traps at each site were set up in each of the vegetation types located across Sable Island. Trapped invertebrates were collected every two days for a total of six days, although this thesis focuses only on the first collection. Invertebrates were first identified to family level, and then to species level when possible. Overall, invertebrates were significantly more abundant and species rich in heath vegetation than marram grass. Additional findings showed variability among the types of species identified at each vegetation, most often only occurring on one or the other. Out of the 38 invertebrates successfully identified to species level, four were reconfirmed after going undetected for over forty years and two were new records on Sable Island: the ant Myrmica americana Weber and the lady beetle Nephus ornatus ornatus Leconte. The information gained has provided a quantitative, up to date list of the invertebrate species currently inhabiting heath and marram grass vegetation on Sable Island. Overall, this study has provided more insight into the types of ground dwelling invertebrates that live on the island and I conclude that with the large difference between the two vegetation types that invertebrates are more abundant and diverse in heath than marram grass vegetation.