Sam I'Ons: Determining the factors that drive invasion success of marine invaders
Wandering off to the far reaches of Tasmania and New Zealand to study Porcelain Crabs, Petrolisthes elongatus, may not appeal to everyone but for C3 Honours student Sam I’Ons it is a novel fieldwork approach for his 2011 Environmental Biology Honours project. By exploring the factors that drive the invasion success of non-native marine species in Australian waters he also hopes to gain a better understanding of predation mechanisms.
“These crabs are originally from New Zealand and were actually first recorded in Tasmania in 1876. Now they are abundant throughout Tasmania but we have no idea why they have become so successful,” I’Ons said.
Porcelain Crab, Petrolisthes elongatus Photo: Sam I'ons
Sam’s project also uses traditional comparative techniques, measuring life-history and demographic rates of invasive species in both their native and invasive ranges.
“I’ll be looking at the distribution and abundance as well as morphological attributes like length, biomass, carapace thickness and sex ratios, of the crabs, in both Tasmania and New Zealand to see if there are any differences. We already know that in Tasmania Porcelain Crab abundance can be around a 1000/sqm whereas in their native NZ environment it is only half this so this immediately raises questions about the processes underlying invasion success in introduced ranges,“ he said.
Sam’s supervisor, Dr Paul Gribben from the Biodiversity Research Group within C3, explains that this type of “invasive biogeographic” study is not often done in marine systems.
“Worldwide the economic and environmental impact of terrestrial invasive species has been enormous and the same thing is happening beneath the water. Unfortunately it’s a lot harder to see but the intertidal area that Sam is looking at is ideal and there is the added benefit of collaborating with colleagues from the University of Tasmania and Victoria University in Wellington, New Zealand. This research also compliments collaborative global research being undertaken in Chile so an Honours project such as this is very meaningful,” Dr Gribben said.
Sam is co-supervised by Dr Brad Murray, who leads the Biodiversity Research Group and is the Director of the Honours Management Committee for The School of the Environment.
C3 Honours students Sam I’Ons and Matthew West
with supervisor Dr Paul Gribben, far right
Matthew West:The spread of the invasive algae Caulerpa taxifolia
Dr Grbben’s ten year focus on invasive ecology also underpins Matthew West’s research into the invasive algae Caulerpa taxifolia highlighting the importance of the research history behind an individual Honours project.
“This highly invasive marine algae has been very successful in Australia and was probably introduced via the aquarium trade. Since its discovery in 2000 it has spread to 14 lakes and estuaries,” West said.
Often referred to as a “killer alga” because of its general robustness – although a tropical species it can tolerate temperatures less than 10°C and appears to favour already degraded environments – Caulerpa’s asexual reproductive mechanism means it can be spread from small pieces of fronds. Previous research undertaken by Dr Gribben also indicates that this alga acts as an ecosystem engineer; impacting sediments by producing toxic sulphides and removing oxygen completely, altering the sediments and, eventually, the biodiversity within that habitat. West, who is co supervised by Dr Justin Seymour, will investigate the physical, chemical and bacterial properties associated with Caulerpa invasions around Pittwater in Sydney.
“I hope my project can give some insight into the conditions that allow Caluerpa taxifolia to establish and grow, and what the mechanisms are, so that ultimately we might be able to develop a predictive framework for ‘at risk’ sites that haven’t been invaded by this algae yet,” West said.
Matt’s research is supported by New South Wales Department of Primary Industries, who are eager to understand the conditions that promote the success of Caulerpa.
The results of these projects will be presented at final honours seminars in November.
Honours applications for 2012 are now open: