Morphological variation, reproductive biology and genetic structure of an invasive marine crab, Carcinus maenas

Author: René Campbell

Campbell, René, 2021 Morphological variation, reproductive biology and genetic structure of an invasive marine crab, Carcinus maenas, Flinders University, College of Science and Engineering

Terms of Use: This electronic version is (or will be) made publicly available by Flinders University in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. You may use this material for uses permitted under the Copyright Act 1968. If you are the owner of any included third party copyright material and/or you believe that any material has been made available without permission of the copyright owner please contact with the details.


Marine bioinvasions are becoming more frequent due to an increase in maritime activities especially with shipping transport carrying over 80% of the world trade. The European shore crab, Carcinus maenas, is one of the most widespread marine invasive species worldwide and can cause ecological and economic impacts on intertidal communities and shellfisheries. European shore crabs possess biological traits that increase their invasion success, such as high reproductive output, physiological tolerance and plasticity to local environment conditions, and varying genetic diversity. These traits allow new crab incursions to rapidly establish or help crabs expand their range. Research into C. maenas population biology and invasion ecology was limited for its invasive range in the southern hemisphere, including in southern Australia. This PhD project investigated C. maenas population biology and traits that may drive invasion success for this species throughout coastal habitats of Gulf St Vincent, South Australia. This thesis specifically addressed morphological variation, reproductive biology and genetic structure of South Australian C. maenas. Chapter 2 presents morphological and mitochondrial COI gene analyses to confirm the species of Carcinus present in South Australia. The study revealed that the species in South Australia is the Atlantic C. maenas and highlighted that Carcinus are accurately identified with molecular analysis. Chapter 3 used morphometrics and the COI gene to assess intraspecific variation of C. maenas across different habitats in Gulf St Vincent. Morphometric variation was observed across habitats as a possible indicator of phenotypic plasticity, while genetic homogeneity suggested C. maenas in South Australia comprise a single genetic population. Chapter 4 examined the ovary development, size at sexual maturity, fecundity and the reproductive period of female C. maenas. Females have early onset of maturity, produced an average of 200,000 eggs per brood, and spawn up to nine months of the year during cooler seasons. Chapter 5 presents next-generation sequencing of SNP markers (DArT-Seq) and the COI gene to contrast genetic diversity, genetic structure and demographic histories of South Australian C. maenas to other populations across its global range. South Australian C. maenas had high genetic diversity and were genetically distinct, while demographic history revealed Europe and southeast Australia as the most likely source populations. This research project identified biological characteristics such as morphological plasticity, high reproductive potential and diverse genetic structure that influence invasion success of C. maenas in South Australia. Understanding biology of this global invader will assist with research and management of marine invasive species.

Keywords: invasive species, crustacea, marine bioinvasions, ecology, reproduction, histology, genetics, morphometrics, morphology, species identification, SNPs, mitochondrial DNA, phenotypic plasticity, South Australia

Subject: Biological Sciences thesis

Thesis type: Doctor of Philosophy
Completed: 2021
School: College of Science and Engineering
Supervisor: Sabine Dittmann