Reproduction in a recently established population of green crab, Carcinus maenas, in Placentia Bay and juvenile targeted mitigation to prevent mussel aquaculture as a vector for introduction and spread

Best, Kiley Morgan (2015) Reproduction in a recently established population of green crab, Carcinus maenas, in Placentia Bay and juvenile targeted mitigation to prevent mussel aquaculture as a vector for introduction and spread. Masters thesis, Memorial University of Newfoundland.

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Abstract

Invasive species are organisms that are introduced to a new environment via natural or anthropogenic means and cause damage to the native biota through interactions with the native species and habitat. Aquatic invasive species (AIS) in marine coastal ecosystems can thrive in coastal areas in their native and non-native ranges as they have fewer natural barriers to contain spread versus terrestrial environments. AIS spread via vessel traffic, movement of industrial and recreational equipment and currents, weather events, and other organisms in their fluid environment. Generally, invasive species have the ability to tolerate extreme and restrictive conditions with means to make adjustments to their survival strategies to survive and establish populations in areas outside of their native ranges. In this study, we look at the reproductive strategies of the European green crab (Carcinus maenas) in recently invaded cold-tolerant populations in Newfoundland. We estimate size minimums for physiological maturity in males and females, timing for mating behaviors, duration of each stage of egg development and timing of larval release in females. This information has been used to establish minimum size thresholds for pilot mitigation efforts in the area and will continue to help pinpoint the best times of year to target a particular life stage for this region. Comparisons to other non-native green crab populations in Atlantic Canada are made to elucidate some of the strategic changes they have made in these environments. This information can be used in targeting different life stages in efforts to control already established populations in Newfoundland and prevent spread and establishment to new areas. This information is then used to pinpoint a vulnerable (likely to settle in and around mussel seed lines of the aquaculture industry) life stage of juvenile green crab to target via mitigation. This was investigated by exposing juveniles to a series of heated salt water immersion treatments. Experiments confirmed that exposing juvenile green crab to heated salt water for no longer than 1 minute at 45°C is sufficient to cull the crab while not causing any significant physiological stress to mussel seed. This information and subsequent control measures are valuable to the mussel aquaculture industry, stakeholders and managers for designing plans for future control of this invasive species.

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