Research Article |
Corresponding author: Samnao Saowakoon ( samnao.sa@rmuti.ac.th ) Academic editor: Christoph Chucholl
© 2023 Tuantong Jutagate, Wachira Kwangkhwang, Samnao Saowakoon.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Jutagate T, Kwangkhwang W, Saowakoon S (2023) Growth and competitions of the Australian red-claw crayfish, Cherax quadricarinatus (von Martens, 1868) in Thailand: the experimental approaches. Aquatic Invasions 18(1): 103-117. https://doi.org/10.3391/ai.2023.18.1.103301
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The Australian red-claw crayfish (RCC) Cherax quadricarinatus (von Martens 1868) (Crustacea: Decapoda: Parastacidae) has been introduced and promoted for freshwater aquaculture in many countries including Thailand. This study i) evaluates the growth performance of RCC in near-natural conditions relative to captive conditions and ii) investigates how successfully RCC can compete with a trophically and functionally analogous native species. Growth of RCC was compared among two aquaculture systems (concrete tank and earthen pond) and a treatment with simulated natural conditions. After 12 months of rearing, total length and weight were greatest in the earthen pond and poorest in the near-natural treatment, with significant differences in total length between the near-natural treatment and the two culture systems. Length-weight relationships showed that the RCC had positive allometry in the culture systems but negative allometry in the near-natural treatment. Competition was evaluated by means of a biotic resistance test and an additive–substitutive experiment between RCC and the native freshwater crab Esanthelphusa dugasti (Rathbun, 1902) (Crustacea: Decapoda: Gecarcinucidae). Specific growth rates after 90 days of the experiments suggest that the crab inhibited growth of RCC. This implies that the invasion of RCC in Thai waters could be limited by competition from resident freshwater crabs.
Parastacidae, length-weight relationship, biotic resistance test, additive–substitutive experiment, freshwater crab, specific growth rate
The revenue from fisheries and aquaculture in Thailand accounts for 10% of all agricultural sectors and 1% of the country’s GDP (
Other non-indigenous crayfish species, e.g., Procambarus clarkii (Girard 1852) and Cherax destructor (Clarke 1936), have previously been introduced to Thailand for ornamental purposes, but their presence in the natural environment has never been reported. However, RCC has been found extensively in some rivers and reservoirs in recent years, although the reports haven’t yet suggested any established populations (
The potential of an introduced species to become invasive depends on how well it grows and survives in the new environment. If environmental conditions are suitable, biotic resistance may still provide a means to inhibit establishment or spread of the introduced species. Biotic resistance can be either from the biodiversity of the ecosystem (i.e., the higher the biodiversity, the more the resistance against non-native species), or from predators or strong competitors of the introduced species (
All experiments were conducted at the fish farm of Ubon Ratchathani University, Ubon Ratchathani Province, Thailand. Ubon Ratchathani has a tropical wet and dry climate and consists of 3 seasons, namely summer (from March to June), rainy season (from July to October) and winter (from November to February). The annual mean maximum and minimum temperatures are around 35 °C and 20 °C, respectively (
Newly hatched RCC with average size and weight of 0.9 ± 0.2 cm in total length (TL) and 0.02 ± 0.02 g were acquired from a hatchery for the study. The animals were grown out in three treatments: concrete tanks, earthen ponds and community pond (natural conditions). The concrete tanks and earthen ponds were 2 × 2 m and represented two aquaculture conditions; both styles had three replicates. Water level was maintained at 60 cm, and 25% of the volume was exchanged every two weeks with tap water, which was vigorously aerated overnight. Pipe stacks were provided as shelter throughout the rearing areas. Three pen enclosures (2 × 2 m) constructed of bamboo poles and fine mesh net, without top or bottom, were set in a community pond to simulate natural conditions (Suppl. material
Two experiments were used to evaluate potential competition between RCC and a resident native species: (a) a test of biotic resistance (
Experiments were conducted in 2 × 2 m concrete tanks with water level maintained at 60 cm, with six replicates for each treatment. Three replicates were assigned for data collection, whereas animals in the remaining three tanks were kept to replace any dead individuals in the data collection tanks. Sex ratio of RCC in each treatment was 3 females: 2 males. In both experiments, the initial mean length and weight of RCC were 2.49 ± 0.10 cm and 0.32 ± 0.04 g, respectively. Initial mean carapace width and weight of crabs were 3.09 ± 0.14 cm and 2.05 ± 0.05 g.
For the biotic resistance test, growth performance of RCC was compared against native residents (i.e., freshwater crab). The first phase of the experiment lasted 30 days, and included five treatments (Table
Treatment | Resident animals at start (Day 1) | Introduced animals (Day 31) |
---|---|---|
Control | No animals | 5 red-claw crayfish |
Treatment 1 | 5 freshwater crabs (medium density) | 5 red-claw crayfish |
Treatment 2 | 10 freshwater crabs (high density) | 5 red-claw crayfish |
Treatment 3 | 5 red-claw crayfish (medium density) | 5 red-claw crayfish |
Treatment 4 | 10 red-claw crayfish (high density) | 5 red-claw crayfish |
Treatments for the additive–substitutive experiment with freshwater crab.
Treatment | Resident animals at start (Day 1) | Introduced animals (Day 31) |
---|---|---|
Control | 5 freshwater crabs | No animal |
Treatment 1 | 5 freshwater crabs | 3 red-claw crayfish (Additive, low density) |
Treatment 2 | 5 freshwater crabs | 10 red-claw crayfish (Additive, high density) |
Treatment 3 | 5 freshwater crabs | 3 freshwater crabs (Substitutive, low density) |
Treatment 4 | 5 freshwater crabs | 10 freshwater crabs (Substitutive, high density) |
For the growth performance study, the length-weight relationship (LWR) of RCC in each grow-out system was expressed by the exponential equation W = aLb, where W is the body weight (g); L is the total length (cm); a and b are the regression coefficients. Coefficient b can be used to indicate growth (
For the two competition trials, specific growth rates (%SGR) were calculated at two time intervals (day 1–30, day 31–90) for the introduced RCC (biotic resistance test) and resident crabs (additive–substitutive experiment), using the formula
where W is the body weight (g) and d is days. A significant difference in average %SGR among treatments in each experiment was tested by ANOVA. The assumptions for ANOVA test, i.e. normality and homoscedasticity, were met (P > 0.05). Differences were considered significant at α = 0.05. Dunn’s post hoc tests were performed in cases where the ANOVA found a significant difference. The orthogonal contrast procedure was applied to four comparisons in each experiment: (i) control vs other treatments; (ii) interspecific treatments vs intraspecific treatments; (iii) between different densities of the same species and; (iv) between different densities of different species. All statistical analyses were performed using R (
At the end of the growth experiment, mean length and weight of RCC (Figure
There was no significant difference in the initial weight of RCC reared as invaders at 30 days (before introduction) in each treatment (F4,10 = 1.355, P = 0.316). There was also no statistical difference in %SGR of these RCC among treatments (F4,10 = 0.896, P = 0.501; Figure
Orthogonal comparison of %SGRs of introduced Australian red-claw crayfish in biotic resistance test.
Comparison | F1,10-value | P-value |
---|---|---|
Control vs other treatments | 96.92 | < 0.001 |
Interspecific vs Intraspecific competition | 48.13 | < 0.001 |
Interspecific competition: low vs high density | 52.56 | < 0.001 |
Intraspecific competition: low vs high density | 1.40 | 0.264 |
Specific growth rates of Australian red-claw crayfish raised in the biotic resistance test after (A) 30 days and (B) 90 days. Different letters in each graph indicate significant differences (Dunn’s post hoc test, P < 0.05). L1 = interspecific competition at low density, H1 = interspecific competition at high density, L2 = intraspecific competition at low density, and H2 = intraspecific competition at high density.
For the additive–substitutive experiment, there was no statistical difference among treatments, either in terms of weight of crabs at start (average weight of 2.05 ± 0.05 g [F4,10 = 1.223, P = 0.361]) or %SGR after 30 days of initial rearing (average %SGR of 2.91 ± 0.14% [F4,10 = 2.433, P = 0.116; Figure
Orthogonal comparison of %SGRs of freshwater crab in additive–substitutive experiment.
Comparison | F1,10-value | P-value |
---|---|---|
Control vs other treatments | 58.33 | < 0.001 |
Interspecific vs Intraspecific competition | 47.86 | < 0.001 |
Interspecific competition: low vs high density | 10.01 | 0.01 |
Intraspecific competition: low vs high density | 5.41 | 0.042 |
Specific growth rate of freshwater crab in the additive–substitutive experiment after (A) 30 days and (B) 90 days. Different letters in each graph indicate significant differences (Dunn’s post hoc test, P < 0.05). L1 = interspecific competition at low density, H1 = interspecific competition at high density, L2 = intraspecific competition at low density, and H2 = intraspecific competition at high density.
Certain crayfish species including RCC are ranked among the top invasive aquatic animals globally, and are capable of negative impacts to native residents, habitats and ecosystems due to their plasticity in feeding and other behaviours. Although RCC has become popular as a farmed freshwater crustacean in many countries,
Female and male RCC have similar relative growth, and differences between the sexes are more in body shape than size (
The regression coefficient “b” from the LWR for RCC in the natural treatment indicates negative allometry (b < 3), unlike the culture systems, which both show positive allometry (
Successful invasion of non-indigenous crayfish into a new territory is common because they are often more aggressive and grow faster than the native residents (
Higher resource holding potential of native crabs than crayfish might help to control the invasion of RCC in Thai inland waters. However,
Invasive potential of the RCC is of concern worldwide, as it is now the second-most economically important crayfish after P. clarkii, and has been widely translocated (
Research conceptualization: T. Jutagtae and S. Saowakoon; sample design and methodology: T. Jutagtae; investigation and data collection: T. Jutagtae and W. Kwangkhang; data analysis and interpretation: T. Jutagtae and S. Saowakoon; draft manuscript preparation: T. Jutagtae. All authors reviewed the results and approved the final version of the manuscript.
The study was followed the Ethics statements Animal care and all experimental procedures (Animal use license number: U1-03817-2559).
The study was financially supported by the Biodiversity-Based Economy Development Office (Public Organization) Project: The potential on invasion of red-claw crayfish Cherax quadricarinatus (von Martens) in Thai inland waters. We thank the anonymous reviewers for their insightful comments and suggestions.
Photographs from growth performance experiment
Data type: figure (docx. file)
Explanation note: Photographs from growth performance experiment (A) experiment in the community pond (natural conditions), (B) preparing for measurement, (C) total length measurement and (D) weight measurement.