Abstract:
In recent years, due to the construction of large-scale water conservancy projects, human overfishing, lake reclamation, and water pollution had a serious impact on the reproductive migration and habitat of the Chinese mitten crab at the Yangtze River estuary. As a component of the living environment of aquatic organisms, substrate is of great significance for finding habitats for aquatic organisms and protecting aquatic organism resources. In order to explore the preferences of
Eriocheir sinensis at different developmental stages for the types of substrates, a single factor experiment method was used to study the effects of
E. sinensis on mud, silt (mud: sand=1﹕1), medium sand (0.35—0.50 mm) and fine sand (0.25—0.35 mm) at different developmental stages. The results of the study on parent crabs showed that in individual experiment, the percentages of time that parent crab stayed on the mud, silt, medium sand and fine sand were (58.18±6.34)%, (15.95±5.23)%, (12.05±2.38)% and (13.81±2.14)%; in the group experiment, the percentages of parent crabs appearing on the mud, silt, medium sand and fine sand were (33.69±2.17)%, (23.83±1.21)%, (20.15±0.34)% and (22.33±3.23)%, the individual and group experiment results of parent crabs showed that the parent crab preference for mud substrate was significantly higher than the other three substrates, and the differences between them were significant (
P<0.05). The results of the study on button sized crabs showed that in individual experiments, the percentages of time that button sized crabs stay on the mud, silt, medium sand and fine sand were (35.69±1.73)%, (18.08±3.25)%, (30.83±4.99)% and (15.40±1.91)%; in the group experiment, the percentages of times that crabs appeared on the mud, silt, medium sand and fine sand were (32.51±2.50)%, (19.80±3.84)%, (30.76±2.01)% and (16.93±0.95)%, the individual and group experiment results of the crabs showed that the button sized crabs have a preference for mud and medium sand substrate were significantly higher than the other two, and they were different from each other significant (
P<0.05). The percentages of times that juvenile crabs appear on the mud, silt, medium sand and fine sand were (60.42±2.89)%, (22.50±2.32)%, (8.75±2.50)%, and (8.33±1.10)%. Juvenile crabs like mud substrate the most, followed by silt, the differences were significant (
P<0.05). Studies on habitat methods showed that parent crabs have no obvious burial behavior, button sized crabs prefer to bury in mud and medium sand, while juvenile crabs prefer to bury in mud, followed by silt.
E.
sinensis have differences in the choice of substrate, and the requirements and habitat of
E.
sinensis at different developmental stages are also different. The results of this study provide a reference for habitat restoration and resource conservation of
E. sinensis.