Data from: From spawn to survival: Decoding the hydraulic conditions for successful silver carp egg incubation
Abstract
Natural rivers exhibit complex and dynamic flow conditions that significantly impact the survival and development of semi-buoyant fish eggs. This study investigated the effects of flow velocities and turbulence on the semi-buoyant fish eggs in running water, using silver carp eggs as a representative species. Experiments conducted in a race-track flume revealed that moderate flow conditions (0.5 m/s) yielded the highest hatching rates, while excessive velocities (1.1 m/s) led to complete mortality at the blastula stage. Mild turbulence benefited egg incubation, but extreme turbulence reduced hatching rates and increased larval deformation. These findings demonstrate a clear relationship between hydraulic conditions and successful egg development, suggesting that optimal spawning and hatching conditions are differ. The results provide a foundation for evaluating suitable hydraulic conditions for semi-buoyant fish egg hatching in river habitats and offer insights into the potential impacts of hydraulic structures on fish populations. This research contributes to river ecosystem management, conservation of semi-buoyant fish species, and the design of fish-friendly hydraulic structures.
Dataset Description
This dataset contains experimental data examining the effects of flow velocities and turbulence on the development and survival of silver carp (Hypophthalmichthys molitrix) eggs. The experiments were conducted in an annular flume to investigate how different hydraulic conditions impact egg incubation, hatching rates, and larval development.
Experimental Methods
- Experiments conducted in a custom-designed annular flume
- Flow velocities ranging from 0.3 to 1.1 m/s
- Turbulence intensities varied at constant flow velocity (0.7 m/s)
- Water temperature maintained at 28±0.5°C
- Continuous monitoring of dissolved oxygen (minimum 7 mg/L)
Data Files and Structure
The dataset (data.xlsx) contains 8 worksheets:
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Fig 2: Measurement results of flow characteristics in the annual incubation channel
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Fig 3: Flow turbulence intensity calculation results
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Fig 4: Impacts of mean flow velocities on the hatching rates of silver carp
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Fig 5(a): Dead eggs observed at different developmental stagea within different flow velocities
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Fig 5(b): Dead eggs observed at different developmental stagea within different turbulence intensities, operting at the same mean flow velocity of 0.7 m/s.
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FigS2: Measurement results of turbulent intensity
Note: (1) Contents highlighted in yellow were used to improve readability.
(2) Text in red font indicates flow values - the fundamental parameters for working condition control.
Data Collection Methods
- Egg development monitored using high-resolution portable microscope (SHOCREX DM9, 1000X)
- Flow velocities measured using Acoustic Doppler Velocimeter (ADV, Vector 300m)
- 72 measurement points distributed across 8 cross-sections
- Sampling frequency: 25 Hz with 100s sampling time per point
Variables and Units
Flow Parameters:
- Mean flow velocity: meters per second (m/s)
- Water depth: meters (m)
- Hydraulic radius: meters (m)
- Kinematic viscosity: square meters per second (m²/s)
- Reynolds number: dimensionless
- Froude number: dimensionless
Biological Parameters:
- Hatching rate: percentage (%)
- Deformity rate: percentage (%)
- Development stages: according to Amy E. George's method
Usage Notes
- Data quality for ADV measurements ensured by correlation coefficients >80% and SNR >15db
- Development stages defined when >50% of fertilized eggs reached specific stage
- Total incubation duration: 21-23 hours post-fertilization
Acknowledgments
This study was supported by National Natural Science Foundation of China (No. 42007213)
Citation
When using this dataset, please cite: https://doi.org/10.5061/dryad.4tmpg4fm4
Contact Information
For questions about the dataset, please contact:
- Xian-bing Zhang
- Email: zhangxb@cqjtu.edu.cn
- Chongqing Jiaotong University, Chongqing, China
Collection of silver carp eggs
The Animal Care and Use Committee of Chongqing Jiaotong University granted us permission to possess silver carp (Hypophthalmichthys molitrix) eggs and larvae in a laboratory setting for research purposes only (Permit No. Wang-20220325-002). The silver carp eggs were obtained from Yongchuan Shuihua Fishery Association, a fishery farm located in Chongqing, (105.9°E, 29.263°N), from May to July in 2022 and 2023.
Design of Race-track flume
A Race-track Flume (RTF) was designed for this study to investigate silver carp egg development under controlled flow conditions. The FTR, depicted in Figure. 1, consists of three main components aligned at the top: an incubation channel, a buffer channel, and an overflowing weir.
The incubation channel, serving as the primary experimental area, measures 0.20 m in width and 0.40 m in height, with an operational water depth of 0.30 m. Adjacent to this, the buffer channel has the same width but reduced height of 0.20 m. This design ensures stable flow transition between channels.
Flow control was achieved through two inlet pipes, each followed by two inflows. The angles between these inflows and the flume wall were adjusted to either 45° or 135°, allowing precise regulation of flow conditions in the incubation channel by modifying inlet pipe flow rates (Figure S1).
To prevent fish egg loss, the system incorporates an overflowing weir (0.35 m in width and 0.10 m in height) equipped with a finely woven mesh featuring a 1 mm square grid. This design effectively contains the eggs while permitting water flow.
Characterization of flow conditions
1) Measurement of flow velocity
A comprehensive three-dimensional flow velocity measurement was conducted in RFT using an acoustic Doppler velocimeter (ADV, Vector 300m, Nortek Engineering AS Vector. Norway; detailed specifications available in Text S1). The measurement setup comprised 72 strategically designed points distributed across the flume. As illustrated in Figure.1 (c), these points were organized into 8 cross-sections along the flume length. On each cross-section, 3 vertical perpendiculars were set with an interval of 0.05 m. For every vertical perpendicular, measurements were taken at three relative heights: 0.2, 0.6, and 0.8 times the water depth. This systematic arrangement ensured a thorough capture of the flow dynamics throughout the RTF, providing a comprehensive dataset for analysis.
2) 2-D cloud map of flow velocity and turbulent intensity
To enhance the visualization and understanding of the flow field within the incubation channel, we employed Surfer V.15.0 software to generate 2-D cloud maps depicting flow velocity and turbulent intensity. The spatial interpolation of our data was accomplished using Shepard's method, a sophisticated three-dimensional interpolation technique integrated into the Surfer software package. This approach involved a two-step process: first, we plotted the in-situ average flow velocities derived from equation (2), and then estimated velocities in unmeasured areas through above interpolation method. For the 2-D cloud map illustrating turbulent intensity, we exclusively utilized data from equation (3), which specifically represented turbulence intensity in the x-direction. This focus on the x-direction was justified by the observation that turbulence intensity differences in the y-direction and z-direction were not statistically significant.
Selection of experimental parameters
High-speed turbulent streams are commonly found in mountain rivers such as the upper reaches of the Yangtze River (Alvarez et al., 2017; Beechie et al., 2006; Constantinescu et al., 2011; Li et al., 2023). These flows are crucial for the spawning of certain fish species, including the four major Chinese carps, which require a flow velocity of approximately 1.1 m/s to release their eggs (Chen et al., 2021). Additionally, a specific flow velocity is needed to keep semi-buoyant fish eggs suspended and alive (Prada et al., 2021). Therefore, flow velocities ranging from 0.3–1.1 m/s were utilized in the current study.
This comprehensive study investigated the effects of both flow velocity and turbulent intensity on silver carp egg incubation through two interconnected experimental series. This first series comprised six experiments examining flow velocity impacts. Five primary experiments (L1-L5, Table 1) utilized distinct average flow velocities (0.3, 0.5, 0.7, 0.9, and 1.1 m/s) in the incubation channel, while a control experiment (L0) employed a separate zero-velocity incubator with aerator-induced agitation for oxygenation. All experiments maintained a 0.3 m average water depth, with temperature continuously monitored in the buffer channel using a thermometer (model 1621A, manufactured by Hefei Zhice Electronic Co., Ltd., Hefei, China).
The second experimental series focused on turbulent intensity effects, consisting of four primary experiments (W1–W4, Table 2) and a control (W0). The primary experiments maintained a consistent 0.7 m/s mean flow velocity while varying turbulent intensities (0.0968, 0.1044, 0.1297, and 0.1439 m/s) in x-direction. As before, a separate zero-velocity incubator serves as the control (W0).
Experimental procedure
All experiments were conducted at the fishery farm. Prior to each experiment, flow conditions in the incubation channel were carefully adjusted to achieve the desired flow velocity and turbulence intensity, ensuring a stable environment. For every experimental run, 60 fertilized silver carp eggs at the 1-cell stage were carefully selected and transferred from the fishpond to the prepared channel. To ensure statistical robustness and reproducibility, each experiment was replicated three times, resulting in comprehensive study involving 1080 fertilized silver carp eggs. Throughout the incubation period, water quality was rigorously monitored to maintain dissolved oxygen level at a minimum of 7 mg/L, thereby providing optimal conditions for egg development.
Throughout the experiment, meticulous observation of silver carp eggs development was conducted at regular intervals. During the initial stages, eggs were examined every 30 to 60 minutes using a high-resolution portable microscope (SHOCREX DM9, 1000X magnification, Shenzhen Shu'an Technology Development Co., Ltd., Shenzhen, China). Once the organ differentiation stage was reached, observation intervals were extended to every 2 to 3 hours until hatching. The morphology and health status of silver carp eggs and larvae exposed to high-speed stream and turbulence were observed.
Particular attention was paid to the morphology and health status of eggs and larvae exposed to high-speed streams and intense turbulence. Water temperature was strictly controlled at 28±0.5°C and continuously monitored throughout the experiment. The onset of each developmental stage was defined as the point when over 50% of the fertilized eggs reached that specific stage. The total incubation duration, which varied between 21 and 23 hours depending on specific conditions, was recorded along with egg mortality rates at each stage.
Calculation of hatching rate and deformity rate
The hatching rate (%) of silver carp eggs and the deformity rate (%) of hatched larvae was calculated using the following equations.
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Z1=Y1/Y×100% |
(1) |
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Z1=Y2/Y×100% |
(2) |
Here, Z1 is the hatching rate, Z2 is the deformity rate, Y1 is the hatched larvae, Y2 is the deformed fish larvae, and Y represents the initial number of silver carp eggs.