Geology topics

Andres F. Prada

Publications and source records attributed to Andres F. Prada.

4 recordsLinked to original sources

USGS2021

Using turbulence to identify preferential areas for grass carp (Ctenopharyngodon idella) larvae in streams: A laboratory study

In this experimental series, we studied the swimming capabilities and response of grass carp ( Ctenopharyngodon idella ) larvae to flow turbulence in a laboratory flume. We compared three different experimental configurations, representing in‐stream obstructions commonly found in natural streams (e.g., a gravel bump, a single vertical cylinder, and patches of submerged rigid vegetation). Grass carp larvae (postgas bladder emergence) were introduced to each experimental configuration and subjected to a variety of hydrodynamic forces of different magnitudes and scales. We varied the flow velocities and water depths and found ranges of turbulent kinetic energy and Reynolds stresses that triggered a response in larval trajectories, identified by measured horizontal and vertical swimming speeds for each flow condition. Larvae apparently actively avoided areas with increased levels of turbulence by swimming away, moving faster in short bursts, and expending more energy. In addition to the magnitude of turbulent kinetic energy, the length scale and time scale of turbulent eddies also influenced the larvae response. These findings support the development of new strategies for controlling the spread of grass carp larvae in rivers, as well as the development of numerical tools incorporating active swimming capabilities to predict larval transport in streams.

Water Resources Research↗

USGS2020

Identifying turbulence features hindering swimming capabilities of grass carp larvae (Ctenopharyngodon idella) through submerged vegetation

Aquatic vegetation can provide habitat and refuge for a variety of species in streams. However, the flow features generated by submerged patches of vegetation can also pose a challenge for fish larvae. We conducted a series of experiments with live grass carp larvae (starting ∼50 h post hatch) in a laboratory racetrack flume, using a submerged array of rigid cylinders to mimic vegetation. We used particle image velocimetry to characterize the flow field, and particle tracking velocimetry to obtain position and displacement of the fish. Four speeds and two submergence ratios were investigated. In contrast with previous studies with grass carp eggs, our data showed an active response from larvae to determine their position. Our study shows that: (1) mean velocity by itself is not a reliable predictor, as some larvae will seemingly prefer to be in areas of higher speeds with lower shear and turbulence, (2) turbulence characteristics can be used to identify areas avoided by larvae, (3) turbulence length scales are relevant to determine spatial distribution of larvae and their swimming capabilities within and above vegetated patches and similar roughness elements in streams. These findings can inform the design of monitoring and control strategies in rivers based on turbulence and turbulence scales generated by natural and man-made instream structures.

Journal of Ecohydraulics↗

USGS2019

Influence of turbulence and in-stream structures on the transport and survival of grass carp eggs and larvae at various developmental stages

Understanding the response of grass carp to flow and turbulence regimes during early life stages is fundamental to monitoring and controlling their spread. A comprehensive set of hydrodynamic experiments was conducted with live grass carp eggs and larvae, to better understand their drifting and swimming patterns with 3 different in-stream obstructions: (1) a gravel bump, (2) a single cylinder, and (3) submerged vegetation. The hydrodynamic behavior of eggs and larvae with each obstruction was continuously monitored for about 85 consecutive hours. Transient spatial distributions of the locations of eggs and larvae throughout the water column were generated for each flow scenario. Results show that the active swimming capabilities of larvae allow them to seek areas of low turbulence and low shear stresses, and that eggs are susceptible to damage by high levels of turbulence, which was further corroborated with tests in an oscillating grid-stirred turbulence tank. Our study seeks to better inform field collection of grass carp during early life stages, and to guide the design of alternative approaches to control the dispersal of this invasive species in North America.

Aquatic Sciences↗

USGS2018

Survival and drifting patterns of grass carp eggs and larvae in response to interactions with flow and sediment in a laboratory flume

A series of laboratory experiments was conducted to better understand the behavior of grass carp eggs and larvae in moving water in order to develop and implement new strategies for control and prediction of their dispersal and drift at early life stages. Settling velocity and density of a representative sample of eggs were estimated, and three trials of flume experiments with different flow conditions were conducted with live eggs in a temperature-controlled setting with a mobile sediment bed. In these trials, egg and larval stages were continuously analyzed over periods of 80 hours; and eggs and larvae interactions with the flow and sediment bed were monitored and characterized qualitatively and quantitatively. Survival rates were quantified after each trial, highlighting physical causes for increased mortality. Detailed flow analysis was correlated to the observed drifting and swimming behavior of eggs and larvae, to estimate distributions across the water depth, as well as traveling and swimming speeds. Evidence of the influence of mean and turbulent flow in the suspension and transport of eggs are reported, and swimming patterns of larvae at different developmental stages are described. These findings support the development of new strategies for monitoring the spread of grass carp eggs and larvae in rivers, and provide new inputs to predict conditions favorable for spawning and hatching, allowing for mitigation measures at early life stages, which are critical to control their dispersal.

PLoS ONE↗