Development of bubble screen barriers for controlling dispersal of invasive carp eggs and larvae in streams

Prasad, Vindhyawasini

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https://hdl.handle.net/2142/127503 Copy

Description

Title

Development of bubble screen barriers for controlling dispersal of invasive carp eggs and larvae in streams

Author(s)

Prasad, Vindhyawasini

Issue Date

2024-12-05

Director of Research (if dissertation) or Advisor (if thesis)

Tinoco, Rafael Omar

Doctoral Committee Chair(s)

Tinoco, Rafael Omar

Committee Member(s)

• Garcia, Marcelo H.
• Suski, Cory D.
• Jackson, Patrick Ryan
• Zielinski, Daniel

Department of Study

Civil & Environmental Eng

Discipline

Civil Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

Invasive carp, bubble screen, multiphase flows, environmental fluid mechanics, flow-particle interactions

Abstract

This study proposes a novel application of oblique bubble screens (OBS) as a potential deterrent for downstream drifting eggs and larvae of invasive carp. The study is divided in four stages: (1) initial characterization of particle-OBS interactions, (2) assessment of OBS effect on live grass carp eggs and larvae, (3) characterization of surrogates to accurately mimic live egg response, and (4) refining of OBS design for increased capture efficacy 1. The efficacy of various OBS configurations at redirecting downstream drifting particles was initially tested with fish egg surrogates of a wide range of physical properties, including negatively buoyant (NB), positively buoyant (PB) and semi-buoyant (SB) particles. The OBS could successfully redirect PB, NB and SB to pre-determined target locations for their capture. The redirection was facilitated by the OBS-induced lateral push, characterized through detailed hydrodynamic measurements around the OBS. The effects of airflow rate, mean flow velocity and inclination angle of the diffusers on the redirection efficiency were investigated. 2. Selected OBS configurations were used to assess redirection of live eggs and larvae at different developmental stages, from pre- to near-gas bladder inflation (GBI). The study showed lower egg capture rates than NB, PB, and SB particles, primarily due to nearly neutrally buoyant behavior of the eggs which lead to inconsistent responses to the recirculation induced by the OBS. The studies with live larvae revealed an active response from post-GBI larvae, particularly at low flow velocities. The hydrodynamic study allowed us to identify large-scale OBS-generated motions as the drivers of the spatial distribution patterns observed for eggs, pre-GBI larvae, post-GBI larvae, and dead larvae. 3. To overcome the limitations of using live grass carp eggs in laboratory experiments (e.g., their seasonal availability which limits year-round access, their 1-day hatching time which limits the number of experimental conditions which can be tested during the egg stage, and their fragility, which limits the flow conditions and handling required to avoid ruptured membranes), we developed surrogates to closely replicate live carp egg movement. Plastic beads with adjusted weights and formalin-preserved eggs were tested in settling column experiments and used to study the efficacy of a broad range of OBS configurations to confirm the surrogates’ ability to closely mimic the behavior of grass carp eggs in a highly turbulent environment. 4. Given low capture rates of eggs with OBS configurations, the approach was modified by placing the diffuser parallel to the mean flow aligned with the flume centerline and aiming for capturing particles along the flume walls. The modified approach generated helical motions which yielded a high capture efficiency. Five different grass carp life-stages were tested: live eggs, pre-GBI larvae, post-GBI larvae, dead larvae and eggs preserved in formalin. Capture efficacy remained consistent across all stages and was determined to be a function of airflow rate for a given flow speed. Compared to lower velocities, achieving equivalent capture efficacy at higher flow velocities required increased airflow rates and an extended side net coverage. We defined a timescale associated with one recirculation of the helical motion and estimated the effective length of the target nets to achieve a given capture rate. The study showed the potential of oblique bubble screens (OBS) as a novel tool for controlling the spread of invasive carp in streams. By strategically modifying the hydrodynamic field, OBS can effectively redirect and capture drifting eggs and larvae, offering a promising approach for mitigating the ecological impact of invasive species. This technology can be fine-tuned to target specific fish species based on their physical properties, allowing it to be implemented in various aquatic environments to help protect native ecosystems and biodiversity.

Graduation Semester

2024-12

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/127503

Copyright and License Information

Copyright 2024 Vindhyawasini Prasad

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