About

Gaby Markle ’26 is a student involved in research related to improving therapeutics for Type 1 diabetes through synthetic biology, working with Cornell CALS biological and environmental engineering professor Minglin Ma. Her work focuses on developing potential treatments for diabetes, exemplifying the department's emphasis on innovative biological research. The department of Molecular Biology and Genetics at CALS offers a variety of research opportunities, supporting students in conducting groundbreaking work that contributes to advancements in health and environmental sciences. The department's research efforts are part of CALS's broader mission to bring new thinking and solutions to major challenges in agriculture, environment, and health.

Research topics

• Agronomy
• Environmental science
• Biology
• Ecology
• Environmental engineering
• Horticulture
• Materials science
• Chemistry
• Pulp and paper industry
• Engineering
• Fishery

Selected publications

• Can domestic aquaculture compete? Consumer willingness to pay and cost benchmarks in the Arabian peninsula

  Open MIND · 2026-01-01

  article

  In countries with limited water resources that increasingly rely on imported food, sustainable fish farming offers a promising pathway to improve food security. This study focuses on Saudi Arabia, an arid country prioritizing domestic aquaculture expansion under its Vision 2030 initiative, and investigates consumer preferences for domestically farmed rainbow trout (<i>Oncorhynchus mykiss</i>) as a viable substitute for imported salmon. Using a discrete choice field experiment at point-of-sale with 333 consumers in Riyadh and Jeddah, we estimate willingness-to-pay (WTP) for key rainbow trout attributes, including origin, certification, product form, processing method, and color. Results show strong preferences for domestically produced, SAMAQ-certified (a national aquaculture quality label), fresh fillets with orange color, and significant WTP premiums for these traits. We also compare these WTP estimates with production cost scenarios to assess the economic feasibility of substituting imported salmon with domestically farmed rainbow trout. Findings suggest that, under efficient production scales, domestically produced trout can be cost-competitive with imports when aligned with consumer preferences. This study contributes new evidence from an arid, import-dependent country and highlights how aligning supply with consumer demand can support aquaculture expansion. The results offer practical guidance for food system transformation in similar contexts globally.

  DOI

• Can domestic aquaculture compete? Consumer willingness to pay and cost benchmarks in the Arabian peninsula

  Aquaculture Economics & Management · 2026-02-23

  article
  PublisherDOI

• Can domestic aquaculture compete? Consumer willingness to pay and cost benchmarks in the Arabian peninsula

  Figshare · 2026-01-01

  articleOpen access

  In countries with limited water resources that increasingly rely on imported food, sustainable fish farming offers a promising pathway to improve food security. This study focuses on Saudi Arabia, an arid country prioritizing domestic aquaculture expansion under its Vision 2030 initiative, and investigates consumer preferences for domestically farmed rainbow trout (<i>Oncorhynchus mykiss</i>) as a viable substitute for imported salmon. Using a discrete choice field experiment at point-of-sale with 333 consumers in Riyadh and Jeddah, we estimate willingness-to-pay (WTP) for key rainbow trout attributes, including origin, certification, product form, processing method, and color. Results show strong preferences for domestically produced, SAMAQ-certified (a national aquaculture quality label), fresh fillets with orange color, and significant WTP premiums for these traits. We also compare these WTP estimates with production cost scenarios to assess the economic feasibility of substituting imported salmon with domestically farmed rainbow trout. Findings suggest that, under efficient production scales, domestically produced trout can be cost-competitive with imports when aligned with consumer preferences. This study contributes new evidence from an arid, import-dependent country and highlights how aligning supply with consumer demand can support aquaculture expansion. The results offer practical guidance for food system transformation in similar contexts globally.

  PublisherDOI

• Evaluation of Fish Biosolids as a Fertilizer for Organic Tomato Transplant Production

  Horticulturae · 2025-01-08

  articleOpen access

  Interest among consumers in the availability of organically produced fruits and vegetables is increasing. Seafood demand is increasingly being met by fish raised using aquaculture methods that provide fish excretory products that can meet organic standards for nutrient sources for organic vegetables. We conducted an experiment in a glass greenhouse to evaluate fish biosolids as a substrate amendment for organic tomato transplant production. We compared the fish biosolids treatment to several different organic fertilizers, along with a commonly used inorganic slow-release fertilizer (Osmocote). All treatments used a target N concentration of 400 mg/L incorporated into the substrate and we also included fish biosolids treatments of 200 and 800 mg N/L. Plant performance was monitored for 4 weeks starting with commercially available 2-week-old seedlings. The results showed that the 800 mg N/L fish biosolids treatment compared very favorably with the conventional Osmocote treatment at the conclusion of the trial. The 800 mg N/L fish biosolids treatment exceeded the Osmocote treatment for chlorophyll content and for leaf number for the first 3 weeks of the 4-week trial. Grower management protocols could further improve seedling performance by providing additional top dressings of fish biosolids or fish effluent waters as plants age.

  PublisherOA PDFDOI

• Geologic Mapping in New Mexico: An Update on the New Mexico STATEMAP Program

  Proceedings volume ... annual spring meeting · 2024-04-16

  articleOpen access
  PublisherOA PDFDOI

• Evaluation of Fish Biosolids as a Growth Media Component for Organic Tomato Transplant Production

  Preprints.org · 2024-11-04

  preprintOpen access

  Interest among consumers is increasing for the availability of organically produced fruits and vegetables. Seafood demand is increasingly being met by fish raised using aquaculture methods that provide fish excretory products that can meet organic standards for nutrient sources for organic vegetables. We conducted an experiment in a glass greenhouse to evaluate fish biosolids as a growth media component for organic tomato transplant production. We compared the fishbiosolids treatment to several different organic fertilizers along with a commonly used inorganic slow-release fertilizer (Osmocote). All treatments used a target N concentration of 400 mg/L incorporated into the substrate and we also included fish biosolids treatments of 200 and 800 mg/L. Plant performance was montiored for 5 weeks starting with commercially available 2-week old seedlings. Results showed that the 800 mg/L fish biosolids treatment compared very favorably with the inorganic Osmocote treatment at the conclusion of the trial. The 800 mg/L fish biosolids treatment exceeded the Osmocote treatment for chlorophyll content and for leaf number for the first 4 weeks of the 5 week trial. Grower management protocols could further improve seedling performance by providing additional top dressings of fish biolsolids or fish effluent waters as the plants age.

  PublisherOA PDFDOI

• A Predictive Model of Nutrient Recovery from RAS Drum-Screen Effluent for Reuse in Aquaponics

  Horticulturae · 2023 · 7 citations

  Senior authorCorresponding
  • Environmental science
  • Environmental engineering
  • Pulp and paper industry

  Controlled environment agriculture (CEA) optimizes growth parameters for vegetable and aquaculture production and can be used to address growing global food insecurity. Recirculating aquaculture systems (RAS) generate a nutrient-dense effluent that may result in environmental pollution, but with treatment and integration with hydroponic vegetable production may be repurposed as a naturally derived nutrient solution. This work developed a preliminary model using the system feed rate to calculate a plant-essential nutrient discharge rate in RAS effluent. Loading rate equations were created to calculate the daily mass of nutrients entering the system through fish feed, and discharge rate equations were created to calculate the grams of each nutrient discharged in the effluent per kilogram of feed. Data from previous published work were used for validation. The loading-rate percentage discharged for nutrients present in the effluent was between 2.71% and 64.5%, with several nutrients being prominent pollutants and all being required for vegetable growth. This work provides the preliminary framework for calculating nutrient discharge rates, which can be used to mitigate pollution or develop more precise, naturally derived hydroponic nutrient solutions for a circular bioeconomy in CEA.

  PublisherOA PDFDOI

• Complementary Nutrients in Decoupled Aquaponics Enhance Basil Performance

  Horticulturae · 2022 · 29 citations

  • Agronomy
  • Horticulture
  • Environmental science

  Aquaponics combines raising fish and growing plants by recycling water and nutrients to reduce water consumption and reliance on chemical fertilizers. Coupled aquaponics systems recirculate water between fish and plant crops, whereas decoupled systems send mineralized fish effluent and wastewater unidirectionally to an independent hydroponic loop. Decoupling enables changes to the water, such as pH adjustments and complementary nutrient additions, to promote plant performance. In this study, basil, Ocimum basilicum (L.), was transplanted into 4 L containers filled with decoupled aquaponic (DAP), nutrient-complemented decoupled aquaponic (DAP+), or chemical-based conventional hydroponic (CON) nutrient solutions and grown for 21 days at pH 5.8. Plants grown in DAP+ and CON had greater biomass, height, and Soil Plant Analysis Development (SPAD) chlorophyll index and lower root:shoot biomass ratios than those in DAP. Shoot fresh and dry biomass was 11% greater for CON than DAP+, while height, SPAD chlorophyll index, and root:shoot ratio did not differ. We concluded that added nutrients in DAP+ enhanced performance compared to DAP, and the biologically derived nutrition in DAP+ enhanced performance to be similar, but not equal, to CON. We cannot recommend specific adjustments to the targeted blend of complementary nutrients tested, but findings suggest that complementary nutrients are effective in decoupled aquaponics.

  PublisherOA PDFDOI

• Quality, Yield, and Biomass Efficacy of Several Hydroponic Lettuce (Lactuca sativa L.) Cultivars in Response to High Pressure Sodium Lights or Light Emitting Diodes for Greenhouse Supplemental Lighting

  Horticulturae · 2020 · 32 citations

  • Horticulture
  • Agronomy
  • Environmental science

  Lettuce is an economically important crop that can be grown either in the field or greenhouse. Different challenges are present in either environment; therefore, cultivar selection is important. For hydroponic greenhouse lettuce there is relatively little published information on cultivar selection under different lighting sources. The objective of phase 1 was to determine the influence of lighting using high pressure sodium (HPS) or light emitting diodes (LED) on plant fresh weight, height, tip burn index, bolting, and Brix. Phase 2 was similar to phase 1 but with fewer cultivars (1) to allow for greater number of replicates per treatment per crop cycle. Each experiment consisted of three crop cycles over time per phase. Light sources were controlled using an algorithm, Light and Shade System Implementation (LASSI), to achieve a constant average daily light integral under each treatment and crop cycle. Electrical consumption and efficacy (fresh weight per kWh) from each treatment was estimated using data collected on power consumption from representative lamps multiplied by the number of fixtures and the hours fixtures were on per crop cycle. In phase 1, the fresh weight of 2 to 3 cultivars was greater under HPS and 1 to 2 cultivars under LED, depending on production cycle. The HPS-grown lettuce tended to have more tip burn and bolting in crop cycles 1 and 2, with cycle 3 showing similar tip burn incidence. Bolting was only consistently observed in one cultivar, ‘Teodore’. The LED array used less than half as much electricity as the HPS array, while producing relatively similar size lettuce, therefore, leading to electrical efficacies two- to three-times higher in LED than in HPS treatments. In phase 2, significant differences in height were found in ‘Greenstar’ and ‘Xandra’, with HPS producing larger plants than LED. Significant differences were also found in diameter in ‘Greenstar’, ‘Xandra’, ‘Locarno’, and ‘Crunchita’, with HPS again being larger than LED.

  PublisherOA PDFDOI

• Root nitrification capacity of lettuce plants with application to aquaponics

  Aquacultural Engineering · 2019-06-28 · 14 citations

  articleSenior authorCorresponding
  PublisherDOI

Frequent coauthors

• Richard S. Gates

  Iowa State University

  23 shared

• G. R. Baughman

  19 shared

• Rhett L. Weiss

  Cornell University

  16 shared

• Daniel P. Loucks

  16 shared

• John R. Callister

  Cornell University

  16 shared

• R. W. Bottcher

  14 shared

• James M. Ebeling

  Systems Technology (United States)

  14 shared

• James J. Bisogni

  Cornell University

  12 shared

Education

• PhD, Biological & Environmental Engineering

  Cornell University

  1979

Awards & honors

• Meritorious Service Award (2010)
• Aquacultural Engineering Society J. Thomas Clark Professor o…