Impact of Dissolved Organic Carbon and Temperature on Phytoplankton Biomass in an Outdoor Study

Authors

• Ruaa Abass Lafta, Ministry of Higher Education and Scientific Research, Baghdad, IraqFollow
• Mohammed Hamdan, Department of Biology, College of Science for Women, University of Baghdad, Baghdad, IraqFollow

Abstract

Altered environmental conditions in aquatic ecosystems through Dissolved Organic Carbon (DOC) input and increased temperature influence phytoplankton communities. To assess the impacts of climate change as both single and combined effects of DOC inputs and temperature on phytoplankton growth, we conducted an outdoor experiment including four sets of conditions in triplicate: a) control, b) DOC treatment, c) temperature treatment, and d) DOC and temperature treatment. We added 10 mg/L of glucose (C₆H₁₂O₆) as a source of DOC. The warming treatment increased the water temperature by 3°C above the control (p-value < 0.05). The DOC treatment significantly affected pH, CO₂, and DOC (p-values = 0.004, 0.01, and 0.003, respectively). Dissolved oxygen was impacted by both DOC treatment (p-value = 0.0003) and temperature treatment (p-value = 0.003), whereas NO₃^-1 and PO₄^–3 were unaffected by either (p-value > 0.05). Both DOC and warming treatments significantly changed the physicochemical properties of the water, influencing phytoplankton biomass. The phytoplankton biomass(chl-a) showed significant positive correlations with temperature (r = 0.5, p-value = 0.0002), CO₂ (r = 0.64, p-value < 0.05), DOC (r = 0.6, p-value < 0.05), NO₃^-1 (r = 0.5, p-value < 0.05), and PO₄^–3(r = 0.5, p-value = 0.0001), while being negatively correlated with pH (r = –0.5, p-value = 0.001). Dissolved oxygen also showed a positive correlation with phytoplankton biomass (r = 0.63, p-value < 0.05). We concluded that increasing DOC input is crucial for mitigating the negative effects of warming on phytoplankton growth, as DOC provides a primary source of CO₂ necessary for photosynthesis.

Keywords

Aquatic environment, Biomass, Dissolved organic carbon, Phytoplankton, Temperature

Subject Area

Biology

Article Type

Article

First Page

1548

Last Page

1557

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

How to Cite this Article

Lafta, Ruaa Abass and Hamdan, Mohammed (2026) "Impact of Dissolved Organic Carbon and Temperature on Phytoplankton Biomass in an Outdoor Study," Baghdad Science Journal: Vol. 23: Iss. 5, Article 1.
DOI: https://doi.org/10.21123/2411-7986.5285