Response of littoral epilithic communities to climate change: an in situ warming experiment

Date

2026-7-31

Author

Arıkan, Onat

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Global warming can alter the structure and functioning of aquatic ecosystems, yet the responses of benthic communities under field conditions remain poorly understood. This study developed an in situ heated settlement plate system to examine warming responses of littoral epilithic communities growing on natural travertine substrates. The performance of the system was evaluated through two preliminary field trials and refined before the experiment. The system consisted of eight heated, and eight non-heated plates regulated by an Arduino-based temperature-control system. During the 63-day experiment, heated plates maintained a mean warming offset of approximately +4.5 °C above non-heated plates. Epilithic biomass was quantified using chlorophyll-a, while respiration, net community production, and gross primary production were estimated from dissolved oxygen changes during dark and light incubations. Metabolic rates were expressed per unit surface area and per unit chlorophyll-a. Chlorophyll-a concentrations were similar between treatments on day 42 but were significantly lower in heated plates on day 63, with a significant overall heating effect (p = 0.048). Heating also significantly affected area-based and chlorophyll-a-normalized respiration (p = 0.003 and p = 0.011, respectively), with lower oxygen consumption in heated plates at the later sampling date. Net community production showed no significant overall response, while gross primary production showed weaker, non-significant changes. Overall, +4.5 °C warming altered epilithic biomass and community metabolism under field conditions. The main novelty of this study is the development of an in situ heated settlement plate system using natural travertine substrates, providing a new field-based approach to study climate-warming effects on littoral benthic communities.

Subject Keywords

Epilithic Communities, Heated Settlement Plates, in situ Warming, Chlorophyll-a, Community Metabolism

URI

https://hdl.handle.net/11511/120656

Collections

Graduate School of Marine Sciences, Thesis