1,2,1,1- 1Istanbul Technical University, School of Civil Engineering, Department of Environmental Engineering, Istanbul, Türkiye (onaymuh@itu.edu.tr, elif.pehlivanoglu@itu.edu.tr, burcak.kaynak@itu.edu.tr)
- 2Gebze Technical University, School of Engineering, Department of Environmental Engineering, Kocaeli, Türkiye (serrasaracoglu@gtu.edu.tr)
The Mediterranean is one of the most nutrient-poor marine areas in the world, where the spatial and temporal changes in phytoplankton is difficult to capture due to the limited in-situ measurements, particularly across the Eastern Mediterranean. In this context, satellite-based remote sensing with increasing spatial resolution provides phytoplankton-related indicators, among which the most widely used is chlorophyll-a (Chl-a) for assessing phytoplankton biomass and eutrophication status of aquatic ecosystems. Chl-a levels in this region are shaped by both natural nutrient inputs, such as dust transport and wildfires, and anthropogenic influences, including terrestrial nutrient discharge. While the influence of episodic wildfire and dust transport on enhancing Chl-a has been investigated in this study, busy and increasing shipping activity of the region raised additional questions regarding its potential contribution to Chl-a levels, including an episode investigating the operations of livestock carriers. The livestock episode showed more local Chl-a enhancements around the shipping routes compared to wildfire and dust transport.
In this study, satellite-derived GCOM-C/SGLI Chl-a observations and high-resolution EMODnet shipping route density data were used for a five-year (2019-2023) spatio-temporal assessment across the Eastern Mediterranean, covering open-sea regions. The aim is to investigate the effect of maritime activity on phytoplankton dynamics through a route-based evaluation of shipping-intense areas first time in the literature.
Across the five-year period, Chl-a levels showed coastal-open sea contrast and strong seasonality in the region, while episodic investigations showed that wildfires and dust transport can trigger short-term but large-area increases. In the Eastern Mediterranean, open-sea areas with high shipping intensity showed systematically elevated Chl-a levels, and the novel grid-based percentile method developed showed that a significant correlation between high route density and increased Chl-a levels, particularly during the periods of limited phytoplankton growth. This relationship was statistically significant, with high-intensity shipping grids (≥75th percentile) showing higher Chl-a levels than low-intensity grids (≤25th percentile) across most months, especially from May to October. As the percentile levels increase from ≥75th to >99th percentile, Chl-a levels increased almost linearly. These findings proved that shipping activity play an important, and previously overlooked role in phytoplankton dynamics in the open-sea regions of the Eastern Mediterranean, further indicating the need to better quantify and manage contribution of shipping sector to algal growth.
Keywords: Chl-a; Eastern Mediterranean; Livestock Carrier; Shipping
How to cite: Saracoglu, S., Onay, M. G., Pehlivanoglu, E., and Kaynak, B.: Spatio-temporal changes of chlorophyll-a over the Eastern Mediterranean: A novel high-resolution methodology for investigating the possible impact of shipping sector, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-954, https://doi.org/10.5194/egusphere-egu26-954, 2026.
