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2 2025

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Climate change and its effects on marine food web with the concentration of pelagic fishes in the northern Arabian Sea

Kashani Imtiaz, Panhwar Sher Khan, Kachhi Kishwar Kumar

Oceanologia

2025

No. 67 (1)

Art. no. 67110

The northern Arabian Sea, a vital ecosystem that sustains a significant population through its fisheries is increasingly threatened by climate change, overharvest, and coastal pollution. To evaluate the combined effects of these pressures on fishery health, microplankton, fish bycatch, and coastal environment data were examined between 2019 and 2023 from key hotspots. Using the time-cumulated indicator (TCI) and efficiency cumulated indicator (ECI) approaches, we aimed to determine broader spectrum of energy flow in the ecosystem. The findings revealed a delicate equilibrium in the ecosystem. Although average temperatures remained stable, variations in rainfall patterns suggested potential changes in salinity and dissolved oxygen levels, signaling subtle climate change influences. Biological indicators highlighted dynamic shifts: species diversity fluctuated, suggesting community restructuring, while increased evenness implied potential ecological stabilization. The production and biomass (P/B) ratio was higher in 2019, reflecting faster biomass production compared to the slower rate observed in 2023. This instability may be attributed to environmental changes, altered species composition, and a steady increase in fishing pressure. Notably, consistent fish catches amidst relatively stable species diversity suggest complex population dynamics. In terms of energy flow and transformation, a significant rise in TCI, suggests accelerated energy transfer, likely driven by a decline in predator population. Additionally, the instability in Residence Time (RT) underscores intricate food web interactions. Our findings highlight the delicate equilibrium of the northern Arabian Sea, as revealed by the overall data and assessment. Understanding these intricate dynamics is crucial for developing effective conservation strategies and promoting sustainable fishing practices.

Carbonaceous aerosol particle sources in Manila North Port and the urban environment

Gill Touqeer, Kecorius Simonas, Kandrotaitė Kamilė, Dudoitis Vadimas, Madueño Leizel, Wiedensohler Alfred, Poulain Laurent, Vallar Edgar A., Galvez Maria Cecilia D., Byčenkienė Steigvilė, Plauškaitė Kristina

Oceanologia

2025

No. 67 (1)

Art. no. 67109

This study addresses the pressing issue of black carbon (BC) pollution in urban areas, focusing on two locations in the Philippines: Quezon City’s East Avenue (QCG, roadside urban environment) and Manila’s North Port. We found that organic aerosol particles (OA) made a greater contribution (80%) to total submicron particulate matter compared to inorganic aerosol (IA) (20%). The mean hourly average equivalent black carbon (eBC) mass concentration at the QCG site (35.97 ± 16.20 𝜇g/m3) was noticeably higher compared to the Port (10.27 ± 5.99 𝜇g/m3), consistent with trends in other Asian cities. Source apportionment analysis identified eBC related to transport emissions (eBCTR) as the predominant contributor to eBC, accounting for 86% at the Port and 80% at QCG. Diurnal patterns showed the highest eBCTR mass concentrations (47.69 ± 9.34 𝜇g/m3) during morning rush hours, which can be linked to light-duty vehicles. Late-night (10 pm–12 am) high concentrations (30.63 ± 8.45 𝜇g/m3) can be associated with heavy diesel trucks at the QCG site. Whereas at the Port site, hourly average higher eBCTR concentration (12.24 ± 3.65 𝜇g/m3) during morning hours (6 am–8 am) can be attributed to the traffic of heavy-duty trucks, trollers, diesel-powered cranes and ships. Compared to the QCG site, a lower eBC concentration at the Port site was favoured by the more open environment and higher wind speed, facilitating better pollutant dispersion. The mean hourly average concentrations of PM2.5 and PM10, measured using an Aerodynamic Particle Sizer, consistently exceeded the air quality standards set by the World Health Organization and the Philippine Clean Air Act at both sites. This study highlights the persisting BC pollution in developing regions and calls for scientifically based strategies to mitigate the air quality crisis.