Variação temporal da produtividade primária, nitrato, sílica e dióxido de carbono em relação a temperatura superficial do Mar (de 1993 – 2022) no Canal de Moçambique

Abstract

The study of the impact of climate change on the variation of PP, NO₃⁻, Si, and CO₂ is essential for understanding the functioning of marine ecosystems and the conservation of marine biodiversity. The present study aims to analyze the temporal variation of primary productivity, nitrate, silica and carbon dioxide in relation to Sea Surface Temperature (from 1993 – 2022) in the Mozambique Channel. highlighting the importance of understanding these dynamics for the conservation and management of marine ecosystems in the Mozambique Channel. Data on PP, NO₃⁻, Si, CO₂, and TSM were analyzed, obtained from the Copernicus Marine Environmental Monitoring Service (CMEMS) for the period from 1993 to 2022, totaling 30 years. The analysis was conducted through simulations using the BIORYS numerical model. The results revealed strong seasonality for all five parameters over the three decades studied. Generally, higher concentrations of PP, NO₃⁻, Si, CO₂, and TSM were observed in summer, with lower concentrations in winter, except for Si, which showed similar concentrations in the third decade. PP remained constant across all decades. In summer, NO₃⁻ varied, with higher concentrations in the second decade compared to the first and third. In winter, concentrations remained stable over the decades. Si levels in summer remained constant, while in winter, there was variation, with higher concentrations in the third decade compared to the first two. CO₂ levels varied over the decades: in summer, the highest concentrations occurred in the second and third decades compared to the first, and in winter, the highest concentration was in the third decade relative to the first two. TSM also varied over the decades: in summer, the highest concentrations were in the second and third decades compared to the first, and in winter, the highest concentration was in the third decade relative to the first two. PP and NO₃⁻ showed non-uniform interannual variations with a decreasing trend, reaching maximum peaks in 1994 (~7 mg/m³/day) and 2002 (0.2 mmol/m³), respectively. Si exhibited a uniform interannual variation with a decreasing trend, peaking in 1993 (3.5 mmol/m³). CO₂ showed a uniform increasing trend, reaching a maximum peak in 2022 (~40 Pa). TSM displayed a non-uniform increasing trend, with the highest peak in 2020 (26.83°C). The relationship between TSM and PP indicates a strong negative correlation (r = -0.74); between TSM and NO₃⁻, a moderate negative correlation (r = -0.53); between TSM and Si, a moderate negative correlation (r = -0.62); and between TSM and CO₂, a moderate positive correlation (r = 0.63). The study demonstrated that climate change influences the variation of PP, NO₃⁻, Si, and CO₂ in the Mozambique Channel.