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The present paper reports on a twenty six year monitoring of the diazotrophic cyanobacteria, Trichodesmium erythraeum in the Gulf of Gabes associated with environmental parameters and meteorological variables. Trichodesmium erythraeum blooms were not recurrent all years and were observed on average 2.11 times per year over the period between 1988 and 2013. Blooms were associated with temperature exceeding 24 degrees C and wind speed generally less than 5 m s(-1). Trichodesmium erythraeum reached very high densities fluctuating between 0.12 x 10(6) and 720 x 10(6) trichomes dm(-3). The wind speed during dust events and the number of dust days per year were highly correlated to Trichodesmium abundances. Two wind regimes during dust events were identified. The South-South East direction crossing the Tunisian desert generated the most intensive blooms. High dissolved inorganic nitrogen concentrations (2 - 14.6 mu M) and orthophosphate concentrations (0.05-2.79 mu M) were observed during bloom events leading to high N/P ratio well above the Redfield ratio and fluctuating linearly as function of Trichodesmium abundance. The anomalous N/P ratio could result from Trichodesmium erythraeum biological N-2 fixation and/or the contribution of atmospheric deposition. (C) 2016 Elsevier Ltd. All rights reserved.