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5 results on '"Assogba, Arnaud"'

3. Tidal Impacts on Zooplankton Dynamics in a Major Ocean-Lagoon Channel: Insights from a 25-Hour Intensive Survey in the Cotonou Channel, Benin.

Author

Akodogbo, Hervé Hotèkpo, Dossou-Sognon, Fridolin Ubald, Ouinsou, François Talomonwo, Avocegan, Thalasse Tchémangnihodé, Kouglo, Junior Patric, Okpeitcha, Olaègbè Victor, Assogba, Arnaud, Sohou, Zacharie, Morel, Yves, and Chaigneau, Alexis

Subjects
PEARSON correlation (Statistics), PRINCIPAL components analysis, SPECIES diversity, ANALYSIS of variance, ROTIFERA, LAGOONS
Abstract

This study investigates the effects of tidal cycles on the zooplankton community within the Cotonou Channel, an important waterway connecting the large Nokoué Lagoon to the Atlantic Ocean in Benin. From the determination of zooplankton composition from 25-hour samples collected in July 2020, alpha diversity indices and abundance were assessed, while relationships between biotic and abiotic parameters were analyzed through Pearson correlation, analysis of variance, and principal component analysis. A total of 66 zooplankton taxa were identified, with rotifers exhibiting the highest species richness (35 taxa), while copepods dominated in abundance (71%). Zooplankton abundance varied significantly, ranging from 2 to 95 ind L−1 depending on the tidal phase. A negative correlation was found between species richness (r = −0.51, p < 0.01) and increasing salinity (3–37), indicating that higher salinity reduced diversity (r = 0.06, p > 0.05). Resilient species like Synchaeta bicornis persisted despite salinity changes. The tidal cycle structurally altered the zooplankton community, with abundance and diversity peaking at different phases, notably higher at high tide (15 ind L−1.) These initial findings underscore the complex interactions between tidal dynamics and estuarine biodiversity, suggesting the need for further research across different tidal and seasonal conditions to inform effective management and conservation efforts. [ABSTRACT FROM AUTHOR]

Published
2024
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4. From seasonal flood pulse to seiche: Multi-frequency water-level fluctuations in a large shallow tropical lagoon (Nokoué Lagoon, Benin)

Author

Chaigneau, Alexis, primary, Okpeitcha, Olaègbè Victor, additional, Morel, Yves, additional, Stieglitz, Thomas, additional, Assogba, Arnaud, additional, Benoist, Morgane, additional, Allamel, Pierre, additional, Honfo, Jules, additional, Awoulmbang Sakpak, Thierry Derol, additional, Rétif, Fabien, additional, Duhaut, Thomas, additional, Peugeot, Christophe, additional, and Sohou, Zacharie, additional

Published
2022
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5. From seasonal flood pulse to seiche: Multi-frequency waterlevel fluctuations in a large shallow tropical lagoon (Nokoué Lagoon, Benin)

Author

Chaigneau, Alexis, Okpeitcha, Victor, Morel, Yves, Stieglitz, Thomas, Assogba, Arnaud, Benoist, Morgane, Allamel, Pierre, Honfo, Jules, Derol, Thierry, Sakpak, Awoulmbang, Rétif, Fabien, Duhaut, Thomas, Peugeot, Christophe, Sohou, Zacharie, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Seiches, Wavelet analysis, Tides, Nokoué, Water-levels, Lagoons
Abstract

This study investigated the main water-level (WL) variability modes of Nokoué Lagoon in Benin (West-Africa). The average WL ranges between 1.3 and 2.3 m between the low-and high-water seasons. Seasonal as well as weak interannual variations between 2018 and 2019 are driven by rainfall regime over the catchment and associated river inflow. At sub-monthly scales, the lagoon is tidally choked: ocean tides can reach 90 cm, whereas in the lagoon semi-diurnal and diurnal tides hardly reach few centimeters. Choking conditions vary with river inflow and ocean tide amplitude, correctly represented by a simple tidal choking model. Diurnal modulation and asymmetry of the tide are stronger (weaker) during high (low) water period. We also observed WL variations of ±5-10 cm at a fortnightly frequency, stronger during wet (high-water) season. Superimposed on the seasonal, fortnightly and tidal WL variations, we further observed short-term high-frequency seiche events. Mostly observed during dry (low-water) conditions, they are characterized by typical standing-wave oscillations of 5-10 cm amplitudes and 3 h periods. They are forced by the passage of fast-moving squall-lines that induce strong wind variations, heavy rainfalls and rapid drop-off of the air temperature. Results obtained in this study provide useful metrics for the validation of flood forecasting models to be implemented in Benin, and elsewhere on the West African coastline.

Published
2021

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