Characterization of hydrological features and plankton during neap tides in a subtropical lagoon south of the California Current

ABSTRACT

This study aimed to characterize their Spatio-temporal distribution of hydrological variables and plankton during neap tides in Bahía Magdalena, a subtropical lagoon south of the California Current. We compare data from surface and bottom waters of stations located inside the lagoon with those near the bay's mouth and between surface and bottom. The availability of nutrients and the chlorophyll-a are associated primarily with the intense upwelling activity in spring. Due to direct marine influence, this relationship was more significant at the inlet than inside the lagoon, especially at the bottom. During the intense upwellings marine influence is maintained even during neap tides. The wind probably causes the homogeneous distribution in most variables within the bay's surface; this may also contribute to the re-suspension of nutrients due to vertical water column mixing. Abiotic variables were not linearly related with zooplankton biovolume and the density of diatoms and dinoflagellates. Phytoplankton was composed mainly by the micro fraction and diatoms during spring and nanoplankton in the warmest season of the year; however, the strong upwellings at the spring's end caused a HAB composed for diatoms. Chlorophyll-a concentration and diatoms were more abundant inside the lagoon and could explain the lower nutrient concentration of that zone. Zooplankton biovolume seasonality differed from other years, with higher values during winter and a significant decreasing trend throughout the year, resulting from the phytoplankton variability. Upwelling and wind variability explains the high biological productivity observed over most of the year.

KEYWORDS:

• Drivers
• coastal upwelling
• tides
• nutrients
• plankton
• Bahía Magdalena
• Mexico
• subtropical lagoon

Acknowledgments

The authors thank Mr. Roberto Flores, from Baja Seas Aquaculture, for logistical support and his valuable recommendations on the best way to carry out the samplings. Thanks to Ms. Araceli Avilés and Ms. Ma. del Carmen Leticia Suárez for their support during the sampling and to the administrative staff of the Centro Interdisciplinario de Ciencias Marinas, Instituto Politécnico Nacional (IPN) and the Instituto Nacional de la Pesca (INAPESCA). This study was supported by the IPN (SIP grant Multidisciplinary project 2020–2022) and INAPESCA. María Elena Sánchez-Salazar translated the manuscript into English.

Disclosure statement

No potential conflict of interest was reported by the author(s). In agreement with the disclosure statement.