Ecological Geography of the Phytoplankton Associated to Bio-Optical Variability and HPLC-Pigments in the Central Southwestern Gulf of Mexico
An oceanographic cruise with 34 stations was conducted in the central-southwestern region of the Gulf of Mexico from February 19 to 10 March 2013. This study included the measurement of hydrographic and phytoplankton bio-optical parameters, and pigment samples were collected at two depth levels (10...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-06-01
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| Series: | Journal of Marine Science and Engineering |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2077-1312/13/6/1128 |
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| Summary: | An oceanographic cruise with 34 stations was conducted in the central-southwestern region of the Gulf of Mexico from February 19 to 10 March 2013. This study included the measurement of hydrographic and phytoplankton bio-optical parameters, and pigment samples were collected at two depth levels (10 and 50 m). Our results showed a warm and nutrient-depleted water column associated with low chlorophyll a (<1 mg Chla m<sup>−3</sup>) and average values of a<sub>ph</sub>440 (0.01 ± 0.008, m<sup>−1</sup>) and a<sub>d</sub>350 (0.04 ± 0.02, m<sup>−1</sup>). In addition, nano-microphytoplankton abundance and pigments were analyzed using a light microscope and HPLC, respectively. Overall, the Gulf of Mexico exhibited oligotrophic characteristics, with Chla (0.17 ± 0.11 mg m<sup>−3</sup>) and NO<sub>3</sub><sup>−</sup> (0.03 ± 0.001 µM), except at 50 m depth in some stations north of Yucatán and in Campeche Bay and at surface level off the Tamaulipas shelf. In these three regions, values of a<sub>ph</sub>(440), a<sub>d</sub>(350), (Chla) and phytoplankton abundance (>12 × 10<sup>3</sup> cells L<sup>−1</sup>) were observed near river mouths and under seasonal oceanographic forcings, which increased the growth and diversity of phytoplankton. The most relevant pigments found were DVchla (0.06 ± 0.13 mg m<sup>−3</sup>), Chlb (0.16 ± 0.21 mg m<sup>−3</sup>), Zea (0.06 ± 0.03 mg m<sup>−3</sup>), and Hex-fuco (0.02 ± 0.02 mg m<sup>−3</sup>); these are associated with the presence of <i>Prochlorococcus</i>, chlorophytes, <i>Synechococcus</i>, prymnesiophytes, and diatoms. Through the bio-optical variability, we determined the ecological geography of phytoplankton in four different spectral shapes, where M1 and M2 represent the group of cyanobacteria (<i>Prochlorococcus</i> and <i>Synechococcus</i>) and M3 and M4 represent a mixture of diatoms, dinoflagellates, and chlorophytes. In conclusion, we consider that oceanographic processes such as cyclonic and anticyclonic structures and permanent rivers determine the favorable changes in phytoplankton (>nutrients, Chla, a<sub>ph</sub>440) and an increment in the number of phytoplankton spectral shapes). |
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| ISSN: | 2077-1312 |