Fig 1.
Location of the sample sites and generalized salinity contours in Lagos Lagoon, Gulf of Guinea (Nigeria).
Salinity in Lagos Lagoon varies by season and location, with the freshest water being in the northern and the eastern portion of the lagoon. The salinity contours provided cover the range of seasonal variation [8, 10, 11]. Salt water entering the lagoon via the main Atlantic entrance channel and the Five Cowries Creek mingles with lagoon water and creates a brackish water environment with decreasing values towards the distal ends of the lagoon. The Osun River discharges its waters into Lekki lagoon, a large expanse of shallow freshwater situated to the east of Lagos Lagoon, and connected to it via a narrow corridor.
Table 1.
Sample site information including in situ measurements of depth, pH, Total Dissolved Solids (TDS) and sea surface temperature recordings and sediment type (CS = Coarse Sand; FS = Fine sand; SM = Silty Mud; M = Mud).
Fig 2.
Percent abundances of agglutinated, hyaline-perforate and miliolid foraminifera across the Lagos Lagoon.
Circle diagrams represent 100 percent of the total assemblage at the individual sites (for details see Table 2).
Table 2.
Quantitative faunal analyses of foraminiferal assemblages from the Lagos Lagoon, Southwest Nigeria, Gulf of Guinea.
Fig 3.
Heat maps showing color-coded percent abundances with interpolated distribution contours for A.) Ammotium salsum, B.) Trochammina sp. 1. and C.) Ammonia aoteana, within the Lagos Lagoon, Nigeria.
Fig 4.
Number of foraminifera per unit gram of sediment (FN) in the Lagos Lagoon.
Note consistently high values in the eastern sector medium to high values along the continuation of the Ogun River outflow.
Fig 5.
Map summarizing color-coded species richness values at each sampling location.
Table 3.
Thirteen (13) most frequent and abundant benthic foraminifera from the lagoon.
Fig 6.
Q-mode cluster analysis and distribution of cluster groups across Lagos Lagoon.
Fig 7.
Species dendrogram produced by the R-mode cluster analysis using the correlation coefficient matrix.
Note that R-mode clusters reflect test wall types (agglutinated versus hyaline-perforate/porcelaneous).
Fig 8.
PCA of the foraminiferal fauna of the Lagos Lagoon showing principal components 1 and 2 (A, B and R1, R2 refer to the assemblages defined in Figs 6 and 7).
Fig 9.
Detrended correspondence analysis of the benthic foraminiferal species recovered from the Lagos Lagoon (A, B and R1, R2 refer to the assemblages defined in Figs 6 and 7).
Fig 10.
Scanning electron micrographs of benthic foraminifera from the Lagos Lagoon: 1–7.
Ammotium salsum (Cushman and Brönnimann, 1948); scale bar for Fig 10.2 is 200 μm; 8, 9. Ammotium sp. 1; 10–12. Ammobaculites exiguus Cushman and Brönnimann, 1948; 13. Textularia candeiana d’Orbigny, 1839; 14–17. Textularia sp. 1; 18–20. Textularia sp. 2; 21, 22. Siphotextularia sp. 1; 23–26. Caronia exilis (Cushman and Brönnimann, 1948); scale bar for Fig 10.26 is 50 μm; 27–30. Milliamina fusca (Brady, 1870); 30–36. Trochammina sp. 1. Scale bar is 100 μm for all magnifications.
Fig 11.
Scanning electron micrographs of benthic foraminifera from the Lagos Lagoon: 1, 2.
Trilocularena patensis Closs, 1963; 3–5. Quinqueloculina debenayi Langer, 1992; 6–9. Quinqueloculina cf. Q. cuvieriana d’Orbigny, 1839; 10, 11. Quinqueloculina seminulum Linné, 1758; 12–14. Quinqueloculina cf. Q. seminulum Linné, 1758; 15, 16. Quinqueloculina cf. Q. vandiemeniensis Loeblich and Tappan, 1994; 17, 18. Quinqueloculina sp. 1; 19. Quinqueloculina sp. 2; 20. Quinqueloculina sp. 3; 21, 22. Quinqueloculina sp. 4; 23–27. Triloculina cf. T. verspertilo Zheng, 1988; 28. Pseudotriloculina sp. 1; 29, 30. Edentostomina sp. 1; 31, 32. Miliolinella sp. 1; 33–35. Neoeponides sp. 1. Scale bar is 100 μm for all magnifications, and 50 μm for Figs 11.2, 11.11, 11.15, 11.16, 11.24, 11.31, and 11.32.
Fig 12.
Scanning electron micrographs of benthic foraminifera from the Lagos Lagoon: 1–5.
Rosalina cf. R. orientalis (Cushman, 1925); 6–9. Hanzawaia cf. H. nipponica Asano, 1944; 10–13. Planulina sp. 1; 14–16. Nonion fabum (Fichtel and Moll, 1798); 17–19. Pararotalia sarmientoi (Redmond, 1953); 20–24. Elphidium sp. 1; 25–30. Cribroelphidium mirum Langer and Schmidt-Sinns, 2006; 31, 32. Porosononion sp. 1. Scale bar is 100 μm for all magnifications and 50 μm for Figs 12.10–12.13, 12.31 and 12.32.
Fig 13.
Scanning electron micrographs of benthic foraminifera from the Lagos Lagoon: 1, 2.
Rotorbis? sp. 1; 3, 4. Globocassidulina? sp. 1; 5, 6. Bolivina cf. B. persiensis Lutze, 1974; 7–9. Bolivina striatula Cushman, 1922; 10, 11. Bolivina sp. 1; 12, 13. Bolivina sp. 2; 14–16. Rectuvigerina phlegeri Le Calvez, 1959; 17–22. Ammonia convexa Collins, 1978; 23–27. Ammonia aoteana (Finlay, 1940); 28, 29. Cibicides pseudolobatulus Perelis and Reiss, 1975; 30. Amphistegina sp. 1. Scale bar is 100 μm for all magnifications and 50 μm for Figs 13.1, 13.2, 13.9 and 13.11.