Effects of physicochemical and sediment–mineral dynamics on phosphorus concentration and biological productivity in Lagos coastal waters

• Published in: Aquatic sciences Vol. 85; no. 3; p. 67
• Main Authors: Echebiri, Folake O., Abayomi, Akeem A., Oladosu, Najeem O., Ayeni, Amidu O., Adesalu, Taofikat A., Olayinka, Kehinde O., Alo, Babajide I.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-07-2023; Springer; Springer Nature B.V
• Subjects: Algae; Aluminum phosphate; Analysis; Aquatic plants; Berlinite; Bioavailability; Biodiversity; Biomedical and Life Sciences; Chlorophyll; Chlorophyll a; Coastal waters; Diffraction; Dynamics; Ecology; Environmental Management; Eutrophication; Freshwater & Marine Ecology; Life Sciences; Littoral environments; Marine & Freshwater Sciences; Mineral nutrients; Mineralogy; Molybdenum; Nutrient availability; Nutrient enrichment; Nutrient release; Oceanography; Perturbation; Phosphates; Phosphorus; Physicochemical processes; Plant growth; Rainy season; Regeneration (biological); Research Article; Sediment; Sediment samplers; Sediment samples; Sediments; Spectrophotometry; Water circulation; Water column; Wet season; X-ray diffraction; X-rays; Green algae; Coastal waters; Dissolved oxygen; Water temperature; Berlinite phosphorus; Effluent
• ISSN: 1015-1621; 1420-9055
• DOI: 10.1007/s00027-023-00965-9

African coastal waters provide important socioeconomic functions to littoral settlements; however, progressive nutrient enrichment of the waters has impacted negatively on them. This study identified the dynamics influencing eutrophication in Lagos coastal waters. The water column was sampled at two depths (5 cm and 2 m) and sediment samples were collected from 26 locations from November–December 2019 to January–March and August–October 2020. The various phosphorus species were determined by molybdenum blue spectrophotometry. Chlorophyll
a
was determined using pigment extraction -spectrophotometry. Phosphate mineralogy of sediment was determined using X-ray diffraction. The results showed that reactive P concentration ranged from 0.02 to 0.40 mg L
−1
across the water layers, while chlorophyll
a
was between 10.7 and 57.4 µg L
−1
. Sediment bioavailable P was 2.61 to 43.4 mg kg
−1
, while berlinite-P ranged from 17.3 to 96.6 g kg
−1
. The high level of bioavailable P, above the threshold for plant growth, showed that sedimentary P might act as a source of internal loading and that the berlinite mineral (AlPO
4
) content of sediments influenced the ability of sediment to act as a sink or source of P in the coastal water system. The results also showed that nutrient availability and release from sediment were influenced by water physicochemical conditions The significance of the positive associations between the green algae and the water -column P species was more prominent in the wet season. There is a need to develop regulatory tools to reduce human perturbations in these waters, which will in turn enhance the recovery and regeneration of the biodiversity of these waters.