This paper presents the results of studies into the use of the emerging techniques of nutrient induced fluorescence transients (NIFTs) and Fourier Transform InfraRed (FTIR) spectroscopy to determine the nutrient status of microalgae. Four species of microalgae were grown under conditions where growth rate was P-limited or P-replete, and NIFT responses and FTIR spectra in response to the re-supply of P (as PO 4 3-) measured. These responses were compared to more conventional measures of algal nutrient status such as P-uptake rates, P quotas and transient effects of PO 4 3-on oxygen exchange. The NIFT technique and FTIR spectroscopy gave results that were consistent with those obtained by the other techniques. Furthermore, we were able to demonstrate NIFT responses in phytoplankton samples taken from Lake Lucerne (total ambient P ≤ 0.13 µM) but not from Lake Zürich (total P 0.55 µM). The potential and limitations of the various techniques are discussed.

A total of 18 species of silica-scaled chrysophytes (Chrysophyceae: one species each in Chrysosphaerella, Spiniferomonas, and Paraphysomonas; Synurophyceae: 11 Mallomonas spp. and four Synura spp.) was recorded from river samples collected in Edo State, Benin, Nigeria, from both dry and rainy seasons in 2003. Identifications were based on transmission electron microscopy. Five are new records for Nigeria, including four being newly reported for Africa. Two further species could not be identified.

Algal toxins may accumulate in fish and shellfish and thus cause poisoning in consumers of seafood. Such toxins and the algae producing them are regularly surveyed in many countries, including Europe, North America, Japan and others. However, very little is known regards the occurrence of such algae and their toxins in most African countries. This paper reports on a survey of phytoplankton and algal toxins in Nigerian coastal waters. Seawater samples were obtained from four sites for phytoplankton identification, on three occasions between the middle of October 2014 and the end of February 2015 (Bar Beach and Lekki in Lagos State, Port Harcourt in Rivers State and Uyo in Akwa Ibom State). The phytoplankton community was generally dominated by diatoms and cyanobacteria; however several species of dinoflagellates were also identified: Dinophysis caudata, Lingulodinium polyedrum and two benthic species of Prorocentrum. Passive samplers (containing Diaion(®) HP-20 resin) were deployed for several 1-week periods on the same four sites to obtain profiles of algal toxins present in the seawater. Quantifiable amounts of okadaic acid (OA) and pectenotoxin 2 (PTX2), as well as traces of dinophysistoxin 1 (DTX1) were detected at several sites. Highest concentrations (60 ng OA g(-1) HP-20 resin) were found at Lekki and Bar Beach stations, which also had the highest salinities. Non-targeted analysis using full-scan high resolution mass spectrometry showed that algal metabolites differed from site to site and for different sampling occasions. Screening against a marine natural products database indicated the potential presence of cyanobacterial compounds in the water column, which was also consistent with phytoplankton analysis. During this study, the occurrence of the marine dinoflagellate toxins OA and PTX2 has been demonstrated in coastal waters of Nigeria, despite unfavourable environmental conditions, with regards to the low salinities measured. Hence shellfish samples should be monitored in future to assess the risk for public health through accumulation of such toxins in seafood.

No abstract

No abstract