Non-pollen palynomorphs as indicators of local environmental conditions in a Neotropical Estuary (Northeast Brazil)

Abstract

Non-pollen palynomorphs (NPPs) are organic-walled microfossils derived from diverse aquatic and terrestrial organisms, frequently observed in palynological studies. This study documents the distribution of NPPs in surface sediment samples from the two main rivers of Camamu Bay (Northeast Brazil), analyzed to explore their response to estuarine environmental and nutritional gradients. Using standard palynological techniques, 69 NPP taxa were identified, spanning 40 divisions, including dinoflagellates, foraminiferal linings, chlorophytes, cyanobacteria, ciliates, amoebozoans, scolecodonts, zoological fragments, and fungal spores. Assemblages were dominated by fungal spores across most stations. Distinct environmental gradients were reflected in NPP distribution, for instance upstream stations with low salinity (3 psu) and high nutrient ratios favored chlorophytes, while downstream stations with higher salinity (up to 35 psu) and lower N:P ratios (<40 μM) were dominated by foraminiferal linings. Multivariate statistic analyses revealed that salinity and nutrient stoichiometry were significant drivers of assemblage composition. These findings highlight the utility of NPPs as indicators of environmental and biogeochemical conditions, particularly in low-latitude estuarine systems, and underscore their potential applications in paleoecological reconstruction.