Noctiluca scintillans: Dynamics, Size Measurements and Relationships With Small Soft-Bodied Plankton in the Belgian Part of the North Sea

Abstract

Climate driven changes and anthropogenic pressures on the marine environment have been shown to favor the increase in certain potentially harmful species. Among them, Noctiluca scintillans, a common dinoflagellate, often blooms during warm summers and is known to affect plankton communities. In this study, we assessed the dynamics in abundance and cell size of N. scintillans as well as the relationship between N. scintillans and small soft-bodied zooplankton in the Belgian part of the North Sea (BPNS), since negative correlations between these plankton groups have been previously reported for nearby regions. This study is the first to present consistently counted N. scintillans cell numbers and measured cell lengths, through the analysis of ZooScan images from samples taken monthly at stations throughout the coastal zone of the BPNS. The results show that N. scintillans demonstrated clear seasonal dynamics with both high densities and large cell sizes in spring/summer (May-July). The occurrence of N. scintillans in the analyzed plankton samples and the abundance of N. scintillans at the observed peak intensities nearly tripled over a period of 5 years. A zero-inflated model showed a correlation of N. scintillans abundance with temperature as well as with phosphate concentrations, suggesting that anthropogenic influences such as climate change and riverine nutrient inputs could affect the temporal dynamics of the species. The results, on the other hand, did not show any negative impact of N. scintillans on the soft-bodied plankton community.

Modeling Dynamic Processes in the Black Sea Pelagic Habitat—Causal Connections between Abiotic and Biotic Factors in Two Climate Change Scenarios

“…The phenomenon causes mortality among fish, many of which are of economic importance, as well as marine invertebrates, due to the accumulation of high ammonia levels in the water [85]. N. scintillans plays an essential role in marine food chains [84], feeding on a wide variety of organisms such as phytoplankton (mainly diatoms), eggs, larvae, and fecal pellets of crustaceans, as well as other mesozooplanktonic organisms [86]. High densities of this dinoflagellate can limit the local population growth of copepods, not only when they compete for food but also because they feed on their eggs and nauplii [87].…”

Seasonal Metabolic Dynamics of Microeukaryotic Plankton: A Year-long Metatranscriptomic Study in a Temperate Sea

“…The observed seasonal shifts in taxonomic assignments of gene transcripts echo well- documented phenological patterns in the Southern Bight. These include the early spring bloom of Phaeocystis globosa 36 , the prevalence of Noctiluca scintillans between May and July 37 , and the late summer bloom of the invasive ctenophore Mnemiopsis leidyi 38 . These phenological patterns are intricately linked to the seasonal oscillations of abiotic factors such as temperature, nutrient availability, or solar irradiance.…”

Interannual Variation in the Zooplankton Community of the North Adriatic Sea under Short-Term Climatic Anomalies

“…Our results confirmed the influence of primary productivity on Noctiluca cell concentration, which reached its peak in the northern sub-area, directly influenced by the Po River discharge in which low salinity values can increase water stratification in summer, while nutrient input from land fuels the formation of phytoplanktonic blooms [33,46,47]. The disappearance of Noctiluca in 2022 might be related to the concurrent increase in some cladoceran and copepod species, which might have been negatively affected by food competition and direct predation from this dinoflagellate [61,[65][66][67]. Indeed, even if no significant correlation was found for copepods or cladocerans with dinoflagellates, we did notice a low presence of both taxa in the sample where Noctiluca abundance was higher.…”

“…The ecological effect that the zooplankton shift registered in June 2022 might have had is hard to predict, as many major components of the plankton community decreased, while others increased. The presence of large quantities of Noctiluca scintillans could definitely have negative effects on other zooplankters [61,[65][66][67], but it might also be favorable for those organisms that can prey on the protist. Studying the connection between athecate dinoflagellates and higher trophic levels is not as easy as for other unicellular marine organisms because they lack hard structures that are preserved in gut contents and are readily digested [79,80].…”