Phytoplankton and Bacterial Communities’ Patterns in a Highly Dynamic Ecosystem (Central Mediterranean Sea)

Abstract

The Straits of Messina (Southern Italy, Mediterranean Sea) are a very complex area: they connect two basins (Tyrrhenian and Ionian) with different hydrographic features and is characterised by upwelling and mixing phenomena. The aim of the study was to evaluate if and how the physical and chemical water conditions and hydrodynamics influenced the phytoplankton and bacterial patterns and the functioning of this ecosystem. During a late winter survey, size-fractionated phytoplankton (from 0.2 to 200 μm) biomass (chlorophyll a), cell densities and species composition as well as total picoplankton abundances, morphotype composition, and activity levels of the enzymes leucine aminopeptidase, β-glucosidase, and alkaline phosphatase were investigated. The obtained results showed a marked diversification among the water masses identified within the Straits area. The analyses of the phytoplankton diversity indices, particularly those based on phylogenetic relationships between species (indices of taxonomic diversity and distinctness), confirmed our findings. In conclusion, the patterns of phytoplankton and bacterial communities provide a suitable approach to evaluate how microbial communities respond to changing environmental scenarios. This tool could be applied to other temperate Mediterranean ecosystems.

Variations in bacterial community at Chlorophyll Maximum (C-Max) depths along the west coast of India due to seasonal changes in the primary productivity

“…8a). Understanding the metabolic interactions between primary producers, such as photoautotrophic species like phytoplanktons and Cyanobacteria and heterotrophic organisms, such as bacteria and archaea, is essential for understanding how ecosystems work (Caroppo et al, 2022). The results of our study indicate that upwelling has the potential to increase the metabolic capacity of the majority of the bacterial community, particularly in the areas of prokaryotic carbon fixation and various cellular catabolic processes (Fig.…”

“…The functional diversity of the bacterial assemblages is known to vary, with evidence suggesting that the upwelling seasons may exhibit higher levels of functional diversity than other periods. This indicates that during the upwelling season, the metabolism of microbial communities is particularly active in breaking down complex organic compounds such as carbohydrates, proteins and polysaccharides (Caroppo et al, 2022). However, our previous study based on culturable bacterial populations found that functional activities in the water column during the monsoon season were reduced comparatively than in the non-monsoon season (Parab et al, 2022).…”

“…Upwelling circumstances are linked to an increase in energy metabolic processes (Coelho-Souza et al, 2012; Gregoracci et al, 2015; Parvathi et al, 2019), such as prokaryotic carbon fixation, nitrogen metabolism and methane metabolism, which was also evident from our study (Fig.8a). Understanding the metabolic interactions between primary producers, such as photoautotrophic species like phytoplanktons and Cyanobacteria and heterotrophic organisms, such as bacteria and archaea, is essential for understanding how ecosystems work (Caroppo et al, 2022). The results of our study indicate that upwelling has the potential to increase the metabolic capacity of the majority of the bacterial community, particularly in the areas of prokaryotic carbon fixation and various cellular catabolic processes (Fig.…”

Picoplankton diversity in an oligotrophic and high salinity environment in the central Adriatic Sea

“…Picoplankton play a key role in the marine environment. Through their different processes (autotrophic, heterotrophic, photoheterotrophic), they are involved in the functioning of the marine environment, especially in oligotrophic areas 1 – 4 . Determining the patterns of bacterial communities provides a suitable approach to assessing their response to changes in the environment 4 .…”