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This research aimed to describe plankton diversity at rice field-pond in Glagah Village, Lamongan that can be used for fish culture. Sampling was done by purposive sampling with 5 sampling points at each end of the pond and in the middle, the place of rice field-pond around of the school. Each sampling point is divided into 2 depth variations, surface (0 cm) and base (70 cm). The results showed in the first point found 1 type of phytoplankton and 1 type of zooplankton, the second point found 9 types of phytoplankton and 2 type of zooplankton, the third point found 10 types of phytoplankton and 3 types of zooplankton, in the fourth point found 2 types of zooplankton while in the fifth point found 1 type of phytoplankton and 1 type of zooplankton. From the observation concluded that phytoplankton diversity of H '2.27 (medium) and zooplankton of H' 1.543 (medium). So it can be concluded that the diversity of phytoplankton in rice field-pond is greater than zooplankton. Physical and chemical characteristics at rice field-pond water affect the plankton diversity so that it must be maintained.

Molecular characterization of interactions between a globally distributed marine diatom and its bacterial consortium. Interactions between phytoplankton and marine bacteria Experimental difficulties mean that little is known about the interplay between phytoplankton and bacteria that provides the foundation of marine ecosystems. Here Virginia Armbrust and colleagues use a laboratory model system to characterize a bacterial consortium associated with a globally distributed diatom. They find that in consortium culture experiments Sulfitobacter sp. promote cell division in the diatom Pseudo-nitzschia multiseries through secretion of the indole-3-acetic acid (IAA), which is synthesized from both diatom-secreted and endogenous tryptophan. The authors use metabolomics and metatranscriptomics to identify IAA and some of the genes associated with IAA production in the ocean, although further work will be needed to fully investigate the ecological relevance of the pathway identified in the laboratory. This study is among the first to characterize at the molecular level the currency used to support a microbial consortium in the ocean and lays the groundwork for future efforts. Interactions between primary producers and bacteria impact the physiology of both partners, alter the chemistry of their environment, and shape ecosystem diversity 1 , 2 . In marine ecosystems, these interactions are difficult to study partly because the major photosynthetic organisms are microscopic, unicellular phytoplankton 3 . Coastal phytoplankton communities are dominated by diatoms, which generate approximately 40% of marine primary production and form the base of many marine food webs 4 . Diatoms co-occur with specific bacterial taxa 3 , but the mechanisms of potential interactions are mostly unknown. Here we tease apart a bacterial consortium associated with a globally distributed diatom and find that a Sulfitobacter species promotes diatom cell division via secretion of the hormone indole-3-acetic acid, synthesized by the bacterium using both diatom-secreted and endogenous tryptophan. Indole-3-acetic acid and tryptophan serve as signalling molecules that are part of a complex exchange of nutrients, including diatom-excreted organosulfur molecules and bacterial-excreted ammonia. The potential prevalence of this mode of signalling in the oceans is corroborated by metabolite and metatranscriptome analyses that show widespread indole-3-acetic acid production by Sulfitobacter- related bacteria, particularly in coastal environments. Our study expands on the emerging recognition that marine microbial communities are part of tightly connected networks by providing evidence that these interactions are mediated through production and exchange of infochemicals.

Traveling from the rock pools of the shoreline to the deepest depths of the ocean, a blending of illustrations and facts about marine animals provides an introduction to some of the ocean's rarely seen creatures.

Blooms of marine phytoplankton fix complex pools of dissolved organic matter (DOM) that are thought to be partitioned among hundreds of heterotrophic microbes at the base of the food web. While the relationship between microbial consumers and phytoplankton DOM is a key component of marine carbon cycling, microbial loop metabolism is largely understood from model organisms and substrates. Here, we took an untargeted approach to measure and analyze partitioning of four distinct phytoplankton-derived DOM pools among heterotrophic populations in a natural microbial community using a combination of ecogenomics, stable isotope probing (SIP), and proteomics. Each 13C-labeled exudate or lysate from a diatom or a picocyanobacterium was preferentially assimilated by different heterotrophic taxa with specialized metabolic and physiological adaptations. Bacteroidetes populations, with their unique high-molecular-weight transporters, were superior competitors for DOM derived from diatom cell lysis, rapidly increasing growth rates and ribosomal protein expression to produce new relatively high C:N biomass. Proteobacteria responses varied, with relatively low levels of assimilation by Gammaproteobacteria populations, while copiotrophic Alphaproteobacteria such as the Roseobacter clade, with their diverse array of ABC- and TRAP-type transporters to scavenge monomers and nitrogen-rich metabolites, accounted for nearly all cyanobacteria exudate assimilation and produced new relatively low C:N biomass. Carbon assimilation rates calculated from SIP data show that exudate and lysate from two common marine phytoplankton are being used by taxonomically distinct sets of heterotrophic populations with unique metabolic adaptations, providing a deeper mechanistic understanding of consumer succession and carbon use during marine bloom events.

The ability to predict microbial community dynamics lags behind the quantity of data available in these systems. Most predictive models use only environmental parameters, although a long history of ecological literature suggests that community complexity should also be an informative parameter. Thus, we hypothesize that incorporating information about a community’s complexity might improve predictive power in microbial models. Here, we present a new metric, called community ‘cohesion,’ that quantifies the degree of connectivity of a microbial community. We analyze six long-term (10+ years) microbial data sets using the cohesion metrics and validate our approach using data sets where absolute abundances of taxa are available. As a case study of our metrics’ utility, we show that community cohesion is a strong predictor of Bray–Curtis dissimilarity ( R 2 =0.47) between phytoplankton communities in Lake Mendota, WI, USA. Our cohesion metrics outperform a model built using all available environmental data collected during a long-term sampling program. The result that cohesion corresponds strongly to Bray–Curtis dissimilarity is consistent across the six long-term time series, including five phytoplankton data sets and one bacterial 16S rRNA gene sequencing data set. We explain here the calculation of our cohesion metrics and their potential uses in microbial ecology.

Unicellular eukaryotic phytoplankton, such as diatoms, rely on microbial communities for survival despite lacking specialized compartments to house microbiomes (e.g., animal gut). Microbial communities have been widely shown to benefit from diatom excretions that accumulate within the microenvironment surrounding phytoplankton cells, known as the phycosphere. However, mechanisms that enable diatoms and other unicellular eukaryotes to nurture specific microbiomes by fostering beneficial bacteria and repelling harmful ones are mostly unknown. We hypothesized that diatom exudates may tune microbial communities and employed an integrated multiomics approach using the ubiquitous diatom Asterionellopsis glacialis to reveal how it modulates its naturally associated bacteria. We show that A. glacialis reprograms its transcriptional and metabolic profiles in response to bacteria to secrete a suite of central metabolites and two unusual secondary metabolites, rosmarinic acid and azelaic acid. While central metabolites are utilized by potential bacterial symbionts and opportunists alike, rosmarinic acid promotes attachment of beneficial bacteria to the diatom and simultaneously suppresses the attachment of opportunists. Similarly, azelaic acid enhances growth of beneficial bacteriawhile simultaneously inhibiting growth of opportunistic ones.We further show that the bacterial response to azelaic acid is numerically rare but globally distributed in the world’s oceans and taxonomically restricted to a handful of bacterial genera. Our results demonstrate the innate ability of an important unicellular eukaryotic group to modulate select bacteria in their microbial consortia, similar to higher eukaryotes, using unique secondary metabolites that regulate bacterial growth and behavior inversely across different bacterial populations.

Key Points Phytoplankton are the most abundant primary producers in the oceans, and phytoplankton blooms are recognizable signs of the annual productivity cycle in aquatic systems. Phytoplankton blooms contain dense and diverse heterotrophic bacterial populations that determine the fate of much of the carbon that is fixed by these primary producers. This is achieved by the transformation of phytoplankton-derived organic matter, which returns carbon to the atmosphere as CO 2 and converts carbon to bacterial biomass, which enters the marine food web or renders it resistant to microbial degradation, such that it contributes to a vast pool of recalcitrant carbon in the ocean. Although blooms vary in terms of phytoplankton composition and environmental conditions, a limited number of bacterial taxa dominate bloom-associated microbial communities. The most frequently observed bacteria belong to the Flavobacteriia and Proteobacteria. Cultivated representatives of both flavobacteria and roseobacters are currently the main models that are used to study phytoplankton–bacteria interactions. These two lineages show substantial metabolic versatility, which seems to fuel these interactions. Culture-based studies of roseobacters suggest that they form more intimate associations with specific phytoplankton than flavobacteria. Specific physiological processes that have been identified in cultured representatives and are supported by metagenomic data from natural populations have been proposed to facilitate these interactions. These include the production of secondary metabolites, catabolism of various phytoplankton-derived low molecular weight compounds and cell surface structures that facilitate cellular adhesion. Genomic, metatranscriptomic and metaproteomic data suggest that flavobacteria are particularly well equipped to use the high molecular weight components of phytoplankton-derived material. Other flavobacterial physiologies, including cell adhesion and motility, may be important in facilitating interactions between flavobacteria and phytoplankton. Marine phytoplankton blooms are annual spring events that are accompanied by a surge in heterotrophic bacteria, primarily roseobacters, flavobacteria and members of the Gammaproteobacteria, which recycle most of the carbon that is fixed by the primary producers. In this Review, Buchan et al . describe the emerging physiological features and functions of these bacterial communities and their interactions with phytoplankton. Marine phytoplankton blooms are annual spring events that sustain active and diverse bloom-associated bacterial populations. Blooms vary considerably in terms of eukaryotic species composition and environmental conditions, but a limited number of heterotrophic bacterial lineages — primarily members of the Flavobacteriia, Alphaproteobacteria and Gammaproteobacteria — dominate these communities. In this Review, we discuss the central role that these bacteria have in transforming phytoplankton-derived organic matter and thus in biogeochemical nutrient cycling. On the basis of selected field and laboratory-based studies of flavobacteria and roseobacters, distinct metabolic strategies are emerging for these archetypal phytoplankton-associated taxa, which provide insights into the underlying mechanisms that dictate their behaviours during blooms.

Eukaryotic phytoplankton have a small global biomass but play major roles in primary production and climate. Despite improved understanding of phytoplankton diversity and evolution, we largely ignore the cellular bases of their environmental plasticity. By comparative 3D morphometric analysis across seven distant phytoplankton taxa, we observe constant volume occupancy by the main organelles and preserved volumetric ratios between plastids and mitochondria. We hypothesise that phytoplankton subcellular topology is modulated by energy-management constraints. Consistent with this, shifting the diatom Phaeodactylum from low to high light enhances photosynthesis and respiration, increases cell-volume occupancy by mitochondria and the plastid CO2-fixing pyrenoid, and boosts plastid-mitochondria contacts. Changes in organelle architectures and interactions also accompany Nannochloropsis acclimation to different trophic lifestyles, along with respiratory and photosynthetic responses. By revealing evolutionarily-conserved topologies of energy-managing organelles, and their role in phytoplankton acclimation, this work deciphers phytoplankton responses at subcellular scales.