The story begins with the plastisphere, the term coined for the communities of bacteria, algae, fungi, and other microbes that rapidly form biofilms on plastic debris once it enters aquatic environments. Diatoms are consistently among the earliest and most successful colonizers of these artificial surfaces. Because plastics are buoyant, long-lived, and chemically inert compared with natural substrates, they offer diatoms a novel and stable ecological niche in the sunlit surface ocean. Field surveys from the Black Sea to intertidal habitats worldwide, along with laboratory mesocosm experiments, have repeatedly documented genera such as Chaetoceros, Thalassiosira, Skeletonema, Navicula, and Nitzschia dominating plastic-associated biofilms, sometimes outcompeting every other photosynthetic organism on the particle.

What makes this dominance ecologically significant is that many of these same diatom genera are well known as producers of oxylipins, a family of lipid-derived defensive chemicals. When diatom cells are damaged, for example when a copepod crunches them during feeding, enzymes called lipoxygenases are released and convert membrane fatty acids into a diverse array of oxylipins, including polyunsaturated aldehydes and linear oxygenated fatty acids. Decades of laboratory and field research have shown that these compounds are teratogenic to copepods: they reduce egg production, impair hatching success, and can kill nauplii outright, sometimes with devastating effects on entire cohorts. In extreme cases documented in the literature, diets rich in oxylipin-producing diatoms such as Skeletonema marinoi have led to one hundred percent naupliar mortality.

Copepods, meanwhile, occupy a pivotal position in ocean ecology. With roughly thirteen thousand described species, they can make up seventy to ninety percent of mesozooplankton abundance in many regions, forming the critical link between phytoplankton and commercially important fish, marine invertebrates, and even cetaceans. They also play a major role in the ocean carbon cycle, packing organic material into dense fecal pellets that sink rapidly and transporting carbon through their daily vertical migrations. Because copepods passively entrain particles of suitable size into their feeding currents, they readily ingest microplastics that overlap in dimensions with their natural prey such as diatoms, dinoflagellates, and ciliates.

The consequences of this ingestion are well documented. Laboratory studies have shown that exposure to microplastic concentrations as low as fifty particles per milliliter can alter copepod feeding behavior, prey selection, reproductive output, molting cycles, and lipid production. In the copepod Acartia tonsa, polystyrene beads administered during egg formation produced smaller eggs, reduced naupliar survival, and population models projecting a thirty-fold decline over twenty generations. Molecular analyses reveal that microplastic ingestion triggers oxidative stress pathways involving MAPK and Nrf2 signaling, drains cellular energy reserves, and compromises swimming performance. Fecal pellets produced by exposed copepods become smaller and sink more slowly, potentially weakening the biological pump that carries carbon to the deep ocean.

The striking observation at the heart of the new review is that these microplastic effects closely resemble those historically attributed to oxylipin-producing diatoms. Reduced egg viability, impaired hatching, naupliar mortality, and disrupted maternal investment appear in both bodies of literature. Donnarumma and Russo propose that the overlap may not be coincidental. When a copepod ingests a plastic particle densely colonized by diatoms, the mechanical crushing of those cells during digestion could liberate lipoxygenases that then react with polyunsaturated fatty acids from any of the other organisms in the gut, whether eukaryotic or prokaryotic, generating oxylipins on the spot. In effect, the plastic particle would function as a chemical weapon factory inside the grazer.

Biofouling makes this scenario more plausible rather than less. Experiments consistently show that copepods ingest aged, biofilm-coated microplastics more readily than pristine particles, apparently because microbial colonization makes the plastic smell and behave more like food. Biofilm-derived infochemicals can even act as foraging cues that attract grazers. Meanwhile, nutrient limitation, a condition that increases oxylipin production in diatoms, also drives diatoms to over-secrete adhesive extracellular polymeric substances, making their biofilms stickier and more robust on plastic surfaces. The result is a particle that is simultaneously more attractive to copepods and more chemically loaded with potential toxin producers.

The authors are careful to stress that no study has yet directly demonstrated oxylipin synthesis by epiplastic diatoms on plastic debris. Their framework remains a hypothesis, albeit one grounded in converging lines of indirect evidence. To test it, they propose a clear experimental roadmap: culture an oxylipin-producing species such as Skeletonema marinoi on plastic debris, extract and characterize the resulting metabolites using liquid chromatography with tandem mass spectrometry, and compare copepod responses to sterile versus diatom-colonized particles. Adult females would be exposed to four treatments, healthy diets, free-living diatoms, sterile microplastics, and colonized microplastics, with hatching success and gene expression serving as key endpoints. Field surveys using fine neuston nets, rather than the standard manta nets that miss the relevant size fractions, would then establish whether the mechanism operates in nature.

The stakes extend well beyond copepod physiology. If plastic-borne oxylipins compound the reproductive failures already observed in laboratory studies, population-level consequences could ripple upward through marine food webs, reducing prey availability for fish larvae and other consumers. Disruption of copepod-mediated carbon export could further alter the efficiency of the biological pump, with implications for climate-relevant biogeochemical cycles. The authors also highlight a glaring geographic bias in existing research toward the Northern Hemisphere, leaving the Southern Ocean and much of the tropics as data deserts in which the combined stress of microplastics and epiplastic chemistry remains entirely unquantified.

For now, the review reframes microplastic pollution as a dual threat: a physical and nutritional burden on grazers, and a potential vector for chemical stress generated by the living communities that plastics carry with them. Whether that second threat is real in the ocean will depend on the experimental and field campaigns the authors now call for, but the convergence of evidence they assemble makes the hypothesis one of the most intriguing new directions in marine chemical ecology.

Subject of Research: Microplastics as potential vectors of diatom-derived oxylipins affecting copepod physiology and reproduction

Article Title: Microplastics as potential vectors of diatom oxylipins and possible effects on copepods

Article References: Donnarumma, V., & Russo, E. (2026). Microplastics as potential vectors of diatom oxylipins and possible effects on copepods. Discover Ecology, 2(1), Article 11. https://doi.org/10.1007/s44396-026-00029-w

Image Credits: AI Generated

DOI: 10.1007/s44396-026-00029-w

Keywords: microplastics, plastisphere, diatoms, oxylipins, copepods, marine chemical ecology, biofilms, copepod reproduction, biological pump, marine pollution, Skeletonema marinoi, zooplankton

The question matters because plankton death is not simply an endpoint. When plankton cells die, their decomposing remains release dissolved organic carbon into the surrounding seawater, a form of carbon that microbes can transform and that can be stored in the ocean for thousands of years. The fate of this carbon shapes everything from microbial food webs to the ocean’s long-term capacity to sequester greenhouse gases. Understanding the mechanisms behind plankton mortality is therefore essential for reconstructing how marine ecosystems function and how material flows through them. The trouble is that a single plankton community can consist of hundreds of coexisting species, and pinpointing how many cells within such a crowded assemblage are dying, and at what rate, has long eluded researchers.

A team at Kyoto University has now tackled this challenge by focusing on one of the most pervasive causes of plankton death: viral infection. Viruses are extraordinarily abundant in seawater, and when they infect a plankton cell they often trigger cell lysis, the process by which the cell’s membrane breaks down and its contents, including genetic material, spill into the environment. This invisible death releases ribosomal RNA, or rRNA, into the water. Rather than trying to count dying cells directly, the researchers reasoned that they could measure the RNA these cells leave behind, turning the genetic debris of viral lysis into a quantitative signal of mortality.

To build such a measurement, the team first grew laboratory cultures of two phytoplankton groups, diatoms and raphidophytes, in a seawater-based medium. They then extracted the rRNA present in the medium and quantified it using digital PCR, a highly sensitive technique capable of counting individual nucleic acid molecules. The approach faced a fundamental obstacle, however: rRNA released into seawater does not persist. It degrades over time, meaning that any measured concentration reflects both the ongoing production of cell-free rRNA and its simultaneous disappearance. Without accounting for degradation, the method would systematically underestimate how much RNA dying cells actually release.

The researchers solved this problem with an elegant trick borrowed from analytical chemistry. They introduced a culture of spike-in ribosomes, a known quantity of ribosomal material that was not produced by the plankton, into the medium and tracked how quickly it degraded. This gave them a degradation rate constant specific to their experimental conditions. They then built a flux model that incorporated both the measured changes in host cell-free rRNA over time and this degradation constant. With both terms in hand, the model could correct for the RNA that had already broken down, making it possible to estimate the true rate of cell lysis at any given moment in the experiment.

The results were striking. Viral infection enhanced the rate of cell-free rRNA production approximately 46-fold compared with uninfected cultures, and subsequent cell lysis boosted it roughly 302-fold. In the non-infected solutions, only very small amounts of rRNA were actively released by living cells, underscoring how strongly lysis signals stand out from the background noise of a healthy population. The method effectively turns viral mortality into a measurable molecular beacon, one that can be detected while the deaths themselves are happening.

Perhaps the most surprising finding emerged from the timing. In the diatom experiment, dissolved rRNA production peaked before the population density began to decline as a result of viral infection. In other words, active cell lysis was already underway while the population as a whole was still growing steadily. From a biogeochemical perspective, this implies that the supply of dissolved organic matter to the environment through cell death may occur primarily during the growth phase of a bloom, rather than during its apparent decline, as conventional observations would suggest. Cells are dying and leaking their contents into the water long before anyone watching the population curve would notice.

We did not expect the temporal decoupling between population declines and cell lysis, says corresponding author Hisashi Endo of Kyoto University. Observing the dynamics of living cells is not enough to evaluate the dissolved organic carbon that phytoplankton contribute to marine environments. The statement carries significant weight for oceanographers who model carbon cycling, because it suggests that mortality-driven carbon fluxes may be systematically misattributed in time if they are inferred solely from changes in cell abundance. Carbon could be flowing into microbial food webs and the deep ocean at moments when blooms appear to be thriving.

The methods developed by the Kyoto team for quantifying this invisible death of plankton offer a valuable new lens for understanding material flows within ecosystems. The researchers are careful to note the study’s limits. The reasons for plankton mortality are diverse, spanning grazing, nutrient starvation, disease and viral attack, and this study did not distinguish between different causes of cell lysis. The flux model detects death, but not its perpetrator. The team now intends to develop approaches that can track both the impacts and the causes of cell lysis at the species level, a step that would allow ecologists to attribute carbon release to specific pathogens and specific hosts within complex natural communities.

For Endo, the work is the continuation of a long-standing fascination with the viral dark matter of the sea. Since we revealed that a wide variety of viruses are present in seawater, I have been interested in understanding their impact on the ecosystem, he says. Using this research as a starting point, I hope to shed light on the true nature of the plankton ecosystem. As the technique matures and moves from laboratory cultures toward field applications, it could transform how scientists monitor ocean health, refine global carbon models, and appreciate the ceaseless, mostly invisible cycle of life and death playing out in every drop of seawater.

Subject of Research: Quantifying viral cell lysis of marine plankton using extracellular ribosomal RNA

Article Title: Dead or alive, plankton support marine ecosystems

Article References: Dead or alive, plankton support marine ecosystems. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: plankton, viral lysis, phytoplankton, rRNA, digital PCR, dissolved organic carbon, marine ecosystems, biogeochemical cycles, diatoms, raphidophytes, carbon sequestration, ocean viruses

New research from Flinders University in South Australia adds a sobering detail to the growing body of evidence on how a changing ocean chemistry could weaken this biological foundation. A study published in the journal Marine Ecology set out to test, with unusually high sensitivity, how common species of marine diatoms respond to one of the defining stressors of the modern ocean: acidification caused by the absorption of excess carbon dioxide from the atmosphere. The findings suggest that shifts in ocean pH can alter the growth, abundance and elemental composition of these algae, with potential downstream effects that include disruption of marine food webs, reduced export of carbon and silicon to the deep ocean, and heightened microbial and nutrient activity in surface waters.

The senior author of the study, Professor Sophie Leterme, director of the ARC Industry Transformation Training Centre for Biofilm Research and Innovation at Flinders University’s College of Science and Engineering, emphasizes that the stakes extend well beyond the algae themselves. According to Leterme, changes in seawater pH can affect how diatoms grow and what elements they accumulate, and understanding how these shifts interact across various trace elements is essential for anticipating broader ecological impacts. Her team’s work points to a chain of consequences: altered trace metal uptake in diatoms could cascade through the organisms that graze on them, through the fisheries that depend on those grazers, and through the biological carbon pump that quietly transports carbon from the sunlit surface ocean into the abyss.

The chemistry at the heart of the problem is straightforward but relentless. As humanity emits carbon dioxide, a large fraction of it dissolves into seawater, forming carbonic acid and lowering the ocean’s pH. Since the end of the Industrial Revolution, this process has already driven a global decline in surface ocean pH of approximately 0.1 units. That figure may sound modest, but because the pH scale is logarithmic, it represents an increase in acidity of roughly 30 percent. Projections suggest the decline will not stop there: by the end of this century, ocean pH is expected to fall by a further 0.3 to 0.6 units, a rate of chemical change that marine organisms have never encountered in such a short span of evolutionary time.

For diatoms, the changing acidity matters largely because of trace metals. Elements such as iron, zinc and cadmium are absorbed from seawater and play essential roles in the algae’s metabolism, including the acquisition of inorganic carbon for photosynthesis. When pH shifts, the chemical speciation of these metals in seawater changes too, altering how readily they bind to cell surfaces and how effectively diatoms can take them up. Because trace metal availability constrains the growth of phytoplankton across vast stretches of the ocean, any systematic change in metal uptake driven by acidification could reshape which algae thrive and which falter, and by extension how much carbon dioxide the ocean’s microscopic forests continue to draw down.

To test these effects directly, the Flinders researchers turned to a powerful analytical technique. Using seawater samples collected from Gulf St Vincent in South Australia and from the CSIRO algae collection, the team ran experiments on two well-studied diatom species, Thalassiosira pseudonana and Nitzschia navis-varingica. Their method of choice, neutron activation analysis, offered by far higher sensitivity than conventional approaches, allowing the researchers to quantify how much of a range of trace elements the algae absorbed under different chemical conditions. The work was supported by expertise from ANSTO, Australia’s nuclear science organization, whose facilities underpin this kind of high-precision elemental measurement.

The experimental results demonstrated that trace metal uptake by marine diatoms responds measurably to the conditions the researchers created, and the team suggests that this approach could be extended to probe how other marine organisms absorb a wide range of elements in their environments. That versatility matters, because the same ocean chemistry that changes diatom physiology also affects bacteria, zooplankton, larvae and every other layer of the marine ecosystem. A method that can precisely track elemental transfer at the base of the food web gives scientists a sharper tool for tracing how chemical stress propagates upward through the ecosystem and downward into the carbon cycle.

Diatoms also serve a second, more practical role in this research: they are excellent bio-indicators. Because their shells and their physiological responses are sensitive to water chemistry, diatoms have long been used to assess water quality in rivers, lakes and coastal seas. The new work extends that utility into the era of ocean acidification and rising water temperatures, offering a way to monitor how ongoing environmental change degrades the physiology and functioning of organisms that sit at the base of nearly every marine food chain. In effect, the same organisms that anchor ocean food webs and carbon storage also double as living gauges of ocean health, and the readings they now display are increasingly urgent.

One of the study’s most thought-provoking implications concerns a subtle tension at the heart of the ocean carbon story. In principle, higher diatom abundance and faster growth could help reduce atmospheric carbon dioxide levels by fixing more carbon near the surface. Yet the impact of lower concentrations of major and trace elements in a more acidic ocean is not well understood, and it could constrain the very growth that would make such a carbon drawdown possible. In other words, a warmer, more acidic ocean might simultaneously encourage and undermine the biological machinery of carbon export, and the balance between those forces will determine how much carbon the deep ocean ultimately stores. Resolving that uncertainty, the researchers argue, requires a better understanding of the complex processes at work in seawater.

The Flinders team also sees practical dividends beyond climate science. Insights into how marine organisms interact with surfaces and trace elements in seawater are already informing the development of novel biofilms designed to reduce shipping pollution in harbours, linking fundamental ocean chemistry research to tangible environmental applications. Together, the studies underscore a broader message: understanding the invisible chemistry of the ocean is not an academic luxury but a prerequisite for protecting both marine life and one of humanity’s most valuable natural carbon stores. As carbon emissions continue to acidify the seas, the fate of organisms barely visible to the naked eye may help decide how much of that carbon stays buried in the deep and how much returns to the air above.

The choice of study species reflects the breadth of the question. Thalassiosira pseudonana is a coastal centric diatom whose genome has been fully sequenced, making it a standard model for probing how these algae manage silica, carbon and nutrient uptake at the molecular level. Nitzschia navis-varingica, by contrast, is notable for its tolerance of variable salinity and its capacity to accumulate unusual elements, giving the researchers a useful contrast in how different diatom lineages handle metal sorption. Comparing responses across species with different ecological strategies helps distinguish effects that are general to diatoms as a group from those tied to particular life histories.

The reliance on neutron activation analysis is also significant for the field. Traditional measurements of trace metal uptake in phytoplankton often struggle with contamination, because the concentrations involved are vanishingly small and seawater itself carries background levels of many elements. Neutron activation, which detects elements by bombarding samples with neutrons and reading the characteristic radiation emitted, sidesteps many of these limitations and can quantify dozens of elements simultaneously from a single sample. That breadth matters because trace metals rarely act in isolation; iron, zinc, cadmium and other elements compete for binding sites on cell surfaces, and acidification can shift those competitive balances in ways that single-element studies would miss.

The study also connects to a longer scientific lineage. Diatoms build their intricate shells from dissolved silicon, and the coupling of silicon and carbon export is a cornerstone of how the biological pump has operated over geological timescales. If acidification weakens that coupling, the composition and sinking speed of organic material reaching the seafloor could change, altering not only carbon storage but also the food supply for deep-sea communities adapted to a steady rain of particles from above. The researchers suggest that follow-up work examining how pH-driven changes in elemental composition propagate through grazers and decomposers will be needed to close that loop, and that the experimental framework developed here can be adapted to test other organisms and other elements under future ocean conditions.

Subject of Research: How ocean acidification affects trace metal uptake by marine diatoms and its implications for ocean health and carbon sequestration.

Article Title: Sinking feeling: Testing for ocean health and carbon storage

Article References: Sinking feeling: Testing for ocean health and carbon storage. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: ocean acidification, diatoms, trace metals, carbon sequestration, marine food webs, phytoplankton, seawater pH, neutron activation analysis, Flinders University, carbon cycling, microalgae, ocean health

Lake Manzala occupies the northeastern corner of the Nile Delta, stretching roughly 60 kilometers along the Mediterranean coast between the Suez Canal and the Damietta branch of the Nile, with an average depth of just 1.15 meters. For decades the lake received nearly 98 percent of its annual inflow from six major drains, most notably Bahr El-Baqar, carrying agricultural runoff, sewage, and industrial effluent. Yet recent national restoration projects between 2017 and 2022 have focused on re-opening the narrow marine inlets, called Boughaz, that connect the lake to the Mediterranean. Dredging of these channels has increased tidal flushing, shifting salinity profiles and creating a striking north-south gradient: the northern sites experience relatively higher salinity and lower nutrient concentrations, while the southern sectors remain fresh, fertilizer-laden, and contaminated with toxic elements.

The study team, Mohamed Deyab and Fatma Ward, sampled six representative locations: Towall Ibrahim, El Nafft, Abo El-Ross, El-Deiba, Shatta, and El-Rattama. Physicochemical measurements revealed that most sites maintain a slightly alkaline pH, with values ranging from 7.6 in autumn at Towall Ibrahim to 8.5 in summer at El-Deiba. Temperature peaked at 30.1 degrees Celsius in summer at Towall Ibrahim and dropped to 14.5 degrees in winter at Abo El-Ross. Salinity emerged as the defining variable separating the sites. El-Deiba, the primary connection point between the lake and the Mediterranean, recorded the highest salinity in every season, ranging from 24.5 to 31.5 parts per thousand, indicating near-marine conditions. By contrast, Towall Ibrahim, Shatta, and Abo El-Ross showed salinity as low as 2.2 parts per thousand, reflecting their dependence on freshwater drainage.

Nutrient data told a more troubling story. Towall Ibrahim recorded the highest total nitrogen, up to 7.2 milligrams per liter, and total phosphorus, up to 1.50 milligrams per liter, during summer, while El-Deiba consistently reported the lowest concentrations of both. Dissolved oxygen followed a predictable seasonal pattern, reaching winter maxima between 6.5 and 9.4 milligrams per liter and falling to summer minima as low as 2.8 milligrams per liter, since colder water holds more dissolved gas. The contrast between sites was stark: high oxygen near the marine-flushed El-Deiba, chronically low oxygen at Towall Ibrahim and Abo El-Ross, where decomposition of organic matter from drainage water depletes the supply. When the researchers calculated the Water Quality Index, El-Deiba emerged as the best site with values between 22 and 45, while Towall Ibrahim was the most degraded, averaging 154.2. All sites showed their worst water quality in summer and their best in winter.

Carlson’s Trophic Status Index, computed from chlorophyll-a and total phosphorus, confirmed that the northern lake is highly eutrophic at most sites. The highest value, 94.5, was recorded in summer at Towall Ibrahim, coinciding with a chlorophyll-a concentration of 140 micrograms per liter, placing the site firmly in the hypereutrophic category. Even the lowest value, 64.08, recorded in winter at El-Deiba, falls within the eutrophic range, suggesting the lake sits perilously close to hypereutrophic conditions despite marine flushing. The authors note that calculating the index from chlorophyll and phosphorus rather than water transparency avoids the inaccuracies that arise in shallow, turbid systems where suspended sediments, not algae, often control light penetration.

Against this chemical backdrop, the phytoplankton community told its own seasonal story. The team identified 32 species across four phyla: 17 bacillariophytes, or diatoms; 10 cyanophytes, or blue-green bacteria; 4 dinophytes; and a single xanthophyte. Diatoms contributed the greatest number of species, but cyanobacteria dominated in sheer cell numbers and biomass throughout most of the year. The tiny picocyanobacterium Synechocystis salina proved to be the most abundant organism year-round, peaking in spring with 156.9 million cells per liter at El-Rattama and a biomass of 12.589 milligrams per liter. Seasonal species counts collapsed in summer, when only 7 species were recorded, compared with 21 in autumn, 12 in spring, and just 4 in winter. Diatoms reached their own maximum in autumn, hitting 4.58 million cells per liter and 2.313 milligrams per liter of biomass at El-Rattama, while dinoflagellates peaked at 38.09 million cells per liter in autumn and 10.78 milligrams per liter of biomass in winter at the same site.

The autumn diatom bloom, the authors explain, is a classic temperate-lake mechanism playing out in a delta lagoon. During hot months, the shallow water column can become weakly stratified by temperature. As air temperatures drop in autumn, surface water cools, densifies, and sinks, creating vertical mixing that hauls nutrient-rich sediments and dissolved silica from the lake bottom up into the sunlit zone where diatoms live. Diatoms, which build their glassy frustules from silica, also prefer cooler conditions than the brutal heat of an Egyptian summer. The dominance of Nitzschia at only a single autumn station in this study contrasted with earlier surveys that found the genus across the entire lake, a discrepancy the researchers attribute to shifts in nutrient loading and organic discharge between study periods, as well as competitive exclusion by seasonally dominant cyanobacteria at other stations.

The prevalence of Synechocystis salina carries ecological consequences that ripple up the food web. This organism is a supremely adaptable competitor, capable of re-tuning its photosynthetic pigment antenna in response to changing light, and previous work has documented its tolerance of heavy metals and its capacity to strip organic load from wastewater, traits that help it thrive in polluted, saline conditions. But dominance by such small cyanobacteria creates what the authors call a trophic bottleneck: energy becomes trapped at the base of the food web in cells of poor nutritional quality for zooplankton, potentially suppressing the small fish populations that larger commercial species depend upon. This matters enormously in a lake that has averaged roughly 64 thousand tonnes of annual fish landings over the past decade, with cichlid tilapia making up about 70 percent of the catch. Licensed fishing activity on the lake has already collapsed dramatically, from 2,748 boats and 2,711 fishermen in 2021 to just 485 boats and 1,016 fishermen in 2022.

Diversity metrics revealed a clear seasonal signature. The Shannon-Wiener diversity index and species richness peaked in autumn at nearly every site except Shatta, which remained at persistently low diversity, with index values between 0.11 and 0.24. Abo El-Ross swung from a single genus in winter to the most diverse site in autumn, reaching an index of 1.47. Statistical analysis showed that species richness correlated significantly and positively with temperature and dissolved oxygen, but significantly and negatively with pH, total nitrogen, total phosphorus, and chlorophyll-a. Salinity showed a moderate positive correlation with species richness and negative correlations with nutrients and chlorophyll. Total nitrogen and total phosphorus were almost perfectly correlated with each other and with chlorophyll-a, confirming that nutrient loading is the primary engine of algal biomass in the lake. Two-way ANOVA demonstrated that both site and season significantly shaped cell numbers and biomass, with season exerting the stronger effect.

The broader message is unambiguous: despite restoration efforts that have reconnected the lake to the sea, the northern side of Lake Manzala remains under severe environmental stress, particularly at Towall Ibrahim and Abo El-Ross, where nutrient concentrations fuel summer algal blooms and depress oxygen. The relative health of El-Deiba demonstrates that enhanced marine exchange can dilute pollutants and support a more diverse, marine-influenced community, offering a template for future management. The authors conclude that phytoplankton in the lake respond directly to shifts in temperature, salinity, and nutrient availability, and they call for intensified restoration efforts alongside further research into the competitive interactions among phytoplankton species. For a lake that feeds millions of Egyptians with inexpensive fish, the microscopic community at its base may be the most important early warning system the country has.

Subject of Research: Seasonal dynamics of phytoplankton communities and water quality in the northern side of Lake Manzala, Egypt

Article Title: Seasonal variations in phytoplanktonic community structure at the northern side of Lake Manzala, Egypt

Article References: Deyab, M., & Ward, F. (2026). Seasonal variations in phytoplanktonic community structure at the northern side of Lake Manzala, Egypt. Discover Ecology, 2(1), Article 17. https://doi.org/10.1007/s44396-026-00035-y

Image Credits: AI Generated

DOI: 10.1007/s44396-026-00035-y

Keywords: Lake Manzala, phytoplankton, cyanobacteria, eutrophication, water quality, Mediterranean, Egypt, Synechocystis salina, diatoms, nutrient pollution, biodiversity, fisheries