Marine Plankton Research Articles

Past foraminiferal acclimatization capacity is limited during future warming.

Climate change affects marine organisms, causing migrations, biomass reduction and extinctions1,2. However, the abilities of marine species to adapt to these changes remain poorly constrained on both geological and anthropogenic timescales. Here we combine the fossil record and a global trait-based plankton model to study optimal temperatures of marine calcifying zooplankton (foraminifera, Rhizaria) through time. The results show that spinose foraminifera with algal symbionts acclimatized to deglacial warming at the end of the Last Glacial Maximum (LGM, 19-21 thousand years ago, ka), whereas foraminifera without symbionts (non-spinose or spinose) kept the same thermal preference and migrated polewards. However, when forcing the trait-based plankton model with rapid transient warming over the coming century (1.5 °C, 2 °C, 3 °C and 4 °C relative to pre-industrial baseline), the model suggests that the acclimatization capacities of all ecogroups are limited and insufficient to track warming rates. Therefore, foraminifera are projected to migrate polewards and reduce their global carbon biomass by 5.7-15.1% (depending on the warming) by 2100 relative to 1900-1950. Our study highlights the different challenges posed by anthropogenic and geological warming for marine plankton and their ecosystem functions.

Is in-situ burning an acceptable mitigation option after a major oil spill? Impact on marine plankton

Major oil spills can impose a significant environmental hazard on the marine ecosystem, and a promising mitigation measure is in-situ oil burning (ISB). However, our knowledge of the impact of the burned residues and soot deposition on the marine ecosystem is still limited. We investigated the effects of burned oil residue and soot deposition on the marine plankton communities of the oligotrophic Eastern Mediterranean Sea with a mesocosm experiment. Three triplicated treatments were tested: (1) Iranian crude oil was added and burned (Burned treatment); (2) soot was collected and deposited with artificial rain (Soot); and (3) a non-contaminated Control. Results revealed that Low Nucleic Acid heterotrophic bacteria, Synechococcus spp., and pigmented pico-nano Eukaryotes (pnEuk) were negatively affected in the Burned and Soot treatments. Viruses, heterotrophic pnEuk and ciliates (in Soot) were crucial for controlling the High Nucleic Acid bacteria. Ciliates and most dinoflagellates showed a negative response to the burned residues but were less affected or were even favored when exposed to soot. Our results show that ISB affected the structure and dynamics of the plankton food web through burned residues and soot depositions. However, since the effects appeared at least three days after the ignition, ISB could be combined with subsequent burned residue collection to minimize its impact on the pelagic ecosystem.

Influence of environmental parameters on marine plankton diversity in the southern coastal waters of Korea: Emphasis on thermal stratification

Plankton are fundamental to aquatic ecosystems, forming the base of the marine food web and playing a crucial role in the global carbon cycle. While the impact of environmental factors on marine plankton ecosystems has been widely studied, the seasonal variability in plankton diversity has received comparatively less attention. Here, we investigated the complexity and distribution of plankton species in Korean coastal waters in relation to seasonal environmental changes, particularly those linked to water mass characteristics and the presence of a thermocline, using alpha and beta diversity indices. A thermocline was observed at all stations in July, coinciding with the lowest diversity and richness, but was absent in September, when diversity indices peaked. In the upper layer above the thermocline, diatom species such as Pseudo-nitzschia delicatissima and Skeletonema costatum were dominant. Analysis of the Shannon index suggested that planktonic ecosystems in the South Sea of Korea from May to September 2021 were well-balanced. These findings enhance our understanding of the potential effects of environmental variability and thermal stratification on plankton biodiversity and community dynamics in Korean coastal waters.

On the possibility of yet a third kinetochore system in the protist phylum Euglenozoa.

A macromolecular assembly called the kinetochore is essential for the segregation of genetic material during eukaryotic cell division. Therefore, characterization of kinetochores across species is essential for understanding the mechanisms involved in this key process across the eukaryotic tree of life. In particular, little is known about kinetochores in divergent protists such as Euglenozoa, a group of unicellular flagellates that includes kinetoplastids, euglenids, and diplonemids, the latter being a highly diverse and abundant component of marine plankton. While kinetoplastids have an unconventional kinetochore system and euglenids have a canonical one similar to traditional model eukaryotes, preliminary searches detected neither unconventional nor canonical kinetochore components in diplonemids. Here, we employed state-of-the-art deep homology detection protocols but still could not detect orthologs for the bulk of kinetoplastid-specific nor canonical kinetochore proteins in diplonemids except for a putative centromere-specific histone H3 variant. Our results suggest that diplonemids evolved kinetochores that do not resemble previously known ones.

Radiolaria as a study system for marine plankton in a changing climate

Radiolaria as a study system for marine plankton in a changing climate

Seasonal trends in Subantarctic plankton δ13C and δ15N are driven by phytoplankton dynamics and nutrient preference

AbstractThe carbon and nitrogen isotope ratios (δ13C and δ15N) of marine plankton record biogeochemical processes at the base of the food web. In the Southern Ocean, such data, predominantly from summer, have been used to infer surface CO2 concentrations and the potential for biological carbon export. However, variability in plankton δ13C and δ15N remains poorly understood, with the lack of seasonal measurements from the Southern Ocean emerging as a particular limitation. Here, we investigate the δ13C and δ15N of suspended particulate matter (SPM) and zooplankton collected from the Subantarctic Ocean in winter, summer, and autumn. The low summertime δ13CSPM and δ15NSPM can be explained by strong diatom reliance on nitrate supplied during winter mixing. A subsequent increase in δ13CSPM and decrease in δ15NSPM by autumn is consistent with iron limitation in mid‐ to late‐summer favoring diatom succession by nano‐phytoplankton that consume mainly recycled ammonium. By winter, bacterial decomposition of biomass outpaces new biomass production, decreasing δ13CSPM and raising δ15NSPM. The δ13C and δ15N of contemporaneously sampled zooplankton generally reflect the variability in δ13CSPM and δ15NSPM, with one autumn mismatch suggesting that in situ SPM is not always the dominant zooplankton food source. Our study shows how nutrient dynamics and phytoplankton community composition shape the seasonality of the Subantarctic's isotopic baselines, emphasizing a key role for iron availability. This work has implications for isotope‐based food web studies, highlighting the need to consider seasonal variability in δ13CSPM and δ15NSPM, as well as the different turnover times of phytoplankton (i.e., SPM) vs. zooplankton biomass.

Marine plankton community and net primary production responding to island-trapped waves in a stratified oligotrophic ecosystem

The oligotrophic Adriatic Sea is characterized during a typical summer by low productivity caused by strong water column stratification, which inhibits vertical mixing and nutrient supply to the euphotic zone. These conditions can be disrupted by transient physical forcing, which enhances nutrient fluxes and creates localized hotspots of relatively high net primary production. In this study, plankton abundance and diversity were investigated in relation to the physical forcing and nutrient concentrations in an area affected by island-trapped waves (ITWs) near Lastovo Island (Adriatic Sea). The episodic ITW events resulted in enhanced uplift and vertical excursion of the thermocline, marked by anomalously higher nutrient concentrations and a corresponding increase in net primary production in the thermocline layer. Physicochemical properties explained 11.7 % (p = 0.002) of the variability in micro- and nanophytoplankton and 88.9 % (p = 0.001) in the picoplankton community. A significant response to the ITW phenomenon in the plankton community composition (p = 0.001) was observed for bacterioplankton. Among the identified amplicon sequence variances, primary producers were scarce and mainly represented cyanobacteria (Synechococcus strain CC9902), stramenopiles (Pelagomonas), and chlorophytes (Ostreococcus). The remaining amplicon sequence variances were assigned to the classes Copepoda, parasitic fungi (Meyerozyma spp.), mixotrophic dinoflagellates (family Peridiniales, mostly the genus Blastodinium), and parasitic Ciliophora (Scuticociliata). Bacterial ecological functions corresponded to chemoheterotrophic, degradation, and fermentation processes, whereas samples collected after the most intense ITW episode also showed abundant bacteria linked to microplastic degradation and parasitosis. These results highlight the ecological role of localized physical phenomena in enhancing nearshore primary productivity and fine shifts in plankton taxa in oligotrophic systems.

Significant alleviation of cadmium toxicity in Thalassiosira weissflogii through the combined effect of high silicon and zinc supplementation

Cadmium (Cd), a prevalent pollutant in near-shore seawater ecosystems, poses a significant threat to marine biota. Zinc (Zn) and Cd can have interchangeable physiological effects in marine plankton, and both can influence the synthesis of siliceous walls. Consequently, the concentrations of zinc and silicon may jointly impact the toxicity of Cd. This study endeavors to elucidate the combined effect of silicon (Si) and zinc (Zn) on the growth and physiological responses of the marine diatom species Thalassiosira weissflogii when subjected to Cd-induced stress conditions (190.7 μg L−1). Our results reveal statistically improvements (p<0.05) in biomass production, reductions (p<0.05) in superoxide dismutase (SOD) activity and extracellular secretion in T. weissflogii when high concentrations of Si (172 µmol L−1) and Zn (18.3 nmol L−1) were applied simultaneously. Additionally, examination of Cd bioconcentration factors (BCF) derived from Cd uptake kinetics and intracellular Cd content measurements underscores the ability of elevated Si and Zn concentrations to reduce intracellular Cd accumulation (p<0.05). The ability of Si and Zn to mitigate Cd toxicity was further evidenced by increased cellular biosilica content and maintenance of cell morphology, suggesting a protective role in preserving structural integrity and growth. Our findings underscore the synergistic benefits of Si and Zn in enhancing the resilience of T. weissflogii to Cd stress, providing valuable insights into the potential use of nutrient amendments as a strategy for mitigating heavy metal contamination in marine environments.

Taxonomic and abundance biases affect the record of marine eukaryotic plankton communities in sediment DNA archives.

Environmental DNA (eDNA) preserved in marine sediments is increasingly being used to study past ecosystems. However, little is known about how accurately marine biodiversity is recorded in sediment eDNA archives, especially planktonic taxa. Here, we address this question by comparing eukaryotic diversity in 273 eDNA samples from three water depths and the surface sediments of 24 stations in the Nordic Seas. Analysis of 18S-V9 metabarcoding data reveals distinct eukaryotic assemblages between water and sediment eDNA. Only 40% of Amplicon Sequence Variants (ASVs) detected in water were also found in sediment eDNA. Remarkably, the ASVs shared between water and sediment accounted for 80% of total sequence reads suggesting that a large amount of plankton DNA is transported to the seafloor, predominantly from abundant phytoplankton taxa. However, not all plankton taxa were equally archived on the seafloor. The plankton DNA deposited in the sediments was dominated by diatoms and showed an underrepresentation of certain nano- and picoplankton taxa (Picozoa or Prymnesiophyceae). Our study offers the first insights into the patterns of plankton diversity recorded in sediment in relation to seasonality and spatial variability of environmental conditions in the Nordic Seas. Our results suggest that the genetic composition and structure of the plankton community vary considerably throughout the water column and differ from what accumulates in the sediment. Hence, the interpretation of sedimentary eDNA archives should take into account potential taxonomic and abundance biases when reconstructing past changes in marine biodiversity.

Long-term monitoring dataset of plankton assemblages in western Taiwan coastal water

Plankton plays important roles in the marine ecosystems as important producers for primary production, major components in the global biogeochemical cycles, and the foundation of the marine food web. Despite their importance, long-term monitoring data about marine plankton are fairly limited, especially in the Asia-Pacific region. We fill this knowledge gap by providing a 29-year long-term monitoring data on the coastal areas of western Taiwan quarterly from 1993 to 2021. This long-term monitoring data can be used to set proper baseline for detecting human-induced impacts on the plankton, as well as modelling future scenarios under global changes.

Ballast water transport of alien phytoplankton species to the brazilian amazon coast

The aim of this study was to investigate the presence of alien phytoplankton species transported through ballast water of ships that docked on the Amazon coast. Phytoplankton samples were collected from 25 ships between 2012 and 2014, revealing 215 identified species, mostly comprising oceanic planktonic marine species. However, several coastal and freshwater species not yet documented on the Maranhão coast were also observed. The identification of several coastal and freshwater species not yet recorded for Amazonian environments in the ballast water of the Ponta da Madeira Maritime Terminal (TMPM), as well as toxic microalgae genera such as the dinoflagellates Alexandrium and Gymnodinium and of some diatom species from the genus Pseudo-nitzchia, raises concerns regarding the possibility of introducing species. This indicates that ballast water can be responsible for the introduction of alien species in Amazonian aquatic environments, thereby highlighting the TMPM as a critical hotspot in the Amazonian region.

Ecological associations distribution modelling of marine plankton at a global scale.

Marine plankton communities form intricate networks of interacting organisms at the base of the food chain, and play a central role in regulating ocean biogeochemical cycles and climate. However, predicting plankton community shifts in response to climate change remains challenging. While species distribution models are valuable tools for predicting changes in species biogeography under climate change scenarios, they generally overlook the key role of biotic interactions, which can significantly shape ecological processes and ecosystem responses. Here, we introduce a novel statistical framework, association distribution modelling (ADM), designed to model and predict ecological associations distribution in space and time. Applied on a Tara Oceans genome-resolved metagenomics dataset, the present-day biogeography of ADM-inferred marine plankton associations revealed four major biogeographic biomes organized along a latitudinal gradient. We predicted the evolution of these biome-specific communities in response to a climate change scenario, highlighting differential responses to environmental change. Finally, we explored the functional potential of impacted plankton communities, focusing on carbon fixation, outlining the predicted evolution of its geographical distribution and implications for ecosystem function.This article is part of the theme issue 'Connected interactions: enriching food web research by spatial and social interactions'.

The dynamics of evolutionary branching in an ecological model

Eco-evolutionary modelling involves the coupling of ecological equations to evolutionary ones. The interaction between ecological dynamics and evolutionary processes is essential to simulating evolutionary branching, a precursor to speciation. The creation and maintenance of biodiversity in models depends upon their ability to capture the dynamics of evolutionary branching. Understanding these systems requires low-dimension models that are amenable to analysis. The rapid reproduction rates of marine plankton ecosystems and their importance in determining the fluxes of climatically important gases between the ocean and atmosphere suggest that the next generation of global climate models needs to incorporate eco-evolutionary models in the ocean. This requires simple population-level models, that can represent such eco-evolutionary processes with orders of magnitude fewer equations than models that follow the dynamics of individual phenotypes. We present a general framework for developing eco-evolutionary models and consider its general properties. This framework defines a fitness function and assumes a beta distribution of phenotype abundances within each population. It simulates the change in total population size, the mean trait value, and the trait differentiation, from which the variance of trait values in the population may be calculated. We test the efficacy of the eco-evolutionary modelling framework by comparing the dynamics of evolutionary branching in a six-equation eco-evolutionary model that has evolutionary branching, with that of an equivalent one-hundred equation model that simulates the dynamics of every phenotype in the population. The latter model does not involve a population fitness function, nor does it assume a distribution of phenotype abundance across trait values. The eco-evolutionary population model and the phenotype model produce similar evolutionary branching, both qualitatively and quantitatively, in both symmetric and asymmetric fitness landscapes. In order to better understand the six-equation model, we develop a heuristic three-equation eco-evolutionary model. We use the density-independent mortality parameter as a convenient bifurcation parameter, so that differences in evolutionary branching dynamics in symmetric and asymmetric fitness landscapes may be investigated. This model shows that evolutionary branching of a stable population is flagged by a zero in the local trait curvature; the trait curvature then changes sign from negative to positive and back to negative, along the solution. It suggests that evolutionary branching points may be generated differently, with different dynamical properties, depending upon, in this case, the symmetry of the system. It also suggests that a changing environment, that may change attributes such as mortality, could have profound effects on an ecosystem’s ability to adapt. Our results suggest that the properties of the three-dimensional model can provide useful insights into the properties of the higher-dimension models. In particular, the bifurcation properties of the simple model predict the processes by which the more complicated models produce evolutionary branching points. The corresponding bifurcation properties of the phenotype and population models, evident in the dynamics of the phenotype distributions they predict, suggest that our eco-evolutionary modelling framework captures the essential properties that underlie the evolution of phenotypes in populations.

Multi-scale superpixel-based nearest subspace classifier for mucilage detection from hyperspectral PRISMA data

Hyperspectral imaging has a critical role in observing the Earth's surface, providing images with rich spectral information. As a result, it has become an essential tool for monitoring and addressing environmental issues such as pollution, water balance, and climate change. Among these challenges, marine pollution poses a significant ecological threat, as evidenced by the recent mucilage incident in Turkey in April 2021. Mucilage, a dense mucus-like substance resulting from the overgrowth of marine plankton and microorganisms, detrimentally affects marine ecosystems when its levels surge. Traditional mucilage detection involves labour-intensive sampling and laboratory analysis, rendering it impractical for vast marine environments. Remote sensing techniques offer a promising alternative for automated mucilage detection from satellite imagery. In this study, we propose a multi-scale superpixel-based classification approach for mucilage detection, using the PRISMA satellite's hyperspectral mucilage datasets captured over the Sea of Marmara. Our method performs classification by analyzing the closeness between the subspace spanned by the samples in the superpixel and the subspace spanned by the within-class training samples. We formulate the solution to this approach via a Canonical Correlation Analysis framework and show that our proposed method outperforms its competitors, especially when the training data is limited. Our comprehensive experiments include assessing the transferability of classification methods on datasets collected from different locations and at different times. We compared the performance of our proposed method with state-of-the-art spectral-spatial classification methods, including deep learning-based random patches network (RPNet), structural-kernel collaborative representation (SKCR), and window based nearest subspace classifier (WBNSC). The results show that the proposed method outperforms existing techniques in most cases. The datasets and source code are publicly available on GitHub at https://github.com/kgtoker/MSBNSC, enabling more comprehensive access and collaboration in environmental monitoring efforts.

Bioactive peptides from by-products of shrimp processing: A review

Currently, the mismanagement of marine by-products (head, skin, guts, blood, and bones) is a problem for the seafood processing industry, causing economic losses and environmental problems. Shrimp is a high-protein marine plankton species, and after processing, 45% of the total weight is discarded. Therefore, processes must be developed to recover biomolecules from this waste. Hydrolysis of shrimp by-products is an efficient way to add value to the protein for the extraction of bioactive peptides. The present review focuses on recent research on the use of marine by-products to obtain bioactive peptides, especially those from shrimp waste, and discusses their benefits for human health. Protein hydrolysates from shrimp by-products are a viable and technological strategy to obtain peptides of different sizes and improved antioxidant, anti-hypertensive, anti-inflammatory, and hypocholesterolaemic activities. Therefore, the reuse and valorisation of shrimp by-products by obtaining bioactive peptides is an active research area, with potential applications and beneficial effects for human health, the environment, and the economy. However, further studies are needed to ensure their safe use, and to understand their mechanism of action.

Marine copepod culture as a potential source of bioplastic-degrading microbiome: The case of poly(butylene succinate-co-adipate)

The poly(butylene succinate-co-adipate) (PBSA) is emerging as environmentally sustainable polyester for applications in marine environment. In this work the capacity of microbiome associated with marine plankton culture to degrade PBSA, was tested. A taxonomic and functional characterization of the microbiome associated with the copepod Acartia tonsa, reared in controlled conditions, was analysed by 16S rDNA metabarcoding, in newly-formed adult stages and after 7 d of incubation. A predictive functional metagenomic profile was inferred for hydrolytic activities involved in bioplastic degradation with a particular focus on PBSA. The copepod-microbiome was also characterized in newly-formed carcasses of A. tonsa, and after 7 and 33 d of incubation in the plankton culture medium. Copepod-microbiome showed hydrolytic activities at all developmental stages of the alive copepods and their carcasses, however, the evenness of the hydrolytic bacterial community significantly increased with the time of incubation in carcasses. Microbial genera, never described in association with copepods: Devosia, Kordia, Lentibacter, Methylotenera, Rheinheimera, Marinagarivorans, Paraglaciecola, Pseudophaeobacter, Gaiella, Streptomyces and Kribbella sps., were retrieved. Kribbella sp. showed carboxylesterase activity and Streptomyces sp. showed carboxylesterase, triacylglycerol lipase and cutinase activities, that might be involved in PBSA degradation. A culturomic approach, adopted to isolate bacterial specimen from carcasses, led to the isolation of the bacterial strain, Vibrio sp. 01 tested for the capacity to promote the hydrolysis of the ester bonds. Granules of PBSA, incubated 82 d at 20 °C with Vibrio sp. 01, were characterized by scanning electron microscopy, infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry, showing fractures compared to the control sample, and hydrolysis of ester bonds. These preliminary results are encouraging for further investigation on the ability of the microbiome associated with plankton to biodegrade polyesters, such as PBSA, and increasing knowledge on microorganisms involved in bioplastic degradation in marine environment.

Coastal Eukaryotic Plankton Diversity of the Southern Adriatic as Revealed by Metabarcoding

Plankton studies serve as a basis for marine ecosystem research, but knowledge of marine plankton is still incomplete due to its extreme taxonomic and functional complexity. The application of metabarcoding is very valuable for the characterisation of the plankton community. The plankton community of the Southern Adriatic is subject to strong environmental fluctuations and changes, which underlines the need for frequent, reliable and comprehensive characterisation of the plankton. The aim of this study was to determine the taxonomic composition and seasonal distribution of eukaryotic plankton in the Southern Adriatic. Plankton samples were collected monthly for one year at the coastal station of the Southern Adriatic and metabarcoding was used for taxonomic identification. The results showed a high taxonomic diversity and dynamic seasonal distribution patterns for both the protist and metazoan plankton communities. Metabarcoding revealed both the core, year-round plankton community and previously unrecorded plankton organisms in the Southern Adriatic. The results provide for the first time a comprehensive overview of the plankton community in this area by metabarcoding. The identified seasonal patterns of plankton genera and species in the Southern Adriatic will contribute to the understanding of plankton interactions and future changes in community diversity characterisation.

Principal Component Analysis–Based Feature Recognition Technology for Marine Plankton Images in IoT Systems

Abstract To improve the accuracy of traditional plankton image feature recognition techniques, a principal component analysis (PCA)–based method for plankton image feature recognition in Internet of Things (IoT) systems was designed and proposed. According to the characteristics of a microscopic image of marine living plankton with much noise, a noise suppression method based on wavelet is established to meet the needs of edge information retention and stability in image processing. At the same time, the adaptive threshold gray segmentation, mathematical morphology operation, and canny edge detection operator are combined to complete the marine plankton image segmentation. Based on the global feature and texture information of contours, the feature set is composed. At the same time, PCA is used to reduce the dimensionality of the feature space and complete the feature recognition of plankton images in the IoT system. The test results show that this method has higher accuracy, shorter recognition time, lower cost, and certain applicability.

Distinct responses to warming within picoplankton communities across an environmental gradient.

Picophytoplankton are a ubiquitous component of marine plankton communities and are expected to be favored by global increases in seawater temperature and stratification associated with climate change. Eukaryotic and prokaryotic picophytoplankton have distinct ecology, and global models predict that the two groups will respond differently to future climate scenarios. At a nearshore observatory on the Northeast US Shelf, however, decades of year-round monitoring have shown these two groups to be highly synchronized in their responses to environmental variability. To reconcile the differences between regional and global predictions for picophytoplankton dynamics, we here investigate the picophytoplankton community across the continental shelf gradient from the nearshore observatory to the continental slope. We analyze flow cytometry data from 22 research cruises, comparing the response of picoeukaryote and Synechococcus communities to environmental variability across time and space. We find that the mechanisms controlling picophytoplankton abundance differ across taxa, season, and distance from shore. Like the prokaryote, Synechococcus, picoeukaryote division rates are limited nearshore by low temperatures in winter and spring, and higher temperatures offshore lead to an earlier spring bloom. Unlike Synechococcus, picoeukaryote concentration in summer decreases dramatically in offshore surface waters and exhibits deeper subsurface maxima. The offshore picoeukaryote community appears to be nutrient limited in the summer and subject to much greater loss rates than Synechococcus. This work both produces and demonstrates the necessity of taxon- and site-specific knowledge for accurately predicting the responses of picophytoplankton to ongoing environmental change.

Biogeographic response of marine plankton to Cenozoic environmental changes.

In palaeontological studies, groups with consistent ecological and morphological traits across a clade's history (functional groups)1 afford different perspectives on biodiversity dynamics than do species and genera2,3, which are evolutionarily ephemeral. Here we analyse Triton, a global dataset of Cenozoic macroperforate planktonic foraminiferal occurrences4, to contextualize changes in latitudinal equitability gradients1, functional diversity, palaeolatitudinal specialization and community equitability. We identify: global morphological communities becoming less specialized preceding the richness increase after the Cretaceous-Palaeogene extinction; ecological specialization during the Early Eocene Climatic Optimum, suggesting inhibitive equatorial temperatures during the peak of the Cenozoic hothouse; increased specialization due to circulation changes across the Eocene-Oligocene transition, preceding the loss of morphological diversity; changes in morphological specialization and richness about 19 million years ago, coeval with pelagic shark extinctions5; delayed onset of changing functional group richness and specialization between hemispheres during the mid-Miocene plankton diversification. The detailed nature of the Triton dataset permits a unique spatiotemporal view of Cenozoic pelagic macroevolution, in which global biogeographic responses of functional communities and richness are decoupled during Cenozoic climate events. The global response of functional groups to similar abiotic selection pressures may depend on the background climatic state (greenhouse or icehouse) to which a group is adapted.