Marine Photosynthesis Research Articles

A chlorophyll c synthase widely co-opted by phytoplankton.

Marine and terrestrial photosynthesis exhibit a schism in the accessory chlorophyll (Chl) that complements the function of Chl a: Chl b for green plants versus Chl c for most eukaryotic phytoplankton. The enzymes that mediate Chl c biosynthesis have long remained elusive. In this work, we identified the CHLC dioxygenase (Phatr3_J43737) from the marine diatom Phaeodactylum tricornutum as the Chl c synthase. The chlc mutants lacked Chl c, instead accumulating its precursors, and exhibited growth defects. In vitro, recombinant CHLC protein converted these precursors into Chl c, thereby confirming its identity. Phylogenetic evidence demonstrates conserved use of CHLC across phyla but also the existence of distinct Chl c synthases in different algal groups. Our study addresses a long-outstanding question with implications for both contemporary and ancient marine photosynthesis.

Production and cross-feeding of nitrite within Prochlorococcus populations.

Prochlorococcus is an abundant photosynthetic bacterium in the open ocean, where nitrogen (N) often limits phytoplankton growth. In the low-light-adapted LLI clade of Prochlorococcus, nearly all cells can assimilate nitrite (NO2-), with a subset capable of assimilating nitrate (NO3-). LLI cells are maximally abundant near the primary NO2- maximum layer, an oceanographic feature that may, in part, be due to incomplete assimilatory NO3- reduction and subsequent NO2- release by phytoplankton. We hypothesized that some Prochlorococcus exhibit incomplete assimilatory NO3- reduction and examined NO2- accumulation in cultures of three Prochlorococcus strains (MIT0915, MIT0917, and SB) and two Synechococcus strains (WH8102 and WH7803). Only MIT0917 and SB accumulated external NO2- during growth on NO3-. Approximately 20-30% of the NO3- transported into the cell by MIT0917 was released as NO2-, with the rest assimilated into biomass. We further observed that co-cultures using NO3- as the sole N source could be established for MIT0917 and Prochlorococcus strain MIT1214 that can assimilate NO2- but not NO3-. In these co-cultures, the NO2- released by MIT0917 is efficiently consumed by its partner strain, MIT1214. Our findings highlight the potential for emergent metabolic partnerships that are mediated by the production and consumption of N cycle intermediates within Prochlorococcus populations. IMPORTANCE Earth's biogeochemical cycles are substantially driven by microorganisms and their interactions. Given that N often limits marine photosynthesis, we investigated the potential for N cross-feeding within populations of Prochlorococcus, the numerically dominant photosynthetic cell in the subtropical open ocean. In laboratory cultures, some Prochlorococcus cells release extracellular NO2- during growth on NO3-. In the wild, Prochlorococcus populations are composed of multiple functional types, including those that cannot use NO3- but can still assimilate NO2-. We show that metabolic dependencies arise when Prochlorococcus strains with complementary NO2- production and consumption phenotypes are grown together on NO3-. These findings demonstrate the potential for emergent metabolic partnerships, possibly modulating ocean nutrient gradients, that are mediated by cross-feeding of N cycle intermediates.

A linker protein from a red-type pyrenoid phase separates with Rubisco via oligomerizing sticker motifs

The slow kinetics and poor substrate specificity of the key photosynthetic CO2-fixing enzyme Rubisco have prompted the repeated evolution of Rubisco-containing biomolecular condensates known as pyrenoids in the majority of eukaryotic microalgae. Diatoms dominate marine photosynthesis, but the interactions underlying their pyrenoids are unknown. Here, we identify and characterize the Rubisco linker protein PYCO1 from Phaeodactylum tricornutum. PYCO1 is a tandem repeat protein containing prion-like domains that localizes to the pyrenoid. It undergoes homotypic liquid-liquid phase separation (LLPS) to form condensates that specifically partition diatom Rubisco. Saturation of PYCO1 condensates with Rubisco greatly reduces the mobility of droplet components. Cryo-electron microscopy and mutagenesis data revealed the sticker motifs required for homotypic and heterotypic phase separation. Our data indicate that the PYCO1-Rubisco network is cross-linked by PYCO1 stickers that oligomerize to bind to the small subunits lining the central solvent channel of the Rubisco holoenzyme. A second sticker motif binds to the large subunit. Pyrenoidal Rubisco condensates are highly diverse and tractable models of functional LLPS.

Carbon Cycle Responses to Changes in Weathering and the Long‐Term Fate of Stable Carbon Isotopes

AbstractThe causes of CO2 variations over the past million years remain poorly understood. Imbalances between the input of elements from rock weathering and their removal from the atmosphere‐ocean‐biosphere system to the lithosphere likely contributed to reconstructed changes. We employ the Bern3D model to investigate carbon‐climate responses to step‐changes in the weathering input of phosphorus, alkalinity, carbon, and carbon isotope ratio (δ13C) in simulations extending up to 600,000 years. CO2 and climate approach a new equilibrium within a few ten thousand years, whereas equilibrium is established after several hundred thousand years for δ13C. These timescales represent a challenge for the initialization of sediment‐enabled models and unintended drifts may be larger than forced signals in simulations of the last glacial–interglacial cycle. Changes in dissolved CO2 change isotopic fractionation during marine photosynthesis. This causes distinct spatio‐temporal perturbations in δ13C and affects the burial flux of 13C. We force a cost‐efficient emulator, based on the Bern3D results, with contrasting literature‐based weathering histories over the last 800 thousand years. Glacial–interglacial amplitudes of up to 30 ppm in CO2, 0.05‰ in δ13C, and ∼15 mmol m−3 in deep ocean are emulated for changes in carbonate rock weathering. Plausible input from the decomposition of organic matter on shelves causes variations of up to 10 ppm in CO2, 0.09‰ in δ13C, and 5 mmol m−3 in , highlighting the non‐negligible effect of weathering‐burial imbalances.

Fragility of marine photosynthesis

Ecosystem fragility is an often used term in oceanography yet to this day it lacks a precise and widely accepted definition. Defining and subsequently quantifying fragility would be of great value, for such measures could be used to objectively ascertain the level of risk marine ecosystems face. Risk assessments could further be used to define the level of protection a given ocean region requires from economic activity, such as fisheries. With this aim we introduce to the oceanographic literature the concepts of marginal production and fragility, which we define for marine photosynthesis, the base of the oceanic food web. We demonstrate that marine photosynthesis is always fragile with respect to light, implying variability in surface irradiance acts unfavourably on biomass. We also demonstrate that marine photosynthesis can be both fragile and antifragile with respect to the mixed-layer depth, implying variability in mixed-layer depth can act both favourably and unfavourably on biomass. Quantification of marginal production and fragility is presented on data from two open ocean stations: Hawaii Ocean Time Series and Bermuda Atlantic Time-Series Study. Seasonal cycle of biomass is modelled and the effects of primary production fragility are analysed. A new tipping point for marine phytoplankton is identified in the form of a depth horizon. Using the new definitions presented here a rich archive of data can be used straightforwardly to quantify primary production fragility. The definitions can also be used to predict when primary production enters the fragile state during the seasonal cycle.

Widespread phytoplankton blooms triggered by 2019-2020 Australian wildfires.

Droughts and climate-change-driven warming are leading to more frequent and intense wildfires1-3, arguably contributing to the severe 2019-2020 Australian wildfires4. The environmental and ecological impacts of the fires include loss of habitats and the emission of substantial amounts of atmospheric aerosols5-7.Aerosol emissions from wildfires can lead to the atmospheric transport of macronutrients and bio-essential trace metals such as nitrogen and iron, respectively8-10. It has been suggested that the oceanic deposition of wildfire aerosols can relieve nutrient limitations and, consequently, enhance marine productivity11,12, but direct observations are lacking. Here we use satellite and autonomous biogeochemical Argo float data to evaluate the effect of 2019-2020 Australian wildfire aerosol deposition on phytoplankton productivity. We find anomalously widespread phytoplankton blooms from December 2019 to March 2020 in the Southern Ocean downwind of Australia. Aerosol samples originating from the Australian wildfires contained a high iron content and atmospheric trajectories show that these aerosols were likely to be transported to the bloom regions, suggesting that the blooms resulted from the fertilization of the iron-limited waters of the Southern Ocean. Climate models project more frequent and severe wildfires in many regions1-3. A greater appreciation of the links between wildfires, pyrogenic aerosols13, nutrient cycling and marine photosynthesis could improve our understanding of the contemporary and glacial-interglacial cycling of atmospheric CO2 and the global climate system.

Plastic and Toxic Chemical-Induced Ocean Acidification Is Causing a Plankton Crisis and Will Devastate Humanity in the Next 25 Years.

Marine plants and animals should be thriving in ocean waters because of the current high concentrations of carbon dioxide and nutrients along with slightly elevated temperatures - but they are not. We have lost 50% of all marine life over the last 70 years; this decline is continuing today at a rate of 1% year on year. The GOES team has used its collective professional and academic experience to undertake analysis of peer- reviewed and published data to explore the reasons for this decline and its implications for climate and humanity. In our view, this loss of marine life is directly related to the presence of toxic chemicals and plastic which started to appear with the ‘chemical revolution’ in the1950’s. There is no doubt that tiny ocean planktonic plants and animals are key to regulating our climate, but this keystone of the planet’s largest ecosystem seems to be ignored as one of the tools to address climate change. Every second breath we take comes from marine photosynthesis, a process which also uses 60-90% of our carbon dioxide. Now that we have lost 50% of a key climate regulator, surely it is time to stop, take a fresh look at ocean chemistry and biodiversity and ask ourselves some fundamental questions: Why have we lost this level of marine life? Why is the decline continuing? What does this mean for our climate and humanity? Of particular concern from a climate change perspective is the level of carbonic acid in the oceans. This carbonic acid is created when atmospheric carbon dioxide dissolves into the oceans. In the 1940’s, ocean pH was 8.2, but in 2020, pH had dropped to 8.04, indicating that the oceans are becoming more acidic. If there are not enough plants to use up carbon, the unused carbonic acid moves the pH downwards. Reports from respected institutes around the globe flag an acceleration of the ocean acidification process. This decline will result in the loss of more marine plants and animals, especially those that have carbonate shells and body structures (aragonite) based. These same reports forecast that in 25 years (by 2045), pH will drop to 7.95, and estimate that with this, 80% to 90% of all remaining marine life will be lost. The GOES team’s opinion is that this is a tipping point: a planetary boundary which must not be exceeded if humanity is to survive. No ecosystem can survive a 90% loss; the result is a trophic cascade collapse. We will lose all the corals, whales, seals, birds, fish and food supply for 2 billion people – an outcome worse than climate change. Let’s be clear: If by some miracle the world achieves net zero by 2045, evidence from the Intergovernmental Panel on Climate Change (IPCC) BIOACID report [1] demonstrates that this reduction will not be enough to stop a drop in ocean pH to 7.95. If the level of marine life (both plant and animal) is reduced, then the oceans’ ability to lockout carbon into the abyss is depleted. It is clear to the GOES team that if we only pursue carbon mitigation strategies and don’t do more to regenerate plant and animal life in oceans, we will reach a tipping point: a planetary boundary from which there will be no return, because all life on Earth depends upon the largest ecosystem on the planet. Humanity will suffer terribly from global warming, but it must be understood that the oceans are already showing signs of instability today at pH 8.04, (the start of the tipping point) and in 25 years when the pH has dropped to pH 7.95 represents the end point, the point of no return.

Validation of parameters and protocols derived from chlorophyll a fluorescence commonly utilised in marine ecophysiological studies.

This study documents the first validation of the suitability of the most common parameters and protocols used in marine ecophysiology to characterise photosynthesis by means of chlorophyll a fluorescence tools. We demonstrate that the effective yield of PSII (ΔF /F m ') is significantly underestimated when using short inductions times (≤1 min) following the rapid light curve protocol (RLC). The consequent electron transport rates (ETR) underestimations are species-specific and highly variable with irradiance and the photoacclimatory condition of the sample. Our analysis also questions the use of relative descriptors (relETR), as they not only overestimate photosynthesis, but overlook one of the fundamental components of the photosynthetic response: light absorption regulation. Absorptance determinations were fundamental to characterise the ETR response of low-pigmented seagrass leaves, and also uncovered relevant differences between two coral species and the accclimatory response of a cultured dinoflagellate to temperature. ETR and oxygen evolution determinations showed close correlations for all organisms tested with the expected slope of 4 e- per O2 molecule evolved, when correct photosynthesis inductions and light absorption determinations were applied. However, ETR curves cannot be equated to conventional photosynthetic response to irradiance (P vs E ) curves, and caution is needed when using ETR to characterise photosynthesis rates above photosynthesis saturation (E k ). This validation strongly supports the utility of fluorescence tools, underlining the need to correct two decades of propagation of erroneous concepts, protocols and parameters in marine eco-physiology. We aim also to emphasise the importance of optical descriptions for understanding photosynthesis, and for interpreting fluorescence measurements. In combination with conventional gross photosynthesis (GPS) approaches, optical characterisations open an extraordinary opportunity to determine two central parameters of photosynthesis performance: the quantum yield (φmax ) of the process and its minimum quantum requirements (1/φmax ). The combination of both approaches potentiates the possibilities of chlorophyll a fluorescence tools to characterise marine photosynthesis biodiversity.

Herbivory and its effect on Phanerozoic oxygen concentrations

Abstract The appearance of terrestrial land plants is thought to have accompanied an increase in atmospheric oxygen levels, producing the highest O2 concentrations estimated from the geological record, and marking the transition to a permanently oxygenated deep ocean. This Paleozoic oxygenation event, which likely peaked in the Carboniferous Period, was at least partially mediated by the development of recalcitrant, carbon-rich organic compounds in terrestrial plants. A number of studies have argued that shifts in coal formation and paleogeography led to declining preservation of these compounds on land, depressing oxygen levels in the terminal Paleozoic and early Mesozoic. In contrast, we propose that the evolution and diversification of terrestrial herbivores may have limited transport and long-term burial of terrestrial organic compounds in marine sediments, resulting in less organic carbon burial and attendant declines in atmospheric oxygen. This mechanism suggests that interactions among a triad of biological processes—marine photosynthesis, land plant colonization, and the advent of herbivory—may have dictated the long-term redox state of Earth’s surface environments over the Phanerozoic Eon.

Volcano-stimulated marine photosynthesis.

Lava discharge to the ocean from volcano Kīlauea, Hawai'i, triggers phytoplankton blooms

Diurnal regulation of photosynthetic light absorption, electron transport and carbon fixation in two contrasting oceanic environments

Abstract. Understanding the dynamics of marine phytoplankton productivity requires mechanistic insight into the non-linear coupling of light absorption, photosynthetic electron transport and carbon fixation in response to environmental variability. In the present study, we examined the variability of phytoplankton light absorption characteristics, light-dependent electron transport and 14C-uptake rates over a 48 h period in the coastal subarctic north-east (NE) Pacific. We observed an intricately coordinated response of the different components of the photosynthetic process to diurnal irradiance cycles, which acted to maximize carbon fixation, while simultaneously preventing damage by excess absorbed light energy. In particular, we found diurnal adjustments in pigment ratios, excitation energy transfer to reaction centre II (RCII), the capacity for non-photochemical quenching (NPQ), and the light efficiency (α) and maximum rates (Pmax) of RCII electron transport (ETRRCII) and 14C uptake. Comparison of these results from coastal waters to previous observations in offshore waters of the subarctic NE Pacific provides insight into the effects of iron limitation on the optimization of photosynthesis. Under iron-limited, low-biomass conditions, there was a significant reduction of iron-rich photosynthetic units per chlorophyll a, which was partly offset by higher light absorption and electron transport per photosystem II (PSII). Iron deficiency limited the capacity of phytoplankton to utilize peak midday irradiance for carbon fixation and caused an upregulation of photoprotective mechanisms, including NPQ, and the decoupling of light absorption, electron transport and carbon fixation. Such decoupling resulted in an increased electron requirement (Φe,C) and decreased quantum efficiency (ΦC) of carbon fixation at the iron-limited station. In both coastal and offshore waters, Φe,C and ΦC correlated strongly to NPQ, albeit with a significantly different slope. We discuss the implications of our results for the interpretation of bio-optical data and the parameterization of numerical productivity models, both of which are vital tools in monitoring marine photosynthesis over large temporal and spatial scales.

The role of irradiance and C-use strategies in tropical macroalgae photosynthetic response to ocean acidification

Fleshy macroalgae may increase photosynthesis with greater CO2 availability under ocean acidification (OA) and outcompete calcifying macroalgae important for tropical reef accretion. Macroalgae use energy-dependent carbon concentrating mechanisms (CCMs) to take up HCO3−, the dominant inorganic carbon for marine photosynthesis, but carbon-use strategies may depend on the pCO2, pH and irradiance. We examined photosynthesis in eight tropical macroalgae across a range of irradiances (0–1200 μmol photon m−2 s−1), pH levels (7.5–8.5) and CO2 concentrations (3–43 μmol kg−1). Species-specific CCM strategies were assessed using inhibitors and δ13C isotope signatures. Our results indicate that the log of irradiance is a predictor of the photosynthetic response to elevated pCO2 (R2 > 0.95). All species utilized HCO3−, exhibited diverse C-use pathways and demonstrated facultative HCO3− use. All fleshy species had positive photosynthetic responses to OA, in contrast to a split amongst calcifiers. We suggest that shifts in photosynthetically-driven tropical macroalgal changes due to OA will most likely occur in moderate to high-irradiance environments when CCMs are ineffective at meeting the C-demands of photosynthesis. Further, facultative use of HCO3− allows greater access to CO2 for photosynthesis under OA conditions, particularly amongst fleshy macroalgae, which could contribute to enhance fleshy species dominance over calcifiers.

Individual and interactive effects of ocean acidification, global warming, and UV radiation on phytoplankton

Rising carbon dioxide (CO2) concentrations in the atmosphere result in increasing global temperatures and ocean warming (OW). Concomitantly, dissolution of anthropogenic CO2 declines seawater pH, resulting in ocean acidification (OA) and altering marine chemical environments. The marine biological carbon pump driven by marine photosynthesis plays an important role for oceanic carbon sinks. Therefore, how ocean climate changes affect the amount of carbon fixation by primary producers is closely related to future ocean carbon uptake. OA may upregulate metabolic pathways in phytoplankton, such as upregulating s-oxidation and the tricarboxylic acid cycle, resulting in increased accumulation of toxic phenolic compounds. Ocean warming decreases global phytoplankton productivity; however, regionally, it may stimulate primary productivity and change phytoplankton community composition, due to different physical and chemical environmental requirements of species. It is still controversial how OA and OW interactively affect marine carbon fixation by photosynthetic organisms. OA impairs the process of calcification in calcifying phytoplankton and aggravate ultraviolet (UV)-induced harms to the cells. Increasing temperatures enhance the activity of cellular repair mechanisms, which mitigates UV-induced damage. The effects of OA, warming, enhanced exposure to UV-B as well as the interactions of these environmental stress factors on phytoplankton productivity and community composition, are discussed in this review.

The impact of the ‘terrestrialisation process’ in the late Palaeozoic: pCO2, pO2, and the ‘phytoplankton blackout’

With few exceptions, the impact of the evolution of the terrestrial biosphere on the evolution of the marine sphere has been largely ignored. So too has the resulting complementary role of marine photosynthesis and primary productivity in the evolution of atmospheric and oceanic pCO2 and pO2 in response to land–sea interactions. The Early-Middle Palaeozoic invasion of the continents by plants is considered to be responsible for major changes in the carbon cycle and changing values of pO2 and pCO2 in the atmosphere. Some authors have also related the ‘terrestrialisation process’ to the rapid Late Devonian decline of organic-walled phytoplankton (acritarch) diversity. The stratigraphical interval between the Carboniferous and early Triassic, i.e., the late Palaeozoic–Early Mesozoic, is a time period with a very low diversity of organic-walled phytoplankton, and this period was therefore considered by some authors as corresponding to a ‘Phytoplankton Blackout.’ It has been argued that the marine food web during this interval was related to the invasion of land by plants, suggesting that a reduced nutrient input to the ocean by runoff decreased the number of acritarchs and primary production in the marine realm. Subsequently, it has also been suggested that the Phanerozoic phytoplankton record can be correlated with models of pCO2 with high acritarch diversities corresponding to periods of high pCO2. Conversely, the spread of terrestrial forests may have increased weathering rates via deeper rooting, releasing increased amounts of nutrients to the oceans while also increasing atmospheric pCO2.The present paper critically reviews the proposed scenarios and discusses the possible relations between terrestrial and marine ecosystems, in particular the possible impact of the terrestrialisation process on marine phytoplankton. The known Palaeozoic fossil record of the phytoplankton is incomplete to a high degree. It consists almost entirely on the organic-walled fraction, because calcareous and siliceous phytoplankton remain almost unrecorded. In addition, the fossil record solely provides information about the diversity of cysts, but not necessarily precise data of the number and quality of the cyst-producing phytoplanktonic organisms. Taking into consideration that only few modern phytoplankton taxa produce cysts, the absence of cysts in the fossil record does not necessarily imply the absence of phytoplankton. In contrast, the presence of planktotrophic larvae of marine invertebrate organisms indicates that phytoplankton must have been present in the Late Palaeozoic oceans, and the marine trophic web did indeed not collapse in the Late Devonian. The presence and abundance of filter feeding and suspension feeding benthic organisms such as brachiopods, crinoids, sponges and corals also suggest sufficient primary production in the Late Palaeozoic seas.It can be concluded that, although the phytoplankton is largely absent from the fossil record, a ‘phytoplankton blackout’ is unrealistic. A major remaining question is to understand why the cyst production decreased after the Late Devonian and why this might be correlated to changes of pCO2.

Diversity of viral photosystem-I psaA genes.

Marine photosynthesis is one of the major contributors to the global carbon cycle and the world's oxygen supply. This process is largely driven by cyanobacteria, namely Synechococcus and Prochlorococcus. Genes encoding photosystem-II (PSII) reaction center proteins are found in many cyanophage genomes, and are expressed during the infection of their hosts. On the basis of metagenomics, cyanophage photosystem-I (PSI) gene cassettes were recently discovered with two gene arrangements psaJF→C→A→B→K→E→D and psaD→C→A→B. It was suggested that the horizontal transfer of PSII and PSI genes is increasing phage fitness. To better understand their diversity, we designed degenerate primers to cover a wide diversity of organisms, and using PCR we targeted the psaC→A arrangement, which is unique to cyanophages cassettes. We examined viral concentrates from four islands in the Pacific Ocean and found samples containing the psaC→A arrangement. Analyses of the amplified viral psaA gene revealed six subgroups varying in their level of similarity and %G+C content, suggesting that the diversity of cyanophage PSI genes is greater than originally thought.

Research on Electrical Radiation of Marine Functional Materials Based on Negative Feedback Control System

In marine organisms the carbon sink function of shellfish moves in circles. It not only has a great influence on the marine environment, also has the very important significance for the construction of marine ranching to realize the benefits of recycling economy. If the carbon consumption exceeds marine soil and Photosynthesis Carbon input, the marine environment will be subject to different degrees damage, and affect the marine farming production process. Based on this, this paper analyses and studies the shellfish and algae carbon sink function. The first part of this paper introduces shellfish and algae carbon sink regulation function, gives the schematic diagram of carbon cycle, and establishes a column chart through using the preliminary statistical data. The second part establishes the shellfish and algae carbon sink ecological economic system mathematical model in the construction of marine ranching, and gives the adjustment function diagram of ecosystems two coordination function. The third part uses the professional statistical analysis software SAS to draw the shellfish and algae carbon curve of marine ranching construction, which provides theoretical reference for considering the carbon sink function of marine ranching construction.

Viral clones from the GOS expedition with an unusual photosystem-I gene cassette organization

Cyanobacteria have a key role in marine photosynthesis, which contributes to the global carbon cycle and to the world oxygen supply. Genes encoding for photosystem-II (PSII) and photosystem-I (PSI) reaction centers are found in different cyanophage genomes, and it was suggested that the horizontal transfer of these genes might be involved in increasing phage fitness. We have further analyzed a rare viral Global Ocean Sampling (GOS) clone containing PSI genes. This clone contains the unusual PSI gene organization psaD->C->A, as opposed to the more frequently observed viral psaJF->C->A->B->K->E->D organization, and was detected only once in the GOS metagenome. Our analyses identified more occurrences with similar arrangement and indicate that this PSI viral gene organization (now psaD->C->A->B), although rare, is authentic and represents a new PSI gene arrangement.

11 有機合成が先導する海洋光合成を担う多官能性カロテノイドの機能解明(口頭発表の部)

11 有機合成が先導する海洋光合成を担う多官能性カロテノイドの機能解明(口頭発表の部)

The relationships among the three stable isotopes of oxygen in air, seawater and marine photosynthesis

The relationships among the three stable isotopes of oxygen in air, seawater and marine photosynthesis

Could Land Plant Evolution Have Fed the Marine Revolution?

Abstract. The advent of flowering plants on land has been suggested previously as a potential trigger for Cretaceous innovations in the marine realm by providing a greater energetic base for marine ecosystems through a more nutrient-rich terrestrial runoff. The scope of the angiosperm radiation certainly was unprecedented—flowering plants came to represent the large majority of species in all terrestrial floras in a geologically short span of time—and angiosperms possess much higher photosynthetic and hydraulic capacities than all other plants. Angiosperm evolution could have affected both the organic and inorganic content of terrestrial runoff, but the magnitude of these changes is in question. Angiosperms are more productive than other plants, suggesting an increase in organic matter runoff, but that quantity is small in comparison to native marine photosynthesis even in the modern angiosperm-dominated world. Changing the inorganic nutrient content of terrestrial runoff requires changing weathering rate...