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Zinc (Zn) is vital to marine organisms. Its active uptake by phytoplankton results in a substantial depletion of dissolved Zn, and Zn bound to particulate organic matter replenishes dissolved Zn in the ocean through remineralization. However, we found that particulate Zn changes from Zn bound to phosphoryls in cells to recalcitrant inorganic pools that include biogenic silica, clays, and iron, manganese, and aluminum oxides in the Southern Ocean water column. The abundances of inorganic pools increase with depth and are the only phases preserved in sediments. Changes in the particulate-Zn speciation influence Zn bioavailability and explain the decoupling of Zn and phosphorus and the correlation of Zn and silicon in the water column. These findings reveal a new dimension to the ocean Zn cycle, implicating an underappreciated role of inorganic Zn particles and their impact on biological productivity. [ABSTRACT FROM AUTHOR]

The high rate of biological productivity in the North Atlantic is stimulated by the advective supply of nutrients into the region via the Gulf Stream (nutrient stream). It has been proposed that the projected future decline in the Atlantic Meridional Overturning Circulation (AMOC) will cause a reduction in nutrient supply and resulting productivity. In this work, we examine how the nutrient stream changed over the Younger Dryas climate reversal that marked the transition out of the last ice age. Gulf Stream nutrient content decreased, and oxygen content increased at the Florida Straits during this time of weakened AMOC. The decreased nutrient stream was accompanied by a reduction in biological productivity at higher latitudes in the North Atlantic, which supports the link postulated in theoretical and modeling studies. [ABSTRACT FROM AUTHOR]

The global oceanÕs oxygen inventory is declining in response to global warming, but the future of the low-oxygen tropics is uncertain. We report new evidence for tropical oxygenation during the Paleocene-Eocene Thermal Maximum (PETM), a warming event that serves as a geologic analog to anthropogenic warming. Foraminifera-bound nitrogen isotopes indicate that the tropical North Pacific oxygen-deficient zone contracted during the PETM. A concomitant increase in foraminifera size implies that oxygen availability rose in the shallow subsurface throughout the tropical North Pacific. These changes are consistent with ocean model simulations of warming, in which a decline in biological productivity allows tropical subsurface oxygen to rise even as global ocean oxygen declines. The tropical oxygen increase may have helped avoid a mass extinction during the PETM. [ABSTRACT FROM AUTHOR]

Organisms use energy to grow and reproduce, so the processes of energy metabolism and biological production should be tightly bound. On the basis of this tenet, we developed and tested a new theory that predicts the relationships among three fundamental aspects of life: metabolic rate, growth, and reproduction. We show that the optimization of these processes yields the observed allometries of metazoan life, particularly metabolic scaling. We conclude that metabolism, growth, and reproduction are inextricably linked; that together they determine fitness; and, in contrast to longstanding dogma, that no single component drives another. Our model predicts that anthropogenic change will cause animals to evolve decreased scaling exponents of metabolism, increased growth rates, and reduced lifetime reproductive outputs, with worrying consequences for the replenishment of future populations. [ABSTRACT FROM AUTHOR]

Low biological productivity causes ecosystem energy deficiency. Sansha Bay is an important spawning and nursery ground for migratory fish in the East China Sea (ECS). There is significant mariculture in this area, but stock enhancement programs and seasonal fishery closures have failed to recover populations of the commercially important species, Larimichthys crocea. We want to figure out the potential reason of unsuccessful L. crocea resource in recent 30 years. In this study, the trophic status of L. crocea, the food source proportions of L. crocea and zooplankton, and the food web structure and functioning of Sansha Bay was analyzed. A high nutrient low chlorophyll phenomenon was observed: this prevented harmful algal blooms, and phytoplankton growth was restrained by intensive macroalgal culture, resulting in a low abundance of zooplankton in Sansha Bay. Phytoplankton was the most important food source of zooplankton, and zooplankton was the greatest food source of juvenile L. crocea. Analyzed L. crocea suffered from starvation. Crucially, most of the phytoplankton was not used efficiently in the Sansha Bay ecosystem. This study suggests that trophic bottleneck, caused by food limitation, is a potential reason for unsuccessful fishery recovery in enclosed bay with macroalgal culture. [ABSTRACT FROM AUTHOR]

The article offers information on the climate-driven aerobic habitat loss in the California, U.S. It analyzes the past regional variability and future changes in the Metabolic Index, a species-specific measure of the environment's capacity to meet temperature-dependent organismal oxygen demand, disrupting ecological interactions throughout the region.

Climate change projections to the year 2100 may miss physical-biogeochemical feedbacks that emerge later from the cumulative effects of climate warming. In a coupled climate simulation to the year 2300, the westerly winds strengthen and shift poleward, surface waters warm, and sea ice disappears, leading to intense nutrient trapping in the Southern Ocean. The trapping drives a global-scale nutrient redistribution, with net transfer to the deep ocean. Ensuing surface nutrient reductions north of 30°S drive steady declines in primary production and carbon export (decreases of 24 and 41%, respectively, by 2300). Potential fishery yields, constrained by lower–trophic-level productivity, decrease by more than 20%globally and by nearly 60% in the North Atlantic. Continued high levels of greenhouse gas emissions could suppress marine biological productivity for a millennium. [ABSTRACT FROM AUTHOR]

The article discusses the study which shows the increased concentration of radium (Ra)-228 isotopes due to increased intensification of shelf-derived materials in the central Arctic Ocean. Topics mentioned include the rising temperature that alter the nutrient cycles in the continental shelf, the mass balance model that shows the increase of Ra, and the effect of the changes in biological productivity and species aseemblages.

The article focuses on study related to response of temporal variation in pelagic food chain length to environmental change. It mentions that climate variability alters nitrogen cycling, primary productivity, and dissolved oxygen concentration in marine ecosystems. It also mentions the role of variability on food chain length (FCL) in the California Current (CC).

The search for predictions of species diversity across environmental gradients has challenged ecologists for decades. The humped-back model (HBM) suggests that plant diversity peaks at intermediate productivity; at low productivity few species can tolerate the environmental stresses, and at high productivity a few highly competitive species dominate. Over time the HBM has become increasingly controversial, and recent studies claim to have refuted it. Here, by using data from coordinated surveys conducted throughout grasslands worldwide and comprising a wide range of site productivities, we provide evidence in support of the HBM pattern at both global and regional extents. The relationships described here provide a foundation for further research into the local, landscape, and historical factors that maintain biodiversity. [ABSTRACT FROM AUTHOR]

After a decade with nine of the lowest arctic sea-ice minima on record, including the historically low minimum in 2012, we synthesize recent developments in the study of ecological responses to sea-ice decline. Sea-ice loss emerges as an important driver of marine and terrestrial ecological dynamics, influencing productivity, species interactions, population mixing, gene flow, and pathogen and disease transmission. Major challenges in the near future include assigning clearer attribution to sea ice as a primary driver of such dynamics, especially in terrestrial systems, and addressing pressures arising from human use of arctic coastal and near-shore areas as sea ice diminishes. [ABSTRACT FROM AUTHOR]

Catastrophic ecological regime shifts may be announced in advance by statistical early warning signals such as slowing return rates from perturbation and rising variance. The theoretical background for these indicators is rich, but real-world tests are rare, especially for whole ecosystems. We tested the hypothesis that these statistics would be early warning signals for an experimentally induced regime shift in an aquatic food web. We gradually added top predators to a lake over 3 years to destabilize its food web. An adjacent lake was monitored simultaneously as a reference ecosystem. Warning signals of a regime shift were evident in the manipulated lake during reorganization of the food web more than a year before the food web transition was complete, corroborating theory for leading indicators of ecological regime shifts. [ABSTRACT FROM AUTHOR]

The diversity and complexity of food webs (the networks of feeding relationships within an ecological community) are considered to be important factors determining ecosystem function and stability. However, the biological processes driving these factors are poorly understood. Resource quality affects species interactions by limiting energy transfer to consumers and their predators, affecting life history and morphological traits. We show that differences in plant traits affect the structure of an entire food web through a series of direct and indirect effects. Three trophic levels of consumers were influenced by plant quality, as shown by quantitative herbivore-parasitoid-secondary parasitoid food webs. We conclude, on the basis of our data, that changes in the food web are dependent on both trait- and density-mediated interactions among species. [ABSTRACT FROM AUTHOR]

Biogeochemical rate processes in the Southern Ocean have an important impact on the global environment. Here, we summarize an extensive set of published and new data that establishes the pattern of gross primary production and net community production over large areas of the Southern Ocean. We compare these rates with model estimates of dissolved iron that is added to surface waters by aerosols. This comparison shows that net community production, which is comparable to export production, is proportional to modeled input of soluble iron in aerosols. Our results strengthen the evidence that the addition of aerosol iron fertilizes export production in the Southern Ocean. The data also show that aerosol iron input particularly enhances gross primary production over the large area of the Southern Ocean downwind of dry continental areas. [ABSTRACT FROM AUTHOR]

Episodic eddy-driven upwelling may supply a significant fraction of the nutrients required to sustain primary productivity of the subtropical ocean. New observations in the northwest Atlantic reveal that, although plankton blooms occur in both cyclones and mode-water eddies, the biological responses differ. Mode-water eddies can generate extraordinary diatom biomass and primary production at depth, relative to the time series near Bermuda. These blooms are sustained by eddy/wind interactions, which amplify the eddy-induced upwelling. In contrast, eddy/wind interactions dampen eddy-induced upwelling in cyclones. Carbon export inferred from oxygen anomalies in eddy cores is one to three times as much as annual new production for the region. [ABSTRACT FROM AUTHOR]

Biological nitrogen (N2) fixation is important in controlling biological productivity and carbon flux in the oceans. Unicellular N2-fixing cyanobacteria have only recently been discovered and are widely distributed in tropical and subtropical seas. Metagenomic analysis of flow cytometry-sorted cells shows that unicellular N2-fixing cyanobacteria in "group A" (UGYN-A) lack genes for the oxygen-evolving photosystem II and for carbon fixation, which has implications for oceanic carbon and nitrogen cycling and raises questions regarding the evolution of photosynthesis and N2 fixation on Earth. [ABSTRACT FROM AUTHOR]

Measurements in a coastal inlet revealed turbulence that was three to four orders of magnitude larger during the dusk ascent of a dense acoustic-scattering layer of krill than during the day, elevating daily-averaged mixing in the inlet by a factor of 100. Because vertically migrating layers of swimming organisms are found in much of the ocean, biologically generated turbulence may affect (i) the transport of inorganic nutrients to the often nutrient-depleted surface layer from underlying nutrient-rich stratified waters to affect biological productivity and (ii) the exchange of atmospheric gases such as CO2 with the stratified ocean interior, which has no direct communication with the atmosphere. [ABSTRACT FROM AUTHOR]

Theory predicts, and recent empirical studies have shown, that the diversity of plant species determines the diversity of associated herbivores and mediates ecosystem processes, such as aboveground net primary productivity (ANPP). However, an often-overlooked component of plant diversity, namely population genotypic diversity, may also have wide-ranging effects on community structure and ecosystem processes. We showed experimentally that increasing population genotypic diversity in a dominant old-field plant species, Solidago altissima, determined arthropod diversity and community structure and increased ANPP. The effects of genotypic diversity on arthropod diversity and ANPP were comparable to the effects of plant species diversity measured in other studies. [ABSTRACT FROM AUTHOR]

Age estimates for the opening of Drake Passage range from 49 to 17 million years ago (Ma), complicating interpretations of the relationship between ocean circulation and global cooling. Secular variations of neodymium isotope ratios at Agulhas Ridge (Southern Ocean, Atlantic sector) suggest an influx of shallow Pacific seawater approximately 41 Ma. The timing of this connection and the subsequent deepening of the passage coincide with increased biological productivity and abrupt climate reversals. Circulation/productivity linkages are proposed as a mechanism for declining atmospheric carbon dioxide. These results also indicate that Drake Passage opened before the Tasmanian Gateway, implying the late Eocene establishment of a complete circum-Antarctic pathway. [ABSTRACT FROM AUTHOR]

The article cites several studies relating to food webs. These studies precipitated a convergence of different approaches, mathematical treatments, descriptive work, manipulative field studies and a formal treatment of energy flow and matter. This in turn allowed mapping of the interrelationships among the structure of an ecological community, its stability and the processes occurring within the ecosystem, that is, construction of a food web. The food web approach, with its focus on static structure and reliance on stability or persistence of species, seemed ill-equipped for analyzing these more dynamic topics. Over time, food webs change in species composition and in population life history parameters and abundances, and individual organisms within the web change in growth, size and behavior. Dynamic relationships among different levels of the biological hierarchy govern food web structure and stability. Field observations and theoretical models show that environmental heterogeneity creates subsystems of interacting species within food webs, especially at the lower trophic levels.

The article discusses a model study which demonstrates a slow but extensive nutrient removal from surface ocean within long-term climatic change, focusing on a study by Moore and colleagues within the issue suggesting long-term changes in ocean productivity. Moore and colleagues demonstrates the potential of changes in primary production and ocean circulation to reorganize global nutrient distribution, predicting a reduction in primary marine productivity.

The article discusses a report within the issue regarding ecology research by P. B. Reich and colleagues investigating the impact of biodiversity loss on ecosystem productivity. The author notes the change in perspective among ecologists and evolutionary biologists regarding biodiversity and discusses insights into how much diversity is needed to maintain the productivity of an ecosystem from Reich and colleagues' study. A diagram illustrating the relationship between diversity and ecosystem functioning, which is based on a reanalysis of results from two long-term studies of grassland plants conducted at the Ceder Creek Ecosystem Science Reserve in Minnesota.

The article discusses the relationship between biodiversity and ecosystem productivity. According to the author, the impact of landscape modification and climate change is a concern for a variety of reasons, including the potential loss of goods and services derived from biodiversity. He notes that the relation of biodiversity to ecosystem function and productivity is a widely studied and highly controversial issue and discusses a report within the issue by Adler and colleagues who demonstrate that rather than being a dominant relationship, the modal productivity-biodiversity pattern in nature is rare.

The article analyzes how species coevolve and shape complex webs of mutualistic interaction. Researchers have addressed an important component of this problem by asking if mutualistic interactions involving dozens or even hundreds of plant and animal species coevolve in a way that leads to a predictable pattern of links among species. Some ecosystems, such as tropical rain forests, rely so heavily on these interactions that they would collapse in their absence, because plant reproduction would cease. Within these webs, it is rare for a local plant species and animal species to be so reciprocally specialized that neither interacts with other species. Most studies of nested and compartmentalized webs have been based on qualitative data, in which all connections between species are given equal weight. Recent studies of food webs with antagonistic interactions between species have begun to explore webs in which the connections among species are weighted by the relative frequency with which a species interacts with other species.

This article reports that three-quarters of the zooplankton species in the southern Caspian were annihilated, sending a shock wave through the food chain that dealt the biggest blow to kilka, a favorite of Iran's fishing industry. The aggressor, one of the most feared and reviled invasive species--the comb jelly Mnemiopsis leidyi--had transformed the world's largest lake into a killing field. The voracious jelly seemed to be an unstoppable menace. In the late 1990s, another comb jelly, Beroe ovata, put an end to Mnemiopsis's romp there by eating its cousins and bringing the population under control. Any delay in joining battle with Mnemiopsis is bad news for the Caspian, where environmental degradation and overfishing imperil sturgeons, prized for their caviar, and a virus has hammered the endangered Caspian seal. Within 2 weeks after birth, the hermaphrodite reaches sexual maturity and can produce thousands of eggs each day. Although its main food is zooplankton, Mnemiopsis also eats fish eggs and larvae. INSET: The Sturgeon's Last Stand.

This article reports that researchers hope that new funds, better management plans, and the latest science will help them establish the largest network of marine protected areas in the U.S. The 1800-kilometer California coastline supports a spectacular diversity of marine life. So does a sea floor that plunges just offshore to nearly 2600 meters, with sea-grass beds and kelp forests giving way to submarine canyons and deep rock reefs. Add in seasonal winds and complex ocean currents that churn up nutrients for thousands of species from sharks and tuna to squid and rockfish, and the result is an incredibly rich ecosystem and one of the most productive fisheries in the nation.

The article focuses on the benefits from phosphorus in the biological, industrial and marine processes, and discusses some problems concerning soil fertilization and industrial use of phosphorus. It states that phosphorus is considered as one of the rarest, biological nutrients on Earth, which feeds biological production in the oceans and plants on lands. It also informs that the nutrient is also required for the formations of bones, teeth, and some shells. However, rampant soil fertilization and industrial use had led to the problem of too much phosphorus in the rivers and estuaries.

The article presents a study which illustrates the reasons behind the increased population of leatherback turtle in the Atlantic Ocean than in the Pacific. The researchers had used the net primary productivity (NPP) in analysing the success rates of turtle population, their migratory patterns, and oceanographic variables. It was found out that turtle populations are regulated by the abundance of zooplankton. It was also discovered that local resources in the Atlantic is higher in the Pacific Ocean.

The article focuses on the measurement of phosphorus in the deep sea. Biological productivity in the ocean, helps control climate on glacial time scales through its effect on the global carbon cycle, The biological productivity is regulated by the availability of nutrients such as phosphorus. Combine measurements of the phosphorus concentration in deep sea sediments from the Atlantic and the Pacific oceans with recent advances in the understanding of phosphorus geochemistry was done by some researchers. This finding supports the Shelf-Nutrient Hypothesis. The hypothesis postulates that phosphorus should be transferred from shallow continentat margins to the deep sea when continental shelves become exposed during glacial sea-level lowstands.

The article presents information related to the structure of food webs and factors that contribute to their stability. Theoretical simulations of consumer and resource species suggest that the population persistence of predator and prey species in food webs increases up to a saturation point as the ratio of the predator-to-prey body mass increases. The saturation point remains high for vertebrates than invertebrates. A survey of body-size distributions in natural food webs reveals that body-size ratios of predators and prey differed across freshwater, marine and terrestrial ecosystems.

Nitrogen-fixing bacteria supply a large fraction of the nitrate input to the upper layer of the ocean, thereby facilitating biological production in surface waters, but quantifying the global flux of this fixed nitrogen has proven to be difficult. Scientists analyze satellite data for a summer phytoplankton bloom in the western tropical North Atlantic and find that ocean color indicative of high values of chlorophyll occurs where anomalies of sea surface height show the presence of warm pools of water.