应用型海洋药物人才培养模式的研究与实践

针对海洋药物的发展现状及存在问题，从课程体系建立、教学手段的改革入手，探索应用型海洋药物人才的培养模式，提出了一系列具体措施，为全面制订海洋药物专业方向教学计划提供理论依据。     

Emergent effects of global change on consumption depend on consumers and their resources in marine systems

A better understanding of how environmental change will affect species interactions would significantly aid efforts to scale up predictions of near-future responses to global change from individuals to ecosystems. To address this need, we used meta-analysis to quantify the individual and combined effects of ocean acidification (OA) and warming on consumption rates of predators and herbivores in marine ecosystems. Although the primary studies demonstrated that these environmental variables can have direct effects on consumers, our analyses highlight high variability in consumption rates in response to OA and warming. This variability likely reflects differences in local adaptation among species, as well as important methodological differences. For example, our results suggest that exposure of consumers to OA reduces consumption rates on average, yet consumption rates actually increase when both consumers and their resource(s) are concurrently exposed to the same conditions. We hypothesize that this disparity is due to increased vulnerability of prey or resource(s) in conditions of OA that offset declines in consumption. This hypothesis is supported by an analysis demonstrating clear declines in prey survival in studies that exposed only prey to future OA conditions. Our results illustrate how simultaneous OA and warming produce complex outcomes when species interact. Researchers should further explore other potential sources of variation in response, as well as the prey-driven component of any changes in consumption and the potential for interactive effects of OA and warming.

Numerous studies have demonstrated direct effects of ocean acidification (OA) and warming on organismal physiology and performance (1, 2), yet forecasting the emergent ecological effects of environmental change on communities remains a challenge due to the complexity of interactions between species (3–5) and stressors (1, 2, 6–8) in functioning ecosystems. Species interactions have the potential to drive shifts in communities (5, 9–11) or buffer them (5, 12, 13) from environmental change. For example, environmentally mediated increases in growth of some algal species can lead to ecosystem shifts if they outcompete or overgrow other species (14). However, environmentally mediated increases in consumption rates of key herbivores have the potential to limit this overgrowth of algae and the associated community shift (13). Indeed, authors of several of the studies that have revealed potential emergent effects of OA (14–16) or warming (17, 18) on entire marine communities attributed the observed responses at least in part to changes in species interactions. In addition, pronounced shifts in species assemblages and ecosystems during natural, large-scale warming events are often linked to modified species interactions (19, 20). Establishing general patterns of environmental control on species interactions has thus been proposed as a promising avenue for scaling up the effects of environmental change from individuals to ecosystems (9, 21–24).Environmentally mediated changes in trophic interactions may be especially important in determining the effects of global change on ecosystems, due to their potential to have cascading effects on community structure (25, 26). OA (27, 28) and warming (29–31) are generally predicted to alter consumers’ energetic demands, although the effects on consumption will depend on the shape of the performance curves, how close current environmental temperatures are to their performance optima, the magnitude of the environmental change, and their energy allocation strategies (25). The effects of OA on consumption are more likely to vary among taxa with different traits than the effects of warming, which universally affects metabolism. For example, the effects of OA can vary with the degree of calcification or the level of mobility of a given species (1, 2). However, the ability of consumers in nature to sufficiently compensate for changes in energetic demands associated with either OA or warming through altered consumption will also depend on their prey or resources (32–34). For example, an increase in a consumer’s energetic demand could be met through increased ingestion of a given resource. Shifts in the escape response, production of physical or chemical deterrents, or the size or biomass of the resource species driven by environmental change, however, can mediate the outcome (4). Thus, deciphering the environmental controls on trophic interactions requires analysis of both the consumer- and resource-driven components of predation and herbivory in future conditions.In most studies that assess the effects of OA, warming, or both on the consumption rates of marine species, researchers use controlled laboratory experiments that are amenable to meta-analysis. In these experiments, a consumer or resource is most often exposed to current and future environmental conditions for a period of days to months. Thus, the effects measured are primarily plastic and represent an organism’s ability to acclimate physiologically or behaviorally. Often, the consumer is held in treatment conditions and given prey or a resource that has not been acclimated to the experimental conditions (defined here as consumer-only experiments). In contrast, more complex studies (e.g., multispecies mesocosms or studies focused on species interactions or community-level responses) tend to include both the consumer and its resource(s) in the experimental conditions. While the responses in these experiments still represent the physiological or behavioral acclimation of the species involved, these multispecies experiments capture potential emergent effects of environmental change on species interactions that result from the direct effects on both the consumer and the resource. Prior meta-analyses have shown that there can be important variation in the temperature sensitivity of different ecological rates, such as attack rates and escape rates that can influence the emergent effects based on variation in sensitivity among trophic roles (30). Similarly, OA has been shown to affect both predator and prey detection and behavior (35–37), as well as algal traits that could affect herbivory, such as nutritional status or chemical deterrents (37). Most rare are those studies that expose only prey or resources to experimental conditions and then test their vulnerability to predation using a predator or herbivore that is not acclimated to the experimental conditions being tested. In contrast to the consumer-only experiments, these “resource-only” experiments capture how environmental change may affect the vulnerability or palatability of species that serve as resources.Experiments also vary in the complexity of environmental manipulation. Although OA and warming are happening in concert in nature, many early studies focused on the biological effects of OA or warming in isolation. As global change biology has progressed, the focus has shifted toward multifactor studies that incorporate both OA and warming in combination (e.g., factorial experiments). These studies are critically important for forecasting emergent effects, as the combined effects of OA and warming may not be additive (1, 2). This may be especially important if OA and warming have different modes of action on marine organisms (38). Synergisms, in which the effects of OA and warming exacerbate one another, have gained the most attention because of their potential to cause dramatic ecological shifts. However, even with different modes of action, one environmental-change factor may primarily drive an organism’s overall response, leading to unexpected outcomes.We conducted a systematic review (SI Appendix, Fig. S1 and Dataset S1) to assemble a database of published studies (Dataset S2) and conduct a meta-analysis quantifying the individual and combined effects of OA and warming on consumption rates, testing for variation between predator–prey and herbivore–resource interactions. We also tested for variance in the individual and combined effects of each environmental variable on different trophic roles (i.e., studies that exposed only consumers or only resources to treatment conditions prior to measuring consumption) to provide insight on their relative importance in the overall response of predation and herbivory rates in future conditions. We then tested whether taxonomic groups or life stages of interacting organisms explain any remaining variance among underlying studies to aid interpretation and identify gaps in our knowledge that need to be addressed to move the field forward. We also quantified the effects of OA and warming on prey survival in resource-only experiments, as well as the effects on consumer preference of prey or resources raised in ambient or future conditions. Finally, to quantitatively address the potential for nonadditive effects of the combined exposure to OA and warming, we calculated the individual and interactive effects of OA and warming on consumption rates for the subset of studies that factorially manipulated both variables.     

中国远洋船员航海期营养调查

①目的了解中国远洋船员航海期膳食与营养状况。②方法对１８２名船员进行了航海期膳食调查，体格检查和实验室检查。③结果航海期船员人均热能摄入量为１３．７４ＭＪ／ｄ，蛋白质１０８．３ｇ／ｄ，维生素Ａ，Ｂ２，Ｃ和钙摄入量不足。白细胞抗坏血酸含量和红细胞核黄素含量分别为１．４１±０．６８ｍｇ／１００ｇ和１３９．１±６５．３μｇ／Ｌ，都低于正常值标准。４ｈ尿负荷试验，维生素Ｂ１，Ｂ２，Ｃ和尼克酸不足人数分别为３１．３％，４２．２％，７８．９％和５．６％．船员维生素Ｃ和Ｂ２缺乏症发生人数为５１．２％和３７．２％．④结论远洋船员航海期食物结构不合理，膳食不平衡，身体营养状况较差。     

From the Cover: PNAS Plus: Climate change,pink salmon,and the nexus between bottom-up and top-down forcing in the subarctic Pacific Ocean and Bering Sea

Climate change in the last century was associated with spectacular growth of many wild Pacific salmon stocks in the North Pacific Ocean and Bering Sea, apparently through bottom-up forcing linking meteorology to ocean physics, water temperature, and plankton production. One species in particular, pink salmon, became so numerous by the 1990s that they began to dominate other species of salmon for prey resources and to exert top-down control in the open ocean ecosystem. Information from long-term monitoring of seabirds in the Aleutian Islands and Bering Sea reveals that the sphere of influence of pink salmon is much larger than previously known. Seabirds, pink salmon, other species of salmon, and by extension other higher-order predators, are tightly linked ecologically and must be included in international management and conservation policies for sustaining all species that compete for common, finite resource pools. These data further emphasize that the unique 2-y cycle in abundance of pink salmon drives interannual shifts between two alternate states of a complex marine ecosystem.Predator control of community structure and ecosystem function became a tenet of intertidal and nearshore marine ecology following early studies of Paine and others (1–3), yet with few exceptions (4, 5), until more recent times the idea has been less well appreciated for open oceans. Growing attention now is being paid to the overexploitation of pelagic species, particularly those at higher trophic levels currently and in the past, and effects on ocean ecosystems of the loss, or development, of top-down forcing (6–12).The prevailing view has long held that most biological change in ocean ecosystems, apart from human exploitation, is driven from the bottom up (13–16). One striking example that has been linked to bottom-up processes driven by climate change is the burgeoning abundance of wild Pacific salmon (Oncorhynchus spp.), and in particular pink salmon (Oncorhynchus gorbuscha), in the subarctic North Pacific Ocean and Bering Sea (SNPO/BS). Underpinning the notion initially were studies that found (i) strong coherence between decadal patterns in the Aleutian Low pressure system, which exerts a large influence over climate in the North Pacific Ocean, and patterns in salmon production across a broad region of the SNPO/BS (17, 18); (ii) decadal patterns in primary production that could be explained by the effect of the Aleutian Low pressure system on basin scale wind fields (19); and (iii) decadal patterns in zooplankton, squid, and pelagic fish production that also were correlated with meteorological forcing over the North Pacific Ocean and consistent with patterns in primary production (20). Thus, the general explanation for waxing and waning abundances of salmon over the record in the 20th century was that physical forcing by shifts in the strength and position of the Aleutian Low altered winds, ocean temperatures, and primary and secondary production to the benefit or detriment of salmon. A decadal scale oscillation in the Aleutian Low, now often referred to as the Pacific Decadal Oscillation (PDO) (21), has been linked to numerous physical and biological variability in the SNPO/BS in addition to salmon abundance (21–23).It was subsequently shown that salmon population responses and their relation to the PDO were out of phase between Alaska and the northwest coast of North America during much of the 20th century (24); that warm anomalies in coastal temperatures were associated with increased survival of salmon in Alaska; and that regional-scale variability in ocean temperature was a better predictor of salmon survival than large, basin-scale variability characterized by the PDO (25). A recent analysis from around the rim of the North Pacific Ocean found regional covariance in abundance of pink salmon, chum salmon (Oncorhynchus keta), and sockeye salmon (Oncorhynchus nerka) associated with the Aleutian Low, and with smaller scale spatially coherent, but regionally distinct, patterns in climate (26).Water temperature can be important to the early growth and survival of pink salmon fry directly by its effect on physiology and indirectly by its effect on the timing and development of zooplankton prey stocks in nursery areas, which commonly is advanced and greater in warmer years than in cooler years. In cooler springs, fry grow more slowly and a greater number die both from lack of food and from an increased susceptibility to predators (27, 28). For example, a conceptual model for Prince William Sound, Alaska, holds that, in years of abundant spring zooplankton, fry grow faster and remain longer in the shelter of inshore nurseries where they are protected from walleye pollock (Theragra chalcogramma) and Pacific herring (Clupea pallasii), two chief predators that remain offshore feeding primarily on swarms of large calanoid copepods and other macrozooplankton. In cooler years of lower zooplankton biomass inshore, fry grow more slowly, move offshore earlier, and suffer higher predation by pollock and herring due to spatial overlap, smaller size, and less alternative prey for those two predators (28).Although the relationship between climate and pink salmon survival is likely complex, fluctuations in abundance appear to be modulated in large measure directly and indirectly by the thermal environment in which a stock lives. Such a fundamentally bottom-up explanation is bolstered by observations of high growth and survival rates of pink salmon during the period of warmer ocean temperatures and population increase (29, 30), and at this time provides a more parsimonious explanation for population dynamics than would explanations invoking strictly top-down control across such a broad region. Now, however, several lines of evidence indicate that pink salmon themselves are having a large top-down influence on other salmon species, other upper trophic level pelagic species, plankton standing stocks, and by inference, the functioning of the open-ocean ecosystem in the SNPO/BS.     

Iron colloids dominate sedimentary supply to the ocean interior

Dissolution of marine sediment is a key source of dissolved iron (Fe) that regulates the ocean carbon cycle. Currently, our prevailing understanding, encapsulated in ocean models, focuses on low-oxygen reductive supply mechanisms and neglects the emerging evidence from iron isotopes in seawater and sediment porewaters for additional nonreductive dissolution processes. Here, we combine measurements of Fe colloids and dissolved δ⁵⁶Fe in shallow porewaters spanning the full depth of the South Atlantic Ocean to demonstrate that it is lithogenic colloid production that fuels sedimentary iron supply away from low-oxygen systems. Iron colloids are ubiquitous in these oxic ocean sediment porewaters and account for the lithogenic isotope signature of dissolved Fe (δ⁵⁶Fe = +0.07 ± 0.07‰) within and between ocean basins. Isotope model experiments demonstrate that only lithogenic weathering in both oxic and nitrogenous zones, rather than precipitation or ligand complexation of reduced Fe species, can account for the production of these porewater Fe colloids. The broader covariance between colloidal Fe and organic carbon (OC) abundance suggests that sorption of OC may control the nanoscale stability of Fe minerals by inhibiting the loss of Fe(oxyhydr)oxides to more crystalline minerals in the sediment. Oxic ocean sediments can therefore generate a large exchangeable reservoir of organo-mineral Fe colloids at the sediment water interface (a “rusty source”) that dominates the benthic supply of dissolved Fe to the ocean interior, alongside reductive supply pathways from shallower continental margins.

Sediments undergo early diagenetic transformations that are understood to provide an important source of dissolved iron (dFe) to the ocean that is used to fuel primary production and secondary food webs, fix nitrogen, and support the air–sea transfer of carbon dioxide (1, 2). Nevertheless, fundamental questions remain concerning the magnitude of dFe released from ocean sediments and the mechanisms through which this supply may be moderated. Such uncertainty is most acute in oxic and deep-water regions, which bear the fewest observations, but represent the largest area of the ocean sediment–water interface (3). Here, comparatively small sedimentary releases of dFe have the cumulative potential to enhance the dFe inventory of the deep ocean and—in so far as it connects with surface water—relieve iron deficiency for phytoplankton. Porewaters in these deep-water regions maintain a persistently oxic and/or nitrogenous state adjacent to bottom waters that is largely unexamined for its role in the marine iron cycle. These gaps in knowledge hinder our ability to make more accurate simulations of the carbon cycle in ocean biogeochemical models (4).Two principle processes are thought to be driving Fe dissolution from sediments that underpin the magnitude and variability of dFe inputs to the ocean. The first is a reductive-dissolution (RD) process, which demonstrably occurs during early diagenetic oxidation of organic carbon (OC) and produces high abundances of reduced, soluble, and isotopically light Fe in ferruginous porewaters, generally beneath the Fe-oxidizing fronts of nitrous oxides and oxygen (5–7). The second is a nonreductive-dissolution (NRD) process to account for the comparatively unfractionated or heavy isotope compositions of dFe attributed to sedimentary inputs in some oxygenated regions of the open ocean (8) and in the oxic zones of marine sediment porewaters (9), but the mechanisms governing so-called NRD in oxic sediments are unclear.RD of Fe is coupled to OC oxidation and is widely observed in shallow porewater in sediments with high-oxygen consumption rates, under productive shelf seas, near zones of upwelling, and overlain by oxygen-depleted seawater (10). Low seawater oxygen content serves to enhance the efflux of reduced and soluble Fe (sFe, filtered <0.02 µm) from ferruginous porewaters and enables sFe(II) to propagate further in the water column (11–14). Subsequently, without sufficient chelation by organic ligands sFe(II) will be lost to oxidative precipitation (7, 15, 16), scavenging (12), and sedimentation in deeper water (16, 17). Sedimentary RD provides a key component of the ocean’s dFe inventory that is most pronounced in the upper ocean (1, 10, 11, 13). It is also the only mechanism by which most ocean biogeochemical models simulate the sedimentary release of dFe (4), since model parameterizations rely on empirical relationships between dFe fluxes, OC oxidation rates, bottom water oxygen contents, and/or water depth (1, 11, 18, 19).NRD is a term previously used to describe a sedimentary source of isotopically heavy dFe to the water column (8) and has since been used to describe the presence of lithogenic isotope compositions observed in oxidizing zones from some deep ocean sediment porewaters (9). Similar observations have become commonplace in the ocean interior (20–23), such that nonreductive sedimentary processes appear to be important for the ocean’s dFe inventory. However, the detection of lithogenic dFe isotope signatures in porewaters (6, 9), within western North Atlantic benthic nepheloid layers, and in the water column far from sediment sources have been difficult to explain (24). The role played by this additional source of dFe is not yet included in global ocean models.Based on the very low solubility of silicate minerals and Fe(III) oxides in circumneutral pH and oxygenated seawater, NRD ought to be incapable of sustaining a benthic flux of dFe to the ocean without significant chelation by organic ligands (25). Because of a strong isotope fractionation effect, however, ligand complexation of Fe would produce a much heavier Fe isotope signal in the ocean (26), which is at odds with the isotopic evidence for NRD (20–23). To reconcile these differences between NRD theories and dFe isotope observations, we need to consider any physicochemical partitioning within the dFe pool. The abundance and isotope composition of dFe (<0.2 µm) may reflect variable contributions of mineral or organo-mineral Fe colloids (cFe, 0.02 to 0.2 µm) in addition to any ligand-bound Fe and sFe(II/III) species (<0.02 µm) in the ocean (23, 27). Such components of the dFe pool are often unaccounted for and have been neglected in previous studies reporting the occurrence of sedimentary NRD in the water column. However, sizable concentrations of cFe (10¹ µmoles ⋅ L⁻¹) have been observed in oxic-nitrogenous porewaters from deep ocean turbidites of the Southern Ocean, where dFe isotope compositions also matched the solid phase inputs from ocean island basalt. Whether these colloids were formed in situ through organic complexation and/or as secondary minerals from either reductive or nonreductive processes was unresolved. A comparison to fresh tephra layers in the Caribbean Sea showed that ocean island basalt weathering and production of nanoscale ferrihydrite or Fe-bearing smectite clays were thermodynamically plausible explanations for cFe in the Southern Ocean porewaters (28). Recently, Klar et al. (7) looked for Fe colloids in porewaters from a shallow shelf sediment, but found few if any, and that the porewaters were dominated by light dFe isotope signatures and sFe(II) attributable to RD by bacteria. Previous studies have not resolved where or why cFe occurs in sediment porewaters of the continental shelf–slope–basin transition or the extent to which they may influence the inventory and isotope composition of dFe input to the ocean (20, 22). These lessons need to be learned by examining the soluble and colloidal partitioning of dFe in porewaters and comparing them to dFe isotope signatures from a wider range of sedimentary carbon and oxygen regimes in the ocean environment.Without appropriate simulation of this dFe source, ocean biogeochemical models will fail to represent spatial patterns in dFe flux from the seafloor, the response of these fluxes to changing ocean environments, and their consequences for ocean biogeochemistry. Confounding this issue is the omitted role of advective transport mechanisms, internal waves, and benthic boundary layers that will facilitate exchanges between oxic sediments and the ocean interior (3, 29, 30). To make progress on this important issue, we require new understanding on the mechanisms by which Fe dissolves and is supplied to the ocean by oxic sediments.Herein, we present findings from surface sediment cores from sites that span the depth and breadth of the Southwest Atlantic Ocean. The UK-led GEOTRACES expedition, GA10W, recovered porewaters in 2011 from the Uruguayan continental shelf and slope, Argentine abyssal floor, and Mid-Atlantic Ridge (SI Appendix, Table S1). We report porewater dFe isotope compositions and further evidence of the physicochemical partitioning of dFe between soluble and colloidal size fractions (where cFe = dFe−sFe) at selected locations and depths where porewater inventories of Fe were sufficient to permit these determinations. We apply principles of isotope fractionation and mass balance across the dissolved and soluble size classes to test hypothetical controls on the dFe pool in these porewaters. Our study reveals that oxidizing zones of marine sediments are important regions of nonreductive cFe production derived from lithogenic material, which ultimately determine the dFe inventory and isotope composition supplied to the deep ocean.     

From the Cover: Dynamic patterns and ecological impacts of declining ocean pH in a high-resolution multi-year dataset

Increasing global concentrations of atmospheric CO₂ are predicted to decrease ocean pH, with potentially severe impacts on marine food webs, but empirical data documenting ocean pH over time are limited. In a high-resolution dataset spanning 8 years, pH at a north-temperate coastal site declined with increasing atmospheric CO₂ levels and varied substantially in response to biological processes and physical conditions that fluctuate over multiple time scales. Applying a method to link environmental change to species dynamics via multispecies Markov chain models reveals strong links between in situ benthic species dynamics and variation in ocean pH, with calcareous species generally performing more poorly than noncalcareous species in years with low pH. The models project the long-term consequences of these dynamic changes, which predict substantial shifts in the species dominating the habitat as a consequence of both direct effects of reduced calcification and indirect effects arising from the web of species interactions. Our results indicate that pH decline is proceeding at a more rapid rate than previously predicted in some areas, and that this decline has ecological consequences for near shore benthic ecosystems.     

Association between prenatal dietary methyl mercury exposure and developmental outcomes on acquisition of articulatory-phonologic skills in children in the Republic of Seychelles

Methyl mercury (MeHg) is a neurotoxicant that with sufficient exposure can seriously impair the central nervous system and cause mental retardation, cerebral palsy, and neuromotor dysfunction. The level of exposure needed to adversely affect the nervous system is unknown. Human exposure to low levels of MeHg is common from consumption of fish. We examined the relationship between MeHg exposure and development of articulatory-phonologic speech skills in children whose mothers consumed a diet high in fish during pregnancy to determine whether any adverse associations could be detected. A total of 544 children from the Republic of Seychelles were given a speech assessment when they were 66 months of age. Exposure level was determined by measuring MeHg in maternal hair growing during pregnancy. No adverse associations between articulatory- phonologic speech skills and prenatal MeHg exposure were detected. The findings of this investigation are compatible with previous developmental assessments of Seychellois children that have indicated no adverse effects of prenatal MeHg exposure from fish consumption.     

Acute CO2 tolerance during the early developmental stages of four marine teleosts

Ocean sequestration of CO2 is proposed as a possible measure to mitigate climate changes caused by increasing atmospheric concentrations of the gas, but its impact on the marine ecosystem is unknown. We investigated the acute lethal effect of CO2 during the early developmental stages of four marine teleosts: red sea bream (Pagrus major), Japanese whiting (Sillago japonica), Japanese flounder (Paralichthys olivaceus), and eastern little tuna (Euthynnus affinis). The percentages of larvae that hatched and survived were not affected by exposure to water with a PCO2 of 1.0 kPa (= 7.5 mmHg) within 24 h. Median lethal PCO2 values for a 360-min exposure were 1.4 kPa (cleavage), 5.1 kPa (embryo), 7.3 kPa (preflexion), 4.2 kPa (flexion), 4.6 kPa (postflexion), and 2.5 kPa (juvenile) for red sea bream; 2.4 kPa (cleavage), 4.9 kPa (embryo), 5.9 kPa (preflexion), 6.1 kPa (flexion), 4.1 kPa (postflexion), and 2.7 kPa (juvenile) for Japanese whiting; 2.8 kPa (cleavage) and > 7.0 kPa (young) for Japanese flounder; and 11.8 kPa (cleavage) for eastern little tuna. Red sea bream and Japanese whiting of all ontogenetic stages had similar susceptibilities to CO2: the most susceptible stages were cleavage and juvenile, whereas the most tolerant stages were preflexion and flexion.     

在入境船舶上采获蠓科一新种斑腹阿蠓(双翅目:蠓科)

目的了解入境国际航行船舶携带输入性蠓类的情况。方法在锚地入境国际航行船舶的生活区内采集蠓类,进行计数和分类鉴定。结果2007年1月24日在自澳大利亚经印度至秦皇岛的一艘入境船舶上采获35只输入性蠓类,经鉴定隶属于5个属,其中发现阿蠓属一新种,斑腹阿蠓(Alluaudomyia maculiabdominis sp.nov.)。结论再次证明入境国际航行船舶可携带多种输入性蠓类的事实。     

Role of macroscopic particles in deep-sea oxygen consumption

Macroscopic particles (>500 μm), including marine snow, large migrating zooplankton, and their fast-sinking fecal pellets, represent primary vehicles of organic carbon flux from the surface to the deep sea. In contrast, freely suspended microscopic particles such as bacteria and protists do not sink, and they contribute the largest portion of metabolism in the upper ocean. In bathy- and abyssopelagic layers of the ocean (2,000–6,000 m), however, microscopic particles may not dominate oxygen consumption. In a section across the tropical Atlantic, we show that macroscopic particle peaks occurred frequently in the deep sea, whereas microscopic particles were barely detectable. In 10 of 17 deep-sea profiles (>2,000 m depth), macroscopic particle abundances were more strongly cross-correlated with oxygen deficits than microscopic particles, suggesting that biomass bound to large particles dominates overall deep-sea metabolism.