Degree of purification of a chemical epidemic typhus vaccine of the heterogeneous ballast proteins

The degree of purification of chemical typhus vaccine from the ballast proteins of the substrate has been studied by chemical and immunochemical methods. The analysis of 11 production batches of the vaccine and a number of model preparations has revealed that chemical typhus vaccine is completely free from nonprotein nitrogen-containing components and, to a considerable extent, purified from ballast protein, its concentration being 0.033-0.242 mg per vaccination dose, and also possesses a high specific activity (198-1454 antigenic units per mg of protein. Ballast proteins include at least 5 egg antigens. The concentration of one of them varies between 0 and 5 micrograms per dose. A number of recommendations is made; their realization will make it possible to increase the degree of purification of chemical typhus vaccine.     

A biological survey of ballast water in container ships entering Hong Kong

The role of ballast water in the introduction of exotic species has recently received extensive attention. The aim of this study is to assess the importance of ballast water discharge as a vector for the introduction of exotic species into Hong Kong waters. Twelve ballast water samples were collected from 5 container ships entering Hong Kong between June1994 and October 1995. The ballast water originated from ports on both sides of the Pacific Ocean. At least 81 species from 8 animal phyla and 5 protist phyla were found. Most of the major marine taxonomic groups were represented and many planktonic larval stages were included. Species richness in the ballast tanks decreased with the age of ballast water. Copepoda was the most diverse and abundant taxonomic group. The density of calanoid and cyclopoid copepods decreased with the age of ballast water, but that of harpacticoid copepods did not change significantly with time. Bivalve, crustacean, polychaete and ascidian larvae from ballast water samples were observed to settle in laboratory culture tanks. The mussel Mytilopsis sallei which was introduced to Hong Kong in 1980, was one of the bivalves that settled readily. Results of this study indicate that ballast water can be a major source for the introduction of exotic species to Hong Kong waters. Regulatory guidelines on the discharge of ballast water should be established. This revised version was published online in August 2006 with corrections to the Cover Date.     

A highly uniform UV transillumination imaging system for quantitative analysis of nucleic acids and proteins

The digital fluorescent imaging for documentation and analysis of gel electrophoretic separations of nucleic acids and proteins is widely used in quantitative biology. Most fluorescent stains used in postelectrophoretic analysis of proteins and nucleic acids have significant excitation peaks with UV light (300-365 nm), making midrange UV (UV-B) as the excitation source of choice. However, coupling quantitative CCD imaging with UV is difficult due to lack of uniformity found in typical UV transilluminators. The apparent amount of those macromolecules depends on the position of the gel band on the imaging surface of the transilluminator. Here, we report the development and validation of a highly uniform UV transillumination system. Using a novel high density lighting system containing a single lamp formed into a high density grid, an electronic ballast, a phosphor coating, and a bandpass filter to convert 254 nm light produced to 300-340 nm, uniformity of 80% CV observed in typical UV transilluminators. This system has been used for the quantitative analysis of electrophoretically separated nucleic acids and proteins (CV相似文献   

Optimizing methods to estimate zooplankton concentration based on generalized patterns of patchiness inside ballast tanks and ballast water discharges

Zooplankton populations are spatially heterogeneous in nature and inside ship ballast tanks. Sampling methods should take heterogeneity into account, particularly when estimating quantitative variables such as abundance or concentration. It is particularly important to generate unbiased estimates of zooplankton concentration in ballast water when assessing compliance with new international ballast water discharge standards. We measured spatial heterogeneity of zooplankton within ballast water using three sampling methodologies. In‐tank pump samples were collected at fixed depths within the vertical part of the ballast tank (side tank). Vertical net‐haul samples were collected from the upper portion of the tank as a depth‐integrated and historically relevant method. In‐line, time‐integrated samples were collected during ballast discharge by an isokinetic sample probe, likely representing the double bottom part of the ballast tank. The bias and precision associated with each sampling method were evaluated in reference to the estimated average abundance of the entire ballast tank, which was modeled from the data collected by all methods. In‐tank pump samples provided robust evidence for vertical stratification of zooplankton concentration in the side tank. A consistent trend was also observed for in‐line discharge samples, with zooplankton concentration decreasing through time as the ballast tank is being discharged. Sample representativeness, as compared to the tank average, varied depending on the depth or tank volume discharged. In‐line discharge samples provided the least biased and most precise estimate of average tank abundance (having lowest mean squared error) when collected during the time frame of 20%–60% of the tank volume being discharged. Results were consistent across five trips despite differences in ballast water source, season, and age.     

In situ hatching of invertebrate diapausing eggs from ships' ballast sediment

Ships that enter the Great Lakes laden with cargo carry only residual ballast water and sediment in ballast tanks. These ships are designated ‘no ballast on board’ (NOBOB) and constitute > 90% of inbound traffic. We conducted in situ experiments using emergence traps to assess the viability and the introduction potential of invertebrate diapausing stages present in ships’ ballast sediment. All trials commenced while vessels operated on the lower lakes (Erie, Ontario) and were completed 6–11 days later at ports on the upper lakes (Michigan, Lake Superior). Eight trials were conducted on four ships using five different ballast sediments. Hatching was observed on every ship, although not from all sediments on all ships. Overall hatch rates were very low (0.5 individuals per 500 g sediment), typically involving activation of < 0.05% of total eggs present. Five species of rotifers and copepod nauplii were hatched from ballast sediments, although only one or two species typically hatched from any one sediment. Results of this study indicate that hatching of diapausing eggs contained in ballast sediment of NOBOB ships poses a relatively low risk of invasion to the Great Lakes. However, as reproduction may occur in tanks, and non‐indigenous species may be involved in numerous introduction events, the risk posed by this vector is small but potentially important. While dormancy is a characteristic enabling enhanced survival during transportation in ballast tanks, it becomes a hindrance for introduction.     

Ground reaction forces during human locomotion on railroad ballast

Locomotion over ballast surfaces provides a unique situation for investigating the biomechanics of gait. Although much research has focused on level and sloped walking on a smooth, firm surface in order to understand the common kinematic and kinetic variables associated with human locomotion, the literature currently provides few if any discussions regarding the dynamics of locomotion on surfaces that are either rocky or uneven. The purpose of this study was to investigate a method for using force plates to measure the ground reaction forces (GRFs) during gait on ballast. Ballast is a construction aggregate of unsymmetrical rock used in industry for the purpose of forming track bed on which railway ties are laid or in yards where railroad cars are stored. It is used to facilitate the drainage of water and to create even running surfaces. To construct the experimental ballast surfaces, 31.75 mm (1 1/4 in.) marble ballast at depths of approximately 63.5 mm (2.5 in.) or 101.6 mm (4 in.) were spread over a carpeted vinyl tile walkway specially designed for gait studies. GRF magnitudes and time histories from a force plate were collected under normal smooth surface and under both ballast surface conditions for five subjects. GRF magnitudes and time histories during smooth surface walking were similar to GRF magnitudes and time histories from the two ballast surface conditions. The data presented here demonstrate the feasibility of using a force plate system to expand the scope of biomechanical analyses of locomotion on ballast surfaces.     

Does saltwater flushing reduce viability of diapausing eggs in ship ballast sediment?

Flushing of ballast tanks with seawater has been proposed to reduce the risk of invasion associated with residual ballast in 'no ballast on board' ships. The efficacy of this procedure, however, has not been determined. Using diapausing eggs isolated from ballast sediments — as well as from Lake Erie sediment — this study investigated the impact of salinity (0, 8 and 35‰) and temperature (10, 20 and 30 °C) on the cumulative abundance and species richness of hatched zooplankton taxa. The rate and amount of hatching varied dramatically between sediments and across salinity–temperature regimes. Although exposure to saline water inhibited emergence of freshwater taxa during the exposure phase of all trials, mixed results were evident after diapausing eggs were returned to freshwater. The efficacy of salinity as a ballast treatment method was temperature dependent, although the direction of the effect was case-specific. Exposure of eggs to saline water was less effective at 10 and 30 °C than at 20 °C. Although flushing ballast tanks with open ocean water is expected to significantly reduce the number of active invertebrates living in residual ballast water (a potentially larger source of invaders), our results indicate that the most effective treatment conditions for reduction of diapausing egg viability is 8‰ salinity at 20 °C.     

Diatom survivorship in ballast water during trans-Pacific crossings

Ship ballast water is believed to be responsible for global dispersal of alien biota; mid-ocean ballast water exchange is most commonly used to mitigate this process. Diatoms are among the most abundant biotic-component in ballast water, yet their invasive biology is poorly understood. To test effectiveness of MOE we examined diatom species composition and cell density in two sets of samples. First, we examined samples collected daily during one 24 days long trans-Pacific crossing in tanks with and without ballast exchanged. Second, we used samples from 23 trans oceanic vessels arriving at Vancouver harbour where diatoms were collected on arrival. Up to 86,429 live diatom cells/l were found in the tanks, ~50% of the samples share up to eight species consistently present. Cell densities and species richness declined over time and with replacement of coastal ballast water by mid-oceanic water. In both data sets diatoms survive in the tanks for as long as 33 days despite ballast exchange.     

Proteolysis of horse blood serum proteins at various stages of antitoxic sera production by the Diaferm-3 method

When preparing antitoxic sera by the method "Diaferm-3", it was found that proteolysis of the horse blood serum occurs not only at the fermentation step (pepsin treatment at the enzyme-substrate ratio of 1/10, t 20-23 degrees for an hour at pH 3.3 and for the next hour at pH 4.2), but also at the heat treatment step (45 min at pH 4.3, t 56-58 degrees in the presence of ammonium sulfate at a concentration of 140-145 g/l). At the fermentation step immunoglobulins do not split completely into F(ab')2 fragments, 40% of the antitoxic activity being lost at this step. Some ballast proteins--albumin, fibrinogen, etc.--quickly split up into peptides, while other proteins undergo only limited proteolysis. Structural destabilization of serum proteins during thermodenaturing is favorable for the pepsin action and provides for a complete conversion of immunoglobulins to F(ab')2 and Fab' fragments. At this step about 15% of the antitoxic activity is additionally lost. Thus, proteolysis at the thermodenaturation step is an essential part of the "Diaferm-3" process.     

Functional significance of bone ballastin in the evolution of buoyancy control strategies by aquatic tetrapods

The primary function of pachyostosis, pachyosteo‐sclerosis, and osteosclerosis may be to act as ballast, not so much (as previously suggested) to neutralise the buoyancy of existing lungs, but to allow enlargement of the lungs. Enlarged lungs cause an animal to lose buoyancy more rapidly with depth. They also provide a larger oxygen store. These features are useful for slow swimmers and shallow divers, such as feeders on benthic plants and invertebrates. Examples are sirenians, primitive sauropterygians ("not‐hosaurs"), placodonts, and the sea otter Enhydra. These last two show convergent evolution of adaptations to feeding on hard‐shelled invertebrate prey in shallow water. Mesosaurids are problematical. Bone ballast uses body mass and volume less efficiently than other buoyancy control strategies. Theoretical analysis predicts that bone ballast should not occur in semiaquatic forms, fast swimmers or deep divers. It does not usually occur in such organisms. Marine iguanas of the Galápagos, desmostylians, and the aquatic sloth Thalassocnus are all littoral feeders and all lack bone ballast as predicted. Plesiosaurs adopted varied strategies: some used bone ballast, and others used gastroliths. Biomechanical considerations lead to the prediction that a new marine tetrapod clade will typically evolve bone ballast as part of its adaptation to life in water. Slow swimmers and grazers on sessile food, like sirenians and placodonts, develop it more strongly, but active predators like ichthyosaurs and cetaceans secondarily lose this character.     

Transport of the harmful bloom alga Aureococcus anophagefferens by oceangoing ships and coastal boats

It is well established that cyst-forming phytoplankton species are transported in ships' ballast tanks. However, there is increasing evidence that other phytoplankton species which do not encyst are also capable of surviving ballast transit. These species have alternative modes of nutrition (hetero- or mixotrophy) and/or are able to survive long-term darkness. In our studies of no-ballast-on-board vessels arriving in the Great Lakes, we tested for the presence of the harmful algal bloom species Aureococcus anophagefferens (brown tide) in residual (i.e., unpumpable) ballast water using methods based on the PCR. During 2001, the brown tide organism was detected in 7 of 18 ballast water tanks in commercial ships following transit from foreign ports. Furthermore, it was detected after 10 days of ballast tank confinement during a vessel transit in the Great Lakes, a significant result given the large disparity between the salinity tolerance for active growth of Aureococcus (>22 ppt) and the low salinity of the residual ballast water (approximately 2 ppt). We also investigated the potential for smaller, recreational vessels to transport and distribute Aureococcus. During the summer of 2002, 11 trailered boats from the inland bays of Delaware and coastal bays of Maryland were sampled. Brown tide was detected in the bilge water in the bottoms of eight boats, as well as in one live-well sample. Commercial ships and small recreational boats are therefore implicated as potential vectors for long-distance transport and local-scale dispersal of Aureococcus.     

Transport of the Harmful Bloom Alga Aureococcus anophagefferens by Oceangoing Ships and Coastal Boats

It is well established that cyst-forming phytoplankton species are transported in ships' ballast tanks. However, there is increasing evidence that other phytoplankton species which do not encyst are also capable of surviving ballast transit. These species have alternative modes of nutrition (hetero- or mixotrophy) and/or are able to survive long-term darkness. In our studies of no-ballast-on-board vessels arriving in the Great Lakes, we tested for the presence of the harmful algal bloom species Aureococcus anophagefferens (brown tide) in residual (i.e., unpumpable) ballast water using methods based on the PCR. During 2001, the brown tide organism was detected in 7 of 18 ballast water tanks in commercial ships following transit from foreign ports. Furthermore, it was detected after 10 days of ballast tank confinement during a vessel transit in the Great Lakes, a significant result given the large disparity between the salinity tolerance for active growth of Aureococcus (>22 ppt) and the low salinity of the residual ballast water (~2 ppt). We also investigated the potential for smaller, recreational vessels to transport and distribute Aureococcus. During the summer of 2002, 11 trailered boats from the inland bays of Delaware and coastal bays of Maryland were sampled. Brown tide was detected in the bilge water in the bottoms of eight boats, as well as in one live-well sample. Commercial ships and small recreational boats are therefore implicated as potential vectors for long-distance transport and local-scale dispersal of Aureococcus.     

Optimization of the refolding of recombinant human granulocyte-macrophage colony-stimulating factor immobilized on affinity sorbent

A method for the production and purification of biologically active recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF), expressed in Escherichia coli, has been developed. Washing of an inclusion body fraction which allows the removal of numerous ballast proteins and on-column refolding of rhGM-CSF are specific characteristics of the method. The refolding efficiency reached 70%; the purity of the preparation constituted 95%. The biological activity was similar to those of other recombinant hGM-CSF analogs.     

Invasion Pressure to a Ballast-flooded Estuary and an Assessment of Inoculant Survival

The relationships between invasion pressure, post-transport inoculant survival, and regional susceptibility to invasion are poorly understood. In marine ecosystems, the movement and release of ballast water from ocean-going ships provides a model system by which to examine the interplay among these factors. One of the largest estuaries in North America, the Chesapeake Bay, receives tremendous amounts of foreign ballast water annually and thus should be at high invasion risk. To date, however, few introductions in Chesapeake Bay have been attributed to ballast release. To understand better the dynamics of this invasion process, we (1) characterized and quantified the biota arriving to Chesapeake Bay in foreign ballast water, (2) compared temperatures and salinities of ballast water and harbor water in upper Chesapeake Bay, and (3) tested experimentally survival of organisms collected from ballast water in temperatures and salinities characteristic of the region. From 1993 to 1994, we sampled planktonic and benthic organisms from 60 foreign vessels arriving to Chesapeake Bay. Our data show that the estuary is being inoculated by a diverse assemblage of aquatic organisms from around the world. Furthermore, the short transit time (15d) for most vessels ensured that substantial numbers of larval and post-larval organisms were being deballasted alive. Most of the ballast water discharged into the upper Chesapeake Bay, however, was significantly higher in salinity (>20) than that of the receiving harbor. In laboratory tolerance experiments, ballast water organisms perished under such conditions. Thus, a mismatch in physical conditions between donor and receiver regions may explain the dearth of invasions in the upper Bay. It is likely that the lower Chesapeake Bay, which is more saline, remains at higher risk to ballast water invasion. Recognition of such intraregional differences should allow more focused predictions for monitoring and management.     

Recent mass invasion of the North American Great Lakes by Ponto-Caspian species

The North American Great Lakes have been invaded and dramatically altered by more than 145 alien species. Many invasions have occurred during the past few decades because of the release of Eurasian ballast water from transoceanic ships. Current regulations require ships to exchange foreign ballast with highly saline water before entering the Great Lakes; this procedure should prevent colonization by strictly freshwater species, but species with broad salinity tolerance might survive transport in exchanged water. A recent series of invasions by euryhaline organisms from the Black and Caspian Seas region signals a new phase in the transformation of the Great Lakes - one that supports the concept of an 'invasional meltdown'.     

Reflections on the ballast water dispersal—harmful algal bloom paradigm

The ballast water dispersal—HAB paradigm, increasingly invoked circumstantially to explain puzzling and unaccountable HAB species outbreaks when lacking the multiple tests of confirmation recommended by Bolch and de Salas (2007), is evaluated. The types and examples of natural dispersions and taxon cycles are compared to exotic species bloom behavior linked to ballast water vectoring. The regional spreading, bloom behavior and disjunct distributions of the brown tide pelagophyte Aureococcus anophagefferens and the toxic dinoflagellate Gymnodinium catenatum, attributed to ballast water vectoring, are used as representative examples to evaluate the general application of the ballast water—HAB paradigm and associated interpretative problems. Human-aided emigration has a seeding and colonization ecology that differs from bloom ecology. For self-sustaining blooms to occur, these two ecologies must be accommodated by habitat growth conditions. The three stages that a non-native species must pass through (pioneering, persistence, community entry) to achieve colonization, community maintenance, and to bloom, and the niche-related factors and role of habitat disturbance are discussed. The relevance of cryptic occurrences, cyst deposits, dormancy periods and bloom rhythms of HAB species to their blooms attributed to ballast water-assisted introductions is also sketched. The different forms of HAB species rarity, their impact on the ballast water dispersal—HAB paradigm, and the dispersion and blooms of specialist and generalist HAB species are discussed. The remarkable novel and, often, monospecific blooms of dinoflagellate HAB species are being paralleled by similar eruptive bloom behavior cutting across phylogenetic lines, and being found also in raphidophytes, haptophytes, diatoms, silicoflagellates, etc. These blooms cannot be explained only as seeding events. An ecological release of ‘old barriers’ appears to be occurring generally at coastal bloom sites, i.e. something significant is happening ecologically and embedded within the ballast water—HAB paradigm. There may be a relationship between Life Form type [Smayda, T.J., Reynolds, C.S., 2001. Community assembly in marine phytoplankton: application of recent models to harmful dinoflagellate blooms. J. Plankton Res. 23, 447–461] and mode of expatriation; HAB dinoflagellate species commonly reported to produce ballast water-assisted toxic blooms invariably are members of cyst-producing Life Forms IV, V, VI. Ballast water vectoring of Life Forms I, II, III is rarely reported, even though many produce cysts, and where their novel introductions do occur they are more likely to be ichthyotoxic and vectored in shellfish stock consignments. The relevance of, and need to distinguish between morphospecies and their geographic/ribotype clades are discussed based on the Alexandrium tamarense/catenella/fundyense complex. Morphospecies-level ballast water dispersions are probably minor compared to the dispersal of the different ribotypes (toxic/non-toxic clades) making up HAB morphospecies; the redistribution and admixture of genotypes should be the focus. Ballast water-assisted expatriations impact the global occurrence of HABs through the direct transfer of previously absent species or introduction of genetic strains from the donor habitat that are ecologically favored over resident strains. The hybridization of species may be of potentially greater impact, resulting from the (1) mating of individuals from the donor and recipient habitats, or (2) through the interbreeding of strains introduced from two different donor sites into the recipient site, and whose progeny have greater ecological fitness than indigenous strains. Exceptional ecological changes of some sort appear to be occurring globally which, in combination with the genetically altered ecophysiological behavior of HAB species linked to ballast water dispersion and admixture, underpins the global HAB phenomenon. The impact of ballast water and shellfish transplantation on HABs and phytoplankton community ecology, generally, is considerably greater than the current focus on HAB species distributions, vectoring, and blooms. The methodological, investigative and conceptual potential of the ballast water—HAB paradigm should be exploited by developing a GEOHAB type intiative to advance quantification of global HAB ecology.     

Effects of temperature and salinity on survival of toxigenicVibrio cholerae O1 in seawater

In 1991 and 1992, the Latin American epidemic strain of Vibrio cholerae O1 was isolated from ballast water, bilge water, and sewage taken from cargo ships docked in Mobile Bay, Alabama. The findings raised questions regarding the organism's ability to survive long-term aboard ships and to withstand the exchange of ballast at sea. The effects of temperature (6, 18, and 30°C) and salinity (8, 16, and 32 ppt) on survival of V. cholerae O1 strains C6706 and C6707 and a ballast water isolate in sterile seawater were determined. The ballast water isolate, which had a D-value (number of days required to produce a 1 log₁₀ reduction in colony-forming units per milliliter) of 240 days at 18°C, 32 ppt salinity, had the longest survival time. The range of D-values was 36–240 days at 18°C, 60–120 days at 30°C, and 5–20 days at 6°C. In sterile seawater short-term survival was temperature dependent, whereas long-term survival was salinity dependent. In raw seawater, survival time of the ballast water isolate was reduced to 12–27 days, implying the existence of biological influences. As also shown in our previous work, the organism appeared to be able to survive for several months under relatively stable conditions in ballast water aboard ships; however, viability may be reduced to only a few weeks after the organism is introduced into estuarine or marine environments. Correspondence to: Susan A. McCarthy.     

Acclimation and introduction of hydrobionts ships’ ballast water organisms in the Port of Vladivostok

Work on the investigation of organisms of ballast water and sediments of ships sailing on Russia-Japan and Russia-China lines was started in the Port of Vladivostok for the first time for the Far East seas of Russia. In total, 145 taxa, 37 microalgal species, 24 holoplankton species, 22 meroplankton taxa, and 10 meiofauna groups were revealed, 24 species of microscopic mycelia fungi were attributed, and 28 morphologically distinct bacterial stains were isolated. Potentially toxic microalgal species were found: the dinoflagellates Dinophysis acuminate and Prorocentrum cordatum and the diatom Pseudo-nitzschia pungens. The tropical-subtropical copepod Pseudocalanus inopinus was recorded in ballast water. Polychaete larvae of the Polydora genus with an unusual morphology, which were not occurring in the Peter the Great Bay previously, were recorded as probable southern migrants from the coastal waters of the southwest coast of Honshu Island. Live larvae of the hermit crab Diogenes nitidimanus were revealed in ballast water, supporting the possibility of introduction of this species in the Peter the Great Bay. Based on an analysis of the total number of colony-forming units of heterotroph microorganisms (within the order of 10³–10⁴ cells/ml), the ballast water of ships sailing on the Russia-Japan line was characterized as moderately polluted. The detection of Escherichia coli strains, exceeding the standards quoted in the International Convention by three times or more, showed the potential danger of a mass bioinvasion. Conditionally pathogenic and toxinogenic mycelial fungi, which are able to induce mycoses and mycotoxicoses in invertebrates and fishes, were isolated from ballast water. It was determined that ballast water of the “rusty” type was poorly suited for the existence of zoo- and phytoplankton forms. In the case of the construction of an oil terminal in the Peter the Great Bay, a sharp increase of the introduction of exotic species via the ballast water and foulings of tankers is inevitable     

Flocculant interaction with native antibiotic solutions. The effect of flocculants on the quality indices of native solutions as dependent on a number of factors]

Flocculants had a significant effect on the characteristics of the fermentation broth filtrates of some antibiotics. They decreased the filtrate turbidity, concentration of the organic ballast, etc. The size of the floccules depended on a number of factors, including the fluocculant concentration, agitation rate, concentration of the dispersing phase in the initial filtrate. The optimal concentration of the flocculant was defined not only by the type of the antibiotic-producing organism but also by composition of the nutrient medium used for the biosynthesis. Floccculant treatment provided a significant increase in the quality of the fermentation broth filtrates with respect to the main parameters: levels of proteins, pigments, emulgation capacity.     

Effects of Ocean Acidification on the Ballast of Surface Aggregates Sinking through the Twilight Zone

The dissolution of CaCO₃ is one of the ways ocean acidification can, potentially, greatly affect the ballast of aggregates. A diminution of the ballast could reduce the settling speed of aggregates, resulting in a change in the carbon flux to the deep sea. This would mean lower amounts of more refractory organic matter reaching the ocean floor. This work aimed to determine the effect of ocean acidification on the ballast of sinking surface aggregates. Our hypothesis was that the decrease of pH will increase the dissolution of particulate inorganic carbon ballasting the aggregates, consequently reducing their settling velocity and increasing their residence time in the upper twilight zone. Using a new methodology for simulation of aggregate settling, our results suggest that future pCO₂ conditions can significantly change the ballast composition of sinking aggregates. The change in aggregate composition had an effect on the size distribution of the aggregates, with a shift to smaller aggregates. A change also occurred in the settling velocity of the particles, which would lead to a higher residence time in the water column, where they could be continuously degraded. In the environment, such an effect would result in a reduction of the carbon flux to the deep-sea. This reduction would impact those benthic communities, which rely on the vertical flow of carbon as primary source of energy.