Abstract. A global in situ dataset for validation of satellite products from the ESA Ocean Colour Climate Change Initiative (OC-CCI) is presented. This version of the compilation, with data starting in 1996, extends to 2025, which is important for the validation of recent algorithms and satellite products. The dataset comprises in situ observations of the following variables: spectral remote-sensing reflectance (rrs), chlorophyll-a concentration ("chla"; HPLC and fluorometric), spectral inherent optical properties (IOPs: algal pigment absorption "aph", detritus plus gelbstoff absorption "adg", and particle backscattering "bbp"), spectral diffuse attenuation coefficient (kd) and total suspended matter (tsm). Data were obtained from multiple archives acquired via open internet services, or from individual projects, acquired directly from data providers. Compared to the previous version (Valente et al., 2022) this release incorporates updates from existing sources and introduces data from 13 additional sources. Notably, AERONET-OC coverage has been significantly expanded (39 sites compared to 11 in v2022) and MOBY Platinum data have been included from 2024. Methodologies were implemented for homogenisation, quality control and merging of all data. Minimal changes were made to the original data, other than conversion to a standard format, elimination of some points after quality control and averaging of observations that were close in time and space. The harmonisation procedures also include the application of a bidirectional reflectance distribution function (BRDF) correction to "rrs". The result is a merged table available in text format. Overall, the dataset increased by ~115 %, reaching 319,183 rows, with each row representing a unique station in space and time (cf 148,432 rows in Valente et al., 2022). Records of chlaovera increased by ~31 % (82,543 to 107,922); "rrs" observations nearly doubled +94 % (68,641 → 133,325); IOPs showed substantial expansion, with aph increasing by ~150 % (4,265 to 10,655) and adg by 78 % (1,654 to 2,948). The most pronounced change was for bbp, which increased by ~10,258 % (792 to 82,033), while moderate increases were observed for kd (+30 %; 2,454 to 3,197) and "tsm" (+51 %; 1,546 to 2,334). Metadata of each in situ measurement (original source, cruise or experiment, principal investigator) are included in the final table. By making the metadata available, provenance is better documented, and it is also possible to analyse each set of data separately. The compiled data are available at (Salem et al., 2026).

Estimating phytoplankton community structure using diagnostic pigment biomarkers relies on chemotaxonomic tools like CHEMTAX and the mathematical improvements of the phytoclass R package. However, phytoclass requires programming experience that limits its accessibility to non-coders. We present phytoclassShiny, a free, open-source, offline R Shiny application that guides users through a linear, seven-step workflow - from high-performance liquid chromatography (HPLC) data import and quality control to simulated annealing optimisation and export - without requiring programming skills. Every session’s parameters, data-handling decisions, and results are recorded in a shareable configuration file and audit log, addressing current reporting gaps and supporting full reproducibility. We validated phytoclassShiny's phytoplankton community estimates against the native phytoclass package using a benchmark Southern Ocean dataset. Estimates agreed closely across seven of eight phytoplankton groups (R² ≥ 0.97), with one group showing marginally lower agreement (Pelagophytes, R² = 0.90). This minor variation was attributed to a disclosed difference in benchmark parameters rather than by any alteration of phytoclass's underlying mathematics. Repeated tests using a fixed random seed reproduced results exactly. phytoclassShiny therefore removes the programming burden of phytoclass analysis without any cost in accuracy. However, like all chemotaxonomic methods, successful analysis still relies on the user's foundational taxonomic and ecological knowledge of their study system. phytoclassShiny broadens access to pigment-based chemotaxonomy for researchers without programming experience, and, when used deliberately, can help newcomers build the very foundational experience that emergent phytoclass method requires.

Phytoplankton are critical to the Antarctic marine food web and associated biological carbon pump, yet long-term shifts in their community composition are poorly understood. Here, using a machine learning framework and combining pigment samples and environmental samples from austral summertime 1997-2023, we show declines in diatoms and increases in haptophytes and cryptophytes across much of Antarctica's continental shelf. These trends-which are linked to sea ice increases-reversed after 2016, with a rebound in diatoms and a large increase in cryptophytes, coinciding with the loss of sea ice. Significant changes (P < 0.05) across the 25-year dataset include diatom chlorophyll a (chl-a) declines of 0.32 mg chl-a m(-3) (similar to 33% of the climatology) and increases for haptophytes and cryptophytes of 0.08 and 0.23 mg chl-a m(-3), respectively. The long-term shifts in phytoplankton assemblages could reduce the dominance of the krill-centric food web and diminish the biologically mediated export of carbon to depth, with implications for the global-ocean carbon sink.

Southern Ocean phytoplankton form the base of the Antarctic food web, influencing higher trophic levels through biomass and community structure. We examined phytoplankton distribution and abundance in the Indian Sector of the Southern Ocean during austral summer as part a multidisciplinary ecosystem survey: Trends in Euphausiids off Mawson, Predators and Oceanography (TEMPO, 2021). Sampling covered six meridional transects from 55-80°E, and from 62°S or 63°S to the ice edge. To determine phytoplankton groups, CHEMTAX analysis was undertaken on pigments measured using HPLC. Diatoms were the dominant component of phytoplankton communities, explaining 56% of variation in chlorophyll a (Chl a), with haptophytes also being a major component. Prior to sampling the sea ice had retreated in a south-westerly direction, leading to shorter ice-free periods in the west (< 44 days, ≤65°E) compared to east (> 44 days, ≥70°E), inducing a strong seasonal effect. The east was nutrient limited, indicated by low-iron forms of haptophytes, and higher silicate:nitrate drawdown ratios (5.1 east vs 4.3 west), pheophytin a (phaeo) concentrations (30.0 vs 18.4 mg m-2) and phaeo:Chl a ratios (1.06 vs 0.53). Biological influences were evident at northern stations between 75-80°E, where krill “super-swarms” and feeding whales were observed. Here, diatoms were depleted from surface waters likely due to krill grazing, as indicated by high phaeo:Chl a ratios (> 0.75), and continued presence of haptophytes, associated with inefficient filtering or selective grazing by krill. Oceanographic influences included deeper mixed layers reducing diatom biomass, and a bloom to the north of the southern Antarctic Circumpolar Current Front in the western survey area thought to be sinking as waters flowed from west to east. Haptophytes were influenced by the Antarctic Slope Front with high-iron forms prevalent to the south only, showing limited iron transfer from coastal waters. Cryptophytes were associated with meltwater, and greens (chlorophytes + prasinophytes) were prevalent below the mixed layer. The interplay of seasonal, biological and oceanographic influences on phytoplankton populations during TEMPO had parallels with processes observed in the BROKE and BROKE-West voyages conducted 25 and 15 years earlier, respectively. Our research consolidates understanding of the krill ecosystem to ensure sustainable management in East Antarctic waters.

Regional taxonomic variation of phytoplankton communities in the Southern Ocean remains largely uncharacterised despite the distinct trophic and biogeochemical roles of different taxa in anthropogenic carbon uptake, biogeochemical processes, and as the primary source of energy for marine ecosystems. Here we analysed 26 years of pigment data (14,824 samples between 32°S and the Antarctic coast) from over 50 voyages (1996 – 2022), using the phytoclass software. The analysis confirms that the Antarctic Polar Front (APF) is a circumpolar phytoplankton class boundary, separating haptophyte dominated communities to the north from diatom domination of chlorophyll a in the south, and thereby a biological analogue corresponding to the Biogeochemical Divide. Furthermore, community composition was remarkably similar in different zones south of the APF despite substantial spatial variation in biomass. This circumpolar characterisation of the geospatial distribution of phytoplankton community composition will contribute to improved modelling and projection of future change in ecosystems and carbon in the Southern Ocean.

The high biomass of diatom-dominated phytoplankton communities is critical for sustaining the iconic Antarctic marine food web. Among Southern Ocean phytoplankton, the abundance of diatoms is particularly important as this group is selectively grazed by krill — which are the crucial prey of whales, penguins, and fish. Diatoms also play a key role in biogeochemical cycling and carbon export. Here we show drastic changes in the taxonomic composition of Antarctic phytoplankton over the past 26 years, driven by factors such as declining sea ice concentration, reduced iron availability, and warming. Using a machine learning approach trained on 14,824 historic pigment samples, we show that the proportion of Antarctic diatoms has substantially declined by 18% (-7% per decade), whilst the proportion of other smaller, less-grazed phytoplankton groups, such as haptophytes and cryptophytes, increased by 6–10%. We find that 65–74% of the Antarctic continental shelf had statistically significant trends in the proportion of one or more phytoplankton taxonomic groups (p < 0.05). These recent shifts in phytoplankton assemblages will have reduced food availability for grazers and thus Antarctica’s top predators, whilst also diminishing the biological pump and export, likely increasing atmospheric carbon dioxide (CO2) levels.

A compiled set of in situ data is important to evaluate the quality of ocean-colour satellite-data records. Here we describe the data compiled for the validation of the ocean-colour products from the ESA Ocean Colour Climate Change Initiative (OC-CCI). The data were acquired from several sources (MOBY, BOUSSOLE, AERONET-OC, SeaBASS, NOMAD, MERMAID, AMT, ICES, HOT, GeP&CO), span between 1997 and 2012, and have a global distribution. Observations of the following variables were compiled: spectral remote-sensing reflectances, concentrations of chlorophyll a, spectral inherent optical properties and spectral diffuse attenuation coefficients. The data were from multi-project archives acquired via the open internet services or from individual projects, acquired directly from data providers. Methodologies were implemented for homogenisation, quality control and merging of all data. No changes were made to the original data, other than averaging of observations that were close in time and space, elimination of some points after quality control and conversion to a standard format. The final result is a merged table designed for validation of satellite-derived ocean-colour products and available in text format. Metadata of each in situ measurement (original source, cruise or experiment, principal investigator) were preserved throughout the work and made available in the final table. Using all the data in a validation exercise increases the number of matchups and enhances the representativeness of different marine regimes. By making available the metadata, it is also possible to analyse each set of data separately. The compiled data are available at doi: 10.1594/PANGAEA.854832 (Valente et al., 2015).

Surface dissolved dimethylsulfide (DMS) and depth-integrated dimethylsulfoniopropionate (DMSP) measurements were made from March to April 2004 during the SOLAS Air–Sea Gas Exchange Experiment (SAGE), a multiple iron enrichment experiment in subantarctic waters SE of New Zealand. During the first two iron enrichments, chl a and DMS production were constrained, but during the third enrichment, large pulses of DMS occurred in the fertilised IN patch, compared with the unfertilised OUT patch. During the third and fourth iron infusions, total chl a concentrations doubled from 0.52 to 1.02 µg/L. Hapto8s and prasinophytes accounted for 50%, and 20%, respectively, of total chl a. The large pulses of DMS during the third iron enrichment occurred during high dissolved DMSP concentrations and wind strength; changes in dinoflagellate, haptophyte, and cyanobacteria biomass; and increased microzooplankton grazing that exerted a top down control on phytoplankton production. A further fourth iron enrichment did cause surface waters to increase in DMS, but the effect was not as great as that recorded in the third enrichment. Differences in the biological response between SAGE and several other iron enrichment experiments were concluded to reflect microzooplankton grazing activities and the microbial loop dominance, resulting from mixing of the MLD during storm activity and high winds during iron enrichment.

Ozone depletion and climate change are causing the Southern Annular Mode (SAM) to become increasingly positive, driving stronger winds southward in the Southern Ocean (SO), with likely effects on phytoplankton habitat due to possible changes in ocean mixing, nutrient upwelling, and sea ice characteristics. This study examined the effect of the SAM and 12 other environmental variables on the abundance of siliceous and calcareous phytoplankton in the seasonal ice zone (SIZ) of the SO. A total of 52 surface-water samples were collected during repeat resupply voyages between Hobart, Australia, and Dumont d'Urville, Antarctica, centred around longitude 142∘ E, over 11 consecutive austral spring–summer seasons (2002–2012), and spanning 131 d in the spring–summer from 20 October to 28 February. A total of 22 taxa groups, comprised of individual species, groups of species, genera, or higher taxonomic groups, were analysed using CAP analysis (constrained analysis of principal coordinates), cluster analysis, and correlation. Overall, satellite-derived estimates of total chlorophyll and measured depletion of macronutrients both indicated a more positive SAM was associated with greater productivity in the SIZ. The greatest effect of the SAM on phytoplankton communities was the average value of the SAM across 57 d in the previous austral autumn centred around 11 March, which explained 13.3 % of the variance in community composition in the following spring–summer. This autumn SAM index was significantly correlated pair-wise (p<0.05) with the relative abundance of 12 of the 22 taxa groups resolved. A more positive SAM favoured increases in the relative abundance of large Chaetoceros spp. that predominated later in the spring–summer and reductions in small diatom taxa and siliceous and calcareous flagellates that predominated earlier in the spring–summer. Individual species belonging to the abundant Fragilariopsis genera responded differently to the SAM, indicating the importance of species-level observation in detecting SAM-induced changes in phytoplankton communities. The day through the spring–summer on which a sample was collected explained a significant and larger proportion (15.4 %) of the variance in the phytoplankton community composition than the SAM, yet this covariate was a proxy for such environmental factors as ice cover and sea surface temperature, factors that are regarded as drivers of the extreme seasonal variability in phytoplankton communities in Antarctic waters. The impacts of SAM on phytoplankton, which are the pasture of the SO and principal energy source for Antarctic life, would have ramifications for both carbon export and food availability for higher trophic levels in the SIZ of the SO.

Chlorophyll a is the most commonly used indicator of phytoplankton biomass in the marine environment. It is relatively simple and cost effective to measure when compared to phytoplankton abundance and is thus routinely included in many surveys. Here we collate 173, 333 records of chlorophyll a collected since 1965 from Australian waters gathered from researchers on regular coastal monitoring surveys and ocean voyages into a single repository. This dataset includes the chlorophyll a values as measured from samples analysed using spectrophotometry, fluorometry and high performance liquid chromatography (HPLC). The Australian Chlorophyll a database is freely available through the Australian Ocean Data Network portal ( https://portal.aodn.org.au/ ). These data can be used in isolation as an index of phytoplankton biomass or in combination with other data to provide insight into water quality, ecosystem state, and relationships with other trophic levels such as zooplankton or fish.

Polar waters may be highly impacted by ocean acidification (OA) due to increased solubility of CO2 at colder water temperatures. Three experiments examining the influence of OA on primary and bacterial production were conducted during austral summer at Davis Station, East Antarctica (68°35′ S, 77°58′ E). For each experiment, six minicosm tanks (650 L) were filled with 200 μm filtered coastal seawater containing natural communities of Antarctic marine microbes. Assemblages were incubated for 10 to 12 days at CO2 concentrations ranging from pre-industrial to post-2300. Primary and bacterial production rates were determined using NaH14CO3 and 14C-leucine, respectively. Net community production (NCP) was also determined using dissolved oxygen. In all experiments, maximum photosynthetic rates (Pmax, mg C mg chl a− 1 h− 1) decreased with elevated CO2, clearly reducing rates of total gross primary production (mg C L− 1 h− 1). Rates of cell-specific bacterial productivity (μg C cell− 1 h− 1) also decreased under elevated CO2, yet total bacterial production (μg C L− 1 h− 1) and cell abundances increased with CO2 over Days 0–4. Initial increases in bacterial production and abundance were associated with fewer heterotrophic nanoflagellates and therefore less grazing pressure. The main changes in primary and bacterial productivity generally occurred at CO2 concentrations > 2 × present day (> 780 ppm), with the same responses occurring regardless of seasonally changing environmental conditions and microbial assemblages. However, NCP varied both within and among experiments, largely due to changing nitrate + nitrite (NOx) availability. At NOx concentrations < 1.5 μM photosynthesis to respiration ratios showed that populations switched from net autotrophy to heterotrophy and CO2 responses were suppressed. Overall, OA may reduce production in Antarctic coastal waters, thereby reducing food availability to higher trophic levels and reducing draw-down of atmospheric CO2, thus forming a positive feedback to climate change. NOX limitation may suppress this OA response but cause a similar decline.

The impacts of anthropogenic enhancement of the partial pressure of carbon dioxide (pCO(2)) on marine organisms remain unclear, especially in Antarctic waters, which are predicted to be amongst the earliest and most severely affected by the consequent changes in ocean chemistry. Marine microbes are the base of the Antarctic food chain, and the nature of their response to elevated pCO(2) is important as they are key determinants of the biogeochemical cycles that affect global climate. We studied the response of a natural community of Antarctic marine microbes from near-shore waters off Davis Station, Antarctica, to pCO(2) ranging from the concentration in the water column at the time the experiment began (ambient, 84 mu atm) to that predicted by the year 2300 (2423 mu atm) using 6 gas-tight, environmentally controlled tanks (minicosms; 650 l) to which CO2-saturated seawater was added. The microbial community showed little difference between 84 and 643 mu atm CO2 (0.2 to 1.7 times present), indicating that they can tolerate the large seasonal range in pCO(2) in Antarctic coastal waters. Concentrations >= 1281 mu atm reduced the accumulation rate of chlorophyll and particulate carbon, changed the microbial community, and enhanced the relative abundance of small phytoplankton. If our results are indicative of the future responses of Antarctic marine microbes, elevated CO2 could profoundly affect the structure and function of the Antarctic food web by reducing the availability of food for higher trophic levels and decreasing the efficiency of the biological pump.

Strengths of numerical relationships between phytoplankton abundance estimates made by microscopy and CHEMTAX have often been tested using regression analysis. To specifically test agreement, where data points lie along a line of equality, the Bland and Altman technique is commonly used in the medical literature and applied here to phytoplankton analysis for the first time (simultaneously with regression). Our analyses are based on a sample set collected off Coffs Harbour (∼ 30°S), Eastern Australia. While comparing abundance estimates of different phytoplankton pigment‐types derived from microscopy and CHEMTAX we specifically aim at: (1) determining the usefulness of the Bland and Altman technique in comparing phytoplankton abundance estimates made by both quantification techniques, and (2) identifying the lowest taxonomic level (i.e., interclass or intraclass level) at which phytoplankton abundance estimates agree. Our results suggest that Bland and Altman analysis is highly suited to compare phytoplankton abundance estimates made by microscopy and CHEMTAX. It delivered a quantifiable difference of chlorophyll a concentrations between abundance estimates, which may benefit the future calibration of phytoplankton quantification techniques. Both Bland and Altman and regression analyses were suited to resolve imbalances between phytoplankton abundance estimates made by microscopy and CHEMTAX. Best agreement was found within dinoflagellates (class‐level), poor agreement within three diatom pigment‐types (intraclass level). We attributed the poor agreement within diatom abundance estimates to classification errors of microscopically determined taxa into pigment‐types. Intraspecific pigment composition seems more variable than generally assumed, calling for studies resolving this variation to further conform abundance estimates made by microscopy and CHEMTAX.

Abstract. Our current knowledge of broad-scale patterns of primary production in the Southern Ocean is derived from satellite ocean-colour estimates of chlorophyll a (Chl a) in the open ocean, typically in spring-summer. Here, we provide evidence that large-scale intra-ice phytoplankton surface aggregation occur off the coast of Antarctica during austral autumn, and that these "blooms" are largely undetected in satellite ocean-colour time series (which mask the ice-covered ocean). We present an analysis of (i) true-colour (visible) satellite imagery in combination with (ii) conventional ocean-colour data, and (iii) direct sampling from a research vessel, to identify and characterise a large-scale intra-ice algal occurrence off the coast of East Antarctica in early autumn (March) 2012. We also present evidence of these autumn "blooms" in other regions (for example, Princess Astrid Coast in 2012) and other years (for example, Terra Nova Bay in 2015) implying regular and widespread occurrence of these phenomena. The occurrence of such undetected algal accumulations implies that the magnitude of primary production in the Southern Ocean is currently underestimated.

The coastline of Australia spans tropical to temperate latitudes and encompasses a highly diverse phytoplankton community. Yet little is known about environmental driving forces of compositional and distributional patterns in natural phytoplankton communities of Australia. We investigate the relationships of phytoplankton (pico-, nano-, microphytoplankton, determined by microscopy and CHEMTAX) with a variety of environmental variables along cross-shelf gradients. Case studies were conducted in two highly distinct oceanographic regions of Australia (2010/2012): the tropical-temperate Coffs Harbour region (~30°S, 153°E), where the shelf is narrow (~30km), and the tropical Kimberley region (~16°S, 122°E), where the shelf is wide (~200km). We distinguished three water masses in both study regions: relatively cold, nutrient-rich inshore waters; oligotrophic, stratified offshore waters; and cold, nutrient-rich deep waters. Most phytoplankton taxa (cyanobacteria, cryptophytes, dinoflagellates, haptophytes and prasinophytes) showed group-specific relationships with similar environmental variables in both regions. Diatoms occurred in nutrient-rich inshore waters in the Kimberley, whereas they were widely spread across the narrow continental shelf at Coffs Harbour. Off Coffs Harbour, a senescent bloom of the diatom Leptocylindrus danicus probably caused shelf-scale surface nutrient depletion. While microphytoplankton clearly increased, pico- and nanophytoplankton decreased with distance from the coast over the wide shelf in the Kimberley region. In contrast, the abundance of individual phytoplankton size-classes remained relatively constant across the narrow Coffs Harbour shelf. We conclude that general similarities exist between the relationship of phytoplankton and cross-shelf environmental variables in the two sites and assign differences primarily to the varying spatial resolution of our case studies.

Introduction Conclusions References Tables Figures

Surface ocean productivity mediates the transfer of carbon to the deep ocean and in the process regulates atmospheric CO 2 levels. A common axiom in oceanography is that large phytoplankton contribute disproportionally to the transfer of carbon to the deep ocean because of their greater ability to escape grazing pressure, build biomass, and sink. In the present study, we assessed the relationship of net community production to phytoplankton assemblages and plankton size distribution in the Sub‐Antarctic Zone and northern reaches of the Polar Frontal Zone in the Australian sector of the Southern Ocean. We reanalyzed and synthesized previously published estimates of O 2 /Ar net community oxygen production (NCP) and triple‐O 2 isotopes gross primary oxygen production (GPP) along with microscopic and pigment analyses of the microbial community. Overall, we found that the axiom that large phytoplankton drive carbon export was not supported in this region. Mixed‐layer‐depth‐integrated NCP was correlated to particulate organic carbon (POC) concentration in the mixed layer. While lower NCP/GPP and NCP/POC values were generally associated with communities dominated by smaller plankton size (as would be expected), these communities did not preclude high values for both properties. Vigorous NCP in some regions occurred in the virtual absence of large phytoplankton (and specifically diatoms) and in communities dominated by nanoplankton and picoplankton. We also observed a positive correlation between NCP and the proportion of the phytoplankton community grazed by microheterotrophs, supporting the mediating role of grazers in carbon export. The novel combination of techniques allowed us to determine how NCP relates to upper ocean ecosystem characteristics and may lead to improved models of carbon export.

Around one third of all anthropogenic CO2 emissions have been absorbed by the oceans, causing changes in seawater pH and carbonate chemistry. These changes have the potential to affect phytoplankton, which are critically important for marine food webs and the global carbon cycle. However, our current knowledge of how phytoplankton will respond to these changes is limited to a few laboratory and mesocosm experiments. Long-term experiments are needed to determine the vulnerability of phytoplankton to enhanced pCO(2`). Maintaining phytoplankton cultures in exponential growth for extended periods of time is logistically difficult and labour intensive. Here we describe a continuous culture system that greatly reduces the time required to maintain phytoplankton cultures, and minimises variation in experimental pCO(2) treatments over time. This system is simple, relatively cheap, flexible, and allows long-term experiments to be performed to further our understanding of chronic responses and adaptation by phytoplankton species to future ocean acidification.

Increased seawater pCO2 has the potential to alter phytoplankton biochemistry, which in turn may negatively affect the nutritional quality of phytoplankton as food for grazers. Our aim was to identify how Antarctic phytoplankton, Pyramimonas gelidicola, Phaeocystis antarctica, and Gymnodinium sp., respond to increased pCO2. Cultures were maintained in a continuous culture setup to ensure stable CO2 concentrations. Cells were subjected to a range of pCO2 from ambient to 993 µatm. We measured phytoplankton response in terms of cell size, cellular carbohydrate content, and elemental, pigment and fatty acid composition and content. We observed few changes in phytoplankton biochemistry with increasing CO2 concentration which were species-specific and predominantly included differences in the fatty acid composition. The C:N ratio was unaffected by CO2 concentration in the three species, while carbohydrate content decreased in Pyramimonas gelidicola, but increased in Phaeocystis antarctica. We found a significant reduction in the content of nutritionally important polyunsaturated fatty acids in Pyramimonas gelidicola cultures under high CO2 treatment, while cellular levels of the polyunsaturated fatty acid 20:5ω3, EPA, in Gymnodinium sp. increased. These changes in fatty acid profile could affect the nutritional quality of phytoplankton as food for grazers, however, further research is needed to identify the mechanisms for the observed species-specific changes and to improve our ability to extrapolate laboratory-based experiments on individual species to natural communities.