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Vegetation surveys were carried out in four different study areas in the Sakha Republic, Russia: in the mountainous region of the Verkhoyansk Range within the Oymyakonsky and Tomponsky District (Event EN21-201 - EN21-219), and in three lowland regions of Central Yakutia within the Churapchinsky, Tattinsky and the Megino-Kangalassky District (Event EN21220 - EN21264). The study area is located within the boreal forest biome that is underlain by permafrost soils. The aim was to record the projective ground vegetation in different boreal forest types studied during the RU-Land_2021_Yakutia summer field campaign in August and September 2021.Ground vegetation was surveyed for different vegetation types within a circular forest plot of 15m radius. Depending on the heterogeneity of the forest plot, multiple vegetation types (VA, VB, or VC) were chosen for the survey. The assignment of a vegetation type is always unique to a site. Their cover on the circular forest plot was recorded in percent.In total, 84 vegetation types at 58 forest plots were assessed. All data were collected by scientists form the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) Germany, the University of Potsdam Germany, and the North-Easter Federal University of Yakutsk (NEFU) Russia.

This data was collected as a part of a mesocosm study to investigate the ecosystem impacts of ocean alkalinity enhancement, within the EU H2020 OceanNETs project. Nine mesocosms were deployed in Taliarte Harbour (Gran Canaria, Spain) and were regularly sampled using integrated water samplers between 10th September-25th October 2021. A gradient design was used in this experiment with a total of nine different alkalinity concentrations. Seawater alkalinity ranged between ambient (0 µeq kg-1 added alkalinity, OAE0) and 2400 µeq kg-1 additional alkalinity (OAE2400). The alkalinity levels increased in equal intervals of 300 µeq kg-1 across nine mesocosms (OAE0, OAE300, OAE600, OAE900, OAE1200, OAE1500, OAE1800, OAE2100, OAE2400). This data set contains metazoan zooplankton biomass (µgC per L) from these nine mesocosms. Biomass was calculated based on zooplankton abundances transformed using carbon mass conversion factors. Metazoan zooplankton were sampled with apstein net (ø17cm, mesh size 55µm, 64.06285L) hauls taken every two days (except for days 5 and 9). Zooplankton were size fractioned and assessed in the correspondent size class (small: 55-200µm; medium: 200-500µm; large: 500µm-3mm). Within each size class, all organisms were counted and identified to the lowest possible taxonomic level, and developmental stages were differentiated where possible. Zooplankton abundances (individuals per L) converted to carbon biomass (µgC per L) using biomass conversion factors. Conversion factors are obtained from different sources (Sanchez et al. (in prep)). Briefly: i) metazoan zooplankton functional groups were sampled and measured for carbon biomass using an elemental analyser at specific points throughout the experiment, ii) individual zooplankton were photographed, measured, and their biovolumes and carbon masses derived using standard conversions cited in the literature, iii) zooplankton conversion factors from KOSMOS Gran Canaria 2019 (https://doi.pangaea.de/10.1594/PANGAEA.971765). The experiment, which lasted 33 days, was divided into four response phases (see Sánchez et al. (in prep)): i) pretreatment (days 1 to 4, treatment was implemented on day 4), ii) immediate (days 5-10), iii) shorter term (days 11-22), iv) longer term (days 23 to 33). This data set is associated to the submission by Paul et al. (in review) (https://doi.pangaea.de/10.1594/PANGAEA.966941), so we refer to this data set for basic parameters like water temperature, salinity, pH and carbonate chemistry, to avoid repetition.

While the physical dimensions of climate change are now routinely assessed through multimodel intercomparisons, projected impacts on the global ocean ecosystem generally rely on individual models with a specific set of assumptions. To address these single-model limitations, we present standardized ensemble projections from six global marine ecosystem models forced with two Earth system models and four emission scenarios with and without fishing. We derive average biomass trends and associated uncertainties across the marine food web. Without fishing, mean global animal biomass decreased by 5% (±4% SD) under low emissions and 17% (±11% SD) under high emissions by 2100, with an average 5% decline for every 1 °C of warming. Projected biomass declines were primarily driven by increasing temperature and decreasing primary production, and were more pronounced at higher trophic levels, a process known as trophic amplification. Fishing did not substantially alter the effects of climate change. Considerable regional variation featured strong biomass increases at high latitudes and decreases at middle to low latitudes, with good model agreement on the direction of change but variable magnitude. Uncertainties due to variations in marine ecosystem and Earth system models were similar. Ensemble projections performed well compared with empirical data, emphasizing the benefits of multimodel inference to project future outcomes. Our results indicate that global ocean animal biomass consistently declines with climate change, and that these impacts are amplified at higher trophic levels. Next steps for model development include dynamic scenarios of fishing, cumulative human impacts, and the effects of management measures on future ocean biomass trends.

In Eastern Boundary Upwelling Systems nutrient-rich waters are transported to the ocean surface, fuelling high photoautotrophic primary production. Subsequent heterotrophic decomposition of the produced biomass increases the oxygen-depletion at intermediate water depths, which can result in the formation of oxygen minimum zones (OMZ). OMZs can sporadically accumulate hydrogen sulfide (H2S), which is toxic to most multicellular organisms and has been implicated in massive fish kills. During a cruise to the OMZ off Peru in January 2009 we found a sulfidic plume in continental shelf waters, covering an area >5500 km(2), which contained ∼2.2×10(4) tons of H2S. This was the first time that H2S was measured in the Peruvian OMZ and with ∼440 km(3) the largest plume ever reported for oceanic waters. We assessed the phylogenetic and functional diversity of the inhabiting microbial community by high-throughput sequencing of DNA and RNA, while its metabolic activity was determined with rate measurements of carbon fixation and nitrogen transformation processes. The waters were dominated by several distinct γ-, δ- and ε-proteobacterial taxa associated with either sulfur oxidation or sulfate reduction. Our results suggest that these chemolithoautotrophic bacteria utilized several oxidants (oxygen, nitrate, nitrite, nitric oxide and nitrous oxide) to detoxify the sulfidic waters well below the oxic surface. The chemolithoautotrophic activity at our sampling site led to high rates of dark carbon fixation. Assuming that these chemolithoautotrophic rates were maintained throughout the sulfidic waters, they could be representing as much as ∼30% of the photoautotrophic carbon fixation. Postulated changes such as eutrophication and global warming, which lead to an expansion and intensification of OMZs, might also increase the frequency of sulfidic waters. We suggest that the chemolithoautotrophically fixed carbon may be involved in a negative feedback loop that could fuel further sulfate reduction and potentially stabilize the sulfidic OMZ waters.

Thermal resistance of the coral-zooxanthellae symbiosis has been associated with chronic photoinhibition, increased antioxidant activity and protein repair involving high demands of nitrogen and energy. While the relative importance of heterotrophy as a source of nutrients and energy for cnidarian hosts, and as a means of nitrogen acquisition for their zooxanthellae, is well documented, the effect of feeding on the thermal sensitivity of the symbiotic association has been so far overlooked. Here we examine the effect of zooplankton feeding versus starvation on the bleaching susceptibility and photosynthetic activity of photosystem II (PSII) of zooxanthellae in the scleractinian coral Stylophora pistillata in response to thermal stress (daily temperature rises of 2-3 degrees C) over 10 days, employing pulse-amplitude-modulated chlorophyll fluorometry. Fed and starved corals displayed a decrease in daily maximum potential quantum yield (F (v)/F (m)) of PSII, effective quantum yield (F/F (m)') and relative electron transport rates over the course of 10 days. However after 10 days of exposure to elevated temperature, F (v)/F (m) of fed corals was still 50-70% higher than F (v)/F (m) of starved corals. Starved corals showed strong signs of chronic photoinhibition, which was reflected in a significant decline in nocturnal recovery rates of PSII relative to fed corals. This was paralleled by the progressive inability to dissipate excess excitation energy via non-photochemical quenching (NPQ). After 10 days, NPQ of starved corals had decreased by about 80% relative to fed corals. Feeding treatment had no significant effect on chlorophyll a and c (2) concentrations and zooxanthellae densities, but the mitotic indices were significantly lower in starved than in fed corals. Collectively the results indicate that exogenous food may reduce the photophysiological damage of zooxanthellae that typically leads to bleaching and could therefore play an important role in mediating the thermal resistance of some corals.

Changes in biomass and elemental composition (dry mass, W; carbon, C; nitrogen, N; hy- drogen, H) were studied in the laboratory during complete larval and early juvenile development of the southern stone crab Paralomis granulosa (Jacquinot). At 6 ± 0.5°C; total larval development from hatching to metamorphosis lasted ca. 56 d, comprising 2 demersal zoeal stages and a benthic mega- lopa, with mean stage durations of 5, 11 and 45 d, respectively. All larval stages of P. granulosa are lecithotrophic, and first feeding and growth were consistently observed immediately after meta- morphosis to the first juvenile crab stage. Regardless of presence or absence of food, W, C, N, and H decreased throughout larval development. Also the C:N mass ratio decreased significantly, from 7.2 at hatching to 4.2 at metamorphosis, indicating that a large initial lipid store remaining from the egg yolk was gradually utilised as an internal energy source. In total, about 68% of the initial quantities of C and H present at hatching, and 44% of N were lost during non-feeding larval development to meta- morphosis. Approximately 10% of the initially present C, N and H were lost with larval exuviae, half of which was lost in the megalopa stage alone. Hence, metabolic biomass degradation accounted for losses of ca. 59% in C and H, but for only 33% in N. Most of the losses in C and H reflected metabolic energy consumption (primarily lipid degradation), while ca. 1 /4 of the losses in N and 2 /3 of those in W were due to larval exuviation. Complete larval lecithotrophy is based on an enhanced maternal energy investment per offspring, and on energy-saving mechanisms such as low larval locomotory activity and low exuvial losses. These traits are interpreted as bioenergetic adaptations to food-limited condi- tions in subantarctic regions, where a pronounced seasonality limits the period of primary production.

Abstract The coastal waters off Peru are among the world’s most productive, thanks to the Humboldt Current and its strong coastal upwelling. Fisheries and an ever-expanding mariculture sector provide millions of Peruvians livelihoods, income, and nutrition. Coastal communities engaging with these sectors face a volatile environment they have historically adapted to. But when the COVID-19 pandemic unfolded in 2020, affecting all aspects of life, challenges for the fisheries and mariculture sectors emerged to a yet unprecedented extent. This work applies a mixed-method approach for documenting and analysing the effects of the pandemic on the Peruvian seafood sector and seafood worker’s economy in particular. Mobility restrictions and market closures disrupted seafood supply chains, altering access to nutrition and income for many people involved. Interviewees aimed to diversify livelihood strategies and use personal networks to withstand the crisis, while some established adaptation strategies, such as migration towards other fishing grounds, were largely impeded. Our results highlight the vulnerability of seafood value chains—mainly artisanal and small-scale fisheries—in the face of such a global crisis. The implications of the pandemic for the long-term sustainability of Peruvian coastal–marine activities are discussed and set into the context of previously experienced crises in the region.