Ocean acidification (OA) is expected to rise towards the end of the 21st century altering the life history traits in marine organisms. Upwelling systems will not escape OA, but unlike other areas of the ocean, cooling effects are expected to intensify in these systems. Regardless, studies evaluating the combined effects of OA and cooling remain scarce. We addressed this gap using a mesocosm system, where we exposed juveniles of the intertidal muricid snail Acanthina monodon to current and projected pCO₂ (500 vs. 1500 ppm) and temperature (15 vs. 10 °C) from the southeast Pacific upwelling system. After 9 weeks of experimental exposure to those conditions, we conducted three estimations of growth (wet weight, shell length and shell peristomal length), in addition to measuring calcification, metabolic and feeding rates and the ability of these organisms to return to the normal upright position after being overturned (self-righting). Growth, feeding and calcification rates increased in projected cooling conditions (10 °C) but were unaffected by pCO₂ or the interaction between pCO₂ and temperature. Instead, metabolic rates were driven by pCO₂, but a significant interaction with temperature suggests that in cooler conditions, metabolic rates will increase when associated with high pCO₂ levels. Snail self-righting times were not affected across treatments. These results suggest that colder temperatures projected for this area would drive this species growth, feeding and calcification, and consequently, some of its population biology and productivity. However, the snails may need to compensate for the increase in metabolic rates under the effects of ocean acidification. Although A. monodon ability to adjust to individual or combined stressors will likely account for some of the changes described here, our results point to a complex dynamic to take place in intertidal habitats associated with upwelling systems.

In recent years, dense Alexandrium ostenfeldii blooms have been reported in different coastal areas. In this study, we report for the first time the occurrence of A. ostenfeldii blooms associated with the detection of paralytic shellfish toxins (PSTs) in the Peruvian scallop (Argopecten purpuratus) from Paracas Bay. Alexandrium ostenfeldii blooms occurred at the end of summer and early fall, after the increase of riverine input and under stratified conditions following a decrease in wind velocity. The highest abundances occurred during warm sea surface temperatures (18–27 °C). High PST concentrations that exceed the maximum permissible level (800 μg STX eq. kg⁻¹) occurred even under low A. ostenfeldii abundances (20 × 10³ cells l⁻¹). Our results contribute to a better understanding of the dynamics of A. ostenfeldii in coastal systems influenced by riverine inputs and upwelling and can be used to improve monitoring programs and allow the implementation of mitigation measures along the Peruvian coast.

The Bohai Sea is well-known as a source of atmospheric methane (CH₄). However, the main regulate factors of the spatiotemporal distribution of CH₄ and its sea-to-air flux remain largely unknown. In this study, the observed CH₄ concentration ranged from 4.8 to 32.7 nmol/L and 3.1 to 15.2 nmol/L in August and November of 2014, respectively. The main factors that influence the distribution of CH₄ and its sea-to-air flux were stratification, solubility, and current structure for the mid-west depression basins, the permanent well-mixed seawater column and CH₄ source strength for the centre shallow ridge zone, and the upwelling for the east depression basin, respectively. Meanwhile, wind also plays an important role in sea-to-air CH₄ flux in the study area except the centre shallow ridge zone. Upwelling made the east depression basin the most intensive source of CH₄, with a flux of 2 to 4 times higher than the other sub-regions.

In the last decade, green Noctiluca scintillans with its symbiont and other dinoflagellates such as Cochlodinium polykrikoides, Prorocentrum micans and Scrippsiella trochoidea have become the dominant HABs, partially replacing the previously dominant diatoms and red Noctiluca scintillans, especially during the northeast monsoon. Fish kills in the Sea of Oman are linked to a slow seasonal decline in oxygen concentration from January to November, probably due to the decomposition of a series of algal blooms and the deep, low oxygen waters periodically impinging the Omani shelf. In the western Arabian Sea, cyclonic eddies upwell low oxygen, nutrient-rich water and the subsequent algal bloom decays and lowers the oxygen further and leads to fish kills. Warming of the surface waters by 1.2°C over the last 5 decades has increased stratification and resulted in a shoaling of the oxycline. This has increased the probability and frequency of upwelling low oxygen water and subsequent fish kills.

To investigate the upwelling influence on Hg biogeochemical cycles and the sedimentological changes during the previous ∼150years, four sediment box-cores were sampled along an inshore offshore transect on the Southeastern Brazilian continental shelf. Mercury values were found to be relatively low, with means ranging between 8.08 and 30.4ngg−1. Mercury fluxes along the sediment cores are directly related to the well documented historical regional activity and global atmospheric deposition. The narrow relationship between mercury and organic carbon suggest that upwelling phenomenon and primary production may play an important role on Hg input and distribution along continental shelf depositional settings.

Mercury (Hg) is a toxic globally spread pollutant that has been found at increasing concentrations in the South Atlantic Ocean. The present work provides the first insight into the total mercury (HgT, unfiltered waters) content in the water of the Brazilian Exclusive Economic Zone (BEEZ), within a 24°S to 20°S. Water samples were collected from surface to 3400 m depth along transects, and analyzed with atomic fluorescence. The mean HgT concentration for the Tropical Water mass (TW) was 6.3 ± 1.4 pM (n = 16), for the South Atlantic Central Water (SACW), 5.9 ± 0.7 pM (n = 8), for the Antarctic Intermediate Water (AAIW), 5.0 ± 0.6 pM (n = 2), for the Upper Circumpolar Deep Water (UCDW), 6.5 pM (n = 1), and for the North Atlantic Deep Water (NADW), 5.7 ± 0.9 pM (n = 12). HgT concentrations were highest throughout the BEEZ in comparison with other parts of the Atlantic Ocean, farther from the coast.

Assessing mercury (Hg) biomagnification requires the description of prey-predator relationships, for each species and ecosystem, usually based on carbon and nitrogen isotope analyses. Here, we analyzed two seabirds from the Humboldt Current ecosystem, the Guanay cormorant (Phalacrocorax bougainvillii) and the Peruvian booby (Sula variegata), as well as their main prey, the Peruvian anchovy (Engraulis ringens). We reported Hg concentrations, Hg biomagnification (BMF) and isotopic discrimination factors (Δ¹³C and Δ¹⁵N) in seabird whole blood. BMFs and Δ¹³C in our study (on wild birds where diet was not controlled) were similar to other piscivorous seabirds previously studied in captive settings, but Δ¹⁵N were lower than most captive experiments. We observed lower Hg concentrations in Humboldt seabirds compared to other oligotrophic ecosystems, possibly due to Hg biodilution in the high biomass of the first trophic levels. This work calls for a better characterization of Hg trophic dynamics in productive upwelling ecosystems.

Air-sea exchange of POPs and PAHs was assessed in Concepción Bay during January, summer 2015. Results showed low levels, in air and water, for POPs (1–20 pg m⁻³, and 6–50 pg L⁻¹, respectively) and for ΣPAHs (1–2 ng m⁻³ and 1–2 ng L⁻¹, respectively). The highest levels were found for PBDEs (200–20,000 pg L⁻¹) in the water samples (3-fold times higher than PCBs and OCP) and PBDE209 accounted for 90% of total ΣPBDEs. Air–sea exchange fluxes (ng m⁻² d⁻¹) were low in general, with exception of PBDEs showing values up to 40,000 ng m⁻² d⁻¹. Net deposition was found for PAHs, HCB and some PBDEs; while, BDE99, and BDE100 showed net volatilization. These findings contribute with new data of diffusive air-sea exchange on the southern hemisphere Pacific coast.

This study evaluates the rarely observed phenomenon of the simultaneous occurrences of phytoplankton blooms, hypoxia, and upwelling along the Zhejiang coast in the East China Sea. Results show that the upwelling uplifted bottom water to 5–10 m below the surface. In the upwelling region, phytoplankton blooms (Chl a = 10.9 μg L⁻¹) occurred and hypoxia or low-oxygen appeared below the surface water. High concentrations of nitrate and phosphate were regenerated in the hypoxic regions, corresponding with mean values (± SD) of 16.9 (± 1.5) and 0.90 (± 0.14) μM, respectively. The upwelling expanded the region of hypoxic water, which nearly reached the surface, thereby increasing the threat to marine life. In addition to fluvial nutrients, the upwelling of water with high nutrient levels, especially phosphates, can enhance phytoplankton blooms. The results suggest that hypoxia can become more severe due to further decomposition of bloom-derived organic matter after blooms crash.

The purpose of this work was to use the deep-water chimaera Hydrolagus colliei to examine the bioaccumulation and availability of Hg and Se in its deep-water habitat; the Se:Hg molar ratio was calculated to establish baseline information of the species and its associated ecosystem. The organisms were collected from northern Gulf of California. Hg levels in muscle were higher than liver and the opposite pattern happened with Se concentrations. Female had total lengths and weights higher than male but there were not found differences between elements concentrations by sex. Hg in muscle was correlated with weight. Molar Se:Hg ratio in muscle was the lowest compared to the liver. It was hypothesized that Hg and Se uptake to H. colliei were by its feeding habits because is a dominant species component of the demersal ecosystem and that play and important functional role in the control of oceanic ecosystem structure and function.