Biological Productivity In Surface Waters Research Articles

Co-occurrence of a marine heatwave and a reported tomato jellyfish (<i>Crambione mastigophora</i> Maas, 1903) bloom in March 2020 at El Nido, Palawan, Philippines

Globally, observations on marine species during marine heatwaves (MHWs) help outline the scope of the MHW’s possible biological effects. In line with this effort, this paper presents a 2020 MHW that coincided with a reported ‘tomato jellyfish’ (Crambione mastigophora Maas, 1903) bloom on 23 March 2020 in the Corong-Corong Bay of Palawan, Philippines. Detecting a moderate MHW from 21 March to 04 April 2020, the analysis of sea surface temperatures revealed that most areas surrounding the bloom site attained their peak positive anomalies on the same day as the reported bloom. Certain physical mechanisms present in the first quarter of 2020 may have played a role in the occurrence of both events: the presence of cyclonic eddies and parallel monsoonal winds alongshore can induce upwelling which promotes biological productivity in surface waters, while the observed weakening of winds have been associated with anomalous warming of the sea surface. Further studies are still highly recommended to determine the exact causes of the jellyfish bloom and what conditions make it more likely to happen during MHWs. However, if the C. mastigophora is hypothetically able to continually bloom amidst warming temperatures, the increasing trend of MHW frequency and intensity in the West Philippine Sea (where the reported bloom site is situated) may consequently yield more future co-occurrences. This paper aims to hopefully contribute to the existing knowledge of possible biological impacts associated with extreme marine events, especially in the Philippine context where both jellyfish blooms and MHWs are understudied.

Ocean circulation and frontal structure near the southern Kerguelen Plateau: The physical context for the Kerguelen Axis ecosystem study

Oceanographic observations from ships, floats and remote sensing are used to describe the ocean circulation and frontal structure from the southern Kerguelen Plateau to the Antarctic margin. The flow of the Antarctic Circumpolar Current (ACC) is largely zonal upstream of the Kerguelen Plateau. The southern branch of the Polar Front and the northern branch of the southern ACC front (SACCF) are deflected to the north by the topography and cross the plateau through the Fawn Trough. The southern branch of the SACCF and the southern boundary of the ACC pass to the south of Banzare Bank, through the Princess Elizabeth Trough. These fronts turn sharply to the north on the eastern flank of the plateau, then retroflect to the south before continuing eastward. Satellite altimetry and float trajectories suggest the ACC regime to the east of the plateau is eddy-rich and characterised by extensive meandering of the ACC fronts, in contrast to the low eddy energy and zonal flow observed west of the plateau. The Antarctic Slope Current flows west along the upper continental slope, with hydrographic data indicating some of the flow turns offshore and feeds the Southern Boundary flow in the Western Boundary Current. Flow over the plateau itself is relatively quiescent and floats in this region have a long residence time (> 1 year). The regional circulation is closely associated with the distribution of biological productivity in surface waters, as revealed in satellite measurements of ocean colour, including high productivity in subpolar waters, along the eastern edge of the plateau and over the Antarctic continental shelf, moderate productivity over the plateau, and low productivity in ACC waters in the Fawn Trough and north of the SACCF.

Evidence for enhanced convection of North Pacific Intermediate Water to the low‐latitude Pacific under glacial conditions

AbstractWe provide high‐resolution foraminiferal stable carbon isotope (δ13C) records from the subarctic Pacific and Eastern Equatorial Pacific (EEP) to investigate circulation dynamics between the extratropical and tropical North Pacific during the past 60 kyr. We measured the δ13C composition of the epibenthic foraminiferal species Cibicides lobatulus from a shallow sediment core recovered from the western Bering Sea (SO201‐2‐101KL; 58°52.52′N, 170°41.45′E; 630 m water depth) to reconstruct past ventilation changes close to the source region of Glacial North Pacific Intermediate Water (GNPIW). Information regarding glacial changes in the δ13C of subthermocline water masses in the EEP is derived from the deep‐dwelling planktonic foraminifera Globorotaloides hexagonus at ODP Site 1240 (00°01.31′N, 82°27.76′W; 2921 m water depth). Apparent similarities in the long‐term evolution of δ13C between GNPIW, intermediate waters in the eastern tropical North Pacific and subthermocline water masses in the EEP suggest the expansion of relatively 13C‐depleted, nutrient‐enriched, and northern sourced intermediate waters to the equatorial Pacific under glacial conditions. Further, it appears that additional influence of GNPIW to the tropical Pacific is consistent with changes in nutrient distribution and biological productivity in surface waters of the glacial EEP. Our findings highlight potential links between North Pacific mid‐depth circulation changes, nutrient cycling, and biological productivity in the equatorial Pacific under glacial boundary conditions.

Influence of Asian monsoon and ENSO events on particle fluxes in the western subtropical Pacific

A time-series sediment trap was deployed from October 2007 to May 2011 in the western subtropical Pacific with the aim of understanding the seasonal and inter-annual variability on particle flux in response to El Niño-Southern Oscillation (ENSO) events. Total mass fluxes varied from 3.04mgm−2day−1 to 31.1mgm−2day−1, with high fluxes during February–April and low fluxes during other months. This seasonal variation was also characterized by a distinct change in the CaCO3 flux between the two periods. The marked increase in particle flux during February–April may be attributed to enhanced biological productivity in surface waters caused by strong wind-driven mixing in response to the western North Pacific monsoon system. The 2009/10 strong El Niño was accompanied by a significant reduction in particle flux, whereas the La Niña had no recognizable effect on particle flux in the subtropical Pacific. In particular, in the mature phase of the 2009/10 strong El Niño, the fluxes of organic carbon and biogenic silica decreased by 70–80% compared with those during the normal period, implying that the El Niño acted to suppress biological productivity in surface waters. The suppression of biological productivity during the 2009/10 strong El Niño is attributed to the decrease in precipitation due to the shift in the western Pacific warm pool. This finding is opposite that of other studies of the western equatorial Pacific, where El Niño events were observed to result in an increase in biological productivity and particle flux. The difference in particle flux between the western equatorial and subtropical Pacific is attributed to the regional differences in oceanic and atmospheric circulation systems generated by the strong El Niño.

Primary production and nitrogen regeneration processes in surface waters of the Peruvian upwelling system

Tracer experiments ( 15N and 13C) were carried out off the Peruvian upwelling system in order to evaluate the potential role of regenerated nitrogen in sustaining biological productivity in surface waters (0–15 m depth range). Rates of daily carbon uptake in surface waters showed values ranging between 6 and 200 mg C m −3 d −1. Maximum integrated rates were obtained in northern Peru (up to 5.5 g m −2 d −1). Parallel measurements of nitrogen uptake showed a stronger utilization of ammonium compared to nitrate at all stations, with surface ammonium uptake values reaching up to 0.15 μmol N L −1 d −1. Ammonium was also actively regenerated in surface waters, at rates as high as 0.5 μmol N L −1 d −1, whereas ammonium oxidation to nitrate (nitrification) occurred at lower rates (<0.15 μmol N L −1 d −1). Results obtained in this study showed active regeneration of N within the euphotic layer. Regenerated nitrate and ammonium are, therefore, available for primary producers within the euphotic zone and sustain a fraction of the observed photoautotrophic carbon fixation. The contribution of nitrogen regenerating processes to primary production in terms of DIN could represent as much as 50% of NH 4 assimilated in surface waters (through ammonium regeneration) as well as a variable fraction (2–16%) of nitrate through nitrification.

Long time series of deep water particle flux in three biogeochemical provinces of the northeast Atlantic

Long-term observations of the deep ocean particle flux from three sites in the northeast Atlantic (33°N, 22°W; 47°N, 20°W; 54°N, 20°W) provide the basis for comparison and characterization of the biogeochemical provinces in terms of sedimentation pattern. Deep ocean particle flux data (2000 m) for fluxes of total mass and the flux composition are presented and compared to published sediment trap data from this area to consider regional-scale variations in the quantity and composition of settling material. The observations show that in the northeast Atlantic gradient of decreasing mass flux from North to South, exists consistent with known changes of biological productivity in surface waters. This gradient is associated with similar trends in opal and particulate organic carbon, whereas calcium carbonate shows trend in the opposite direction. The changes in the composition of the settling material found along the transect are indicating that the calcium carbonate flux is critical in removing organic matter from the upper ocean to the deeper sink. Its role declines from the subtropical ocean (60–80% of the particle flux) towards North (< 40%) reflecting the decreasing importance of coccolithophorid/foraminiferal blooms for particle flux from the subtropical to the subpolar North Atlantic. In contrast, the role of biogenic silica (opal) in regard to the ballasting effect increases towards North. The northern sites have much higher percentage of biogenic silica than the sites in the South, because of the deep winter mixing and the seasonality of phytoplankton dominated by diatom blooms during spring and summer. The comparison of the seasonal pattern of particle flux with the seasonal pattern of surface chlorophyll a concentrations from SeaWiFS together with the similarity of the pattern observed in calcium carbonate and opal leads to the conclusion that the particle flux at two positions (33°N, 22°W; 47°N, 20°W) is fast and directly coupled to the phytoplankton dynamics in the overlying euphotic zone.

Southern Ocean iron enrichment experiment: carbon cycling in high- and low-Si waters.

The availability of iron is known to exert a controlling influence on biological productivity in surface waters over large areas of the ocean and may have been an important factor in the variation of the concentration of atmospheric carbon dioxide over glacial cycles. The effect of iron in the Southern Ocean is particularly important because of its large area and abundant nitrate, yet iron-enhanced growth of phytoplankton may be differentially expressed between waters with high silicic acid in the south and low silicic acid in the north, where diatom growth may be limited by both silicic acid and iron. Two mesoscale experiments, designed to investigate the effects of iron enrichment in regions with high and low concentrations of silicic acid, were performed in the Southern Ocean. These experiments demonstrate iron's pivotal role in controlling carbon uptake and regulating atmospheric partial pressure of carbon dioxide.

北太平洋の深海底コアから推測される最終氷期の世界

Comparing mutually the records of several deep-sea cores from the North Pacific, it is concluded that glacial ages had high accumulation rate of organic carbon and weak carbonate dissolution rate than interglacial ages. However, the increase of biological productivity in surface water generally causes the drop of the pH of the underlying water and leads to high carbonate dissolution. A key to solve this contradiction is probably carbonate particles in aeolian dust which were extensively supplied to the entire ocean during glacial ages. By dissolving the carbonate particles in water column, the alkalinity of the sea water increased. Hence the atmospheric CO2 was absorbed by the upwelling water with high alkalinity, as well as by the photosynthesis of marine plankton increased during glacial ages. The variation of atmospheric CO2 concentration is not related to the deep water circulation but to the conditions of the surface and middle layers in the ocean.

Changes of lead and barium with time in California off-shore basin sediments

During ancient times the natural deposition fluxes of lead which can be leached with dilute acid from sediments in Santa Barbara, Santa Monica and San Pedro basins offshore from the Los Angeles Urban complex, were about 0.7, 0.1 and 0.2 μg Pb/cm 2 yr respectively. Since there was little difference in biological productivity in surface waters of these basins, it is proposed that clay is a major transport vehicle for sequestered soluble lead, which then explains why the lead deposition flux within the Santa Barbara basin was so much larger compared to the other basins. The fluxes of silicate mud in the basins in ancient times were about 92, 19 and 30 mg/cm 2 yr in Santa Barbara, Santa Monica and San Pedro basins respectively. Today deposition fluxes of acid soluble lead within these three basins are 3- to 9-fold greater, being about 2.1, 1.1 and 1.8 μg Pb/cm 2 yr respectively, partly in the form of directly deposited large sewage particles, which account for none, 2 3 and 3 4 of the total industrial lead deposition fluxes in the respective basins. Concentrations of leachable lead in varve dated sediment layers increase with time and isotopic compositions of these leads change in accordance with corresponding known changes of isotopic compositions of industrial lead in the Los Angeles atmosphere. Lead remaining in acid leached sediment residues originates from igneous and clay minerals, exhibiting no change in concentration or isotopic composition since pre-industrial times. Deposition fluxes of total barium in sediments among the three basins were proportional to mass deposition fluxes before 1950 in the same manner as for lead. Afterwards, there are barium concentration maxima with time in both Santa Monica and San Pedro Basin sediments which are attributable to industrial sewage rather than to episodic erosion from barium-rich sedimentary evaporite strata exposed locally along the shore. An increase of barium concentrations in present day Santa Barbara basin sediments may reflect dispersal of barium-rich drilling mud from local drilling operations.

Geochemical and mineralogical control of different genetic types of deep-sea nodules from the Pacific Ocean

Deep-sea nodules from the Northeast Pacific nodule belt and the Southeast Pacific (Sonne Basin), being formed in areas bordering the equatorial zone of high biological productivity, accumulate by two basically different growth processes: (A) early diagenetic growth by supply from pore water and (B) hydrogenetic growth by supply from near-bottom sea-water. These growth processes lead to different genetic types of nodules: early diagenetic type A, hydrogenetic type B, and mixed-type AB; a further type AC, very rich in Mn, is being formed by increasing influence of early diagenesis. These types can clearly be distinguished by their shapes, surface textures, mineral constituents of oxide fraction, internal microstructures, and geochemistry. A genetical classification is being proposed on the basis of statistically computed interelement relationships. Todorokite, very poor in Fe, is the main Mn phase in the early diagenetic substance; δ-MnO2 intimately intergrown with FeOOH · xH2O is the main phase in the hydrogenetic substance. Consequently an important difference can be pointed out: the metal supply for the growth of the early diagenetic nodules is based on an ionic solution of Me2+ (e. g. Mn2+, Ni2+, Cu2+, Zn2+), whereas the supply for the hydrogenetic nodules is caused by transport of colloidal particles. Mobilization of Mn2+ and fractionation from Fe is controlled by the amount of decomposing organic matter in the "peneliquid" layer of the sediments. The main factor controlling the intensity of early diagenesis is the biological productivity in surface waters. The crucial "point of reversal" at a Mn/Fe ratio of about 5, obtained by hyperbolical regression of the analyses of nodules from the Southeast Pacific, represents best concentrations in Ni and Cu. Mn/Fe quotients greater than 5 cause a decrease of Ni and Cu content. Nodules from the Northeast Pacific nodule belt generally contain higher concentrations in Cu than nodules from the Southeast Pacific. This can be explained by an additional supply of Cu transported below CCD by siliceous plankton.