No Correlation Between Atmospheric Dust and Surface Ocean Chlorophyll‐a in the Oligotrophic Gulf of Aqaba, Northern Red Sea

Torfstein, Adi; Kienast, Markus

doi:10.1002/2017jg004063

Cited by 21 publications

(27 citation statements)

References 61 publications

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“…Our results confirm the presence of high loads of prokaryote and VLPs in dust suspended in the atmosphere over the Red Sea. Recent assessments of the chemical composition of dust in the northern Red Sea region report dust loads ranging from 20 to 30 μg m −3 (Torfstein et al, 2017; Torfstein and Kienast, 2018), which are 22-fold lower than those reported here. However, comparison of our results with other related studies is precluded by the absence of studies the quantifying the abundance of aerosol prokaryotes and VLPs particles in the Red Sea or even in the Mediterranean Sea, through which some of the air masses delivering microbes to the Red Sea transit.…”

Section: Discussioncontrasting

confidence: 75%

Airborne Prokaryote and Virus Abundance Over the Red Sea

et al. 2019

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Aeolian dust exerts a considerable influence on atmospheric and oceanic conditions negatively impacting human health, particularly in arid and semi-arid regions like Saudi Arabia. Aeolian dust is often characterized by its mineral and chemical composition; however, there is a microbiological component of natural aerosols that has received comparatively little attention. Moreover, the amount of materials suspended in the atmosphere is highly variable from day to day. Thus, understanding the variability of atmospheric dust loads and suspended microbes throughout the year is essential to clarify the possible effects of dust on the Red Sea ecosystem. Here, we present the first estimates of dust and microbial loads at a coastal site on the Red Sea over a 2-year period, supplemented with measurements from dust samples collected along the Red Sea basin in offshore waters. Weekly average dust loads from a coastal site on the Red Sea ranged from 4.6 to 646.11 μg m −3 , while the abundance of airborne prokaryotic cells and viral-like particles (VLPs) ranged from 77,967 to 1,203,792 cells m −3 and from 69,615 to 3,104,758 particles m −3 , respectively. To the best of our knowledge, these are the first estimates of airborne microbial abundance in this region. The elevated concentrations of resuspended dust particles and suspended microbes found in the air indicate that airborne microbes may potentially have a large impact on human health and on the Red Sea ecosystem.

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Section: Discussioncontrasting

confidence: 75%

Airborne Prokaryote and Virus Abundance Over the Red Sea

et al. 2019

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“…It is important to reiterate that the above-described structure of the 2016 event is largely consistent with the sequence of March–April 2015, indicating the observed patterns are systematic, rather than reflecting sampling biases or random signals within natural variability. In addition, previous comparisons of Chl- a surface concentrations between monthly resolved sampling in the deep GOA ( station A ) and daily resolved sampling at the IUI shore, display strong consistency 42 . Thus, the combined evidence suggests a systematic driving mechanism rather than chaotic seawater circulation patterns (e.g., eddies or patchiness 43 ) is the fundamental modulator of the observed daily timescale variability of PF fluxes.…”

Section: Discussionmentioning

confidence: 72%

“…Chl- a concentrations and sea surface temperatures (SST) were measured daily by the Israel National Monitoring Program (NMP) ( https://www.iui-eilat.ac.il/Research/NMPmeteodata.aspx ) at the pier of the Interuniversity Institute (IUI) for Marine Sciences at Eilat (Supplementary Fig. S1 ) and have been shown to be consistent with coeval values at station A 42 . Additionally, the NMP measured monthly profiles of water column temperatures, salinity, Chl- a concentrations, nutrient contents (TON, NO 2 − , NO 3 − , PO 4 3− , Si(OH) 4 )) at Station A (29° 28.22′ N, 34° 55.50′ E).…”

Section: Methodsmentioning

confidence: 99%

The daily resolved temperature dependence and structure of planktonic foraminifera blooms

Chernihovsky

Almogi‐Labin

Kienast

et al. 2020

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Planktonic foraminifera (PF) life cycles are highly sensitive to marine conditions, which are evolving rapidly due to anthropogenic climate change. Even though PF shells in the sedimentary record serve as prominent proxies of past ocean conditions, very little is still known about their life cycles, particularly in oligotrophic environments. Here, we present a full annual record of PF fluxes (> 63 µm) from the oligotrophic Gulf of Aqaba, northern Red Sea, sampled at daily timescales during 2015–2016 using an automated time-series sediment trap. These results are coupled with daily surface chlorophyll-a concentrations, sea surface temperatures (SSTs), particulate organic carbon and bulk fluxes, together with monthly resolved vertical profiles of chlorophyll-a, temperatures and nutrient concentrations. The annual cycle of PF fluxes is controlled by SST changes that drive water column mixing and changes in food availability. PF species flux patterns and succession dynamics vary throughout the year, displaying large variability on previously undocumented daily-weekly timescales, and are not synchronized with lunar periodicity. On daily timescales, spring blooms show a complex structure and interplay between SSTs, chlorophyll-a surface concentrations and PF fluxes. These events deliver about a third of the total annual PF flux over a period of several weeks.

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“…Another source of nitrogen which could significantly affect this region is atmospheric deposition, as the Gulf of Aqaba receives considerable dust input from the surrounding deserts. Recently, it has been shown that atmospheric dust input does not correlate with chlorophyll variability in surface waters of the Gulf of Aqaba (Torfstein and Kienast, 2018). In contrast, a previous study suggested that atmospheric deposition of nitrogen could support over 10 % of surface primary production in the region, based on measurements of local aerosol composition and a dust deposition model (Chen et al, 2007).…”

Section: Limitations and Uncertaintiesmentioning

confidence: 94%

Modelling the biogeochemical effects of heterotrophic and autotrophic N<sub>2</sub> fixation in the Gulf of Aqaba (Israel), Red Sea

2018

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Abstract. Recent studies demonstrate that marine N2 fixation can be carried out without light by heterotrophic N2 fixers (diazotrophs). However, direct measurements of N2 fixation in aphotic environments are relatively scarce. Heterotrophic as well as unicellular and colonial photoautotrophic diazotrophs are present in the oligotrophic Gulf of Aqaba (northern Red Sea). This study evaluates the relative importance of these different diazotrophs by combining biogeochemical models with time series measurements at a 700 m deep monitoring station in the Gulf of Aqaba. At this location, an excess of nitrate, relative to phosphate, is present throughout most of the water column and especially in deep waters during stratified conditions. A relative excess of phosphate occurs only at the water surface during nutrient-starved conditions in summer. We show that a model without N2 fixation can replicate the observed surface chlorophyll but fails to accurately simulate inorganic nutrient concentrations throughout the water column. Models with N2 fixation improve simulated deep nitrate by enriching sinking organic matter in nitrogen, suggesting that N2 fixation is necessary to explain the observations. The observed vertical structure of nutrient ratios and oxygen is reproduced best with a model that includes heterotrophic as well as colonial and unicellular autotrophic diazotrophs. These results suggest that heterotrophic N2 fixation contributes to the observed excess nitrogen in deep water at this location. If heterotrophic diazotrophs are generally present in oligotrophic ocean regions, their consideration would increase current estimates of global N2 fixation and may require explicit representation in large-scale models.

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No Correlation Between Atmospheric Dust and Surface Ocean Chlorophyll‐a in the Oligotrophic Gulf of Aqaba, Northern Red Sea

Cited by 21 publications

References 61 publications

Airborne Prokaryote and Virus Abundance Over the Red Sea

Airborne Prokaryote and Virus Abundance Over the Red Sea

The daily resolved temperature dependence and structure of planktonic foraminifera blooms

Modelling the biogeochemical effects of heterotrophic and autotrophic N<sub>2</sub> fixation in the Gulf of Aqaba (Israel), Red Sea

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No Correlation Between Atmospheric Dust and Surface Ocean Chlorophyll‐a in the Oligotrophic Gulf of Aqaba, Northern Red Sea

Cited by 21 publications

References 61 publications

Airborne Prokaryote and Virus Abundance Over the Red Sea

Airborne Prokaryote and Virus Abundance Over the Red Sea

The daily resolved temperature dependence and structure of planktonic foraminifera blooms

Modelling the biogeochemical effects of heterotrophic and autotrophic N&lt;sub&gt;2&lt;/sub&gt; fixation in the Gulf of Aqaba (Israel), Red Sea

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Modelling the biogeochemical effects of heterotrophic and autotrophic N<sub>2</sub> fixation in the Gulf of Aqaba (Israel), Red Sea