Regional validation of the use of diatoms in ice cores from the Antarctic Peninsula as a Southern Hemisphere Westerly Wind proxy

The Southern Hemisphere Westerly Winds are among the most important drivers of recently observed environmental changes in West Antarctica. However, the lack of long-term wind records in this region hinders our ability to assess the long-term context of these variations. Ice core proxy records yield valuable information about past environmental changes, although current proxies present limitations when aiming to reconstruct past winds. Here we present the first regional wind study based on the novel use of diatoms preserved in Antarctic ice cores. We assess the temporal variability in diatom abundance and its relation to regional environmental parameters spanning a 20-year period across three sites in the southern Antarctic Peninsula and Ellsworth Land, Antarctica. Correlation analyses reveal that the temporal variability of diatom abundance from high elevation ice core sites is driven by changes in wind strength over the core of the Southern Hemisphere Westerly Wind belt. Validating the use of diatoms preserved in ice cores from the Southern Antarctic Peninsula and Ellsworth Land as a proxy for reconstructing past variations in wind strength over the Pacific sector of the Southern Hemisphere Westerly Wind belt.

ANALYSIS OF NITRATE, PHOSPHATE, AND SILICATE CONTENT AND THEIR EFFECTS ON PLANKTONIC ABUNDANCE IN THE ESTUARY WATERS OF BATANG ARAU OR PADANG CITY WEST SUMATRA PROVINCE

The entry of nutrients (nitrate, phosphate and silicate) from land-based anthropogenic activities (industry, agriculture and household waste) through rivers can potentially cause changes in water quality and will affect fertility and aquatic organisms such as phytoplankton. These three nutrients play an important role in the living tissue cells of living organisms and in the photosynthesis process. This study aims to analyze the effect of nitrate, phosphate and silicate content on the plankton abundance in the estuary of the Batang Arau River, Padang, West Sumatra. The method used is a survey method, the determination of the sampling station is done by purposive sampling, data were analysed by Excel and SPSS Software. Based on the results of laboratory analysis, the nitrate content ranged from 0,117 to 0,485 mg/l, phosphate content from 0,239 to 0,704 mg/l, and silicate content from 0,031 to 0,685 mg/l. Planktonic diatom abundance in the estuary of the Batang Arau River ranges from 194 to 750 ind/l. The results of the statistical analysis of the effect of nitrate, phosphate and silicate with an abundance of diatoms are expressed by the equation Y = 743,019 - 481,828Nitrate - 199,552Phosphate - 172,971Silicate. This equation explains that the effect of nitrate, phosphate and silicate content on diatom abundance has an inverse or negative relationship, where nitrate, phosphate and silicate levels increase, the diatom abundance will decrease. The difference of content and the relationship between parameters analyzed in this research are discussed.

The Combined Effects of Increased pCO2 and Warming on a Coastal Phytoplankton Assemblage: From Species Composition to Sinking Rate

In addition to ocean acidification, a significant recent warming trend in Chinese coastal waters has received much attention. However, studies of the combined effects of warming and acidification on natural coastal phytoplankton assemblages here are scarce. We conducted a continuous incubation experiment with a natural spring phytoplankton assemblage collected from the Bohai Sea near Tianjin. Experimental treatments used a full factorial combination of temperature (7 and 11°C) and pCO2 (400 and 800 ppm) treatments. Results suggest that changes in pCO2 and temperature had both individual and interactive effects on phytoplankton species composition and elemental stoichiometry. Warming mainly favored the accumulation of picoplankton and dinoflagellate biomass. Increased pCO2 significantly increased particulate organic carbon to particulate organic phosphorus (C:P) and particulate organic carbon to biogenic silica (C:BSi) ratios, and decreased total diatom abundance; in the meanwhile, higher pCO2 significantly increased the ratio of centric to pennate diatom abundance. Warming and increased pCO2 both greatly decreased the proportion of diatoms to dinoflagellates. The highest chlorophyll a biomass was observed in the high pCO2, high temperature phytoplankton assemblage, which also had the slowest sinking rate of all treatments. Overall, there were significant interactive effects of increased pCO2 and warming on dinoflagellate abundance, pennate diatom abundance, diatom vs. dinoflagellates ratio and the centric vs. pennate ratio. These findings suggest that future ocean acidification and warming trends may individually and cumulatively affect coastal biogeochemistry and carbon fluxes through shifts in phytoplankton species composition and sinking rates.

The rise to dominance of lanternfishes (Teleostei: Myctophidae) in the oceanic ecosystems: a paleontological perspective

Lanternfishes currently represent one of the dominant groups of mesopelagic fishes in terms of abundance, biomass, and diversity. Their otolith record dominates pelagic sediments below 200 m in dredges, especially during the entire Neogene. Here we provide an analysis of their diversity and rise to dominance primarily based on their otolith record. The earliest unambiguous fossil myctophids are known based on otoliths from the late Paleocene and early Eocene. During their early evolutionary history, myctophids were likely not adapted to a high oceanic lifestyle but occurred over shelf and upper-slope regions, where they were locally abundant during the middle Eocene. A distinct upscaling in otolith size is observed in the early Oligocene, which also marks their earliest occurrence in bathyal sediments. We interpret this transition to be related to the change from a halothermal deep-ocean circulation to a thermohaline regime and the associated cooling of the deep ocean and rearrangement of nutrient and silica supply. The early Oligocene myctophid size acme shows a remarkable congruence with diatom abundance, the main food resource for the zooplankton and thus for myctophids and whales. The warmer late Oligocene to early middle Miocene period was characterized by an increase in disparity of myctophids but with a reduction in their otolith sizes. A second and persisting secular pulse in myctophid diversity (particularly within the genusDiaphus) and increase in size begins with the “biogenic bloom” in the late Miocene, paralleled with diatom abundance and mysticete gigantism.

Diatom Diversity on the Skin of Frozen Historic Loggerhead Sea Turtle Specimens

In recent years, biofilm-forming diatoms have received increased attention as sea turtle epibionts. However, most of the research has focused on carapace-associated taxa and communities, while less is known about diatoms growing on sea turtle skin. The current study investigated diatom diversity on the skin of loggerhead sea turtle heads detached from the carcasses found along the Adriatic coast between 1995 and 2004 and stored frozen for a prolonged period of time. By using both light and scanning electron microscopy we have found diatom frustules in 7 out of 14 analysed sea turtle samples. Altogether, 113 diatom taxa were recorded, with a minimum of seven and a maximum of 35 taxa per sample. Eight taxa, Achnanthes elongata, Berkeleya cf. fennica, Chelonicola sp., Licmophora hyalina, Nagumoea sp., Navicula sp., Nitzschia cf. lanceolata, and Poulinea lepidochelicola exceeded 5% of relative abundance in any one sample. The presumably obligately epizoic diatom taxa, A. elongata, Chelonicola sp., and P. lepidochelicola, dominated in six loggerhead samples, contributing up to 97.1% of the total diatom abundance. These observations suggest that on the sea turtle skin highly specialised taxa gain even greater ecological advantage and dominance over the co-occurring benthic forms than in the carapace biofilms. The suitability of frozen sea turtle skin specimens for diatom analysis and limitations of this approach are discussed.

EFFECT OF PARTICLE SIZES AND CONTENT OF ORGANIC MATTER SEDIMENT ON EPIPELIC DIATOM ABUNDANCE IN BAYUR BAY WATERS OF WEST SUMATERA

The aim of this study is to determine the water quality, the particle size (mm) and the organic matter content sediment, the type and abundance of epipelic diatoms, and the effect of particle size and organic matter content of the sediment on the abundance of epipelic diatoms at Bayur Bay Waters. This study was conducted in June - July 2019. The survey method was applied in this study and sampling location determine by purposive sampling. The resullt of measurement of water quality parameter ranged salinity 29 ‰ - 34 ‰, pH 7-8, current speed of 0,10 m/s – 0,53 m/s, temperature 30,330C - 31,670C. The sediment types are grouped into four types, namely gravel, sandy gravel, gravelly sand, and sand. The average of particle size (Mz) ranged -1,37 Ø - 0,80 Ø. The organic matter on sediment ranged 2,46% -6,36%. Eleven species of epipelic diatoms was recorded namely Amphora sp, Cocconeis sp, Diploineis sp, Halamphora sp, Melosira sp, Navicula sp, Nitzschia sp, Pinnularia sp, Stephanodiscus sp, Isthmia sp and Synedra sp. The average value of abundance range 2.836 – 10.812 ind/cm2. Epipelik diatom abundance was not significantly different between the stations. The effect of sediment particle size on the abundance of epipelic diatoms by 34,37%. The effect of content of organic matter sediment on abundance of epipelic diatoms in Bayur Bay Waters by 51,78%.

ANALYSIS CONCENTRATION OF SURFACTANT ANIONIC AND THE RELATION WITH DIATOM ABUNDANCE IN BUNGUS WATER, PADANG WEST SUMATERA

This research aims to analyze surfactant anionic concentration and diatom abundance that has been implemented at May 2018 in Bungus rivers, Padang. This Research were conducted in survey method, four station were eshtablished with three replication of each sampling station. Analysis of surfactant anionic and diatom content was done at Chemistry Oceanography Laboratory and diatom identification was performed at Biology Oceanography Laboratory. The results showed that surfactant content in the waters ranged from 0,309-0,773 ppm and diatom abundance based on laboratory test on ranged 40,7407-81,4815 Ind/l. The correlation of surfactant and diatom content in waters by using linear regression y = Y = 94.56 -66.8x with correlation coefficient r = 0,809 and correlation water quality parameters with diatom abundance by using multiple linear regression Y= 787,189 -238,828X1 -9,032X2 -6,185X3 +5,371X4 +303,081X5 -35,631X6 with determination regression 0,995 and correlation coefficient r = 0,997.

Spatial links of phytoplankton abundance and community structure between shelf and slope waters off Oregon, USA

Coastal upwelling is known for inducing nearshore primary production, which can be advected to the offshore environment through offshore Ekman transport. However, this nearshore−offshore phytoplankton link has been less characterized at the community level. This study focuses on two shelf and slope sites off Oregon during years of 2013−2017 to examine the shelf−slope covariations in diatom and dinoflagellate abundance and community structure at seasonal and annual timescales. In general, the temporal changes of diatom and dinoflagellate abundance were coherent between shelf and slope. However, some differences were also noticeable. For example, diatom and dinoflagellate bloom magnitudes were higher in 2017 and 2014 on the shelf, but were higher in 2014−2016 at the slope. Diatom abundance had a stronger shelf−slope correlation than dinoflagellate correlation particularly in spring. The community structure was significantly correlated between shelf and slope during the annual upwelling period and in spring season. Ekman transport and nutrients played a significant role in shaping the diatom abundance and community structure temporal patterns at the slope. This shelf−slope correlation study infers that the benefits of nearshore upwelling blooms to the offshore food chains are season dependent and under high interannual variability.