Amplifying Voices Webinars 2022

Amplifying Voices Webinar Series

The ASLO Early Career Subcommittee is pleased to invite you to our webinar series, “Amplifying Voices: Early Career Researchers Making Waves in Aquatic Sciences.” This webinar series promotes the exciting work of early career aquatic scientists from underrepresented groups in our global community. The series features presentations from early-career researchers. In each session, the presenters share their work in 20-minute presentations followed by a moderated Q+A. The presentations are free to the public.

Webinars are presented each month and are recorded. The videos are uploaded to ASLO's YouTube channel and are freely available for viewing.

2021 2023

2022 Webinars

January 27, 2022
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Speakers:

Justyna Hampel
Department of Ecology, Environment and Plant Sciences, Stockholm University, Sweden

Microbial communities respond predictably to built habitats on the seafloor

Presentation Abstract

Ocean seafloor is a complex ecosystem where habitat heterogeneity is one of the major factors influencing biodiversity. Widespread natural, geological features like hydrothermal vents and seeps create unique environments and select for unique populations of micro and macrofauna. In contrast, artificial habitats are understudied but might play equally substantial role in shaping biodiversity, community composition, and ecosystem function. Built habitats on the seafloor are increasing as the consequence of ocean sprawl however, they pose unknown effects on benthic communities. This study addresses the impact of model built environment, shipwrecks, on microbial diversity and microbiome structure in surrounding sediment. We report elevated microbial diversity and unique but uniform core microbiome in sediments around shipwrecks. We show that the ‘sphere of influence’ of these built habitats extends up to 200-300 m onto the seafloor. Supervised learning techniques made strong predictions of proximity to the structure based on archaeal and bacterial ASV. Notably, response of archaeal communities to built features was more pronounced than in bacteria. Core microbiome of archaea surrounding the shipwrecks was enriched in distinct communities not present at further distances. The strongest predictions of proximity to shipwrecks were in closest (2-9m) and furthest (1000 m) distance groups. We show that built habitats, although much younger than natural features, have similar effects on microbial diversity and community structure in marine deep biosphere and shape the microbiome in a predictable way. These findings are critical in learning how built habitats affect microbial communities in the global ocean in the Anthropocene.

Kuo Hong Wong (Josh)
College of Science and Engineering, Kanazawa University, Japan

Origin of the zinc-silicate decoupling in the subarctic Pacific

Presentation Abstract

Dissolved zinc (dZn) and silicate (Si) have similar distribution profiles in the global ocean. This coupling of distribution is baffling because the remineralization of Zn and silicate occurs at different timescales, with Zn regenerated at shallower depths than Si. In the Southern Ocean, however, strong vertical mixing of water masses homogenizes the distributions of dZn and Si, which are then transported to the other ocean basins via the ocean conveyor belt. An exception is the subarctic Pacific, where dZn and Si decouple. To investigate this anomaly, we determined the dZn and Si distributions in the subarctic Pacific (GEOTRACES GP02 line), Gulf of Alaska, and the western Bering Sea. These regions are high nutrient low chlorophyll regions with very low surface dissolved iron (dFe) concentrations (< 0.1 nM). Our data reveal increased uptake of dZn by phytoplankton in coastal regions where supplies of dFe from terrestrial sources alleviate Fe limitation. Hence, the resulting sinking particles have high Zn content. Subsequent remineralization releases Zn at shallower depths than Si but unlike in the Southern Ocean, the absence of vertical mixing processes prevents the homogenization of dZn and Si. Strong advective fluxes from the coastal regions to the subarctic Pacific transport intermediate water with a high dZn/Si ratio and cause distortion to the globally homogenous dZn and Si distribution. dZn/Si ratio decreases away from the coastal regions as water mass mixing weakens this anomaly. This propagation pattern is consistent with that of dissolved manganese, which is used to trace water mass originating from coastal regions.

February 24, 2022
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Speakers:

Arkaprava Mandal
Indian Institute of Science Education and Research Kolkata, India

Tracking the ecological health of a coastal ecosystem from the North-East Bay of Bengal- Applicability of benthic foraminifera as bioproxy

Presentation Abstract

Since the beginning of the industrial revolution in the mid-18th century, climate change has become a topic of increasing concern. The present study has been done in marginal environment of Junput, West Bengal, India adjacent to the northeast Bay of Bengal. This study site was once part of mangrove vegetation, but now hardly mangrove left. The site shelter quite a few endangered species like the horseshoe crab, olive ridley turtle, and fiddler crab, but now this area has degenerated into the densely populated coastal zone and become a reputed fishing zone. In order to learn the present stressed condition of the studied area and predict how these stresses might evolve in the near future, it requires testate marine organisms like benthic foraminifera. Benthic foraminifera are well preserved in the sediments and sensitive to changes in environmental conditions. The present study investigates the applicability of this group to track the climatic change in the study area. The study encompasses a number of sampling points from intertidal area representing hydrodynamic gradients within the freshwater-influenced ecosystem. The present study reveals benthic foraminifera diversity and abundance were overall low, and the assemblage dominated by calcareous species. The calcareous species Ammonia spp., Asterorotalia trispinosa, Quinqueloculina sp., Globigerinoides sp., and agglutinated species Trochammina inflata were observed. The presence of only three calcareous taxa and almost absence of agglutinated taxa indicate the degradation of ecological quality of the coastal Bay of Bengal. Apart from optimally preserved tests, many broken tests were observed. The broken tests were probably the result of mechanical damage or indicating the taphonomic alteration in intertidal sediment. The dominance of populations of Ammonia spp. across studied sites indicating shreds of evidence of increasing anthropogenic stress. However, the generated data set can be compared to similar marginal marine environments globally to developing an environmental proxy for future tracking of the prevailing environmental conditions of the coastal environment.

Chakresh Kumar
Indian Institute of Science Education and Research Kolkata, India

Seasonal dynamicity of environmental variables and water quality index in the lower stretch of the River Ganga

Presentation Abstract

Rapid increase in industrialization and urbanization has resulted in unbalanced release of sewage and pollutants into the River Ganga. Unrestricted and unchecked discharge of both municipal and industrial waste has resulted in considerable deterioration of water quality along the entire course of the river and specifically along the lower stretch that flows through the state of West Bengal before opening into the Bay of Bengal. The lower stretch, also referred to as Bhagirathi-Hooghly records much higher coliform count and dissolved nutrients which renders the surface water unfit for usage. Sites including the heavily populated suburban sites of Kalyani, Tribeni, Halisahar, Naihati, Chandannagar, Palta, Barrackpore,Dakshineswar and Kolkata were monitored seasonally to understand the rapidly changing water quality. Samples were classified into point sources (PS)- areas of direct discharge of municipal wastes and surface water (SW)- areas away from the direct influence of the point source. Water samples were collected from PS and SW over pre-monsoon (March-June), monsoon (July- October) and post-monsoon (November- February) seasons of 2019. In-situ environmental parameters including surface water temperature, dissolved oxygen, pH, salinity, total dissolved solids (TDS) and electrical conductivity (EC) were measured in triplicates during time of sampling. Both pH and DO were found to be strongly influenced by seasonal precipitation and in turn affected the water quality. Dissolved nutrients including nitrate and o-phosphate concentration showed significant seasonal variation. Relatively higher concentration of dissolved nutrients in the PS stations compared to the SW stations indicated the possible release of municipal and industrial waste directly into the river. Increase in nutrient concentration in turn strongly influenced environmental parameters including pH, DO and EC. Variations in these four parameters, including pH, DO, EC and dissolved nitrate indicated very bad water quality along most sampled sites. Water quality index provided comprehensive insights into the condition of the surface water. Along with a strong seasonal influence, WQI indicated that surface water from most of the sampled stations were unfit for usage.

Special Session, March 17, 2022
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Speakers:

Leslie Townsell
ASLO DEIJ Intern

An Introduction and Tour of the ASLO Diversity, Equity, Inclusion, and Justice Forum

Anwesha Ghosh
ASLO Early Career Committee Member

Putting things into perspective - a story of the changing face of the Indian Sundarbans

March 31, 2022
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Speakers:

Ahmed Mohammed Nazem Elsayed Elreedy
Institute of Technical Microbiology, Hamburg University of Technology, Germany

Innovations in bio-electrochemical systems as a powerful "waste-to-energy" tool

Presentation Abstract

Anaerobic biological treatment of saline phenolic wastewater has some limitations such as slow adaptation, low biodegradability, and salinity-derived washout of biomass, though this technology has some benefits in terms of bioenergy recovery, simplicity in operation, and economic rationality. Therefore, we propose a packed-bed circular baffled reactor (PB-CBR) along with a co-metabolism strategy for phenol adaptation at a salinity level of 10 g-NaCl/L. Phenol and glucose were gradually increased and decreased to 0.9 and 1.0 g/L, respectively. Stable and efficient performance was achieved with > 99.9% phenol removal, ~98% overall biodegradability, and ~ 0.3 L CH4/gCOD. A sudden increase in phenol to 2 g/L was then examined, where phenol removal dropped to ~ 19% after 30 d; after another 30 d, the removal was negligible even when phenol was decreased to 1.7 g/L. The compartment-wise analysis of PB-CBR showed that phases-separation, along with all compartments, maintained the overall efficiency, particularly when facing salinity or phenol shocks; otherwise, earlier compartments achieve ~ 95% of efficiency. The microbial community analysis showed that Corynebacteriaceae, Syntrophaceae, Kosmotogaceae, and Synergistaceae were key players in phenol-degradation. Using readily biodegradable co-substrate enhanced biodiversity. Eventually, and according to a cost-benefit analysis, the present work offers a promising opportunity to treat phenol-based saline effluents in an efficient, sustainable, and affordable way.

Fousiya Aa
Department of Earth Sciences, Indian Institute of Technology, Kanpur, India

Marine calcifiers as timekeepers: Monsoonal variability and ocean surface temperature reconstruction

Presentation Abstract

Marine calcifiers are the most important components of the marine ecosystem that grow in the Tropical Oceans. They are widely known as the best archives to provide high-resolution records of ocean atmospheric variabilities on sub seasonal resolution spanning up to a few hundred years. Signatures preserved in these organisms are known to provide useful information and reconstruction of Sea Surface Temperature (SST), Sea Surface Salinity (SSS), upwelling intensity, oceanic circulation etc1. Lakshadweep Islands in the north Indian Ocean harbour various types of such calcifiers and various workers have recently studied them for paleoclimatic/paleo-environmental reconstruction. However, the atmospheric CO2 rise during the post-industrial era has resulted in a decrease of ~0.1 unit in surface ocean pH, a process commonly known as Ocean Acidification (OA)2, which has highly threatened the growth and existence of these marine calcifiers . In this talk, I will shed light on the significance and resilience of Corals and Giant Clam shells (two important marine calcifiers) growing under large variability in physical and biological processes in a strongly upwelling region of the Tropical Indian Ocean. Our preliminary records reveal that even short high temperature events could significantly perturb the biology of marine calcifiers and require long recovery phases. These results are particularly significant for conservation efforts of some of the most endangered marine calcifiers growing in regions in with on-going global warming trends.

April 28, 2022
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Speakers:

Radhika Bhargava
Department of Geography, National University of Singapore

Previous shoreline dynamics determine future susceptibility to cyclone impact

Presentation Abstract

Extreme weather events are a cause of mangrove forest loss and degradation globally. Almost half of the world’s mangroves are found in the tropical cyclone belt, and forests often experience disturbance in structure, functioning and ecosystem service provision. Understanding the factors that increase the vulnerability of mangroves to such disturbances is a challenge. Using a novel remote sensing analysis combining water class change with vegetation classification, we showed that mangrove loss across multiple cyclone events is influenced by previous erosion history, suggesting that the prior state of the coastline affects susceptibility to future disturbance events. During Cyclone Amphan in May 2020, more than 1200 km2 of mangroves were damaged and 40.6 km2 of shoreline was lost. Cyclone Amphan caused the most damage out of 3 recent cyclones, with the most mangrove loss (18.8%) experienced along shorelines that were eroding over the past 35 years. This can be explained by the long-term effect of erosion on the overall intertidal morphology of the shoreline. Landscape-scale mangrove management, particular of sediment budgets is essential in order to switch previously eroding mangroves to a state where they can withstand cumulative storm impacts.

Saumya Silori
Biological Oceanography Division, CSIR-National Institute of Oceanography (India)

Contrasting phytoplankton and biogeochemical functioning in the eastern Arabian Sea shelf waters recorded by carbon isotopes

Presentation Abstract

This study examines the relationship between the isotopic signature of phytoplankton-derived particulate organic matter (POM) (δ13CPOC) and estimates of growth rate and community composition along a north-south gradient in the western Indian shelf waters which possess contrasting biogeochemistry and mixed layers depths. The Eastern Arabian Sea/western Indian shelf turns highly productive due to the SW monsoon-induced upwelling at its southern region and experiences drastic seasonal reversal. We have characterized the POM pool by quantifying Chla, particulate organic carbon (POC), and particulate nitrogen (PN), C:N ratios, along with δ13CPOC values during the SW Monsoon. The prevailing physicochemical features contrasted between the southern (8◦N to 12◦N) and northern (13◦N to 21◦N) stations. Close couplings between POC, PN, and Chla contents indicated the autochthonous nature of POM. Low temperature, shallow mixed layer depths (MLDs), high concentrations of nutrients, POM, and Chla, marked the upwelling signature in the south. Conversely, relatively higher temperatures, salinity, deeper mixed layers (MLs), lower concentrations of nutrients, POM, and Chla were evident at the northern stations. Five times higher POC concentrations were noticed in the south (65.5 ± 22.0 μmol L−1) than in the north (12.8± 5.4 μmol L−1) within the MLs. Phytoplankton community shift (based on marker pigment analysis) and the δ13CPOC values were closely coupled. The nutrient replete microphytoplankton (diatoms) dominated southern stations were associated with higher values of δ13CPOC (−23.0 ± 2.3‰) which was attributed to faster growth rate; conversely, the oligotrophic nitrogen-limited waters in the north dominated by pico and nanophytoplankton (haptophytes and cyanobacteria), were characterized by distinctly lower δ13CPOC values (−26.6 ± 0.9‰). Phytoplankton growth rates based on a model were consistent with this trend. Our results show that the autochthonous POC is the primary source of organic matter, and the contrasted biogeochemistry-induced phytoplankton communities and their growth rates mostly governed the δ13CPOC variability in this region. However, the lower values in the subsurface waters at the south were likely to be influenced by light limitation and heterotrophy.

May 26, 2022
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Speakers:

Nirupama Saini
Indian Institute of Science Education and Research Kolkata

Investigating the seasonal abundance and distribution pattern of microplastics in a Mangrove ecosystem of northeastern coastal Bay of Bengal

Presentation Abstract

Other than the bigger pieces of the plastics, the plastic pieces of size smaller than 5mm, also termed as microplastics, are being recognized as one of the global problems. This study aims to investigate the abundance and composition of microplastics in surface water of the westernmost part of Sundarbans, during monsoon and post-monsoon seasons to better understand the seasonal variations and determine the source of microplastic pollution and its migration features. The world's largest contiguous mangrove forest, Sundarbans, is a UNESCO world heritage site and a Ramsar site. Sundarbans is shared between Bangladesh and India, which are among the top mismanaged plastic waste generating nations and are discharging plastic waste downstream through rivers and coasts, making the Sundarbans a cesspit for plastic waste. Moreover, this mangrove ecosystem is formed by the super confluence of the Ganga, Brahmaputra, and Meghna rivers. These rivers are among the top ten plastic waste carriers and combined flow of them can discharge up to 3 billion pieces of microplastics per day into the Bay of Bengal. The microplastic abundance varied from 3items/liter to 66 items/liter with a mean abundance of 22.27±11.8 in monsoon; from 3items/liter to 34items/litre with a mean abundance of 14.52±7.97 in post-monsoon. Overall, fibers were predominant and constituted around 58 percent of total microplastics. Based on color, colorless and white microplastics are more in number. Spectroscopic analysis revealed polypropylene as the most abundant type of polymer. The study provides the preliminary knowledge regarding the microplastic pollution in Sundarbans which can be further utilized in understanding its long-term implications on the ecosystem.

June 30, 2022
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Speakers:

Richard Mugani
PhD Student
Cadi Ayyad University, Faculty of Sciences Semlalia, Marrakech, Morocco

Impact of microcystins on the dynamics of the rhizosphere microbiota: a focus on extra- and intracellular microbial enzymatic activities

Presentation Abstract

Cyanobacterial blooms have become a global threat due to toxins released into water bodies. These cyanobacteria-contaminated waters are used in agriculture without treatment. Nevertheless, effects of these cyanotoxins on aquatic and soil microbiota are not fully understood. This study investigates how these cyanotoxins affect the microbial activity of water and soil by measuring the microbial activities of key enzymes involved in biogeochemical cycles. Four enzymes were analyzed by the fluorometric method using MUB- linked substrates: arylsulfatase (ARS), β-glucosidase, N-acetylglucosaminidase (NAGase), phosphatase, and three others were quantified by colorimetry: dehydrogenases, proteases, and urease. Three Bacterial strains previously isolated in bloom colonies, water, and soil highly contaminated with cyanotoxins were inoculated into 48 soil pots, from which 24 soil had been sterilized and 24 not sterilized. These pots, placed in the greenhouse, contained pea plants in 5 replicates and were irrigated for three months with 0, 50, and 100 µg/L MC-LR. Finally, the soils were collected, and the soil's enzymatic activities and chemical properties were analyzed, including loss on ignition (LOI), total phosphorus, and carbon/nitrogen/sulfur analysis by combustion (NCS). The results obtained showed a significant difference in the decrease of all enzymatic activities when irrigating with high MC-LR concentration. Bacterial inoculation showed increased enzyme activities when triple bacterial inoculation was applied. Similarly, there was a positive correlation between bacterial inoculation and total phosphorus concentration and NCS. Our results indicate that MC -LR diminishes soil microbial activities. However, inoculation of soil with cyanotoxin-tolerant bacteria seems to counteract the adverse effects of these pollutants.

Archana Tiwari
Diatom Research Laboratory, Amity Institute of Biotechnology, Amity University, Noida, India

Role of Diatom Algae in carbon dioxide mitigation and generation of high value products

Presentation Abstract

The increasing impact of climatic change has severely influenced all the living organism on earth. Algae are among the opaquest photosynthetic microorganism found in oceans, rivers, and freshwaters and they play a major role in reducing global warming as they fix more than 25% of atmospheric carbon-dioxide. They are a reservoir of untapped potential with the multifaceted application including carbon-dioxide mitigation, vital role in the aquatic food web as primary producers, wastewater remediation by quenching pollutants originating from diverse sources like industries, agricultural and human sources. Despite their abundance and diversity in nature, few species are currently used for biotechnologically applications. Diatom Biorefinery has gained importance in recent years as more and more algae are identified and explored as a source for lipids, pigments, and other biomolecules. The diatom biorefinery involves exploiting the diverse roles of diatoms in carbon-dioxide mitigation and generation of high amount of lipids with EPA and DHA, fucoxanthin, and other active molecules with immense potential as new-age drug molecules and providing sustainable solutions towards a circular economy.

July 28, 2022
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Speakers:

Dr. Prasun Goswami
National Institute of Ocean Technology (NIOT), Atal Centre for Ocean Science and Technology for Islands, Ministry of Earth Sciences, Govt. of India

Plastic pollution and beyond: do microbes hold the key towards a sustainable solution to this global crisis?

Presentation Abstract

Plastic is a wonder product, though, significant concerns arise about plastic leakage to the environment. Tiny plastic particles, so-called microplastics (MP), have been detected ubiquitously. They are bioavailable for many organisms and may cause negative effects. The present study was conducted at first to understand the nature, behavior, and interactions of microplastics in the marine environment. We compared microplastic levels in the Andaman Sea and the Arabian Sea and found, that MP levels at the Arabian Sea were significantly higher than in the Andaman Sea. Further, to understand food web MP interaction, we analyzed MP ingestion rates in marine zooplankton communities. Clear evidence of a high amount of MP ingestion was observed in zooplankton. Food chain transfer of MPs in some commercially important carnivorous fishes was also noticed. Polyethylene and polypropylene are the most common polymer types detected. These MP polymers get quickly colonized by a wide range of microorganisms, through biofilm development, which is known as the "plastisphere." The plastic degradation potential of these ‘plastisphere’ associated microbes was assessed. Based on our preliminary screening we prepared a bacterial consortium using four highly potential LDPE utilizing bacteria and incubated with LDPE for 120 days. After 120 days on average, nearly 47% LDPE degradation was observed. These results suggest that the bacterial consortia used in this work have great potential to degrade plastics and solve the problem. However, further research is required to develop innovative, cutting-edge, and eco-friendly technology to solve plastic pollution.

Ms. Diksha Sharma
CSIR-National Institute of Oceanography, Biological Oceanography Division, India

Impacts of Zn and Cu enrichment under ocean acidification scenario on a phytoplankton community from tropical upwelling system (Arabian Sea)

Presentation Abstract

Increasing dissolution of CO2 in the surface ocean is rapidly decreasing its pH and changing carbon chemistry which is further affecting marine biota in several ways. Phytoplankton response studies under the combination of elevated CO2 and trace metals are rare. We have conducted two consecutive onboard incubation experiments (R. V. Sindhu Sadhana; August 2017) in the eastern Arabian Sea (SW coast of India) during an upwelling event. A nutrient enriched diatom bloom was initiated onboard and grown under ambient (approx. 400 μatm, A-CO2) and high CO2 levels (approx. 1000 μatm; H–CO2) with different zinc (Zn; 1 nM) and copper (Cu) concentrations (1 nM, 2 nM and 8 nM). Phytoplankton community composition and the dominant genera were different during these two experiments. CO2 enrichment alone did not show any significant growth stimulating impact on the experimental community except enhanced cell density in the first experiment. Addition of Zn at A-CO2 level revealed no noticeable responses; whereas, the same treatment under H–CO2 level significantly reduced cell number. Considerably high protein content under H–CO2þZn treatment was possibly counteracting Zn toxicity which also caused slower growth rate. Cu addition did not show any noticeable impact on growth and biomass production except increased protein content as well as decreased carbohydrate: protein ratio. This can be attributed to relatively higher protein synthesis than carbohydrate to alleviate oxidative stress generated by Cu. The centric diatom Chaetoceros and toxin producing pennate diatom Pseudo nitzschia showed no significant response to either CO2 or Zn enrichment. Large centric diatom Leptocylindrus and Skeletonema responded positively to Zn addition in both CO2 levels. The former species showed the most sensitive response at the highest Cu and H–CO2 treatment; whereas, the pennate diatoms Nitzschia and Pseudo-nitzschia (toxigenic diatom) showed higher resilience under elevated CO2 and Cu levels. This observation indicated that in future ocean, increasing CO2 concentrations and trace metal pollution may potentially alter phytoplankton community structure and may facilitate toxigenic diatom bloom in the coastal waters.

August 25, 2022
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Speakers:

Shailesh S. Nair
Postdoctoral Researcher
Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Science

Decoding the mechanisms behind the recurrent mutualism between marine Synechococcus sp. PCC7002 and heterotrophic bacterial community despite environmental interference under long-term coexistence

Presentation Abstract

Marine algae are rightly called the “lungs of the sea”. They produce approximately 70 % of the oxygen that sustains life on earth and regulates the marine primary productivity on which the whole marine life is sustained. Among these algae, picocyanobacteria (mainly Prochlorococcus and Synechococcus) are the most abundant group, contributing up to 60% of the carbon fixation in the oceans and 30% of the global primary production. On the other hand, marine heterotrophic bacteria convert the organic matter derived from marine life (including algae) into inorganic nutrients. These inorganic nutrients in turn support the growth of marine algae. However, most of the open ocean is poor in these nutrients. Despite, this Prochlorococcus and Synechococcus can thrive in such nutrient-poor regions. In this work, we show that Synechococcus and associated heterotrophic bacterial communities tend to move towards mutualistic relationships on long-term coexistence by undergoing bacterial community succession. Once the mutualistic relationship is established, the bacterial generation of essential nutrients (especially nitrogen) supports the long-term, healthy growth of Synechococcus. Furthermore, we show that environmental factors such as the provision of external nutrients disrupts their established mutualism. However, once the effect of external environmental influence is weakened, they re-established the disrupted mutualism under long-term coexistence. Using modern methodologies such as metagenomics, metatranscriptomics and 15N isotopic nitrogen fixation analysis, we reveal that the associated bacterial nitrogen fixation triggered the re-establishment of mutualism. During this process, bacterial community structure and functions underwent tremendous adjustments to achieve the driving effect, and a co-generation of nitrogen, phosphorus, iron and vitamin by the heterotrophic bacteria sustained Synechococcus’s prolonged healthy growth. Our findings suggest that Synechococcus and heterotrophic bacteria may have an inherent tendency towards mutualism despite environmental interference. This may exhibit their co-evolutionary adaptations in nutrient-deficient environments.

Caroline Ganglo
PhD Candidate
University of Koblenz-landau Systemlink

Chironomids reduction alters carbon dynamics in ponds

Presentation Abstract

Shallow lentic aquatic ecosystems are important repositories of organic carbon and hotspots of carbon cycling and greenhouse gas emissions. Tube-dwelling invertebrates, such as chironomids, can be key players in C processing in these water bodies, yet their effect on C cycling at ecosystem scale are largely unknown. We tested whether a 41% reduction in chironomid abundance and a shift in benthos community, found after application of the biocide Bacillus thuringiensis israelensis (Bti), have implications for C fluxes, pools, and organic matter decomposition. Data were collected over one year in shallow and deep habitats of 12 experimental floodplain pond mesocosms (FPMs), half of them treated with Bti. C fluxes were measured as CO2 and CH4 evasion, and as emerging merolimnic insects. C pools were measured as dissolved inorganic and organic C in surface and pore water, as well as organic C in sediment, plants and macroinvertebrates. We further estimated organic matter decomposition from tea bag incubations. The fluxes, pools and decomposition rates varied seasonally and differed systematically between different habitats of the ponds. In ponds treated with Bti, for which an increase of CH4 evasion has been reported, we found lower concentrations of dissolved organic C in surface water, while all remaining pools, fluxes, and rates were unaffected. These results suggest a rather partial influence of changes in macroinvertebrate communities caused by Bti application on C cycling in FPMs ecosystems, yet they confirm the existence of long-lasting effects on selected components of C budgets.

September 29, 2022
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Speakers:

Breylla Campos Carvalho
Technician/Early Career Researcher
Center for Marine Biology (CEBIMar) of University of São Paulo, Brazil

Spatio-temporal variability of water quality in tropical reservoirs from Landsat satellite images

Presentation Abstract

Reservoirs are aquatic environments with complex interactions between bio-chemical and physical components. Many of those parameters can be estimated from remote sensing tools, especially since nowadays increasing technological progress allows the analysis of these environments in high spatial and temporal resolutions. This work aimed to analyse the water quality of four reservoirs located in the centre-south region of Brazil from bio-optical and thermal water parameters. To this end, hundreds of Landsat 5 (TM), 7 (ETM+) and 8 (OLI) satellite images were processed by the Google Earth Engine cloud computing platform to estimate chlorophyll-a density (chl-a), Secchi depth (SD), trophic state index (TSI) and water surface temperature (WST). To calibrate the equations, eleven monitoring points were used – from state environmental agencies and a research project carried out in one of the reservoirs – in twenty-seven scenes from the TM and ETM+ sensors and thirty from the OLI sensor, with the interval between the monitoring date and image taking being no more than six days. Additionally, records from two weather stations near the reservoirs were analysed to evaluate meteorological influences on water parameters. The results show that in three reservoirs TSI is influenced mostly by SD, while in the fourth one chl-a density worked better as a proxy for TSI. Air temperature, rainfall and global radiation are the meteorological parameters that correlate significantly with the bio-optical and thermal water parameters. The spatial and temporal variations found allowed regionalizing the reservoirs, serving as an important tool for the management of water resources in the region.

Alejandra Correa Bedoya
MSc. In Applied Aquatic Ecology for Sustainability
University of Antioquia, Colombia

Bioindication: a methodology for the calibration of the BMWP Biological Monitoring Working Party system in the Andean region of Colombia

Presentation Abstract

The development of standard scoring systems for assessing the water quality of freshwater ecosystems are a high priority need for water resource management. The Biological Monitoring Working Party (BMWP) score system is a worldwide standard methodology used to assess water quality using benthic macroinvertebrates in rivers and streams. Although the BWMP was developed for temperate zone systems, it has been largely copied and applied for bioassessment in other regions globally, including Colombia. Despite its application in Colombia, it has not been biogeographically adapted, nor calibrated.

In this study, I present the adaptation and calibration of the BMWP score system for the economically significant Andean region of Colombia. A database with a total of 39,282 records of aquatic macroinvertebrates and water quality variables was compiled. The dataset was sub-divided by catchment: Magdalena, Cauca, Medio-Magdalena and Nechi. Magdalena and Cauca catchments were used for the development of the proposed methodology. Medio Magdalena and Nechi were set to be the databases for the validation of the method. The methodology was based on the dependence of macroinvertebrates on dissolved oxygen (mg/l) concentration. Oxygen tolerance was used as a main determinant for scoring of macroinvertebrate taxa sensitivities. Results of the introduced methodology reflect a wider distribution of the tolerance scores. As a part of the validation procedure, this research presents the derivation of biological bands classification as a multimetric tool for the assessment of ecological status in Andean freshwater ecosystems. The biological bands compiled the BMWP total score as a function of ASPT (average score per taxon) and categories of rarity of taxa. Overall, this study constitutes the first attempt using multivariate and multimetric methods for the regional calibration of the BMWP score system in Colombia.

October 27, 2022
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Speakers:

Frank Akamagwuna
Postdoctoral Fellow
Institute for Water Research, Rhodes University, South Africa

Macroplastic proliferation in river systems: Can they support the establishment of macroinvertebrates and emerging pathogens?

Presentation Abstract

Macroplastics are ubiquitous in the environment and have been recognised as one of the leading causes of aquatic ecosystem deterioration. Recently plastics in freshwater ecosystems have been shown to form artificial microhabitats in rivers and streams, affecting the natural characteristics of stream habitats and community structure. However, the biological colonisation of artificial macroplastic habitats and its effects on macroinvertebrate distribution in freshwater ecosystems has not been adequately investigated. In this study, we examine the potential for macroplastics to support the establishment and colonisation of macroinvertebrates and emerging pathogens in selected rivers in the Eastern Cape Province, South Africa. A field-based colonisation experiment was conducted in four headwater streams in the Eastern Cape Province, South Africa. Plastic materials and natural substrates were classified into three substrate types: Natural substrate, Natural + Plastic substrate, and Plastic dominated substrate. The three substrate types represented a gradient of plastic habitat. The substrates were deployed into stream hydraulic habitats, including riffles, run and pools, for 180 days. Preliminary results showed that macroinvertebrates exhibited taxa-specific colonisation of plastic materials between the substrate types and deployment periods. The colonisation of substrates changes significantly across time; however, it did not differ between plastic substrate types in the selected streams. The natural-dominated substrate had the highest relative abundance of macroinvertebrates compared to the Natural + Plastic substrate and plastic-dominated substrates. This colonisation what primarily influenced by the hydraulic biotope types, differing between the biotopes. Overall, the preliminary results provided essential insights into the influence of macroplastics proliferation in stream microhabitats and the distribution of macroinvertebrates. However, further work and analyses are being conducted, including microbial sequencing, to elucidate some of the outcomes biological colonisation of macroplastics.

Ada Acevedo-Alonso
MSc. Carcinologist
Contracting Scientist, Remote Ecologist Inc., Colombia

Conservation Status of the Neotropical Mountain Freshwater Crabs
(Pseudothelphusoidea)

Presentation Abstract

The Neotropical region is recognized as one of the world’s most important biodiversity-rich regions, especially its species-rich montane environments. The superfamily Pseudothephusoidea is principally associated with high-altitude environments and its known as mountain crabs. This family comprises 49 genera and 293 species and is the most threatened group because the freshwater environments in the Neotropics are increasingly threatened. The 2008 IUCN global conservation assessment found 15.5% of the superfamily Pseudothelphusoidea to be threatened with extinction and projected that in the worst-case scenario (if the Data Deficient species when eventually assessed are all in a threatened category), then the number of threatened species would be alarmingly high (72%). The reassessment included more than 40 new species of pseudothelphusids that have been described since the first assessment, together with improved data on ecology, distribution, and threats. More than one-fifth (21.2%) of

Neotropical pseudothelphusoids were found to be threatened with extinction, notably in South America where the threats are all associated with the rapid growth of the human population in montane environments. The principal threats to pseudothelphusids include deforestation, water pollution, and dam construction. Additionally, this study shows the need for more studies on freshwater crab ecology, population trends, and threats that can in turn be used to formulate urgently needed conservation action plans.

December 8, 2022
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Speakers:

Avanti Acharya
PhD Student
University of Calcutta, India

N₂O in the Indian Sundarbans Estuaries - Latest studies

Presentation Abstract

The Indian Sundarbans are a UNESCO world heritage site on biodiversity. Prone to heavy monsoonal rainfall and tidal action, the mangrove vegetation structure accumulates organic materials, which seep into adjacent waters via runoff. Consequent biogeochemical processes there emit biogenic gases like nitrous oxide into the atmosphere from several interfaces. However, no previous account on N₂O exists from the Indian Sundarbans. The present study, hence, emphasized the distribution and dynamics of N₂O in the Indian Sundarbans estuaries on a larger spatial scale. Spatial, temporal variability, controlling factors and fluxes of the gas from various interfaces were studied thoroughly. Finally, a detailed estuarine budget and global warming potential was proposed for N₂O. Exhaustive observations were carried out along the stretch of three major estuaries - the Saptamukhi, Thakuran, and the Matla. The studied estuaries showed similar hydrographical settings. Seasonal mean dissolved inorganic nitrogen concentrations were directly associated with estuarine N₂O which was maximal in the monsoon. Seasonal mean dissolved inorganic nitrogen concentrations were directly associated with estuarine N₂O which was maximal in the monsoon, implying nitrification. N₂O concentrations (saturations) were up to 74.4 nM (1286 %) alongside advection of N₂O-enriched waters of riverine origin. Despite occasional undersaturation, the estuaries were a net source of atmospheric N2O throughout the year and emitted about 0.8 Gg N₂O yr^-1 (0.5 Gg N-N₂O yr^-1). Our study puts forth the need for regular monitoring of N₂O as a climate-relevant trace gas as its emissions from coastal areas are a major contribution to the global atmospheric N₂O budget.

Dr. Isa Elegbede
Geo Blue Planet/Lagos State University, Ojo, Switzerland/Lagos, Nigeria

Ocean and coastal data inclusivity for sustainable development in Africa

Presentation Abstract

The global decade of action has extensively elaborated its mandate toward achieving overboard sustainability for the ocean and coastal resources. Thus, exploring inclusiveness for scientists and traditional citizen scientists, including some other relevant stakeholders, would be necessary to overcome these resources' issues. Likewise, inclusivity in the contest of this presentation would discuss and seek possibilities for partnership and collaborations between the global north and global south. Furthermore, this research will also consider working with additional scientists with historical and natural knowledge of the start of the art in the ocean and coastal science.

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