Impact of water column stability dynamics on the succession of plankton food web types in the offshore area of the Adriatic Sea

Šolić, Mladen; Šantić, Danijela; Šestanović, Stefanija; Bojanić, Natalia; Grbec, Branka; Jozić, Slaven; Vrdoljak, Ana; Ordulj, Marin; Matić, Frano; Kušpilić, Grozdan; Gladan, Živana Ninčević

doi:10.1016/j.seares.2020.101860

Cited by 14 publications

(4 citation statements)

References 84 publications

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“…The Middle Adriatic Sea is generally considered as an oligotrophic (low-production) ecosystem in which picophytoplankton accounts for a large portion of the total plankton biomass [31,32]. Our results fit well into that consideration, indicating a significant role of picoplankton size fraction in the microbial food web.…”

Section: Discussionsupporting

confidence: 83%

Extracted Spectral Signatures from the Water Column as a Tool for the Prediction of the Structure of a Marine Microbial Community

Puškarić,

Sokač,

Ninčević

et al. 2024

JMSE

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In this communication, we present an innovative approach leveraging advanced Machine Learning (ML) and Artificial Intelligence (AI) techniques, specifically the Non-Negative Matrix Factorization (NMF) method, to analyze downward and upward light spectra collected by Hyperspectral Ocean Color Radiometer (HyperOCR, HOCR) sensors in the water column. Our work focuses on the development of a robust and efficient tool for unraveling the structure and activities of natural microbial assemblages in the ocean. By applying the NMF method to HyperOCR data, we successfully extracted five spectral signatures, representing unique patterns in the data. These signatures were instrumental in predicting the abundances of various microbial components, including bacteria, heterotrophic nanoflagellates, and picoeukaryotes, showcasing the potential of ML and AI in advancing oceanographic studies. To validate these methods, the study area included a shallow coastal area under the influence of freshwater inflow and an open offshore area with a depth of 100 m. The study sites in coastal and offshore waters (Kaštela Bay and Stončica Vis, respectively) had significantly different hydrographic and microbiological characteristics. Kaštela Bay had lower temperatures and salinity than the site on Vis. We have demonstrated prediction of the structure of the microbial community through application of different AI and ML methods with specific HOCR sensors.

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Section: Discussionsupporting

confidence: 83%

Extracted Spectral Signatures from the Water Column as a Tool for the Prediction of the Structure of a Marine Microbial Community

Puškarić,

Sokač,

Ninčević

et al. 2024

JMSE

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“…To extract characteristic wind time patterns, the growing neural gas network (GNG) method was used. GNG is a clustering method, somewhat similar to the self-organising maps algorithm [28], which has been used in the ocean sciences field on numerous occasions [6,29,30]. Both are trained through unsupervised learning.…”

Section: Synoptic Field Analysis Methodsmentioning

confidence: 99%

“…From 2008, the temperature increase accelerated and showed a linear trend of 0.013 • C/month, affecting the microbial food web [5]. Temperature changes affect vertical mixing and stratification, as well as altering the nitrogen cycle and food web in the ocean [6]. The superposition of multi-decadal thermohaline fluctuations, low river discharge, dry weather conditions, and excessive evaporation relative to precipitation caused sub-surface salinity to reach a historical maximum in 2017 [7].…”

Section: Introductionmentioning

confidence: 99%

Observation of Abrupt Changes in the Sea Surface Layer of the Adriatic Sea

Matić

Džoić

Kalinić

et al. 2022

JMSE

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We observed interannual changes in the temperature and salinity of the surface layer of the Adriatic Sea when measured during the period 2005–2020. We observed non-stationarity and a positive linear trend in the series of mixed layer depth, heat storage, and potential energy anomalies. This non-stationarity was related to the climate regime that prevailed between 2011 and 2017. We observed significant changes in the interannual variability of salinity above and below the mixed layer depth and a positive difference in the surface barrier layer. In an effort to reconstruct the cause of this phenomenon, a multi-stage investigation was conducted. The first suspected culprit was the change in wind regime over the Mediterranean and Northeast Atlantic regions in September. Using the growing neural gas algorithm, September wind fields over the past 40 years were classified into nine distinct patterns. Further analysis of the CTD data indicated an increase in heat storage, a physical property of the Adriatic Sea known to be strongly influenced by the inflow of warm water masses controlled by the bimodal oscillating system (BiOS). The observed increase in salinity confirmed the assumption that BiOS activity affects heat storage. Unexpectedly, this analysis showed that an inverse vertical salinity profile was present during the summer months of 2015, 2017, and 2020, which can only be explained by salinity changes being a dominant factor. In addition, the aforementioned wind regime caused an increase in energy loss through latent energy dissipation, contributing to an even larger increase in salinity. While changes in the depth of the mixed layer in the Adriatic are usually due to temperature changes, this phenomenon was primarily caused by abrupt changes in salinity due to a combination of BiOS and local factors. This is the first record of such an event.

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“…Concerning trace elements (i.e., Hg, Cd, Pb, As, Ni), it is essential to underline that the Mediterranean Sea is a semi-closed basin and that it is surrounded by some of the most heavily populated and industrialized countries in the world [20]. For this reason, it is particularly subjected to pollution events.…”

Section: Activities Carried Outmentioning

confidence: 99%

The Interreg Project AdSWiM: Managed Use of Treated Wastewater for the Quality of the Adriatic Sea

Susmel

Girolametti²,

Fonti³

et al. 2022

Water

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The Italy-Croatia Cross Border Cooperation (CBC) Programme is the financial instrument supporting the cooperation between the two European Member States overlooking the Adriatic Sea. The first call for proposals was launched in 2017, identifying four priority axes of intervention. Subsequently, in 2019, the kick-off of the AdSWiM project “Managed use of treated urban wastewater for the quality of the Adriatic Sea” took place in Udine (IT). Adriatic marine waters are generally classified as good to excellent based on the Bathing Water Directive (2006/7/EC). Nevertheless, issues of low productivity or the lack of nutrients have been often suggested, especially on the Italian side. The project addresses the question of whether wastewater treatment plants (WWTPs) discharging to the sea, after applying appropriate pollution control and management technologies, can modulate the nutrient content of their effluents to support localized depleted areas. This idea is borrowed from one of the motivations that support the reuse of treated wastewater for irrigation, thus leading to the return of nutrients (nitrogen, phosphorus, potassium, etc.) to natural biogeochemical cycles. However, the hypothesis of modulating the nutrient composition of wastewater opens up to several critical aspects, including legislative and technological ones. Being aware of the delicate environmental implications, we have undertaken the project involving WWTPs, research centers, municipalities, and legal experts with the aim of investigating in detail the problems related to wastewater reuse, especially with regard to the content of nutrients. Our experimental approach aimed to evaluate appropriate and possibly new treatment technologies to reduce the microbial load and to implement chemical and microbiological tests on the treated wastewater. Results have shown that it can be tricky to draw decisive conclusions because (i) the wastewater management systems differ between the two sides of the Adriatic sea due to the different levels of technological development of WWTPs; (ii) the Italian and Croatian coasts deeply differ in geographic characteristics (i.e., topography, orography, current circuits, presence of rivers) and anthropogenic pressure (i.e., exploitation levels, population density); (iii) the new treatment technologies to lower bacterial contamination need further efforts to raise their technological level of readiness (TRL) and make them implementable in the existing WWTPs. However, in terms of chemical control methodologies, the proposed sensors and biosensors gave positive results, managing to decrease the detection limits for the measured parameters, and the tested technologies for microbiological monitoring were also effective. In particular, the latter was carried out by using recent molecular biology techniques, capable of resolving the microbiota in treated wastewater, which emerged to be strictly related to the features of the WWTPs.

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Impact of water column stability dynamics on the succession of plankton food web types in the offshore area of the Adriatic Sea

Cited by 14 publications

References 84 publications

Extracted Spectral Signatures from the Water Column as a Tool for the Prediction of the Structure of a Marine Microbial Community

Extracted Spectral Signatures from the Water Column as a Tool for the Prediction of the Structure of a Marine Microbial Community

Observation of Abrupt Changes in the Sea Surface Layer of the Adriatic Sea

The Interreg Project AdSWiM: Managed Use of Treated Wastewater for the Quality of the Adriatic Sea

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