Analiza kvaliteta vode pritoka Vrutci akumulacije pomoću diatomnih indeksa

Silikatne alge su važna grupa akvatičnih organizama osetljivih na promene u svojoj životnoj sredini. Međutim, njihova praktična upotreba kao bioindikatora je relativno nova u Srbiji. U ovom istraživanju sakupljeni su epilitski uzorci iz 14 pritoka akumulacije Vrutci u toku septembra i oktobra 2014. godine. Identifikovano je ukupno 84 taksona silikatnih algi. Najveće populacije u okviru epilitske zajednice silikatnih algi u većini pritoka grade Cocconeis placentula var. lineata i Achnanthidium minutissimum var. minutissimum. Rezultati izračunavanja dijatomnih indeksa, uz pomoć softverskog paketa OMNIDIA, ukazuju da je ekološki status vode većine ispitivanih pritoka odličan do dobar. Samo rezultati dijatomnih indeksa za pritoke Simića potok, Konjski potok, Bioštanska Banja i neimenovanu pritoku 13 pokazuju prisustvo umerene antropogene eutrofikacije

First Report on a 5-Year Monitoring of Lampenflora in a Famous Show Cave in Serbia

Many show caves are vulnerable to various disturbances, meaning that conservation of such habitats, which would include monitoring of their ecological parameters and lampenfora (a growing problem worldwide), should be a priority. For the frst time in Serbia, lampenfora was monitored continously for 5 years (2016–2020), three times per year during the tourist season, in the Lazar Cave. Artifcial light created favorable conditions for the proliferation of phototrophic microorganisms that were developed not only as epiliths, but also endoliths, which poses a greater danger for cave substratum and structures. Although a higher diversity in general was found in Cyanobacteria (coccoid forms mostly), Chlorophyta were more widespread and abundant in samples, among which Chlorella, Stichococcus bacillaris, and Klebsormidium faccidum stood out. Chlorella is one of the genera making lampenfora dangerous, as it can switch from an autotrophic to a mixotrophic, and fnally to a heterotrophic lifestyle. The mosses protonema and mosses itself were also present. Even though the cave is closed for 6 months every year, lampenfora “legacy” always persisted on all sites from the previous year, spreading further over the years. Measured parameters (temperature, relative air humidity, light intensity, substrate pH, and substratum moisture), primary production, and bioflm parameters showed yearly, seasonal, or sampling site variations. Statistical analyses were used to examine the efect of the sampling year, the season, and sampling site on the selected measured parameters, while multivariate analyses were performed with taxa in relation to year, season, site, and main ecological parameters

Procena trofičkog statusa akumulacije očaga (Lazarevac, Srbija) posredstvom Carlsonovog indeksa

Trofički status se može definisati kao ukupna težina živog biološkog materijala (biomase) u nekom vodenom telu na određenom lokalitetu i u određeno vreme. Trofički status nekog vodenog tela može se proceniti na osnovu merenja specifičnih parametara i predstavlja biološki odgovor na spoljašnje faktore, kao što su količina nutrijenata, sezonske promene, ispaša, mešanje vode itd. Procena trofičkog statusa jezera ili akumulacije je od velikog značaja. Postoje različiti kriterijumi za procenu trofičkog stanja jezera, kao što su: koncentracija nutrijenata, produktivnost, kvantitativni i kvalitativni sastav flore i faune, dostupnost kiseonika i morfometrija jezera. Međutim, imajući u vidu da je multiparametarski indeks nepraktičan, Carlson je predložio indekse trofičkog stanja (TSIs) koji su znatno jednostavniji za upotrebu od multiparametarskog indeksa. Ovi indeksi kao bazu za klasifikaciju trofičkih stanja koriste algalnu biomasu. U tom smislu koriste se tri parametra za izračunavanje ovih indeksa: koncentracija hlorofila a, ukupni fosfor i providnost izmerena Secchi diskom. Svaka od ove tri promenljive se može koristiti za klasifikaciju statusa vodenog tela, ali je hlorofila a najznačajniji parametar s obzirom da je direktni pokazatelj algalne biomase. Opseg Carlson-ovog trofičnog indeksa obuhvata vrednosti od 0 do 100. Vrednosti ispod 40 odgovaraju oligotrofnim, od 40 do 50 mezotrofnim, od 50 do 70 eutrofnim, a preko 70 hipereutrofnim jezerima i akumulacijama. Glavna prednost ovog indeksa je što odnos između tri parametra može ukazati na određene uslove koji vladaju u datom jezeru ili akumulaciji, a tiču se faktora koji limitiraju algalnu biomasu ili utiču na izmerene parametre. Iako određivanje trofičkog statusa vode nekog vodenog tela ne treba poistovećivati sa samim kvalitetom vode, ono, svakako, predstavlja značajan aspekt istog. Cilj ovog istraživanja bio je određivanje trofičkog statusa jezera Očaga na osnovu Carlson-ovog trofičnog indeksa i ispitivanje veze između izračunatih indeksa za hlorofil a (TSI(CHL)), ukupni fosfor (TSI(TP)) i providnost merenu Secchi diskom (TSI(SD)). Veštačko jezero Očaga nalazi se u blizini Lazarevca i isključivo se koristi za rekreaciju. Ispitivanje vode rađeno je jednom nedeljno tokom jula i avgusta, od 2012. do 2014. godine. Sve analize urađene su u Zavodu za javno zdravlje iz Beograda. Vrednosti dobijenih indeksa (TSIs) varirale su od 41 do 86.25, u ispitanom periodu, a jezero je menjalo status od mezotrofnog, preko eutrofnog do hipereutrofnog, pri čemu su eutrofni uslovi preovladavali. Hipereutrofija je zabeležena tokom avgusta 2013. Godine, kada su bile izmerene i najveće vrednosti sva tri parametra, što je, verovatno, rezultat organskog opterećenja vodenog ekosistema i vremenskih uslova. Prema podacima RHMZ-a, 2013. godina je bila jedna od najtoplijih i najsušnijih godina još od 1951. godine. Nasuprot tome, u avgustu 2014. godine izmerene su najmanje vrednosti svih parametara, što ukazuje na mezotrofne uslove u jezeru te godine. Mezotrofni status jezera je, verovatno, posledica velike količine padavina u prvoj polovini te godine, ali i pražnjenja i ponovnog punjenja jezera nakon majskih poplava

Phytoplankton response to the mass removal of black bullhead in the Ponjavica River

Allochthonous and invasive species are among the main factors leading to biodiversity loss which further threatens the ecosystem functioning, stability and resilience. A modern way of life and climate changes accelerated and increased the spread of invasive species. Although many ecosystems are facing this problem, the most endangered ones are slow-flowing/stagnant shallow waters. The black bullhead (Ameiurus melas) is recognized as one of the most successful non-native fish species in European freshwaters. Regarding its mitigation, selective mass removal is considered as an effective method to reduce the abundance of the local population. This biomanipulative measure undoubtedly affects other ecosystem components, so monitoring of organisms from different trophic levels is crucial for assessing the impact and success of the whole process. The aim of this study was to detect and examine the changes in phytoplankton structure and abundance, as a response to the mass removal of the black bullhead. Selective removal took place in the lowland Ponjavica River in the same-named Nature Park in Serbia with the domination of black bullhead and urgent need for biodiversity recovery. The removal project was conducted from June to October 2018 and April to October 2019. The removal process was conducted at three localities along the protected part of the Ponjavica River. Along with fish removal, phytoplankton samples for qualitative and quantitative analyses were collected by plankton net and Van Dorn bottle, respectively. The taxonomic literature was used for qualitative analysis, while the Utermöhl method was conducted for the assessment of phytoplankton abundance. More than 200 algal taxa were detected in Ponjavica phytoplankton. Phytoplankton abundance at each of the localities showed similar dynamics ranged from minimal 156914 cell/ml in June, to maximal 1038946 cell/ml in August 2018. Cyanobacteria were the dominant group with more than 98% in total cell number from August to October. Three invasive and potentially toxic cyanobacteria (Raphidiopsis raciborskii, Sphaerospermopsis aphanizomenoides, Raphidiopsis mediterranea) were registered with 61% in total cell number in August, 59% in September and 38% in October 2018. Phytoplankton abundance decreased (by almost half) in the second year of the project, together with the share of invasive and potentially toxic cyanobacteria in the total cell number and particularly a number of individuals. The black bullhead and Raphidiopsis raciborskii are considered as the most successful invasive species among fish and cyanobacteria, respectively, and both are detected in the Ponjavica River. Our results showed that mass removal of black bullhead caused a decrease in phytoplankton abundance and also portion of present invasive cyanobacteria without newly occurred ones, while in the case of ichthyofauna other species increased the population abundance due to free niche. Great efforts are being made to find adequate solutions for invasive species removal but a unique and successful method has not been found so far. The selective mass removal is the best method to decrease the black bullhead abundance and the results of this research indicated that the process could have a positive effect on decreasing the abundance of invasive species at the base of the trophic chain

Endolithic phototrophs: Examples from cave-like environments

Endoliths are more frequently found in extremely harsh environments, but they can inhabit mesic climate and subterranean habitats as well. Whether they are adapted to life inside rocks or do they seek refuge in this way, remains largely unknown for caves and pits. Consequently, subterranean habitats in limestone areas, were explored: three caves in Serbia (Cerjanska, Petnička and Potpeć) and one pit in Croatia (Keranova Golubinka). Sampling of rock substratum containing endoliths was performed at various distances from the entrance, at sites characterized by a lower level of light intensity. Phototrophs were separated from the rock matrix using 10% hydrochloric acid and analyzed using light microscopy. In general, low diversity of endoliths was observed, but representatives from Cyanobacteria, Chlorophyta and Xanthophyta were found. Cyanobacteria, more precisely coccoid forms (genera Aphanocapsa, Chroococcidiopsis, Gloeocapsa, Gloeocapsopsis, Synechococcus), were dominant. The most interesting cyanobacterial taxon, Leptolyngbya-like taxon, representing a true endolith (euendolith), was found in the Petnička Cave. This taxon and its relation to the substratum, as well as chasmoendolithic community from the Keranova Golubinka Pit, were observed using Scanning electron microscopy (SEM). It was observed that chasmoendoliths inhabit already existing surface rock cracks and fissures, while a true endolith actively bores into the substratum. Non-metric multidimensional scaling (NMDS) was performed to observe the similarity between the sampling sites. Endoliths can grow inside the rocks, making them very successful biodeteriogens, which is not a desirable trait for caves and pits that are characterized by various attractive geomorphological features that need to be preserved. Thus, considering these habitats, more attention should be paid to the endolith community in the future

List of phytoplankton, zooplankton and zoobenthos species abundances

We studied the effects of changed quality of inflow water of aquaculture ponds on three aquatic communities, phytoplankton, zooplankton and zoobenthos, during two seasons of rearing common carp (Cyprinus carpio). The new water source coming from a deep tube well was markedly different in water chemistry from the surface water sources previously used to maintain the investigated fish ponds. Ponds supplied by the tube well water were characterized by lower oxygen and water hardness, and higher total ammonia and conductivity reaching subsaline conditions. Multivariate analysis (co-inertia) revealed that all investigated groups, except Mollusca (zoobenthos), decreased in species richness, abundance and biomass due to changed water chemistry, but differed in the level of susceptibility to stressors. Assemblages of Rotifera and Cladocera were the most affected showing a sharp decline in density and number of species since 29 out of 44 species disappeared from the ponds. The abundance of Copepoda (Cyclopoida) was relatively high although significantly lower in new environmental conditions (P<0.05), with adults being more tolerant to changed inflow water than larvae. Phytoplankton, except Bacillariophyta, had a highest potential to replace previous species with newcomers more adapted to changed inflow water, providing 36 immigrant species while 49 became extinct. Although mainly influenced by fish predation, Chironomidae (zoobenthos) were undoubtedly affected by changed water chemistry, decreasing from 11 to only 3 species. These results suggest that this pattern was a result of the shift from freshwater to subsaline conditions

An updated list of Serbian diatom flora: New recorded taxa

Diatoms are a widespread group of organisms with well-known ecological preferences. Knowledge of their diversity is of great importance for assessing the environmental status of different aquatic ecosystems. The present study was based on 55 different localities that included rivers, streams, channels, accumulations and salt marshes throughout Serbia. The results of this study expanded the diatom checklist by 80 taxa, including two new recorded genera (Fistulifera and Microfissurata) for Serbia. The data were obtained by combining light microscopy (LM) and scanning electron microscopy (SEM) that provided reliable identification, which is very important in diatom diversity studies