RED LIST OF BULGARIAN ALGAE. II. MICROALGAE.

The Red List presented in this paper is focused on Bulgarian non-marine microalgae which face a risk of extinction. The assignment to each IUCN Red List category is according to the seven specific criteria and their relative values in the new method for an evaluation of the threatened status of microalgae (STOYNEVA-GÄRTNER ET AL., this volume). The list contains 756 taxa (613 species, 82 varieties and 61 forms) from 7 divisions, classified in six IUCN categories and shows that threatened microalgae represent 14% the total algal biodiversity of Bulgaria

REVIEW OF THE CURRENT STATUS AND FUTURE PERSPECTIVES ON PSEUDOGYMNOASCUS DESTRUCTANS STUDIES WITH REFERENCE TO SPECIES FINDINGS IN BULGARIA

Emerging infectious diseases are a well-known threat to the wildlife and require complex research. There is a rapidly accumulating knowledge on the infectious disease of bats, named firstly White Nose Syndrome (WNS) and afterwards – White Nose Disease (WND), and its causative agent – the pathogenic fungus Pseudogymnoascus destructans. Although mass mortality of bats, known since a decade, is currently restricted to North America, the pathogen is of global concern as a potential threat to other hibernating bat populations. Therefore five years after the first comprehensive synthesis on the fungal ecology and relevant knowledge gaps (FOLEY ET AL. 2011), we decided to summarize the published information on the pathogen morphology, reproduction, ecological requirements, geographic distribution and systematic position. In addition, the present review compiles the available data on the affected bat species, mechanisms of WND, on the host response and on the effective treatment strategies with possible methods for fighting the pathogen to reduce the mortality in affected regions as well. Special attention is paid to the finding of the fungus in Bulgarian caves

Long‐term change of phytoplankton in Lake Kivu: The rise of the greens

Phytoplankton time‐series enable the observation of recurrent seasonal patterns on community composition, but drastic shifts in community structure are rarely observed, unless linked to anthropogenic impacts (e.g. changes in nutrient inputs). Here, we report a unique case of non‐seasonal, multiannual regime shift of phytoplankton community structure in Lake Kivu, East Africa, and explore the possible causes for such changes. 2. We recorded phytoplankton biomass every 2 weeks over a period of 12 years (from 2002 to 2015). Phytoplankton community previously dominated by cyanobacteria and diatoms changed considerably from 2012, with a conspicuous rise in the biomass of green algae (from 3 to 33% lake‐wide), and a decline of cryptophytes and cyanobacteria along with an increase in total chlorophyll a concentration. Concomitantly, we observed significant differences in the mixed layer depth between the two periods, resulting from changes in the thermal gradient. The euphotic zone depth was also reduced in 2012–2015, probably from the higher phytoplankton biomass. Moreover, mean particulate nitrogen and phosphorus increased as well as the particulate N:P ratio. 3. Desmids (Cosmarium laeve) now dominate the mixolimnion, probably due to atelomixis, observed in high‐frequency temperature measurements. We believe that decadal or multidecadal variability of climate on the Indian Ocean may be the reason for this regime shift in thermal stratification, with a strong impact in phytoplankton community structure. 4. In conclusion, our study demonstrates that tropical lakes may be subject to nonseasonal fluctuations that generate multiannual regime shifts. These regime shifts have probably never been reported previously because of the lack of long phytoplankton time‐series in low latitudes.Peer reviewe

Cyanoprokatyote and algal biodiversity in the tropical lake Edward (Africa) with notes on new, rare and potentially harmful species

The paper presents data on the biodiversity of prokaryotic and eukaryotic algae in the tropical Lake Edward, compiled from publications of the Damas mission (1935-1936), Hecky & Kling (1987) and our own results from a recent investigation of the lake phytoplankton in a three-year period (2016-2018) in the frame of the HIPE (Human impacts on ecosystem health and resources of Lake Edward) project (http://www.co2.ulg.ac.be/hipe). The provided checklist is based on modern algal taxonomy with relevant synonymizing of lists of previous authors. In total, 577 taxa from seven divisions were registered in the lake waters and in the Kazinga Channel. The richest division was Ochrophyta (287 taxa, 274 of which from Bacillariophyceae), followed by Chlorophyta (131 taxa), Cyanoprokaryota (134), Streptophyta (14), Euglenophyta (8), Pyrrhophyta (5) and Cryptophyta (1). 52 species (or only 1% of the taxa found) persisted in the lake since 30s of the 20th century till nowadays. More than half of the cyanoprokaryotes (65) are potentially toxic and harmful species. The checklist contains also data on algal abundance and frequency of occurrence, originally provided by the authors. In the phytoplankton samples, collected during the three cruises of the HIPE project, 248 taxa were found, among which the richest division was Cyanoprokaryota (104). From this total of 248 taxa, only 3 were frequent and 199 were very rare (from 1-3 samples) with 121 taxa found in one sample only. During 2016-2018, the most abundant species in the lake phytoplankton belonged to Cyanoprokaryota, Bacillariophyceae and Chlorophyta. The algae found in the lake have different ecological requirements and besides clear tropical species and some cosmopolites, some “cold water species” from northern and temperate regions were found. For them, as well as for some thermophilic species, considered alien for the lake, transport through different vectors was supposed. In the literature analyzed, 36 new taxa were described. Among them 26 taxa had Lake Edward as a single locality, and 10 were found also in other lakes and adjacent water bodies. Twelve of these new taxa were checked by modern taxonomists, but 24 still need taxonomic reconsideration.HIP

CONTENTS 1. А NEW METHOD FOR ASSESSMENT OF THE RED LIST THREAT STATUS OF MICROALGAE

Although the IUCN Red List Categories and Criteria is a widely internationally used system for classifying species at high risk of extinction, the micro-organisms are still practically excluded from the appropriately enlisted taxa. The present paper provides a method, which gives means to assess microalgae threat status much more objectively than it was possible before and in this way to achieve quite high degree of generalization in work with this peculiar group of organisms. The method described below uses the widely accepted standard IUCN Red List system of categories, but proposes their assignment on the basis of a complex application of seven criteria relevant to microalgae and classical data, available for them. These criteria can be interpreted in the same way for all taxonomic groups of algae and for all possible territorial levels (local, national, regional, global). The criteria are denominated with Latin capital letters A-G and each of them has a numerical expression with values (points) ranging between 4 and 1. The final assessment of the threat status is done on the basis of the total amount of points (T), which ranges between 7 and 28. In this way each alga is supplied with a formula (a combination of letters and numbers), which indicates its threat status and in the same time outlines its most critical, “weak spots” on which special attention has to be paid when conservation measures have to be proposed. As it is exemplified in detail in the paper, the formula could be expressed in a table or in a text format, in full or in a short version, depending on the needs of the relevant studies or proposals (e.g. Anabaena lapponica Borge [VU - A3 B4 C4 D2 E2 F2 G3], or Anabaena lapponica Borge [VU - A3 B4 C4 D2 E2 F2 G3 T20], or Anabaena lapponica Borge [VU - T20]), or Anabaena lapponica Borge [VU])

Diversity of the Summer Phytoplankton of 43 Waterbodies in Bulgaria and Its Potential for Water Quality Assessment

The general awareness of the threats on biodiversity and water quality raised the number of studies that use phytoplankton in assessment procedures. Since most metrics require obtaining mean values, this paper presents data that may help speed up field work and find indicators for a rapid water quality assessment based on single samplings, allowing simultaneous work on many sites. The phytoplankton from 43 Bulgarian waterbodies collected during three summer campaigns (2018, 2019, 2021) at sites selected after drone observations was studied by conventional light microscopy (LM) and an HPLC analysis of marker pigments. Our results allowed us to recommend drones and the HPLC application as reliable methods in rapid water quality assessments. In total, 787 algae from seven phyla (53 alien, new for Bulgaria) were identified. Chlorophyta was the taxonomically richest group, but Cyanoprokaryota dominated the biomass in most sites. New PCR data obtained on anatoxin and microcystin producers confirmed the genetic diversity of Cuspidothrix and Microcystis and provided three new species for the country’s toxic species, first identified by LM. A statistical analysis revealed significant correlations of certain algal phyla and classes with different environmental variables, and their species are considered promising for future search of bioindicators. This is especially valid for the class Eustigmatophyceae, which, as of yet, has been almost neglected in water assessment procedures and indices