Bacterial Microbiomes in the Sediments of Lotic Systems Ecologic Drivers and Role: A Case Study from the Mureş River, Transylvania, Romania

Numerous sections of the Mureş River vary in terms of the abundance of nitrates, ammonia, and orthophosphates; and of correlated lotic sediment bacterial microbiome structures in terms of both diversity and abundance. This highlights the great versatility of microbiomes in being influenced by the physical-chemical characteristics of environments and their spatial changes. Bacteria microbiomes exhibit dynamic and shifting potential and significant tendencies toward self-organization and self-adaptation. These typical features represent an essential ecologic basis for lotic systems having to do with the use and reuse of various kinds of environmental resource as chemical substances. In this respect, trophic processes assure the river ecosystem optimum health ecologic status dynamic and trend, to be reached. The flexibility of shifting bacterial microbiomes is crucial in maintaining this ecological context’s vital role in biogeochemically sustaining other taxonomic groups, which are spatially and temporally continuous. This is especially important for nutrient cycle processes, even for rivers with high levels of negative human impact, in promoting a functional lotic system.

The Role of Aquatic Refuge Habitats for Fish, and Threats in the Context of Climate Change and Human Impact, during Seasonal Hydrological Drought in the Saxon Villages Area (Transylvania, Romania)

In spite of the obvious climate changes effects on the Carpathian Basin hydrographic nets fish fauna, studies on their potential refuge habitats in drought periods are scarce. Multiannual (2016–2021) research of fish in some streams located in the Saxon Villages area during hydrological drought periods identified, mapped, and revealed the refuge aquatic habitats presence, management needs, and importance for fish diversity and abundance for small rivers. The impact of increasing global temperature and other human activities induced hydrologic net and habitats alteration, decreased the refuge habitats needed by freshwater fish, diminished the fish abundance, and influenced the spatial and temporal variation in fish assemblage structure in the studied area. The sites more than one meter in depth in the studied lotic system were inventoried and all 500 m of these lotic systems were also checked to see what species and how many individuals were present, and if there is was difference in their abundance between refuge and non-refuge 500 m sectors. The scarce number of these refuges due to relatively high soil erosion and clogging in those basins and the cumulative effects of other human types of impact induced a high degree of pressure on the fish fauna. Overall, it reduced the role of these lotic systems as a refuge and for reproduction for the fish of downstream Târnava Mare River, into which all of them flow. Management elements were proposed to maintain and improve these refuges’ ecological support capacity.

Diversity and distribution of odonates in Rani Reserve Forest, Assam, India

Odonata are the bioindicators of freshwater ecosystem health and is recognised as an excellent ‘flagship’ group among insects. Baseline knowledge on the diversity and distribution of odonates over spatiotemporal scale is the key to biodiversity conservation. Rani Reserve Forest of Assam is a mosaic of all the habitat types suitable for odonates. The present work aims at studying the diversity and distribution of Odonates in Rani Reserve Forest. The study was carried out from December 2014 to November 2017 by categorising the study area into three major habitat types: 1. lentic system, 2. lotic system and 3. terrestrial woodland. A total of 67 species belonging to 44 genera, representing 11 families were recorded. First published records of three species, Onychothemis testacea (Libellulidae), Philoganga montana (Philogangidae) and Indocnemis orang (Platycnemididae) from the state are also provided herewith. Species richness was the highest in lentic system whereas recorded the lowest in running waters of larger forested streams. Shannon diversity index also indicated that the lentic system is relatively diverse (2.95) and smaller streams of the lotic system showed the highest species evenness (0.87). Libellulidae (43%) was found to be the most dominant family belonging to suborder Anisoptera followed by Coenagrionidae (22%) of suborder Zygoptera. Philogangidae (1%) recorded the lowest number of species. Taxonomically related species showed distinct ecological segregation within these different habitat types occupying different microhabitats therein.

The Establishment and Rapid Spread of Sagittaria Platyphylla in South Africa

Sagittaria platyphylla Engelm. (Alismataceae) is a freshwater aquatic macrophyte that has become an important invasive weed in freshwater systems in South Africa, New Zealand, Australia, and recently China. In South Africa, due to its rapid increase in distribution and ineffective control options, it is recognised as one of the country’s worst invasive aquatic alien plants. In this paper, we investigate the spread of the plant since its first detection in 2008, and the management strategies currently carried out against it. Despite early detection and rapid response programmes, which included chemical and mechanical control measures, the plant was able to spread both within and between sites, increasing from just one site in 2008 to 72 by 2019. Once introduced into a lotic system, the plant was able to spread rapidly, in some cases up to 120 km within 6 years, with an average of 10 km per year. The plant was successfully extirpated at some sites, however, due to the failure of chemical and mechanical control, biological control is currently being considered as a potential control option.

Innovative On-Site Adapted System for Fish Migration with Flow Divider and Glass Collector Basin

The authors designed a new site-adapted fish passage system for upstream and downstream migration of small and large fish on the urban sector of the Bistriţa River. The longitudinal connectivity of this lotic system is interrupted by numerous transversal hydrotechnical works (weirs). This proposed system was designed to facilitate fish migration, promote fish recolonization of upstream and downstream habitats, allow the expansion of fish range, and increase spawning potential. All components of the proposed system are attached to a concrete girder located to the right stream bank, except a glass basin that is submerged in the riverbed. The positioning of the system in this girder ensures its resistance to high water events, while offering safe passage for fish in both directions.

A new species of Cymbella (Bacillariophyceae, Cymbellaceae) from the Pavana River, Western Ghats, India

New diatom species from the genus Cymbella is described, Cymbella pavanaensis from the Pavana River situated in Pimpri-Chinchwad, Pune, Maharashtra, India. The new species description is based on detailed LM and SEM morphological observations. Comparison of the new species with similar, previously-described taxa is made. C. pavanaensis belongs to a group of small-celled species of the genus, which lack differentiated, rounded porelli comprising the apical pore fields. This taxon is reported from a moderately to the highly-polluted urban lotic system, which signifies that even the diatom flora of easily accessible habitats of India is yet to be fully documented.

Field validation of an eDNA assay for the endangered white-clawed crayfish Austropotamobius pallipes

The white-clawed crayfish Austropotamobius pallipes has undergone extensive declines within its native range in the last century. Because of its threatened status, European legislation requires the species to be regularly monitored and that Special Areas of Conservation (SACs) be designated for it. Knowledge on the distribution of this species is vital for addressing these needs. This study presents an environmental (e)DNA assay to detect A. pallipes in water samples, based on the mitochondrial cytochrome oxidase I (COI) gene, utilizing species-specific primers, a minor groove binding (MGB) probe and quantitative PCR. The results of this study indicate that eDNA is an effective tool for detecting A. pallipes in a lotic system, and could provide a valuable, non-invasive method for determining the distribution of this species.