Search

Mountain lakes are unique and often isolated freshwater habitats that harbour a rich biotic diversity. This high conservation value may be reflected by diatoms, a group of algae that is known for its reliability as a bioindicator, but which has not been studied extensively in mountain lakes of the northern European Alps. In this study, the conservation value of these lakes was assessed by characterizing the number, share, and abundance of diatom Red List (RL) taxa and their relationship with environmental variables, diatom α and β diversity (assemblage uniqueness). For this purpose, linear regression models, generalized linear models, and generalized additive models were fitted and spatial descriptors were included when relevant. Of the 560 diatom taxa identified, 64% were on the RL and half of these were assigned a threat status. As hypothesized, a decreasing share of RL species in sediment and littoral samples at higher trophic levels was reflected by higher total phosphorous content and lower Secchi depth, respectively. Species-rich lakes contained a high number of RL taxa, contrasting our hypothesis of a logarithmic relationship. In turn, RL abundance increased with uniqueness, confirming our initial hypothesis. However, some of the most unique sites were degraded by fish stocking and contained low abundances of RL species. The results demonstrate the importance of oligotrophic mountain lakes as habitats for rare freshwater biota and their vulnerability in light of human impact through cattle herding, tourism, damming, and fish stocking. Additional conservation efforts are urgently needed for mountain lakes that are still underrepresented within legal conservation frameworks. Species richness and uniqueness reflect complementary aspects of RL status and thus should be applied jointly. Uniqueness can indicate both pristine and degraded habitats, so that including information on human impacts facilitates its interpretation. [ABSTRACT FROM AUTHOR]

In this Special Issue only studies focused on macroalgae from marine rocky shores were presented, while studies about macroalgal biodiversity in freshwater habitats and marine soft bottoms and plankton were not submitted. Additionally, living macroalgae form sea forests or macroalgal beds that provide habitat and refuge for many other organisms, thereby enhancing local biodiversity [[4]]. Macroalgae are a diverse and pervasive element of rocky shores [[1]] but a few species can also be found on soft bottoms or living in the water column. [Extracted from the article]

Simple Summary: Increased public awareness of wetlands and the importance of their conservation stipulated various preservation or improvement projects. In 2012, riverine wetlands were created in the Nakdong River in Korea to replace those damaged or destroyed by the River Refurbishment Project, but they could not be maintained as functional wetlands, owing to the long-term neglect and lack of management. A previous survey detected various problems in these wetlands, including insufficient in/outflow function, shore instability, and difficulty in introducing appropriate water sources, which cause nutrient accumulation and algal blooms. The in/outflow functions of the mainstream and tributaries were hampered by soil and plant deposition. These chemical changes influenced the community composition of rotifers. In particular, three rotifer species—Brachionus, Keratella, and Trichocerca—were mainly distributed in wetlands with relatively high nutrient concentrations (total nitrogen and phosphorus). Therefore, the rotifer community can be used as an indicator of the nutritional status of a wetland, and the functional state of the wetland can be understood through continuous monitoring of rotifers. Hydrological characteristics of freshwater ecosystems are powerful determinants of the distribution of biological communities and changes in environmental factors. This study identified relationships between the wetland environment, rotifer community, and hydrological factors for 48 wetlands, to determine their impact on wetland conservation and management. Different hydrological factors produced different wetland environments, which influenced the rotifer community composition. The wetlands with "poor" "in/outflow function" and "shore stability" levels showed high conductivity, turbidity, depth, and concentrations of total nitrogen, total phosphorus, and chlorophyll a. In contrast, the dissolved oxygen levels and velocity were the highest in wetlands with "good" in/outflow function and shore stability variables. The nutritional status of each wetland affected the composition of the rotifer community. Some genera (Keratella, Brachionus, Anuraeopsis, Trichocerca, and Philodina) were found in wetlands with high concentrations of total nitrogen, total phosphorus, and chlorophyll a, and high turbidity and depth. In contrast, Ascomorpha and Ploesoma were found in wetlands with high dissolved oxygen levels and flow velocity. High densities of Lepadella, Lecane, and Testudinella were found in wetlands completely covered by macrophytes. The rotifer community distribution can be used to understand the trophic, current functional, and environmental status of wetlands. [ABSTRACT FROM AUTHOR]