Macroinvertebrate assemblages in mountain tributaries of glacial-fed and rain-fed rivers in eastern Nepal

While river macroinvertebrates are the most widely used form of bioindicators, their baseline information, although crucial, is scarce in Nepal. The main objective of this study was to assess the macroinvertebrate assemblages in mountain tributaries of the glacial-fed Tamor and rain-fed Kamala rivers. A total of eight sites were sampled during March 2015 (Spring), November 2015 (Autumn), January 2016 (Winter), and May 2016 (Summer). Altogether, 49 Families of macroinvertebrates belonging to 15 Orders were identified with 39 Families and 12 Orders in Tamor’s tributaries, and 33 Families and 10 Orders in Kamala’s tributaries. Non-metric multi-dimensional scaling (NMDS) revealed different assemblages between the two river systems. The most dominant Order in the Tamor was Ephemeroptera and it was Trichoptera in the Kamala. EPT (Ephemeroptera Plecoptera Trichoptera) assemblages were the most abundant in all four seasons for both the river systems and higher % EPT in Tamor’s tributaries indicate better water quality than in the Kamala tributaries. Typical cold water adapted Families such as Rhyacophilidae and Stenopsychidae were observed in Tamor’s tributaries whereas in Kamala’s tributaries, warm water adapted Families like Naididae and Thiaridae were found, reflecting a difference in the abiotic variables such as temperature, dissolved oxygen attributed to each of the catchments. This baseline data can serve as the foundation for further bioassessment including those of climate change impacts on aquatic biodiversity.

Relationship between anuran larvae occurrence and aquatic environment in septentrional east Palearctic landscapes

The presence of amphibian larvae is restricted by both biotic and abiotic variables of the environment. Some of these variables are still undetermined in the septentrional eastern Palearctic where Rana amurensis, Strauchbufo raddei and Dryophytes japonicus are found in large numbers. In this study, we sampled 92 sites across Mongolia, Russia and the Democratic People’s Republic of Korea and measured biotic and abiotic water variables, as well as the height of flooded terrestrial and emergent aquatic vegetation at the breeding site. We determined that the presence of anuran larvae is generally, but not always, linked to pH and temperature. Rana amurensis was not significantly affected by any of the variables measured, while S. raddei was impacted by water conductivity and D. japonicus by pH, temperature and vegetation. Our results highlight a potential risk for these species due to the changes in aquatic variables in response to desertification.

Seagrass Condition at Some Small Islands in The Taka Bonerate National Marine Park, South Sulawesi Indonesia

The assessment of seagrass bed condition in Indonesia still refers to the Decree of the State Minister for the Environment (KMNLH) no. 200 of 2004, which considers only one variable, namely the percentage of seagrass cover. To assess the seagrass beds condition to be more in-depth and meaningful, it is necessary to consider the addition of several variables, such as the biotic variables (seagrass species diversity including macroalgae and macro-benthos components) as well as the abiotic variables (reef flat areas and the substrate components). The purpose of this study is to determine the seagrass beds condition in several small islands in the Taka Bonerate National Marine Park by considering the additional analysis using both biotic and abiotic variables as mentioned above. The methodology used in this study is a combination of the use of the standard seagrass transect method, interpretation of satellite imagery related to the seagrass bottom habitat area, and its components on the reef flat of a particular island, as well as weighting and scoring based on those considered additional variables. By applying the criteria in the method, the seagrass bed conditions were then classified into three categories, namely seagrass in good, moderate, and unfavorable conditions, respectively. The results of the total score assessment on several small islands in Taka Bonerate Islands show that the seagrass bed in Latondu Besar Island is in good conditions with the highest score of (316) compared to Tarupa Besar, Jinato, Rajuni Kecil, and Tinabo Besar Islands with an average score of (173). The results of this study indicate that the assessment of seagrass conditions is more meaningful in terms of seagrass ecology than based on seagrass cover alone. However, this study requires a lot of validation for its application in assessing the condition of seagrass beds in other islands in Indonesia.

Bottom Communities and Abiotic Factors: Analysis of Statistical Relationship Using the Instability Index and Virtual Species Distribution

Statistical procedures for quantifying the relationships between the community structure and abiotic variables start with selecting a minimum set of uncorrelated environmental factors that determine the ecological conditions essential for each of the species. This is especially important when constructing models of spatial distribution of species which are key to ecology of communities and conservation of nature. The aim of the study is to explore whether some applications of information theory can be used to rank environmental factors with respect to their contribution to the formation of the ecological structure of aquatic communities. We consider the applicability of the instability index, which is a special case of the Kullback-Leibler entropy divergence and reflects the information gain from the displacement of a particular realization of a random variable relative to its mean value. Using of instability indices allows to reduce multidimensional data sets on species structure of communities and abiotic factors to lower dimension sets of commensurate standardized variables and to explore the relationships between the latter. The initial data we used were the results of the long-term (1990–2019) hydrobiological survey of benthic communities in small and medium-sized rivers in the Middle and Lower Volga regions. We consider the indices of instability calculated for each of 147 taxa of macrozoobenthos and 8 geophysical and hydrochemical indicators. Based on these data, we constructed random forest regression models and calculated potential weights of environmental factors that determine ecological preferences of species. The most significant explanatory variables were used to construct distribution maps of «virtual species», which were compared with the corresponding empirical data. A habitat suitability map of chironomids (Diptera, Chironomidae), the Prodiamesinae subfamily, is presented. Instability indices can be effectively used for exploratory analysis of various ecosystems, e. g. ranking habitats according to the degree of environmental instability and / or species associations, selecting the most informative abiotic variables that determine the population density of the taxa, etc.

Cathemeral activity by sloths (Bradypus variegatus, Bradypodidae) in Amazonian black-water floodplain forest (igapó)

Both biotic and abiotic factors are important for maintaining the activity cycles of animals, and may determine the most advantageous periods for eating, moving and sleeping. While the solar day-night cycle is among the most central of abiotic variables, a number of species are active both day and night. Three-toed sloth populations (Bradypus, Linnaeus 1758) across the Neotropics show this pattern, with activity occurring at various points across the 24-hour cycle. In the current study, we used radio tracking techniques to investigate the daily temporal patterning of sloth displacement in Amazonian igapó flooded forest, and compared the results with populations studied in other habitats. We conclude that igapó sloths are cathemeral, and discussed that environmental temperature, nutritional needs and the presence of predators may be the main factors influencing their activity pattern.

Impact of environmental changes on the behavioral diversity of the Odonata (Insecta) in the Amazon

The odonates are insects that have a wide range of reproductive, ritualized territorial, and aggressive behaviors. Changes in behavior are the first response of most odonate species to environmental alterations. In this context, the primary objective of the present study was to assess the effects of environmental alterations resulting from shifts in land use on different aspects of the behavioral diversity of adult odonates. Fieldwork was conducted at 92 low-order streams in two different regions of the Brazilian Amazon. To address our main objective, we measured 29 abiotic variables at each stream, together with five morphological and five behavioral traits of the resident odonates. The results indicate a loss of behaviors at sites impacted by anthropogenic changes, as well as variation in some morphological/behavioral traits under specific environmental conditions. We highlight the importance of considering behavioral traits in the development of conservation strategies, given that species with a unique behavioral repertoire may suffer specific types of extinction pressure.

Abiotic Environment Predicts Micro- but Not Macroevolutionary Patterns of Flower Color in Monkeyflowers (Phrymaceae)

Anthocyanin pigments are responsible for many of the vivid pink, purple, red, and blue flower colors across angiosperms and frequently vary within and between closely related species. While anthocyanins are well known to influence pollinator attraction, they are also associated with tolerance to abiotic stressors such as extreme temperatures, reduced precipitation, and ultraviolet radiation. Using a comparative approach, we tested whether abiotic variables predict floral anthocyanin in monkeyflowers (Phrymaceae) across western North America. Within two polymorphic species, we found that abiotic variables predicted flower color across their geographic ranges. In Erythranthe discolor, the frequency of pink flowered (anthocyanin producing) individuals was greater in populations with reduced precipitation. In Diplacus mephiticus, the frequency of pink flowered individuals was greater at higher elevations that had reduced precipitation and lower temperatures but less ultraviolet radiation. At the macroevolutionary scale, across two parallel radiations of North American monkeyflowers, species with floral anthocyanins (pink, purple, or red corollas) occupied areas with reduced precipitation in Erythranthe but not Diplacus. However, after accounting for phylogenetic relatedness, we found no evidence for the joint evolution of flower color and environmental affinity in either clade. We conclude that although abiotic stressors may play a role in the evolution of flower color within polymorphic species, we found no evidence that these processes lead to macroevolutionary patterns across monkeyflowers.