Developing a System Dynamics Model for the Nizhniy Kaban and Sredniy Kaban Lakes, Kazan, Russia, Assessing the Impacts of Phosphorus and Nitrogen Inputs on Lake Ecology

The Kaban Lakes Integrated Assessment Model (KLIAM) was developed for the lake hydrology, chemistry, and plankton dynamics of the Nizhniy Kaban and Sredniy Kaban lakes, Kazan, Russia. KLIAM is able to describe the variations seen in the Kaban lakes chemical and biological states as far seen through measurements available at the moment. KLIAM is able to reconstruct the lake history as it is approximately known from the data and written narratives. KLIAM was used to assess the measures to return the lakes to their original pre-urban status as alkaline and semi-oligotrophic lakes. The Kaban Lakes periodically goes through plankton blooms, as seen in the lake in the last decades since before World War II, which are caused by plankton growth promoted by phosphorus and nitrogen coming to the lakes as pollution from the human environment. In the new plans for development of the area surrounding the Nizhniy Kaban and Sredniy Kaban lakes, we suggest that attention is paid to reducing phosphorus and nitrogen flows to the lakes, as the best way to improve their ecological status. This is based on simulations with KLIAM. We recommend that the monitoring of lake chemistry and lake ecology is improved with reoccurring analysis of samples from the Kaban Lakes.

Library-independent source tracking of fecal contamination in selected stations and tributaries of Laguna Lake, Philippines

Laguna Lake is the largest inland freshwater body in the Philippines. Although it is classified to be usable for agricultural and recreational purposes by the country's Department of Environment and Natural Resources (DENR), studies looking at lake ecology revealed severe fecal contamination which contributes to the deterioration of water quality. Determining the sources of fecal contamination is necessary for lake protection and management. This study utilized a library-independent method of microbial source tracking (LIM-MST) to identify sources of fecal contamination in selected Laguna Lake stations and tributaries. Genetic markers of the host-associated Escherichia coli, heat-labile toxin (LTIIA) and heat-stable II (STII), were used to identify cattle and swine fecal contaminations, respectively. Meanwhile, human mitochondrial DNA (mtDNA) was used to identify human fecal contamination. Results identified the presence of agricultural and human fecal contamination in Laguna Lake Stations 1 and 5, Mangangate River, and Alabang River. The selected sites are known to be surrounded by residential and industrial complexes, and most of their discharges find their way into the lake. The identification of the specific sources of fecal contamination will guide management practices that aim to regulate the discharges in order to improve the water quality of Laguna Lake.

The use of the term ‘limnology’ and its scientometrics consequences for limnologists

Jargon is the specialised vocabulary of any science: it allows the creation of new terms to define concepts and it removes ambiguity from scientific communication. Yet, it may also hinder understanding for a broader audience. Given that the Journal of Limnology has jargon in its title, we here investigate the impact of the term ‘limnology’ on the way limnologists work, publish their research, and attract the interest of other scientists. We do so by comparing scientometric features of papers published from 1965 to 2020 that used the term ‘limnology’ against papers on similar topics but that used the term ‘lake ecology’ or ‘hydrobiology’, and to the marine counterpart of papers that used the term ‘oceanography’. We found that papers using the term limnology score worse than those of the other topics in terms of both publication output and scientific impact. Limnologists may need to use other terms in addition to ‘limnology’ to reach a broader scientific audience.

The cultural and political ecology of reed-cane craftsmanship in Lake Eber

The current study examines the interactions of people living around Lake Eber with the lake and their use of it from a cultural and political ecology perspective. In this context, fieldworks were carried out in different periods of 2018-2019. At the same time, observations and interviews covering the research subject were carried out. In the study, it was determined that aquatic plants such as common reed, reedmace, lakeshore bulrush and common cattail are cut from the Lake Eber and are used as building materials and in the production of rush mats, beach umbrellas, prayer rugs, reed pillows, floor mats (straw) and tomb mats. On the other hand, it was observed that the interest in reed-cane craftsmanship and the production of reed-cane products is decreasing every year. This is caused by drought, pollution and eutrophication processes seen in the lake. Based on the results of the study, we suggest that more field studies should be done to examine the factors that threaten the lake ecology and projects should be conducted to improve the situation in the lake.

Smoke from regional wildfires alters lake ecology

Wildfire smoke often covers areas larger than the burned area, yet the impacts of smoke on nearby aquatic ecosystems are understudied. In the summer of 2018, wildfire smoke covered Castle Lake (California, USA) for 55 days. We quantified the influence of smoke on the lake by comparing the physics, chemistry, productivity, and animal ecology in the prior four years (2014–2017) to the smoke year (2018). Smoke reduced incident ultraviolet-B (UV-B) radiation by 31% and photosynthetically active radiation (PAR) by 11%. Similarly, underwater UV-B and PAR decreased by 65 and 44%, respectively, and lake heat content decreased by 7%. While the nutrient limitation of primary production did not change, shallow production in the offshore habitat increased by 109%, likely due to a release from photoinhibition. In contrast, deep-water, primary production decreased and the deep-water peak in chlorophyll a did not develop, likely due to reduced PAR. Despite the structural changes in primary production, light, and temperature, we observed little significant change in zooplankton biomass, community composition, or migration pattern. Trout were absent from the littoral-benthic habitat during the smoke period. The duration and intensity of smoke influences light regimes, heat content, and productivity, with differing responses to consumers.

The comparative lake ecology of two allopatric Arctic Charr, Salvelinus alpinus,populations with differing life histories in Cumberland Sound, Nunavut.

The lake ecology of high-latitude fishes is strongly influenced by seasonal feeding opportunities and environmental stochasticity in Arctic environments. Arctic Charr (Salvelinus alpinus) populations are prevalent throughout the Arctic and show multiple life history strategies across their range. Unlike Old World populations the lake ecology of Arctic Charr populations on south Baffin Island remain poorly defined. We examined the comparative seasonal lake ecology of two differing Arctic Charr populations (anadromous and landlocked) in Cumberland Sound, Nunavut. Anadromous charr showed no evidence of feeding occurring within freshwater once they began seaward migrations. Anadromous charr achieve sexual maturation at a larger size and younger age than landlocked charr. Landlocked charr used more lake habitats than anadromous charr with feeding opportunities as an apparent influence on habitat selection. Landlocked charr fed year round. They adopted a cannibalistic feeding strategy in the winter but consumed a variety of prey items in the fall. Littoral habitat was found to be important to all sizes of charr in both seasons. Smaller anadromous charr (<350mm) did not use the benthic habitat. The variable ecology and form demonstrated further emphasizes the phenotypic adaptability of Arctic Charr that allows its widespread distribution in the Arctic.

Declining greenness in Arctic-boreal lakes

The highest concentration of the world’s lakes are found in Arctic-boreal regions [C. Verpoorter, T. Kutser, D. A. Seekell, L. J. Tranvik, Geophys. Res. Lett. 41, 6396–6402 (2014)], and consequently are undergoing the most rapid warming [J. E. Overland et al., Arctic Report Card (2018)]. However, the ecological response of Arctic-boreal lakes to warming remains highly uncertain. Historical trends in lake color from remote sensing observations can provide insights into changing lake ecology, yet have not been examined at the pan-Arctic scale. Here, we analyze time series of 30-m Landsat growing season composites to quantify trends in lake greenness for >4 × 105 waterbodies in boreal and Arctic western North America. We find lake greenness declined overall by 15% from the first to the last decade of analysis within the 6.3 × 106-km2 study region but with significant spatial variability. Greening declines were more likely to be found in areas also undergoing increases in air temperature and precipitation. These findings support the hypothesis that warming has increased connectivity between lakes and the land surface [A. Bring et al., J. Geophys. Res. Biogeosciences 121, 621–649 (2016)], with implications for lake carbon cycling and energy budgets. Our study provides spatially explicit information linking climate to pan-Arctic lake color changes, a finding that will help target future ecological monitoring in remote yet rapidly changing regions.

Complex phyllosphere microbiome aids in the establishment of the invasive macrophyte Hydrilla verticillata (L.) under conditions of nitrogen scarcity

Despite the low availability of nitrogen (N), the highly productive macrophyte Hydrilla verticillata (L.) is a successful invader of the littoral zones at lake Atitlán, Guatemala, with profound implications for lake ecology. To help answer the question of how Hydrilla, accompanied by the filamentous green alga Cladophora Kützing (Ulvophyceae), sustains fast growth under conditions of N scarcity, we studied the composition and potential biogeochemical function of the associated microbiomes. We combined results from next generation sequencing of associated bacterial and fungal assemblages with traditional microscopy-based taxonomical evaluation of algae and cyanobacteria. We focused on the presence of specific N2-fixing genera and their relative importance. Data on community composition are complemented with measurements of diazotrophic activity. The results expand our knowledge of the ecophysiology of these algae-plant-microbe consortia and suggest that several levels of biological complexity should be considered to fully understand aquatic plant ecology and the process of macrophyte invasions.

Lake water level response to drought in a lake-rich region explained by lake and landscape characteristics

Climate change is altering hydrologic regimes, with implications for lake water levels. While lakes within lake districts experience the same climate, lakes may exhibit differential climate vulnerability regarding water level response to drought. We took advantage of a recent drought (∼2005–2010) and estimated changes in lake area, water level, and shoreline position on 47 lakes in northern Wisconsin using high-resolution orthoimagery and hypsographic curves. We developed a model predicting water level response to drought to identify characteristics of the most vulnerable lakes in the region, which indicated that low-conductivity seepage lakes found high in the landscape, with little surrounding wetland and highly permeable soils, showed the greatest water level declines. To explore potential changes in the littoral zone, we estimated coarse woody habitat (CWH) loss during the drought and found that drainage lakes lost 0.8% CWH while seepage lakes were disproportionately impacted, with a mean loss of 40% CWH. Characterizing how lakes and lake districts respond to drought will further our understanding of how climate change may alter lake ecology via water level fluctuations.

Study of the Types of Molluscs Used by Communities, in Lake Sentani, Papua

The distribution of molluscs in Lake Sentani depends on their broad adaptability, dispersal ability, and zoogeographic history and ecological conditions. Ecological conditions in Papua have undergone many changes after the passage of special autonomy. A study on mollusk groups used by the community was carried in May-June 2018. Several government programs that require new land clearing for settlements, infrastructure development and agricultural areas have resulted in the conversion of sago forests, rivers, swamps, mangrove forests and lakes as places of interest. New settlements and shopping centers, consequently the degradation of Lake Sentani is unavoidable. Lake Sentani is currently under a lot of pressure from both internal and external factors. Some observers of lake ecology generally only conduct studies on water quality, but have not studied much of the fauna diversity, the potential of the lake's biological resources, let alone study the diversity of mollusc species and the types used by the community and the threat to the sustainability of the mollusk groups that are used. The public's understanding of the existence of Molluscs from an ecological and economic point of view has contributed greatly. From the survey results in Lake Sentani, the types used by the community are: Thiara sp. Pomacea canaliculata, Pilsbryoconcha exilis, Bellamya sp, and Faunus sp. in the in-let area. Utilization of mollusk groups as a source of family economy is also the second source of protein after fish, while in mountainous areas, certain types of mollusk shells are still used as a legally valid medium of exchange locally.