Shallow Water Lake Research Articles

Multi-year climate memory in shallow lake water levels

Landscape hydrologic memory of meteorological cycles can have an important impact on catchment hydrological responses by propagating clustering of wet or dry conditions into extreme events. The non-linear and hysteretic hydrologic response functions driven by memory are often only studied at shorter temporal scales (event, season) despite larger interannual hydrologic responses evident in some systems. Within the Canadian Boreal, lakes and lake water levels provide an important indicator that can be used to assess the role of landscape memory on catchment hydrological function. Landscape memory has also been hypothesised to control the hydrological dynamics of shallow lake ecosystems that are also important biogeochemically and ecologically. Here we combine measurements of lake water levels in 26 lakes of varying type at varying temporal frequencies within the glaciated sub-humid Boreal Plain, to examine the impact and variability of interdecadal, decadal, multi-year, and intra-annual memory on lake water levels. We show multi-annual hysteresis of precipitation-lake water levels with varied characteristics in space and time. These spatial variations in landscape memory are driven by differences in storage capacities controlled by heterogeneity in glacial landforms, wetland-forest landcover and lake properties. Thus, the propensity for drought years or wet years to persist or accumulate into extreme landscape drying or wetting varies significantly between different lake-landscape characteristics. We show how landscape memory is crucial to project lake water levels by defining spatial variability of the impact of periods of meteorological drought and deluge vital for understanding system sensitivity, duration of recovery and in turn infer resilience on Boreal Plain hydrology.

Paleoseismic Investigation of the Thousand Springs Fault, Northwestern Basin and Range, Oregon

ABSTRACT Earthquake recurrence intervals, surface-rupture extents, and interactions between faults provide insight into how faults behave and are critical for seismic hazard mitigation and earthquake forecasting. Investigating the paleoseismology of spatially related faults can reveal strain distribution and whether faults rupture as a system or independently. Summer Lake basin, a graben in the northwestern Basin and Range with four active faults (three of which have prior paleoseismic investigations), provides an opportunity to investigate fault interactions. To expand the paleoseismic record, two trenches were excavated across the previously undocumented Thousand Springs fault, exposing a normal fault zone that offsets a sequence of deep- to shallow-water lake sediments, sand dunes containing reworked Mazama ash, and other Cascades-sourced tephra. Tephra units were correlated to known units by their physical characteristics, stratigraphic sequence, glass chemistry, and two new radiocarbon dates from the uppermost lake sediments. Using trench exposures, measured vertical separations through auguring, colluvial wedges, and extrapolated offsets based on a constant sedimentation rate, we identified at least five surface-rupturing earthquakes with a total offset of 3.4 + 2/−1 m in the past ∼65 ka. The oldest event (EH5) occurred at 63.8 ± 1.5 ka, event horizon 4 at 36.2 ± 12.7 ka (which could be more than one event), and event horizon 3 at 24.6 ± 0.3 ka. Event horizon 2, a warping event at our site, is likely more than one event and occurred between 7.5 and 10 ka; and the most recent event (EH1+), most likely more than one event, occurred between 3.3 and 7.7 ka. Several events correlate, within error, with events on other faults in the Summer Lake basin, suggesting that (1) the faults generally rupture together as a system, (2) the most recent earthquake may have ruptured all faults in the region, and (3) fault rupture is influenced by the rapid regression of Lake Chewaucan (∼13 ka).

Diverse response of shallow lake water levels to decadal weather patterns in a heterogeneous glacial Boreal Plains landscape

AbstractTo examine the relative controls of landscape and climate on spatial variability, we measured water level dynamics of shallow lakes over two decades that represent both the heterogeneity of surficial geology classifications, and thus the potential range in surface and groundwater connectivity, and the long‐term weather patterns of the Boreal Plain hydrogeoclimatic setting. Large ranges in shallow lakes water levels (between 0.25 and 2 m) were observed corresponding to extremes in precipitation relative to the long‐term mean precipitation over the study period. We found low concurrence in water level dynamics among four detailed study lakes that received the same meteorological weather signal, but were located in different surficial geology texture classifications that incorporated important landscape parameters associated with lake water balance and storage. Surficial geology classification alone did not, however, distinguish between different ranges in lake water level measured in a broader synoptic survey of 26 lakes across the region. Thus, simple surficial geology classifications cannot alone be applied to classify Boreal Plain lake water level dynamics and other controls, notably landscape position, must also be considered. We further show that inter‐annual variability in lake water levels was significantly greater than seasonal variability in this hydrogeoclimatic setting. This emphasizes the need for studies of sufficient length to capture weather extremes that include periods of wetting and drying, and demonstrates how observed magnitudes of water level variability, and lake function, can be an artefact of study length and initiation date. These findings provide a foundation to test and calibrate conceptual understanding of the wider controls of lake water levels to form holistic frameworks to mitigate ecological and societal impacts due to hydrological changes under climate and anthropogenic disturbance within and between hydrogeoclimatic settings.

STRATIGRAPHY, PETROLOGY AND FACIES ASSOCIATIONS OF THE QUATERNARY SPIN KAREZ GROUP, HANNA-SPIN KAREZ AREA, QUETTA DISTRICT, PAKISTAN

The Hanna-Spin Karez area which comprises the Quaternary succession of the Spin Karez Group is located adjacent to the junction of Sulaiman and Kirthar Fold-Thrust Belts (Quetta Syntaxes), southwest of the Zarghun Trough in the northwestern Balochistan, Pakistan. The area comprises over 800 m thick conformable succession of the Quaternary age, covering surface area of ~30 km2. The succession has been named as the Spin Karez Group, which are further subdivide from base to top into three distinct lithostratigraphic units as: Hanna Lake Conglomerate, Hanna Red Clays and Spin Karez Conglomerate. The Hanna Lake Conglomerate comprises 200 m thick succession of boulder-pebble conglomerate. The Hanna Red Clays comprise over 500 m thick succession of dominantly red claystone rarely interbedded with siltstone and very fine-grained sandstone. The Spin Karez Conglomerate is composed of over 100 m thick succession of well-stratified and moderately- to well-sorted cobble/pebble conglomerate with occasional sandstone/siltstone lenses. The Triassic to Pliocene age older successions from the region's north and west provided the polymictic conglomerate, boulder to pebble size limestone, sandstone, chert, and conglomerate fragments. The Spin Karez Group comprises 15 types of gravel, sandstone and mudstone facies, which were grouped into 5 facies associations. The facies associations include braided channel deposits (FA-1), sheet-flood deposits (FA-2), floodplain deposits (FA-3), marginal lacustrine deposits (FA-4) and open-water lacustrine deposits (FA-5). The Spin Karez group evolved in three phases: i) Deposition of the Hanna Lake conglomerate started with the proximal and distal braided channel systems in the northern and southern parts of the study area respectively; ii) Deposition of the Hanna Red clays deposited in shallow lake with episodic sub-aerial exposure, providing reddish colour to the mud-dominant facies; iii) The depositional basin, once again, transformed to braided channel system, of the Spin Karez conglomerate, which evolved over the shallow water lake deposits of the Hanna Red clays. The Spin Karez group was mainly controlled by continued subsidence and regional tectonics during the Quaternary period that accommodated the space for the small shallow basin (~30 km2) that stacked depositional systems.

The rainstorm influence on ecological restoration: A novel response ecological model for an urban shallow lake

AbstractEnvironmental processes in cities and suburbs are significantly impacted by climate change. The development of reliable ecological models may successfully direct agricultural activities. Numerous models have been put forth as of late; however, because to the complexity of environmental microorganisms, their use in complex systems is still restricted. For a better understanding of the ecological restoration of an urban lake system that had been disturbed by rainfall, an improved ecological dynamic model that took into account inundation plants, phytoplankton and microorganisms was proposed based on the field survey. Observed data from a shallow urban lake with a surface area of approximately 66 600 m2 in the heart of Shunde district, Foshan, in South China, was used to validate the model. In this model, five hypotheses—phytoplankton, microorganisms, NH3‐N, COD and TP in water—were selected as experimental variables. To assess the model's correctness and dependability, the correlation coefficients (R) and root mean square error‐observations standard deviation ratio (RSR) were computed. The results from the establish model (0.446 < R < 0.985, RSR < 0.7) are very similar to those of actual observations. In addition, four microbe species (Aquabacium, Bradyrhizobium japonicum, Curvibacter and Cyanobacteria) multiplied when pollutant concentration dropped. Our model provides a useful tool for managing urban shallow water lakes by properly simulating the dynamic changes of aquatic species and microbes in urban shallow water lakes.

Diversity of microbial communities in long-term ice-covered water bodies of the Cold Pole region, Yakutia

Water bodies located in the north-east of Yakutia during the period of ice cover were studied. High-throughput sequencing of 16S rRNA gene libraries revealed a high taxonomic diversity of microbial communities in the studied ecotopes. The majority of the under-ice communities was represented by Proteobacteria, Actinobacteriota, Cyanobacteria, Verrucomicrobiota, Bacteroidota, and Planctomycetota. The difference in community diversity between deep-water lakes Labynkyr, Vodorazdelnoye, and Ulu, the source of the Labynkyr River, and shallow-water lakes Myamichi and Mertvoye, the mouth of the Labynkyr River, is shown.

IoT Sensor Network Solution for Monitoring Wind Induced Waves in Shallow Water

Abstract This case study presents a possible solution for monitoring wind induced waves in shallow water lakes. Currently widely used instruments for measuring water waves are expensive due to extreme environmental requirements and the technology used. The use of IoT solutions is not common. Water wave measurements require low power consumption and medium to long range communication. Due to the network specifications, it is not obvious that LPWAN technologies are suitable for transmitting the amount of data generated. For the devices developed, LoRaWAN was investigated as the cheapest and 5G as the most reliable network solution, with attention to energy consumption.

Stimulating effects of whooper swans’ behaviors on nutrient releasing from the sediments caused by different human feeding intensities in the swan Lake, China

In many shallow water lakes of China, as the numbers of tourists observing waterflow increases, the amount of supplemental food provided to waterflow also increases. However, little attention has been paid to the role of waterfowl’s behavior perturbation in N and P nutrients releasing from the sediment. In this study, five feeding experiments were undertaken in the Swan Lake (Shandong Province, northern China) during the wintering season and a noticeable release of nutrients in all experiments was found by the disturbance of the swan behaviors. The release of TN and TP was through three stages including the non-release stage, the rapid release stage, and the stable release stage. Moreover, supplemental food also influenced the swan behavior changes and triggered the frequency of the swans’ grazing and aggression. The aggressive behaviors among the swans stirred nutrient (N & P) releasing from sediments and altered TN and TP concentrations in the water columns, indicating that the aggressive behaviors may be a significant factor in affecting the TN and TP releasing from the sediment. Human feeding intensity (HFI) suggested > 850 g of supplemental corn can be an optimal way to aid in avoiding foraging competition among the swans to control nutrient release by three levels of human feeding intensity assessment. Our findings demonstrate that under the swans’ optimal foraging need in natural versus artificial feeding scenarios, the swans acted as biological pumps to increase nutrient release. There is a need for a systematic and evidence-based feeding strategy for swans, with greater restrictions on the provision of small food items scattered by visitors. Our study provided novel insights into the release mechanism of N and P from bioturbation and could help to inform a whooper swan conservation strategy in coastal wetlands and nature reserves.

A Holocene lacustrine record of variations in chemical weathering intensity in the Mu Us Desert, China

The Mu Us Desert is an ideal location to study environmental changes during the Late Quaternary, because of its unique characteristics. The Abaoyan (ABY) profile, a typical aeolian-lacustrine profile located at the eastern edge of the desert, was investigated in this study. A basic chronological framework was established based on a combination of radiocarbon dating by accelerator mass spectrometry and in situ sedimentary phase identification. Furthermore, changes in regional chemical weathering intensity since the Holocene were evaluated through comprehensive analysis of the collected samples in terms of grain size, loss on ignition (LOI), chromaticity, geochemical element contents, and soil micromorphology. The results showed that the ABY profile was under the influence of primary and moderate chemical weathering. Regional paleoclimatic environmental changes could be divided into four stages. During Stage I (before 12.6 ka BP; pre-Holocene), the ABY profile was dominated by aeolian sand, showing a coarse average grain size, low LOI, and high chromaticity values, which may have indicated a dry and cold period. During Stage II (12.6–10.3 ka BP; early Holocene), the ABY profile was dominated by lacustrine sediments, indicating a shallow lake water environment with strong chemical weathering and a warm and humid climate. During Stage III (10.3–4.2 ka BP), the profile was dominated by sandy peat deposits with a relatively large proportion of clay particles suggesting that the intensity of chemical weathering was relatively strong in the region during this period and the climate was mainly warm and humid. During Stage IV (after 4.2 ka BP), the sediment was dominated by aeolian sand and secondary loess, the chromaticity increased, the LOI reduced, and the regional chemical weathering intensity was weaker. The change in chemical weathering intensity in this region was inferred to be a positive response to the Holocene East Asian monsoon circulation.

Temporal and Spatial Variation Characteristics of Hydrodynamic Forces in Urban Shallow Lakes

To study the temporal and spatial variation characteristics of hydrodynamic forces in Rule Lake, a two-dimensional mathematical model of shallow water lake was established based on MIKE 21, and the flow field characteristics of Rule Lake under the action of topography, wind field and inflow were simulated and analyzed. The results show that the spatial and temporal heterogeneity of hydrodynamics in the Rule Lake area is obvious, the velocity in the lake area presents a gradient change characteristic of high in the west and low in the east, and the velocity in the middle of the lake area is greater than that in the bends of shorelines on both sides of the lake area; Under the driving of wind field, there is a reverse circulation area in the lake area. The existence of the circulation area can disturb the dead water area at the shoreline bend and improve the local water mobility; The flow velocity in summer and autumn is slightly higher than that in spring and winter. It is suggested that during the operation and maintenance period, attention should be paid to the fluidity of the water body in the southwest of the lake area, the change in water quality and the timely removal of floating garbage on the water surface.

FEEDING OF THE FISH OF BLAGODATNOE LAKE (ITURUP Island, KURIL ISLANDS) IN SUMMER

The feeding of mass fi sh species is described according to the data of ichthyological samples in June- August 2001 from Blagodatnoye Lake (Iturup Island, Kuril Islands):whitebaits of Oncorhynchus keta, Hypomesus nipponensis, Pungitius spp., Gasterosteus nipponicus, Salvelinus malma curilus, S. leucomaenis, Cottus amblystomopsis, Gymnogobius urotaenia and Tridentiger brevispinis. Whitebaits of Oncorhynchus keta, Pungitius spp. and Gasterosteus nipponicus formed the basis of catches in terms of abundance and biomass in the coastal zone of the lake. Hypomesus nipponensis is typical of shallow lake waters and has been constantly observed in the coastal area. Four ecological groups of fi sh are distinguished by the type of food. The fi rst group includes whitebaits of Oncorhynchus keta only, which are the most separated from other species in terms of the ecological spectrum of feeding. The basis of the diet of whitebaits of chum salmon (85 %) is non-aquatic insects consumed from the surface of the water. Salvelinus malma curilus and Hypomesus nipponensis exerted the greatest competitive pressure on juvenile salmon, 11 and 10 % of their diet also consisted of extra- aquatic insects, respectively. Hypomesus nipponensis is a plankto- benthophage and belongs to the second group. The basis of the ecological food spectrum of this species was formed by zooplankton (43 %) and zoobenthos (30 %). A signifi cant contribution was also characterized by fi sh eggs (17 %). The third group includes the Japanese three- spined sticklebacks, the main food of which is fi sh eggs (59 %) and zoobenthos (34 %). All other fi sh species are included in a single group of predominant benthophages. The contribution of zoobenthos in the ecological spectrum of nutrition of these fi sh varied from 57.4 % in Gymnogobius urotaenia to 100 % in Tridentiger brevispinis.

Practices for Eutrophic Shallow Lake Water Remediation and Restoration: A Critical Literature Review

Lake water has been impaired with nutrients due to the synergic action of human-made activities and climate change. This situation is increasing eutrophication around the globe faster than before, causing water degradation, loss of its uses, and water-associated economic and health effects. Following the Sustainable Development Goal 6, more precisely its target 6.6, nations are already behind schedule in protecting and restoring water-related ecosystems (i.e., rivers and lakes). As concerns with eutrophication are escalating, eutrophic water remediation practices are the keys for restoring those lake waters. Diverse methodologies have been investigated focusing on the nutrient that limit primary productivity (i.e., phosphorus), but few have been applied to in-lake eutrophic water remediation. Thus, the objective of this paper is to provide an overview and critical comments on approaches and practices for facing eutrophic lake water remediation. Information on the successful cases and possible challenges/difficulties in the peer-reviewed literature are presented. This should be useful for supporting further remediation project selection by the stakeholders involved. In summary, for a successful and durable restoration project, external nutrient inputs need to be managed, followed by holistic and region-specific methods to attenuate internal legacy nutrients that are continually released into the water column from the sediment. When aligned well with stakeholder participation and continuous monitoring, these tools are the keys to long-lasting water restoration.

Identification and environmental background of Chara remains in the Holocene sequence of Lake Peţea (NW Romania) and the possibilities of using the results in archaeobotany

The charophyte remains play an important role in the reconstruction of the hydrological characteristics (pH, water depth, stream flow, carbonate content, isotope geochemistry-water chemistry and temperature) of the former lake habitats. This is of particular importance in environmental historical studies, since the possibilities for obtaining aquatic food resources and the techniques and tools used are fundamentally influenced by these hydrological conditions. Our gyrogonite samples were recovered from the Holocene sequence of the thermalspring fed Lake Peţea NW Romania. The presence of the recovered Chara cf. hispida Linnaeus, 1753 gyrogonites marks the emergence of an oligotrophic shallow water lake system characterized by high dissolved Ca and Mg content and relatively poor plant cover in the Early Holocene. The results of previous malacological and ostracod studies also indicate the development of a shallow water lake with a muddy substrate and water temperatures above 18°C. As a warm-water lake, the local micro-environment was also home to many exploitable tree species. The charophyte remains that we recovered were from the Mesolithic level of the lake, so we were able to provide information on the hydrology of the lake for this period. Unfortunately, there have been no detailed archaeological investigations in the area to date revealing any potentially Mesolithic remains. Thus, no information is currently available on actual human occupation from the period in question.

The ecosystem resilience approach to control the invasive alien species Australian swamp stonecrop (Crassula helmsii)

The invasive Australian swamp stonecrop (Crassula helmsii) threatens species characteristic of shallow soft water lakes and pools, among others, in Europe. Anthropogenic disturbances, including restoration actions, of these ecosystems cause open niches in their littoral zones and allow C. helmsii to form dominant stands, especially under nutrient enrichment. Eradication of this invasive alien, amphibious, and clonal plant is, however, difficult and costly once a large population has established. For this reason, we here explore an ecosystem resilience approach (ERA) to control this invasive alien species. This approach includes suppressing the species by facilitating the occurrence and expansion of native vegetation. This requires a setback of C. helmsii's abundance by actively reducing its biomass, and the rehabilitation of optimal environmental conditions for native species. Our ERA study in four nature areas reveals that the introduction of native species makes the ecosystem more resilient against alien invasions, as shown by a lower abundance of this invasive plant species. Therefore, we state that ERA can effectively be applied in practice to decrease the invasibility of ecosystems by C. helmsii. Effectiveness, costs and benefits, and recommendations for application in practice are discussed. Overall, we argue that incorporating ERA in nature and water management will provide sustainable solutions in terms of biodiversity as well as more cost‐effective applications for invasive alien species prevention and control.

Spatiotemporal variations and bioaccumulation of per- and polyfluoroalkyl substances and oxidative conversion of precursors in shallow lake water

Per- and polyfluoroalkyl substances (PFAS) in water and fish from Nansi Lake, Chian and in inflowing tributaries and nearby sewage treatment plants (STPs) were determined to evaluate their distribution and bioaccumulation. The potential precursors of perfluoroalkyl acid (PFAA) present in the water were converted via hydroxyl radical oxidation. Over 3 seasons, the average concentration ranges of the 15 PFAA (∑15PFAA) concentrations in Nansi Lake, inflowing tributaries, and STPs were 22.8–70.3, 19.5–43.5, and 84.1–129 ng L−1, respectively. Perfluorooctanoic acid, perfluorooctane sulfonate (PFOS), and short-chain PFAA (perfluorocarboxlate acid <8, perfluorosulfonate acids <6) were present in high concentrations in the lake and tributaries. PFAA concentration was the lowest during the wet season and the highest during the dry season. Moreover, PFAA precursors were converted to perfluorocarboxlate acid. The concentration of C8-based precursors was higher than that of the C6-based precursors in the lake and tributaries. The concentration of PFAA in the fish liver was higher than that in fish muscles, and PFOS was the dominant chemical present in fish. Potential risk assessment based on Environment Quality Standard revealed heavy PFOS contamination in the fish. Thus, the water of Nansi Lake was heavily polluted by PFAS.

Groundwater dynamics of a lake-floodplain system: Role of groundwater flux in lake water storage subject to seasonal inundation

Groundwater behaviors in lake-floodplain systems are dynamic and complex; in particular, the role of groundwater flux in regulating lake water storage subject to strong seasonal variation is not well understood. This study addresses the contribution of groundwater flux in a large floodplain system (Poyang Lake, China), with focus on quantifying the groundwater-lake interactions at multiple time scales in high rainfall (2010) and low rainfall (2011) years using a groundwater flow model (MODFLOW). Simulated results revealed that the unconfined aquifer received approximately 8 % of the annual rainfall as groundwater recharge. Fluctuations in shallow groundwater and lake water level reflected hydraulic synchronization and hysteresis. Additionally, the diurnal variability in the groundwater-lake exchange fluxes was subject to dynamic and bidirectional patterns, and a time lag between the water exchange and rainfall was also found. For 2010 and 2011, the monthly net flux of lake infiltration into groundwater was 1.5–10.0 mm and 0.1–6.0 mm and groundwater exfiltration into lake was 1.3–9.5 mm and 0.4–2.2 mm, respectively, demonstrating a significant variation of the exchange magnitude and direction. In particular, we found that groundwater exfiltration contributed up to 55 % of lake storage change in February of 2011. The outcomes from this study indicate that groundwater can be a major component of the Poyang Lake's water balance, which suggests an important role of groundwater in regulating the lake water storage and perhaps other flood pulse systems.

Indirect herbivore biomanipulation may halt regime shift from clear to turbid after macrophyte restoration

Eutrophication transforms clear water into turbid water in shallow lakes. Current restoration techniques focus on re-establishing the clear-water state rather than on its maintenance. We investigated the response of submerged macrophytes to temporary grass carp (Ctenopharyngodon idella) and scraping snail (Bellamya aeruginosa) introductions. We also explored the impacts of herbivores on underwater light conditions to identify their long- and short-term potential to halt regime shift from clear to turbid after clear-water state reestablishment. Herbivores reduced both the biomass of submerged macrophytes and accumulated nutrients in the tissue of submerged macrophytes. This potentially avoided the pulse of endogenous nutrient release which would have exceeded the threshold required for the regime shift from clear to turbid. However, herbivores had a non-significant impact on submerged macrophyte-reduced light attenuation coefficient, which has a positive linear relationship with water chlorophyll a. Further, grass carp and snails enhanced the inhibition ratio of submerged macrophytes to phytoplankton by 3.96 and 2.13 times, respectively. Our study provides novel findings on the potential of herbivore introduction as an indirect biomanipulation tool for halting the regime shift of shallow lakes from clear to turbid after the restoration of submerged macrophytes.

Sampling and laboratory protocols to study the effects of water-level management on the littoral invertebrate fauna in deep and large temperate lakes

An integrated multidisciplinary protocol on monitoring, sampling, and laboratory procedures was developed and proposed as part of the Project "Parks Verbano Ticino" in the framework of the INTERREG V-A Italy-Switzerland 2014-2020 Cooperation Program. The project's overall goal is to evaluate the effects of water-level management (hydro-morphological stress) on both macro- and meio-fauna along the shores of Lake Maggiore, a large and deep temperate lake in northwest Italy. Because of their importance in the aquatic food web, determining how this stress affects macro- and meio-faunal assemblages is difficult. The protocol developed thus includes the evaluation of hydro-morphological impacts via the Lake Habitat Survey method, which entails monitoring of human-induced impacts and related infrastructures, followed by an in-depth evaluation of the ecological health of lake habitats via chemical analyses. The protocol then describes the sampling methods for shallow lake waters (i.e., &lt;1.5 m depths) of deep lakes, but it also provides guidance on the best time to sample, how to select sampling sites, and how to allocate sample replicates along transects. A detailed step-by-step laboratory procedure for sample treatment was provided in order to assess the structure of macro- and meio-fauna assemblages, as well as morpho-functional traits (e.g., body shape and size, biomass estimate) in response to water-level management. For the first time, a set of morphological and functional characteristics of macro- and meio-faunal taxa are proposed for comparison. The protocol for standardized trait measurement is intended to be widely used. We also proposed chironomid species-specific length-mass regression models for biomass estimation, which is important for determining growth rate and secondary production of these taxa in temperate zone lakes. Length-mass equations could shed light on the role of specific species in the flow of energy through aquatic ecosystems. The proposed protocol was evaluated by team members to ensure common utility, accuracy, and repeatability of the procedures in order for researchers and stakeholders involved in water management of lakes with similar physical characteristics to use it. The protocol, which has been adapted or simply developed to meet the needs of the Italian context, could be successfully applied to other Alpine and Mediterranean temperate, deep lakes, reservoirs, and other glacial, volcanic, and morainic lakes, as well as to a broader European context. Graphical Abstract

A Low-Complexity Underwater Acoustic Coherent Communication System for Small AUV

While underwater acoustic (UWA) communication offers a practical way to establish a wireless link with underwater vehicles, designing a UWA communication system onboard a small autonomous underwater vehicle (AUV) still poses significant challenges. As the adoption of the low-complexity, robust noncoherent communication technology is limited by low bandwidth efficiency and a low data rate, coherent UWA communication requires Doppler mitigation and channel equalization measures to achieve a relatively high data rate in a moving state. Due to the strict constraints of a small-scale AUV in terms of resources and energy consumption, it is not appropriate to use high-complexity Doppler/multipath compensation technology from the prospect of system implementation. In this paper, an efficient and low-complexity UWA differential binary phase-shift keying (DBPSK) system onboard a small AUV is proposed by simplifying the Doppler and multipath compensation. Specifically, for Doppler, the delay of the adjacent DBPSK symbols is calculated according to the Doppler estimate to facilitate delay-tuning Doppler correction. For multipath, low-complexity LMS channel equalization is incorporated with error correction coding to enable multipath mitigation. With a simple structure and low computational complexity, the proposed scheme facilitates the practical hardware implementation and system integration in the small AUV platform. The numerical simulations are conducted to assess the validity of the proposed scheme under different channel conditions and the effectiveness of the proposed scheme is further verified by two UWA communication field tests, which are performed at a practical shallow water sea and lake, respectively.

Warm Air Leads to Hazardous Ground Temperatures When Walking Dogs in Built and Natural Environments

Two case studies in Texas, one in a built environment and another in a natural setting, illustrate potential ground heat hazards when walking dogs on warm days. In the first case, temperatures of four different ground surfaces—concrete, grass, chip seal, and tar—were measured along a street in a suburban neighborhood. The study involved two morning and two afternoon surveys of 30 sampling locations where all four materials were present. Air temperatures, typical of the study area in summer, ranged from 78.0 oF (25.6 oC) in the morning to 96.1 oF (35.6 oC) in the afternoon. Ground surfaces reached much higher temperatures, exceeding 150 oF (65.6 oC), in the afternoon surveys. Median temperatures were highest in tar, followed by chip seal, concrete, and grass. The second case involved shallow lake water and various types of mud, sand, cobbles, rock fragments, and grass along a nature trail. Air temperatures ranged from 74.7 oF (23.7 oC) at 8:00 a.m. to 92.5 oF (33.6 oC) at 6:00 p.m. Ground temperatures varied considerably with material and time of day, ranging from 76.4 oF (24.7 oC) at gray cobbles and beige rock at 8:00 a.m. to 125.7 oF (52.1 oC) at brown sand at 4:00 p.m. Over the day, temperatures were highest at brown sand and lowest in water and moist sand.&#x0D;