Macrophyte Vegetation Research Articles

Feeding Habitats Selection of Waterbirds in Loktak Lake, Manipur, India

Waterbirds utilized the wetland primarily as a foraging ground and the significant predator-prey relationship between birds and fish, plants and benthic invertebrates can observe. Water depth is also an important variable factor that affects the use of wetland habitats by waterbirds for their foraging. The relationship based on water depth directly determines the accessibility of foraging habitats for waterbirds because of the restrictions of their morphology and feeding resources. The present study deals on foraging habitats of waterbirds in three guilds of Loktak Lake, Manipur. A total of 20 species of waterbirds, including resident and migratory, were analyzed for their feeding and foraging habitats. The species of the first and second guild are mainly non-vegetarian that feeds on fish and aquatic vertebrates. In the third guild, the maximum population was observed in Lesser Whistling Duck Dendrocygna javanica. Many waterfowls mostly forage the third guild that feeds on floating macrophytic vegetation. The main objectives of the study was to documented and analyse the feeding behavior and foraging habitats of waterbirds in the Loktak Lake.

Phytodiversity of the Inhulets River floodplain flora (Shyrokivskyi district)

The phytodiversity of the floodplain of the Inhulets River in the Shyrokivsky district was studied and the bioecological characteristics of flora species were compiled based on the results of systematic, biological and ecological analyzes. It was found that the flora of the floodplain landscape is represented by 329 species belonging to 69 families. The spectrum of the studied flora is dominated by perennials among biomorphs, heliomorphs – heliophytes, trophomorphs – mesotrophs, hygromorphs – mesophytes, and cenomorphs – ruderals and pratants. In the studied flora, 20 species from the Red List of Dnipro region were recorded, three of which are included in the Red Book of Ukraine: Crocus reticulatus Stev. ex Adam., Ornithogalum bouscheanum (Kunth) Aschers and Tulipa quercetorum Klokov et Zoz. Rare species included in the Red Data Book of Dnipro region were recorded in the woody and shrubby vegetation of the studied area: Viburnum lantana L., Berberis vulgaris L., Rosa maeotica Dubovik. All of this emphasizes the significant conservation value of the studied floodplain. The adventitious flora is represented by 95 species (29.6% of the total flora of the floodplain), among which five species are invasive. The macrophytic vegetation of the Inhulets floodplain is distributed in the coastal shallow waters, which are on average up to 5 meters wide and are represented by intermittent bands of air-water and submerged vegetation. Higher aquatic vegetation is characterized by intermittent-zonal and border types of overgrowth. The results of the study show a fairly high phytodiversity of the floodplain of the Ingulets River – 22.94% of the total number of flora species of the Right Bank Steppe Dnipro region, and is also important for the creation of a cadastre of plant species of Ukraine and for river restoration and management.

Level regime of the lake Bayn-Tsagan in the Holocene according to the results of palynological research (South-Eastern Transbaikalia)

According to pollen of terrestrial vegetation and micro remains of algae in the bottom sediments of the Lake Bayn-Tsagan reconstructed the vegetation of southeastern Transbaikalia in the Late Holocene. The palynological record showed a change in the lake level against the background of the absence of a dramatic change in vegetation and significant climate changes. During the accumulation of a 30 cm layer of bottom sediments, a threefold shallowing of this reservoir was recorded. In dry years, the level of the first aquifer below the surface decreased, the lake became shallow, and the abundance of higher macrophyte vegetation was overgrown with Staurastrum algae. In wet years, when the groundwater level rose, significant watering occurred. Due to increased surface runoff, the turbidity of the water in the lake increased. This contributed to an increase in the density of phytoplankton with Botryococcus.

Monitoring water spread and aquatic vegetation using earth observational data for Nani-High Altitude Lake (N-HAL) of Uttarakhand State, India

The lakes are facing anthropogenic pressure and losing its natural characteristics. Hence, the evaluation of lake water quality is a thrust area of research. The Nani-High Altitude Lake (N-HAL) was aimed to study during pre- and post-monsoon (March and October) period (2017–2022) using earth observation data based on false color composite (FCC) and spectral indices. The Sentinel-2 A/B data of 10 m spatial resolution was considered for monitoring and mapping of high-altitude lake. The FCC images were used to map and monitor changes in water spread and aquatic vegetation. Further, three spectral indices, namely, Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), and Normalized Difference Turbidity Index (NDTI), were applied to delineate water bodies and aquatic macrophytic vegetation (recorded are the Potamogeton pectinatus, Potamogeton crispus, Polygonum glabrum, Polygonum amphibium and Polygonum hydropiper (Water pepper). Results reveal that the water surface extent has changed from 2017 to 2022, depending on the pre- and post-monsoon rainfall pattern during the study period. During a flood year on 18-20, October 2021, in the area resulting into a drastic reduction in the aquatic vegetation and suspended particles. This lake needs immediate conservation and management policies.

Investigating the impact of climate change on the lake ecosystem during the late Holocene using a sedimentary record from the southern Arabian Desert, Yemen

Lake systems respond physically, chemically, and biologically to hydro-climatic change and variability, and these responses are documented in the sediments. Individual proxies and lacustrine environments may respond to climate variations in a nonlinear way, making it difficult to determine the direction and extent of a climatic shift. Here we investigate the response of lake ecosystem to climatic and environmental changes using a suite of paleo-proxies including ostracods, chironomids, and n-alkanes distribution from paleolake ‘Gayal el Bazal (Yemen)’. A previous study from this site has provided a continuous, and high-resolution dataset providing an understanding of precipitation during the last ca 1200 years, particularly during Medieval Climate Anomaly (MCA) and Little Ice Age (LIA). However, the response of the lake ecosystem to these changing hydro-climate conditions, including water-level, salinity, and productivity, remains unknown. The n-alkanes dataset shows that during pluvial interval such as the MCA, the lake experienced an increase in nutrient input resulting in enhanced aquatic productivity. Concurrently, ostracods assemblage displays an increased abundance of swimmer species (like Bradleytriebella lineata and Fabaeomiscandona cf. breuili), suggesting an indirect response between ostracods and climate shifts. The chironomid community during the MCA interval is dominated by taxa belonging to the subfamilies of Chironomini, suggesting a warm, shallow, productive environment with macrophyte vegetation. The LIA interval is marked by increased abundance of higher-chain length n-alkanes, suggesting increased contribution from higher plants. Furthermore, ostracod distribution revealed increased abundance of non-swimmer species like Vestalenula cylindrica., which thrive under saline conditions in the lake. Changes in abundances of Tanytarsini during the LIA interval, which are associated with higher oxygen levels, suggest changes in lake productivity. As a result, the overall patterns in biological indicators reveal that their individual abundance and species/tribe distribution fluctuates in response to changes in the climate and hydrological conditions.

Silicon pools, fluxes and the potential benefits of a silicon soil amendment in a nitrogen-enriched tidal marsh restoration

Tidal marshes are important sites of silicon (Si) transformation, where dissolved Si (DSi) taken up by macrophytic vegetation and algal species is converted to biogenic silica (BSi), which can accumulate in the soil, be recycled within the marsh, or be exported to adjacent coastal waters. The role of restored and created tidal marshes in these processes is not well understood, nor is the impact of nutrient enrichment at either the plant or ecosystem level. Here, Si fluxes were examined to develop a Si mass balance in a nitrogen (N)-enriched marsh created with fine-grained dredged material from the Chesapeake Bay, United States. In addition, the effectiveness of Si soil amendments to ameliorate the negative effects of excess nitrogen on Spartina alterniflora was examined through laboratory and field experiments. Silicon was exported to the estuary as DSi (49 g m−2 y−1) and BSi (35 g m−2y−1) in stoichiometric excess of nitrogen and phosphorus. Rapid recycling of Si within both marsh and the tidal creeks appeared to be important in the transformation of Si and export from the marsh. Enhanced macrophyte SiO2 tissue concentrations were observed in the field experiment, with end-of-season mean values of 2.20–2.69% SiO2 in controls and 2.49–3.24% SiO2 in amended plots, among the highest reported for S. alterniflora; however, improved plant fitness was not detected in either experiment. Thus, tidal marshes created with a fine-grained, N-rich dredged material appear to function as a rich source of Si to the restored marsh and local estuarine environment, an overlooked ecosystem service. Soil Si amendments, however, did not appear likely to alleviate N-induced stress in S. alterniflora.

Effects of Different Types of Agricultural Land Use on the Occurrence of Common Aquatic Bugs (Nepomorpha, Heteroptera) in Habitats with Slow Flowing Water in Bulgaria, Southeast Europe

Agricultural activities can have a significant impact on aquatic organisms, including aquatic insects. Most of the aquatic Heteroptera are known as moderately tolerant to low oxygen and high nutrient concentrations. Nevertheless, the complex effects of agriculture (source of both pesticides and nutrient loads) on this group are still unclear. Therefore, the relationship between six agricultural land use classes and the occurrence of common aquatic bugs in Bulgaria was studied. In order to avoid detection bias, presence-only models were applied; Maxent algorithm was used. According to the results, land use practices connected to arable land (annual crops) have stronger influence on the occurrence of the selected aquatic Heteroptera species than those connected to perennial crops (vineyards and fruit trees). Higher sensitivity to the effects of agriculture was indicated for species preferring microhabitats without macrophyte vegetation, Aphelocheirus aestivalis (Fabricius, 1794) and Micronecta griseola Horváth, 1899, compared to species preferring macrophyte dominated sites, Nepa cinerea Linnaeus, 1758, Ilyocoris cimicoides (Linnaeus, 1758) and Sigara striata (Linnaeus, 1758).

Assessment of Land use and Land Cover Change in Shallabugh Wetland of Kashmir Himalaya using Landsat Tm and Liss Iv Satellite Datasets

The increase in human activities has highlighted the need to assess land use and land cover in the Shallabugh wetland using LANDSAT TM and LISS IV satellite datasets over a 28-year period from 1990 to 2018. After ground truthing, the images were visually evaluated on screen and seven land use and land cover classes, viz. macrophytic vegetation, mixed plantation, open water, grazing land, agriculture field, built-up area, and vegetable field, were demarcated using Arc-GIS software. Out of a total area of 2552.62 ha, the maximum area was covered by macrophytic vegetation (33.87% and 32.36%) and the minimum area by vegetable field (0.77% and 1.51%) in both the years 1990 and 2018. Over the 28 year time period, land use land cover pattern showed increase in mixed plantation (2.28%), built-up (86.8%) and vegetable field (96.1%), whereas decrease was observed in macrophytic vegetation (4.4%), open water (10.3%), grazing land (28.6%), and agriculture field (2.6%). These remarkable changes were largely attributed to natural and human activities, viz., siltation, plantation and crop cultivation by local people and the construction of residential houses. Shallabugh wetland plays a role as breeding ground for a variety of waterfowl and serves as an important staging and wintering location for migratory avifauna. Land use and land cover change pose a severe threat to the Shallabugh wetland which is one of the most economically important wetland of Kashmir valley.

Sub-fossil chironomids as indicators of hydrological changes in the shallow and high-altitude lake Shen Co, Tibetan Plateau, over the past two centuries

Understanding climate and monsoonal dynamics on the Tibetan Plateau is crucial, as recent hydrological changes, evidenced by rising lake levels, will be accelerated by current global warming and may alter aquatic habitats and species inventories. This study combines chironomid assemblages with sedimentological, mineralogical and geochemical data of a short sediment core (37.5 cm) from the high-altitude (> 4,733 m asl), saline (9 g L-1) and shallow (~5 m water depth) Shen Co, located in the southern part of the central Tibetan Plateau. The predominantly littoral, species-poor (10 chironomid morphotypes) chironomid assemblages are dominated by salt-tolerant taxa, that are highly sensitive to lake level fluctuations and macrophyte vegetation dynamics, making them ideally suited for tracking lake level changes over time. Results indicate a period (from ca. 1830 to 1921 CE) of drier conditions with low runoff and high evaporation rates in the Shen Co catchment, as indicated by a dominance of low-Mg calcite and dolomite and increased Ca/Fe and Sr/Rb ratios. This resulted in a decline in lake levels, an increase in salinity and the periodic occurrence of desiccation events at the sampling site. The first chironomid morphotype to appear after the dry period is Acricotopus indet. morphotype incurvatus, which indicate still low (<2 m) but rising lake levels after 1921 CE due to increasing runoff and a lower evaporation/precipitation ratio, as reflected by coarser grain size, higher quartz content and increased TN, TOC and Al/Si ratios. A replacement of A. indet. morphotype incurvatus by Procladius is observed as lake level rise continued after 1950 CE. The highest lake level is proposed for the period since 2006 CE. From 1955 to 1960 CE and from 2011 to 2018 CE, the presence of the phytophilic taxon Psectrocladius sordidellus-type supported abundant macrophyte growth. These changes are consistent with climate reconstructions from the northern and central Tibetan Plateau, indicating warmer and wetter climate conditions since the beginning of the 20th century, which have led to an increase in lake level in a number of Tibetan lakes. Our study specifically highlights 1920 and 1950 as years with enhanced precipitation. This can be attributed to the strong, with overlapping multidecadal cycles of Westerlies and monsoon systems. This study demonstrates the significance of studying small, shallow lakes, as they frequently contain aquatic communities that respond more rapidly to the changes in the lake system. In addition, this study expands our understanding of the ecology of Tibetan chironomid morphotypes, highlighting this group’s potential as paleolimnological proxies for investigating past environmental and climatic changes.

Facies variability and depositional settings of Laguna Salada de Chiprana, an Iberian hypersaline lake

AbstractHypersaline lakes are unique depositional environments that are highly sensitive to climatic changes and anthropogenic pressures. Strong physicochemical gradients and the interplay of physical, chemical and biological depositional processes coupled to variable preservation potential associated with these environments generate highly complex sedimentary sequences. This study aimed to investigate spatio‐temporal variations throughout the last three centuries in the sedimentary sequence of Laguna Salada de Chiprana, a small, permanent hypersaline lake situated in Northeast Spain. Short sediment cores reveal a complex sedimentary sequence influenced by detrital, chemically‐induced and biogenically‐influenced depositional processes. Nine facies associated with six sedimentological units represent six periods of environmental change beginning from approximately pre‐1800 ad to the present day. They include: (i) a shallow, permanent saline lake that experienced brief periods of anoxia and drawdown between pre‐1800 ad and ca 1850 ad. This was succeeded by: (ii) increased lake levels and detrital input to the lake from ca 1850 to 1900 ad; and (iii) a fall in lake levels and the establishment of microbial mats within bottom waters fluctuating between oxic and anoxic conditions from ca 1900 to 1950 ad. (iv) From ca 1950/1960 ad, a minor increase in lake levels and colonization of the littoral and sub‐littoral zones by macrophytic vegetation occurred; followed by (v) falling lake levels and increasing salinity between 1960 and 1970 ad leading to widespread encrustation of macrophytes in the littoral zones by carbonate–evaporite precipitates. Finally (vi), from ca 1970 ad to the present day, falling lake levels, elevated salinity and widespread colonization of the lake by microbial mats characterize the sedimentary environment. Climate reconstructions and documentary evidence indicate that depositional evolution was mostly controlled by changes in farming practices and irrigation policies. Understanding Laguna Salada de Chiprana’s depositional evolution contributes to future definitions of high‐resolution palaeoenvironmental models, not only within the Iberian Peninsula but also in other locations where saline–hypersaline lakes act as a key source of palaeoenvironmental information.

Environmental Gradients Shaping the Freshwater Bryophyte Communities of Croatia (Western Balkans)

A comprehensive field survey of 527 sites on 293 watercourses across Croatia revealed 76 sites (14.42%) in which bryophytes were the dominant part of the macrophyte vegetation. Using classification and ordination analyses, we obtained five community types segregated across the gradients of several climatic, physiographic and water chemistry parameters. The Didymodon tophaceus–Apopellia endiviifolia and the Berula erecta-Cratoneuron filicinum communities were mostly confined to the clean and basic karstic rivers of the Dinaric Ecoregion under the influence of the Mediterranean climate, with the Didymodon tophaceus–Apopellia endiviifolia community being a tufa-forming community associated with the seasonally dry watercourses of small catchment areas and cascades along the larger karstic rivers, while the Berula erecta–Cratoneuton filicinum community was mostly associated with rivers with larger catchment areas and permanent flow. On the other hand, the Oxyrrhynchium hians–Chiloscyphus pallescens community and the Fissidens pusillus–Veronica beccabunga community were associated with eutrophic water restricted to small rivers of the Pannonian Ecoregion under the influence of the temperate climate and flowing over silicate bedrock. The most represented and widespread in Croatia was the Cinclidotus community, displaying the widest ecological range in the study. It was mostly associated with the relatively clean karstic rivers of large catchment areas belonging to the Dinaric Ecoregion, with the majority of the sites under the influence of a temperate climate with higher precipitation during the warm period of the year. The geographical patterns of the freshwater bryophyte communities showed that the relatively clean, fast and cold karstic rivers belonging to the Dinaric Ecoregion provide habitats that harbour a greater diversity of bryophyte communities than the watercourses of the Pannonian Ecoregion, where bryophyte-dominated communities are restricted to a small number of small lowland and semi-montane rivers and predominantly occupy periodically flooded microhabitats such as river margins.

Balancing ecosystem integrity and cultural values at sacred Lake Hora, Ethiopia: The need for conservation of wetland vegetation

AbstractAlthough macrophytes represent important habitats for the plankton communities of shallow lakes and ponds, the role of littoral macrophyte patches in deep crater lakes is not well described. The objective of the present study was to investigate the role of littoral macrophyte vegetation in structuring phytoplankton and zooplankton communities and, therefore, sustaining ecological integrity in a deep tropical crater lake (Hora Lake, Ethiopia). The lake has a surface area of 1.03 km2 and a mean depth of 16.5 m. The area surrounding the lake is a prime location for the celebration of the Oromo thanksgiving festival (Irreecha), which is inscribed by the United Nations Educational, Scientific and Cultural Organization (UNESCO) as an intangible cultural heritage, and also considered sacred by the Oromo people. Measurements of physical, chemical and biological parameters were conducted at fifteen sampling sites in both the littoral and central parts of the lake during the dry and wet seasons in 2017. A total of 28 phytoplankton and 19 zooplankton genera were identified. The phytoplankton and zooplankton communities were dominated by cyanobacteria and rotifers, respectively, at the open water sites. The wetland vegetation was found to be important in reducing potentially toxic and unsightly cyanobacteria. The submerged and emergent vegetation also served as refugia for zooplankton during the wet and dry seasons, respectively. Crustaceans accounted for about 30–45% of the total zooplankton abundance within the vegetation fringes. Their abundance decreased to 5% in the non‐vegetated areas, wherein the community was dominated by rotifers. As the population around the lake, particularly during the festival, may damage the aquatic vegetation, their access to the shoreline should be regulated for conservation and sanitary reasons (e.g. to reduce cyanobacteria growths).

Sedimentology and Stratigraphy of a Large, Pre-Vegetation Deltaic Complex

The operation of depositional processes in fluvial systems prior to the development of land-based, macrophyte vegetation has undergone considerable research. The differences in sedimentation in the channels and floodplains compared to post-vegetation systems should result in differences also existing in the deposits developed where the rivers debouch their loads into standing bodies of water. These deltaic deposits have been studied relatively less. The 1.4 Ga Kama Hill and Outan Island Formations of the Sibley Group, northwestern Ontario, provide a site to further investigate these potential differences. Four totally cored drill holes intersect this 340 m thick, prograding, deltaic to fluvial succession. It is divisible into eight lithofacies associations representing environments ranging from prodelta to the delta-top floodplain-channel assemblage. The sub-aqueous portion of the succession is composed of two thick progradational delta lobes probably caused by: deposition induced regression followed by a condensed sequence due to channel avulsion with distal repositioning, and finally channel avulsion with proximal repositioning driving another depositional induced regression. Large-scale sequence stratigraphic nomenclature does not properly describe this succession. At a smaller scale, members of progradational parasequence sets decrease in thickness from the prodelta to upper distributary-mouth bars. The deltaic deposits are compared to the modern, large Mississippi deltaic system. Sub-aqueous sub-environments are similar to this, except: 1) the lack of infauna bioturbation leads to better preservation of Sibley Delta sedimentary structures; 2) scarce organic sediment does not allow reducing diagenetic reactions, thus preserving the highly oxidized nature of the fluvial sediments; 3) the Sibley distributary-mouth bars have more medium- and coarse-grained sand than the Mississippi bars; 4) the Sibley distributary-mouth bars have abundant thick, massive, non-graded, normal graded and reverse graded sandstones, likely the result of high-discharge slurry-flows from the fluvial channels; 5) the lack of macrophytes (coastal marshes) complicates interpreting the transition from bar tops to sub-aerial environments; 6) the abandonment phase of bay-fill progradational parasequences is further condensed due to the lack of organic deposits. However, the considerable similarities between the Sibley Delta and the Mississippi Delta denote that not all pre-vegetation deltas conform to general braid and fan delta models.

How Do Specific Environmental Conditions in Canals Affect the Structure and Variability of the Zooplankton Community?

The present study investigates the responses of zooplankton (including changes in their structure and diversity) to physicochemical and biological parameters in two artificial waterways. Water samples were collected monthly from the Bydgoszcz Canal, the Noteć Canal, and the Brda River during the growing season of April–October 2019. We analyzed how selected parameters (including water temperature, Secchi disk visibility, oxygen concentration, conductivity, and pH, as well as nitrate, phosphate, and chl-a concentrations) affected seasonal variations in zooplankton diversity (T) and density (N). In total, we recorded 98 species, and average zooplankton density was 320 ind/L. At all sites, the same zooplankton species were dominant: Keratella cochlearis among rotifers and the Cladocera Bosmina longirostris among crustaceans. Rotifers dominated qualitatively and quantitatively over crustaceans. Zooplankton density and biomass, as well as the number of zooplankton species, were higher in the Bydgoszcz Canal than in the Brda River or the Noteć Canal. This may be connected to the locks on the Bydgoszcz Canal slowing down water flow, thereby increasing macrophyte vegetation, which creates ecological niches supporting zooplankton development.

Using dredged sediments to support wetland plant development in a constructed delta lake

Restoration efforts take place at large scales to improve the ecological value of degraded, modified river deltas. To anticipate on the implications of using dredged, estuarine sediment to restore wetlands in river deltas, we studied the development of Typha latifolia (cattail) and Phragmites australis (common reed) on two designated dredged sediments, virgin Holocene clay (clay) and eroded clay (mud), under different water levels (inundated, saturated, and moist) in a mesocosm experiment. The mud sediment contained about two times higher Fe, S, and P content and four times higher N-total content compared to clay sediment. The organic content was comparable for both sediments. Sediment type influenced germination and shoot growth of T. latifolia, which were both higher on clay compared to mud, but did not influence germination and initial growth of P. australis. Water level treatment effects on plant response were limited to inundation conditions only; this condition strongly reduced P. australis seedling and shoot development. Both species developed significantly more above- and belowground biomass when growing in mud compared to clay, however, their nutrient content was comparable on both sediment types. Overall, T. latifolia development was more strongly influenced by sediment composition compared to P. australis, but the latter species is more vulnerable to higher water levels during early stages of development. We conclude that both dredged sediment types are suitable as sediment for developing macrophyte vegetation.

Influence of dense macrophyte vegetation and total gas saturation on the performance of acoustic telemetry

BackgroundAcoustic telemetry is widely used as a method for high resolution monitoring of aquatic animal movement to investigate relationships between individual animals and their environment. In shallow freshwater ecosystem, aquatic macrophytes are common and their presence increases habitat complexity and baffles sound propagation. These properties may be likely to affect the performance of acoustic telemetry, however, to date this issue has received little attention, when studying the ecology of movements of fishes in and around the important macrophyte habitats. Here, we conducted a range-test study in a freshwater riverine ecosystem, with mass development of the aquatic macrophyte Juncus bulbosus (L.), to assess how dense macrophytes impact detection probability, detection range, and performance of a three-dimensional receiver positioning system. Supersaturation of gas frequently occurs at the study site as a by-product of upstream hydroelectric power generation and gave a unique opportunity to investigate how total gas saturation affects the performance of acoustic telemetry. We also investigated the influence of environmental conditions (i.e., day-of-year, time of day, average water level above J. bulbosus) on detection probability together with vertical position of transmitters and location inside or outside macrophytes.ResultsThe detection probability and range were generally low for transmitters in and outside J. bulbosus stands, with mean hourly detection probabilities ranging from 1.18 to 5% and detection ranges between 17.26 m ± 0.74. The interaction between total macrophyte biomass and distance to receiver reduced the detection probability and detection range substantially. Detection probability further decreased with increasing total gas saturation, and transmitters positioned near the sediment and close to the surface also had lower detection probabilities compared to receivers in the middle of the water column. Finally, the low detection probability affected position estimates, where only 23% of the detections could be positioned using the average positioning estimation method and positional accuracy and precision were low ranging from 1.48 to 164.8 m and 0 to 50.1 m, respectively.ConclusionsOur findings demonstrate the impact of macrophytes and total gas saturation on detection probability and range of acoustic transmitters in a shallow ecosystem, where tagged fish are unlikely to be detected by receivers or positioned. These results emphasise that in situ range testing is strongly needed before determining the density and design of receiver array when performing acoustic telemetry studies in shallow ecosystems.

Water level changes in Lake Erie drive 21st century CO2 and CH4 fluxes from a coastal temperate wetland

Wetland water depth influences microbial and plant communities, which can alter the above- and below-ground carbon cycling of a wetland. Wetland water depths are likely to change due to shifting precipitation patterns, which will affect projections of greenhouse gas emissions; however, these effects are rarely incorporated into wetland greenhouse gas models. Seeking to address this gap, we used a mechanistic model, ecosys, to simulate a range of water depth scenarios in a temperate wetland, and analyzed simulated predictions of carbon dioxide (CO2) and methane (CH4) fluxes over the 21st century. We tested our model using eddy covariance measurements of CO2 and CH4 fluxes collected at the Old Woman Creek National Estuarine Research Reserve (OWC) during 2015 and 2016. OWC is a lacustrine, estuarine, freshwater, mineral-soil marsh. An empirical model found that the wetland water depth is highly dependent on the water depth of the nearby Lake Erie. Future wetland surface water depths were modeled based on projection of Lake Erie's water depth using four separate NOAA projections, resulting in four wetland water-depth scenarios. Two of the four 21st century projections for Lake Erie water depths used in this study indicated that the water depth of the wetland would remain nearly steady; however, the other two indicated decreases in the wetland water depth. In our scenario where the wetland dries out, we project the wetland's climatological warming effect will decrease due to smaller CH4 fluxes to the atmosphere and larger CO2 uptake by the wetland. We also found that increased water level can lower emissions by shifting the site towards more open water areas, which have lower CH4 emissions. We found that decreased water depths would cause more widespread colonization of the wetland by macrophyte vegetation. Using an empirical relationship, we also found that further drying could result in other, non-wetland vegetation to emerge, dramatically altering soil carbon cycling. In three of our four projections, we found that in general the magnitude of CO2 and CH4 fluxes steadily increase over the next 100 years in response to higher temperatures. However, in our driest simulations, we projected a different response due to increased oxidation of soil carbon, with CH4 emissions decreasing substantially from an annual cumulative peak of 224.6 to a minimum of 104.7 gC m−2 year−1. In that same simulation, net cumulative flux of CO2 changed from being a sink of 56.5 gC m−2 year−1 to a source of 369.6 gC m−2 year−1 over the same period, despite a temperature increase from 13.7 °C to 14.2 °C. This temperature shift in our other three cases with greater water depths increased the source strength of CH4 and the sink strength of CO2.We conclude that the magnitude of wetland greenhouse-gas fluxes depended on the water depth primarily as it affected the areal percentage of the wetland available for plant colonization, but dramatic decreases in water depths could cause significant reductions in the wetland CH4 fluxes, while simultaneously altering the wetland vegetation.

Aquatic Macrophyte Vegetation Promotes Taxonomic and Functional Diversity of Odonata Assemblages in Intermittent Karst Rivers in the Mediterranean

Assemblages of adult Odonata were studied in four intermittent karst rivers encompassing macrophyte-rich (MRH) and macrophyte-poor habitats (MPH) in southern Europe, where temporary lotic habitats are the predominant freshwater type but are still understudied. With a total of 25 recorded species, the studied habitats support species-rich Odonata assemblages, as already shown for intermittent rivers in the Mediterranean. Aquatic macrophyte abundance, conductivity, and water velocity are the most significant determinants of Odonata assemblages in the studied IRES. MRH promote higher Odonata abundance and the taxonomic and functional diversity of their assemblages compared to the MPH. Odonata assemblages in MRH are characterized by higher values of body size and a higher share of species preferring lentic and temporary hydrological conditions. Moreover, their assemblages are characterized by various patterns of nymphal development and drought resilience strategies. In contrast, MPH are preferred by lotic species, with nymphal development all year round and with no specific drought-resisting strategies. Our results contribute to the knowledge of diversity and ecological requirements of dragonflies and damselflies in IRES habitats, which could provide scientific background for future conservation activities and bioassessment protocols of such habitats and their biota.

Zasolenie strefy hyporeicznej rzeki Moszczenicy w rejonie wysadu solnego Rogóźno

Zasolenie strefy hyporeicznej rzeki Moszczenicy w rejonie wysadu solnego Rogóźno

Epiphyton in Agricultural Streams: Structural Control and Comparison to Epilithon

Stream biofilms play an important role in the structure, functioning, and integrity of agricultural streams. In many lowland streams, macrophyte vegetation is abundant and functions as an important substrate for biofilm (epiphyton) in addition to the gravel and stone substrate for epilithon on the stream bed. We expect that reach-scale habitat conditions in streams (e.g., nutrient availability, hydraulic conditions) affect the epiphyton and epilithon biomass and composition, and that this effect will be substrate-specific (macrophytes and stones). The objectives of our study were (i) to describe concurrent changes in epiphyton and epilithon biomass and composition over a year in agricultural streams, and (ii) to determine the substrate specific reach-scale habitat drivers for the epiphyton and epilithon structure. We monitored epiphyton and epilithon biofilm biomass and composition at three-week intervals and reach-scale environmental conditions daily during a year for two agricultural steams. The results showed that epiphyton and epilithon communities differed in biomass, having high substrate specific biomass in epilithon compared to epiphyton. Epiphyton was mainly composed of diatom and green algae, while cyanobacteria were more important in epilithon, and the diatom species composition varied between the two biofilm types. Epiphyton structural properties were less influenced by reach-scale hydrology and nutrient availability compared to epilithon. The overall explanatory power of the measured environmental variables was low, probably due to micro-scale habitat effects and interactive processes within stream biofilms. Knowledge of biofilm control in agricultural streams is important in order to improve management strategies, and future studies should improve the understanding of micro-scale habitat conditions, interactive relationships within biofilms and between the biofilm and the substrates.