Macrophyte-dominated Shallow Lake Research Articles

Abrupt shift in the organic matter input to sediments in Lake Liangzi, a typical macrophyte-dominated shallow lake in Eastern China, and its response to anthropogenic impacts

Understanding the historical variations in organic matter (OM) input to lake sediments and the possible mechanisms regulating this phenomenon is important for studying carbon cycling and burial in lake systems; however, this topic remains poorly addressed for macrophyte-dominated lakes. To bridge these gaps, we analyzed bulk OM and molecular geochemical proxies in a dated sediment core from Lake Liangzi, a typical submerged macrophyte-dominated lake in East China, to infer changes in OM input to sediments over the past 169 years due to the intensification of human activities in the catchment. A relatively primitive OM input pattern was observed in ca. 1841–1965, during which the lowest hydrogen index (HI), short-chain n-alkane abundance, and n-C17/n-C16 alkane indicated minimal input from phytoplankton, whereas the high Paq (proxy of aquatic macrophyte input) and long-chain n-alkane abundance suggested dominant and subordinate inputs from submerged and emergent macrophytes, respectively. OM input transitioned during ca. 1965–1993, with the highest Paq and lowest long-chain n-alkane abundance, indicating an increase of submerged macrophyte input and concurrent decline of emergent macrophyte input, probably caused by hydrological regulation practices and land reclamation in the 1960s, respectively. A further shift in OM input was observed since ca. 1993, characterized by the beginning of an increase in phytoplankton input, as indicated by the greater HI, short-chain n-alkane abundance, and n-C17/n-C16 alkane in sediments. Moreover, a lower Paq and higher abundance of long-chain n-alkanes indicated a decline in input from submerged macrophytes and an elevated input from terrestrial plants. The increase in αβ-hopane abundance and homohopane index value indicated that petroleum-sourced OM was first introduced into the sediments. The causes of these OM input changes included nutrient influx associated with domestic and industrial discharge, aquaculture within the lake, and widespread deforestation and land clearance in the catchment.

Trophic transfer of antibiotics in the benthic-pelagic coupling foodweb in a macrophyte-dominated shallow lake: The importance of pelagic-benthic coupling strength and baseline organism

In lake ecosystems, pelagic-benthic coupling strength (PBCS) is closely related to foodweb structure and pollutant transport. However, the trophic transfer of antibiotics in a benthic-pelagic coupling foodweb (BPCFW) and the manner in which PBCS influences the trophic magnification factor (TMFs) of antibiotics is still not well understood in the whole lake. Herein, the trophic transfer behavior of 12 quinolone antibiotics (QNs) in the BPCFW of Baiyangdian Lake were studied during the period of 2018–2019. It was revealed that 24 dominant species were contained in the BPCFW, and the trophic level was 0.42–2.94. Seven QNs were detected in organisms, the detection frequencies of ofloxacin (OFL), flumequine (FLU), norfloxacin (NOR), and enrofloxacin (ENR) were higher than other QNs. The ∑QN concentration in all species was 11.3–321 ng/g dw. The TMFs for ENR and NOR were trophic magnification, while for FLU/OFL it was trophic dilution. The PBCS showed spatial-temporal variation, with a range of 0.6977–0.7910. The TMFs of ENR, FLU, and OFL were significantly positively correlated with PBCS. Phytoplankton and macrophyte biomasses showed indirect impact on the TMFs of QNs by directly influencing the PBCS. Therefore, the PBCS was the direct influencing factor for the TMFs of chemicals.

Effects of herbivorous fish on shallow lake ecosystems increase at moderate nutrient conditions

Submerged macrophytes are vital in shallow lakes, as they provide critical ecosystem functions and services and can stabilize the clear-water conditions by various mechanisms. Nutrient enrichment reduces the resilience of macrophyte dominance in shallow lakes, thereby making them susceptible to shifts towards phytoplankton dominance following perturbations. Here, we conducted a mesocosm experiment to examine the individual and combined effects of nutrient enrichment and the addition of grass carp (Ctenopharyngodon idella) on the abundance of submerged macrophytes, epiphyton, and phytoplankton. We hypothesized that moderate nutrient enrichment facilitates macrophyte abundance, but also phytoplankton abundance after macrophyte removal by herbivorous fish. Our data showed that herbivory by grass carp could trigger a shift from macrophytes to algal dominance in mesocosms with moderate nutrient concentrations, but not in those with low nutrient concentrations. Moderate nutrient enrichment alone promoted submerged macrophyte growth, whereas the introduction of grass carp induced a collapse of submerged macrophytes regardless of nutrient conditions. Moreover, the introduction of grass carp showed more negative effects on light conditions of the water column in mesocosms with moderate nutrient concentrations compared to those with low nutrient concentrations. A recovery of submerged macrophytes might thus be limited by low light availability in lakes with moderate nutrient conditions suffering grass carp perturbation. Our results suggest that submerged macrophyte-dominated shallow lakes with moderate nutrient conditions are vulnerable to perturbation by herbivorous fish such as grass carp. In turn, managing the abundance of herbivores in these lakes can support the dominance of macrophytes and associated clear water conditions.

Interspecific relationships between submerged and emergent aquatic plants along a nitrogen gradient in a mesocosm experiment

The responses of plant populations and communities to environmental factors play a key role in the ecological protection and restoration of lakes. However, little is known about how interspecific relationships respond to environmental gradients, especially for relationships between different growth forms such as submerged and emergent aquatic plants in shallow lakes, which can further affect species composition as community dynamics. We carried out a mesocosm experiment to investigate the responses of two focal aquatic plants (Ceratophyllum demersum and Phragmites australis) at two density levels and six levels of total nitrogen (TN) levels. Our results suggested that interspecific competition exist between C. demersum and P. australis, especially at high nitrogen levels. The competition relationship was mainly influenced by variations of relative growth rates of C. demersum and population density of P. australis along the nitrogen gradient. The interspecific neighbor effect on C. demersum shifted from facilitation to competition as TN increased, whereas on P. australis showed no significant facilitation effect along the TN gradient. Ceratophyllum demersum and P. australis adopted stress-tolerance and competition strategies for nitrogen, respectively, in co-culture. As a result, the dominant species in the plant community is likely to shift from the submerged macrophyte (C. demersum) to the emergent macrophyte (P. australis) as TN increases. Moderate TN (2.5 mg/L) can potentially support high biodiversity in macrophyte-dominated shallow lakes in our study. This finding has implications for different community composition at different nitrogen levels. Furthermore, it has important implications for protecting biodiversity and guiding vegetation restoration in shallow lakes.

Study on Temporal and Spatial Distribution of Biogenic Elements of Sediment in Baiyangdian Lake

Baiyangdian Lake is the largest macrophyte-dominated shallow lake in North China and the most important ecological barrier area in the Xiong’an New Area. Since the 1980s, the surface water of Baiyangdian Lake has been in a state of eutrophication for a long time due to high nitrogen and phosphorus content. Under the background of the gradual implementation of the New Area Planning Outline, the load of nitrogen and phosphorus from exogenous sources into the lake has been gradually controlled, and the nitrogen and phosphorus enriched in the sediment has increasingly become the main factor affecting water quality. Therefore, this study focused on the vertical and lateral distribution differences of total organic carbon, total nitrogen and total phosphorus contents in Baiyangdian Lake sediments. Meanwhile, combined with sedimentary years, the enrichment characteristics of nitrogen and phosphorus in different ages and their consistency with the change of total organic carbon content were analyzed. The study can provide some scientific reference for controlling the accumulation of nitrogen and phosphorus in Baiyangdian sediment and scientifically and orderly dredging.

Bioaccumulation, trophic transfer, and human health risk of quinolones antibiotics in the benthic food web from a macrophyte-dominated shallow lake, North China

The bioaccumulation and trophic transfer of 12 Quinolones (QNs) have been studied in a macrophyte dominated lake-Baiyangdian Lake, China. QNs concentrations were detected in surface water, sediments, and 25 biological samples. The average concentrations of QNs varied from 3.01 ng/L for Oxolinic Acid (OXO) to 174 ng/L for Flumequine (FLU) in water, 3.28 ng/g (dry weight, dw) for OXO to 97.0 ng/g (dw) for FLU in sediments, and from 2.88 ng/g (dw) for Pipemidic Acid (PIP) to 37.7 ng/g (dw) for FLU in biological samples. The values of bioconcentration factors (BCFs) or bioaccumulation factors (BAFs) (in the range of 98.0–723 L/kg) and biota sediment accumulation factor (BSAFs) (in the range of 0.000300–0.124) were indicated that low bioaccumulation ability of target QNs in biological species. Due to the detected frequencies of FLU, Enrofloxacin (ENR), Norfloxacin (NOR), and Ofloxacin (OFL) were higher than 50%, the trophic magnification factors (TMFs) values for those QNs were calculated from three different habitats. The TMFs for those QNs were ranged from 0.840 to 1.10. Thereinto, ENR and NOR were appeared trophic magnification, while FLU and OFL were appeared trophic dilution in the food web of Baiyangdian Lake. Although the TMFs values of QNs were not showed significantly difference among three habitats, the TMFs values of those QNs showed significantly difference between the foodweb with macrophyte species and without macrophyte species. Except FLU, the other TMFs values of these QNs without macrophyte species (in the range of 0.700–1.01) were lower than the TMFs for QNs with macrophyte species. Finally, the results of human health risk for QNs suggested that consumption of fish from Baiyangdian Lake with a considerable risk, thus more standard and residue limits of QNs should be set to decrease the human health risk around this region. Capsule abstractThe spatial variation of bioaccumulation, trophic transfer, and human health risk for 12 QNs has been studied in the benthic foodweb from a macrophyte-dominated shallow lake.

Integrated ecosystem services-based calculation of ecological water demand for a macrophyte-dominated shallow lake

Macrophyte-dominated shallow lakes are one of the commonest freshwater wetlands in plain area, and composed of lake, marsh, and terrestrial land. They are, however, facing great ecological risks of serious pollution and wetland degradation caused by the shortage of ecological water demand. Baiyangdian is the largest shallow lake in northern China. It is of great importance to ecosystem services in Xiongan New Area, China, providing food production, climate regulation and other functions. Water storage in Baiyangdian comprises components of lake, marsh and terrestrial land, each of which supplies a different ecosystem service value (ESV). As a result, the total ESV of a macrophyte-dominated shallow lake changes according to water storage fluctuation. In this study, we estimated the total and individual land ESVs (lake, marsh, and terrestrial land) of the Baiyangdian. We also quantified the relationship between ESV and water storage in the macrophyte-dominated shallow lake, taking water level as the indicator. The optimum water level varied, corresponding to the highest ESV of each type of land, and an optimum water level of 8.2 m was identified as achieving the highest total ESV of the Baiyangdian (6.697 billion yuan). We also divided ecosystem services into four functional categories: provisioning, regulating, supporting, and cultural and found these components also changed with water storage changes in the macrophyte-dominated shallow lake. Fluctuation in the total ESV was attributed mainly to the marshland because of its huge supply capacity for support and cultural services. An optimum water level range of 7.9–8.5 m existed where ESV was most balance among different functional categories. After considering the functional and land cover components of total ESV of the Baiyangdian, we recommend an optimum water level of 8.2 m, and emphasize the importance of including ESV in calculations of ecological water demand.

Spatio-temporal variations of benthic macroinvertebrates and the driving environmental variables in a shallow lake

Abstract Shallow lakes widely distributed in middle and lower reaches of watershed are easily multi-stressed by natural forces and human activities. Here, spatio-temporal variations of macroinvertebrate community and their influential variables in a typical large macrophyte-dominated shallow lake--Baiyangdian Lake were studied, using three-year in-situ observational data of spring, summer, and autumn. In total, ten environmental variables and five biological indices were measured for the six sites from each of the two habitat types, semi-natural habitat and disturbed habitat divided by their different exposures to human activities. Disturbed habitat had deeper mean water depth, lower mean transparency, and higher mean concentrations of DO, TN, NH4-N, NO3-N, and COD than that of semi-natural habitat regardless of seasons. Biological metrics indicate lower family-level richness but higher community tolerance level in disturbed habitat in spring and summer, but the results were close in autumn. The present of Lestidae and Gammaridae was a significant determination of semi-natural habitat. Redundancy analyses showed community temporal distribution was mainly driven by temperature, water depth, and pH that greatly influenced by natural forces, while spatial distribution was mainly driven by TN and transparency that greatly influenced by human activity. Regarding averaged data over the same year, season, and habitat, richness and Shannon-Weiner index had significant Pearson linear correlation with transparency (r = 0.521 and r = 0.541, p

A Paleoenvironmental Study Tracking Eutrophication, Mining Pollution, and Climate Change in Niven Lake, the First Sewage Lagoon of Yellowknife (Northwest Territories) + Supplementary Appendix 1 (See Article Tools)

Niven Lake was the first wastewater disposal site for the City of Yellowknife (Northwest Territories, Canada), receiving domestic sewage for more than 30 years. Here, we used a high-resolution sediment core to track past sewage inputs to Niven Lake by comparing changes in sedimentary sterols and three diagnostic ratios for human fecal contamination, as well as biological assemblages and overall lake production, with the known history of sewage inputs to the lake from 1948 to 1981. Coprostanol, often considered the best indicator of human fecal contamination, increased by ~8% between depths of 7.5 cm and 5 cm (~1950 to 1981) and was more reliable in tracking sewage contamination than diagnostic sterol ratios. Muted responses in subfossil diatom and chironomid assemblages were noted during the time of sewage inputs, and similar responses have been reported in other eutrophic Arctic sites, as well as in many macrophyte-dominated shallow lakes in general. More marked shifts in diatoms and chironomids occurred a decade after the end of sewage inputs, in the 1990s, a time that closely aligned with the warmest years on record for Yellowknife. This post–sewage era response was indicative of anoxia and possibly of positive feedback from internal phosphorus loading. The response may have been facilitated by recent climate warming, resulting in a lagging recovery from eutrophication. Changes in the diatoms and chironomids of Niven Lake were also indicative of metal pollution, suggesting that the lake has experienced the compounding effects of arsenic contamination from nearby gold mining.

The effect of epiphytic macroinvertebrates on microbial communities in different types of macrophyte-dominated shallow lakes

Complex interactions between epiphytic fauna and microbial food webs in periphyton are vital to the ecosystem ecology of shallow lakes. However, little is known about how different types of macrophyte dominated lakes may influence microbial and metazoan communities. The goal of the present study was to examine the impact of metazoan on microbial food web in three different types of lakes (Stratiotes-dominated,Ceratophyllum-dominated andPotamogeton-dominated). The results of this study suggest a strong correlations between chironomid larvae, small Metazoa and microbial communities in the periphyton of macrophyte-dominated lakes. Weak relations between food web components were found in thePotamogeton-dominated andCeratophyllum-dominated lakes, where environmental variables explained the bulk of the total variance in periphyton abundance, whereas strong predator-prey relations were noted in theStratiotes-dominated lake, where environmental variables had a minor role in the total variance in periphyton abundance. Our study contributes to knowledge of the functioning of eutrophic lakes in the current era of increasing eutrophication caused by climate change and human activity.

Distribution of epiphytic diatoms on five macrophytes from a Pampean shallow lake: host-specificity and implications for paleoenvironmental reconstructions

Epiphytic diatoms are an important component of death and fossil assemblages in macrophyte-dominated shallow lakes. In the Argentinean Pampas, the lack of studies on the composition, diversity and distribution of epiphytic diatoms limits the extent of the paleoenvironmental inferences that can be made from their fossil record. We studied the composition of epiphytic diatom biofilms living on five macrophytes in a Pampean shallow lake (Nahuel Rucá, Buenos Aires Province). Samples of emergent, free-floating, rooted-floating and submersed macrophytes were collected in triplicate over one year and analyzed for diatoms. Epiphytic assemblages on the free-floating species Azolla filiculoides and Ricciocarpus natans were dominated by Lemnicola hungarica, whereas the remaining macrophytes (the emergent Schoenoplectus californicus, the submersed Ceratophyllum demersum and the rooted-floating Hydrocotyle ranunculoides) were dominated by Cocconeis placentula. Although all assemblages were dominated by epiphytic taxa, low proportions of planktonic and benthic taxa were also recorded. Composition, diversity, richness and evenness of diatom assemblages found on free-floating macrophytes differed significantly from the rest of the samples analyzed. The strong association of the epiphytic diatom, L. hungarica, with free-floating macrophytes, together with the high dominance of C. placentula on emergent and submersed plants provides a potential method for inferring past fluctuations in aquatic vegetation coverage in the palaeolimnological record of Pampean shallow lakes.

Effect of water chemistry on zooplanktonic and microbial communities across freshwater ecotones in different macrophyte-dominated shallow lakes

<p>Complex interactions between zooplankton and microbial food webs are vital to the ecosystem ecology of shallow lakes. However, little is known about how horizontal changes in environmental conditions may influence microbial and metazoan communities in shallow lakes. The specific goals of the study were i) to describe environmental variables responsible for the distribution of bacteria, flagellates, ciliates and crustaceans in an adjacent canal, ecotone and reservoir (littoral-pelagic zone) in two different types of lakes (<em>Ceratophyllum</em>-dominated and <em>Potamogeton</em>-dominated lakes); ii) to determine whether the contact zone waters differ in hydrochemical and biological terms from the waters of the canal and the open water zone; iii) and to evaluate the influence of particular macro-habitats (canal, canal/reservoir, littoral and pelagic zone) on the interactions between components of the planktonic food web. We studied four shallow, eutrophic lakes in Polesie Lubelskie (eastern Poland). The highest diversity and abundance of microorganisms and crustaceans were observed in the canal-reservoir contact zone, while the lowest values were noted in the pelagic zone. Hence, the contact zone in the investigated lakes could fulfil the function of an ecotone, distinguished by a significant increase in biodiversity, abundance, and species specificity of micro- and macroorganisms. Weak relations between food web components were found in the <em>Ceratophyllum</em>-dominated lakes, where environmental variables explained the bulk of the total variance in plankton abundance, whereas in the <em>Potamogeton</em>-dominated lakes, where environmental variables had a minor role in the total variance in plankton abundance, strong predator-prey relations were noted. Spatial structure of habitats proved to be another important factor for relationships between food web components, as our study indicated that habitat complexity can reduce negative correlations between food web components. Our study contributes to knowledge of the functioning of eutrophic lakes in the current era of increasing eutrophication caused by climate change and human activity.</p>

Microbial pelagic metabolism and CDOM characterization in a phytoplankton-dominated versus a macrophyte-dominated shallow lake

Fil: Torremorell, Ana Maria. Universidad Nacional de Lujan. Departamento de Ciencias Basicas; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina

Comparison of the spatial and temporal variability of macroinvertebrate and periphyton-based metrics in a macrophyte-dominated shallow lake

The influence of spatial differences, which are caused by different anthropogenic disturbances, and temporal changes, which are caused by natural conditions, on macroinvertebrates with periphyton communities in Baiyangdian Lake was compared. Periphyton and macrobenthos assemblage samples were simultaneously collected on four occasions during 2009 and 2010. Based on the physical and chemical attributes in the water and sediment, the 8 sampling sites can be divided into 5 habitat types by using cluster analysis. According to coefficients variation analysis (CV), three primary conclusions can be drawn: (1) the metrics of Hilsenhoff Biotic Index (HBI), Percent Tolerant Taxa (PTT), Percent dominant taxon (PDT), and community loss index (CLI), based on macroinvertebrates, and the metrics of algal density (AD), the proportion of chlorophyta (CHL), and the proportion of cyanophyta (CYA), based on periphytons, were mostly constant throughout our study; (2) in terms of spatial variation, the CV values in the macroinvertebratebased metrics were lower than the CV values in the periphyton-based metrics, and these findings may be caused by the effects of changes in environmental factors; whereas, the CV values in the macroinvertebrate-based metrics were higher than those in the periphyton-based metrics, and these results may be linked to the influences of phenology and life history patterns of the macroinvertebrate individuals; and (3) the CV values for the functionalbased metrics were higher than those for the structuralbased metrics. Therefore, spatial and temporal variation for metrics should be considered when assessing applying the biometrics.

Higher reactivity of allochthonous vs. autochthonous DOC sources in a shallow lake

Dissolved organic carbon (DOC) reactivity in aquatic systems is essentially dependent on DOC precursor material and on the processes regulating its bioavailability, especially photodegradation and microbial activity. We investigated temporal changes (from hours to weeks) in the reactivity of allochthonous and autochthonous DOC sources in a macrophyte-dominated shallow lake using a set of incubation experiments. Changes in DOC fluorescence and absorbance properties due to biodegradation (BD) and to the combined effect of photo- and biodegradation (UV + BD) were traced. Allochthonous DOC was more reactive than autochthonous DOC (AutoDOC), showing higher DOC losses (between 22 and 36 %) and faster changes in DOC properties than AutoDOC. The effect of UV + BD was larger than BD alone for both sources of DOC. The rates of change of DOC properties were stronger during the first days of incubation and showed no regular pattern for any of the treatments or DOC sources. Our findings highlight the relevance of the timescale when assessing changes in DOC quality under different degradation pathways, as well as the need of discussing the labile character usually attributed to autochthonous DOC in systems dominated by submerged vegetation, as many shallow lakes or lagoons.

Impact of polychlorinated biphenyl and polycyclic aromatic hydrocarbon sequestration in sediment on bioaccumulation in aquatic food webs

It is not clear whether sequestration or aging of organic chemicals like polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) limits accumulation in higher levels of aquatic food chains. Therefore, the effect of aging on accumulation was studied in 1(-m3) model ecosystems that mimicked fish-dominated, macrophyte-dominated, and fish- and macrophyte-dominated shallow lakes. Also treatments without fish and macrophytes were included. General characteristics, biomasses, total (Soxhlet-extractable), and labile (6-h Tenax-extractable) PCB and PAH concentrations in sediment and biota were monitored over time. Accumulation data for PCB 28, PCB 149, and fluoranthene (native to the sediment taken from the field) were compared to those for spiked analogues PCB 29, PCB 155, and fluoranthene-d10. Labile fractions for spiked compounds were higher than for their native analogues and decreased over time, suggesting sequestration in the sediment. In the majority of cases, 6-h Tenax-extractable concentrations correlated better with concentrations in biota than Soxhlet-extractable concentrations. Ecosystem structure affected food web accumulation, but replicate variability was too high to detect clear treatment effects. Differences in accumulation between spiked compounds and their native analogues indicated an effect of aging for invertebrates, macrophytes, and benthivorous fish. Thus, aging may translate directly into reduced uptake at higher trophic levels.

A three-dimensional water quality-macrophyte interaction model for shallow lakes

A dynamic three-dimensional water quality model for macrophyte-dominated shallow lakes was proposed and tested. The proposed model is capable of simulating macrophytes and its interactions with water quality constituents such as dissolved oxygen (DO), organic nitrogen, ammonia, nitrate, organic phosphorus, orthophosphate, biochemical oxygen demand, phytoplankton and the sediment layer in shallow lakes. An existing two-dimensional hydrodynamic model has been utilized in conjunction with the water quality model to simulate water levels, velocities and flow rates. The modelled macrophyte processes are photosynthesis, respiration, mortality and excretion. Hourly simulation of photosynthesis process has been realized. The hourly simulations need special attention to predict diurnal variations of DO in macrophyte dominated lakes. The proposed water quality simulation model was subjected to calibration, verification and prediction processes using the data collected from Mogan Lake, Turkey. Mogan Lake exhibits wide variations of macrophyte biomass seasonally. The lake also exhibits highly variable DO levels both seasonally and diurnally. Statistical error quantification methods have been utilized to test the goodness of fit between the water quality model predictions and field measurements. Good agreement has been achieved between model predictions and measurements. Moreover, uncertainty analysis has been carried out for macrophyte and DO constituents. The analysis showed that the magnitude of the saturated growth rate of macrophyte is the most sensitive model parameter both for macrophyte and DO. The proposed water quality simulation model gave some promising initial results as a management tool to predict the expected reductions for the undesired consequences of eutrophication problem.