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Map of the Great Lakes of North America showing the location of the 62 wetlands sampled between 1995 and 1999.
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We collected water quality, land use, and aquatic macrophyte information from 62 coastal and inland wetlands in the Great Lakes basin and found that species richness and community structure of macrophytes were a function of geographic location and water quality. For inland wetlands, the primary source of water quality degradation was inputs of nutr...
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... and forested land in their wa- tersheds to ensure a sufficient gradient of disturbance (Crosbie and Chow-Fraser 1999). In addition, wetlands were chosen from a broad geographic range: from the St. Lawrence River just east of Cornwall, down to the Windsor-Detroit area and Lake St. Clair, and up to Lake Superior and the Ontario-Minnesota border (Fig. 1). Forty-six of these were coastal marshes (within 2 km of the Great Lakes shoreline but not separated hydrologically from the lake due to dams or waterfalls) of the upper (Huron, Superior) and lower (Ontario, Erie) lakes, while the remaining 16 wetlands were located inland within the Great Lakes -St. Lawrence River basin. All wetlands ...
Citations
... So why in the 2016 NWCA dataset do CHLA and TURB not track the nutrient increase that comes with increasing landscape disturbance, as evidenced by declining strength of correlation to TN and TP (Table 4) and lack of shifts in the CHLA and TURB distribution (Fig. 7)? Great Lakes coastal wetlands are the wetland type most studied for nutrient responses, and CHLA and TURB clearly do increase in concert with increased nutrients there (e.g., Crosbie and Chow-Fraser 1999;Gentine et al. 2022;Lougheed et al. 2001;Morrice et al. 2008). Cheruvelil et al. (2022) speak of the limited understanding of nutrient responses in very shallow lakes (maximum depth < 5m) and find the CHLA vs TP relationship to be less steep in shallow than non-shallow lakes, confirming our finding in wetlands of even more muted response of CHLA to nutrients. ...
Anthropogenic impacts on lake and stream water quality are well established but have been much less studied in wetlands. Here we use data from the 2016 National Wetland Condition Assessment to characterize water quality and its relationship to anthropogenic pressure for inland wetlands across the conterminous USA. Water samples obtained from 525 inland wetlands spanned pH from < 4 to > 9 and 3 to 5 orders of magnitude in ionic strength (chloride, sulfate, conductivity), nutrients (total N and P), turbidity, planktonic chlorophyll, and dissolved organic carbon (DOC). Anthropogenic pressure levels were evaluated at two spatial scales – an adjacent scale scored from field checklists, and a catchment scale indicated by percent agricultural plus urban landcover. Pressure at the two spatial scales were uncorrelated and varied considerably across regions and wetland hydrogeomorphic types. Both adjacent- and catchment-scale pressure were associated with elevated ionic-strength metrics; chloride elevation was most evident in road-salt using states, and sulfate was strongly elevated in a few sites with coal mining nearby. Nutrients were elevated in association with catchment-scale pressure but concomitant changes were not seen in planktonic chlorophyll. Acidic pH and high DOC occurred primarily in upper Great Lakes and eastern seaboard sites having low anthropogenic pressure, suggesting natural organic acid sources. Ionic strength and nutrients increased with increasing catchment-scale pressure even in Flats and closed Depression and Lacustrine sites, which indicates connectivity to rather than isolation from upland anthropogenic landuse even for wetlands lacking inflowing streams.
... Studies in the Great Lakes region have shown a well-established relationship between watershed development and coastal wetland water quality (Uzarski et al., 2005;Danz et al., 2007;Kovalenko et al., 2018), plankton (Sierszen et al., 2012;Larson et al., 2016;Host et al., 2019), wetland vegetation (Lougheed et al., 2001;Frieswyk and Zedler 2007), aquatic invertebrates (Cooper et al., 2007;Depew et al., 2011), and fishes (Brazner 1997;Brazner andBeals 1997, Danz et al., 2007;Trebitz et al., 2009;Kovalenko et al., 2018). These studies largely agree that land use in the Great Lakes region influences water quality and biotic assemblages, with agriculture and development being linked to an overall decrease in habitat integrity metrics. ...
... In the UMR, the late phase of recovery (years 2015-2019, 15 years after the early phase) was characterized by the greatest macrophyte prevalence and relative stability (Figure 1b, and see Bouska et al., 2022;Drake et al., 2022;Larson, Lund, et al., 2022). Thus, we expected the early phase would have only a few turbid-tolerant and cosmopolitan species (Lougheed et al., 2001), such as Stuckenia pectinata (L.) Borner (POPE6), Potamogeton crispus L. (POCO3), Ceratophyllum demersum L. (CEDE4), and Elodea canadensis Michx. (ELCA7). ...
We used a 22-year dataset (n = 18,000 sampling plots) to identify
aquatic vegetation types during an “early phase” and “late phase” of plant
recovery at multiple spatial scales nested within a 500-km river reach of the
Upper Mississippi River, USA. Impounded areas upriver from dams had
matured five vegetation types: lotus (Nelumbo lutea Willd.), submersed (a mix
of 11 common submersed species), watercelery (Vallisneria americana
Michx.), arrowheads (Sagittaria rigida Pursh and Sagittaria latifolia Willd.),
and a diverse community (with high diversity indices and multiple life forms).
The vegetation types were associated with three environmental gradients
related to inundation depth and duration, system productivity, and water clarity.
These five vegetation types are known to be of high ecological value to fish
and wildlife and thus targets for restoration.
... Not surprisingly, water quality degradation and SAV abundance are negatively correlated (Lougheed et al. 2001;Trebitz et al. 2009a, b;Giacomazzo et al. 2020). The most important cause of SAV loss is the degradation of the water-column light environment, due to both sedimentary turbidity and phytoplankton growth, the latter being enhanced by nutrient-induced eutrophication processes (Sand-Jensen and Borum 1991;Scheffer et al. 1993;Hidding et al. 2016). ...
Many freshwater ecosystems worldwide are threatened by increasing water turbidity and extensive submerged aquatic vegetation (SAV) loss, with potential consequences on aquatic communities. Such changes in water quality and habitat features affect the relative abundance of species in the community and/or the composition of ecological guilds altering the trophic network. Here, we estimated the relationship between fish species and both SAV abundance and water quality in Lake St. Pierre (Québec, Canada), a shallow fluvial lake of the St. Lawrence River. To explain the association between the fish community and environmental variables, we performed multiple linear regressions on fish abundance, species richness, and Shannon diversity calculated at 133 stations, along a gradient of turbidity, temperature, and SAV abundance. In addition, we estimated the relationship between dominant fish species abundance and environmental variables by using canonical correspondence analysis (CCA). Species richness and abundance were positively related to SAV. Turbidity was negatively related to fish abundance, but had an unexpected positive effect on diversity (Shannon and species richness). By quantifying the association between fish species and habitat features, this study contributes to a better understanding of mechanisms structuring fish communities in changing environments.
... Despite their importance, Great Lakes coastal wetlands (GLCWs) face many challenges from anthro-pogenic activities, as over 50% of GLCW area has been lost to filling, dredging, and diking, and remaining wetlands continue to be at risk of degradation (Maynard and Wilcox, 1997). Anthropogenic activities have been associated with increased concentrations of contaminants and altered water chemistry (Danz et al., 2007;Morrice et al., 2008;Robertson and Saad, 2011), along with changes in fish (Danz et al., 2007;Schock et al., 2014), macroinvertebrate (Schock et al., 2014), bird (Danz et al., 2007), and macrophyte communities (Johnston et al., 2009;Lougheed et al., 2001). ...
... For example, Johnston and Brown, (2013) reported that water quality in two floristically distinct Typha communities were chemically distinct in several variables including chlorophyll-a. Additionally, Lougheed et al., (2001) found that variation in SAV communities could be explained by levels of disturbance, and that Pontederia is intolerant of degraded conditions while Sagittaria is tolerant of degradation. Our dataset included single categories for Typha, SAV, and Peltandra/Sagittaria/Ponte deria, which may dampen the signal of vegetation types in our study and make it more difficult to distinguish an effect of vegetation type on phytoplankton biomass. ...
Coastal wetlands of the Laurentian Great Lakes are diverse and productive ecosystems that provide many ecosystem services, but are threatened by anthropogenic factors, including nutrient input, land-use change, invasive species, and climate change. In this study, we examined one component of wetland ecosystem structure – phytoplankton biomass – using the proxy metric of water column chlorophyll-a measured in 514 coastal wetlands across all five Great Lakes as part of the Great Lakes Coastal Wetland Monitoring Program. Mean chlorophyll-a concentrations increased from north-to-south from Lake Superior to Lake Erie, but concentrations varied among sites within lakes. To predict chlorophyll-a concentrations, we developed two random forest models for each lake – one using variables that may directly relate to phytoplankton biomass (“proximate” variables; e.g., dissolved nutrients, temperature, pH) and another using variables with potentially indirect effects on phytoplankton growth (“distal” variables; e.g., land use, fetch). Proximate and distal variable models explained 16–43% and 19–48% of variation in chlorophyll-a, respectively, with models developed for lakes Erie and Michigan having the highest amount of explanatory power and models developed for lakes Ontario, Superior, and Huron having the lowest. Land-use variables were important distal predictors of chlorophyll-a concentrations across all lakes. We found multiple proximate predictors of chlorophyll-a, but there was little consistency among lakes, suggesting that, while chlorophyll-a may be broadly influenced by distal factors such as land use, individual lakes and wetlands have unique characteristics that affect chlorophyll-a concentrations. Our results highlight the importance of responsible land-use planning and watershed-level management for protecting coastal wetlands.
... Although our analysis is the first to examine the macrophyte growth form distribution in relation to nutrients at this large scale, others have observed similar patterns at local scales. For example, Alahuhta et al. (2014) and Lougheed et al. (2001) found that nearshore emergent species were indicative of turbid nutrient-rich waters, while Lougheed et al. (2001) found that a high density of submerged forms indicated higher wetland quality. Likewise, Chambers (1987) found a shift from meadow-forming growth forms (such as rosettes) at sites with low nutrient input to canopy-forming (i.e., caulescent) forms at sites with higher nutrient input. ...
... Although our analysis is the first to examine the macrophyte growth form distribution in relation to nutrients at this large scale, others have observed similar patterns at local scales. For example, Alahuhta et al. (2014) and Lougheed et al. (2001) found that nearshore emergent species were indicative of turbid nutrient-rich waters, while Lougheed et al. (2001) found that a high density of submerged forms indicated higher wetland quality. Likewise, Chambers (1987) found a shift from meadow-forming growth forms (such as rosettes) at sites with low nutrient input to canopy-forming (i.e., caulescent) forms at sites with higher nutrient input. ...
Premise:
Aquatic macrophyte species abundance and nutrient affinity are used in metrics to assess the trophic condition of lakes and rivers. The development of these indices is often regional, with inter-regional comparisons being complicated by the lack of taxonomic overlap. Here, we use a traits-based approach to expand the geographic scope of existing metrics.
Methods:
We generalized European trophic affinity values using the response of plant growth form to the light-nutrient gradient, then applied these values to sites in Canada. We evaluated the method's performance against the measured total phosphorus concentration (TP).
Results:
Free-floating and emergent growth forms were associated with enriched waters (>0.2 mg/L TP), whereas rosette forms were associated with oligotrophic conditions (<0.05 mg/L TP). The responses were longitudinally consistent, and the site scores among indices were highly collinear. Growth form-based scores were more strongly correlated with TP than were species-based scores (0.42-0.56 versus 0.008-0.25).
Discussion:
We leveraged the ecological relationship between increased surface water nutrient enrichment and the dominance of particular aquatic plant growth forms to generalize aquatic plant trophic indices. We demonstrated an approach for adapting species-based indices to plant traits to facilitate a broader geographic application and simpler data collection, which could be used to develop an easily applied trait-based method of assessing water nutrient status.
... Despite their importance, Great Lakes coastal wetlands (GLCWs) face many challenges from anthro-pogenic activities, as over 50% of GLCW area has been lost to filling, dredging, and diking, and remaining wetlands continue to be at risk of degradation (Maynard and Wilcox, 1997). Anthropogenic activities have been associated with increased concentrations of contaminants and altered water chemistry (Danz et al., 2007;Morrice et al., 2008;Robertson and Saad, 2011), along with changes in fish (Danz et al., 2007;Schock et al., 2014), macroinvertebrate (Schock et al., 2014), bird (Danz et al., 2007), and macrophyte communities (Johnston et al., 2009;Lougheed et al., 2001). ...
... For example, Johnston and Brown, (2013) reported that water quality in two floristically distinct Typha communities were chemically distinct in several variables including chlorophyll-a. Additionally, Lougheed et al., (2001) found that variation in SAV communities could be explained by levels of disturbance, and that Pontederia is intolerant of degraded conditions while Sagittaria is tolerant of degradation. Our dataset included single categories for Typha, SAV, and Peltandra/Sagittaria/Ponte deria, which may dampen the signal of vegetation types in our study and make it more difficult to distinguish an effect of vegetation type on phytoplankton biomass. ...
... High total macrophyte abundance was recorded in October 2018, while low total macrophyte abundance was recorded in March 2019. Phosphorus and nitrogen are known to stimulate macrophytes' growth (Dar et al., 2015;Lougheed et al., 2001;Rosset et al., 2010). The variation of macrophyte growth across the month indicated the influence of phosphorus and nitrogen in the lake. ...
Nutrient input from internal and external sources could regulate the variability and abundance of algal and macrophytes in freshwater lakes. This study explores the response of algal and macrophyte growth in relation to internal and external nutrient loading. This study was conducted over a 12-month period in a eutrophic shallow urban lake known as Slim River Lake, which located in Perak state, Malaysia. The internal nutrient loading was calculated during five identified dry periods. Meanwhile, external nutrient loading was measured from stormwater runoff after storm events. Algal biomass was measured twice a month, while total macrophyte abundance was measured once in a month. In this lake, internal nutrient loading could contribute up to 7538.33 kg total phosphorus and 42.23 kg total nitrogen during dry periods. Meanwhile, external nutrient loading quantified from the stormwater runoff contributed up to 401,500 kg total phosphorus and 4611.67 kg total nitrogen. The highest monthly mean for algal biomass and total macrophyte abundance was recorded as 60,343.75 cells/mL and 821.50, respectively. Based on the Pearson correlation analysis, algal biomass was significantly correlated with the internal total phosphorus loading (r = 0.54, p < 0.05). In addition, algal biomass also shows an inverse relationship with the external total phosphorus loading (r = − 0.44, p < 0.05). In contrast, total macrophyte abundance was significantly correlated with the external total phosphorus loading (r = 0.50, p < 0.05) and external total nitrogen loading (r = 0.44, p < 0.05). These results suggest that variation of nutrient sources triggers a different response by algal and macrophytes in the study lake. In implications, these findings show that a combination approach in reducing nutrients from sediment and anthropogenic sources is required for potential lake restoration.
... Invasive aquatic macrophytes often are recorded to be ecologically and economically damaging, for example, through increased flood risk, devaluation of property, the disruption of navigation, water abstraction, irrigation and recreational activities (Hussner et al., 2017;Oreska & Aldridge, 2011). Studies typically have focused on a small number of variables to explain invasion success, including the relationships between macrophytes and spatiotemporal patterns in water quality and the surrounding land use (Lougheed et al., 2001;Sass et al., 2010). A more comprehensive understanding of invasion drivers, including the emergent effects of other species impacts and their abiotic interactions, is needed to enhance predictive capacities for future invasions. ...
Biological invasions, especially invasive alien aquatic plants, are a major and growing ecological and socioeconomic problem worldwide. Freshwater systems are particularly vulnerable to invasion, where impacts of invasive alien species can damage ecological structure and function. Identifying abiotic and biotic factors that mediate successful invasions is a management priority. Our aim was to determine the environmental correlates of Elodea nuttallii ; a globally significant invasive aquatic species.
Elodea nuttallii presence/absence (occurrence), extent (patch area) and percentage cover (density) was visually assessed from a boat throughout Lough Erne (approximately 144 km ² ), County Fermanagh, Northern Ireland during the active summer growth season (July–September). In addition, substrate type and zebra mussel Dreissena polymorpha occurrence was recorded. Fourteen water chemistry variables were collected monthly from 12 recording stations throughout the lake during the 9 years before the survey to spatially interpolate values and establish temporal trajectories in their change. Shoreline land use was derived from CORINE land cover maps. Environmental associations between E. nuttallii , substrate, D. polymorpha , water chemistry and land use were assessed.
Elodea nuttallii occurrence was positively associated with water conductivity, alkalinity, suspended solids, phosphorus (both total and soluble) and chlorophyll‐ a concentrations, but negatively associated with pH and total oxidised nitrogen. E. nuttallii patch extent and proportional cover were positively associated, to varying degrees, with the presence of D. polymorpha , biological oxygen demand, water clarity and soft substrate, but negatively associated with urban development and ammonium.
Elodea nuttallii displayed high levels of phenotypic plasticity in response to environmental variation, allowing it to adapt to a wide range of conditions and potentially gain competitive advantage over native or other invasive macrophytes.
It is evident that multiple abiotic and biotic factors, including facilitation by co‐occurring invasive dreissenid mussels, interact to influence the distribution and abundance of E. nuttallii . Thus, it is necessary to consider a more comprehensive environmental context when planning Elodea management strategies.
... Agricultural and urban land use in wetland catchments of the Great Lakes has been shown to affect nutrient enrichment, water clarity, and sediment quality (Crosbie and Chow-Fraser 1999;Trebitz et al. 2007;Morrice et al. 2008;Robertson and Saad 2011;Harrison et al. 2020). In a basin-wide study, Lougheed et al. (2001) concluded that the proportion of agricultural and urban land in wetland watersheds was a statistically significant predictor of water quality. ...
Loss of Great Lakes wetlands due to changes in land use, hydrology, nutrient inputs, and invasive species led to the need for studies involving physical factors that influence growth of invasive cattails (Typha). Thus, in 18 Lake Ontario coastal wetlands, we sampled vegetation along stratified random transects and collected water samples for total phosphorus (TP) analyses. We used GIS to determine watershed area, percent land use as croplands, and length of lotic surface waters entering wetlands. A greenhouse growth experiment with a full factorial random block design was used to investigate the effects of variable hydroperiod and phosphorus concentrations on T. × glauca biomass changes. Correlation analyses of wetland data revealed that TP in field studies was related to percent croplands but not lotic length; mean percent Typha was not related to TP. In the growth experiment, above- and below-ground biomass increased significantly for simple main effects of hydroperiod and phosphorus concentrations. Multiple pairwise interaction comparisons between hydrology and nutrient treatments showed that effects of phosphorus concentration were present only at longer hydroperiods. Lack of correlation between Typha and phosphorus concentrations in the field was likely due to the overwhelming effect of water-level regulation on Lake Ontario. The greenhouse study demonstrated that increasing concentrations of phosphorus positively influenced cattail growth in a controlled setting. Although phosphorus positively influenced growth, hydrologic regime had the greatest influence on cattail growth, with increased biomass as hydroperiod increased. More natural hydrology and management of phosphorus inputs may help limit spread of Typha.