We studied community–environment relationships of lake macrophytes at two metacommunity scales using data from 16 regions across the world. More specifically, we examined (a) whether the lake ...macrophyte communities respond similar to key local environmental factors, major climate variables and lake spatial locations in each of the regions (i.e., within-region approach) and (b) how well can explained variability in the community–environment relationships across multiple lake macrophyte metacommunities be accounted for by elevation range, spatial extent, latitude, longitude, and age of the oldest lake within each metacommunity (i.e., across-region approach). In the within-region approach, we employed partial redundancy analyses together with variation partitioning to investigate the relative importance of local variables, climate variables, and spatial location on lake macrophytes among the study regions. In the across-region approach, we used adjusted R² values of the variation partitioning to model the community–environment relationships across multiple metacommunities using linear regression and commonality analysis. We found that niche filtering related to local lake-level environmental conditions was the dominant force structuring macrophytes within metacommunities. However, our results also revealed that elevation range associated with climate (increasing temperature amplitude affecting macrophytes) and spatial location (likely due to dispersal limitation) was important for macrophytes based on the findings of the across-metacommunities analysis. These findings suggest that different determinants influence macrophyte metacommunities within different regions, thus showing context dependency. Moreover, our study emphasized that the use of a single metacommunity scale gives incomplete information on the environmental features explaining variation in macrophyte communities.
Documenting the patterns of biological diversity on Earth has always been a central challenge in macroecology and biogeography. However, for the diverse group of freshwater plants, such research ...program is still in its infancy. Here, we examined global variation in taxonomic, functional and phylogenetic beta diversity patterns of lake macrophytes using regional data from six continents. A data set of ca. 480 lake macrophyte community observations, together with climatic, geographical and environmental variables, was compiled across 16 regions worldwide. We (a) built the very first phylogeny comprising most freshwater plant lineages; (b) exploited a wide array of functional traits that are important to macrophyte autoecology or that relate to lake ecosystem functioning; (c) assessed if different large-scale beta diversity patterns show a clear latitudinal gradient from the equator to the poles using null models; and (d) employed evolutionary and regression models to first identify the degree to which the studied functional traits show a phylogenetic signal, and then to estimate community-environment relationships at multiple spatial scales. Our results supported the notion that ecological niches evolved independently of phylogeny in macrophyte lineages worldwide. We also showed that taxonomic and phylogenetic beta diversity followed the typical global trend with higher diversity in the tropics. In addition, we were able to confirm that species, multi-trait and lineage compositions were first and foremost structured by climatic conditions at relatively broad spatial scales. Perhaps more importantly, we showed that large-scale processes along latitudinal and elevational gradients have left a strong footprint in the current diversity patterns and community-environment relationships in lake macrophytes. Overall, our results stress the need for an integrative approach to macroecology, biogeography and conservation biology, combining multiple diversity facets at different spatial scales.
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•We are beginning to estimate global determinants of macrophyte diversity patterns.•We examine variation of taxonomic, functional and phylogenetic beta diversity.•Taxonomic and phylogenetic beta diversity is higher in the tropics.•Functional traits evolve independently of phylogeny in macrophytes worldwide.•Latitude and elevational gradients left a strong footprint in beta diversity.
Panfish support popular, socioeconomically valuable fisheries across the United States. Whereas Bluegill Lepomis macrochirus and Black Crappie Pomoxis nigromaculatus receive considerable research ...attention, Redear Sunfish L. microlophus are seldom studied despite their wide distribution, large size, socioeconomic contributions, and invasion potential in parts of their introduced range. We evaluated Redear Sunfish occurrence, density, relative abundance, growth, and size structure in 60 Florida lakes with varied surface area (2–12,412 ha), trophic state (oligotrophic to hypereutrophic), and macrophyte abundance (0.3–100% of lake volume inhabited), a range of environmental conditions over which Redear Sunfish populations have scarcely been investigated. Lake surface area, chlorophyll‐a concentration, and macrophyte abundance explained 98% of variation in Redear Sunfish occurrence. Redear Sunfish density increased asymptotically with calcium concentration, whereas relative abundance (electrofishing fish/h) peaked at intermediate surface area (50–100 ha) and chlorophyll a (20 μg/L). Mean length at age 3 declined with increasing macrophyte abundance and was parabolically related to Redear Sunfish density, peaking at approximately 450 fish/ha. The proportional size distribution (PSD) and PSD of preferred‐length fish were also negatively related to macrophyte abundance, and PSD declined with increasing Redear Sunfish density. Our results suggest that Redear Sunfish fisheries with abundant individuals of quality size (≥180 mm) require large (>100 ha), fertile (>20 μg/L chlorophyll a) lakes with calcium concentrations >5 mg/L, moderate macrophyte abundance (0–25% of lake volume inhabited), and Redear Sunfish densities between 200 and 700 fish/ha. Our modeling approach can help managers predict Redear Sunfish occurrence, density, relative abundance, growth, and size structure based on a suite of abiotic and biotic variables.
Hoyer MA, Canfield DE, Jr. 2022. A Limnological Yardstick based on phosphorus limitation. Lake Reserv Manage. 38:109-125.
A new tool called a Limnological Yardstick was developed using long-term (15 ...to 35 yr) lake chemistry data collected by volunteers of the Florida LAKEWATCH program. This yardstick can assist managers of aquatic systems with identifying where there is a great probability that phosphorus is not only the limiting nutrient, but the limiting environmental factor. When a lake's phosphorus-chlorophyll data lie below the yardstick's lower 95% confidence interval, phosphorus may be the limiting nutrient but not the limiting environmental factor, indicating where phosphorus control strategies will most likely fail. The Limnological Yardstick cannot directly identify the limiting environmental factor(s), as this requires a thorough limnological study of the lake because each lake has unique properties. Limiting environmental factors discussed are nitrogen, true color (Pt-Co units), nonalgal suspended solids, flushing rate, and aquatic macrophytes. The potential impacts of limiting environmental factors on the classification of lake trophic state and eutrophication are also discussed.
Hoyer, MV, Canfield, DE Jr. 2021. Volunteer-collected water quality data can be used for science and management. Lake Reserv Manage. 37:235-245.
This study addresses concerns that comparison studies ...between professional and volunteer-collected data have been of limited scope, conducted under experimental conditions, and that results may not be applicable to existing large-scale, long-term volunteer monitoring datasets. Historical (2008 to 2019) phosphorus, nitrogen, chlorophyll, and Secchi data collected by 5 Florida organizations charged with monitoring water quality were compared with Florida LAKEWATCH volunteer-collected data from 216 lakes. The state organizations had National Environmental Laboratory Accreditation Conference (NELAC)-certified laboratories and LAKEWATCH used modified procedures needed to accommodate a volunteer program. The lakes are located in central Florida, range in trophic status from oligotrophic to hypereutrophic, and provided approximately 650 independent overlapping annual geometric mean pairs for comparison. Paired t-tests comparing logarithmic transformed annual geometric mean data pooled from all professional organizations with similar overlapping volunteer-collected data showed significant (P < 0.05) differences for phosphorus, nitrogen, and Secchi depth but not for chlorophyll. The significant differences when reported arithmetically were only 1.1 µg/L, −1.1 µg/L, and 0.1 m, respectively. Regression analyses on the same data showed strong significant (P < 0.05) relations with coefficient of determinations (R
2
) of 0.91, 0.98, 0.79, and 0.78 for phosphorus, nitrogen, chlorophyll, and Secchi depth, respectively. Slopes for each paired regression were not significantly different from 1. These results demonstrate that volunteer-collected data were equivalent to data collected professionally, that the quality of volunteer data can be similar to that produced by NELAC-certified laboratories, and thus that data are adequate for both research and management.
Balloon angioplasty for recoarctation of the aorta is routinely performed in young children and is considered successful when the systolic gradient is reduced to < 10 mmHg. IMPACT defines acute ...procedural success solely based on a final gradient of < 10 mmHg and stratifies participating institutions based on these acute outcomes. Between February 2012 and December 2020, IMPACT data was analyzed for 110 coarctation interventions. Electronic medical records were reviewed, and primary endpoints were one of the following: (1) final analysis end date (June 2021), (2) patient death, or (3) most recent transcatheter or surgical reintervention. 64 (58.2%) interventions had a post-procedure CA gradient < 10 mmHg. Comparison of clinical patient outcome for acute success demonstrated no significant relationship using IMPACT (p = 0.70) criteria. There was no statistically significant difference between clinical success and failure for: pre- and post-treatment systolic gradients; absolute or percent change in systolic gradient; and pre-treatment aorta diameter. Clinical outcome and patient age did show a significant difference (p = 0.0093) with better clinical outcomes in older patients. Our analysis did not reveal a statistically significant difference between IMPACT criteria for successful treatment of CA and clinical outcome. These findings underscore a need to identify other clinical metrics that better predict outcome following CA balloon angioplasty treatment.
Summary
The performance of species richness estimators can be highly variable. Evaluating the accuracy and precision of different estimators for different assemblages is common in the ecological ...literature, but estimator performance is rarely measured in terms of research goals such as detecting patterns in diversity.
We evaluated the efficacy of nonparametric richness estimators to detect changes (i.e. type‐I and type‐II error rates) in species richness using two experimental designs: a block design and a trend analysis. We also evaluated estimator efficacy across a variety of species‐abundance distributions, species number and sample sizes. The evaluation was performed using simulated data that mimicked the qualities of real data to ensure real‐world relevance.
We found that the bias and precision of all estimators evaluated had high sensitivity to sample size and shifts in the species‐abundance distribution. Importantly, all estimators demonstrated elevated type‐I error rates when the species‐abundance distribution varied. These inflated type‐I error rates resulted in spurious conclusions about patterns in species richness.
Results suggest that caution should be taken when using nonparametric estimators to detect pattern in species richness. Furthermore, estimator evaluations should always include measures of type‐I and type‐II error rates. These quantities can reveal the inference consequences of the dependency of estimator bias and precision on community and sampling characteristics.
Atrial septal defect (ASD) closure is a common reason for referral to the cardiac catheterization laboratory. We report a case in which a relatively large Qp:Qs of 1.85:1 was demonstrated in the face ...of a small secundum ASD. This led to further investigation, ultimately leading to the discovery of an unusual atrial fistula. Rare cases of interatrial tunnels have been described in the literature, however, this is a unique case of a left atrial appendage to right atrial appendage fistula in the setting of a right juxtaposed left atrial appendage.
Research on Bluegills, Lepomis macrochirus R., is abundant but typically focuses on water bodies with similar environmental conditions. We assessed Bluegill density, relative abundance (catch per ...unit effort CPUE by electrofishing), growth, and size structure in 60 lakes with wide-ranging surface areas (2–12,412 ha), trophic states (oligotrophic–hypereutrophic), and macrophyte abundances (0.3–100 percent of lake volume inhabited PVI) across Florida, USA. Bluegill density and CPUE increased with lake productivity and decreased with macrophyte abundance. Bluegill growth increased with lake productivity and CPUE of stock-length Florida Bass, Micropterus floridanus L., a Bluegill predator. Bluegill size structure increased with lake productivity and decreased with Bluegill density. Results indicate that Bluegill fisheries with abundant individuals of quality size (≥150 mm) require productive (>25 μg/L chlorophyll-a concentration) lakes with moderate to high macrophyte coverage (PVI 50–100), abundant stock-length Florida Bass (>40 fish/h of electrofishing), and Bluegill densities <300 fish/ha. This study provides an approach to predict Bluegill population demographics based on abiotic and biotic factors, establish fisheries management expectations, and develop regional and lake-specific management tools.
Xiong C, Hoyer MV. Influence of land use and rainfall variability on nutrient concentrations in Florida lakes. Lake Reserv Manage. 35:25-37.
This research examined impacts of regional differences ...(total phosphorus zones TP Zones), land uses within watersheds (agriculture, urban, forest and wetland), and rainfall variability on nutrient concentrations (phosphorus and nitrogen) in Florida lakes (n = 87). Nutrient concentrations varied directly with TP Zones, which can be used as background nutrient concentrations within regions of Florida. After accounting for regional differences, lakes within watersheds with high percent agriculture tended to have higher nutrient concentrations, though relationships with nitrogen were strongest, suggesting different nutrient-transport mechanisms. Lakes within watersheds with high percent urban development showed no significant effect on nutrient concentrations, suggesting good nutrient management in urban areas. Lakes in watersheds dominated by forested land cover had low nitrogen concentration reflecting nutrient-buffering capabilities of forest stands. Lakes in watersheds with greater wetland coverage tended to have high nutrient concentrations, conflicting with previous studies and reflecting the complex nutrient-related processes that occur within wetlands. Cumulative rainfall deviations measured over a 20 yr period were significantly correlated (both positively and negatively) with nutrient concentrations within approximately 40% of the study lakes and the mechanisms driving these relations may overshadow impacts of land use within watersheds and changes in land use over time on lake nutrient concentrations. A thorough investigation of watershed land uses and relations between rainfall and limnological mechanisms must be considered before applying a nutrient management strategy to individual lakes.
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