Occurrence Of Aquatic Macrophytes Research Articles

Growth forms and life-history strategies predict the occurrence of aquatic macrophytes in relation to environmental factors in a shallow peat lake complex

Aquatic ecosystems provide vital services, and macrophytes play a critical role in their functioning. Conceptual models indicate that in shallow lakes, plants with different growth strategies are expected to inhabit contrasting habitats. For shallow peat lakes, characterized by incohesive sediments, roles of growth forms, life-history strategies and environmental factors in determining the occurrence of aquatic vegetation remain unknown. In a field survey, we sampled 64 points in a peat lake complex and related macrophyte occurrence to growth forms (floating-leaved rooted and submerged), life-history strategies for overwintering (turions, seeds, rhizomes) and environmental factors (water depth, fetch, and porewater nutrients). Our survey showed that macrophyte occurrence relates to water depth, wind-fetch, and nutrients, and depends on growth form and life-history strategies. Specifically, rooted floating-leaved macrophytes occur at lower wind-fetch/shallower waters. Submerged macrophytes occur from low to greater wind-fetch/water depth, depending on life-history strategies; macrophytes with rhizomes occur at greater wind-fetch/depth relative to species that overwinter with seeds or turions. We conclude that growth form and life-history strategies for overwintering predict macrophytes occurrence regarding environmental factors in peat lakes. Therefore, we propose an adapted model for macrophyte occurrence for such lakes. Altogether, these results may aid in species-selection to revegetate peat lakes depending on its environment.

Effect of shipping induced changes in flow velocity on aquatic macrophytes in intensively navigated rivers

In the last decades, the aquatic vegetation of the river Rhine has declined. In order to rehabilitate the vegetation in the river it is vital to gain insights in the environmental factors that affect the occurrence and establishment of aquatic macrophytes. Especially navigation is expected to negatively influence the environmental conditions through generating water displacements that changes flow velocities in the littoral zones. The aim of this study was to assess the effect of navigation on occurrence of aquatic macrophytes species in the river Rhine by 1) deriving a comprehensive overview of their sensitivities to flow velocity with the use of species sensitivity distributions (SSDs), and 2) calculating the potentially not occurring fraction (PNOF) of their species pool based on measurements of flow velocities during ship passages at various types of littoral zones. Maximum flow velocity sensitivity ranged from 43 to 120 cm sö1. Field measured flow velocities fluctuated mostly between 0 and 10 cm sö1. However, maximum measured flow velocities during ship passages ranged between 45 and 74 cm. sö1. This resulted in a PNOF value of almost 0.50, indicating that 50% of the plant species is potentially absent due to ship generated changes in flow velocities. As shipping intensity is expected to increase in the future the likelihood of flow velocities limiting macrophytes is expected to increase. This highlights the need of constructing connected backwaters, side channels and shore channels behind longitudinal training dams as they decrease the influence of navigation on flow velocity.

Morphological and physiological traits of aquatic macrophytes respond to water chemistry in the Amazon Basin: an example of the genus Montrichardia Crueg (Araceae)

Species composition and occurrence of aquatic macrophytes in the Amazon Basin are associated with the hydrology and geomorphology of the catchment area. Nonetheless, the distribution of the Neotropical genus Montrichardia in the Amazon floodplains remains unclear. Three taxa of the genus were described: Montrichardia linifera (Arr.) Schott (ML), associated with nutrient-rich rivers; Montrichardia arborescens (L.) Schott (MA) and M. arborescens var. aculeata (G. Mey.) Engl., growing in nutrient-poor rivers. We hypothesize that different taxa can be discriminated according to variation in density, morphology, physiology, and biomass along environmental gradients of water characteristics and soil fertility. Samples of 55 populations of Montrichardia were taken in rivers with contrasting water types in the Amazon Basin along a gradient of declining soil fertility from Western to Eastern Amazonia spanning about 2,500 km. Local phenotypic variations and discriminant analysis separated ML and MA with MA as subset of MA. Water chemistry influenced the distribution of taxa. The nutritional soil gradient at the basin level clearly explained the distribution of ML, but not that of MA. The distribution pattern of ML was similar to that of tree species in the Amazon Basin, with higher density in West Amazon.

Predicting aquatic macrophyte occurrence in soft-water oligotrophic lakes (Pyrenees mountain range)

Distribution of aquatic macrophytes in lakes is related to geographical, morphological, catchment and water chemistry variables as well as human impacts, which modify the original environment. Here, we aim at building statistical models to establish the ecological niches of 11 aquatic macrophytes (10 different phanerogams and the genus Nitella ) from oligotrophic soft-water lakes and infer their ecological requirements and environmental constraints at the southernmost limit of their distribution. Macrophyte occurrence and environmental variables were obtained from 86 non-exploited oligotrophic soft-water lakes from the Pyrenees (Southern Europe; 42o50´N, 1o00´E); macrophytes inhabited 55 of these lakes. Optimum ranges and macrophyte occurrence were predicted in relation to 18 geographical, morphological, catchment and water chemistry variables using univariate and multivariate logistic models. Lakes at low altitude, in vegetated catchments and with low water concentration of NO 3 - and SO 4 -2 , were the most suitable to host macrophytes. In general, individual species of aquatic macrophytes showed clear patterns of segregation along conductivity and pH gradients, although the specific combination of variables selected in the best models explaining their occurrence differed among species. Based on the species response to pH and conductivity, we found Isoetes lacustris have its optimum in waters with low conductivity and pH (i.e. negative monotonic response). In contrast, Callitriche palustris , Ranunculus aquatilis , Subularia aquatica , Nitella spp., and Myriophyllum alterniflorum showed an optimum at intermediate values ( i.e. unimodal response), whereas Potamogeton berchtoldii , Potamogeton alpinus , and Ranunculus trichophyllus as species had their optimum at relatively high water pH and conductivity (i.e. positive monotonic response). This pattern has been observed in other regions for the same species, although with different optima and tolerance ranges. The parsimonious models developed here allowed us to explore niche requirements for each species and to predict the occurrence of macrophytes and of individual species in any particular lake by using only few, easily measured environmental variables. This is of interest to forecast possible changes related to global change and to assist managers in making conservation, management and restoration decisions.

Environmental factors explaining the distribution and diversity of vascular aquatic macrophytes in a highly heterogeneous Mediterranean region

The study of the relationships between vascular aquatic macrophyte occurrence, species richness and the local environment are central for suitable ecosystem quality assessments, freshwater bodies management and assistance for macrophyte restoration. Here we quantify the importance of the local factors, both water column and sediment, to provide tools for lentic water systems management and conservation in a Mediterranean region. We surveyed 90 water bodies along a 2500m altitudinal gradient in Catalonia (NE Spain). Despite its relatively small scale, the area of study exhibits large-scale environmental gradients mainly related to a diverse geology and climate. In consequence, the response of aquatic macrophytes to a broad range of environmental conditions can be studied without interference of biogeographical clines. We identified all vascular aquatic macrophytes and analyzed 35 environmental variables at each site. Local environmental factors accounted for only 19% of variance in aquatic macrophyte distribution. Even though water column variables explained more variance than sediment variables in a variance partitioning analysis (pCCA), a mixed model integrating variables of both compartments performed better. The most important variables driving aquatic macrophyte distribution were water conductivity, water DOC, water K, water pH, water Na, sediment organic matter, sediment Na and water nitrate. CCA between species and water and sediment variables clearly segregated coastal lagoons, temporary pools and alpine lakes over two main gradients: ionic content and water body productivity. Species richness was low (4.2 species per water body on average) and GAM showed weak correlations with sediment and most water column variables. The best factor explaining species richness was the geomorphological typology, but only temporary pools were significantly different from the other types and had the highest species richness. Thus, temporary pools were unique and displayed a high biodiversity, strengthening the need for their preservation.

Temporal and spatial variation of limnological variables and biomass of different macrophyte species in a Neotropical reservoir (São Paulo - Brazil)

AIM: This study reports an investigation of limnological characteristics and aquatic macrophyte occurrence in a neotropical reservoir in order to assess the spatio-temporal variation of water and sediment variables and their influence on plant distribution. METHODS: Macrophytes, water and sediment samples were collected from a Brazilian reservoir in different seasons from four main arms of the reservoir. In total sixteen water-sediment variables were analyzed including N:P ratio and Trophic State Index. The plants were collected using a quadrat sampling procedure and the dry weight per sample was measured. MANOVA was performed to evaluate spatial and temporal variation of environmental variables as well as seasonal biomass differences. To assess the relationship among environmental variables and macrophytes an ordination analysis (using Canonical Correspondence Analysis: CCA) was carried out. RESULTS: The spatial and temporal variation of limnological variables generated a heterogeneous system which supports the presence of different species of macrophyte. pH, dissolved oxygen and sediment composition were important predictors of Polygonum lapathifolium occurrence while nutrients were associated with Eichhornia crassipes and Pistia stratiotes. Inorganic substances were related to biomass variation of Eichhornia azurea and Myriophyllum aquaticum. CONCLUSIONS: The spatial variation of the environmental variables has caused heterogeneity in the reservoir and it may support the occurrence of different species of macrophyte. Limnological variables highlighted in CCA are important to predict the species occurrence and their control in the study area.

Large channel confluences influence geomorphic heterogeneity of a southeastern United States river

Detection of biological patterns in structurally complex rivers is difficult but essential in the management of imperiled species. On the basis of the network dynamics hypothesis (NDH), we predicted that tributaries exert a strong influence on main stem morphology, mediated by tributary sediment inputs. We predicted that the likelihood that a tributary will affect main stem geomorphology depends on the ratio of the tributary basin area to the main stem basin area (TBA:MBA). Although the results of this study do not indicate that TBA:MBA is a useful predictor of the presence of shallow alluvium‐dominated confluences (i.e., shoals) in the Etowah River, in Georgia, alluvial shoals were closer to tributary mouths than were other shoal types, indicating an association with tributaries. Shoals near large tributary confluences also contained a larger proportion of gravel and cobble bed sediments and were wider than adjacent, downstream shoals. These confluence‐associated shoals may be ecologically different in that aquatic macrophyte occurrence is higher in wide shoals with coarse sediments, and several state and federally listed darters (Percidae) are associated with shoals and these aquatic macrophytes. Recognizing confluence‐associated shoals as unique shoal types may aid researchers in understanding the distribution patterns of these aquatic organisms.

Occurrence of Aquatic Macrophytes in a Eutrophic Subtropical Lake in Relation to Toxic Wastewater and Fish Overstocking

ABSTRACT We studied nutrient level and macrophytes in three different naturally separated basins of Lake Liangzi, a large subtropical shallow lake subjected to different loadings of nutrients, toxic wastewater, and fish/crab farming. The biomass of macrophytes decreased rapidly two years after the toxic wastewater entered the lake. Values of total phosphorus (TP), total nitrogen (TN) and chlorophyll a were significantly higher, while Secchi depth, pH, and dissolved oxygen were significantly lower in the toxic area than in the overstocked area and the area subjected to nutrient loading only. This study shows that lake management changes can induce a shift from a vegetation-dominated to a phytoplankton-dominated system. Our analysis suggests that TN rather than TP may be the limiting nutrient in this and other lakes in the middle to lower reaches of the Yangtze River.

An application of canonical correspondence analysis for developing ecological quality assessment metrics for river macrophytes

Summary1. Aquatic macrophyte composition and abundance is required by the European Union's Water Framework Directive for determining ecological status. Five metrics were produced that can be combined to determine the deviation of aquatic macrophytes from reference conditions in Northern Ireland's rivers.2. Species optima and niche breadths along silt, nitrate, pH, conductivity and dissolved oxygen gradients were generated from aquatic macrophyte and water quality surveys conducted at 273 sites throughout Northern Ireland using Canonical Correspondence Analysis (CCA). Five metric scores based on these environmental gradients were determined at new monitoring sites using the mean optima of the species occurring at the site, weighted by percentage cover and niche breadth of each species.3. A preliminary reference network of 32 sites of high physico‐chemical and hydromorphological quality, and representative of the range of river types in Northern Ireland, enabled reference metric scores to be produced for each river type. Five unimpacted and twenty impacted sites were used for testing the performance of the metrics. By subtracting reference metric scores from metric scores at a monitoring site measures of ecological impact could be determined along five different impact gradients. Metrics were also combined to give a measure of total ecological change.4. The metrics system distinguished unimpacted from impacted sites and correctly identified 77% of the known impacts. The metrics distinguished different types of impact, e.g. silt and nitrate.5. Aquatic macrophyte occurrence and abundance has high natural variability at a site, both temporally and spatially. This method was designed to be sensitive to ecological change whilst reducing noise caused by natural variation.

Species–environmental relationships of aquatic macrophytes in Northern Ireland

A data-set from 574 lakes in Northern Ireland was used to analyse the individual relationships of the occurrence of aquatic macrophytes to the lake environment. The 32 most frequent species were used in the analyses. The 21 environmental parameters recorded for each lake were divided into five groups; (1) geographical features; (2) lake physical variables; (3) lake-water chemistry summary variables; (4) lake-water major ions; and (5) lake-water nutrients. The species–environmental relationships were analysed using generalised additive models (GAM) and canonical correspondence analysis (CCA). The results were interpreted in terms of expected range, tolerance, and optimum of each species. Predictive models were made for each of the most frequent aquatic macrophytes along individual environmental gradients. The most influential variables are related to local-scale chemical and nutrient composition, both of which are highly correlated with altitude because hardwater, nutrient-rich lakes are restricted to the lowlands. Major ions and nutrients constrain the species into two groups associated with either low or high ionic concentration. The high ionic concentration group of species may be further divided into those associated with calcareous lakes or lakes with high sodium and chloride. Local-scale variation in lake chemistry and the strong environmental responses of the aquatic macrophytes suggest a strong local influence on species composition of different lakes, leading to the interpretation that the occurrence of a species in a lake is predominantly controlled by the catchment use, particularly farming and fertiliser use.

Species diversity and distribution of aquatic macrophytes in the Northern Quark, Baltic Sea

The occurrence of aquatic macrophytes was studied in a northern transition area of the Baltic Sea; the Northern Quark, Gulf of Bothnia. In the area there is a gradual, marked change in environmental conditions, the most prominent of which is a decrease in salinity from 5.0% in the Bothnian Sea to 3.5% in the Bothnian Bay. In all, 40 species of macrophytes were observed; 10 fucophyceans, 10 bangiophyceans, 8 chlorophyceans, 3 charophyceans, 1 tribophycean, 1 nostocophycean, 6 phanerogams and 1 water moss. 26 of the observed species were of marine and 14 of lacustrine origin. There was a clear change in species composition and community structure from south to north over the area. The vegetation at the southernmost localities had a marine character, with belt‐forming Fucus vesiculosus and a comparatively diverse flora of macroalgae. Further north, an ephemeral, lacustrine vegetation dominated by benthic diatoms and Cladophora aegagropila prevailed. The ratio marine: lacustrine species decreased from 4.2 to 1 when comparing a southern and a northern sub‐area of the Northern Quark. The species observed include 57 % of the marine macrophytes noted in the Aland and Archipelago Seas (N Baltic Proper) during the past two decades. Two marine species, Aglaothamnion roseum and Ahnfeltia plicata, are reported for the first time from the Northern Quark. This comprises a northern extension of their distribution limit with approximately 300 km.

Recent non-marine Ostracoda from Jamaica, West Indies

Abstract. Ostracods were sampled qualitatively at 22 sites from 15 waterbodies in the western part of Jamaica and determinations of the water chemistry and habitat characteristics were made at each locality. Most of the ostracods found belong to the Cypridinae, Cypridopsinae, Cyclocypridinae and Darwinulidae. There is a clear distinction between the faunas found in the larger, permanent lakes and the smaller ponds. The latter are subject to large fluctuations in volume and may desiccate either seasonally or interannually. Within the largest lake, Wallywash Great Pond, there is some degree of spatial zonation in the ostracod faunas that appears to be related to water depth and aquatic macrophyte occurrence. The distribution of modern ostracods within Wallywash Great Pond suggests that the late Quaternary faunal sequence from this lake is primarily a function of lake-level changes.

Declines in aquatic vegetation in navigation pool no. 8, upper Mississippi River between 1975 and 1991

AbstractThe biomass and frequency of occurrence of aquatic macrophytes observed during 1975 and 1991 in Navigation Pool No. 8 of the upper Mississippi River were compared. Samples were collected from contiguous backwater, isolated backwater and impounded habitat types. Overall declines were observed in both frequency and biomass between the two years. Changes in depth, water clarity and bed sediment texture were also observed. About 50% of the samples collected in 1991 had no vegetation, compared with 20% in 1975. The greatest reduction in frequency occurred among submergent taxa (77% in 1975 to 31% in 1991), whereas only slight declines were observed for emergent taxa. However, the mean biomass of both lifeforms decreased substantially (48 to 1 g/m2 for submergent and 61 to 27 g/m2 for emergent lifeforms). The mean total biomass declined from 114g/m2 in 1975 to 35 g/m2 in 1991. Declines were most evident in the impounded habitat, where the frequency of occurrence of submergent taxa decreased from 83% in 1975 to 11% in 1991, and mean biomass decreased from 90 to 1 g/m2. Similar but less extensive reductions in frequency and biomass of submergent taxa were observed in the contiguous backwater habitat. In contrast, both the frequency and biomass of floating‐leaved macrophytes increased slightly in contiguous backwater habitats. Changes in frequency and biomass of macrophytes in isolated backwater habitats were neligible between 1975 and 1991. It is hypothesized that changes in the macrophyte community structure may be related to physical changes associated with 57 years of impoundment.

東海地方のため池でみられる水生植物の種組成と水質との関係

To clarify the relationship between the occurrence of aquatic macrophytes and the chemical nature of the water, the flora of aquatic macrophytes grown in 122 irrigation reservoirs in Tokai District was investigated along with some major elements (pH and concentrations of Ca, K and Mg) in the water of 65 randomly selected reservoirs. By dividing the irrigation reservoirs into three altitudinal locations (plain, lower hillside and higher hillside), it was revealed that 23 species of the aquatic macrophytes (exclusive of two omnipresent species, Phragmites communis and Zizania latifolia) inhabiting these reservoirs could be classified into six groups. Since both pH and the concentrations of the three elements in the water gradually lowered with the higher altitude of reservoirs, it was supposed that the flora of each reservoir was considerably influenced by some elements of its water, and the latter must in turn have been affected by the geographical feature of the basin in which the reservoirs were located.