Coexistence of Lobelia dortmanna and Cladium mariscus, an ecological and paleobotanical study

Lobelia dortmanna L. (Lobeliaceae family) is an indicator species that is predominantly found in oligotrophic and acidic lakes. They are mainly distributed in northwestern Europe. Their occurrence in Poland is highly threatened by the increasing grade of human activity and environmental eutrophication; however, new sites of Lobelia were discovered in the last few decades, for example, in Lake Krzywce Wielkie situated in Bory Tucholskie National Park (BTNP), Poland. The existence of Lobelia in this lake was unexpected because Cladium mariscus was also found in the lake. Cladium has different ecological demands and is regarded as a species typical of calcareous habitats where calcium is found in abundance in the substrate. To explain the coexistence of both species in Krzywce Wielkie, pollen analysis of organic sediments was performed for four short cores collected from the littoral zone of the lake and for one long deep-water core. Additionally, macrofossil analysis was done for all the short cores. Pollen analysis revealed the existence of Cladium from the early Holocene period up to the present time. Pollen and seeds of Lobelia were found to be present since the beginning of the 20th century. Development of L. dortmanna and Myriophyllum alterniflorum populations and a decrease in the number of aquatic macrophytes in the eutrophic water indicate oligotrophication of water. This process started following the construction of drainage canal and the consequent water level decrease. This situation can be attributed to the abandonment of the agricultural areas adjoining the lake, which causes a decrease in the inflow of nutrients into the lake. Development of pine forest and establishment of BTNP enabled the protection and conservation of the surrounding catchment areas, thus restricting the potential eutrophication of the habitats.

Species diversity of macrophytes in Jagadishpur Reservoir, Kapilvastu District, Nepal

The present research was conducted for quantitative study and diversity analyses of aquatic macrophytes dwelling littoral zone of Jagadishpur reservoir, Kapilvastu district in three seasons, as winter (December), summer (April), and rainy (August). Altogether 58 species of macrophytes were recorded in study site, of which highest number of species (54) was occupied by angiosperms followed by three species of pteridophytes and one species of alga. These macrophytes varied in different morphological groups, viz., emergent, submerged, and rooted-floating leaf type. Maximum number of species were represented by emergents (39) followed by rooted-floating leaf type (12) and submerged (7) macrophytes. There was distinct seasonal variation in the distribution of macrophytes: based on importance value index, Nelumbo nucifera (IVI = 22.87), Scripus sp. (IVI = 28.01), Ipomoea carnea (IVI = 24.67) and Typha angustifolia (IVI = 29.01) were dominant in the winter; Nelumbo nucifera (IVI = 20.05), Cynodon dactylon (IVI = 20.07) and Ipomoea carnea (IVI = 21.17) were dominant in the summer and Nelumbo nucifera (IVI = 23.8) and Scripus sp. (IVI =25.56) were dominant in the rainy season. The highest species diversity (H’) of macrophytes was observed during summer (3.451), followed by rainy season (3.135) and winter (3.008). The luxuriant growth of aquatic macrophytes evidenced the highly productive nature of the lake, while the dominance of emergents among the growth forms indicates the encroachment of littoral vegetation, indicating a successional trend toward marsh meadow.

Anthropogenic Stressors in Upland Rivers: Aquatic Macrophyte Responses. A Case Study from Bulgaria

Upland rivers across Europe still exhibit undisturbed conditions and represent a treasure that we cannot afford to lose. We hypothesize that the combination of pristine and modified conditions could demonstrate biological responses along the stressor gradients. Thus, the response of aquatic macrophyte communities to anthropogenic stressors along upland rivers in Bulgaria was studied. Six stressors were selected out of 36 parameters grouped into hydromorphological, chemical variables and combined drivers (catchment land use). The stressors strongly affected species richness on the basis of biological type (bryophytes vs. vascular plants) and ecomorphological type (hydrophytes vs. helophytes). Hydrological alteration expressed by the change of the river’s base flow and altered riparian habitats has led to a suppression of bryophytes and a dominance of riverbank plant communities. Seventy-five percent of mountain sites were lacking bryophytes, and the vegetation at semi-mountainous sites was dominated by vascular plants. It can be concluded that hydropeaking, organic and inorganic pollution, and discontinuous urban structures caused important modifications in the aquatic macrophyte assemblages. Macrophyte abundance and the biological and ecomorphological type of aquatic macrophytes reflect multi-stressor effects in upland rivers.

Can turbid water and refuges with aquatic macrophytes increase the survival and growth of Brycon amazonicus larvae?

The productivity of aquatic organisms and higher concentration of suspended solids that occur in areas flooded by Whitewater Rivers and the presence of aquatic macrophytes are conducive to the initial development of matrinxã (Brycon amazonicus). The objective of this study was to evaluate whether turbid waters and refuges with aquatic macrophytes improve the survival and growth of the larvae of Brycon amazonicus, a species of great interest in Amazonian fish farming. For this, two experiments were conducted using a completely randomized design and with four replicas per treatment up to 120 hours after hatching (HAH), In experiment I: Brycon amazonicus larvae at 24 HAH were subjected to three treatments with different types of water: clear water (CW); clayey water (AW) and green water (GW). Experiment II: larvae with 24 HAH were maintained in clear water (CW); clear water with refuge (CWR); green water (GW); green water with refuge (GWR); clayey water (AW) and clayey water with refuge (AWR). Experiment I showed that clayey water, followed by green water, increased the survival of larvae (73.92 and 54.32%). Growth was best in larvae maintained in green water. In experiment II, the use of aquatic macrophytes did not influence the survival and growth of the larvae. Thus, we suggest the use of turbid (clayey and green) waters without refuge to increase the survival and growth of Brycon amazonicus larvae.

Chemical management strategies for starry stonewort : a mesocosm study

US Environmental Protection Agency (USEPA) approved algaecides and herbicides are frequently utilized to manage nuisance algae and aquatic macrophytes. However, there is limited information available on the effectiveness of these products for the management of starry stonewort. Thus, the goal of this research was to discern effective chemical control products for later growth stages of starry stonewort using mesocosm studies. Eleven treatments were evaluated using various combinations of four copper-based products, endothall, diquat, and carfentrazone – all with USEPA registrations for use in aquatic sites. To assess treatment efficacy, water quality, photophysiology, biomass changes, and bulbil viability were evaluated. Nine of the eleven treatments yielded lower dissolved oxygen concentrations and higher specific conductance when compared to the control. Photophysiological response varied by condition, but seven of eleven treatments resulted in significantly lower fluorescent and maximum fluorescent yield. Five of these also exhibited significantly lower average photosynthetic yields, with combination treatments resulting in more drastic decreases. Ten of the eleven treatments had significantly less biomass compared to the control when measured via wet weight; however, only four treatments were significant when measured via dry weight. Lastly, all conditions utilizing copper-based products significantly reduced bulbil viability while non-copper products had no impact.