Live under strong power: A third plant species alters interspecific interactions between two plant species

The scope and complexity of interactions within community food webs necessitates their simplification to a community module scale for conducting empirical studies. An outdoor mesocosm study in the USA quantified the strengths of direct and indirect interactions between two herbivore congeners that fed on two aquatic plant species while sharing a parasitoid. Kalopolynema ema (Hymenoptera: Mymaridae) is a stenophagous native egg parasitoid that attacks the hemipteran species in this study, Megamelus davisi (Hemiptera: Delphacidae), a native herbivore that feeds on the native aquatic species Nuphar advena, and the introduced biological control agent Megamelus scutellaris (Hemiptera: Delphacidae) that feeds on the non‐native aquatic species waterhyacinth, Pontederia crassipes. The presence of M. scutellaris did not significantly increase parasitism of M. davisi indicating that apparent competition was not a factor in this community module. There was no evidence of any trophic cascades caused by these interactions based on the relative growth rates of biomass and leaf area for both plant species. Synthesis and applications. The relative strengths of community interactions varied with herbivore densities suggesting that should negative indirect effects with biological control agents occur they would likely be transient and closely linked to population dynamics as influenced by abiotic factors like temperature. Despite identifying potential negative interactions using path analysis, we saw no apparent competition following the insertion of a weed biological control agent into a community that contains an ecological analog. In this example, the primary negative interaction was biotic resistance to Megamelus scutellaris from attack by Kalopolynema ema. Adopting weed management tactics that emphasize efficacy, sustainability and environmental benevolence argue for the use of classical biological control when appropriate.

Mercury uptake and accumulation by four species of aquatic plants

Food-handling ability was examined in Florida manatees (Trichechus manatus latirostris) feeding on different species of aquatic plants during controlled feeding trials. Subjects were presented with freshwater (Hydrilla verticillata, Myriophyllum spicatum, and Vallisneria americana) and marine species (Syringodium filiforme and Thalassia testudinum) of aquatic plants. Food handling was quantified by measuring length of cyclic movements (or feeding cycles) of perioral bristles that manatees use to introduce food into the mouth. Mean feeding-cycle lengths varied, depending on body size of the subject and species of plant being consumed. Rates of food introduction derived from mean feeding-cycle lengths were similar to chewing rates reported by other researchers. Manatees consumed plants with tubular stems and numerous branches faster than plants with flat blades. Food-handling time using perioral bristles differed, depending on the species of plants consumed and was reflected in the mean feeding-cycle length.

Aquatic plants are generally considered as breeding grounds for mosquitoes and other harmful vectors of diseases. However, in recent years, some research has been carried out to test their significance as sources of antimicrobial lead molecules. The aim of this research was to study the phytochemical composition of local aquatic plant species and test their antimicrobial effect against selected bacterial strains. Three different aquatic plant samples were collected from a large water body near Dhaka. Ethanol and ethyl acetate extracts of the plant species: Eichhornia crassipes, Pistia stratiotes, and Spirodela polyrrhiza were tested against Staphylococcus aureus, Salmonella typhi, and Lactobacillus spp. Out of the eight different extracts, only the ethyl acetate extracts prepared from Eichhornia crassipes showed significant anti-microbial activity against Staphylococcus aureus and Salmonella typhi. In disk diffusion tests, zone of inhibitions of ethyl acetate extracts of Eichhornia crassipes leaves and stems were 8.00 ± 0.5 mm and 7.83 ± .29 mm respectively. In well diffusion tests, zone of inhibitions of ethyl acetate extracts of Eichhornia crassipes leaves and stems were 18.00 mm and 20.00 mm respectively. Zones of inhibition of ethyl acetate extracts of Eichhornia crassipes stems against Staphylococcus aureus were 7.67 ± 0.29 mm and 12.00 mm respectively in disk and well diffusion tests. Zone of inhibition of ethyl acetate extracts of Spirodela polyrrhiza was 8.17 ± 0.29 mm against Staphylococcus aureus in disk diffusion tests. No extracts showed any antimicrobial potential against Lactobacillus. Phytochemical composition analysis showed the presence of alkaloids, flavonoids, steroids, phenolics, tannins, glycosides, and cardiac glycosides in the different ethanol and ethyl acetate extracts. Tannins were absent in all extracts and saponins were absent in all ethyl acetate extracts.
 Bangladesh J Microbiol, Volume 35 Number 1 June 2018, pp 7-11

Aquatic plants are important primary producers that affect the nutrient cycling in shallow coastal areas. How benthic communities composed of different plant species affect community metabolism and N fluxes is however, poorly understood, and in situ quantification is scarce. To study primary production and water-sediment N fluxes in a benthic community consisting of various aquatic vascular plant species, diel field experiments were conducted in the Baltic Sea. Nine plant species were incubated in situ with bare sediments as control. The aim was to investigate diel community (including vascular plants, epiphytes, infauna, phytoplankton, and phytobenthos) and biomass-specific metabolism and nitrogen fluxes among different plant species within a benthic community and to compare N fluxes between vegetated and bare sediments. The net production differed between different plant species, while the overall respiration was unaffected by the plant species present. There were no discernible differences in inorganic N fluxes between the different plant species within the benthic community and vegetated and bare sediments, whereas DON fluxes differed significantly. These results demonstrate that aquatic plant species have varying effects on ecosystem processes. Inherent differences between plant species add significant complexity to benthic functional diversity and highlight the important role that species-rich vegetated habitats play for ecosystem functioning in shallow coastal areas.

Clarifying the functional consequences of intraspecific trait variability in response to interacting trophic levels would provide a significant improvement in our understanding of above‐ground–below‐ground linkages. In particular, the effects of grazing on plant traits may translate into altered litter quality, with potentially important consequences for litter‐feeding decomposers. Plant and litter variability in response to grazing is expected to depend on soil fertility levels, with tolerance and defensive strategies more commonly expressed on fertile and poorer soils, respectively. However, how grazing and fertility interactively alter litter quality and palatability to detritivores has not been explored yet. We conducted a cafeteria experiment with three common millipede (Diplopoda) species feeding on leaf litter from two plant species, the grass Bromopsis erecta and the forb Potentilla verna. Each millipede was offered a binary choice between litter types produced by the same plant species, but sampled in plots with distinct herbivory and fertilization status: litter originating from grazed areas or from 1‐year sheep exclosures, both in native areas and in adjacent paddocks that received chemical N and P fertilization, as well as litter from a 25‐year sheep exclosures in the native area. We found that fertilization and herbivore exclusion interactively affected Bromopsis litter quality and palatability, whereas Potentilla was much less affected. Bromopsis litter palatability was not affected by grazing when litter was collected in native plots, except for the long‐term exclosure which led to low palatability. In contrast, and in line with our expectations, herbivory was associated with much higher palatability in fertilized plots. The changes in palatability were associated with important alterations of litter quality. Overall, our study demonstrates that intraspecific variation in litter can have profound consequences for soil functioning. It emphasizes the role of grazing as a key, but plant species‐specific factor controlling litter intraspecific variability, and its complex interaction with soil fertility level. Moreover, our results advocate for a better understanding of the response of the different organisms involved in the decomposition process, in particular litter‐feeding macro‐detritivores. We encourage future studies aiming at disentangling the various and complex relationships between above‐ground processes such as herbivory and soil functioning.

A plant species in a community often grows with some other plant species. While many studies have assessed interspecific interactions between two target plant species, few have considered the impacts of the other plant species (e.g., the third, fourth, and fifth plant species) on these interactions. To assess the impacts, we grew one seedling of each of the five herbaceous plant species that are common in China (Cynodon dactylon, Plantago asiatica, Taraxacum mongolicum, Nepeta cataria, and Leonurus japonicus) alone (no competition) or with one seedling of one, two, three, or four of the other species. The presence of a neighbor plant generally reduced the growth of the target species, suggesting that the interspecific relationships were mostly competitive. The presence of other neighbor species (the third, fourth, and fifth species) could alter the interspecific interactions between two target species, but such effects varied depending on both the identity of the target species and the identity of the other species. Additionally, the effects of the third species depended little on the presence of the fourth and fifth species. We conclude that interspecific interactions between two plant species are commonly regulated by the presence of other species, facilitating species coexistence. However, our findings do not support the idea that the impacts of the fourth and fifth species on interactions among three plant species are common. This study highlights the complex interactions among multiple plant species within a community and also the importance of including these high-order interactions when modelling community dynamics and species coexistence.

We laid 4 trial areas: 2 km over the flow of the river in the village of Zaturtsi (target № 1), in Kovel (target № 2), in the village Bachiv, over 500 m below the сleaning construction (stations № 3), the fourth behind the Buzaky village, near the mouth (target № 4) for the study and analyze the species composition of higher aquatic and coastal-aquatic plants of the river Turija and identification of sensitive species to pollution. As the result of the research it was found that the species composition of Turija`s flora concluded 59 species of aquatic and coastal aquatic plants belonging to three departments (Equisetophyta, Polipodiophyta and Magnoliophyta), 25 families and 39 genera. The families of Potamogetonaceae – 5 (8.47%) and Cyperaceae – 9 (15.25%) concluded the greatest number of species. The highest species diversity was detected in the area № 2 in Kovel – 33 species of higher aquatic and coastal-aquatic plants, and less in Buzaky (area № 4), where we have identified 26 species. Only 7 species of plants, which were on all test areas were found. 16 species were found only in one are, 22 species were found in half of the area. The largest group of plants, according to their distribution in the reservoirs is the coastal air-water vegetation – 39 species (66,10 %). A group of plants with floating leaves includes 10 species (16,95 %), 10 species (16,95 %) belong to submerged plants. It was found 14 species of higher aquatic plants that were sensitive to pollution. Three of these species are with a ratio value of the indicator (zi) 3, 2 – with the ratio value of the indicator (zi) 2 and 9 species are with a ratio value of the indicator (zi) 1.

The transfer of seed‐containing hay is a restoration measure for the introduction of plant species of local provenance. We investigated the effect of hay transfer on species richness and on long‐term establishment of target plant and grasshopper species on former arable fields with and without topsoil removal in comparison to reference sites in a nature reserve. Plant species richness, the number of target plant species, and Red List plant species were significantly positively affected by hay transfer, both on the scale of whole restoration fields and on permanent plots of 4 m2. Eight years after the start of the restoration, only few of the transferred plant species had disappeared and some target species were newly found. Grasshoppers were affected not by hay transfer but by topsoil removal. The proportion of target grasshopper and plant species and Red List grasshopper species was higher on topsoil removal sites with low standing crop and high cover of bare soil than on sites without soil removal. On topsoil removal sites without hay, however, plant species richness was very low because of the slow natural dispersal of the target species. Vegetation and grasshopper communities still differed between restoration fields and the nature reserve. Nevertheless, our results indicate that the transfer of autochthonous seed‐containing hay is a successful method to establish species‐rich grasslands with a high proportion of target species.

Purwodadi Botanic Garden is one of the botanic gardens in Indonesia, located in Pasuruan, East Java. Purwodadi Botanic Garden (PBG) is an ex-situ plant conservation area that serves five main functions: conservation, research, education, ecotourism, and environmental services. Purwodadi Botanic Garden features a living collection of plants, primarily terrestrial, but also includes aquatic species. Therefore, this study aims to conduct water quality monitoring in aquatic plant ponds and present the experiments of phytoremediation on selected species of aquatic plants. This research employs a mixed-methods approach, combining qualitative and quantitative methods. Data were obtained from direct observation of aquatic plants in the garden, monthly monitoring of water quality in 32 ponds, and the results of phytoremediation experiments from research activities spanning over ten years. Monitoring water quality using water-test kits is inexpensive, easy to use, and yields results quickly. Parameters measured for environmental quality are temperature, humidity, light intensity, pH, TDS, and water temperature. The results show that, out of 32 ponds in the garden, only 12 ponds were found to have aquatic plants. The water quality in ponds with aquatic plants is generally better than in those without aquatic plants, indicating that the aquatic plants in ponds act as phytoremediators in the effort to improve water quality. Purwodadi Botanic Garden contains 25 species of aquatic plants. However, during the observation of the pond, only 15 species of aquatic plants were present. The results of the experiments selected 10 species as phytoremediation agents for both organic and inorganic pollution. The 10 species are Acanthus ilicifolius, Actinoscirpus grossus, Ceratophyllum demersum, Coix lacryma-jobi, Echinodorus radicans, Lemna minor, Ludwigia octovalvis, Pistia stratiotes, Sagittaria lancifolia, and Salvinia molesta. Keywords: aquatic, garden, phytoremadiation, plant, water

Phytoremediation is a method of using plants to remove pollutants from contaminated soil or waters. Several species of aquatic plants have been used in reducing pollutants in the waters. The purpose of this study was to determine the effectiveness of three species of aquatic plants as phytoremediators to reduce levels of COD and BOD of liquid waste, the effect of tofu liquid waste on the fresh weight of the species, and the chlorophyll of the plants content after treatment. Data obtained through experimental methods through a quantitative approach with non-factorial Complete Randomized Design. Data analysis used Analysis of Variance. The results showed that three types of water plants were effectively used as phytoremediator in tofu waste water with the highest percentage of BOD and COD reduction obtained in a combination of Water lettuce (Pistia stratiotes L.) and Yellow velvetleaf (Limnocharis flava L.) which was 99.42%. Besides, liquid tofu waste is effective in an increase in the species chlorophyll content. In brief, the aquatic plant species are effective to reduce COD and BOD levels and to increase of chlorophyll content and fresh weight of the species.

Aquatic ecosystems in Botswana have been under threat by the aquatic alien invasive plant species viz., salvinia Salvinia molesta Mitchell, water lettuce Pistia stratiotes L., and water hyacinth Eichhornia crassipes (Mart.) Solms-Laub. While salvinia has been termed the major threat to the Botswana wetlands, water lettuce and water hyacinth are considered to be of minor importance. This review presents the species biology, distribution, historical spread, negative impacts, control achieved right from their discovery in the country by referring to their control and management in the world. Having infested the Kwando-Linyanti-Chobe Rivers in the 1970s, salvinia was initially tried by the use of herbicides, paraquat and glyphosate, between 1972 and 1976. With the discovery of the host specific biological control weevil Cyrtobagous salviniae Calder and Sands in 1981, the weevil was introduced by Namibians on Kwando and Chobe Rivers in 1983 and by Botswana in 1986 in the Okavango Delta. While the control was slowly establishing in Kwando-Linyanti-Chobe Rivers, it became apparent that lakes and perennial swamps within and outside Moremi Game Reserve of the Okavango Delta were infested with salvinia from 1992 onwards. With continuous and sustained liberation of the weevil in the Kwando-Linyanti-Chobe Rivers and in the Okavango Delta between 1999 and 2000, salvinia control was achieved by 2003, and since then the weevil constantly keeps the weed at low levels. The success is mainly due to sustainable monitoring through the application of physical and biological control methods. However, salvinia is still threatening the Okavango Delta due to factors such as tourism activities, boat navigation fishing and transporttion by wild animals. The first occurrence of water lettuce was recorded on Kwando and Chobe Rivers in 1986. Its biocontrol weevil Neohydronomous affinis Hustache was released in the year 1987. The weevil became extinct in Selinda Canal and Zibadianja Lake on Kwando River due to dry and wet events for over 10 years and the weed had been under control biologically on Chobe River. Having surface covered the Selinda and a part of the Zibadianja in high flood and rainfall in 1999/2000 season, research was undertaken to contain water lettuce, which led to its eradication by 2005. Regular physical removal of the water lettuce prior to fruit maturity is an effective method of control or eradicating the weed in seasonal water bodies. The Limpopo Basin (shared by Botswana, South Africa, Zimbabwe and Mozambique) has become vulnerable to water hyacinth infestation. Water hyacinth infested the trans-boundary Limpopo River in 2010 sourced from Hartbeesport Dam on Crocodile River in South Africa. Botswana and South Africa have been consulting each other to implement integrated control of the weed jointly in the Limpopo River. Water hyacinth could be a continuous threat to the dams and the rivers in the Limpopo basin if its control is not taken seriously. These three species are found growing in Botswana in a range of pH between 4.5 and 10.3 and in the range of conductivities between 20 and 580 µS cm-1. Range of soluble nitrates, phosphates and potassium in the habitats of salvinia infestations were 0.02 to 1.5, 0.01 to 1.78 and 0.3 to 6.92 mg L-1 respectively. Water lettuce infestation in the seasonal Selinda Canal had a maximum of 4.7 mg L-1 nitrates, 2.8 mg L-1 phosphates and 7.9 mg L-1 potassium. Nevertheless, these three nutrients were in the range of 0.41 to 9.56 mg L-1, 0.2 to 2.9 mg L-1, and 7.7 to 11.53 mg L-1 respectively in the Limpopo River where water hyacinth infestations were observed. These nutrients were considerably high during decomposition phase of biological control of weeds. The Government of Botswana “regulates the movement and importation of boats and aquatic apparatus, to prevent the importation and spread of aquatic weeds both within and from the neighboring countries” by “Aquatic Weed (Control) Act” implemented in 1986. These measures, combined with communities, conservation groups, NGOs and public awareness campaigns, have highlighted the gravity of aquatic weeds spreading into wetlands, dams and other water bodies. In conclusion, the Government of Botswana is committed and supportive through the Department of Water Affairs in protecting the wetlands of the country efficiently and prudently.

1. Indirect interactions between populations of different prey species mediated by a shared predator population are known to affect prey dynamics.2. Depending on the temporal and spatial scale, these indirect interactions may result in positive (apparent mutualism), neutral or negative effects (apparent competition) of the prey on each other's densities. Although there is ample evidence for the latter, evidence for apparent mutualism is scarce.3. The effectiveness of using one species of predator for biological control of more than one pest species depends on the occurrence of such positive or negative effects.4. We used an experimental system consisting of the two prey species Western flower thrips (Franklineilla occidentalis Pergande) and greenhouse whitefly (Trialeurodes vaporariorum Westwood) and a shared predator, the phytoseiid mite Amblyseius swirskii Athias‐Henriot. We released all three species on the same plant and studied their dynamics and distribution along rows of plants.5. We expected that the more mobile prey species (thrips) would escape temporarily in the presence of the other prey species (whitefly) by dispersing from plants with the predator. The predator was expected to disperse slower in the presence of two prey species because of the higher availability of food.6. Evidence was found for slower dispersal of predators and short‐term escape of thrips from predation when whiteflies were present, thus confirming the occurrence of short‐term apparent mutualism.7. The apparent mutualism resulted in a cascade to the first trophic level: a higher proportion of fruits was damaged by thrips in the presence of whiteflies.8. We conclude that apparent mutualism can be an important phenomenon in population dynamics, and can significantly affect biological control of pest species that share a natural enemy.

Alien species can drastically disrupt ecological processes such as those involving plant–pollinator interactions, performing central roles that may affect the structure of native pollination networks. However, most studies to date have focused on a single trophic level of alien species, evaluating either the impacts of an alien pollinator or an alien plant species, and have neglected their joint effects on the seasonal dynamics of mutualistic networks. Here, we aim to fill this gap by investigating how alien plant and flower visitor (here used as a proxy for pollinator) species structure temporal networks, and how these species affect the beta‐diversity of interactions across a flowering season. Our study system is located in the South Island of New Zealand, where 68% of the sampled plant species and 14% of the flower visitor species that interact with them are alien. Alien flower visitor species exhibited higher interaction degree, specialization and strength than their native counterparts, while alien plant species showed the opposite pattern. We found that invader complexes (in which alien species interact significantly more with each other than with native species) were established across the season, and interactions involving alien plant species were the main connectors of the temporal networks. Both alien plant and flower visitor species increased total interaction turnover through the flowering season by promoting interaction rewiring in the case of alien plants and by increasing species turnover in the case of alien flower visitors. Synthesis. This study provides one of the first empirical reports of alien species shaping the seasonal dynamics of plant–flower visitor networks. We demonstrate that the presence of alien species may simultaneously lead to a homogenization of plant species composition and increase the diversity of plant–flower visitor interactions through a flowering season. Additionally, we highlight the importance of considering the role of different trophic levels when analysing the impact of alien species in plant–flower visitor communities. Overall, our findings suggest that management strategies should pay particular attention to the timescale at which interactions with alien species dissolve or form, and to the consequences and drivers of such seasonal dynamics.

Freshwater ecosystems are widely recognized as a significant global biodiversity hotspot. Unfortunately, they are also highly vulnerable to the expansion of invasive aquatic species, whose spread is considered among the top threats to these ecosystems. Especially problematic are alien aquatic plants species whose rapid growth often disrupts local communities and may even alter physicochemical conditions of a given freshwater ecosystem. Since most of invasive aquatic plants are native to tropical regions of the world, their occurrence in some Central and Eastern Europe countries was, until relatively recently limited by cold winters typical for this part of the continent. However, in the last two decades, we have observed a sharp increase in these species abundances in this part of Europe, which can be linked to the warmer winters resulting from the ongoing climate change. In our study, we examine the effects of temperature changes resulting from global warming on the development and occurrence of several aquatic alien plant species. Our analysis is based on our unique data base that contains extensive information about all currently known alien vascular aquatic plant species present in Poland as well as their precise location. This data is notable for being the first such database summarizing the current status of aquatic plant invasions for this country. Based on it, as well as temperature data from the last several years, we created generalized additive models (GAM) for temperature response for each of 15 aquatic alien plant species known for Poland. Our results show a strong relationship between rising temperatures and the spread of certain species, i.e. Azolla filiculoides. Furthermore, spread of such species as Elodea nuttallii and Lemna turionifera in Poland does not rely strongly on temperature. Presence of some species was found to be highly dependent on highly thermally altered or thermally contaminated waters, i.e. Vallisneria spiralis, Hygrophila polysperma, and  thus their occurrence is still limited only to such locations. Our results confirm the major role of elevated temperatures and thermal modification of waters in the distribution of alien aquatic plants.