Exotic Macrophyte Research Articles

Insights into the fauna associated with Egeria densa at the upper section of the international Minho River estuary (NW Iberian Peninsula) 3 decades after its establishment

The macrophyte Egeria densa Planchon, 1849 is a freshwater plant native to the subtropical regions of South America. Fast vegetative reproduction and efficient dispersal allow this species to form extensive beds that produce high levels of oxygen in freshwater ecosystems, generating microhabitats that act as refuge and nursery for an array of organisms, increasing sedimentation and light availability. Despite its undisputable ecological role, it is considered invasive and is present on all continents except Antarctica with the first records in Europe occurring at the 20th century. At the international Minho River (NW Iberian Peninsula), the observation of its presence was noted in the 1990s and is now an established population in this ecosystem. This study is the first descriptive-taxonomical assessment of the associated fauna with the exotic macrophyte E. densa, using both morphological and molecular approaches, three decades after its establishment in the international Minho River. Results indicate the presence of a faunal assemblage, composed a total of 20 identified species, including platyhelminths, hydrozoans, bryozoans, molluscs (Gastropoda), annelids (Oligochaeta and Hirudinea), crustaceans (Ostracoda, Copepoda, Branchiopoda and Amphipoda), aquatic mites and insects. Paludicella aff. articulata (Ehrenberg, 1831), Girardia sinensis Chen & Wang, 2015, Lebertia insignis Neuman, 1880 and Ceriodaphnia rigaudi Richard 1894 are recorded for the first time in Portugal.

Uma revisão global sobre traços funcionais de macrófitas invasoras e sua relação com o sucesso no processo de invasão

Abstract: Aim Biological invasions by exotic macrophytes represent one of the main reasons for biodiversity and ecosystem changes in aquatic ecosystems. The reasons for their ability to succeed in new environments have been of ecological interest in the last years. We made a global review, aiming to describe functional traits related with invasiveness of macrophytes. Methods Our search was performed using keywords regarding invasive macrophytes and functional traits. We related the group traits of invasive species with their probability of species invasion success in new localities (invasiveness). We also performed a nestedness analysis that helped us to see which species possessed the higher number of traits related to invasiveness, as well as which traits were more common among the invasive species. Results Traits most often related to invasiveness were those indicating growth (94.5%) and reproduction (90.1%). Nearly 70.4% of invasive macrophytes traits were related with the probability of invasion success. Invasive species had a higher number of morphological and biotic interaction traits related with invasiveness than native species. Our nestedness analysis indicated a low degree of nestedness, but showed us that Egeria densa, Elodea canadensis and Elodea nutalli were the species with a wider range of environmental tolerances, explaining their invasibility across ecosystems. Conclusions We summarized and complement existing reviews on the functional traits related to invasion success of macrophytes. We believe this review contributed to the identification of the most common set of traits related with invasiveness, helping to speculate on successful invaders in the future.

A new method for monitoring macrophyte communities in small shallow lakes and ponds

Macrophytes are key to the functioning of small shallow lakes (SSLs) because they maintain a clear water state through numerous positive feedbacks. The composition of macrophyte communities changes under anthropogenic pressures; as a result, tools designed to easily and rapidly assess their structure and composition are increasingly requested. We tested three sampling methods (the S3m sampling method, a stratified method, and a mapped inventory) to monitor macrophytes in 26 SSLs. The effect of each method was evaluated on seven descriptors of macrophyte communities, including the median conservation value. The results were comparable for the three methods, but the stratified method failed to accurately monitor the median conservation value and the number of species present at a low frequency, including exotic and patrimonial species, hence serious consequences for management decisions. S3m was applied to 262 SSLs ranging from 1 m2 to 43 ha in surface area. Generalised additive models were used to investigate the environmental factors correlated with four conservation value or ecosystem functioning descriptors. The S3m method showed that surface area, distance from the source, elevation, and bank verticality were determinants of macrophyte richness. Invasive crayfish impacted the macrophyte richness and the coverage of submerged macrophytes, whereas fish presence increased the macrophyte richness and the percentage of exotic macrophytes and reduced patrimonial interest. S3m was successfully applied to a wide diversity of SSLs in France. It proved to be rapid, reproducible, and representative for monitoring macrophytes in SSLs. Therefore, it should be applied for SSL management.

Invasion of water hyacinth and water lettuce inhibits the abundance of epiphytic algae

AbstractAimThe invasion of exotic macrophytes causes native biodiversity loss in aquatic ecosystems of China. However, the influence of invasive free‐floating macrophytes on epiphytic algal communities has rarely been reported, especially in comparison with those of native free‐floating macrophytes.RegionSouthern China.MethodsWe investigated the interrelationship between epiphytic algal communities on the roots of three free‐floating macrophytes [two invasive species (Eichhornia crassipes and Pistia stratiotes) and one native species (Hydrocharis dubia)] and environmental factors in 40 natural freshwater ecosystems throughout southern China. We also tested the relationship between allelochemicals from the macrophytes and epiphytic algae. A mesocosm experiment was conducted to verify the discoveries of the field investigation.ResultsThe abundance of epiphytic algae on the invasive macrophytes was lower than that on the native species in the field investigation and mesocosm experiment. Macrophyte traits were the main factor explaining the epiphytic algal abundance in both the field investigation and mesocosm experiment. In linear models, the slopes of epiphytic algal abundance were lower across gradients of native macrophyte biomass and coverage than across gradients of invasive macrophyte biomass and coverage. The allelochemical contents secreted by the invasive macrophytes were significantly higher than those secreted by the native species. The composition of allelochemicals was another factor that drove the decrease in epiphytic algal abundance. Among the allelochemicals, organic acids and alkaloids were abundant.Main ConclusionsThe inhibitory effect of two invasive free‐floating macrophytes on epiphytic algae is stronger than that of the native macrophyte H. dubia. The main reason for this finding is that the invasive macrophytes have greater biomass and occupied more space, resulting in greater limitations on spatial niches and resources. Moreover, invasive macrophytes release more allelochemicals than native macrophytes, leading to stronger inhibitory effects on epiphytic algae.

Seagrass (Halophila stipulacea) invasion enhances carbon sequestration in the Mediterranean Sea.

The introduction and establishment of exotic species often result in significant changes in recipient communities and their associated ecosystem services. However, usually the magnitude and direction of the changes are difficult to quantify because there is no pre-introduction data. Specifically, little is known about the effect of marine exotic macrophytes on organic carbon sequestration and storage. Here, we combine dating sediment cores (210 Pb) with sediment eDNA fingerprinting to reconstruct the chronology of pre- and post-arrival of the Red Sea seagrass Halophila stipulacea spreading into the Eastern Mediterranean native seagrass meadows. We then compare sediment organic carbon storage and burial rates before and after the arrival of H. stipulacea and between exotic (H. stipulacea) and native (C. nodosa and P. oceanica) meadows since the time of arrival following a Before-After-Control-Impact (BACI) approach. This analysis revealed that H. stipulacea arrived at the areas of study in Limassol (Cyprus) and West Crete (Greece) in the 1930s and 1970s, respectively. Average sediment organic carbon after the arrival of H. stipulacea to the sites increased in the exotic meadows twofold, from 8.4±2.5gCorg m-2 year-1 to 14.7±3.6gCorg m-2 year-1 , and, since then, burial rates in the exotic seagrass meadows were higher than in native ones of Cymodocea nodosa and Posidonia oceanica. Carbon isotopic data indicated a 50% increase of the seagrass contribution to the total sediment Corg pool since the arrival of H. stipulacea. Our results demonstrate that the invasion of H. stipulacea may play an important role in maintaining the blue carbon sink capacity in the future warmer Mediterranean Sea, by developing new carbon sinks in bare sediments and colonizing areas previously occupied by the colder thermal affinity P. oceanica.

Les macrophytes indigènes et exotiques : mieux connaître pour mieux gérer

Lacs et étangs du littoral aquitain abritent des plantes aquatiques visibles à l’œil nu (macrophytes) inféodées aux hydrosystèmes oligotrophes sableux peu profonds, incluant des espèces rares, endémiques ou présentes habituellement dans les lacs d’Europe du Nord. Depuis une quarantaine d’années, ces plans d’eau sont également le lieu de développements plus ou moins importants de macrophytes exotiques à caractère envahissant. Ces plantes peuvent former des herbiers denses susceptibles de créer localement des envahissements importants dès que les conditions environnementales leurs sont favorables, menant parfois à la colonisation quasi totale de la superficie de certains petits étangs. L’obstacle que représentent les herbiers denses dans la pratique de certains usages récréatifs et les interrogations liées à leurs impacts potentiels sur les espèces indigènes et le fonctionnement écologique des limnosystèmes, ont mené gestionnaires et hydrobiologistes à établir une stratégie commune visant à acquérir des connaissances sur ces "nouvelles" espèces, et à mettre en œuvre des solutions de gestion. À partir de la fin des années 1980, le Syndicat Mixte Géolandes et l’Irstea-Cemagref (désormais l’INRAE) ont collaboré pour établir des diagnostics des espèces présentes et des sites colonisés, pour élaborer ensuite un plan de gestion dédié à la régulation adaptée de chaque espèce en fonction des enjeux identifiés, et à l’entretien régulier des zones traitées pour éviter toute recolonisation massive. Depuis, cette collaboration perdure, le dialogue s’opérant sur la politique de gestion adoptée par le Syndicat Mixte, s’appuyant sur un réseau de référents locaux coordonnant les opérations de surveillance et d’entretien confiées aux collectivités locales avec le soutien technique et financier du Syndicat. Elle s’appuie également sur l’analyse à long terme des dynamiques des plantes et sur le développement de techniques d’échantillonnage et de prédiction de leur distribution potentielle à fine échelle. Ainsi, les questions de gestion alimentent en continu les questions de recherche scientifique, pour tenter de répondre aux interrogations actuelles et émergentes liées à la présence des végétaux dans les plans d’eau.

Experimental evidence that CO2 and nutrient enrichment do not mediate interactions between a native and an exotic free-floating macrophyte

We investigated the effect of CO2 and nutrient enrichment on competition between two free-floating fern species that co-occur in south-eastern Australia—native Azolla filiculoides and invasive exotic Salvinia molesta. The species were grown in monoculture and competition in a glasshouse experiment where the nutrient medium was replaced weekly to simulate a dynamic system. We found that the relative growth rate (RGR) of both species was greater under high resource conditions, with neither showing a suppressive response due to competition. On the contrary, A. filiculoides had a facilitative effect on S. molesta. In addition, A. filiculoides gained more biomass under high resource conditions relative to S. molesta and the opposite was true under low resource conditions. We conclude that [CO2] and nutrient concentration did not mediate competition between the species but instead influenced RGR independent of competition. These findings suggest that species composition in dynamic water bodies under future conditions may be determined by the species’ responses to environmental changes rather than by changes in competitive interactions.

Response of Macrophyte Traits to Herbivory and Neighboring Species: Integration of the Functional Trait Framework in the Context of Ecological Invasions.

With the increase in the number of introduced species each year, biological invasions are considered as one of the most important environmental problems for native biodiversity. In invaded habitats, the establishment of exotic plant species depends on the abiotic and biotic environment. Herbivores and neighboring plants (native or exotic) comprise an important part of the latter. Herbivores cause trophic and non-trophic damage to focal plants, which respond to herbivory by varying their different traits quantitatively (e.g., growth rate and biomass changes) and qualitatively (e.g., variation in morphological and chemical defenses strategies affecting plant palatability). Neighboring plant species also affect functional traits and the fitness of focal plant species, thus herbivore effects on a focal plant could also depend indirectly on the palatability and defensive traits of the neighboring species inside the community. Here, in a first step toward the integration of associational susceptibility/resistance theories in the field of ecological invasion, we performed a microcosm experiment to consider the effects of an exotic crayfish on the growth rate, morphological traits and damage level of three macrophytes (two exotic, one native) growing in pairwise combinations. We found that (i) the response to herbivore presence and to neighboring species identity seemed to be species specific, and (ii) crayfish enhance the fragmentation rate of the two exotic macrophytes Ludwigia grandiflora and Egeria densa in the presence of the native macrophyte Myriophyllum spicatum, which could indirectly facilitate their invasion success. Indeed, fragmentation can increase dispersal abilities of the exotic macrophytes considered in this study as they are able to generate new plants from their fragments. However, our results showed that the interaction herbivore-neighbor species was hardly significant. Our paper presents some first results on associational resistance/susceptibility and lays the foundation for developing a general framework that combines plant community ecology and biological invasion ecology to explain invasive species success.

Fragment type and water nutrient interact and affect the survival and establishment of Myriophyllum aquaticum

Myriophyllum aquaticum is a semi-submerged exotic macrophyte that was introduced to China for many years. This species may be found in an emergent form in aquatic environments or in an amphibious form under drained conditions. Nuisance growth of this species has often been attributed to excessive amounts of nutrients. Therefore, we tested the following hypotheses: (1) high nutrient availability facilitates the establishment of M. aquaticum and (2) fragment type interacts with nutrient availability to determine the colonization and regeneration capacities of M. aquaticum. Two types of fragments were grown in water solutions with two levels of phosphorous. After 3 weeks, the survival rates showed no significant difference between the phosphorous treatments. However, emergent fragments showed higher RGR in the low and high phosphorous treatments than amphibious fragments. In addition, emergent fragments also showed higher regeneration capacities, indicating higher invasiveness in emergent fragments compared to amphibious fragments. Moreover, the high phosphorous concentration caused emergent fragments to produce more branches, indicating that nutrient availability may increase M. aquaticum propagule pressure. Our study highlights that nutrient supply increased emergent fragment establishment and shaped the invasion dynamics of macrophytes, which could help predict the spread and potential impact of exotic macrophytes in natural aquatic ecosystems.

STATUS OF THE INVASION OF A POACEAE SPECIES IN TROPICAL SEMIARID RESERVOIRS

ABSTRACT The species of the Urochloa genus, exotic and infesting in Brazilian waters, are known to be invasive and dominant, occupying from humid, shallow areas, and irrigation canals to margins of deep reservoirs. This paper hypothesis that less depth reservoirs have higher infestation rate and higher biomass of U. arrecta. The objectives were to measure the percentage of occurrence of exotic macrophyte U. arrecta in 40 ecosystems from the Mamanguape basin (Paraíba, Brazil) and determine the infestation of the species in two reservoirs. The acquired data were geo-referenced with the ArcGIS software (v. 9.3). A covariance analysis was performed using the R program (The R project is Statistical Computing). The results showed large spatial distribution of the species, indicating that reservoirs may act as steppingstones in the landscape, in a regional scale. The hypothesis of biotic acceptance is seen as a relevant factor in explaining the presence of the species with low percentage of occurrence in 37 out of the 40 sampled ecosystems, being observed only in areas prone to the colonization of native and naturalized macrophytes, in banks and points of lower declivity, in both spatial scales studied. Thus, factors such as environmental instability (promoted by intermittent or prolonged desiccation of the habitat), shadowing and declivity of the reservoirs synergistically acted on exotic and native species.

Insect herbivory on native and exotic aquatic plants: phosphorus and nitrogen drive insect growth and nutrient release

Eutrophication and globalisation facilitate the dominance of exotic plants in aquatic ecosystems worldwide. Aquatic omnivores can provide biotic resistance to plant invasions, but little is known about whether obligate aquatic herbivores can do the same. Herbivores such as insects can decimate aquatic vegetation, but may not be able to consume exotic plants due to their more or less specialised nature of feeding. We experimentally tested the larval feeding of an aquatic insect, the moth Parapoynx stratiotata, on eleven submerged plant species, from either native or exotic origin. We also tested whether insect herbivory stimulates nutrient and organic matter release, thus affecting water quality. Larvae of P. stratiotata consumed seven out of eleven plant species, and their growth was related to plant nutrient content and stoichiometry. However, larvae had no preference for either native or exotic macrophytes, and their plant preference was not related to the measured plant traits, but was possibly driven by secondary metabolites. Through plant consumption, caterpillars induced brownification and phosphate release, and the intensity thereof varied among plant species, but not between native and exotic plants. In conclusion, P. stratiotata showed strong feeding preferences demonstrating that aquatic insects can directly and indirectly alter water quality and vegetation composition.

Effect of light on particulate and dissolved organic matter production of native and exotic macrophyte species in Patagonia

Biological invasions are one of the main drivers of changes in ecological features in aquatic environments. Invasive alien species may have far-reaching effects on the host environment that need to be explored. In this study, we compared particulate and dissolved organic matter (POM and DOM) production from two common Patagonian wetland plants, one native (Eleocharis pachycarpa) and one exotic (Potentilla anserina), under different light conditions (exposed or not to ultraviolet radiation (UVR+, UVR−) and darkness). Our results indicated that when exposed to UVR both macrophytes differed in their POM production and DOM release: while in E. pachycarpa we observed an increase in the POM production P. anserina released significantly higher amount of DOM. The DOM produced by the exotic species showed lower photoreactivity, and had more colour than that produced by the native E. pachycarpa. The invasion by macrophytes may produce changes in the stoichiometric balance and ecological relationships that could modify the characteristics of wetland food web.

Differential aerobic decomposition between a native and exotic macrophytes of tropical reservoirs.

Differential aerobic decomposition between a native and exotic macrophytes of tropical reservoirs.

Leaves of Vallisneria Finds Source to Anti Dermatitis: Enriching Wetland Ecosystem

The renaissances of phyto-medicines lead to a resolute search of potential medicinal plants worldwide. In this perspective, predominantly, terrestrial allelochemistry has been an imperative tool to evaluate the drug potentiality of a plant. However, in aquatic ecosphere, the pharmaceutical evaluation of the aquatic macrophytes is an emerging aspect. Our study seeks to explore the curative traits of the exotic macrophyte, Vallisneria spiralis L. (Hydrocharitaceae), a perennial stoloniferous species and a key ecological community in freshwater wetland ecosystem. It is commonly used as aquarium plant and inhabits both in lentic and lotic environment of tropical and sub-tropical regions worldwide. Being rapid colonizers of aquatic ecosystem, literature study states the leaves of the macrophyte can excrete special function groups that can absorb, filter and precipitate chemical compound of water and through the auxiliary function of the microorganism. Considering these significances, we have extracted the leaf leachates of Vallisneria in 80% ethanol which had been purified by solid-liquid extraction process and further crystallized and subjected to biochemical analysis viz; phenols, flavonoids and tannins followed by antioxidant scavenging and microbial screening. Further the isolated compound was subjected to Mass and Fourier Infra-red Spectrometry. Comprehensively, all the experimental assays infer that Vallisneria leaves contain bioactive compound with mol wt. m/z 359 structured with microbial growth inhibiting functional groups which were found fungicidal against Malassezia globosa - the dandruff causing dermatitis fungus.

An exotic macrophyte bed may facilitate the anchorage of exotic propagules during the first stage of invasion

The success of invasive macrophytes is due to the ability of introduced fragments to survive, regenerate and colonise freshwaters. In this study, carried out in an experimental garden, we evaluated: (i) the ability of Myriophyllum aquaticum fragments with or without an apex, to survive and colonise and (ii) the effects of a macrophyte bed on the colonisation success of two non-native species (Ludwigia grandiflora, M. aquaticum). Fragments of M. aquaticum with apical stems had the highest survival rate (85 vs. 62%) and colonisation abilities (i.e. 9% of rate of anchorage with a macrophyte bed). The anchorage rate of L. grandiflora was stimulated by the presence of the non-native Elodea canadensis and the relative growth rate of M. aquaticum fragments was higher in the presence of a L. grandiflora bed. Facilitation may enhance the colonisation of some non-native species during the first stage of invasion (colonisation and regeneration). However, the presence of a macrophyte bed limits the chances of L. grandiflora rooting in the sediment. This result suggests that spatial competition may occur at the beginning of growth in shallow waters. Competitive or facilitative interactions between neighbouring species depend both on the introduced species and on macrophyte bed composition.

Regime shifts of Cruces River wetland ecosystem: current conditions, future uncertainties

During April-May 2004 the Cruces River wetland ecosystem, located in Valdivia (40oS), southern Chile, was described as shifting from a clear water regime, dominated by the exotic macrophyte Egeria densa, to turbid waters and absence of submerged macrophytes. We analyzed the trophic status and ecological regime of the wetland from November 2011 through January 2013. The trophic status was determined comparing values of selected variables (nutrients, chlorophyll-a and transparency) with OECD criteria. The ecological regime was determined comparing the same variables with the criteria proposed by Ibelings et al. (2007). We further compared the concentration of nutrients and suspended solids with previous measurements. Current trophic status of the wetland is between eutrophic and hypereutrophic, as shown by results, and its ecological regime intermediate, between clear and turbid waters, with a considerable risk of returning to turbid waters. In this article we discuss the potential relationship between the watershed land use (agriculture, cattle feeding and forestry), the change in wetland's trophic level and future conditions.

The propagule supply, litter layers and canopy shade in the littoral community influence the establishment and growth of Myriophyllum aquaticum

The exotic macrophyte species Myriophyllum aquaticum (Vell.) Verdc. is widely dispersed, mainly through stem fragments and rhizomes, in shallow littoral zones in which uniform canopy conditions are created by the pre-existing resident wetland plant species. Therefore, interactions between these two types of asexual propagules and the resident species may occur during the early establishment and growth phases of M. aquaticum. We tested the hypothesis that the establishment and growth of M. aquaticum are affected by three factors: the number of propagules supplied, the presence of a standing biomass of Carex japonica Thunb. and the presence of thick litter layers in the littoral zone. M. aquaticum rhizomes and stem fragments were introduced into a standing biomass of C. japonica in mesocosms using two types of sediments (littoral and sand-clay) and two propagule supply levels. After 4 months, the survival rates of both the rhizomes and stem fragments were high under all of the experimental treatments. The propagule supply positively affected the survival rates and growth of M. aquaticum. The survival of the rhizomes was unaffected by the presence of either C. japonica or littoral sediments, whereas the survival of the stem fragments was reduced by the presence of C. japonica. The presence of litter layers is a primary factor facilitating the growth of M. aquaticum propagules because of the high nutrient content of the litter. In addition, the presence of the standing C. japonica biomass and newly growing Eleocharis yokoscensis (Franch.et Sav.) Tang et Wang (a small ruderal species that, unexpectedly, grew rapidly following the removal of the standing biomass of C. japonica) reduced the growth of the M. aquaticum stem fragments and rhizomes, respectively. Our findings suggest that the loss of vegetative cover resulting from intense cattle herbivory and other factors in littoral zones may accelerate the invasion of M. aquaticum. An effective approach for preventing M. aquaticum invasion is to reduce the propagule supply and prevent propagules from dispersing.

Water Quality Improvement of a Reservoir Invaded by an Exotic Macrophyte

AbstractThe aim of this study was to evaluate the effect of the macrophyte waterhyacinth on the water quality of a reservoir in Colombia. Postinvasion water quality assessments were performed during three different hydrological periods and compared with preinvasion data. The results show that water quality has improved, especially in terms of transparency, showing an increase in Secchi disk values from 0.3 to 2 m (1 to 6.6 ft). The analysis strongly suggests that the improvement in water quality is due to the filtering and precipitation effects provided by waterhyacinth. This case highlights the dilemma of managing an invasive species that provides a beneficial ecological service while posing a high ecological risk.

Merging geospatial and field data to predict the distribution and abundance of an exotic macrophyte in a large Wisconsin reservoir

Geospatial and field data were merged to characterize the invasion of an exotic macrophyte into a large (∼6192 ha), reservoir, the Chippewa Flowage, Wisconsin, USA. Multi-scale analyses provided data for quantitative models of human, abiotic and biotic influences that would explain the presence and abundance of Myriophyllum spicatum L., a widespread, aquatic species. Human and abiotic factors were analysed in a geographic information system and additional abiotic and biotic factors were sampled at 2778 sample points. Using multivariate logistic and multiple linear regressions the relationships between 29 factors and the species’ presence and abundance were quantified. M. spicatum occurred at 181 of 992 vegetated points. M. spicatum abundance was significantly influenced by two geospatial variables (wave action and water-level drawdown) and two site variables (water depth and native species presence). Separate models for shallow and deep water explained 32% and 30% of M. spicatum abundance, respectively (compared to 22.8% using all 181 points). The species’ vertical distribution (range = 0.30–4.27 m) was related to depth of winter drawdown (∼1.3 m on average) and to water depth (an indicator of decreasing light), as well as to shading by floating-leaved macrophytes. Spatial extrapolation of model predictions for M. spicatum presence indicated that a total 940 hectares are at risk for M. spicatum invasion (∼15% of the Chippewa Flowage; about 2.5 times larger than the current distribution).

Use of Macrophytes for Egg Deposition by the Endangered Fountain Darter

Use of habitats for egg deposition by the endangered fountain darter Etheostoma fonticola was evaluated through examination of seven probable microhabitat types in the wild (San Marcos River, Texas) and through laboratory trials with six artificial form-equivalent habitats. Eggs were deposited on native vegetation in the wild; significantly more eggs were found on filamentous algae Rhizoclonium sp. than on Illinois pondweed Potamogeton illinoensis, waterthyme Hydrilla verticillata (an exotic macrophyte), or nonvegetated gravel. Eggs were also found on creeping primrose-willow Ludwigia repens, delta arrowhead Sagittaria platyphylla, and endangered Texas wildrice Zizania texana. Within vegetated habitats, more eggs were deposited on plants growing in sand than silt substrate. This probably corresponds to the habitat requirements for the species; the fountain darter is abundant in slower-moving reaches within the river headwaters, and the presence of silt is an indicator of poor or less-preferred habitat. Results of laboratory trials generally corresponded with field results: larger numbers of eggs were deposited on the form-equivalent Rhizoclonium sp. and L. repens. It is likely that the presence of native macrophytes is necessary for successful fountain darter reproduction.