Diversity In Ponds Research Articles

Sulfate and Dissolved Organic Carbon Concentrations Drive Distinct Microbial Community Patterns in Prairie Wetland Ponds.

Prairie wetland ponds on the Great Plains of North America offer a diverse array of geochemical scenarios that can be informative about their impact on microbial communities. These ecosystems offer invaluable ecological services while experiencing significant stressors, primarily through drainage and climate change. In this first study systematically combining environmental conditions with microbial community composition to identify various niches in prairie wetland ponds, sediments had higher microbial abundance but lower phylogenetic diversity in ponds with lower concentrations of dissolved organic carbon ([DOC]; 10-18 mg/L) and sulfate ([SO4 2-]; 37-58 mg/L) in water. As [DOC] and [SO4 2-] increased, there was an initial decline in abundance but not phylogenetic diversity. Maximum values of both abundance and phylogenetic diversity occurred between 56 and 115 mg/L [DOC] and 5,000-6,000 mg/L [SO4 2-] and decreased thereafter in ponds with 150-180 mg/L and 8,000-14,000 mg/L [DOC] and [SO4 2-], respectively. These findings confirm that environmental variables shape the microbial communities and that key microbial taxa involved in sulfur and carbon cycling dominated these ponds potentially impacting vital biogeochemical processes such as bioavailability of heavy metals, carbon sequestration, and methane emissions.

Community connectivity and local heterogeneity explain animal species co-occurrences within pond communities.

Metacommunity processes have the potential to determine most features of the community structure. However, species diversity has been the dominant focus of studies. Nestedness, modularity and checkerboard distribution of species occurrences are main components of biodiversity organisation. Within communities, these patterns emerge from the interaction between functional diversity, spatial heterogeneity and resource availability. Additionally, the connectivity determines the pool of species for community assembly and, eventually, the pattern of species co-occurrence within communities. Despite the recognised theoretical expectations, the change in occurrence patterns within communities along ecological gradients has seldom been considered. Here, we analyse the spatial occurrence of animal species along sampling units within 18 temporary ponds and its relationship with pond environments and geographic isolation. Isolated ponds presented a nested organisation of species with low spatial segregation-modularity and checkerboard-and the opposite was found for communities with high connectivity. A pattern putatively explained by high functional diversity in ponds with large connectivity and heterogeneity, which determines that species composition tracks changes in microhabitats. On the contrary, nestedness is promoted in dispersal-limited communities with low functional diversity, where microhabitat filters mainly affect richness without spatial replacement between functional groups. Vegetation biomass promotes nestedness, probably due to the observed increase in spatial variance in biomass with the mean biomass. Similarly, the richness of vegetation reduced the spatial segregation of animals within communities. This result may be due to the high plant diversity of the pond that is observed similarly along all sampling units, which promotes the spatial co-occurrence of species at this scale. In the study system, the spatial arrangement of species within communities is related to local drivers as heterogeneity and metacommunity processes by means of dispersal between communities. Patterns of species co-occurrence are interrelated with community biodiversity and species interactions, and consequently with most functional and structural properties of communities. These results indicate that understanding the interplay between metacommunity processes and co-occurrence patterns is probably more important than previously thought to understand biodiversity assembly and functioning.

Impact of freshwater diversions on vegetation in coastal wetlands based on remote sensing derived vegetation index

There exist contrasting results on the impact of large-scale freshwater and sediment diversions on land gain/loss. To improve understanding on the efficacy of diversion projects in restoring coastal wetlands, we aim to evaluate the long-term impacts of diversion-altered salinity and water level on vegetation productivity in coastal wetlands. Two freshwater diversion projects Caernarvon and Davis Pond in Louisiana, U.S. and associated reference sites were selected for inclusion in this study. We implemented multi-level Bayesian models to evaluate 1) how vegetation productivity approximated by Landsat-derived Normalized Difference Vegetation Index (NDVI) in peak biomass season changed over time (pre- and post-construction and operation of the freshwater diversions), and 2) how peak-season NDVI responded to mean and variability of water level and salinity among a suite of factors that could affect vegetation productivity. Analysis showed difference in temporal trends of NDVI between the reference and diversion site for the Caernarvon project with a significant increase at the diversion site although NDVI negatively responded to diversion at the beginning. Diversion did not seem to negatively affect NDVI for the Davis Pond project and NDVI only marginally increased at the diversion site. For both projects, NDVI negatively responded to water level, while salinity negatively affected NDVI or showed quadratic relation with NDVI. At the Caernarvon diversion project, the negative impact of water level on NDVI was greater at the diversion site than at the reference site. At the Davis Pond project, it was the salinity that showed different impact between the diversion and reference site. The temporal increase of NDVI at the Caernarvon diversion site can be explained by the lower salinity driven by diversion. The quadratic relation between salinity and NDVI at the Davis Pond diversion project led to only marginal increase at the diversion site. This study provided uncertainty estimates in temporal trend of NDVI and the impact of two key abiotic drivers on NDVI. The improved understanding on vegetation productivity will help predict landscape change in response to freshwater diversions.

Scale and detection method impacted Salmonella prevalence and diversity in ponds

Site-specific approaches for managing food safety hazards in agricultural water require an understanding of foodborne pathogen ecology. This study identified factors associated with Salmonella contamination in Virginia ponds. Grab samples (250mL, N=600) were collected from 30 sites across nine ponds. Culture- and culture-independent (CIDT)-based methods were used to detect Salmonella in each sample. Salmonella isolated by culture-based methods were serotyped by Kauffman-White classification. Environmental data were collected for each sample. McNemar's χ2 was used to determine if Salmonella detection differed by testing method. Separate mixed effect models were used to identify environmental factors associated with culture and CIDT-based Salmonella detection. Separate models were built for each pond, and for all ponds combined. Salmonella detection differed significantly (p<0.001) between CIDT (31%; 183/600)- and culture (13%; 77/600)-based methods. Culture-based methods yielded 11 different serovars. All cultured Salmonella samples were confirmed by CIDT; 42.1% of CIDT Salmonella-positive samples could be cultured. Associations between environmental factors and Salmonella detection also varied substantially by pond and detection method. In the all-pond model, associations were observed for five factors (total coliforms, Escherichia coli, air temperature, UV, rain) for both culture- and CIDT-based Salmonella detection. Rain prior to sampling (24h) increased odds of Salmonella detection for culture (OR=5.09) and CIDT (OR=3.62) in the all-pond model. When all the pond data were used, models masked associations at the individual pond level, as there were noticeable differences between ponds and the odds of isolating Salmonella by environmental factors. Ponds were within a 187-ha area in this study, emphasizing water management needs to be individualized (i.e., assess hazards/risks by pond). Results also highlight detection methods and scale strongly affect observed water quality and should be considered when developing monitoring programs to develop guidance for growers.

Chance and necessity in the assembly of plant communities: Stochasticity increases with size, isolation and diversity of temporary ponds

Abstract Biodiversity emerges from niche mechanisms, in which the combination of traits determines species performance, and populations drift because of the inherent stochasticity of community assembly processes. Population biology dictates that small and isolated communities are more prone to show stochastic assemblages. However, a reduced mass effect in isolated communities may promote trait selection. In addition, large and connected communities have a larger species pool, higher functional redundancy, lower population sizes and more random recruitment, which also fosters stochasticity in community assembly. These contradictory expectations demand empirical analyses. Plant metacommunities in temporary ponds are assembled by the action of strong environmental filters and cover wide ranges of local community sizes and connectivity, representing ideal systems for identifying determinants of trait‐selection processes. Using a deviance partition method introduced by the theory of community assembly by trait selection, we evaluated the role of plant traits in local community assemblies along 60 communities from a 14‐year plant survey of temporary ponds. Variation in pond size, hydroperiod, connectitivity and heterogeneity determined a selection gradien in traits related to drought resistance, life history and disperal strategies; and also in the strength of trait‐mediated community assembly. The taxonomic and functional diversity of a pond and its physical heterogeneity fostered stochasticity in the assembly of the community, which also presented a hump‐shaped association with connectivity. The pond area increased taxonomic richness but decreased functional diversity, determining negative and positive indirect effects on stochasticity. Synthesis. Diversity provides the raw material for trait selection putatively reducing stochasticity, but here diversity was positively related to stochasticity. Having enough functional diversity, larger redundancy and lower population sizes in diverse communities is probably fostering stochastic assemblages. The hump‐shaped association between stochasticity and connectivity supports a larger role of trait selection in isolated systems due to a weak mass effect, but also on connected communities in which a set of more optimal traits for the selection scenario could be available. In the ongoing state of ecosystem fragmentation, these empirical trends contribute to the mechanistic understanding of the connection between landscape structure and biodiversity assembly.

Coastal wetland area change for two freshwater diversions in the Mississippi River Delta

Coastal systems around the globe are being re-integrated with adjacent river systems to restore the natural hydrologic connection to riparian wetlands. The Mississippi River sediment diversions or river reconnections are one such tool to combat high rates of wetland loss in coastal Louisiana, USA by providing freshwater, sediment, and nutrients. There has been some disagreement in the published literature whether re-establishing river reconnection is slowing or contributing to coastal wetland loss. This issue is due to the difficulties in the application of remote sensing in low-relief environments where water level changes could indicate either land loss or simply temporary submergence. We analyzed land change at the receiving areas of two existing freshwater river diversions, Davis Pond and Caernarvon, which have been intermittently receiving river water for up to 2+ decades. This study provides a robust analysis of wetland land change rates in proximity these river diversions including years before river reconnection. Our analyses indicate a net land gain since river reconnection operations began at Davis Pond Diversion (+3.42 km 2 ; range: +2.02–4.81 km 2 ) and no statistically significant change at the Caernarvon Diversion. The Davis Pond wetland results are corroborated with data from a decadal field study documenting increased inorganic sedimentation in the soil. It is clear from this study and others, that river reconnection can increase or, in the case of Caernarvon, have no statistical effect on the land change in these systems due to differences in vegetation, hydroperiod, sediment delivery and external factors including hurricane impacts. Our remote sensing analysis was compared with a global water area change analysis mapping tool which also supported our findings.

Aquatic Plant Diversity of Ponds in Thrissur District, Kerala, India

The analysis of aquatic plant diversity was conducted in twenty ponds of Thrissur district, Kerala, during April 2014 to March 2016. During the period of study, 41 macrophytes were identified which comes under 35 genera belonging to 24 families including Pteridophytes. 46.3% of total plant species that were recorded fall into the category of marshy, followed by 19.5% submerged hydrophytes, 12.2% emergent hydrophytes, 12.2% free floating hydrophytes and 9.8% attached floating hydrophytes. The diverse plant family is Poaceae followed by Hydrocharitaceae, Onagraceae and Asteraceae.

Ecoacoustics as a novel tool for assessing pond restoration success: Results of a pilot study

Abstract Ecoacoustics is increasingly being used to monitor species populations and to estimate biodiversity in marine ecosystems, but the underwater soundscapes of freshwater environments remain largely unexplored in this respect. Few studies exist concerning the acoustic diversity of ponds, but because aquatic plants and many arthropods such as Coleoptera and Hemiptera are known to produce sound, there is potential to use ecoacoustic techniques to monitor changes in biodiversity and conservation value. This pilot study compares the underwater soundscapes of recently restored open‐canopy ponds and unmanaged highly terrestrialized ponds situated in an arable agricultural landscape of North Norfolk, UK, in order to assess the benefits of farmland pond restoration. Daytime sound recordings were made for 10 min in each pond and analysed primarily for arthropod stridulations. In addition, six commonly used acoustic indices were calculated to assess the soundscape biodiversity between the unmanaged and the restored ponds. The stridulations of three diving beetle species (Dytiscidae) were recorded in tank studies to assess the potential for individual species recognition from underwater sound capture. Sound‐type richness and abundance, as estimated by visually and aurally identifying arthropod stridulation from spectrograms, were significantly higher in the restored open‐canopy ponds compared with the unmanaged terrestrialized ponds. In addition, the acoustic indices ‘acoustic complexity’ and ‘biodiversity index’ were significantly higher in restored open‐canopy ponds than in unmanaged terrestrialized ponds. The three dytiscid water beetle species recorded in a tank were found to produce distinctive and recognizable sounds, indicating potential to create an audio reference library that could be used for automatic acoustic monitoring of freshwater arthropods. Pond soundscapes are rich in biological information and this study suggests that, with further development, automated passive ecoacoustic monitoring could be an effective non‐invasive technique for assessing pond conservation value and pond restoration and management success.

Key drivers structuring rotifer communities in ponds: insights into an agricultural landscape.

Understanding the influence of environmental and spatial factors on the structure of aquatic communities remains a major challenge in community ecology. This study aims to identify main drivers of rotifer abundance and diversity in ponds embedded in an intensive agricultural landscape in Northeast Germany. We studied 42 ponds of glacial origin (kettle holes) covering a wide range of environmental parameters. The predominant factors structuring the rotifer metacommunity shifted from abiotic environmental filtering in spring to unstudied factors in autumn, while spatial factors remained less important. Fertilizer-driven salinization, internal nutrient recycling, primary productivity and sediment phosphorus release were the prevalent biogeochemical processes in the ponds. Both fertilizer-driven salinization and primary productivity negatively affected rotifer alpha diversity, and positively affected beta diversity. This impact was lower in forest ponds than in those surrounded by arable fields or grassland. However, rotifer diversity did not significantly differ among land-use categories. Our results indicate that the long-term impact of intensive agriculture in the region and the associated widespread eutrophication overrides the direct influence of land use on rotifer diversity but point to an indirect effect via fertilizer-driven salinization. Furthermore, this study highlights the role of ponds in enhancing regional biodiversity in agricultural landscapes.

Growth rate of african catfish (Clarias gariepinus) and plankton diversity in ponds under organic and inorganic fertilization

Aquaculture offers the opportunity for safeguarding local and global food security in the face of declining capture fisheries. However, the form of aquaculture that is commonly practiced in Kenya is characterized by the use of agrochemicals such as fertilizers that negatively impact biodiversity especially when effluents from fish ponds drain into water bodies. This study aimed to determine differences in the growth rate of Clarias gariepinus, an important aquaculture fish in Kenya, to assess plankton diversity, and to identify phytoplankton species associated with pollution under organic and inorganic fertilization regimens using chicken manure, Diammonium phosphate, and urea, respectively. Average growth rate calculated per day was higher in the organically-fertilized ponds at 0.06 cm/day, followed by inorganically-fertilized ponds at 0.05cm/day and then, the control at 0.04 cm/day. Average weight gain was higher in organically-fertilized ponds at 0.08 g/day followed by ponds fertilized with inorganic fertilizer at 0.07 g/day and the control, at 0.06g/day. There were significant differences in growth rate across fertilization regimens (length: F2, 264= 24.06, p = 0.0399; weight: F2, 264 = 20.89, p = 0. 0457). Specifically, although differences in growth rate of fish in organically and inorganically fertilized ponds were not significant, fish in fertilized ponds were on average, longer and weighed more than those in the control pond. Jaccard’s similarity index for phytoplankton was highest (0.38) between organically-fertilized ponds and control but lowest (0.25) between inorganically-fertilized ponds and control. Use of chicken manure produced the highest diversity of zooplankton (Shannon-Weiner’s H in organically-fertilized pond = 1.886; inorganic = 1.044, and control = 0.935). The use of DAP and urea produced the highest proportion of phytoplankton species associated with pollution. These results do not support the commonly reported notion that ponds fertilized using inorganic fertilizers are more productive. Findings suggest that the use of inorganic fertilizers may threaten biodiversity in aquatic ecosystems through the production of toxic algae.

Dynamic Energy Budget modelling to predict eastern oyster growth, reproduction, and mortality under river management and climate change scenarios

Eastern oysters growing in deltaic Louisiana estuaries in the northern Gulf of Mexico must tolerate considerable salinity variation from natural climate variability (e.g., rainfall and stream run-off pushing isohalines offshore; tropical storms pushing isohalines inshore) and man-made diversions and siphons releasing freshwater from the Mississippi River. These salinity variations are predicted to increase with future climate change because of the increased frequency of stronger storms and also in response to proposed large-scale river diversions. Increased Mississippi River flow into coastal estuaries from river diversions, along with potential changes in rainfall and stream run-off from climate change will alter spatial and temporal salinity patterns. In this study we used an individual Dynamic Energy Budget model to predict growth and reproductive potential of eastern oysters across observed and simulated salinity gradients corresponding to different climate and river management scenarios. We used validated model outputs of salinity from a coupled hydrology-hydrodynamic model to assess the current impacts of Davis Pond diversion discharge on oysters located downstream. Under a high diversion discharge scenario oyster growth potential was reduced by 9%, 4%, and 1% in Upper, Mid, and Lower Bay locations, respectively, as compared to a limited discharge year. Reproductive outputs decreased by 34% and 2% in the Upper and Lower Bay locations, respectively, and increased by 2% at the Mid Bay site. In scenarios combining predicted increased temperature with the effect of diversions, all oysters located in the Upper and Mid Bay sites died due to severe summer conditions (high temperatures combined with low salinity). Overall, oysters in down-estuary locations, influenced by both estuarine river management and gulf conditions demonstrated significant tolerance to changing salinity and temperature conditions from diversions alone and when combined with climate change. In contrast, oysters located up-estuary, and exposed to more extreme salinity impacts from river management, demonstrated potentially lethal impacts through direct mortality, and reduced sustainability through decrease in reproductive output. These predictions at the individual level may translate into less sustainable populations in the most extreme scenarios; restoration and production plans may benefit from accounting for these impacts on reproductive output particularly as decision makers seek to restore critical oyster areas.

Anuran diversity in ponds associated with soybean plantations.

Anurans are considered one of the most threatened animal groups in the world. Agricultural activities are related to water pollution and contamination, which affects biphasic organisms such as amphibians. Brazilian soybean cultivation covers about 36 million hectares and encompasses many remaining ponds used as breeding sites for amphibians. In this study, we evaluated richness, abundance and composition of the anuran communities in ponds with different levels of association with soybean cultivation. A total of 18 anuran species were recorded with an abundance of 421 collected tadpoles and 1230 adult males on average. Ponds presented in soybean plantations were distinct from those adjacent to plantations regarding water properties and tadpole richness and abundance, as well as composition of tadpoles and adults. Ponds inserted in plantations had communities with lower diversity and abundance. One explanation for these results is likely the detrimental effect of soybean management, which suggests that this decrease is a result of community changes. This serves as an alert about the importance of buffer areas around plantations and the use of adequate techniques for pesticide application.

Assessing the impact of the threatened crucian carp (Carassius carassius) on pond invertebrate diversity: A comparison of conventional and molecular tools.

Fishes stocked for recreation and angling can damage freshwater habitats and negatively impact biodiversity. The pond-associated crucian carp (Carassius carassius) is rare across Europe and is stocked for conservation management in England, but its impacts on pond biota are understudied. Freshwater invertebrates contribute substantially to aquatic biodiversity, encompassing many rare and endemic species, but their small size and high abundance complicate their assessment. Practitioners have employed sweep-netting and kick-sampling with microscopy (morphotaxonomy), but specimen size/quality and experience can bias identification. DNA and environmental DNA (eDNA) metabarcoding offer alternative means of invertebrate assessment. We compared invertebrate diversity in ponds (N=18) with and without crucian carp using morphotaxonomic identification, DNA metabarcoding and eDNA metabarcoding. Five 2 L water samples and 3 min sweep-net samples were collected at each pond. Inventories produced by morphotaxonomic identification of netted samples, DNA metabarcoding of bulk tissue samples and eDNA metabarcoding of water samples were compared. Alpha diversity was greatest with DNA or eDNA metabarcoding, depending on whether standard or unbiased methods were considered. DNA metabarcoding reflected morphotaxonomic identification, whereas eDNA metabarcoding produced markedly different communities. These complementary tools should be combined for comprehensive invertebrate assessment. Crucian carp presence minimally reduced alpha diversity in ponds, but positively influenced beta diversity through taxon turnover (i.e., ponds with crucian carp contained different invertebrates to fishless ponds). Crucian carp presence contributes to landscape-scale invertebrate diversity, supporting continued conservation management in England. Our results show that molecular tools can enhance freshwater invertebrate assessment and facilitate development of more accurate and ecologically effective pond management strategies.

Density Dynamics and Plankton Diversity in Pond with Different Bases at Faculty of Fisheries and Marine Education Pond

The availability of plankton in the waters is influenced by nutrient content, and the waters physics-chemical conditions. The higher the nutrient content in a waters, the higher phytoplankton abundance in the waters will be.This research is conducted at faculty of fisheries and marine education pond Airlangga University. It is aimed to density dynamics and plankton diversity in pond with different bases. This research method uses survey method.The reseach results shows that the highest density in tarpaulin pond is located at point four on the first day that reaches 1,822,000 ind/l, The highest total density on the ground pools is got on first day on the first point of 245,000 ind/l.

Comparative Study on Phytoplankton Community in Two Newly Dug Ponds in Institut Teknologi Sumatera

Phytoplankton community plays an important ecological role in the aquatic ecosystems as the primary producers and forms the fundament of the aquatic food chain for supporting the water community. Thus, the phytoplankton community structure is a good indicator of water quality due to its sensitiveness to environmental stresses. Two newly dug ponds in Institut Teknologi Sumatera may give an opportunity to study the early colonizing stages of various freshwater communities including phytoplankton. The study attempted to determine the composition and abundance of phytoplankton. Samples were collected from two ponds (A and C) in the reservoir water of Institut Teknologi Sumatera. The content of Phosphorus (P), Nitrogen (N), and Chlorophyll-a (algae biomass) were determined. Phytoplankton had higher diversity in Pond C than Pond A in the study period, in which a total of seven taxa were found, namely Bacillariophycea, Cyanophyceae, Chlorophyceae, Conjugatophyceae, Dinophyceae, Euglenophyceae, Gymnodiniaceae. The most species abundance of both ponds was Peridinium sp. and Trachelomonas sp. The Pond C had the highest mean value of the Shannon-Wiener diversity index. The Linear mixed-effect model showed that low turbidity will result in high phytoplankton diversity. The finding of this study suggests that higher phytoplankton diversity would achieve a natural carrying capacity, and thus would serves as an indicator of ecosystem health.

Spatial and temporal changes to a hydrologically-reconnected coastal wetland: Implications for restoration

Abstract Mississippi River Delta wetlands were isolated from river influence due to levee construction beginning in the early 1900's. Surface water diversions were primarily designed to manage salinity and maintain marsh vegetation by reintroducing Mississippi River water and nutrients into adjacent wetlands. Phosphorus (P) is a major limiting nutrient that can control productivity, but in excess can contribute to wetland eutrophic conditions and water quality degradation. Most wetland soil characterization assessments consider soil total P, however, this parameter alone cannot describe P bioavailability due to differences in organic and inorganic forms. A soil characterization of the Davis Pond diversion was done in 2007, before full-scale operation began, and in 2018 after 11 years of river loading. The top 10 cm of soil from 140 stations each year were analyzed for physiochemical properties and both organic and inorganic P forms. Mineral content is used to delineate areas of river diversion influence and compare P stocks between hydrologically isolated marsh areas and where effective river diversion reconnection took place. The river diversion resulted in a nearly 100% increase in soil mineral content and 58% increase in bulk density. The dominant source of soil P has changed from organic P to inorganic P in 29% of the wetland area, significantly associated with mineral content of the soil. Inorganic P stocks in diversion influenced areas are 9 times higher than those which remained isolated from riverine materials. The study demonstrates that long-term addition of mineral sediments and inorganic P did not lead to deleterious effects in the wetland soil. This is the first study in the Mississippi River delta to spatially track river reconnection driven wetland P dynamics and can provide valuable information for predictive models for sediment diversions for coastal restoration.

Environmental heterogeneity drives macrophyte beta diversity patterns in permanent and temporary ponds in an agricultural landscape

Understanding patterns of beta diversity (heterogeneity) and its components (substitution and subset) is important for managing freshwater ecosystems and the research on these topics has increased over the last decade. However, there has been limited empirical research exploring the drivers of these components of beta diversity in ponds from agricultural landscapes, in which hydroperiod length is often a key structural driver. The purpose of our work was to examine the contribution of substitution (species replacement among sites without changes in richness) and subset (species differences among sites when species-poor sites constitute subsets of those with a greater number of taxa) structuring processes on macrophyte beta diversity patterns of sixteen permanent and ten temporary Mediterranean ponds. We also aimed to test the structuring role of local environmental factors and geographic isolation and to determine whether there are differences in the community heterogeneity and the relative importance of the substitution and subset fractions of beta diversity between permanent and temporary ponds. We found that temporary ponds were environmentally and biologically less heterogeneous and supported lower richness than permanent waterbodies. In both pond types, beta diversity almost entirely reflected patterns of species substitution rather than subsets. Local environmental conditions, and not among-pond distance, were the main drivers of macrophyte community structure. Overall, our results suggest that local environmental variables operating through niche processes were the primary mechanisms driving macrophyte beta diversity patterns, thus highlighting the importance of environmental heterogeneity for maintaining pond community diversity in agricultural landscapes. Accordingly, conservation initiatives and ecosystem management strategies should include permanent and temporary pond clusters comprising wide environmental gradients in their efforts to ensure high levels of regional biodiversity.

Wetland Plant Community Responses to the Interactive Effects of Simulated Nutrient and Sediment Loading: Implications for Coastal Restoration Using Mississippi River Diversions

The Mississippi River Delta Complex (MRDC) has experienced extensive wetland loss in the last century due, in part, to flood control levees that have isolated the lower Mississippi River and its sediment resource from adjacent wetlands. Reconnecting the River to these wetlands through diversions is being used and proposed on a larger scale for the future, to reduce wetland loss rates. However, some currently operating diversions (e.g., Caernarvon and Davis Pond) have been implicated in causing negative impacts on wetland ecosystem structure and function due to increased nutrient loads in diverted Mississippi River water combined with insufficient sediment delivery. Initial assessments of these concerns were carried out in a greenhouse setting where six nutrient enrichment treatment levels (control, NO3, NH4, PO4, SO4, and Combo [NO3 + NH4 + PO4 + SO4]) were applied with and without sediment addition to 60 marsh sods from a Sagittaria lancifolia-dominated oligohaline wetland at rates simulating the Davis Pond Diversion of the Mississippi River. After 25 months, independent enrichment with N (regardless of form) and sediment was generally beneficial to wetland structure and function, while SO4 enrichment had the opposite effect, regardless of sediment addition. Simultaneous application of N and P (i.e., the Combo treatment level) ameliorated the negative impacts of SO4-loading, but the concurrent application of sediment did not, likely because the loading rate was based on a diversion that was designed to deliver water and not to maximize sediment input. Nonetheless, sediment input is critical to the sustainability of MRDC wetlands experiencing high rates of deterioration. Thus, optimizing future diversions to maximize sediment delivery, along with continued surveillance of negative nutrient effects, are recommended management decisions.

Effect of Physico-chemical Factors and Plankton Abundance in Selected Tropical Fish Earthen Ponds' Water

The study investigated the plankton diversity and abundance of three selected on-farm research fish ponds in Nigerian Institute for Oceanography and Marine Research, Lagos. Samples were taken from three ponds using standard procedure and physico- chemical features of the water bodies were measured. Plankton of class ( Bacillariophyceae, Chlorophyceae, Cyanophyceae and Euglenophyceae I) and Zooplanktons of ( Cladocera, Rotifera and Copepoda ) family were found. There were varying results for the phytoplaktons and zooplaktons respectively during the study. The highest percentage composition for phytoplankton was recorded in Pond 1 (94.11%), and the highest Shannon-Weaner diversity (1.265%) in pond 2. The highest percentage of zooplankton was recorded in pond 2 (91.67%). Utilizing the parameter of Shannon index value, the abundance value for zooplaktons was not remarkable. Statistical association between parameters and abundance reflected that abundance was positively correlated with temperature, and negatively correlated with pH while the levels of dissolved oxygen (DO) were positively correlated. The low densities and plankton diversity in pond 3 was an indication of low pH and high transparency as a result of nutrient depletion. Keywords : Abundance; physico-chemical factors; phytoplankton; zooplankton; fish ponds

Linking environmental drivers with amphibian species diversity in ponds from subtropical grasslands.

Amphibian distribution patterns are known to be influenced by habitat diversity at breeding sites. Thus, breeding sites variability and how such variability influences anuran diversity is important. Here, we examine which characteristics at breeding sites are most influential on anuran diversity in grasslands associated with Araucaria forest, southern Brazil, especially in places at risk due to anthropic activities. We evaluate the associations between habitat heterogeneity and anuran species diversity in nine body of water from September 2008 to March 2010, in 12 field campaigns in which 16 species of anurans were found. Of the seven habitat descriptors we examined, water depth, pond surface area and distance to the nearest forest fragment explained 81% of total species diversity. Water depth, margin vegetation type, surface area and distance to the next body of water explained between 31-74% of the variance in abundance of nine of the 16 species. Thus, maintenance of body of water, of the vegetation along the water edge and natural forest fragments in the grasslands, along with fire control (used to renovation of pasture), are fundamentally important for the maintenance of anuran species diversity through the conservation of their breeding sites.