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Publisher: Springer-Verlag   (Total: 2335 journals)

 Aquatic Ecology   [SJR: 0.646]   [H-I: 44]   [31 followers]  Follow         Hybrid journal (It can contain Open Access articles)    ISSN (Print) 1573-5125 - ISSN (Online) 1386-2588    Published by Springer-Verlag  [2335 journals]
• Rare but large bivalves alter benthic respiration and nutrient recycling
in riverine sediments
• Authors: Sara Benelli; Marco Bartoli; Erica Racchetti; Paula Carpintero Moraes; Mindaugas Zilius; Irma Lubiene; Elisa Anna Fano
Pages: 1 - 16
Abstract: Bioturbation studies have generally analyzed small and abundant organisms while the contribution to the benthic metabolism by rare, large macrofauna has received little attention. We hypothesize that large, sporadic bivalves may represent a hot spot for benthic processes due to a combination of direct and indirect effects as their metabolic and bioturbation activities. Intact riverine sediments with and without individuals of the bivalve Sinanodonta woodiana were collected in a reach with transparent water, where the occurrence of the mollusk was clearly visible. The bivalve metabolism and its effects on sedimentary fluxes of dissolved gas and nutrients were measured via laboratory incubations of intact cores under controlled conditions. S. woodiana contributed significantly to O2 and TCO2 benthic fluxes through its respiration and to $${\text{NH}}_{4}^{ + }$$ , SRP and SiO2 regeneration via its excretion. The bivalve significantly stimulated also microbial denitrification and determined a large efflux of CH4, likely due a combination of bioturbation and biodeposition activities or to anaerobic metabolism within the mollusk gut. This study demonstrates that a few, large individuals of this bivalve produce significant effects on aerobic and anaerobic benthic metabolism and nutrient mobilization. Random sediment sampling in turbid waters seldom catches these important effects due to low densities of large fauna.
PubDate: 2017-03-01
DOI: 10.1007/s10452-016-9590-3
Issue No: Vol. 51, No. 1 (2017)

• Distribution and microhabitat associations of the juveniles of a
high-value sea cucumber, Stichopus cf. horrens, in northern Philippines
• Authors: N. Palomar-Abesamis; R. A. Abesamis; M. A. Juinio-Meñez
Pages: 17 - 31
Abstract: There is considerable global interest in rebuilding depleted populations of sea cucumbers (Echinodermata, Holothuroidea) to address conservation and economic goals. For the vast majority of holothurian species, the habitat and food requirements of the juvenile stage are poorly understood. We investigated the distribution and microhabitat associations of juveniles of a commercially important sea cucumber, Stichopus cf. horrens, in the shallow, shoreward side of a coral reef (or backreef) in northern Philippines (16°21′38.7″N, 119°59′47.9″E). Relationships between juvenile density and the physical, chemical and biological characteristics of their habitat were examined. Potential food sources of the juveniles were also investigated using elemental and stable isotope analysis. Results showed that juveniles are more abundant in seagrass areas and the transition zone between seagrass and the rubble-dominated reef flat. A non-metric multidimensional scaling (MDS) plot indicated that juvenile density was most positively associated with coarser sand and rubble (>0.5 mm) and seagrass (Thalassia hemprichii) abundance (2D stress = 0.11). Juvenile density was also positively associated with sediment organic matter from plant detritus to a lesser extent. Elemental and isotope analysis of one site indicated that epiphytes were the primary food source of juveniles, while sediment detritus from microalgae and seagrass was a secondary food source. This study corroborates anecdotal evidence regarding the importance of seagrass to S. cf. horrens as potential refugia and source of high-quality food for its juveniles. These findings underscore the need to protect the nursery habitats of wild juveniles and provide critical information for the selection of suitable natural habitats for releasing cultured juveniles of this important species.
PubDate: 2017-03-01
DOI: 10.1007/s10452-016-9591-2
Issue No: Vol. 51, No. 1 (2017)

• Effects of temperature and food quality on isotopic turnover and
• Authors: Hélène Masclaux; Nicole B. Richoux
Pages: 33 - 44
Abstract: Our experimental study was designed to assess the effects of temperature on nitrogen isotope turnover and to measure the effects of temperature and food quality on the stable carbon and nitrogen isotope discrimination factors (Δ13C and Δ15N) in a cladoceran. For the first part of our study, Daphnia were fed with non-enriched or 15N-enriched Scenedesmus obliquus at 12, 15, 20, and 25 °C. For the second part, Daphnia were reared at 15, 20, and 25 °C on Scenedesmus or Cryptomonas sp. There were no clear effects of temperature on turnover rates of the nitrogen isotope of cladocerans. However, a general increase in Δ13C with increasing temperature was measured, regardless of the food source. Δ15N was also affected by temperature, but contrasting results were measured depending on the food source used. There were significant effects of food quality on Δ13C and Δ15N in Daphnia, as values obtained for Daphnia fed Scenedesmus were always higher than those obtained for Daphnia fed Cryptomonas. Our experiments produced discrimination factors that were very different from those usually considered in isotope studies and showed that the values used for isotope model implementation to analyze field data need to be adapted to environmental conditions.
PubDate: 2017-03-01
DOI: 10.1007/s10452-016-9592-1
Issue No: Vol. 51, No. 1 (2017)

• Metacommunity dynamics of amphibians in years with differing rainfall
• Authors: Attila L. Péntek; Csaba F. Vad; Katalin Zsuga; Zsófia Horváth
Pages: 45 - 57
Abstract: Many studies investigated the habitat preference and behaviour ecology of individual amphibian species while we know less about how their community assembly reflects changes in environmental factors, including the role of climatic extremes. Community-level studies also allow us to apply trait-based analyses that are crucial for a better understanding of the functioning of amphibian communities and metacommunities. In two years with contrasting rainfall (2012 and 2013), we found amphibian species in 85 different waterbodies of a heterogeneous landscape in Central Europe (Hungary). Within the metacommunity framework, the contributions of local, landscape and spatial variables to community assembly were assessed. We also measured the local extinction–colonisation rates in the ponds for all species between the two years. To investigate the role of dispersal traits in explaining the spatial distribution of species, we studied the relationship between body size and the pure spatial fraction of variation. According to our results, the main drivers were the same in both the dry and wet year, but their relative contribution changed. Local variables played a predominant role in the assembly of the amphibian metacommunity. Spatial signals were more evident in the dry year. This implies not only the adverse effect of decreased connectivity due to the drying out of several habitats but also a loss of breeding sites for the studied amphibians. Local colonisation rates were higher in primarily terrestrial species (Hyla arborea, Pelobates fuscus, Bufo bufo) which only visit ponds during breeding. We found a negative relationship between the pure spatial effect and body size, suggesting an increased level of dispersal limitation in small-bodied species. Our results showed that while the strength and relative role of local and spatial processes changed between years, the role of dispersal traits in explaining the spatial distribution of species was similar. Specialisation to different habitats seems to be a major process in determining vertebrate metacommunities in landscapes. Dispersal traits of different species should be taken more into consideration in the practical conservation of amphibian habitats.
PubDate: 2017-03-01
DOI: 10.1007/s10452-016-9597-9
Issue No: Vol. 51, No. 1 (2017)

• Elevated carbon dioxide has the potential to impact alarm cue responses in
some freshwater fishes
• Authors: John A. Tix; Caleb T. Hasler; Cody Sullivan; Jennifer D. Jeffrey; Cory D. Suski
Pages: 59 - 72
Abstract: Freshwater fish behaviors have the potential to be impacted by acidification due to increases in dissolved carbon dioxide (CO2). Recent work in the marine environment suggests that increased CO2 levels due to climate change can negatively affect fishes homing to natal environments, while also hindering their ability to detect predators and perform aerobically. The potential for elevated CO2 to have similar negative impacts on freshwater communities remains understudied. The objective of our study was to quantify the effects of elevated CO2 on the behaviors of fathead minnows (Pimephales promelas) and silver carp (Hypophthalmichthys molitrix) following exposure to conspecific skin extracts (alarm cues). In fathead minnows, their response to conspecific skin extracts was significantly impaired following exposure to elevated CO2 levels for at least 96 h, while silver carp behaviors were unaltered. However, fathead minnow behaviors did return to pre-CO2 exposure in high-CO2-exposed fish following 14 days of holding at ambient CO2 levels. Overall, this study suggests there may be potential impacts to freshwater fishes alarm cue behaviors following CO2 exposure, but these responses may be species-specific and will likely be abated should the CO2 stressor be removed.
PubDate: 2017-03-01
DOI: 10.1007/s10452-016-9598-8
Issue No: Vol. 51, No. 1 (2017)

• Groundwater biodiversity in a chemoautotrophic cave ecosystem: how
geochemistry regulates microcrustacean community structure
• Authors: Diana M. P. Galassi; Barbara Fiasca; Tiziana Di Lorenzo; Alessandro Montanari; Silvano Porfirio; Simone Fattorini
Pages: 75 - 90
Abstract: The Frasassi cave system in central Italy hosts one of the few known examples of a groundwater metazoan community that is supported by sulfur-based lithoautotrophic microbes. Despite the challenging conditions represented by high concentrations of H2S and low concentrations of O2, this cave system is home to many invertebrate species. Here, we analyzed the copepods inhabiting sulfidic lakes and non-sulfidic dripping pools in order to investigate how environmental conditions in sulfidic waters regulate the spatial distribution of the cave microcrustacean community over time. We also sampled copepod assemblages of sulfidic lakes under conditions of both high and low H2S concentration. Cluster analysis and canonical correspondence analysis separated the copepod assemblages inhabiting dripping pools from those of sulfidic lakes. H2S concentration, pH and O2 concentration were identified as the main factors regulating community structure. These results indicate that the distribution of groundwater copepods within the cave system is ecologically and spatially structured. Sulfidic lakes showed lower Simpson dominance, higher Shannon diversity and higher Pielou equitability at higher H2S concentrations. The complex community structure of the copepods of the Frasassi cave system suggests that a chemosynthetically produced food source facilitated the colonization of stygobionts in sulfidic groundwater due to their tolerance to the environmental conditions.
PubDate: 2017-03-01
DOI: 10.1007/s10452-016-9599-7
Issue No: Vol. 51, No. 1 (2017)

• Short-term interactive effects of ultraviolet radiation, carbon dioxide
and nutrient enrichment on phytoplankton in a shallow coastal lagoon
• Authors: Rita B. Domingues; Cátia C. Guerra; Helena M. Galvão; Vanda Brotas; Ana B. Barbosa
Pages: 91 - 105
Abstract: The main goal of this study was to evaluate short-term interactions between increased CO2, UVR and inorganic macronutrients (N, P and Si) on summer phytoplankton assemblages in the Ria Formosa coastal lagoon (SW Iberia), subjected to intense anthropogenic pressures and highly vulnerable to climate change. A multifactorial experiment using 20 different nutrient-enriched microcosms exposed to different spectral and CO2 conditions was designed. Before and after a 24-h in situ incubation, phytoplankton abundance and composition were analysed. Impacts and interactive effects of high CO2, UVR and nutrients varied among different functional groups. Increased UVR had negative effects on diatoms and cyanobacteria and positive effects on cryptophytes, whereas increased CO2 inhibited cyanobacteria but increased cryptophyte growth. A positive synergistic interaction between CO2 and UVR was observed for diatoms; high CO2 counteracted the negative effects of UVR under ambient nutrient concentrations. Nutrient enrichments suppressed the negative effects of high CO2 and UVR on cyanobacteria and diatoms, respectively. Beneficial effects of CO2 were observed for diatoms and cryptophytes under combined additions of nitrate and ammonium, suggesting that growth may be limited by DIC availability when the primary limitation by nitrogen is alleviated. Beneficial effects of high CO2 and UVR in diatoms were also induced or intensified by ammonium additions.
PubDate: 2017-03-01
DOI: 10.1007/s10452-016-9601-4
Issue No: Vol. 51, No. 1 (2017)

• The ecological adaptability of Phragmites australis to interactive effects
of water level and salt stress in the Yellow River Delta
• Authors: Bo Guan; Junbao Yu; Aixin Hou; Guangxuan Han; Guangmei Wang; Fanzhu Qu; Jiangbao Xia; Xuehong Wang
Pages: 107 - 116
Abstract: Soil salinity and waterlogging are two major environmental problems in estuarine wetlands. To prevent the typical wetland plants from degradation by soil salinization and salt waterlogging and more effectively use the plants to provide wetland ecosystem services, we examined the ecological adaptability of Phragmites australis, a characteristic plant species in the Yellow River Delta, to the interactive effects of water level and salt stress. The results showed that P. australis adapts to salt and water table stressed environments through slowing down the growth rate, maintaining the tiller number, and adjusting the biomass allocation of different organs. The highest plant height and the largest leaf area were at 0 cm water table treatment; the 0.5 % NaCl treatment increased the aboveground biomass; higher water table increased the fibrous root biomass allocation, but largely decreased the leaf biomass. The exclusion of toxic inorganic ions such as Na+ and Cl− and the accumulation of organic solutes are also important mechanisms to aid survival in saline wetlands. On average 35.1 % of Cl− and 53.9 % of Na+ accumulated in belowground organs. The study could provide fundamental guidance for wetland restoration projects and wetland sustainable use in coastal zones such as the Yellow River Delta.
PubDate: 2017-03-01
DOI: 10.1007/s10452-016-9602-3
Issue No: Vol. 51, No. 1 (2017)

• Competition between a toxic and a non-toxic Microcystis strain under
constant and pulsed nitrogen and phosphorus supply
• Authors: Saara Suominen; Verena S. Brauer; Anne Rantala-Ylinen; Kaarina Sivonen; Teppo Hiltunen
Pages: 117 - 130
Abstract: The toxicity of a harmful algal bloom is strongly determined by the relative abundance of non-toxic and toxic genotypes and might therefore be regulated by competition for growth-limiting resources. Here, we studied how the toxic Microcystis aeruginosa strain PCC 7806 and a non-toxic mutant compete for nitrogen and phosphorus under constant and pulsed nutrient supply. Our monoculture and competition experiments show that these closely related genotypes have distinct nutrient physiologies and that they differ in their ability to compete for nitrogen and phosphorus. The toxic wild type won the competition under nitrogen limitation, while the non-toxic mutant dominated under phosphorus limitation. Pulses of both nitrogen and phosphorus increased the dominance of the toxic genotype, which lead to an even faster competitive exclusion of the non-toxic genotype under nitrogen pulses and to coexistence of both genotypes under phosphorus pulses. Our findings indicate that the genotype level dynamics driven by resource competition can be an important factor in determining cyanobacterial bloom toxicity.
PubDate: 2017-03-01
DOI: 10.1007/s10452-016-9603-2
Issue No: Vol. 51, No. 1 (2017)

• Response variable selection in principal response curves using permutation
testing
• Authors: Nadia J. Vendrig; Lia Hemerik; Cajo J. F. ter Braak
Pages: 131 - 143
Abstract: Principal response curves analysis (PRC) is widely applied to experimental multivariate longitudinal data for the study of time-dependent treatment effects on the multiple outcomes or response variables (RVs). Often, not all of the RVs included in such a study are affected by the treatment and RV-selection can be used to identify those RVs and so give a better estimate of the principal response. We propose four backward selection approaches, based on permutation testing, that differ in whether coefficient size is used or not in ranking the RVs. These methods are expected to give a more robust result than the use of a straightforward cut-off value for coefficient size. Performance of all methods is demonstrated in a simulation study using realistic data. The permutation testing approach that uses information on coefficient size of RVs speeds up the algorithm without affecting its performance. This most successful permutation testing approach removes roughly 95 % of the RVs that are unaffected by the treatment irrespective of the characteristics of the data set and, in the simulations, correctly identifies up to 97 % of RVs affected by the treatment.
PubDate: 2017-03-01
DOI: 10.1007/s10452-016-9604-1
Issue No: Vol. 51, No. 1 (2017)

• Coexisting small fish species in lotic neotropical environments: evidence
of trophic niche differentiation
• Authors: Jislaine Cristina da Silva; Éder André Gubiani; Mayara Pereira Neves; Rosilene Luciana Delariva
Abstract: Differences among species and their ecological requirements are considered fundamental in determining the outcome of species interactions as well as in coexistence. Thus, species that co-occurs tends to differ in the use of resources as a way to mitigate the effects of interspecific competition, facilitating interactions between pairs of species. So, this study used a set of seven small-sized characid species with similar morphology and feeding strategies, in order to investigate the hypothesis that the coexistence these species is facilitated by the differential use of food resources. Samplings were conducted in the rivers Verde and São Domingos, Upper Paraná River basin, Brazil, in hydrological periods rainy and dry. The analysis of 1055 stomach contents, by the volumetric method, indicated that the species consumed mainly allochthonous items, such as seeds, terrestrial plants and insects. In addition, they showed inter- and intraspecific differences in the diet composition between hydrological periods, which allowed the identification of items that particularise each species and contribute to the trophic segregation between them. Despite the wide variety of food items used, it was not possible to observe a consistent pattern of widening or narrowing of the food spectrum between hydrological periods, as expected. The trophic niche overlap showed intermediate and low values in both periods. In this sense, resource partitioning among species of small characids, facilitated by exploitation of different preferential resources as well as the intraspecific variation in response to seasonal availability of resources, became evident. The alternation of items and proportions of items in the diet as well as changes in feeding behaviour in opportune moments was probably the key for the coexistence of these species.
PubDate: 2017-03-17
DOI: 10.1007/s10452-017-9616-5

• Effects of nutrient and water level changes on the composition and size
structure of zooplankton communities in shallow lakes under different
climatic conditions: a pan-European mesocosm experiment
• Authors: Ülkü Nihan Tavşanoğlu; Michal Šorf; Konstantinos Stefanidis; Sandra Brucet; Semra Türkan; Helen Agasild; Didier L. Baho; Ulrike Scharfenberger; Josef Hejzlar; Eva Papastergiadou; Rita Adrian; David G. Angeler; Priit Zingel; Ayşe İdil Çakıroğlu; Arda Özen; Stina Drakare; Martin Søndergaard; Erik Jeppesen; Meryem Beklioğlu
Abstract: Lentic ecosystems act as sentinels of climate change, and evidence exists that their sensitivity to warming varies along a latitudinal gradient. We assessed the effects of nutrient and water level variability on zooplankton community composition, taxonomic diversity and size structure in different climate zones by running a standardised controlled 6-months (May to November) experiment in six countries along a European north–south latitudinal temperature gradient. The mesocosms were established with two different depths and nutrient levels. We took monthly zooplankton samples during the study period and pooled a subsample from each sampling to obtain one composite sample per mesocosm. We found a significant effect of temperature on the community composition and size structure of the zooplankton, whereas no effects of water depth or nutrient availability could be traced. The normalised size spectrum became flatter with increasing temperature reflecting higher zooplankton size diversity due to higher abundance of calanoid copepods, but did not differ among depths or nutrient levels. Large-bodied cladocerans such as Daphnia decreased with temperature. Taxonomic diversity was positively related to size diversity, but neither of the two diversity measures demonstrated a clear pattern along the temperature gradient nor with nutrient and water levels. However, genus richness decreased at the warm side of the temperature gradient. Our experiment generally supports recent empirically based findings that a continuing temperature increase may result in lower genus richness and lower abundance of large-sized zooplankton grazers, the latter likely resulting in reduced control of phytoplankton.
PubDate: 2017-02-28
DOI: 10.1007/s10452-017-9615-6

• Helminth parasite assemblages in two cyprinids with different life history
strategies
• Authors: Brandon P. Ruehle; Kristin K. Herrmann; Christopher L. Higgins
Abstract: Parasitic organisms can affect ecosystems by driving population dynamics of the hosts and influencing community interactions. The life history of the host can determine the relationship with its parasites. Reproductive effort and age of the host are two life history aspects often used to explain parasitic infection. In this study, we examined helminth parasite assemblages in two cyprinids with contrasting reproductive strategies, Cyprinella venusta (crevice spawners) and Notropis volucellus (broadcast spawners), in the Paluxy River (Texas) from May 2014 through October 2015. Host reproduction was measured using the gonadosomatic index, and standard length was used as an estimate of age. Parasite infection was measured using total number of helminths, parasite richness, Shannon’s diversity, and Simpson’s diversity. Our results revealed significant differences in parasite number and diversity between the two species, but not between males and females within species. Additionally, our results showed that standard length was a better predictor of parasitic infection than the gonadosomatic index. The relationship between host size and parasitic infection was expected; however, the lack of a relationship between gonadosomatic indices and parasitic infection was surprising. In conclusion, standard length was a better predictor of parasitic infection than the gonadosomatic index, and as such multiple species and life history traits should be considered when investigating host–parasite relationships.
PubDate: 2017-01-28
DOI: 10.1007/s10452-017-9614-7

• Benefits of adjacent habitat patches to the distribution of a crayfish
population in a hydro-dynamic wetland landscape
• Authors: Craig A. van der Heiden; Nathan J. Dorn
Abstract: Aquatic macrophyte patches are natural features of wetland ecosystems that serve as habitat for aquatic animals. Previous studies suggest animal densities in Everglades, USA, wetlands are generally less numerous in sawgrass ridges than in deeper lily sloughs. We studied the density distribution of a population of Procambarus fallax in ridge and slough habitat types over a 2-year period, spanning two wet–dry cycles and estimated growth and survival rates under flooded conditions to understand comparative value of each to the crayfish population. Procambarus fallax individuals inhabited and recruited in both marsh habitats. During periods of high water, crayfish densities were similar in both habitats; however, densities in both habitats varied seasonally, leading us to postulate some degree of population redistribution in response to fluctuating water depths. Analysis of size distributions over time revealed juveniles in both habitats and two major recruitment periods each year; distinct juvenile cohorts were present in early winter (Nov–Dec) and mid-summer (July–Aug). An in situ experiment of juvenile growth demonstrated that slough habitat type supported faster growth over ridge habitat. To understand habitat-specific mortality risk, a tethering study during flooded conditions indicated that relative predation risk by aquatic predators was greater in sloughs for all sizes and higher for smaller individuals in both habitats. The comparative importance of ridge and slough balances growth potential and survival probability during flooded conditions. This is the first study through time and across both habitat types analyzing the distribution and size structure of P. fallax population in the Everglades.
PubDate: 2017-01-09
DOI: 10.1007/s10452-016-9612-1

• Wind differentiates reproduction in the non-expansive Black Tern
Chlidonias niger and the expansive White-winged Tern Chlidonias
leucopterus
• Authors: Artur Golawski; Zbigniew Kasprzykowski; Emilia Mroz
Abstract: Identifying the key factors governing the expansion of a species’ range is difficult because of the multiple interactions of environmental and biological factors. Among the biological factors are breeding parameters, which at the edge of a species’ range may indicate the traits involved in limiting species distribution. To evaluate whether the hatching success of two sympatric species of terns was dependent on weather parameters, a study was carried out in the valley of the River Bug in eastern Poland. During 2007–2010, nine colonies with 113 clutches of White-winged Tern (CHL, an expansive species, new to the region since 1997) and 92 clutches of Black Tern (CHN, a non-expansive species, nesting in stable numbers in this region for many years) were monitored. CHN arrived on average 9 days earlier than CHL. While CHN arrived in east-central Poland earlier and earlier during the 1998–2013 period, no such trend was recorded for CHL. The clutch initiation median in CHL was 8 days later than in CHN. The hatching success of CHL was statistically less than that of CHN (41.6 vs. 69.6%). A general discriminant analysis model showed that successful CHL clutches depended on the maximum daytime wind speed (strong winds can be disastrous for breeding terns), colony identity and clutch initiation date. In the case of CHN, none of these factors had a statistically significant influence on hatching success, although the clutch initiation date was very close to being significant. These results suggest that a species which nested in the same location for a long time in relation to ambient weather conditions has higher hatching success than the one which is in the process of expanding its distribution range.
PubDate: 2016-12-30
DOI: 10.1007/s10452-016-9613-0

• Combating aggressive macrophyte encroachment on a typical Yangtze River
lake: lessons from a long-term remote sensing study of vegetation
• Authors: Qiang Jia; Lei Cao; Hervé Yésou; Claire Huber; Anthony David Fox
Abstract: Overabundant growth of emergent lacustrine plants can cause biodiversity, ecosystem service and economic loss. The two-basined Wuchang Lake is a typical small shallow lake within the Yangtze River floodplain. Expansion of the emergent macrophyte Zizania latifolia at Wuchang Lower Lake (to 49 km2 in area, c. 87.0% of Lower Lake) has increasingly denied the local community open water for fishing since the 1980s. To better understand the causes of these changes and potential remediation, we used annual Landsat imagery from 1975 to 2012 to determine the patterns of expansion between years as well as the effects of water levels in different seasons and trophic status on the annual extent of macrophytes in the Lower Lake. These analyses showed that: (1) Z. latifolia progressively covered the Lower Lake, while remaining confined to one inlet in the Upper Lake; (2) despite the generally increasing trend, there were obvious annual variations in area of Z. latifolia; (3) variation of water level in spring contributed to between-year variation in area and was significantly negatively correlated with expansion in Z. latifolia. Based on these results, to reduce the expansion in Z. latifolia, we recommend maintaining spring Lower Lake water levels above at least at 11.6 m and better at 12 m, cutting shoots in June and July, with subsequent shoot removal in autumn.
PubDate: 2016-12-19
DOI: 10.1007/s10452-016-9609-9

• Erratum to: Elevated carbon dioxide has the potential to impact alarm cue
responses in some freshwater fishes
• Authors: John A. Tix; Caleb T. Hasler; Cody Sullivan; Jennifer D. Jeffrey; Cory D. Suski
PubDate: 2016-11-30
DOI: 10.1007/s10452-016-9608-x

• Influence of the colonizing substrate on diatom assemblages and
implications for bioassessment: a mesocosm experiment
• Authors: C. L. Elias; R. J. M. Rocha; M. J. Feio; E. Figueira; S. F. P. Almeida
Abstract: Although diatoms are important bioindicators of ecological quality, their ecological traits are still not well understood. A major issue is that of substrate preferences, which may result in differences in production, and assemblage structure and composition, and which should therefore be taken into account for ecological quality assessment studies. Thus, in this work, the periphyton grown on sand and ceramic tiles in indoor controlled channels were compared to understand whether substrate differences lead to differences in: periphyton production (chlorophyll-a), chlorophyll-b and c concentrations, diatom assemblages (diversity-Shannon-Wiener, cell density, taxonomic composition, trait proportions), and ecological quality assessments (IPS-‘Indice de Polluosensibilité Spécifique’). A combined inoculum of periphyton from four Portuguese streams was introduced to the running channels (six sand and six tile) and left to colonize for 35 days. Epilithic (tiles) and epipsammic (sand) assemblages were sampled at days 14 and 35. We verified that there were no differences in chlorophyll-a concentration over time and between substrates. On both sampling occasions, the epipsammic assemblages had higher concentration of chlorophyll-c and diatom density but without significant differences over time in each substrate. The taxonomic composition was different between substrates and over time. However, these differences were not reflected in ecological quality assessment. The diversity was also similar between substrates in both sampling occasions, but it was higher at day 14. Mobile and stalked species were more abundant over the entire study and differed significantly between substrates, with the epipsammic assemblages presenting higher abundances of both traits. We concluded that the colonizing substrate influences diatom assemblages but not the ecological quality assessment.
PubDate: 2016-10-26
DOI: 10.1007/s10452-016-9605-0

• Impacts of sediment type on the performance and composition of submerged
macrophyte communities
• Authors: Lin Liu; Xiang-Qi Bu; Jun-Yan Wan; Bi-Cheng Dong; Fang-Li Luo; Hong-Li Li; Fei-Hai Yu
Abstract: To restore deteriorated lake ecosystems, it is important to identify environmental factors that influence submerged macrophyte communities. While sediment is a critical environmental factor for submerged macrophytes and many studies have examined effects of sediment type on the growth of individual submerged macrophytes, very few have tested how sediment type affects the growth and species composition of submerged macrophyte communities. We constructed submerged macrophyte communities containing four co-occurring submerged macrophytes (Hydrilla verticillata, Myriophyllum spicatum, Ceratophyllum demersum and Chara fragilis) and subjected them to three sediment treatments, i.e., clay, a mixture of clay and quartz sand at a volume ratio of 1:1 and a mixture at a volume ratio of 1:4. Compared to the clay, the 1:1 mixture treatment greatly increased overall biomass, number of shoot nodes and shoot length of the community, but decreased its diversity. This was because it substantially promoted the growth of H. verticillata within the community, making it the most abundant species in the mixture sediment, but decreased that of M. spicatum and C. demersum. The sediment type had no significant effects on the growth of C. fragilis. As a primary nutrient source for plant growth, sediment type can have differential effects on various submerged macrophyte species and 1:1 mixture treatment could enhance the performance of the communities, increasing the overall biomass, number of shoot nodes and shoot length by 39.03%, 150.13% and 9.94%, respectively, compared to the clay treatment. Thus, measures should be taken to mediate the sediment condition to restore submerged macrophyte communities with different dominant species.
PubDate: 2016-10-25
DOI: 10.1007/s10452-016-9607-y

• Effects of macrophyte-specific olfactory cues on fish preference patterns
• Authors: Charles W. Martin
Abstract: Vegetated habitats provide numerous benefits to nekton, including structural refuge from predators and food sources. However, the sensory mechanisms by which fishes locate these habitats remain unclear for many species, especially when environmental conditions (such as increased turbidity) are unfavorable for visual identification of habitats. Here, a series of laboratory experiments test whether three species of adult fish (golden topminnow Fundulus chrysotus Günther 1866, sailfin molly Poecilia latipinna Lesueur 1821, and western mosquitofish Gambusia affinis Baird and Girard 1853) use plant chemical cues to orient to one of two habitats [hydrilla Hydrilla verticillata (L.f.) Royle or water hyacinth Eichhornia crassipes (Mart.) Solms]. First, experiments in aquaria were conducted offering fish a choice of the two habitats to determine preference patterns. Next, a two-channel flume, with each side containing flow originating in one of the two habitats, was used to determine whether preferences were still exhibited when fish could only detect habitats through olfactory means. While patterns among the three fish species tested here were variable, results did indicate consistent habitat preferences despite the lack of cues other than olfactory, suggesting that these organisms are capable of discriminating habitats via chemical exudates from plants. As such, olfactory mechanisms likely provide vital information about the surrounding environment and future work should be directed at determining how anthropogenic inputs such as eutrophication and sediment runoff affect the physiology of these sensory capabilities.
PubDate: 2016-10-22
DOI: 10.1007/s10452-016-9606-z

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