Morphology-based Functional Groups Research Articles

Impacts of small dams on the phytoplankton and invertebrates in an Amazonian river

AbstractThe construction of small hydroelectric plants (SHPs) has increased greatly worldwide, and the impacts of these impoundments can cause changes in the aquatic biota. Here, we investigated the ecological attributes (abundance, richness, and species diversity) of three communities (phytoplankton, invertebrates in the water column, and benthos) and the functional groups of phytoplankton, before and after the construction of five SHPs in an Amazonian river. The communities were sampled at two sites, one upstream and another downstream of each dam or construction site, before the dam closure. The dam did not change the limnological factors, and the acid waters and low electrical conductivity, typical of “cerrado” rivers, were characteristic of both the pre‐ and post‐dam phases. For aquatic communities, the phytoplankton abundance increased and the diversity of groups decreased in the post‐dam phase. Regarding the morphology‐based functional groups (MBFG), there was an increase in groups I (small algae with a high surface/volume ratio) and V (phytoflagellates), with a reduction in groups VI (diatoms) and VII (large mucilaginous colonies) in the post‐dam phase. The relative abundance of zooplankton species increased in the post‐dam phase, and the opposite was observed for the benthic community, with reductions in abundance, richness, and group diversity in the post‐dam phase. The structure of the three communities differed between the pre‐ and post‐dam phases, but no difference in communities' similarity was observed between the upstream and downstream sites in both phases. The results show that the change in hydrodynamics, from lotic to semi‐lentic, in the reservoirs of the SHPs, was the main driving force for the alterations in the three communities. For phytoplankton, SHPs are favorable in the sense of decreasing the incidence of algal blooms, particularly of cyanobacteria.

The influence of trophic status and seasonal environmental variability on morpho-functional traits in tropical man-made shallow lakes

In the tropics, seasons are delimitated by the extent of rainfall resulting in seasonal differences in water parameters shaping phytoplankton community dynamics. Dry periods can intensify eutrophication and often result in seasonal or even perennial cyanobacterial dominance. This study was developed to evaluate phytoplankton response to trophic state and seasonal differences of environmental filters (dry and rainy periods) using the morphology-based functional groups (MBFG) approach. We also aimed at identifying environmental thresholds of each MBFG dominance in six man-made lakes located in the tropical semiarid region of Brazil. Our results showed clear MBFG association with lakes’ trophic states. The dominant groups in mesotrophic conditions were members of MBFGs V (unicellular flagellates) and VI (non-flagellated with a siliceous exoskeleton), and in meso-eutrophic MBFG IV (medium size without specialized traits) dominated. Conversely, MBFG VII (with mucilage and aerotopes) and VIII (nitrogen-fixing cyanobacteria) dominated mostly under eutrophic conditions, though linked to shallower euphotic zones. Light and phosphorous were the most important environmental thresholds associated with MBFG’s dominance. Overall, most of the lakes displayed seasonal differences in environmental filters. In contrast to what was expected, the rainy season was associated with higher nutrients, suspended solids, and reduced euphotic depth compared to the dry season. Our results, overall, show that the effects of seasonality varied across lakes and highlight eutrophication as the main environmental factor for MBFG selection suggesting reduced seasonality effects during dry years in the tropics.

Impacts of the Floc and Sink technique on the phytoplankton community: A morpho-functional approach in eutrophic reservoir water

The Floc and Sink technique promotes, through the application of coagulants and clays, the removal of phosphorus and algal biomass from the water column by flocculation and sedimentation. Although it is a promising technique for mitigating harmful cyanobacterial blooms, little is known about the impacts on other phytoplankton species as well as it is not known how species with mechanisms of resistance to sedimentation respond to the application of these products. In this study, a laboratory experiment was carried out with water from a eutrophic reservoir to assess the impact of applying aluminum-based coagulants, aluminum sulfate and polyaluminium chloride, and chitosan, alone and combined with lanthanum modified bentonite and natural bentonite on the phytoplankton community, in a functional approach based on morphology (Morphology-Based Functional Groups – MBFG, Kruk et al., 2010 and Reynolds et al., 2014), with an emphasis on the characteristics that provide resistance to sedimentation. We tested two hypotheses: phytoplankton species with adaptive mechanisms that provide buoyancy to cells are more resistant to the removal from the water column by coagulants and clays; and coagulants based on metals and modified clays are more efficient in sedimentation of microalgal cells compared to natural products, regardless of the presence of an adaptive mechanism of resistance to sedimentation. Our results showed that aluminum sulfate and polyaluminium chloride alone or combined with lanthanum modified bentonite and natural bentonite effectively sedimented the cells, regardless of the presence of buoyancy mechanisms. In contrast, the natural coagulant chitosan alone or combined with lanthanum modified bentonite and natural bentonite removed only those species that were small-celled or small colonial without specialized structures or with the presence of spines, arms and siliceous exoskeleton. In the case of species with aerotopes and flagella, the removal was not effective and still caused an increase in algal biomass due to the formation of suspended cell aggregates on the surface of the water column of the experimental units. Therefore, we concluded that the Floc and Sink technique has an impact on the phytoplankton community because it removes from the water column species that are not the target of coagulants and clays, but that are considered important sources of energy in freshwater trophic webs. This result differs according to the type of product used as well as it is related to the morphological adaptations that favor the buoyancy of cells in the water column. Species with aerotopes and flagella are more resistant to sedimentation and may make the use of products applied in the Floc and Sink technique unfeasible. Nevertheless, these results represent only an immediate effect of the technique on the phytoplankton community, thus requiring a longer time scale evaluation to determine the algae that can effectively recover water column. Therefore, we also emphasize that algae of nutritional value can recover over time and make the long-term application of the technique acceptable.

Comparison of three functional classification approaches to characterize phytoplankton response to environmental heterogeneity: a case study in NE China wetlands

Functional classification is widely recognized as an important approach for characterizing phytoplankton community response to environmental change in freshwater ecosystems. However, there are few studies of that type examining the northeast (NE) China wetlands. The study aimed to evaluate the capacities of phytoplankton functional groups (FGs), morpho-functional groups (MFGs), and morphology-based functional groups (MBFGs), to characterize phytoplankton response to environmental heterogeneity in two wetlands with different nutrient levels. Water quality variables and phytoplankton were examined in the Longfeng and Hulanhe wetlands located on the Songnen Plain, NE China, in 2013. Multivariate analyses (RDA) were performed to compare three functional classification approaches to environmental heterogeneity. Our results revealed that all three functional classification approaches (FGs, MFGs, and MBFG) could characterize the phytoplankton community response to environmental heterogeneity. MBFG had the highest cumulative percentage variance of species composition. We suggest using MBFG as a routine tool to characterize environmental heterogeneity in wetlands NE China. Furthermore, total nitrogen (TN), total phosphorus (TP), electrical conductivity (EC), and pH were key predictors for regulating the ecological distribution of the phytoplankton community pattern in the study area. This study further highlights that MBFG is a relevant tool in assessing ecological health in wetland ecosystems.

Clumpy coexistence in phytoplankton: the role of functional similarity in community assembly

Emergent neutrality (EN) suggests that species must be sufficiently similar or sufficiently different in their niches to avoid interspecific competition. Such a scenario results in a transient pattern with clumps and gaps of species abundance along the niche axis (e.g. represented by body size). From this perspective, clumps are groups of coexisting species with negligible fitness differences and stochastic abundance fluctuations. Plankton is an excellent model system for developing and testing ecological theories, especially those related to size structure and species coexistence. We tested EN predictions using the phytoplankton community along the course of a tropical river considering 1) body size structure, 2) functional clustering of species in terms of morphology‐based functional groups (MBFG) and 3) the functional similarity among species concerning their functional traits. Two main clumps in the body size axis (clump I and II) were conspicuous through time and were detected in different stretches of the river. Clump I comprised medium‐sized species from the MBFGs IV, V and VI while clump II included large‐bodied species from the MBFGs V and VI. Pairwise differences in species biovolume correlated with species functional similarity when the whole species pool was considered, but not among species within the same clump. Although clumps comprised multiple MBFGs, the dominant species within the clump belonged always to the same MBFG. Also, within‐clump species biovolume increased with functional distinctiveness considering both seasons and stretches, except the lower course. These results suggest that species within clumps behave in a quasi‐neutral state, but even minor shifts in trait composition may affect species biovolume. Our findings point that EN belongs to the plausible mechanisms explaining community assembly in river ecosystems.

Species composition and diversity of epiphytic microalgae on Myriophyllum spicatum in the El-Ibrahimia Canal, Egypt

The El-Ibrahimia Canal is one of the main irrigation sources in Egypt, that it supplies perennial irrigation to approximately 600 000 ha (one-fourth of the Egyptian cultivated land). An annual study on species composition of microalgae attached to the submerged hydrophyte Myriophyllum spicatum L. was carried out from midautumn 2016 to midsummer 2017. Epiphytic microalgae were represented by 109 species related to 66 genera. Diatoms were the most abundant group (66–95%) followed by green algae (3.3–25%). Aulacoseira granulata, Cyclotella ocellata, Cymbella affinis, Gomphonema parvulum, Navicula cuspidata, Navicula muralis, Nitzschia dissipata, Nitzschia hungerica, Staurosirella leptostauron, and Ulnaria ulna were the most dominant species. Regarding morphology-based functional groups (MBFGs) taxonomic approach, the epiphytic microalgae species were represented by six MBFGs (I, III, IV, V, VI and VII). The MBFG VI (mainly diatoms) was the leading group with a minimum average percentage of 59.9% during the summer season and a maximum of 95.06% during the winter season. The mean annual values of cell density fluctuated greatly between 8.6 × 106 (during the spring season) and 4.7 × 107 cells g−1 plant wet weight (during winter season). The changes in microalgae biovolumes have the same trend as cell density, with mean seasonal values of 3.89 × 109, 2.56 × 1010, 1.16 × 109, and 3.21 × 109 µm3 g−1 plant wet weight during autumn, winter, spring and summer seasons, respectively. Diversity index values ranged between 2.0 and 3.0, revealing a light pollution status of the canal. In general, the species composition and diversity of epiphytic algae along the El-Ibrahimia Canal are highly dependent on site and the physico-chemical properties of canal water affected by agricultural practice around it.

A trait‐based approach predicting community assembly and dominance of microbial invasive species

Understanding the mechanisms underlying community assembly helps to define success and susceptibility to biological invasions. Here, we explored phytoplankton community assembly following niche and neutral paradigms and using a trait‐based approach. Under the hypothesis that the morphology‐based functional groups (MBFG) clusters species with similar niche, we analysed how trait‐related differences in fitness influence dominance of an invasive species. This was based on literature review, field data and model simulations. We predict that invading species can be dominant if: 1) do not belong to the local MBFG but use unexploited areas of the niche, or 2) belong to the resident MBFG but exhibit a higher fitness due to a particular combination of traits. The invasive dinoflagellate Ceratium furcoides was used as the model species to evaluate these hypotheses, its morphological (e.g. volume) and physiological (e.g. growth rates) traits were compared with species from the same (V: photosynthetic flagellates) and different (VII: colonial cyanobacteria) MBFG. Fitness was estimated using models parametrized with MBFG rates (R*, ability to draw down phosphate) under different environmental conditions (i.e. flushing). Results contributed to support both hypotheses. First, the alternation of C. furcoides and cyanobacteria dominance was explained by the use of different niches. Secondly, species from MBFG V were dominant under similar environments. Within this group V C. furcoides showed higher fitness under low flushing and high predation, advantage provided by a distinctive combination of traits. The application of trait‐based approaches to represent the niche and estimate fitness along environmental gradients was useful to evaluate community assembly and can be used to predict the dominance of microbial species invasions.

基于功能类群分析呼兰河口湿地浮游植物群落结构特征

PDF HTML阅读 XML下载 导出引用 引用提醒 基于功能类群分析呼兰河口湿地浮游植物群落结构特征 DOI: 10.5846/stxb201911152444 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目（31870187）；哈尔滨师范大学科研启动金项目（XKB201912）；哈尔滨师范大学高等教育教学改革研究项目，哈尔滨师范大学研究生教育教学改革项目 Analysis of phytoplankton structure based on different functional groups in Hulanhe Wetland Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:浮游植物对水环境条件变化敏感，其群落演替特征被广泛应用于指示水环境变化。基于3种浮游植物功能类群方法，对呼兰河口湿地浮游植物群落结构进行研究。于2018年春季（4、5月）、夏季（6、7、8月）和秋季（9、10月）三季，在呼兰河口湿地共设置11个采样点，通过ASNOSIM和SIMPER分析探索FG、MFG和MBFG功能类群的演替特征，基于RDA分析阐述功能类群对环境因子的响应模式。研究期间共鉴定浮游植物243个分类单位，隶属于7门9纲18目32科75属；其种类组成主要以绿藻门（46.09%）、裸藻门（19.34%）和硅藻门（18.52%）为主。共划分FG功能类群25个，MFG功能类群20个，MBFG功能类群6个；ANOSIM分析表明不同季节之间FG和MFG功能类群结构差异显著；SIMPER分析表明S1/Lo/W1/P/J/Y、9b/5a/11b/6a/2c/2d/1c和Ⅲ/Ⅰ类群是影响不同季节之间功能类群变化的主要类群；RDA分析表明，FG、MFG和MBFG功能类群的演替受多种环境因素共同影响，其中pH、BOD5、Tur.和CODMn与功能类群演替关系密切。相较于MBFG功能类群，FG和MFG功能类群能更好的响应呼兰河口湿地水环境的空间异质性。 Abstract:The Hulanhe Wetland is located in northeastern of China, and plays an important role in maintaining the biodiversity and regulating the microclimate in Harbin city. Although phytoplankton functional group studies on wetlands in northern China have increased recently, studies of the phytoplankton functional group in the Hulanhe Wetland are limited. To better understand processes of phytoplankton community succession in relation to environmental parameters, the functional mechanisms of biological communities may be better understood if species are pooled into groups with similar characteristics. Therefore, a detailed survey of three phytoplankton functional groups in spring, summer, and autumn are necessary. In this study, three different phytoplankton functional group methods were used to study phytoplankton community structure. Phytoplankton was qualitatively and quantitatively collected from 11 sampling sites in four typical habitats. The samples were collected in spring (April, May), summer (June, July, August), and autumn (September, October). A total of eleven sample sites were selected. We explored the succession characteristics of FG (Functional Group), MFG (Morpho-Functional Group) and MBFG (Morphology-Based Functional Group) functional groups by applying ASNOSIM and SIMPER analysis. A total of 243 phytoplankton species were identified, belonging to 7 phyla, 9 classes, 18 orders, 32 families and 75 genera. The phytoplankton species composition was dominated by and Chlorophyta (46.09%), followed by Euglenophyta (19.34%), Bacillariophyta (18.52%) and Cyanophyta (11.11%). During the study, the results showed that the average abundance of phytoplankton in the Hulanhe Wetland was significantly different (P<0.05). According to the abundance of phytoplankton, B (Cyclotella Kützing), J (Scenedesmus Meyen, Tetrastrum Chodat), D (Nitzschia Hassall), S1 (Pseudanabaena limnetica (Lemmermann) Komárek), Y (Cryptomonas erosa Hering, Cryptomonas ovata Hering) and W1 (Euglena Ehrenberg, Phacus Dujardin) were dominant in the functional groups. 25 functional groups, 20 Morpho-Functional Groups and 6 Morphology-based Functional Groups were identified during the study. The ANOSIM analysis showed significant differences in FG and MFG functional group structures between seasons. The SIMPER analysis indicated that the primary contributing phytoplankton functional groups were S1/Lo (Merismopedia Meyen)/W1/P (Melosira granulata (Ehrenberg) Ralfs)/J/Y, 9b (small unicells-Chlorococcales)/5a (thin fifilaments Oscillatoriales)/11b (Chlorococcales-Gelatinous colonies)/6a (large Centrics)/2c (small Euglenophytes)/2d (Cryptophytes)/1c (large Euglenophytes) and Ⅲ (large fifilaments)/Ⅰ (small organisms with high S/V). Redundancy Analysis (RDA) based on FG, MFG and MBFG and eleven environmental variables revealed that CODMn was the key factor driving the phytoplankton functional group succession, and Turbidity (Tur.), BOD5 and pH were closely related to phytoplankton functional group patterns. We found that MBFG approach was not as sensitive as FG and MFG approach in describing the variability of phytoplankton groups in the environment. We suggested that MBFG approach was not suitable for indicating the temperate wetland water environment condition. 参考文献 相似文献 引证文献

Effects of Phytoplankton Classifications on the Relationship Between Phytoplankton Community and Environment in Summer Subtropical Reservoirs, Southern China

Phytoplankton communities are sensitive to environmental changes and are used to assess water quality and ecosystem states. However, their responses to environment are affected by the classifications. To understand the impact of different classifications, the response relationship between phytoplankton communities and environment were compared with five phytoplankton classifications (species, genus, phyla, morphology-based functional groups, and functional groups) by investigating eight reservoirs in summer in the southern subtropical region. The eight reservoirs were mesotrophic and their environment was characterized by a high temperature (32.6±1.1)℃ and low light bioavailability (Zeu/Zm was 0.48±0.28). The variance of dissolved nutrients contributed to the main environmental differences between the eight reservoirs. The environmental gradient, in terms of dissolved nutrients concentration, was significantly higher than in terms of total nutritional status, temperature, and light bioavailability (P<0.05). The number of species and genus was higher but their biomass was lower than those of other classifications. This contributed to the higher Bray-Curtis distance and lower species gradient (SCBD) and location gradient (LCBD) of phytoplankton communities with species and genus classifications than other classifications. A statistical analysis showed that only the phytoplankton community gradient with MBFG and phylum classifications was significantly correlated with environmental gradient, in particular the gradient of pH value and PO43--P concentration. A significant regress was detected between the TSI gradient and the phytoplankton community gradient with MBFG and phylum classifications. In conclusion, as the variance of environment stemmed from the supply of nutrients, the response of the phytoplankton community classified with MBFG and phylum was more sensitive than other classifications.

Chrysophyte stomatocysts and their associations with environmental variables in three peatlands in the subtropical monsoon climate zone of China

Peatlands are critical ecosystems in regulating global carbon cycle and hosting distinctive biodiversity. Chrysophyte stomatocysts, siliceous resting stages of golden-brown algae, are widely distributed in acidic and oligotrophic environments of peatlands. Presently, little knowledge is available on the composition and distribution of stomatocysts in subtropical peatlands. This study investigated the communities of moss-inhabiting stomatocysts in three Sphagnum-dominated peatlands in central China, and their association with environmental variables. Fifty-nine stomatocyst morphotypes with two additional formae were identified according to the International Statospore Working Group guidelines, and stomatocyst assemblages were significantly different among the three peatlands. In addition, these stomatocyst morphotypes were classified into eight morphology-based functional groups according to morphological traits, such as types of collar and ornamentation. Redundancy analyses revealed that stomatocyst assemblages at both morphotype- and functional group-level were significantly correlated with depth to water table, oxidation reduction potential, and morphotype-level composition was further related to electronic conductivity and potassium. Generally, cysts with a complex collar preferred dry hummocks, while large cysts with long spines mainly occurred in wet hollows. This study highlights the usage of chrysophyte stomatocysts as potential bioindicators for environmental changes in these subtropical peatlands, as well as similar peaty environments.

Responses of morphology-based phytoplankton functional groups to spatial variation in two tropical reservoirs with long water-residence time

ABSTRACT The responses of phytoplankton to the spatial variation of 2 tropical reservoirs with long water-residence times was studied by means of morphology-based functional groups (MBFGs). The groups were compared among the pelagic, tributary, and downstream zones to determine the spatial distribution and its main drivers. Based on the zonation concept, we hypothesized that phytoplankton tolerant to nutrient depletion would be more important in the pelagic zones, and phytoplankton resistant to light limitation and turbulence would be more important in the lotic zones. We also expected nutrients and/or light availability (bottom-up control) to be the main drivers of MBFGs spatiality in tropical systems. Our results indicated the importance of this control for phytoplankton spatial distribution. The phytoplankton biovolume was more homogeneous in Serra da Mesa Reservoir (SER), while in Três Marias Reservoir (TRM) biovolume was higher in the pelagic zone. MBFG III dominated in the pelagic zone of TRM while MBFG V dominated in its tributary. The higher biovolume of MBFG III was associated with low dissolved phosphate and high water temperature and pH in SER, and lower dissolved inorganic nitrogen and high pH in the pelagic zone of TRM, as shown by RDA analyses. The dominance of MBFG V in the tributary is probably a response to higher turbidity and dissolved organic carbon availability. We conclude that within zones, resources (nutrients and light availability), temperature, and pH were the main drivers of the phytoplankton in these reservoirs. Furthermore, the MBFG scheme can be used to monitor phytoplankton spatial distribution.

Light, but Not Nutrients, Drives Seasonal Congruence of Taxonomic and Functional Diversity of Phytoplankton in a Eutrophic Highland Lake in China.

Information on temporal dynamics of phytoplankton communities and their responses to environmental factors can provide insights into mechanisms driving succession of phytoplankton communities that is useful in programs to manage and or remediate undesirable assemblages. Populations of phytoplankton can be controlled by bottom-up factors such as nutrients and temperature or top-down such as predation by zooplankton. Traditionally, taxonomic diversity based on morphologies has been the measure used for analysis of responses to environmental factors. Recently, according to functional groupings, including functional groups (FG), morpho-FG (MFG), and morphology-based FG (MBFG), functional diversity has been used to represent functional aspects of phytoplankton communities. However, to what extent these taxonomic and functional groupings are congruent at seasonal time-scales and the main environmental factors, which drive succession, have remained less studied. Here, we analyzed absolute and relative proportions of a phytoplankton community during a 3-year period in Lake Erhai, a eutrophic highland lake in China. Alpha diversity and beta diversity, as measured by Shannon-Wiener and Bray-Curtis indices of taxonomic grouping and three functional groupings (FG, MFG, and MBFG) were applied to investigate environmental factors determining diversity. Significant, positive relationships were observed between taxonomic diversity and functional diversity that were strongly linked through seasons. In order to exclude the influence of dominant species' tolerance to extreme environments, the dominant species were excluded one by one, and the results showed that residual communities still exhibited similar patterns of succession. This synchronous temporal pattern was not principally driven by the dominant genera (Microcystis, Psephonema, and Mougeotia). Instead, the entire phytoplankton community assemblages were important in the pattern. Most diversity indices of taxonomic and functional groupings were significantly correlated with solar irradiance, but not nutrient concentrations. Because the lake is eutrophic and there were already sufficient nutrients available, additional nutrients had little effect on seasonal taxonomic and functional diversity of phytoplankton in Lake Erhai.

Alternatives for the biomonitoring of fish and phytoplankton in tropical streams

Biomonitoring programs need to balance accurate responses in assessments of changes in biological communities with sampling that is fast and low cost. In this study, we evaluated the concordance among fish and phytoplankton communities of streams. We tested the cross-taxa surrogacy, taxonomic, numerical resolution and ecological substitute group (habitat use and trophic guilds) resolution with Procrustes analyses aim of simplifying the biomonitoring process. We collect a total fish abundance of 8,461 individuals, represented by the ecological classes of habitat, including benthic, nektonic, nektobenthic, marginal and trophic guilds by detritivore, terrestrial invertivore, aquatic invertivore, piscivore, algivore and herbivore. We sampled a phytoplankton total density of 1,466.68 individuals/ml, represented by four Morphology-Based Functional Groups and nine Reynolds Functional Groups. Our results don’t support the use of substitute groups among fish and phytoplankton. For fish, habitat use and trophic guild are good surrogates for species-level data. Additionally, our results don’t support the use of functional groups as surrogates for phytoplankton. We suggest the use of higher taxonomic levels (genus and family) and record only the occurrence of species and/or genus for fish and phytoplankton. Our findings contribute to decreasing the costs and time of biomonitoring programs assessments and/or conservation plans on fish and phytoplankton communities of headwater streams.

Variación temporal de la morfología funcional del fitoplancton en una planicie inundable del Caribe Colombiano

Analizamos la variación temporal de los grupos funcionales basados en la morfología del fitoplancton (GFBM) en el sistema inundable de Ayapel a través de la comparación de dos muestreos previos realizados entre los 2005 y 2007 y uno nuevo hecho en el 2015. Se estimó el biovolumen (mm3.l-1) y los rasgos morfológicos como volumen, relación superficie/volumen (S/V) y dimensión linear máxima (DLM). El análisis temporal fue realizado acorde con los niveles de precipitación pluvial, y mediante un análisis de agrupamiento se definieron dos períodos previos (época seca y época de transición) y uno nuevo correspondiente al año 2015 (msENSO: época seca con influencia ENSO). En las épocas seca y de transición, el grupo predominante fue el GFBM III con altas DLM (108.77 µm) y relaciones S/V (1.44 µm), mientras que en el msENSO se observaron bajos biovolumenes (0.016 mm3.l-1) y la predominancia del GFBM V. La comparación de la morfología funcional entre los años evidenció la transición de formas filamentosas a formas flageladas del fitoplancton, permitiéndole un mejor ajuste ante las presiones ambientales del área de estudio.

Seasonal variation of phytoplankton community and its relationship with environment in subtropical reservoirs: A comparison between two methods of functional groups classification

Phytoplankton is the most important biological component in the reservoir ecosystem, which could indicate the status of aquatic ecosystem due to its sensitive to environmental variation. To understand the application and difference between two methods of phytoplankton functional group classification, functional groups (FG) and morphology-based functional groups (MBFG), in indicating the changes of reservoir environment, we investigated water quality and phytoplankton in Qingshitan Reservoir monthly from March 2016 to February 2017. Two phytoplankton functional groups classifications (FG and MBFG) were used to analyze phytoplankton community composition, seasonal succession, and its driving factors. We compared the application and differences of two methods of functional group classifications in indicating environmental changes. The results showed that there were 109 species belonged to seven phylum, which could be classified into 17 FG or 5 MBFG functional groups. Results from both methods indicated that the reservoir was meso-eutrophic. The phytoplankton seasonal succession under 8 or 9 steps with FG or 8 steps with MBFG. Results from the redundancy analysis showed that the response of phytoplankton community reflected with FG to environmental variation was more sensitive than that with MBFG, especially in the response to the changes of pH and nitrate concentration. In conclusion, FG was more appropriate in describing community succession and exploring the relationship between phytoplankton and environment.

Phytoplankton–zooplankton relationships based on phytoplankton functional groups in two tropical reservoirs

The aim of this study was to evaluate the phytoplankton–zooplankton interaction, using phytoplankton morphology-based functional groups, in two reservoirs that have different trophic state indices (TSIs). We hypothesised that the herbivorous relationships of zooplankton with the phytoplankton community would differ between reservoirs with different TSIs. In order to test this hypothesis, field collections to study the phytoplankton, zooplankton and abiotic variables were undertaken between July 2016 and April 2017 from the subsurface layer and in situ experiments were conducted using biomanipulation of the micro- and mesozooplankton. In situ experiments consisted of 18 microcosms in 5-L transparent plastic bottles (in triplicate). The mesotrophic reservoir showed predominance of chlorophytes (Group IV) and mesozooplankton during the study period. In the presence of zooplankton, all phytoplankton groups showed negative growth rates and higher ingestion values, mainly Group IV. In the supereutrophic reservoir, ingestion rates showed that micro- and mesozooplankton reduced the biomass of colonial (Group VII) and filamentous (Group III) cyanobacteria respectively. The findings of the present study reveal that Copepoda Calanoida, as well as small cladocerans, may be the most suitable zooplankton groups for biomass biomanipulation of different morphofunctional phytoplankton groups in mesotrophic reservoirs, and for the control of cyanobacteria in supereutrophic reservoirs.

Grupos funcionales fitoplanctónicos en una laguna algal de alta tasa usada para la biorremediación de lixiviados de rellenos sanitarios

The functional group (FG) approach is used to predict the response of the composition of phytoplankton species to changes in the environmental conditions. We assessed for the first time the dynamics of phytoplankton communities in a High-Rate Algal Pond (HRAP), implemented for the bioremediation of landfill leachate, and using morphology-based functional groups (MBFG), under the American tropics conditions. These groups were later correlated with the physical and chemical variables of the system. Water samples were taken for biological, physical and chemical analysis for seven months. In addition, phytoplankton biovolumes were estimated and a canonical correlation analysis was performed to explain the relation between physical and chemical variables and FGs. Subsequently, the HRAP treated a medium-age leachate characterized by high concentrations of nutrients. Four MBFGs were identified (IV, V, VI and VII). Group V, conformed by phytoflagellates, was found to be dominant during the entire study period. This group proliferate in environments with high concentrations of organic matter, while contributing to the transformation of the contaminants present in the leachate. The largest biovolumes of Groups V and VII occurred during periods of low water levels and dissolved organic carbon. Finally, we show that the MBFG technique may be useful in understanding the dynamics of the phytoplankton community in the HRAP used for the treatment of landfill leachate.

Morphology-based functional groups as the best tool to characterize shallow lake-dwelling phytoplankton on an Amazonian floodplain

River floodplains are subject to different inundation scenarios, mainly related to the flood pulse. Moreover, the ecology of floodplain lakes is modulated by exchanges of water with the main stream. On Amazonian floodplains, the water level fluctuates seasonally, with four distinct stages during the year: rising, high, falling, and low water. This study evaluated how/which three functional approaches to phytoplankton (FG, functional groups; MFG, morphofunctional groups; and MBFG, morphology-based functional groups) showed the largest relation to the environmental variations in response to rising and falling water periods, using data of the seven lakes sampled during rising and falling water periods, on the Curuaí Floodplain system, Pará state, Brazil. We used a Principal Coordinates Analysis to check for differences in phytoplankton species composition between the rising and falling water periods and a Redundancy Analysis to evaluate the relationship between functional approaches and environmental. Electrical conductivity, silica, and pH were the most important environmental variables to structuring the phytoplankton. The biological dissimilarity was computed using Bray-Curtis index for species biovolume and indicated greater similarity among the species compositions in the lakes during the falling water period. During rising water species is adapted in almost all lentic ecosystems (FG Y) and autotrophic organisms typical from the meroplanktonic that can be found in phytoplankton samples of the shallow lakes (FG MP); cryptomonads (MFG 2d), large centrics (MFG 6a), and large pennates (MFG 6b); and non-flagellated organisms with siliceous exoskeletons (MBFG VI) and unicellular flagellates of medium to large size (MBFG V) were predominant. During falling water, species that tolerate eutrophic to hypertrophic environments with low nitrogen content predominated all shallow lakes (FGs H1 and M; MFGs 5e and 5b; and MBFGs III and VII) and Dolichospermum spp. formed blooms. Morphology-based functional groups were the larger relation with the environmental variations than did functional groups and morphofunctional groups. MBFGs provides a relatively simple and objective classification and were the best in characterizing phytoplankton dynamics on the Curuaí floodplain. Therefore, we recommend using these groups to study phytoplankton ecology in shallow floodplain lakes.

Variability in mean size of phytoplankton in two floodplain lakes of different climatic regions

Phytoplankton size has an important functional role in ecosystem processes, such as nutrient production and cycling. It has been suggested that warmer temperatures may favor the smaller organisms in biological communities. We evaluate the mean size of the phytoplankton organisms and apply a morphology-based functional groups (MBFG) approach. We use time series of two floodplain lakes that present mean annual temperature difference of 10°C and similar hydrodynamic, area, and mean depth. We expected that a smaller mean size of MBFGs would be associated with higher temperatures. The Akaike Information Criterion was used to investigate environmental factors predicting the mean size of MBFGs within each lake. The mean size was most associated to nutrients and dissolved oxygen in the subtropical lake, and to temperature in the temperate lake. Large filaments with aerotopes and the small flagellated with siliceous exoskeletal structures showed high mean size at higher temperatures, thus contradicting temperature–size rules. Probably the high variability of mean size was provided by the high variability observed around environmental factors. Our findings reveal that other functional traits may be associated with the phytoplankters mean size, which result in adaptation to high variability of various environmental factors.

Morphology-based differences in the thermal response of freshwater phytoplankton.

The thermal response of maximum growth rate in morphology-based functional groups (MBFG) of freshwater phytoplankton is analysed. Contrasting an exponential Boltzmann-Arrhenius with a unimodal model, three main features were evaluated: (i) the activation energy of the rise (Er), (ii) the presence of a break in the thermal response and (iii) the activation energy of the fall (Ef). The whole dataset (N = 563) showed an exponential increase (Er ∼ 0.5), a break around 24°C and no temperature dependence after the breakpoint (Ef = 0). Contrasting thermal responses among MBFG were found. All groups showed positive activation energy (Er > 0), four showed no evidence of decline in growth rate (temperature range = 0-35°C) and two presented a breakpoint followed by a sharp decrease in growth rate. Our results evidenced systematic differences between MBFG in the thermal response and a coherent response significantly related to morphological traits other than size (i.e. within MBFG). These results provide relevant information for water quality modelling and climate change predictions.