PHYTOPLANKTON BIOMASS INCREASES IN A SILT-IMPACTED AREA IN AN AMAZONIAN FLOOD-PLAIN LAKE OVER 15 YEARS

Funding Information: We thank Mineração Rio do Norte S.A. and Limnologia/UFRJ for fieldwork support, Dr. Janet W. Reid (JWR Associates) for language revision, and Leonardo Preza Rodrigues for map charting. VLMH, JCN, FAE, RLB, and FR are partially supported by the National Council for Scientific and Technological Development (CNPq), Brazil, RLB, and FAE by FAPERJ, Brazil, and CGR financially supported by Sakari Alhopuro Foundation, Finland. Publisher Copyright: © 2022, Universidade Federal do Rio de Janeiro. All rights reserved.Tailings from bauxite mining in Porto Trombetas (Pará state, Central Amazonia, Brazil) was discharged (1979–1989) into Batata Lake affecting about 30% of its area. The lake belongs to a clear-water flood-plain system along the Trombetas River, a tributary of the Amazon River. Siltation is the main perceived factor impacting aquatic and flooded communities. Besides natural regeneration, a program to restore a section of igapó forest in the impacted area (IA) has been conducted since 1991. Decreased light is the main factor reducing total phytoplankton biomass (PhyBM) in IA. We hypothesized that PhyBM in IA increases over time because of the improvement of the underwater light conditions due to the natural regeneration and restoration. We sampled quarterly PhyBM and limnological variables (depth, transparency, temperature, pH, conductivity, dissolved oxygen, turbidity, suspended solids, total Kjeldahl nitrogen, and total phosphorus), over 15 years (2005–2019) at eight sampling sites in the two areas (N = 349). We also obtained daily climatic and hydrologic data. PhyBM was higher in NIA than in IA. The temporal trend in the annual mean of PhyBM increased significantly over time only in the IA, approximating the NIA values, confirming our general hypothesis. The increase of PhyBM in the IA was negatively related to the residual light attenuation caused by non-phytoplankton turbidity and to total phosphorus, and positively to air temperature and site depth (p < 0.05; Marginal r2 = 0.18; Conditional r2 = 0.29). Instead, in NIA, PhyBM was explained only by the increase in air temperature (p < 0.05; Marginal r2 = 0.15; Conditional r2 = 0.34). We concluded that the PhyBM in the IA positively responds to the synergy between increasing light availability, air temperature, and site depth, and decreasing total phosphorus concentrations, regardless of hydrologic phase.Peer reviewe

Microalgae community of the Huaytire wetland, an Andean high-altitude wetland in Peru

AIM: The diversity and distribution of microalgae communities in a high-altitude (3,000 to 4,500 m a.s.l) Andean wetland, regionally known as bofedal, were examined to assess seasonal and spatial patterns. METHODS: Samples were taken monthly from June to December, 2008 at 13 stations in the Huaytire wetland (16° 54’ S and 70° 20’ W), covering three areas (impacted by urban land use, impacted by camelid pasture, and non-impacted) and three climatologically induced periods (ice-covered, ice-melt and ice-free). RESULTS: A total of 52 genera of algae were recorded. Diatoms were the predominant group in abundance and richness. We found a significantly higher abundance during the ice-melting period, when light exposure and runoff were intermediate, in comparison to the ice-covered (low light and flushing) and ice-free (high light and low runoff) periods. Microalgae abundance was significantly lower in the non-impacted area compared to the sites close to the urban area and to the camelid pastures. Alpha diversity ranged from 8 to 29 genera per sample. High genera exchange was observed throughout the wetland, showing a similar floristic composition (beta diversity = 4%). CONCLUSIONS: We found that diatoms were dominant and adapted to the extreme conditions of the Andean wetland, showing higher abundance during the ice-melt period and in the livestock area. Also, taxa richness was higher in the ice-melt period and in the most-impacted areas

Fitoplâncton de rede da Lagoa do Campelo, Campos, Rio de Janeiro, Brasil: uma contribuição a seu conhecimento

Este estudo visa contribuir ao conhecimento taxonômico do fitoplâncton de rede da Lagoa do Campelo, Município de Campos, Rio de Janeiro. Analisaram-se amostras referentes aos períodos de chuva e estiagem, tendo sido identificados 42 táxons a níveis específicos e infra-específicos, destes, 8 constituem primeira ocorrência para o Estado. O período de chuvas é caracterizado por maior riqueza de espécies

Fitoplâncton de rede da Lagoa de Cima, Campos (Rio de Janeiro, Brasil): uma contribuição a seu conhecimento

The paper aims at the taxonomic survey of the net plankton algae of "Lagoa de Cima", located in the Municipality of Campos (21°46'28"S, 41°31'15"W), and which contributes economically to the region besides being an important leisure site. Based on samples collected in periods both of rain and draught, 64 taxa were identified to specific and infraspecific levels and presently described in details. Out of these, 7 are member of the Cyanophyceae, 18 of Chlorophyceae, 20 of Zygnemaphyceae, 10 of Euglenophyceae, 3 of Bacillariophyceae, 2 of Chrysophyceae, 3 of Xanthophyceae, and 1 of Dinophyceae.Este trabalho contribui ao levantamento taxonômico das algas planctônicas de rede da Lagoa de Cima, Município de Campos (21°46'28"S, 41°31'15"W) a qual contribui economicamente para a região além de ser importante área de lazer para a comunidade. Com base na análise de amostras coletadas em períodos de chuva e de estiagem identificaram-se 64 táxons a níveis específico e infra-específico, os quais estão descritos e ilustrados neste trabalho. Destes, 7 são representantes de Cyanophyceae, 18deChlorophyceae, 20 de Zygnemaphyceae, 10 de Euglenophyceae, 3 de Bacillariophyceae, 2 de Chrysophyceae, 3 de Xanthophyceae e 1 de Dinophyceae

Tilapia rendalli increases phytoplankton biomass of a shallow tropical lake

AIM: This study aimed to experimentally test the influence of a planktivorous filter-feeding fish (Tilapia rendalli) on the phytoplankton dynamics of a small and shallow tropical reservoir (Lake Monte Alegre, Brazil). Adults of T. rendalli of this lake feed preferentially on phytoplankton, and we hypothesize that: I) adults of T. rendalli will decrease the phytoplankton biomass and composition through direct herbivory, and II) as it is a eutrophic system, fish would not have strong influence on phytoplankton through nutrient cycling. METHODS: To evaluate these different effects on algae, a field experiment was performed in the summer period for 15 days, in mesocosms isolated from the sediment, using a control group (no fish) and a treatment group (with one fish in each mesocosm). Physical and chemical variables and phyto- and zooplankton were evaluated at the start, middle, and end of the experiment. RESULTS: At the end of the experiment, it was observed a significant increase in ammonium concentrations and total phytoplankton biomass, Cyanobacteria and Zygnemaphyceae and all size classes except class II (20-30 µm) in the treatment group (with fish). The biomass increase of the potentially toxic cyanobacterium Cylindrospermospsis raciborskii was also observed in the fish treatment at the end of the experimental period. CONCLUSION: This study did not support both initial hypotheses. It supports the assertion that in tropical water bodies, with similar characteristics to the environment studied, planktivorous filter-feeding fish, such as T. rendalli, are not effective in reducing phytoplankton biomass through direct grazing, even when phytoplankton is one of their main food items. T. rendalli can contribute to the increase of phytoplankton biomass and can promote or increase the eutrophication of aquatic systems

Phytoplankton diel variation and vertical distribution in two Amazonian floodplain lakes (Batata Lake and Mussurá Lake, Pará-Brasil) with different mixing regimes

Both phytoplankton diel variation and vertical distribution were studied in two clear water Amazonian floodplain lakes (Batata and Mussurá) during the high water hydrological period. Small chlorococales, especially Chlorella homosphaera SKUJA in both Batata and Mussurá lakes, Cryptomonas marsonii SKUJA, Cryptomonas pyrenoidifera GEITLER and Mougeotia delicata BECK, in Batata Lake, and C. marsonii, Cryptomonas curvata EHRENBERG and Chromulina gyrans STEIN in Mussurá Lake were the most representative algal populations. Reduced phytoplankton densities were found in Batata Lake, with a stratified vertical distribution during the day and tendency to a more even distribution from the end of night time to sunrise. On the other hand, the highest phytoplankton densities were observed in Mussurá Lake, being concentrated mainly in superficial layers (0-3 meters) during a 24-hour cycle. In both lakes, higher concentrations were found during the middle of the day. Hydrological and hydrographical conditions may be the reason for such different behaviour between Batata Lake and Mussurá Lake. © MPI für Limnologie, AG Tropenökologie, Plön; INPA, Manaus

Taxonomy and ecology of Synedropsis roundii sp. nov. (Bacillariophyta) from a tropical brackish coastal lagoon, south-eastern Brazil

A new Synedropsis species is described from a coastal tropical lagoon in south-eastern Brazil. This species has a single chloroplast in both views of the valve, apical pore fields composed of three slits, and uniseriate striae. It is planktonic and was found in brackish water. Synedropsis roundii is the eighth Synedropsis species to be described and the first to be found in a tropical region. We studied the seasonal dynamics of S. roundii, which can form blooms in the coastal Imboassica Lagoon, Rio de Janeiro state, Brazil. Continuous mixing of this shallow environment is suggested to be an important physical factor determining the success of the species. Availability of soluble reactive silicon is thought to be the main factor regulating the large biomass fluctuations. In the classification of Reynolds in 1997 (Vegetation processes in the pelagic: a model for ecosystem theory. Ecology Institute, Oldendorf, Germany, 371 pp.), S. roundii appears to belong to D-assemblage, a set of small and fast-growing diatoms, well represented in small, shallow and enriched waters. We also offer a tentative habitat template for S. roundii

Mitigation measures for controlling and managing cyanobacterial blooms in a tropical shallow urban pond in Southeast Brazil

Miranda M, Pacheco FS, Noyma N, Huszar VLM, Mucci M, Lürling M, Ometto JP, Marinho MM. 2023. Mitigation measures for controlling and managing cyanobacterial blooms in a tropical shallow urban pond in Southeast Brazil. SILnews 81

Managing Eutrophication in a Tropical Brackish Water Lagoon : Testing Lanthanum-Modified Clay and Coagulant for Internal Load Reduction and Cyanobacteria Bloom Removal

The release of phosphorus (P) stored in the sediment may cause long-term delay in the recovery of lakes, ponds, and lagoons from eutrophication. In this paper, we tested on a laboratory scale the efficacy of the flocculant polyaluminium chloride (PAC) and a strong P-binding agent (lanthanum-modified bentonite, LMB) on their ability to flocculate a cyanobacterial bloom and hamper P release from a hypertrophic, brackish lagoon sediment. In addition, critical P loading was estimated through PCLake. We showed that cyanobacteria could be effectively settled using a PAC dose of 2 mg Al L−1 combined with 400-mg L−1 LMB; PAC 8 mg Al L−1 alone could also remove cyanobacteria, although its performance was improved adding low concentrations of LMB. The efficacy of LMB to bind P released from the sediment was tested based on potentially available sediment P. A dose of 400 g LMB m−2 significantly reduced the P release from sediment to over-standing water (either deionized water or water from the lagoon with and without cyanobacteria). In sediment cores, LMB + PAC reduced sediment P flux from 9.9 (± 3.3) to − 4.6 (± 0.3) mg P m−2 day−1 for the experimental period of 3 months. The internal P load was 14 times higher than the estimated P critical load (0.7 mg P m−2 day−1), thus even if all the external P sources would be ceased, the water quality will not improve promptly. Hence, the combined LMB + PAC treatment seems a promising in-lake intervention to diminish internal P load bellow the critical load. Such intervention is able to speed up recovery in the brackish lagoon once external loading has been tackled and at a cost of less than 5% of the estimated dredging costs.</p

Coagulant plus ballast technique provides a rapid mitigation of cyanobacterial nuisance

Cyanobacteria blooms are a risk to environmental health and public safety due to the potent toxins certain cyanobacteria can produce. These nuisance organisms can be removed from water bodies by biomass flocculation and sedimentation. Here, we studied the efficacy of combinations of a low dose coagulant (poly-aluminium chloride-PAC-or chitosan) with different ballast compounds (red soil, bauxite, gravel, aluminium modified zeolite and lanthanum modified bentonite) to remove cyanobacterial biomass from water collected in Funil Reservoir (Brazil). We tested the effect of different cyanobacterial biomass concentrations on removal efficiency. We also examined if zeta potential was altered by treatments. Addition of low doses of PAC and chitosan (1±8 mg Al L-1) to the cyanobacterial suspensions caused flock formation, but did not settle the cyanobacteria. When those low dose coagulants were combined with ballast, effective settling in a dose-dependent way up to 99.7% removal of the flocks could be achieved without any effect on the zeta potential and thus without potential membrane damage. Removal efficacy was influenced by the cyanobacterial biomass and at higher biomass more ballast was needed to achieve good removal. The combined coagulant-ballast technique provides a promising alternative to algaecides in lakes, ponds and reservoirs.</p