scholarly journals Response of phytoplankton to an experimental fish culture in net cages in a subtropical reservoir

2016 ◽  
Vol 76 (4) ◽  
pp. 824-833 ◽  
Author(s):  
E. C. R. Bartozek ◽  
N. C. Bueno ◽  
A. Feiden ◽  
L. C. Rodrigues
Keyword(s):  
Functional Groups ◽  
Seasonal Changes ◽  
Temporal Changes ◽  
Fish Culture ◽  
Experimental Fish ◽  
Phytoplankton Structure ◽  
Nutrients Availability ◽  
Nutrients Concentration ◽  
Abiotic Variables ◽  
Net Cages

Abstract This study aimed to evaluate nutrients concentration and spatial-temporal changes in phytoplankton biovolume during an experimental fish culture in net cages in a lateral arm of Salto Caxias reservoir, Brazil. Two sampling stations were placed in the affected lateral arm and other two in a cageless lateral arm. Neither abiotic variables nor phytoplankton biovolume presented significant differences between the treatments. Only temporal changes were confirmed by the analysis performed. Both lateral arms were classified as oligotrophic, reflecting low influence of the net cages. Phytoplankton growth seems to be limited by nitrogen. Biovolume values were, in general, low and five major functional groups were recognized (E, F, G, K and P). In summer higher biovolume values were observed and representatives of Chlorophyceae and Cyanobacteria belonging to the functional groups F and K, respectively, were the most important. In winter phytoplankton was mainly composed by Bacillariophyceae taxa from P group. G group was also restricted to winter and E group occurred in winter and summer. The variations recorded in phytoplankton structure appear to have been mainly influenced by seasonal changes in temperature, precipitation and nutrients availability. The effects of net cages on the abiotic variables and phytoplankton biovolume appear to have been small, probably due to the small number of net cages employed and the system dilution capacity. However, a permanent monitoring of phytoplankton is recommended, since this environment has a carrying capacity, from which the trophic state may increase.

scholarly journals Seasonal Changes of Nutrient Concentrations in Water of Some Locations in Southern Iraqi Marshes, After Restoration.

2009 ◽  
Vol 6 (4) ◽  
pp. 711-718
Author(s):  
Baghdad Science Journal
Keyword(s):  
Seasonal Changes ◽  
T Test ◽  
Nutrient Concentrations ◽  
P Value ◽  
Statistical Program ◽  
Nutrients Concentration ◽  
Colorimetric Methods

After restoration of Iraqi marshes during 2003, three locations were chosen, one in each main marsh (Um Al-Naaj site in Al-Hwaizeh marsh; Al-Nagarah site in Al-Hammar marsh and Al-Baghdadia site in Al-Chebaysh marsh) to determine the concentrations of nutrients (Nitrate, Nitrite, Phosphate and Silicate) in water seasonally for the period winter, spring, summer, and autumn at 2007. Five water replicates were collected from each site, seasonally. In the Lab., the samples were analyzed by colorimetric methods; the results showed that Um-Al-Naaj site has the highest nutrients level, while Al-Nagarah site has the lowest level. The statistical program t-test was applied at the significant levels (P-value < 0.01) and (P-value < 0.05) to know the significant differences in the nutrients concentration among the sites, as well as among the seasons. Statistically, the results showed that NO3, NO2, and PO4 concentrations have significant differences among the sites, as well as among the seasons. While, SiO2 concentrations have no significant differences among the sites, but they differed significantly among the seasons.

scholarly journals Spatial and temporal changes in fish yields and fish communities in the largest tropical floodplain lake in Asia

2017 ◽  
Vol 53 ◽  
pp. 485-493 ◽  
Author(s):  
Bunyeth Chan ◽  
Peng Bun Ngor ◽  
Nam So ◽  
Sovan Lek
Keyword(s):  
Functional Groups ◽  
Fish Species ◽  
Temporal Changes ◽  
Pangasianodon Hypophthalmus ◽  
Tonle Sap ◽  
Commercial Species ◽  
Fish Catch ◽  
Total Fish ◽  
Spatio Temporal ◽  
Fish Yields

Although the Tonle Sap Lake is the largest natural inland lake in Southeast Asia, little is known about the spatio-temporal patterns of its composition and yields. The present paper aimed to investigate the temporal change of yields of the most dominant fish species and to evaluate the spatio-temporal changes in the fish community and the indicator species of assemblages. Fish catch data were collected from thirty-three fishing lots around the lake during the open season from October to May each year between 1994 and 2000. The fish yields were dominated by few commercial fishes: Channa micropeltes, Pangasianodon hypophthalmus, Channa striata, Cyclocheilichthys enoplos, Henicorhynchus spp., Barbonymus gonionotus, Micronema spp. and Trichopodus microlepis. The standard linear regression coefficients of the fish yields versus year were negative for all these commercial species except T. microlepis. Moreover, the total fish yields of the lake were temporally declined (standard coefficient = −2.410, adjusted r2 = 0.272). Nonmetric multidimensional scaling of the fish assemblage data showed a clear opposition between northern assemblage and southern assemblage along the first axis, and the temporal pattern of the samples from 1994 to 1999 was explained by the second axis. The fish species assemblage from earlier years (1994 and 1995) was characterised by the abundance of all functional groups of black-white-grey fish species, but more recent years (1996–1999) were linked to white and grey functional groups, which was explained by a decrease in many black fishes.

Seasonal changes of functional groups in coleopteran communities in pine forests

2010 ◽  
Vol 19 (8) ◽  
pp. 2291-2305 ◽  
Author(s):  
Won Il Choi ◽  
Kwang-Sik Choi ◽  
Dong-Pyeo Lyu ◽  
Jung-Su Lee ◽  
Jongok Lim ◽  
...  
Keyword(s):  
Functional Groups ◽  
Seasonal Changes ◽  
Pine Forests

Water quality fluctuations under floating net cages for fish culture in Lake Cirata and its impact on fish survival

2005 ◽  
Vol 71 (5) ◽  
pp. 972-977 ◽  
Author(s):  
Irzal EFFENDIE ◽  
Kukuh NIRMALA ◽  
Umar HASAN SAPUTRA ◽  
Agus Oman SUDRAJAT ◽  
Muhammad ZAIRIN ◽  
...  
Keyword(s):  
Water Quality ◽  
Fish Culture ◽  
Net Cages ◽  
Fish Survival

scholarly journals Temporal variation in phytoplankton community in a freshwater coastal lake of southern Brazil

2013 ◽  
Vol 25 (1) ◽  
pp. 99-110 ◽  
Author(s):  
Denise Tonetta ◽  
Mauricio Mello Petrucio ◽  
Roselane Laudares-Silva
Keyword(s):  
Temporal Variation ◽  
Functional Groups ◽  
Phytoplankton Community ◽  
Light Limitation ◽  
Cylindrospermopsis Raciborskii ◽  
Total Density ◽  
Nitrogen And Phosphorus ◽  
Coastal Lake ◽  
Vertical Variation ◽  
Nutrients Availability

AIM: The aim of the present study was to study the vertical variation in phytoplankton community in a subtropical coastal lake and to verify the temporal variation of this community following variation in temperature and dissolved nitrogen and phosphorus. METHODS: Sampling of phytoplankton and abiotic variables were performed monthly from June/2009 to January/2011 at four depths from the central part of Peri Lake. The data were analyzed using analysis of variance, correlation and canonical correspondence analysis. RESULTS: Vertical variation in the phytoplankton community and limnological data did not occur but temporal variation was found. The lake was limited by light and nutrients and this light limitation selected the Cyanobacteria species from Sn and S1 functional groups. Phytoplankton community was composed of five groups, with 31 freshwater taxa, in which Cyanobacteria was the most important with 87.7% of total density and Chlorophyta with 11.8%. Cylindrospermopsis raciborskii was dominant during almost the whole study period because when temperature and phosphorus increased and wind speed decreased Limnothrix sp. density was boosted. Different species of Cyanobacteria filamentous showed correlation with variables in different ways, indicating that some species can co-exist, each of them having distinct niches or can compete by the same resource. CONCLUSION: The phytoplankton presented periodicity driven by annual change in water temperature and nutrients availability. Peri Lake's features allow for the occurrence of a vertically homogeneous water column and the dominance of cyanobacterial functional groups adapted to low underwater light and nutrients deficiency

scholarly journals Phytoplankton functional groups in a tropical reservoir in the Brazilian semiarid region

2017 ◽  
Vol 65 (3) ◽  
pp. 1129
Author(s):  
Ruceline Paiva Melo Lins ◽  
Beatriz Susana Ovruski de Ceballos ◽  
Luiz Carlos Serramo Lopez ◽  
Luciana Gomes Barbosa
Keyword(s):  
Functional Groups ◽  
Environmental Conditions ◽  
Phytoplankton Biomass ◽  
Fish Farming ◽  
Semiarid Region ◽  
Monthly Basis ◽  
Brazilian Semiarid ◽  
Phytoplankton Functional Groups ◽  
Abiotic Variables ◽  
Density And Biomass

Phytoplankton functional groups structure and species abundance vary according to environmental conditions. The present study investigated the natural and anthropogenic stressors that affect phytoplankton functional group biomass in a Brazilian semiarid region reservoir (Argemiro de Figueiredo reservoir). Sampling occurred between August 2007 and July 2009 on a bi-monthly basis for the first year, and in a monthly basis for the last two years. There were three collection points (PC: river confluence; PNC: near the cages; PD: dam site). The water environment analysis of abiotic variables included: temperature, transparency, coefficient of vertical light attenuation, dissolved oxygen, pH, electrical conductivity, alkalinity, dissolved inorganic nitrogen, and reactive soluble phosphorus. Phytoplankton samples were collected into a Van Dorn bottle, and were then preserved in acetic lugol and were quantified using an inverted microscope to determine phytoplankton density and biomass; the identified species were assembled in functional groups. The data were explored by canonical correspondence analysis. Individual analyses were made to test the temporal and spatial variability of the data and the factors that interfered most with the biotic and abiotic variables. Functional groups S1, SN, and K, consisting of filamentous Planktothrix agardhii (Gomont) Anagnostidis & Komárek, Cylindrospermopsis raciborskii (Woloszynska) Seenaya & Subba Raju, and the coccoid Aphanocapsa incerta (Lemmermann) Cronberg & Komárek, respectively, dominated the dry months when the water was warm, turbid, and alkaline. The overflow reservoir served as a natural disturbance reducing the phytoplankton biomass to less than 50 % and the dominance of cyanobacteria, promoting the domain of functional groups F, M, MP, Lo, and X2. The nutrient inputs from intensive fish farming, associated with a low local depth (Zmax = 7.7 m) close to the cages (PNC), resulted in a significant human disturbance that increased the prevalence of functional groups S1, SN, and K, which are composed primarily of cyanobacteria. We concluded that, in reservoirs, overflow events are natural disturbances that have the ability to reduce phytoplankton biomass and alter the structure of local communities, and that intensive fish farming is an anthropogenic disturbance that increases the availability of nutrients and stimulates an increase in biomass of the functional groups that include cyanobacteria. Furthermore, the functional groups of phytoplankton were reliable control of environmental conditions in the reservoirs of tropical semiarid regions.

scholarly journals Structural changes of the phytoplankton and epiphyton in an urban hypereutrophic reservoir

2016 ◽  
Vol 28 (0) ◽  
Author(s):  
Lucineide Maria Santana ◽  
Carla Ferragut
Keyword(s):  
Species Richness ◽  
Water Flow ◽  
Structural Changes ◽  
Light Availability ◽  
Temporal Changes ◽  
Nutrient Concentrations ◽  
Nitrogen And Phosphorus ◽  
Nutrients Availability ◽  
High Species Richness ◽  
Different Depths

Abstract: Aim This study evaluated the temporal changes of phytoplankton and epiphyton structure and their relationships with limnological factors in an urban hypereutrophic reservoir (Rasgão Reservoir, Brazil). Methods We collected water sample and phytoplankton in different depths at two sites (dam and near tributary input) in summer and winter 2010. Epiphyton on Salvinia spp. was sampled only at site near the tributary input. We determined limnological variables and structural attributes (species composition, density, biovolume, descriptors species, diversity) for both communities. Results Phytoplankton density and epiphyton density and biovolume were higher in the winter (dry season), which occurred the higher nutrient concentrations and lower water flow. Chlorophyceae was dominant in the phytoplankton in both period and Cyanobacteria was the second most abundant class in the winter. In the epiphyton, Bacillariophyceae was dominant in the summer and Cyanobacteria in the winter. The increase in light availability and water flow can have provided high species richness and diversity in the summer. Conclusion Temporal changes in the structure of phytoplankton and epiphyton on Salvinia were more related to increased nutrients availability (nitrogen and phosphorus) and flow variations in a hypereutrophic reservoir.

Temporal changes in a demersal fish and cephalopod community of an unexploited coastal area in Northern Australia

1984 ◽  
Vol 35 (6) ◽  
pp. 747 ◽  
Author(s):  
SF Rainer
Keyword(s):  
Water Temperature ◽  
Seasonal Changes ◽  
Fish Community ◽  
Demersal Fish ◽  
Temporal Changes ◽  
Tropical Fish ◽  
Trawl Survey ◽  
Depth Range ◽  
Local Abundance ◽  
Different Seasons

A trawl survey of the south-eastern Gulf of Carpentaria carried out at the beginning of a commercial prawn fishery in the 1960s provided data on the demersal fish of an unexploited tropical fish community. The extent of temporal variation in this community was investigated using abundance data on 359 taxa of fish and cephalopods over 13 months in 1963-1964. Seasonal changes in water temperature and salinity were large, particularly in nearshore waters. Catch rates and species richness in nearshore waters were highest during summer, and in offshore waters during autumn or winter. Shannon diversity was variable, with no clear seasonal component. Temporal changes in community composition resulted in large changes between different seasons in the structure of site groups derived by classification; temporal effects within seasons were also found. The numerically dominant species were the leatherjackets Paramonacanthus spp., the ponyfish Equulites leuciscus, the tripodfish Tripodichthys blochii, and the saury Saurida undosquamis. Squid, the ponyfish Leiognathus sp. nr blochi, the butterfly-bream Nemipterus tolu and the grunter Pomadasys maculatus were seasonally abundant. Although species were restricted in their depth range, discrete communities that maintained their identity in different seasons were apparently absent. The relative abundance of many species varied substantially wirh season and probably also over a longer period. Small changes in local abundance were often associated with movement to deeper water at times of high nearshore water temperature (summer) or of reduced nearshore salinity (autumn). Large seasonal changes occurred in the local abundance of estuarine and semidiadromous species. The community shared many species with the demersal fish community of the Gulf of Thailand. It is suggested that similar structural changes in the fish community of the Gulf of Carpentaria may occur in response to intensive fishing. Further research on the effects of demersal fishing and on the interactions of the demersal fish community with commercially important crustaceans is necessary.

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