Cycle characteristics of planktonic cladocerans in a tropical lake, Central Amazon: Field and experimental work

This thesis is concerned with an investigation into the effects of food concentration, temperature and turbidity on the life cycle characteristics such as growth, body size, development and reproduction of species of planktonic Cladocera brought to the U.K. from a shallow turbid Lake Jacaretinga, Amazonia. The species studied were Daphnia gessneri, Moina reticulata and Diaphanosoma sarsi. Long term growth experiments were performed using both batch and continuous flow culture under controlled laboratory conditions using various combinations of temperature (22&deg;, 27&deg;, and 32&deg;C),concentration of algal food Scenedesmus acutus (0.03, 0.05, 0.1, 0.25, 0.5, and 1.OmgC.1) and turbidity (10, 20, and 50 NTU). Animals were examined daily throughout their cycle from the newborn (neonate) to 3rd adult instars.The ecology of planktonic animals in Lake Jacaretinga was studied intensively during a three month period (February, March and April 1986). This period of study included two ecologically/limnologically important periods, namely, before the flooding of the River Amazon and after the river flooding, when the lake became more turbid due to suspended particles. Weekly samples of zooplankton providedinformation on the species composition and numerical density of the cladoceran populations as well as their horizontal distribution in five stations. Information was also obtained on environmental condition in the lake (Temperature, dissolved oxygen concentration, Secchi disc transparency, chlorophyll-a and particulate carbon concentration.Population of Diaphanosoma sarsi, Ceriodaphnia cornuta and Daphniagessneri, decreased during the flood, and populations of Moinareticulata increased and became a dominant species. Life cycle experiments shows that growth and reproduction are greatly influenced by food concentration and turbidity. Consistent differences were found between Daphnia gessneri and Moina reticulata,being Moina reticulata more successful in survival, growth and reproduction. Application of the experimental results on the effects of food, temperature and turbidity on the life cycle characteristics of the planktonic cladocerans are used to interpret the changes in the cladoceran population in Lake Jacaretinga during this period of floading. This is a significant contribution to our knowledge since Lake Jacaretinga is one of the characteristic varzea lakes in Central Amazonia whose limnology is largely determined by the annual flooding of Amazon River.<p

Composição do zooplâncton em cinco lagos da Amazônia Central

A study of the species composition, satnding-stock and diversity of the zooplancton groups Rotifera. Cladocera and Copepoda. was conducted in five lakes In the Central Amazonian region. The lakes present distinct physical, chemical and biological parameters which allows for distinguishing two groups: On the first group, caracterized by the lakes which present greater concentration of ions, greater availability of nutrients, and greater diversity of zooplancton species are the "várzea" lakes. Castanho, Redondo and Jacaretinga. On the second group, caracterized by the lakes which present low concentrations of ions, few nutrients, and a low diversity of zooplancton species are the "terra-firme" lakes, Cristalino and tarumã-Mirim. The structure of the zooplancton comunities in Amazonian lakes is periodically altered by the inundation of the rivers.O estudo da composição, "standing-stock" e da diversidade do zooplâncton constituído por Rotifera, Cladocera e Copepoda foi realizado em cinco lagos da Amazônia Central. Estes lagos possuem características físicas, químicas e biológicas distintas, o que permite colocá-los em dois grupos1. lagos que apresentam maiores concentrações iônicas, maior disponibilidade de nutrientes e maior diversidade de espécies zooplanctônicas; 2. lagos, com baixa concentração de íons, poucos nutrientes e pequena diversidade de espécies zooplanctônícas. Os lagos colocados no primeiro grupo são os da "várzea" (Castanho, Redondo e Jacaretinga); no segundo grupo, ficam o Cristalino e Tarumã-mirim (lagos de terra firme). A estrutura da comunidade zooplanctônica, nos lagos da Amazônia, é periodicamente alterada pelas inundações dos rios

Nutritional quality of three species of chlorophyceae cultured in the laboratory

Three species of Chlorophyceae algae Scenedesmus quadricauda (Brèbisson, 1835), Ankistrodesmus gracilis (Korsikov, 1953) and Pediastrum duplex (Meyen, 1829), were cultivated in the laboratory, using as a culture medium chemical fertilizer N:P:K in the proportions 20:5:20, respectively. Total chlorophyll-a and organic carbon content were used to evaluate the nutritional values of the three algae. All presented good nutritive values, however, the percentage of carbon versus dry weight was higher in Scenedesmus quadricauda (21%) compared with the other species analysed. The three species were considered to be suitable food for zooplankton.Três espécies de algas clorofíceas, Scenedesmus quadricauda (Brèbisson, 1835), Ankistrodesmus gracilis (Korsikov, 1953) e Pediastrum duplex (Meyen, 1829), foram cultivadas no laboratório, usando como meio de cultura adubo químico N:P:K na proporção 20:5:20, respectivamente. O valor nutricional das algas foi avaliado pela concentração de clorofila-a e pelo carbono orgânico. As três espécies algais apresentaram alto valor nutricional, particularmente Scenedesmus quadricauda, que apresentou a maior percentagem de carbono em relação ao peso seco (21%), sendo considerada como alimento adequado para os organismos filtradores

Methodological Adaptation for Studies "In Situ" of Zooplanktonic Organisms, Applied to Fish Culture

Zooplanktonic organisms play an important role in the feeding of fish larvae, both in nature, and in artificial fish ponds. With the mass culture of zooplankton, the knowledge of important items of the organisms life cycle under different circumstances, can determine the success of the culture. This work shows an adaptation of commercial nursing bottles used in zc \'plankton studies that permits regular investigation of life cycle experiments of zooplanktonic ;rustaceans (Cladocera) in different environments such as: laboratory (immersed in aquariums or not) and "in situ", in fish ponds, or natural environments.Os organismos zooplanctônicos desempenham um importante papel na alimentação de larvas e pós-larvas de peixes, tanto na natureza, como em cativeiro em tanques de piscicultura. No aspecto do cultivo de zooplâncton cm massa, somente conhecendo-se os valores de alguns parâmetros importantes do ciclo de vida de um único indivíduo, em situações diversas, é que se pode avaliar se este estará respondendo de maneira adequada, ou não, a determinado tratamento aplicado. O trabalho mostra uma adaptação de mamadeiras plásticas comerciais para a utilização no estudo individualizado de microcrustáceos zooplanctônicos (cladóceros), em laboratório (aquários), viveiros de piscicultura, ou ambientes naturais (lagos e igarapés)

Zooplankton composition in different environments of the lago camaleão at ilha da Marchantaria, Amazonas state, Brazil

This study aims to verify occurrence and distribution of the major zooplankton groups in three different sub-habitats at Lago Camaleão: channel, aquatic macrophytes and flooded forest, during the high water period (August, 1996). Cladocera, Copepoda and Rotifera occurred with different relative abundances within the three studied environments. In the channel, Cladocera occurred with a high number of species and individuals, Bosminopsis deitersi being the dominant species (89%). Cladocera and Copepoda were equally dominant in the flooded forest, even thought only copepods, nauplius and copepodites immature forms were found. On the macrophytes, Rotifera was the group with the largest occurrence, with the dominance of Lecane quadridentata, Keratella Americana and Brachionus patulus followed by copepods (immature forms) and cladoceres, the latter mostly of the Chydoridae family (21.4%).Este trabalho teve o objetivo de verificar a ocorrência e a distribuição dos principais grupos de zooplâncton em três diferentes sub-habitats do lago Camaleãocanal, macrófitas aquáticas e floresta alagada, no período de cheia (agosto de 1996). Nos três ambientes estudados, Cladocera, Copepoda e Rotifera ocorreram com abundância relativa diferentes. No canal, Cladocera ocorreu com maior número de espécies e de indivíduos, sendo dominante a espécie Bosminopsis deitersi (89%). Na floresta alagada Cladocera e Copepoda foram igualmente dominantes, ressaltando-se que somente ocorreram as formas imaturas de copépodes, náuplios e copepoditos. Nas macrófitas, o grupo de maior ocorrência foi Rotifera, com a dominância de Lecane quadrídentata, Keratella americana e Brachionus patulus seguido de copépodes (formas imaturas) e de cladóceros, estes na maioria da família Chydoridae (21.4%)

Vertical Distribution Of Zooplankton And Physico-Chemical Conditions During A 24-Hour Period In An Amazon Floodplain Lake - Lago Calado, Brazil

In May 1980 Lago Calado was 9 meters deep, the water level was rising slowly, and below 4 meters the water was anoxic. Virtually all of the zooplankton was in the oxygenated layer. Adult and juvenile Daphnia gessneri, the most abundant crustacean species, occurred between 0.5 and 4.5 meters. Copepod nauplii tended to occur nearer to the surface, in the 0-2 meter stratum. No clear vertical migration was observed. The epilimnion was undersaturated ( 2 μ M) and ammonium ( > 5 μ M), but little nitrate ( 2 μ M) e amônia ( > 5 μ M), mas pouco nitrato ( < 0.1 μ M). Um pico de carbono e nitrogênio particulado ocorreu entre 4-5 metros, abaixo da termoclina, associado à um máximo de pigmento

Changes in species composition of Cladocera and food availability in a floodplain lake, Lago Jacaretinga, central Amazon

The Cladocera community, shifted from a complete dominance by Diaphanosoma sarsi, Ceriodaphnia cornuta and Daphnia gessneri, corresponding with the time of low water level, to dominance and density by Moina reticulata with the time of high water level period. -from Autho

Vertical distribution of zooplankton in the water column of Lago Amapá, Rio Branco, Acre, Brazil

O objetivo desta investigação foi observar a distribuição vertical da comunidade do zooplâncton no Lago Amapá (10º2'36S e 67º50'24W), localizado na planície de inundação do Rio Acre. Amostragens foram conduzidas em três diferentes profundidades da coluna da água, considerando aspectos sazonais do zooplâncton, parâmetros físicos, químicos e biológicos. Coletas foram realizadas semanalmente com Garrafa de Van Dorn. As espécies apresentaram maiores concentrações no meio da coluna da água. Foram encontradas 38 espécies, assim distribuídas: Rotifera (30), Cladocera (5) e Cyclopoida (3). A temperatura da coluna da água em geral apresentou-se alta, em torno de 30ºC, com pequena variação, resultando em baixa viscosidade. O índice de Jaccard, comparando-se as três estações de coletas, demonstrou que durante a fase de águas baixas, as estações 1 e 3 foram as mais similares (Cj = 0.7058), especialmente no meio da coluna da água. Lago Amapá apresentou características em conformidade com o Modelo do Distúrbio Intermediário, favorecendo a colonização de grupos oportunistas, tais como rotíferos.The aim of investigation was to study the model of vertical distribution in Lago Amapá, taking into consideration the seasonality of its zooplanktonic composition. Lago Amapá (10º2'36S and 67º50'24W) is located in the floodplain of the Rio Acre. Samplings were conducted at three different depths of the water column, to study the vertical distribution of zooplankton populations and determine some physico-chemical and biological parameters of Lago Amapá. Weekly samples were taken with a Van Dorn sampler. The species showed greater concentrations at the by means of water column. Thirty-eight zooplankton species were found in the samples represented by Rotifera (30), Cladocera (5) and Cyclopoida (3). The temperature of the water column showed a tendency toward relatively high values (about 30ºC) with little variation, consequently resulting in low viscosity. Based of Jaccard's index, it was seen that during the low-water phase, S1 and S3 of the three sampling stations studied, had greater similarity (Cj = 0.7058) in the middle of the water column. Lago Amapá showed characteristics in line with the intermediate disturbance hypothesis model, favoring colonization by opportunistic species such as rotifers

Estimativa do tamanho das fêmeas com ovos de Moina minuta Hansen, 1899 (Cladocera, Crustacea) no lago Amapá, Rio Branco, Estado do Acre Brasil

Moina minuta, a tropical species of Cladocera, was selected for the study of medium size at maturity and female egg production, due to its abundance and frequency in samples during low-water season in 1997 and high-water season in 1998, in Amapá Lake, Western Amazônia. The primiparous female had a size of 330 μm and 340 μm in low and high water, respectively. Moina individuals reached maximum size during high water (595μm). The medium size of the ovigerous females, in low water was 501 μm, producing an average of 4.41 eggs/female, while in high water, it was 533μm, with an average egg production of 4.84 eggs/female. The results, analyzed by the t test and Fischer's F test, showed that there were no statistical differences in size among individuals (t= -10.69, F=1.20 and P>0.1227), nor among ovigerous females (t= -4.45, F=1.02 and P>0.8906), considering the two seasons