Danmarks rotifera : I. grundtraekkene i rotiferenes okologi, morfologi og systematik.

Thesis (doctoral)--Kobenhavn.

Plankton periodicity and some physicochemical parameters of the intake channel of Lake Chad

This study examines zooplankton periodicity and some physicochemical parameters of the intake channel of Lake Chad (Nigeria). Nine different zooplankton species were identified at the sampling station 1, while seven different zooplankton species were identified at the sampling station 2 (the intake channel of Lake Chad). Each identified zooplankton species was grouped according to its major group of copepods, Cladocera or Rotifera. The copepods dominated the zooplankton community with the highest numbers of occurrence as Cyclopedia species throughout the course of the study at both station l and 2. There was a clear evidence of the influence of organic manure nutrients on total zooplankton population at station 1 when compared to that of station 2. The water quality variables measured in the course of this study show that the surface water temperature in station 1 ranges from 27.5 degree C to 30.5 degree C. The pH ranges from 6.8 to 8.5, while D.O. contents ranges from 2.9mg/L to 6.1mg/L and alkalinity recorded was 172.00 to 208.00. At the station 2 the water quality parameters obtained show that surface water temperature ranges from 27.3 degree C to 30.2 degree C, pH ranges between 6.9 to 8.5, while the D.O contents ranges from 3.0 mg/L to 6.2 mg/L.Alkalinity ranges from 172mg/L to 212 mg/L

Zooplankton-fish interactions in the littoral zone of Nyanza Gulf, Lake Victoria

Samples of zooplankton and fish were collected from six sampling points in Nyanza Gulf, Lake Victoria in Kenya from June to December 1998, using 76 mu m memo-filament mesh size strainer and an 80 mu m mesh size plankton net. Identification and enumeration were done in the laboratory. Occurrence, numerical and points methods were used in stomach anlaysis of fish. Copepoda, Rotifera and Cladocera were the major zooplankton groups identified, zooplankton such as Moina, Daphnia and Caridina nilotica were important prey items for Lates niloticus, Oreochromis niloticus and Rastrineobola argentea

The relationship between some physicochemical parameters and plankton composition on fish production in ponds

The effect of physico-chemical parameters and plankton composition on fish production in ponds was investigated in six fish farms for eight weeks. The physicochemical parameters investigated were temperature=25-30 plus or minus C, transparency=0.45-0.57m, dissolved oxygen=3.0-10.9mg/l, pH=6.0-7.7, dissolved carbon dioxide=5.46-28.3mg/l, total alkalinity=44.37-80.0ppm, chemical oxygen demand=31.88-72.18mg/l and biological oxygen demand=0.66-48.34mg/l. Plankton composition varies and was made of four families of phytoplankton namely; Cyanophyceae, Chlorophyceae, Dinophyceae and Diatomida; and four families of zooplankton viz; Protozoa, Rotifera, Copepoda and Dinoflagellates. Farm 1 and 6 recorded the highest average weight of about 1.0kg and average total length of about 40.0cm for the two fish species. This study showed that fish yield was dependable on the quality and management of pond water characteristics

Some aspects of the limnology of Makwaye (Ahmadu Bello University) Lake, Samaru, Zaria

The monthly variations in the physico-chemical parameters and zooplankton abundance were followed from December, 2003 to March 2004 in Makwaye (Ahmadu Bello University Farm) Lake, Samaru, Zaria. In this lake, all physico-chemical parameters investigated showed wide variations within the months except hardness, which exhibited highly significant variation both between stations and within months. Chemical variables including Na, Mg, Zn, Pb, Fe, K and Cu showed significant variations within the months. Three groups namely Cladocera (32.62%), Rotifera (29.33%) and Copepoda (38.05%) were observed. These indicated low species richness

The relationship between some physicochemical parameters and plankton composition on fish production in ponds

The effect of physico-chemical parameters and plankton composition on fish production in ponds was investigated in six fish farms for eight weeks. The physicochemical parameters investigated were temperature=25-30 plus or minus C, transparency=0.45-0.57m, dissolved oxygen=3.0-10.9mg/l, pH=6.0-7.7, dissolved carbon dioxide=5.46-28.3mg/l, total alkalinity=44.37-80.0ppm, chemical oxygen demand=31.88-72.18mg/l and biological oxygen demand=0.66-48.34mg/l. Plankton composition varies and was made of four families of phytoplankton namely: Cyanophyceae, Chlorophyceae, Dinophyceae and Diatomida; and four families of zooplankton viz: Protozoa, Rotifera, Copepoda and Dinoflagellates. Farm 1 and 6 recorded the highest average weight of about 1.0kg and average total length of about 40.0cm for the two fish species. This study showed that fish yield was dependable on the quality and management of pond water characteristics

Plankton associated with medusae of the freshwater jellyfish Craspedacusta sowerbyi (Lankester) in a Thames backwater

Samples of plankton were taken from Broom Water in August 1997 after a sighting of medusae on 11th August. Broom Water is about 8 m wide, and extends 250 m from the main channel of the Thames, above the weir at Teddington. On 11th August medusae were so abundant that it was possible to collect 20 in ten minutes. They were rising to the surface in bright sunlight, then sinking slowly down through the water. Examination of a medusa's tentacles under a microscope revealed the presence of a commensal protozoan, a ciliate Trichodina pediculus. Over 20 species of phytoplankton were found in Broom Water. Most of the species are common and widespread, but it was a surprise to find Errerella bornhemiensis with its characteristic pyramidal colonies, which is a relatively rare species. Zooplankters in Broom Water consisted of Rotifera and Crustacea. Zooplankton is the main food of Craspedacusta and it was found that the crustaceans but not the rotifers did undergo significant changes during the period 11-19th August. The major changes were a big increase in the percentage of cyclopoids, and a marked decrease in Bosmina. This could be because the delicate cuticle of Bosmina is much more susceptible to the stinging cells of the medusae compared with the tougher exoskeleton of the cyclopoid.

Feeding selectivity of brown trout (Salmo trutta) in Loch Ness, Scotland

The aim of this study was to compare statistically the zooplankton assemblage ingested by brown trout (Salmo trutta) in Loch Ness with that of the zooplankton in the water column. This would allow the examination of the apparent paradox that very few copepods appear to be consumed by trout at a time of year when they are numerous and readily available as food. The investigation was limited to the crustacean zooplankters, since the Rotifera are generally so small that they are only of interest to fish in the first few days of life. 25 trout were obtained from anglers, and the stomach contents of non-"ferox" animals analysed. Samples of pelagic zooplankton were obtained approximately monthly from 30-m vertical net-hauls (mesh size 100 km). It is concluded that the variation in dietary composition with trout wet weight indicates an ontogenetic habitat shift producing spatial separation of young and older individuals.

The zooplankton species composition and abundance in Ogun River, Abeokuta, Ogun State, southwestern Nigeria

Investigation on the species composition and abundance of zooplankton in Ogun River, Abeokuta, Ogun state, Southwestern Nigeria was carried out for a period of seven months (December, 2011-June, 2012), Using hand trawling method, 55 µm mesh size plankton net was trawled horizontally ten times to capture zooplankton. The zooplankton samples were put into properly labeled plastic containers and preserved in 4% formalin solution. A total of sixteen genera from five taxonomic groups were recorded from Ogun River. Cladocera predominated both in terms of species composition and abundance. Five species of Cladocera was recorded consisting of 31.25%. Protozoa and Rotifera recorded four species each consisting of 25%. Copepoda recorded two species consisting of 12.5%, and Ostracoda with one species consisting of 6.25%. The low nature of zooplankton abundance and species composition observed in this study must have been caused by the polluted nature of the water due to the anthropogenic activities carried out around its shores The dominance of Cladocera in this river is similar to findings from River Echara and River Imo, Southeastern Nigeria.

Seasonal variation in the occurrence of some zooplankton in a fish pond

Observations were made on the seasonal variation in the occurrence of some zooplankton in a fish pond. A total of 31 genera were recorded, out of these, 8 belongs to Rotifera, 5 to Copepoda, 112 to Cladocera, 3 to Protozoa, 2 to Nematoda and 1 to Oligochaeta. The role of temperature, dissolved oxygen, free Co2, pH, turbidity and alkalinity in the occurrence of different genera is discussed.

A guide to the freshwater fauna of Ceylon. Supplement 3

This supplement to the “Guide to the freshwater fauna of Ceylon” by A. S. Mendis and C. H. Fernando. Bull Fish. Res. Stn. Ceylon 12, 160 pp. (1962) includes a number of additional records to the fauna and nomenclatural changes designed to bring the names of the Rotifera, and Hydracarina up to date. This latter involves a complete change in naming of Rotifera to keep in line with modern nomenclature synonymizing species where necessary. A major study on the water mites of India by Cook (1067) has necessitated considerable changes in the naming of Ceylonese species. Besides the Rotifera and Hydracarina the Ilemiptera-Heteroptera have received attention as regards the Corixidae and new generic and specific records from published and unpublished material has been included. A major difficulty in studying freshwater animals (for that matter any animals) is the lack of suitable illustrations of local forms. An attempt has been made to fill this gap for the Rotifera and Turbellaria, It is hoped that in future supplements other groups can be similarly dealt with.

The freshwater zooplankton of Sri Lanka, with a discussion of tropical freshwater zooplankton composition

Based on the study of over 500 zooplankton samples collected in Sri Lanka during 1965-1974, the species composition from different habitats is analysed. The zooplankton assemblage is typically tropical with relatively few species of Cladocera and Copepoda. The Rotifera include a large number of species of the genus Brachionus. The limnetic zooplankton resembles the pond zooplankton closely in that all the eurytopic species found in the different types of habitats, including ponds; also occur in the limnetic zooplankton. The large Cladocera belonging to the genus Daphnia are very rare. In general, large zooplankters are absent. The size composition of the zooplankton has a smaller range than in temperate regions. This is due to the absence of large-sized zooplankton species. The reasons for the differences in species variety and size composition between zooplankton of temperate and tropical regions is perhaps due to a number of factors. These include the effects of high and uniform temperatures, food availability and predation by fish and invertebrates.

Size related feeding patterns and electivity indices of silver barb (Barbodes gonionotus Bleeker) from a pond, Bangladesh

The feeding patterns with respect to quality and quantity of food of silver barb, Barbodes gonionotus varied with their size and development. The results indicated that the fish in the size group I (7-25 mm TL) were fairly omnivore with particular liking for rotifera, green and blue-green algae while the size group II (25.1-44 mm TL) and III (44.1-55 mm TL) were omnivore with higher tendency of feeding on debris, aquatic plants, green algae, blue-green algae and rotifera. However, the fish of the size group IV (55.1-80 mm TL) were found to be herbivore with feeding preference for aquatic plants, green and blue-green algae. In all the size groups, debris was the most dominant food item. Feeding preference of the fish showed clear ontogenetic shift. The electivity indices revealed that the fish were selective feeder.

Food and feeding habit of chapila (Gudusia chapra)

Abundance of diatom (Bacillariophyceae) in the plankton population and the dietary role of it in chapila (Gudusia chapra) in pond were studied. A total of 25 genera of phytoplankton belonging to Bacillariophyceae (7), Chlorophyceae (11), Cyanophyceae (5) and Euglenophyceae (2) and 9 genera of zooplankton belonging to Crustacea (3) and Rotifera (6) were recorded from the water. Among the phytoplankton, highest abundance of Chlorophyceae was observed, and Bacillariophyceae, Cyanophyceae and Euglenophyceae ranked the second, third and fourth position in the planktonic population, respectively. Among the zooplankton, Rotifera was recorded as the most dominant group and Crustacea as the least one. From the gut content analysis, 4 groups of phytoplankton consisting of 33 genera of plankton were identified and recoded [sic] of which 25 belonging to phytoplankton and 8 belonging to zooplankton. This study reveals that the Chlorophyceae and Cyanophyceae were the most dominant food items of chapila. Bacillariophyceae (diatom) and Euglenophyceae were less important and Crustacea and Rotifera were the least important in the diet of Chapila. The present investigation showed that chapila appeared to be a plankton feeder with a preference for phytoplankton to zooplankton. Electivity analysis showed that the fish avoided zooplankton and strongly selected phytoplankton. In the gut contents of fish, Chlorophyceae was positively and Bacillariophyceae (diatom) was negatively selected throughout the experimental period, in the pond water.

Effects of control of C/N ratio by low-cost carbohydrate addition on water quality and pond ecology in freshwater prawn Macrobrachium rosenbergii post-larvae nursing system

An experiment was conducted to evaluate the effects of control of carbon/nitrogen ratio (C/N ratio) by addition of low cost carbohydrate to the water column on water quality and pond ecology in freshwater prawn Macrobrachium rosenbergii post-larvae nursing system. In this experiment, two level of dietary protein 20% and 35% without carbohydrate addition (‘P20' and ‘P35') and with carbohydrate addition (‘P20+CH' and ‘P35+CH') were compared in small ponds of 40 m² area stocked with 20 post-larvae (0.021 ± 0.001g) per m² . Maize flour was used as low cost carbohydrate and applied to the water column followed by the first feeding during the day. The addition of carbohydrate significantly reduced (p< 0.05) ammonia-nitrogen (NH sub(3)-N) and nitrite-nitrogen (NO sub(2) - N) of water in P20 + CH and P35 + CH treatments. It significantly increased (p< 0.05) the total heterotrophic bacteria (THB) population both in water and sediment. Fifty nine genera of plankton were identified belonging to the Bacillariophyceae (11), Chlorophyceae (21), Cyanophyceae (7), Dinophyceae (1), Rotifera (7) and Crustacea (9) without any significant difference (p>0.05) of total phytoplankton and zooplankton among the treatments. Survival rate of prawn was significantly lowest (p<0.05) in P20 and no significant difference (p>0.05) was observed between P20+CH and P35 treatments. Control of C/N ratio by the addition of low-cost carbohydrate to the pond water column benefited the freshwater prawn nursing practices in three ways (1) increased heterotrophic bacterial growth supplying bacterial protein augment the prawn post-larvae growth performances, (2) reduced demand for supplemental feed protein and subsequent reduction in feed cost and (3) reduced toxic NH sub(3)-N and NO sub(2)-N levels in pond nursing system.