Mercury and persistent organic pollutant concentrations in African fish eagles, marabou storks, and Nile tilapia in Uganda

The purpose of this research was to evaluate persistent organic pollutant (POP) and mercury concentrations in tissues of African fish eagles (Haliaeetus vocifer) and Nile tilapia (Oreochromis niloticus) from Lake Victoria near Entebbe and Lake Mburo, Uganda. Marabou stork (Leptoptilos crumeniferus) nestlings from urban Kampala (40 km from Entebbe) also were sampled for POPs and mercury. Total mercury was measured in the breast feathers of eight nestling and 10 adult African fish eagles from Lake Mburo, 10 nestling and five adult African fish eagles from Lake Victoria near Entebbe, and 20 nestling marabou storks from Kampala from June 2002 through January 2003. Mercury concentrations in all samples were below levels associated with adverse effects in similar species. Mercury concentrations were significantly higher in eagle adults and nestlings from Entebbe than in adults and nestlings from Lake Mburo (P< or =0.05). No significant differences (P> or =0.05) were found in mercury concentrations between sexes or between the entire fish eagle population sampled at Entebbe and marabou stork nestlings sampled at nearby Kampala. Plasma samples from the same birds were analyzed for 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane, aldrin, hexachlorocyclohexane (alpha-HCH), dieldrin, endrin, heptachlor and their metabolites, as well as total polychlorinated biphenyls (PCBs). Nile tilapia whole-body cross sections collected from Lake Mburo (n=3) and Lake Victoria near Entebbe (n=8) also were analyzed for these POPs and mercury. No samples contained POPs or PCBs at the limits of detection except for 4,4'-1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene in five adult eagle plasma samples (0.0026+/-0.0015 ppm wet weight) and five Nile tilapia samples (0.002+/-0.001 ppm wet weight) from Entebbe.     

Nestling growth in the African fish eagle in Uganda

Nestling African fish eagles Haliaeetus vocifer (Daudin, 1858) in Queen Elizabeth National Park (QEP), Uganda, attained and exceeded the adult body weights of their respective sexes by fledging time. The growth curves conformed with the sigmoid form of most animal species. The overall growth rate, K (g/day), was low, averaging 0.077 ± 0.017 g/day and the time t_10–90 required to complete growth from 10 to 90% of the asymptotic weight was c. 42 days. Brood size and hatching order did not significantly influence growth rates but the sex of the young did. The tarsus, femur and humerus reached adult sizes by fledging time but the standard wing did not.     

Clinical pathology of nestling marabou storks in Uganda

Packed cell volumes (PCV) and plasma chemistry parameters were measured in 20 nestling marabou storks (Leptoptilos crumeniferus) in January 2003 that were a part of a colony located in the center of the city of Kampala, Uganda. There were no significant differences (P> or =0.05) in plasma chemistry values or PCV between sexes with the exception of globulin and total plasma protein values, which were higher in females. There were significant differences (P< or =0.05) in blood glucose, creatine kinase, and globulin levels between birds of different body weight. Total plasma protein, uric acid, phosphorous, and creatine kinase were generally higher relative to published data on other avian species, including nestling white storks (Ciconia ciconia).     

Contribution of molecular phylogeny and morphometrics to the systematics of African elephants

African elephants are conventionally classified as a single species: Loxodonta africana (Blumenbach 1797). However, the discovery in 1900 of a smaller form of the African elephant, spread throughout the equatorial belt of this land, has given rise to a debate over the relevance of a second species of elephant in Africa. The twentieth century has not provided any definite answer to this question. Actually, recent molecular analyses have sustained this issue by advocating either a division of forest elephants into a valid species, or their inclusion as a subspecies of L. africana. Our work initiated at the National Museum of Natural History of Paris provides new molecular (mitochondrial) and morphological (and morphometrical) evidence making it possible to propose a comprehensive phylogenetic hypothesis. It appears that there is no conclusive argument to keep forest elephants (cyclotis form) and savannah elephants (africana form) apart in two distinct species. A high level of mitochondrial introgression between the two forms, as well as a continuum in the morphology of the skulls of the two morphotypes rather suggests that, despite an ancient division, these two taxa freely interbreed wherever their ranges intersect. We thus adopt a conservative systematic position in considering these two forms as two subspecies, respectively: L. africana africana, the savannah elephant, and L. africana cyclotis, the forest elephant. We finally discuss the conservation topic in the light of this systematic framework.     

Gill morphometrics of two Antarctic fish species Pleuragramma antarcticum and Notothenia gibberifrons

Summary Gill dimensions of 27 juvenile and adult Pleuragramma antarcticum from the southern Weddell Sea and of 28 juvenile and adult Notothenia gibberifrons from the South Orkney and South Shetland Islands were estimated. The unit gill area (UGA) of P. antarcticum ranged from 75 to 167 mm²/g (mean=105); gill area index (GAI) and water-blood distance (WBD) were found to be 1.38 cm² and 3.3 m, respectively. The exponent d_g in the relationship total gill area to weight was found to be 0.90. It is concluded that P. antarcticum belongs to sluggish species and, although pelagic, its routine energy costs tend to be low. However, the closely packed lamellae (NL/mm=21) indicate more active behaviour in comparison with N. gibberifrons. A preliminary estimation of growth parameters (P, k) is presented. The sluggish behaviour of N. gibberifrons, as expected from its benthic mode of life, is reflected by the gill parameters: the very low UGA ranged from 39 to 118 mm²/g; GAI and d_g were found to be 0.73 cm² and 0.98, respectively. Comparing gill dimensions and general respiration characteristics of fish from antarctic, temperate and tropical waters it is concluded that antarctic fish have increased their scope for activity.     

Resource partitioning by Lake Tana barbs predicted from fish morphometrics and prey characteristics

We develop a food-fish model (FFM), whichquantitatively relates properties of aquaticfood types (size, shape, escape velocity,habitat, mechanical properties and chemicalquality) to feeding structures of cyprinidfish. The model is based on functionalmorphology and experiments on search, capture,selection, and internal processing of food byfish. The FFM shows which food properties aremost critical in feeding and how fish canoptimise coping with them. Relative food sizeimposes the highest demands, followed by preyvelocity, food habitat and mechanicalproperties. These overrule taxonomic affinitiesof food types. Highly demanding food types(large, fast prey, suspensions of plankton,benthic prey and mechanically tough items)impose incompatible morphological requirementson fish. We apply the FFM to the endemic Barbus species flock of Lake Tana (Ethiopia),since the structural diversity of its 14species reflects recent adaptations to trophicniches. We predict their potentials inutilising different food types by quantitativecomparisons of 35 parameters, measured for eachspecies, with the values for each foodspecialist derived from the FFM. These dietpredictions are tested against gut contentsfrom 4,711 fish, sampled over seasons andhabitats. Gut contents and predictions show agood overall fit. The value of the model isshown by its resolution in predicting resourcepartitioning among the barbs. For the 14 barbsa trophic hierarchy with six major trophicgroups is reconstructed which closely matchesthe predictions. Trophic specialists (> 65%by volume of a single food type) are alsostructurally specialised, whereas less extremeanatomical structures characterise trophicgeneralists, allowing them to switch betweenfeeding modes. Trophic generalists are bestdefined by behavioral flexibility, sincefeeding modes integrate both fish and foodcharacters. The FFM is of practical use inevaluating the role of morphological diversityin an ecosystem and enables the analysis oftrophic interactions in fish communities and ofthe cascading effects by environmental change.Such an approach can be instrumental in thedevelopment of management strategies forfisheries and in conservation of biodiversity.     

Territory size and distribution in the African fish eagle

The fish eagles along 32 km of shoreline were counted regularly from a launch. The territory size was found to be 0.6 km of shore with a density of 3.5 eagles per km. A single aerial count along 323 km of shore returned a density of 1.9 eagles per km with a territory size of 1.0 km of shore. The distribution of fish eagles is related to the relative availability of trees as perches and probably also to the abundance of fish. The quantity of fish taken by the fish eagles is shown to be negligible compared either with the total production or with the yield harvested by man.     

Chytrid fungus in frogs from an equatorial African montane forest in western Uganda

Batrachochytrium dendrobatidis, the causative agent of chytridiomycosis, was found in 24 of 109 (22%) frogs from Kibale National Park, western Uganda, in January and June 2006, representing the first account of the fungus in six species and in Uganda. The presence of B. dendrobatidis in an equatorial African montane forest raises conservation concerns, considering the high amphibian diversity and endemism characteristic of such areas and their ecological similarity to other regions of the world experiencing anuran declines linked to chytridiomycosis.     

Survey for hemoparasites in imperial eagles (Aquila heliaca), steppe eagles (Aquila nipalensis), and white-tailed sea eagles (Haliaeetus albicilla) from Kazakhstan

Prevalence of hemoparasites has been investigated in many avian species throughout Europe and North America. Basic hematologic surveys are the first step toward evaluating whether host-parasite prevalences observed in North America and Europe occur elsewhere in the world. We collected blood smears from 94 nestling imperial eagles (Aquila heliaca), five nestling steppe eagles (Aquila nipalensis), and 14 nestling white-tailed sea eagles (Haliaeetus albicilla) at Naurzum Zapovednik (Naurzum National Nature Reserve) in Kazakhstan during the summers of 1999 and 2000. In 1999, six of 29 imperial eagles were infected with Lencocytozoon toddi. Five of 65 imperial eagles and one of 14 white-tailed sea eagle were infected with L. toddi in 2000. Furthermore, in 2000, one of 65 imperial eagles was infected with Haemoproteus sp. We found no parasites in steppe eagles in either year, and no bird had multiple-species infections. These data are important because few hematologic studies of these eagle species have been conducted.