scholarly journals Annual Pattern on Abundance and Sex Ratio Distribution of Selected Fish Fauna of Ikere Gorge Reservoir, Oyo State, Nigeria

2019 ◽  
Vol 9 (1) ◽  
pp. 1-13
Author(s):  
Festus Idowu Adeosun
Keyword(s):  
Sex Ratio ◽  
Fish Fauna ◽  
Diversity Indices ◽  
Fish Population ◽  
Dry Season ◽  
Fish Diversity ◽  
Wet Season ◽  
Ratio Distribution ◽  
Significant Difference ◽  
Catch Composition

Sex ratio affects the growth of wild population, thus, with the declining wild fish population, the study was designed to determine the effect of seasons on the sex ratio of fish population from Ikere Gorge, Nigeria for 18 months. Fish composition, diversity, distribution and abundance were determined according to standard methods. Sexes were determined and sex ratio was calculated using a standard method. A total of 5,823 fish specimens were caught during the period. The captured fish species were identified and classified into 34 species belonging to 13 families. The species richness was higher in the dry months than in the wet months. Fish diversity indices and evenness revealed a better diverse and even ecosystem in the wet season than the dry season. A marked significant difference (p < 0.05) was observed between the species in the dry months than the wet season. Chrysichthyes nigrodigitatus (35.07±7.59a) was significantly (p < 0.05) more abundant than the other species in the dry season. The sex ratio was skewed in favour of the female populations for C. nigrodigitatus, Tilapia melanopleura and Sarotherodon galilaeus but the reverse was the case for L. niloticus population. No monthly variation was observed in sex ratio of the species. The fish fauna from Ikere Gorge showed marked variations in the catch composition between the dry and wet months. C. nigrodigitatus and the Cichlids (Hemichromis fasciatus, S. galilaeus, Tilapia macrocephla and T. melanopleura) were present all year.

scholarly journals Ground survey of red lechwe in the Linyanti swamps and Chobe floodplains, northern Botswana

Koedoe ◽  
2017 ◽  
Vol 59 (2) ◽  
Author(s):  
Phemelo Gadimang ◽  
Gaseitsiwe S. Masunga
Keyword(s):  
Sex Ratio ◽  
Age Structure ◽  
National Park ◽  
Local Communities ◽  
Dry Season ◽  
Wet Season ◽  
Seasonal Shift ◽  
Ground Survey ◽  
Significant Difference ◽  
Tourism Potential

A ground survey of red lechwe was carried out in the Linyanti swamps and the Chobe floodplains of northern Botswana in the dry and wet seasons of 2012 and 2013, respectively. We documented numbers, sex ratio and age structure of red lechwe within the linear strips of 25 km × 300 m along the Linyanti swamps and the Chobe floodplains. Results indicated a significant difference in the numbers of red lechwe between sites and seasons. About 66 and 755 red lechwe were estimated for Chobe in the dry and wet season, respectively, with 343 and 261 of them estimated for Linyanti in the dry and wet season, respectively. In Chobe, the red lechwe densities varied widely between seasons (9 red lechwe/km2 – 101 red lechwe/km2 ) compared with Linyanti, where the densities did not vary much between seasons (35 red lechwe/km2 – 46 red lechwe/km2 ). The lower densities of red lechwe in Chobe in the dry season when compared with the wet season suggest a possible seasonal shift in the distribution of red lechwe to the nearby Zambezi floodplains in Namibia.Conservation implications: The higher number of red lechwe in the Chobe floodplains in the wet season indicates the potential of the floodplains as a habitat for this species in that season. The dry season shift in the distribution of red lechwe in Chobe presents an opportunity for local communities in Namibia to engage in tourism, whereas the return of the red lechwe to the floodplains in the wet season ensures protection of the animals as well as boosts the tourism potential of the Chobe National Park.

scholarly journals Environmental Variables and Ecological Distribution of Ichthyofauna Assemblages in the Calabar River, Nigeria: Present and Future Prospects

2016 ◽  
Vol 74 (4) ◽  
pp. 159-171
Author(s):  
Andem Bassey Andem ◽  
Sunday Ben Ekanem ◽  
Esien Ene Oku
Keyword(s):  
Surface Water ◽  
Water Temperature ◽  
Environmental Variables ◽  
Fish Fauna ◽  
Dry Season ◽  
Fish Diversity ◽  
Surface Water Temperature ◽  
Future Prospects ◽  
Ecological Distribution ◽  
Wet Season

Abstract Studies on environmental variables and ecological distribution of ichthyofauna assemblages were conducted in the Calabar River. Surface water and ichthyofauna were sampled in order to provide baseline or reference data on the Calabar River at present as regard its future prospects. Seasonal variation shows significant differences in surface water temperature, pH, DO, BOD, conductivity, TDS and TSS between sampling stations and insignificant differences in heavy metals such as cadmium, chromium, iron and copper between sampling stations. Twenty six species of fish fauna were identified belonging to twenty two families. Mugilidae, Clariidae, Cichlidae, Gobiidae and Sciaenidae were the most abundant for both wet and dry season, while Clupeidae, Bathyclupeidae, Carangidae and Sphyraenidae were low in the wet season but high in the dry season. Chromium, copper, surface water temperature, DO correlate significantly with the presence of E. fimbriata, B. soporator, M. sebae, C. gariepinus, M. loennbergii, C. guentheri and P. babarus. The overall values of biotic diversity indices ranged from 0.0504-0.0745 for Simpson’s Index, 2.770-3.095 for Shannon Index, 2.821-3.105 for Margalef’s Index and 0.8606-0.9498 for equitability. However, the presence of certain fish fauna in polluted and non-polluted parts of the river indicates that they could be used as potential bioindicators in assessment and biomonitoring of the river. The methods used in identifying fish diversity proved their applicability for future studies.

scholarly journals KOMPOSISI DAN FLUKTUASI HASIL TANGKAPAN TUGUK DI SUNGAI LEMPUING, SUMATERA SELATAN

2017 ◽  
Vol 15 (2) ◽  
pp. 105
Author(s):  
Dharmadi Dharmadi ◽  
Endi Setiadi Kartamihardja ◽  
Agus Djoko Utomo ◽  
Dian Oktaviani
Keyword(s):  
Fish Species ◽  
Descriptive Analysis ◽  
Dry Season ◽  
Survey Method ◽  
Wet Season ◽  
River Waters ◽  
Transition Season ◽  
Fish Catch ◽  
Catch Composition ◽  
Mystus Nemurus

Tujuan penelitian ini adalah untuk mengetahui komposisi dan fluktuasi hasil tangkapan tuguk pada periode berbeda yang dioperasikan di Sungai Lempuing, Sumatera Selatan. Kegiatan penelitian dilaksanakan dengan metode survei pada periode musim peralihan penghujan sampai dengan kemarau (bulan April), musim kemarau (bulan Juni) dan musim penghujan (bulan Desember) tahun 2007. Komposisi jenis ikan dan hasil tangkapan diperoleh berdasarkan pada data pengambilan contoh pada saat ke lapangan dan data harian hasil tangkapan tuguk yang dicatat oleh 3 orang enumerator. Data dianalisis secara deskriptif. Hasil penelitian menunjukkan bahwa hasil tangkapan tuguk berbeda menurut periode waktu. Hasil tangkapan terdiri atas 11 jenis ikan untuk musim peralihan dan kemarau masing-masing berkisar 400-450 kg per unit per hari (rata-rata 411,2+14,1 kg per unit per hari) dan 250-300 kg per unit per hari (rata-rata 263,3+13,4 kg per unit per hari) dan 13 jenis ikan pada musim penghujan (bulan Desember) berkisar 700-750 kg per unit per hari (rata-rata 724,8+17,7 kg per unit per hari). Hasil tangkapan didominansi oleh jenis ikan lele (Clarias melanoderma) dan baung (Mystus nemurus). Selama penelitian, kandungan oksigen terlarut di perairan relatif rendah, berkisar 2-4 mg per l, namun dapat ditolelir oleh kelompok jenis ikan rawa (black fish). This research proposed to observed a catch composition and fluctuation of filtering device in different periods operated in the Lempuing River, South Sumatera. The research was conducted using survey method at a respective month of April (transition season), June (dry season) and December 07 (wet season). Fish composition and catch of tuguk were noted during survey and based on recording 3 enumerators. Descriptive analysis was used in this study. The results show that the catch of filtering device differed on diferent season periodes. A number of 11 fish species was caught at a respective season of transition season (April) of 400-450 kg per unit per day (average=411.2+14,1 kg per unit per day), dry season (June) of 250 300 kg per unit per day (average = 263,3+13,4 kg per unit per day), whilst at rainy season (December), fish catch composed of 13 fish species, ranging 700-750 kg per unit per day or (average = 724.8+17.7 kg per unit per day). Clarias melanoderma and Mystus nemurus were dominantly caught in the Lempuing River waters. During observation, dissolved oxygen content was relatively low (2-4 mg per l), that but could be tolerated by black fish.

scholarly journals Effect of introduced species and habitat alteration on the occurrence and distribution of euryhaline fishes in fresh- and brackish-water habitats on Aruba, Bonaire and Curaçao (South Caribbean)

2008 ◽  
Vol 77 (1) ◽  
pp. 45-51 ◽  
Author(s):  
H. Hulsman ◽  
R. Vonk ◽  
M. Aliabadian ◽  
A.O. Debrot ◽  
V. Nijman
Keyword(s):  
Fish Species ◽  
Poecilia Reticulata ◽  
Fish Fauna ◽  
Hierarchical Cluster ◽  
First Record ◽  
Dry Season ◽  
Indigenous Species ◽  
Wet Season ◽  
Netherlands Antilles ◽  
Induced Changes

We conducted an ichthyological survey during the dry season of 2006 on the semi-arid islands of Aruba, Bonaire and Curaçao to provide information on species composition, richness and distribution in natural and non-natural aquatic habitats. The dry season species assemblages (N = 9 species) comprised less species than the wet seasons, and these data refine our knowledge of the indigenous fish fauna and its refuge localities during phases of drought and ensuing high salinity. A hierarchical cluster analysis reveals that the three islands have different species compositions with Curaçao being the most diverse, probably due to its having the most habitats and freshwaters present throughout the year. Species richness was unrelated to salinity and species diversity was highest in canalised streams. In the dry season fewer amphidromous species are present than in the wet season. We found no significant effect of human-induced changes on the presence or absence of fish species in the Netherlands Antilles. The presence of exotic species (including Xiphophorus helleri on Aruba, a first record for this island, and Oreochromis mossambicus and Poecilia reticulata occurring on all three islands) did not have a clear effect on the presence of indigenous species, nor did human alteration of the habitats have an influence on the occurrence of fish species.

scholarly journals Seasonality of Mansonia titillans during dam construction, Biritiba-Mirim, São Paulo State, Brazil

2013 ◽  
Vol 13 (1) ◽  
pp. 70-73 ◽  
Author(s):  
Frederico Alves D'Avila ◽  
Almério de Castro Gomes
Keyword(s):  
Early Spring ◽  
Dry Season ◽  
Southeastern Brazil ◽  
Rank Test ◽  
Late Winter ◽  
Dam Construction ◽  
Wet Season ◽  
Paulo State ◽  
Significant Difference ◽  
Wilcoxon Rank Test

A two and a half year survey was conducted at a dam in southeastern Brazil. Shannon Traps were used for sampling. Kruskal-Wallis test showed little relation between rainfall and abundance. The data clearly show three abundance peaks, all of them in the end of the dry season, in consonance with the scarce literature existent. Although Kruskal-Wallis Test did not find a clear preference for the dry season, Pairwise Wilcoxon Rank Test revealed a significant difference between Fall and Spring samples. Ma. titillans population had a peak on late winter/early spring, close to the begin of wet season.

scholarly journals THE EFFECT OF SEASONAL VARIATION ON PERFORMANCE OF EGG TYPE POULTRY: A Case Study of Mitchell Farms, Mosogar, Delta State, Nigeria

2021 ◽  
Vol 24 (2) ◽  
pp. 101-105
Author(s):  
E. E. Guobadia
Keyword(s):  
Seasonal Variation ◽  
Feed Intake ◽  
Egg Production ◽  
Management Practices ◽  
Secondary Data ◽  
Dry Season ◽  
Wet Season ◽  
Egg Hatchability ◽  
Significant Difference

The study was designed to find out the effect of seasonal variation on poultry in Delta State of Nigeria. The variables considered were mortality rate, feed intake, egg production and egg hatchability in the wet and dry seasons of the year. Secondary data were also collected from records kept in the farm. Sites 4AHI-BLK,5AKI-BLK, 9H/BF and 10H/BF were used for the study with each having an average of 2,500-3,500 birds of the same breed and sex aged 1-9 weeks and 21-52weeks. The records were grouped into dry season (October-March) and wet season (April-September) covering three years, 1991-1994. The analysis of the result showed that seasonal variation does not have any significant effect (P < 0.05) on mortality and feed intake in the two seasons. However percentage egg production and egg hatchability revealed a significant difference (P < 0.05) between the two seasons, with a mean % egg production and hatchability of 74±.03 and 80.6 in the wet season and 53.67±0.01 and 55.9 respectively in the dry season. Recommendation is therefore made for proper planning which ensures the utilization of wet and dry season management practices to reduce the effect of high humidity and embient temperature on production.

Home-range and den use of the mahogany glider, Petaurus gracilis

2000 ◽  
Vol 27 (1) ◽  
pp. 49 ◽  
Author(s):  
Stephen M. Jackson
Keyword(s):  
Home Range ◽  
Dry Season ◽  
Home Ranges ◽  
Adjacent Area ◽  
Wet Season ◽  
Male And Female ◽  
Fragmented Habitat ◽  
Significant Difference ◽  
Socially Monogamous ◽  
Males And Females

The home-range of the mahogany glider was estimated, and its social behaviour examined, by following radio-collared animals over a two-year period within an area of continuous habitat and an adjacent area of fragmented habitat. The average home range within the continuous habitat was 19.25 ha for males and 20.34 ha for females, with male and female pairs occupying a combined area of 23.15 ha. In contrast, the average home range in the fragmented habitat was 11.05 ha for males and 6.80 ha for females, with a combined home-range of male and female pairs being 11.60 ha. The average overlap of the home ranges of paired males and females was 85.9%, compared with approximately 11% for non-paired individuals, which suggests that mahogany gliders are socially monogamous. For a total of 46 nights on which gliders were considered to behave normally for the entire night, the average foraging distance was 1506 m (range 590–3420 m) with no significant difference between males and females in either the continuous or fragmented habitat. There was, however, a significant difference in the distance individuals travelled during different times of the year, with longer distances being travelled during late dry season/wet season and shorter distances during the early to mid dry season. Mahogany gliders also travelled further when there was a high availability of nectar and pollen than when there was lower availability. A total of 83 dens (tree hollows) were recorded for the mahogany glider, with the poplar gum, Eucalyptus platyphylla, forest red gum, Eucalyptus tereticornis, and Clarkson's bloodwood, Corymbia clarksoniana, being most used.

Population density, development and behaviour of Diopsis longicornis and D. apicalis (Diptera: Diopsidae) on rice in the Republic of Guinée

1993 ◽  
Vol 83 (1) ◽  
pp. 5-13 ◽  
Author(s):  
H. Chiasson ◽  
S.B. Hill
Keyword(s):  
Dry Season ◽  
Wet Season ◽  
African Countries ◽  
Planting Dates ◽  
Transplanted Rice ◽  
Significant Difference ◽  
Important Pest ◽  
Direct Seeded ◽  
The Republic ◽  
Diopsis Longicornis

AbstractThe behaviour and pest status of the rice stem borers Diopsis longicornis Macquart and D. apicalis Dalman were investigated in the Republic of Guinée, particularly during the dry season. The variables were direct seeded and transplanted rice, and three (1988, 1989) and four (1987) planting dates. Transplanted rice was damaged nearly three times more than direct seeded rice in the dry season, but no significant difference was detected during the wet season. As previously observed in other West African countries, D.apicalis only occasionally damages rice in Guinée. Contrary to findings elsewhere, D. longicornis was not an important pest of Guinean rice, infesting only 5% and 3% of stems over the three dry and the two wet seasons, respectively. However, year round rice production could promote build up of the diopsid population if dry season planting is not sufficiently delayed (45 days) after the last rains of the wet season.

Trypanosome infection rates inGlossina morsitans submorsitansNewst. in Northern Nigeria

1964 ◽  
Vol 55 (2) ◽  
pp. 219-231 ◽  
Author(s):  
A. M. Jordan
Keyword(s):  
Infection Rate ◽  
Dry Season ◽  
Tsetse Fly ◽  
Effect Of Temperature ◽  
General Effect ◽  
Northern Nigeria ◽  
Trypanosome Infection ◽  
Infection Rates ◽  
Wet Season ◽  
Significant Difference

Previous records and new data on trypanosome infection rates inGlossina morsitans submorsitansNewst. in Northern Nigeria are presented, and discussed in relation to the hosts fed on by this tsetse fly. The new observations were carried out in three areas: at Mando and Gamagira, both lying in a fly-belt north of Kaduna, and in the Yankari Game Reserve in Bauchi Province.Infection rates were obtained by dissection of flies, and the trypanosomes were identified by their locus; the validity of this method of identification is discussed. All infections withTrypanosomaspp. were attributable either to thevivaxgroup or to theconrgolensegroup; nobrucen-group trypanosomes were identified. More than 260 flies from each area were examined during March 1962, at the end of the dry season, and similar numbers during October 1962, at the end of the wet season.There was no significant difference between dry-season and wet-season infection rates in any area. Taking the two seasons together, the rate at Yankari (12%) was significantly higher than the rates at Mando (5%) and Gamagira (3%), which did not differ significantly. These contrasting infection rates could be related to the host species principally fed on by flies in the different areas as shown by blood-meal determinations. The lowest infection rates occurred where Suidae furnished a high proportion of meals (Mando, 51%; Gamagira, 67%) and Bovidae a small proportion (Mando, 16%; Gamagira, 9%). The high infection rate at Yankari was associated with a high proportion of Bovid meals (53%), especially from buffalo (Syncerus nanus) and bushbuck (Tragelaphus scriptus), and a lower proportion of Suid meals (33%). For the three areas the relationship between infection rate and percentage of Bovid meals was statistically significant.The species groups of infecting trypanosomes showed further contrasts between the three areas which were unrelated to the total infection rates. At Gamagira, 81 per cent, of infections werecongolensegroup, and this proportion was significantly higher than that at Mando (45%) or Yankari (37%). The differences could be related to the types of host from which blood-meals were principally derived. The highest proportion ofcongolense-group infections occurred where the highest percentage of meals came from Suidae (Gamagira, 67%), and lower proportions occurred at Mando and Yankari where Suid feeds were relatively fewer (51% and 33%, respectively).These findings are discussed in the light of existing evidence on the factors governing infection rates inGlossina. It is concluded that, within the over-riding influence exerted by temperature through geographical latitude, infection rates are determined by the type of host that forms the principal source of food. In some populations of Glossina the influence of the nature of the main food source can be sufficient to obscure the general effect of temperature in determining the level of infection. Some of the reasons for these relationships are discussed.

scholarly journals The effect of different pasture management strategies in north-west Queensland on liveweight gain and wool growth rate of several groups of young sheep.

1985 ◽  
Vol 7 (2) ◽  
pp. 75 ◽  
Author(s):  
RGA Stephenson ◽  
DA Pritchard ◽  
PM Pepper ◽  
PT Connelly
Keyword(s):  
Growth Rate ◽  
Dry Matter ◽  
Management Strategies ◽  
Live Weight ◽  
Dry Season ◽  
Wet Season ◽  
Pasture Management ◽  
North West ◽  
Wool Growth ◽  
Significant Difference

The effect of three different pasture management strategies on liveweight gain and wool growth rate of young(weaner) sheep was examined immediately after weaning on Mitchell grass-Flinders grass pastures during the dry season of north-west Queensland. The pasture management strategies were designed to mimic various industry situations, while the performance of four different progeny groups was compared and used to provide an overall assessment of pasture quality. Pasture treatments (experiment 1) consisted of three paddocks, a harvested (c. 8% of pasture harvested and baled) and spelled, a spelled, and a continuously grazed paddock. Spelled paddocks were not grazed during and after the wet season for a period of six months while the continuously grazed paddock was continuously stocked before the experiment. Experiment 2 consisted of spelled and continuously grazed paddocks. Pastures were evaluated by measuring the changes in composition and quality (experiment 1) and the responses in liveweight gain (experiments 1 and 2) and wool growth of the weaners (experiment 1). Marked improvements (c. 100%) in weaner growth rates occurred in the spelled paddocks. Greasy wool production by three groups of ewes in experiment I was about 14% greater in the harvested paddock than in the others. At the start of the trial there were no significant differences in dry matter yield but a significant difference in botanical composition occurred between paddocks. The changes in dry matter that occurred between the beginning and end of grazing were not significantly different between paddocks. Before gazing, forbs made up approximately 16%, 4% and 1% of pastures in harvested, spelled and continuously grazed paddocks respectively. The change in the percentage forbs that occurred between the beginning and end of the grazing period was significantly greater in the harvested paddock than in the other paddocks indicating preferential selection and intake by sheep. The differences in weaner live weight and wool growth between paddocks suggest that paddock management can improve weaner productivity. The study also indicates that paddock management could be successfully used to increase the percentage of forbs and quality of the pasture during the dry season. The superior wool growth of two progeny groups also suggests that improved productivity of breeding flocks in the tropics is possible if superior sheep can be identified. The results highlight the importance of preferential management of pasture for weaners so that productivity advantages can be exploited.

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