Seasonal variation in population and community structure of shrews in a tropical forest of Gabon

2005 ◽  
Vol 21 (2) ◽  
pp. 161-169 ◽  
Author(s):  
Violaine Nicolas ◽  
Patrick Barrière ◽  
Marc Colyn
Keyword(s):  
Community Structure ◽  
Seasonal Variation ◽  
Dominant Species ◽  
Abundant Species ◽  
Dry Season ◽  
Reproductive Phenology ◽  
Ecological Constraints ◽  
Species Dominance ◽  
Composition Structure ◽  
Over Time

The composition, structure and reproductive phenology of a shrew community were investigated for 1 y at two neighbouring sites in an undisturbed African forest of south-western Gabon. We captured 717 shrews, belonging to four genera and 10 species. The data were analysed to answer three main questions: (1) to what extent does the shrew abundance vary seasonally? (2) is there a shift in species dominance over time? and (3) does the intensity of breeding activity vary seasonally? The number of species captured varied seasonally and tended to be least during the period of minimal trap success. Trap success for the four most abundant species (Sylvisorex johnstoni, Crocidura batesi, Paracrocidura schoutedeni and Sylvisorex ollula) varied seasonally with a minimum around the long dry season. Sylvisorex johnstoni remained the dominant species throughout the year. Seasonal variation in trap success of shrews might be related, at least partly, to their reproductive characteristics. Litter size, based on embryo counts, ranged from 1–4 among the species. Breeding occurred throughout the year, but its intensity was lower during the long dry season corresponding with the period of higher ecological constraints for shrews.

scholarly journals Contrasting recruitment seasonality of sea urchin species in Gran Canaria, Canary Islands (eastern Atlantic)

2014 ◽  
Vol 15 (3) ◽  
pp. 475 ◽  
Author(s):  
S. GARCIA-SANZ ◽  
P. G. NAVARRO ◽  
F. TUYA
Keyword(s):  
Community Structure ◽  
Seasonal Variation ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Late Summer ◽  
Paracentrotus Lividus ◽  
Abundant Species ◽  
Late Winter ◽  
Gran Canaria ◽  
Arbacia Lixula

Despite sea-urchins can play an important role affecting the community structure of subtidal bottoms, factors controlling the dynamics of sea-urchin populations are still poorly understood. We assessed the seasonal variation in recruitment of three sea-urchin species (Diadema africanum, Paracentrotus lividus and Arbacia lixula) at Gran Canaria Island (eastern Atlantic) via monthly deployment of artificial collectors throughout an entire annual cycle on each of four adjacent habitat patches (seagrasses, sandy patches, ‘urchin-grazed’ barrens and macroalgal-dominated beds) within a shallow coastal landscape. Paracentrotus lividus and A. lixula had exclusively one main recruitment peak in late winter-spring. Diadema africanum recruitment was also seasonal, but recruits appeared in late summer-autumn, particularly on ‘urchin-grazed’ barrens with large abundances of adult conspecifics. In conclusion, this study has demonstrated non-overlapping seasonal recruitment patterns of the less abundant species (P. lividus and A. lixula) with the most conspicuous species (D. africanum) in the study area.

scholarly journals Fish assemblages in a tidal flat

2003 ◽  
Vol 46 (2) ◽  
pp. 233-242 ◽  
Author(s):  
Ana Lúcia Vendel ◽  
Sabine Granado Lopes ◽  
César Santos ◽  
Henry Louis Spach
Keyword(s):  
Cluster Analysis ◽  
Community Structure ◽  
Tidal Flat ◽  
Seasonal Changes ◽  
Dominant Species ◽  
Fish Assemblages ◽  
Seasonal Pattern ◽  
Abundant Species ◽  
Structure Index ◽  
Total Capture

Studies were carried out on fish assemblages in a tidal flat. Samples were obtained monthly at low tide of the half moon in the tidal flat of Paranaguá Bay, Brazil, with two seine nets, one with a 1 mm mesh, 30 m in length and 3 m in height and another with a 10 mm mesh, 65 m in length and 2 m in height. A total of 8,890 fish were captured, comprising 24 families and 53 species. The most abundant species were Harengula clupeola and Atherinella brasiliensis, which represented 63.4% of the total, capture. A seasonal tendency was observed in the abundance of fishes, with less fishes being captured during winter and part of spring. The number of species showed a seasonal pattern, with the gradual decrease through winter and a marked increase in summer. The community structure index indicated seasonal changes in the assemblage. The faunistic similarities between months separated the 12 months into four major groups. The seasonal pattern was apparent in the numerically dominant species and the Cluster Analysis revealed five main groups.

Ants community structure in the urban and the city suburbs areas of Douala (Littoral-Cameroon)

2021 ◽  
Vol 25 (2) ◽  
Author(s):  
BIAWA-KAGMEGNI MIRIC ◽  
FOGUIENG-SAHA DIDIER ◽  
GUETSOP-NGOUADJIE PRUDENCE ◽  
TSEKANE JUNIOR ◽  
FOUELIFACK-NINTIDEM BORIS ◽  
...  
Keyword(s):  
Community Structure ◽  
Human Activities ◽  
Native Species ◽  
Dominant Species ◽  
Invasive Ants ◽  
Species Dominance ◽  
Ant Community ◽  
Littoral Region ◽  
Paratrechina Longicornis ◽  
Tropical America

The Douala harbour represents the main gateway through which human activities introduce invasive ants, so that Solenopsis geminata (Fabricius, 1804) originating from Neotropics has been reported in several areas of the Littoral region of Cameroon. But nothing is known about the ant community structure and composition of the coastal zone. We hypothesized that environmental perturbations around Douala have repercussions on the native litter-dwelling ants. Collections conducted in 33 houses, six gardens of 225 m² each, 41 plantations of one hectare each and 34 two-year old fallows of one hectare each suggested lowly even communities, low species richness, low diversity and low dominance by a few species. Among 28 species recorded four species were mostly represented: two foreign origin species [S. geminata (Fabricius, 1804) and Trichomyrmex destructor (Jerdon, 1851), from tropical America and India respectively], one native species [Pheidole megacephala (Fabricius, 1793)] and two ambiguous native range species [Paratrechina longicornis (Latreille, 1802) and Tapinoma melanocephalum (Fabricius, 1793)] since they have long been recorded as having a widespread distribution. Alien species were highly represented than native ones (52.9% and 47.1% respectively, p<0.001). Inside houses, gardens and plantations the ant species were distributed according to the geometrical progression (Motomura’s model) while in the old fallows abundance distribution suggested an evolved ecosystem (Mandelbrot’s model). Between the three dominant species [Pa. longicornis (Latreille, 1802), Ph. megacephala (Fabricius) and S. geminata (Fabricius)], the first species was positively correlated with the third one while other associations were not significant. These dominant species appeared influencing the abundance of the rare species. Dominance and high abundance of a few species indicated that areas were influenced mostly by interspecies competition and/or disturbance by human activities.

Mesostigmatic mites (Acari: Mesostigmata) in nests of the Eurasian griffon vulture (Gyps fulvus) in Croatia

Biologia ◽  
2011 ◽  
Vol 66 (2) ◽  
Author(s):  
Jerzy Błoszyk ◽  
Tvrtko Dražina ◽  
Dariusz Gwiazdowicz ◽  
Bruce Halliday ◽  
Bartłomiej Gołdyn ◽  
...  
Keyword(s):  
Community Structure ◽  
Species Composition ◽  
Dominant Species ◽  
Bird Species ◽  
Abundant Species ◽  
Birds Of Prey ◽  
Griffon Vulture ◽  
Gyps Fulvus

AbstractWe examined the species composition and community structure of mites of the order Mesostigmata (Acari) in nests of the Eurasian griffon vulture (Gyps fulvus Hablizl, 1783) in Croatia. Material collected from 18 nests included 565 mites belonging to seven species. The most abundant species were Leiodinychus orbicularis (C.L. Koch, 1839) (Trematuridae) and Androlaelaps casalis (Berlese, 1887) (Laelapidae). The results were compared with the community structure and frequency of dominant species of Mesostigmata in nests of 32 other bird species. Leiodinychus orbicularis occurred in the nests of 13 species of birds. It is a typical nidicolous species which occurs most frequently in the perennial nests of birds of prey. In contrast, A. casalis rarely occurs in the nests of birds of prey.

Seasonal variations in population and community structure of small rodents in a tropical forest of Gabon

2003 ◽  
Vol 81 (6) ◽  
pp. 1034-1046 ◽  
Author(s):  
Violaine Nicolas ◽  
Marc Colyn
Keyword(s):  
Seasonal Variations ◽  
Rainy Season ◽  
Abundant Species ◽  
Reproductive Phenology ◽  
Breeding Activity ◽  
Short Rainy Season ◽  
Murid Rodents ◽  
Undisturbed Forest ◽  
Composition Structure ◽  
The Tropics

The composition, structure, and reproductive phenology of a community of murid rodents were investigated for 1 year at two sites in an undisturbed forest in southwestern Gabon, Africa. We captured 1531 mice belonging to 11 species and eight genera. At both sites, species richness varied seasonally and tended to be maximal during the period of maximal trap success. For the most abundant species (Hylomyscus stella, Hybomys univittatus, Heimyscus fumosus, and Praomys cf. misonnei), a general unimodal trend in trap success was detected, owing to variations in breeding activity and survival, with a minimum around the long rainy season and a maximum either during the short rainy season or at the beginning of the following long dry season. These fluctuations varied in magnitude among species, and seasonal variations in relative abundance were recorded. Our results support the assumption that in the tropics, rainfall and associated patterns of fruit and insect abundance are important factors which may act directly or indirectly to initiate breeding activity so that lactation occurs at a time of greatest food abundance. Finally, intrapopulational differences in age at sexual maturity were found, both between the sexes and among individuals of the same sex.

scholarly journals Seasonal variation in the copepod community structure from a tropical Amazon estuary, Northern Brazil

2009 ◽  
Vol 81 (2) ◽  
pp. 187-197 ◽  
Author(s):  
André Magalhães ◽  
Natália da R. Leite ◽  
João G.S. Silva ◽  
Luci C.C. Pereira ◽  
Rauquírio M. da Costa
Keyword(s):  
Community Structure ◽  
Seasonal Variation ◽  
Seasonal Pattern ◽  
Copepod Community ◽  
Water Conductivity ◽  
Species Dominance ◽  
Amazon Estuary ◽  
Density Values ◽  
Clear Seasonal Pattern ◽  
Northern Brazil

The main purpose of this study was to investigate the seasonal variation of copepod community structure during the months of July, September and November 2003 (dry season) and January, March and May 2004 (rainy season) in the Curuçá estuary, northern Brazil. Samples were collected during neap tides via gentle 200µm mesh net tows from a small powerboat. Measurements of surface water conductivity were accomplished in situ using an electronic conductivimeter and salinity was later obtained through the transformation of the conductivity values. Salinity varied seasonally from 7.2 ± 0.1 to 39.2 ± 1.8 (mean ± standard deviation) and was influenced mainly by differences in the amount of rainfall between the studied sampling seasons. In total, 30 Copepoda taxa were identified and Acartia tonsa comprised the most representative species throughout the entire studied period followed by Acartia lilljeborgii, Subeucalanus pileatus and Paracalanus quasimodo. In the present study, the density values, ecological indexes and copepod species dominance presented a clear seasonal pattern, showing that the studied area may be considered seasonally heterogeneous in relation to the investigated parameters.

scholarly journals STRUKTUR KOMUNITAS DAN DISTRIBUSI TEMPORAL GASTROPODA DI DANAU SITU GINTUNG, TANGERANG SELATAN, BANTEN

2017 ◽  
Vol 4 (3) ◽  
pp. 139
Author(s):  
Yayan Mardiansyah Assuyuti ◽  
Alfan Farhan Rijaluddin ◽  
Firdaus Ramadhan ◽  
Reza Bayu Zikrillah ◽  
Dwi Cahya Kusuma
Keyword(s):  
Community Structure ◽  
Seasonal Variation ◽  
Statistical Analysis ◽  
Light Intensity ◽  
Rainy Season ◽  
Dry Season ◽  
Physicochemical Parameter ◽  
Industrial Wastes ◽  
Lake Ecosystem ◽  
Dry And Rainy Seasons

The changes in the physicochemical of waters in the lake ecosystem caused by seasonal variation, anthropogenic and industrial wastes impact the gastropod community. This study aimed to determine the physicochemical parameter of waters, community structure and distribution of gastropod, and the correlation between those two in the dry and rainy seasons. We conducted this research in the lake of Situ Gintung located in Tangerang Selatan, Banten, Indonesia during the dry season (May to August 2015) and the rainy season (February to April 2016). Statistical analysis showed the physicochemical parameter of waters in both seasons has no different, while the gastropod showed a slight difference in occurrence based on the season, in which rainy season had the highest occurrence. Canonical Correspondence Analysis (CCA) suggested that gastropods occurrence were affected by the light intensity in the rainy season and the temperature in the dry season.

scholarly journals Seasonal feeding plasticity can facilitate coexistence of dominant omnivores in Neotropical streams

2021 ◽  
Author(s):  
Mayara P. Neves ◽  
Pavel Kratina ◽  
Rosilene L. Delariva ◽  
J. Iwan Jones ◽  
Clarice B. Fialho
Keyword(s):  
Seasonal Variation ◽  
Fish Species ◽  
Resource Availability ◽  
Seasonal Changes ◽  
Dry Season ◽  
Diet Overlap ◽  
Isotopic Niche ◽  
Neotropical Streams ◽  
Feeding Plasticity ◽  
The Impact

AbstractCoexistence of ecomorphologically similar species in diverse Neotropical ecosystems has been a focus of long-term debate among ecologists and evolutionary biologists. Such coexistence can be promoted by trophic plasticity and seasonal changes in omnivorous feeding. We combined stomach content and stable isotope analyses to determine how seasonal variation in resource availability influences the consumption and assimilation of resources by two syntopic fish species, Psalidodon aff. gymnodontus and P. bifasciatus, in the Lower Iguaçu basin. We also tested the impact of seasonality on trophic niche breadth and diet overlap of these two dominant omnivores. Seasonal changes in resource availability strongly influenced the consumption and assimilation of resources by the two fish species. Both species exhibited high levels of omnivory, characterized by high diversity of allochthonous resources in the wet season. Terrestrial invertebrates were the main component of diet during this season. However, in the dry season, both species reduced their isotopic niches, indicating diet specialization. High diet overlap was observed in both seasons, but the isotopic niche overlap was smaller in the dry season. Substantial reduction in the isotopic niche of P. bifascistus and a shift toward aquatic invertebrates can facilitate coexistence during this season of resource shortage. Feeding plasticity allows omnivorous fish to adjust their trophic niches according to seasonality, promoting the exploitation of different resources during periods of greater resource diversity. This seasonal variation could be an important mechanism that contributes to the resource partitioning and coexistence of dominant omnivores in Neotropical streams.

scholarly journals Seasonal Variation of Rainy and Dry Season Per Capita Water Consumption in Freetown City Sierra Leone

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 499
Author(s):  
Salmatta Ibrahim A ◽  
Fayyaz Ali Memon ◽  
David Butler
Keyword(s):  
Seasonal Variation ◽  
Water Use ◽  
Water Consumption ◽  
Low Income ◽  
Rainy Season ◽  
Predictor Variable ◽  
Dry Season ◽  
Data Set ◽  
Per Capita ◽  
End Use

Ensuring a sustainable urban water supply for developing/low-income countries requires an understanding of the factors affecting water consumption and technical evidence of individual consumption which can be used to design an improved water demand projection. This paper compared dry and rainy season water sources available for consumption and the end-use volume by each person in the different income groups. The study used a questionnaire survey to gather household data for a total of 398 households, which was analysed to develop the relationship between per capita water consumption characteristics: Socio-economic status, demographics, water use behaviour around indoor and outdoor water use activities. In the per capita water consumption patterns of Freetown, a seasonal variation was found: In the rainy season, per capita water consumption was found to be about 7% higher than the consumption for the full sample, whilst in the dry season, per capita water consumption was almost 14% lower than the full survey. The statistical analysis of the data shows that the average per capita water consumption for both households increases with income for informal slum-, low-, middle- and high-income households without piped connection (73, 78, 94 and 112 L/capita/day) and with connection (91, 97, 113 and 133 L/capita/day), respectively. The collected data have been used to develop 20 statistical models using the multiple linear stepwise regression method for selecting the best predictor variable from the data set. It can be seen from the values that the strongest significant relationships of per capita consumption are with the number of occupants (R = −0.728) in the household and time spent to fetch water for use (R = −0.711). Furthermore, the results reveal that the highest fraction of end use is showering (18%), then bathing (16%), followed by toilet use (14%). This is not in agreement with many developing countries where toilet use represents the largest component of indoor end use.

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