Composition and distribution of dragonflies and damselflies (Insecta: Odonata) in Iloyin Forest, Akure, Southwestern Nigeria

Odonate fauna of Iloyin Forest was studied from October to December 2009 to have an overview of the species composition and distribution with the threat of deforestation in the area. Adult species were collected once a week using a sweep net throughout the period of the study from three study sites (denoted as I, II and III) with varying levels of anthropogenic disturbance. A total of 76 species belonging to eight families were recorded in the forest. The two most abundant families in the forest were the Libellulidae (Anisoptera) and Coenagrionidae (Zygoptera).  Palpolpeura portia, P. lucia and Congothemis dubia were the dominant species of Libellulidae, while Pseudagrion kersteni was the dominant coenagrionid.   Some species of Odonata usually associated with shaded forests were encountered in two of the study sites. The highest diversity and evenness indices were recorded at Site I, followed by Site II and the least recorded at Site III. Although shade-loving species recorded in the study area was an indication of its richness in forest Odonata, some may have however become locally endangered or extinct as a result of deforestation. A check in the rate of deforestation could preserve the few forest (endangered) species and restore the locally extinct ones that changed habitats. Key Words:     Biodiversity, Conservation, Disturbance, Forest, Freshwater, Odonat

Rapid survey of Dragonflies (Insecta: Odonata) of Kribi forest and Campo Ma'am national Park, Southern Cameroon

A five day survey was carried out to assess the odonate fauna associated with the riverine sections of two forests (Kribi Forest and Campo Ma’am National Park) of southern Cameroon. The primary objective of the study was to determine the species composition and community structure of the odonate fauna occurring in the forests. The goal is to infer the health status of the two forests. Three study sites were selected, one in each of the main water bodies in the forests (Rivers Kienke and Linde in Kribi forest, and River Bitande in Campo Ma’am National Park). All the specimens collected were identified to the lowest taxonomic level. A total of one hundred and ninety four (194) individuals of Odonata were collected in the forests comprising 10 families, 24 species of Anisoptera and 30 species of Zygoptera. Anthropogenic activities were less prevalent at Campo Ma’am National Park, an area in which all the 10 families were incidentally recorded.The community structure of the southern forest revealed that only River Bitande with Shannon-Wiener diversity index (H`) of 3.80 was having a stable environmental condition. Others were close to stable condition (River Kienke H` 2.99 and River Linde H` 2.95) with mild disturbance caused by human activity. Simpson index range (0.94 – 0.98) at the three study sites revealed that the vegetation was matured and stable. The distribution of dragonflies and damselflies revealed a stable environment (Evenness 0.90 – 0.95). Kribi Forest appears to be more impacted by anthropogenic activities as fewer (six) families were recorded there. The relative distribution of the species in the two forest ecosystems seemed to have some relationship with human interference therein. Key Words: Damselfly, Dragonfly, Diversity, Forest, Rive

Preliminary limnological survey of Ori stream, Iwo, Osun State, Nigeria

Ori stream (one of the tributaries of River Oba, Iwo, Osun State, Nigeria) was studied from October to December 2013 with the aim of providing baseline information on its water quality, phytoplankton primary productivity and invertebrate faunal composition. Plankton samples were collected by towing plankton net over a 2 metres horizontal distance, while benthic macroinvertebrate samples were collected by kick-sampling technique. Hydrological and some physico-chemical variables were  determined in-situ, and water samples collected for further physico-chemical analyses in the laboratory. A total of 17 phytoplankton species, seven species of zooplankton and eight species of benthic  macroinvertebrates were recorded. The upper reach of the stream was the most polluted with the presence of biological indicators of poor water quality, while the lower reach recorded some biological indicators of good water quality. Although the upper reach recorded the highest gross primary productivity, the highest net primary productivity was recorded at the stream’s lower reach. Water quality typically decreased from the upper  reach of the stream towards the middle reach but later picked up at the lower reach before discharging into River Oba. The physico-chemical and biotic nature of the different reaches were a reflection of human activities in and around the stream. Keywords: Benthic macroinvertebrates, conservation, headwater stream, plankton; primary productivity, water quality

Localization and broadband follow-up of the gravitational-wave transient GW150914

A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter we describe the low-latency analysis of the GW data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network circulars, giving an overview of the participating facilities, the GW sky localization coverage, the timeline, and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic (EM) signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the EM data and results of the EM follow-up campaign are being disseminated in papers by the individual teams

Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees

Consistent patterns of common species across tropical tree communities

Trees structure the Earth's most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1-6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth's 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world's most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees

Localization and broadband follow-up of the gravitational-wave transient GW150914

A gravitational-wave transient was identified in data recorded by the Advanced LIGO detectors on 2015 September 14. The event candidate, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter we describe the low-latency analysis of the gravitational wave data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network Circulars, giving an overview of the participating facilities, the gravitational wave sky localization coverage, the timeline and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the electromagnetic data and results of the electromagnetic follow-up campaign will be disseminated in the papers of the individual teams

Hydrology and water quality characteristics of a stressed lotic freshwater system in southwest Nigeria

The hydrology and water quality of Aiba stream were investigated from November 2012 to April 2013 on monthly basis. This was with a view to assessing the status of the stream sequel to its last study which indicated a poor physico-chemical water quality. Four sampling stations were established for the study along the longitudinal axis of the stream, covering both the upper and lower reaches. Hydrological input from the upstream reservoir was observed to be considerably low during the dry season, a situation which further exacerbated the water quality as indicated by very low dissolved oxygen concentration, high BOD5, high conductivity value and high ionic concentrations. High nutrient (PO43- and NO3-) level recorded in this study indicated a eutrophic freshwater system. Generally, the physico-chemical nature of the water in the dry season indicated that the stream fell short of the standards required for freshwater life. Urgent steps need to be taken to mitigate the impacts of natural and man-induced stresses on the stream in order to safeguard the ecosystem and the surrounding terrestrial ecosystems.Keywords: channel width, discharge, flow velocity, hydrological characteristics, lotic system, spatio-temporal, stress, water qualit