scholarly journals Rediscovery of Cameroon Dolphin, the Gulf of Guinea Population of Sousa teuszii (Kükenthal, 1892)

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Isidore Ayissi ◽  
Gabriel Hoinsoudé Segniagbeto ◽  
Koen Van Waerebeek
Keyword(s):  
Shallow Water ◽  
Encounter Rate ◽  
Gulf Of Guinea ◽  
Small Boat ◽  
Sandy Shore ◽  
Western Africa ◽  
Threat Level ◽  
Exploratory Survey

Since the 1892 discovery of the Atlantic humpback dolphin Sousa teuszii (Delphinidae), a species endemic to coastal western Africa, from a skull collected in Cameroon, not a single record has been documented from the country or neighbouring countries. Increasing concern about the continued existence of the Gulf of Guinea population of S. teuszii or “Cameroon dolphin” prompted an exploratory survey in May 2011. Shore-based effort, on foot (30.52 km; 784 min), yielded no observations. Small boat-based surveys (259.1 km; 1008 min) resulted in a single documented sighting of ca. 10 (8–12) Cameroon dolphins in shallow water off an open sandy shore near Bouandjo in Cameroon's South Region. The combination of a low encounter rate of 3.86 individuals (100 km)−1 suggesting low abundance and evidence of both fisheries-caused mortality and of habitat encroachment raises concerns about the Cameroon dolphin's long-term conservation prospect. Our results add to indications concerning several other S. teuszii populations that the IUCN status designation of the species as “Vulnerable” may understate its threat level.

scholarly journals Energy–Vorticity Theory of Ideal Fluid Mechanics

2009 ◽  
Vol 66 (7) ◽  
pp. 2073-2084 ◽  
Author(s):  
Peter Névir ◽  
Matthias Sommer
Keyword(s):  
Fluid Mechanics ◽  
Shallow Water ◽  
Ideal Fluid ◽  
Characteristic Property ◽  
Incompressible Flows ◽  
Climate Simulations ◽  
Shallow Water Models ◽  
Complete Analogy ◽  
Potential Enstrophy

Abstract Nambu field theory, originated by Névir and Blender for incompressible flows, is generalized to establish a unified energy–vorticity theory of ideal fluid mechanics. Using this approach, the degeneracy of the corresponding noncanonical Poisson bracket—a characteristic property of Hamiltonian fluid mechanics—can be replaced by a nondegenerate bracket. An energy–vorticity representation of the quasigeostrophic theory and of multilayer shallow-water models is given, highlighting the fact that potential enstrophy is just as important as energy. The energy–vorticity representation of the hydrostatic adiabatic system on isentropic surfaces can be written in complete analogy to the shallow-water equations using vorticity, divergence, and pseudodensity as prognostic variables. Furthermore, it is shown that the Eulerian equation of motion, the continuity equation, and the first law of thermodynamics, which describe the nonlinear evolution of a 3D compressible, adiabatic, and nonhydrostatic fluid, can be written in Nambu representation. Here, trilinear energy–helicity, energy–mass, and energy–entropy brackets are introduced. In this model the global conservation of Ertel’s potential enstrophy can be interpreted as a super-Casimir functional in phase space. In conclusion, it is argued that on the basis of the energy–vorticity theory of ideal fluid mechanics, new numerical schemes can be constructed, which might be of importance for modeling coherent structures in long-term integrations and climate simulations.

scholarly journals Intercommunity interactions and killings in central chimpanzees (Pan troglodytes troglodytes) from Loango National Park, Gabon

Primates ◽  
2021 ◽  
Author(s):  
Laura Martínez-Íñigo ◽  
Pauline Baas ◽  
Harmonie Klein ◽  
Simone Pika ◽  
Tobias Deschner
Keyword(s):  
Pan Troglodytes ◽  
National Park ◽  
Camera Traps ◽  
Encounter Rate ◽  
Visual Contact ◽  
Intergroup Interactions ◽  
Killing Rate ◽  
The Core ◽  
Pan Troglodytes Troglodytes

AbstractIntercommunity competition in chimpanzees (Pan troglodytes) has been widely studied in eastern (P. t. schweinfurthii) and western (P. t. verus) communities. Both subspecies show hostility towards neighboring communities but differ in rates of lethal attacks and female involvement. However, relatively little is known about the territorial behavior of the two other subspecies, central (P. t. troglodytes) and Nigeria-Cameroon chimpanzees (P. t. ellioti). Here, we present the first insights into intercommunity interactions of individuals of a community of central chimpanzees living in the Loango National Park in Gabon. The presence of individuals of neighboring communities in the Rekambo home range was assessed using 27 camera traps. Information was compiled on intergroup interactions recorded before (2005–2016) and after (January 2017–June 2019) the habituation of the community. Individuals from neighboring communities entered the core area, where nine out of 16 recorded intercommunity encounters occurred. Males were the main participants in territorial patrols and intercommunity aggressions. Females were part of all six territorial patrols recorded and dependent offspring participated in five patrols. Females were involved in intercommunity aggression in five out of twelve recorded encounters in which there was visual contact between communities. While the intercommunity encounter rate was lower than that reported across most other long-term chimpanzee sites, the annual intercommunity killing rate was among the highest. These results suggest that the frequency of lethal attacks at Loango is comparable to that reported for the eastern subspecies. In contrast, female involvement in intercommunity interactions mirrors that of the western subspecies.

A quantitative synthesis of Holocene vegetation change in Nigeria (Western Africa)

The Holocene ◽  
2021 ◽  
pp. 095968362110331
Author(s):  
Matthew Adesanya Adeleye ◽  
Simon Edward Connor ◽  
Simon Graeme Haberle
Keyword(s):  
Vegetation Change ◽  
Climatic Changes ◽  
The Holocene ◽  
Continental Scale ◽  
Western Africa ◽  
Chord Distance ◽  
Quantitative Synthesis ◽  
Climatic Regime ◽  
Pollen Records

Understanding long-term (centennial–millennial scale) ecosystem stability and dynamics are key to sustainable management and conservation of ecosystem processes under the currently changing climate. Fossil pollen records offer the possibility to investigate long-term changes in vegetation composition and diversity on regional and continental scales. Such studies have been conducted in temperate systems, but are underrepresented in the tropics, especially in Africa. This study attempts to synthesize pollen records from Nigeria (tropical western Africa) and nearby regions to quantitatively assess Holocene regional vegetation changes (turnover) and stability under different climatic regimes for the first time. We use the squared chord distance metric (SCD) to assess centennial-scale vegetation turnover in pollen records. Results suggest vegetation in most parts of Nigeria experienced low turnover under a wetter climatic regime (African Humid Period), especially between ~8000 and 5000 cal year BP. In contrast, vegetation turnover increased significantly under the drier climatic regime of the late-Holocene (between ~5000 cal year BP and present), reflecting the imp role of moisture changes in tropical west African vegetation dynamics during the Holocene. Our results are consistent with records of vegetation and climatic changes in other parts of Africa, suggesting the Holocene pattern of vegetation change in Nigeria is a reflection of continental-scale climatic changes.

Development and application of long-term root zone salt balance model for predicting soil salinity in arid shallow water table area

2019 ◽  
Vol 213 ◽  
pp. 486-498 ◽  
Author(s):  
Guanfang Sun ◽  
Yan Zhu ◽  
Ming Ye ◽  
Jinzhong Yang ◽  
Zhongyi Qu ◽  
...  
Keyword(s):  
Shallow Water ◽  
Water Table ◽  
Soil Salinity ◽  
Root Zone ◽  
Balance Model ◽  
Salt Balance ◽  
Shallow Water Table

scholarly journals Sequence of eruptive events in the Vesuvio area recorded in shallow-water Ionian Sea sediments

2008 ◽  
Vol 15 (1) ◽  
pp. 25-32 ◽  
Author(s):  
C. Taricco ◽  
S. Alessio ◽  
G. Vivaldo
Keyword(s):  
Spectral Analysis ◽  
Shallow Water ◽  
Confidence Level ◽  
Statistical Procedure ◽  
Ionian Sea ◽  
High Confidence ◽  
Volcanic Events ◽  
High Confidence Level

Abstract. The dating of the cores we drilled from the Gallipoli terrace in the Gulf of Taranto (Ionian Sea), previously obtained by tephroanalysis, is checked by applying a method to objectively recognize volcanic events. This automatic statistical procedure allows identifying pulse-like features in a series and evaluating quantitatively the confidence level at which the significant peaks are detected. We applied it to the 2000-years-long pyroxenes series of the GT89-3 core, on which the dating is based. The method confirms the dating previously performed by detecting at a high confidence level the peaks originally used and indicates a few possible undocumented eruptions. Moreover, a spectral analysis, focussed on the long-term variability of the pyroxenes series and performed by several advanced methods, reveals that the volcanic pulses are superimposed to a millennial trend and a 400 years oscillation.

Coastal Studies by Sequential Air Photography

1965 ◽  
Vol 19 (4) ◽  
pp. 372-381 ◽  
Author(s):  
H. L. Cameron
Keyword(s):  
Shallow Water ◽  
Systematic Study ◽  
Aerial Photography ◽  
Aerial Photographs ◽  
Current Action ◽  
Coastal Changes ◽  
Air Photo

With the advent of air photography, many problems of mapping coast lines, such as those caused by surf action and underwater obstructions, were solved, as the vertical air photo shows the exact configuration of the coast and reveals many of the shallow-water obstructions. This paper shows that aerial photographs, obtained at intervals ranging from 2 to 20 years, contain important information on long-term coastal changes, brought about by wave and current action over a period of time. Two examples of such changes, revealed by sequential aerial photography, are given. It is concluded that a program of systematic study of existing photographs and supplementary rephotography would more than justify its cost.

scholarly journals Exploratory survey study of long-term users of nicotine replacement therapy in Danish consumers

2015 ◽  
Vol 12 (1) ◽  
pp. 2 ◽  
Author(s):  
Gitte Borup ◽  
Kim Mikkelsen ◽  
Philip Tønnesen ◽  
Lona Christrup
Keyword(s):  
Replacement Therapy ◽  
Nicotine Replacement Therapy ◽  
Survey Study ◽  
Nicotine Replacement ◽  
Exploratory Survey

A new Hispid Beetle injurious to Oil Palms in Brazil

1924 ◽  
Vol 14 (3) ◽  
pp. 245-246 ◽  
Author(s):  
S. Maulik
Keyword(s):  
South America ◽  
West Indies ◽  
Elaeis Guineensis ◽  
Gulf Of Guinea ◽  
The West ◽  
African Lakes ◽  
Western Africa ◽  
Wide Geographical Distribution ◽  
Oil Palms ◽  
African Oil Palm

Through the courtesy of Dr. G. A. K. Marshall, F.R.S., I have had the opportunity of examining the new beetle, a description of which is given below. It was sent by Dr. G. Bondar to Dr. Marshall as occurring in Brazil on Elaeis guineensis. This plant, the African oil palm, is a native of tropical Western Africa, where it has a wide geographical distribution from the Gulf of Guinea to the South of Fernando Po. It flourishes in the Island of Zanzibar and along the shores of the Central African lakes, and has been introduced into the Philippine Islands, the West Indies and South America.

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