Overlap in utilization of juvenile Cape Horse Mackerel by Cape Fur Seals and the purse-seine fishery in Namibia

The Cape horse mackerel Trachurus trachurus capensisis one of Namibia's most valuable fish stocks, and an important component to the diet of Cape fur seals, Arctocephalus pusillus pusillus, off northern Namibia. The level of overlap in the utilization of this resource between seals and the purse-seine fishery was investigated using two overlap indices. For high overlap measures, seals and the purse-seine fishery utilized age-2 horse mackerel. For low overlap measures, seals mainly consumed age-0 fish whereas the fishery caught age-2 fish. Both indices were adjusted by the proportion of horse mackerel in the seal diet, with the assumption that the proportion consumed by the seals reflects the abundance of horse mackerel in the coastal waters of Cape Cross, Namibia. Both unadjusted and adjusted overlap indices showed that overlap between seals and the fishery in their utilization of juvenile horse mackerel was high only at times when horse mackerel abundance was high, and low when abundance was small. Confidence intervals and significance testing were included. Overall, there was little overlap between seals and the purse-seine fishery. This study provides important information that should be taken into account in the management of the horse mackerel resource

Roles of spatial scale and rarity on the relationship between butterfly species richness and human density in South Africa

Wildlife and humans tend to prefer the same productive environments, yet high human densities often lead to reduced biodiversity. Species richness is often positively correlated with human population density at broad scales, but this correlation could also be caused by unequal sampling effort leading to higher species tallies in areas of dense human activity. We examined the relationships between butterfly species richness and human population density at five spatial resolutions ranging from 2′ to 60′ across South Africa. We used atlas-type data and spatial interpolation techniques aimed at reducing the effect of unequal spatial sampling. Our results confirm the general positive correlation between total species richness and human population density. Contrary to our expectations, the strength of this positive correlation did not weaken at finer spatial resolutions. The patterns observed using total species richness were driven mostly by common species. The richness of threatened and restricted range species was not correlated to human population density. None of the correlations we examined were particularly strong, with much unexplained variance remaining, suggesting that the overlap between butterflies and humans is not strong compared to other factors not accounted for in our analyses. Special consideration needs to be made regarding conservation goals and variables used when investigating the overlap between species and humans for biodiversity conservation

Steroidogenic potential of the ovary, placenta and blood of the rock hyrax (procavia capensis)

Circulating progesterone, Sα-dihydroprogesterone and oestradiol-17β concentrations, and the biosynthetic potential of blood, ovaries and placenta incubated with pregnenolone and progesterone in the absence and presence of β-NADPH, enzyme inhibitors and at various incubation times, was determined for pregnant and non-pregnant hyraxes. Plasma concentrations of 5α dihydroprogesterone were higher than those of progesterone and appear to be metabolically derived from progesterone in the blood of female hyraxes. Plasma concentrations of oestradiol- l7β were low. White blood cells metabolised pregnenolone and progesterone, and whole blood, red blood cells and a mixture of red and white blood cells metabolised only progesterone. Plasma had no biosynthetic potential. All conversions in the blood resulted in the production of compounds A and B, partially identified as 5α- and 5β-reduced metabolites of progesterone. Progesterone metabolism was highest in pregnant animals and the formation of conversion products was lowest during latepregnancy. White blood cells displayed the highest steroidogenic activity, which may be inhibited or negligible in blood. Whole blood had the lowest biosynthetic potential and this may be due to the presence of enzyme inhibitors or progesterone binding proteins in the plasma. Luteal, ovarian residual and placental tissues metabolised both pregnenolone and progesterone. Compound E, formed by luteal tissue, has been identified as 17α-hydroxyprogesterone and compound F, formed by ovarian residual tissue, has been partially identified as 17α-hydroxyprogesterone. Compound H was formed by placental tissue and has been partially identified as 20a-dihydroprogesterone. Luteal tissue may be important for the production and secretion of progesterone into the circulation. Pregnenolone metabolism increased in the presence of B-NADPH as well as with a longer incubation time, and was inhibited by NaF-HgCl.Dissertation (MSc (Zoology))--University of Pretoria, 1998.Zoology and EntomologyMSc (Zoology)Unrestricte

The diet of the Cape fur seal Arctocephalus pusillus pusillus in Namibia : variability and fishery interactions

Includes bibliographical references

Karoo BioGaps project – butterfly survey results and their interpretation

The Karoo BioGaps project (KBGP) data acquisition phase was executed between March 2016 and December 2018. Butterfly surveyors made 82 visits to 46 survey sites, selected statistically to represent the types of habitats found in the Karoo. 600 species records were made of 101 species and 262 DNA samples were collected. The data have been analysed to compare expected butterfly occurrence with the actual observations; identify new quarter degree grid square species records and new species records for the entire KBGP study region; assess the impact of the new data on the Red List status of selected butterfly taxa; identify the butterfly functional types found in the Karoo; determine the average species richness in the Karoo vegetation types and biomes; and assess the impact of rainfall and veld condition on species richness. Recommendations are made to improve the efficiency of data acquisition in future surveys in the Karoo

Notes on the life history of Epitoxis namaqua de Freina & Mey, 2011 (Lepidoptera: Erebidae: Arctiinae: Syntomini)

The final-instar larva and pupa of the South African Syntomini species Epitoxis namaqua de Freina & Mey are described and illustrated, and the life history of the species from egg to adult is illustrated. Notes are given on the habitats, host-plants and distribution of the species. Photographs are provided of the holo- and paratypes and of the male genitalia and antennae in comparison with those of E. amazoula (Boisduval, 1847), the type species of Epitoxis Wallengren (1863)

South African Environmental Observation Network: vision, design and status

The South African Environmental Observation Network (SAEON), which has its origins in the scientific community, has evolved significantly over the last five years. Core government support for this emerging initiative became a reality in 2002, when the first funding commitment was made. The establishment of an ambitious distributed national environmental observation system requires extensive partnership arrangements, ranging from participating government departments, through numerous institutions and the corporate sector, to the active individual researchers. In its first three years, SAEON has established its credentials within the South African scientific community, created and staffed a national office at the National Research Foundation, launched the first three of six envisaged distributed observation nodes, expanded its regional and international relevance, and has made great strides with an educational outreach programme. Three additional nodes are nearing completion and all should be operational by early 2008. The financial and institutional sustainability of SAEON was of paramount importance and consumed most of its energy during this establishment phase. The current three-year period (2006-2008) is devoted primarily to securing the scientific sustainability of the SAEON initiative through its nodes and associated partner networks, and to integrating its various functions

The relationship between butterfly richness and human population density in South Africa, at five spatial resolutions.

<p>Scatter plots of modelled median total butterfly richness (scaled and centred) and log human population density, at each of the five spatial resolutions, showing best fitting regression lines (mean ± standard error), for linear model 2 which was the best model in each case: a) 60 minutes, b) 30 minutes, c) 15 minutes, d) 5 minutes and e) 2 minutes.</p

Steps used for spatial distribution modelling and species richness determination, using Spatial Models 1.

<p>Species X reflects the focal species being modelled. The steps were carried out at five spatial resolutions. The steps were repeated using Spatial Model 2 (Step 4).</p><p>Steps used for spatial distribution modelling and species richness determination, using Spatial Models 1.</p

Modelled median total richness for South African butterflies at five grid square scales.

<p>Modelled median total richness (Spatial Model 1) for butterflies in South Africa at five grid square scales: a) 60 minutes, b) 30 minutes, c) 15 minutes, d) 5 minutes and e) 2 minutes. Higher richness is represented by darker shades of grey. In f), point localities of all butterfly distribution records (<i>n</i> = 326 530) in the atlas region (South Africa, Lesotho and Swaziland) which emanated from the SABCA project [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0124327#pone.0124327.ref030" target="_blank">30</a>] are shown.</p