Changes in Shellfish Species Composition and Mean Shell Size from a Late-Holocene Record of the West Coast of Southern Africa

1997 ◽  
Vol 24 (11) ◽  
pp. 1031-1044 ◽  
Author(s):  
Antonieta Jerardino
Keyword(s):  
Species Composition ◽  
Southern Africa ◽  
West Coast ◽  
Late Holocene ◽  
The West ◽  
Shell Size ◽  
Holocene Record

Taxonomy of the genus Ehrharta (Poaceae) in southern Africa: the Villosa group

Bothalia ◽  
1987 ◽  
Vol 17 (2) ◽  
pp. 191-194 ◽  
Author(s):  
G. E. Gibbs Russell
Keyword(s):  
Southern Africa ◽  
West Coast ◽  
Far East ◽  
Sandy Soils ◽  
Species Group ◽  
Southern Coast ◽  
Succulent Karoo ◽  
The West

The Villosa species group in the genus  Ehrharta Thunb. is differentiated morphologically by very large, profusely hairy, bearded and aristate spikelets and by a suffrutescent habit, with culms woody at the base and with reduced leaf blades. The Villosa group is composed of two species, one with a variety: E. thunbergii Gibbs Russell, nom. nov., E. villosa Schult. f. var.  villosa and E. villosa var. maxima Stapf. Members of the group occur on sandy soils in the Succulent Karoo and Fynbos Biomes, along the west coast in Strandveld and on the southern coast as far east as the Fish River. Morphologically, the group appears to be related to the Calycina and Capensis groups.

Spatiotemporal Variation in ΔR on the West Coast of North America in the Late Holocene: Implications for Dating the Shells of Marine Mollusks

2020 ◽  
Vol 85 (4) ◽  
pp. 676-693
Author(s):  
Ian Hutchinson
Keyword(s):  
North America ◽  
West Coast ◽  
Late Holocene ◽  
Southern Oscillation ◽  
Tidal Energy ◽  
Spatiotemporal Resolution ◽  
The West ◽  
Summer Maximum ◽  
High Alkalinity ◽  
High Degree

Radiocarbon ages on mollusk shells, which account for about half of the more than 8,000 dates from cultural deposits on the west coast of North America, need to be corrected for the local marine reservoir effect (ΔR) to yield true ages. Assays on “prebomb” shells show that ΔR increases poleward, echoing the age gradient in offshore waters. The meridional gradient in ΔR is not appreciably affected by the transition either from an upwelling regime to a downwelling regime north of 40°N–45°N or from a winter maximum-high alkalinity river discharge pattern to a summer maximum-low alkalinity pattern at the same latitude, probably because these changes are offset by increasing storminess and tidal energy in coastal areas. Mesoscale variations in ΔR along this gradient are attributable to contrasts in shore morphology and exposure. Data from 123 shell-wood pairs reveal similar patterns of temporal variation in ΔR in the late Holocene in the coastal ecoregions. The characteristic temporal pattern echoes phases of variable El Niño-Southern Oscillation (ENSO) activity. The high degree of variability in ΔR argues against the indiscriminate application of regionally uniform or trans-Holocene ΔR values and demands improvements in spatiotemporal resolution if shell is used to date cultural deposits.

Late-Holocene marine radiocarbon reservoir correction (ΔR) for the west coast of South Africa

The Holocene ◽  
2012 ◽  
Vol 22 (12) ◽  
pp. 1481-1489 ◽  
Author(s):  
Genevieve Dewar ◽  
Paula J Reimer ◽  
Judith Sealy ◽  
Stephan Woodborne
Keyword(s):  
South Africa ◽  
West Coast ◽  
Late Holocene ◽  
Sea Surface ◽  
Sea Surface Temperatures ◽  
Weighted Mean ◽  
The West ◽  
Proxy Data ◽  
Carbon Reservoir ◽  
Carbon Component

In order to calibrate radiocarbon ages based on samples with a marine carbon component it is important to know the marine carbon reservoir correction or ΔR value. This study measured the ΔR on both known-age pre-bomb marine shells and paired marine and terrestrial samples from two regions on the west coast of South Africa: the southwestern Cape and Namaqualand. Pooling the data by region produces ΔR values that are similar enough to use a west coast weighted mean ΔR of 146 ± 85 14C years to correctly calibrate marine shell or mixed marine and terrestrial 14C ages. There are however temporal differences in ΔR throughout the Holocene, which we compare with proxy data for upwelling and sea surface temperatures.

Diversity and habitat segregation of mangrove grapsoid crabs along the west coast of the Malay Peninsula

2020 ◽  
Vol 71 (8) ◽  
pp. 984
Author(s):  
Laura Ribero ◽  
Phaik Eem Lim ◽  
Rosli Ramli ◽  
Gianluca Polgar
Keyword(s):  
Species Composition ◽  
West Coast ◽  
Coastal Wetlands ◽  
Hot Spot ◽  
Malay Peninsula ◽  
The West ◽  
Ecological Traits ◽  
Management Actions ◽  
Different Types ◽  
Local Extinctions

South-East Asia is a biodiversity hot spot for several different animal and plant taxa, and grapsoid crabs are dominant components of its mangrove macrofauna. However, autecological traits of the species and assemblage structures are still largely undescribed. During the period 2012–14, we surveyed six mainland and insular mangrove sites along the west coast of the Malay Peninsula, four of which had not been investigated previously. Species composition differed among sites with different types of substrate and forest area. Small islands, characterised by coarser intertidal substrates, hosted remarkably different assemblages from mainland systems. Most of the species occurred in a small number of sites, suggesting stenotopic ecological traits or patchy distributions, and a marked variation in species composition and environmental conditions among sites was observed. This suggests that management actions assuming that this region’s coastal wetlands have comparable community compositions may likely lead to local extinctions of species, possibly affecting the regional biodiversity of these systems.

A taxonomic revision of the southern African native and naturalized species of Silene L. (Caryophyllaceae)

Bothalia ◽  
2012 ◽  
Vol 42 (2) ◽  
pp. 147-186
Author(s):  
J. C. Manning ◽  
P. Goldblatt
Keyword(s):  
New Species ◽  
Southern Africa ◽  
Morphological Variation ◽  
West Coast ◽  
Native Species ◽  
Taxonomic Revision ◽  
Western Cape ◽  
The West ◽  
Sem Micrographs ◽  
Two New Species

The native and naturalized species of Silene L. in southern Africa are reviewed, with full synonomy and the description of two new species from the West Coast of Western Cape. Eight native species and three naturalized species are recognized, including the first identification in southern Africa of the Mediterranean S. nocturna L. The identity of S. aethiopica Burm., which has remained unknown since its description, is established and is found to be the oldest name for S. clandestina Jacq. Patterns of morphological variation within each species are discussed and subspecies are recognized for geographically segregated groups of populations that are ± morphologically diagnosable. The following new names or combinations are made among the southern African taxa: S. aethiopica subsp. longiflora; S. burchellii subsp. modesta, subsp. multiflora, and subsp. pilosellifolia; S. crassifolia subsp. primuliflora; S. saldanhensis; S. rigens; and S. undulata subsp. polyantha. Each taxon is described, with information on ecology and distribution, and most species are illustrated, including SEM micrographs of the seeds.

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