Comparisons of life-history traits of the alien invasive Semimytilus algosus and three other mytilid mussels on the West Coast of South Africa

2018 ◽  
Vol 607 ◽  
pp. 113-127 ◽  
Author(s):  
Z Zeeman ◽  
GM Branch ◽  
D Pillay
Keyword(s):  
South Africa ◽  
Life History ◽  
West Coast ◽  
Life History Traits ◽  
The West ◽  
Semimytilus Algosus

scholarly journals Spatio-temporal patterns in maturation of the chokka squid (Loligo vulgaris reynaudii) off the coast of South Africa

2006 ◽  
Vol 63 (9) ◽  
pp. 1649-1664 ◽  
Author(s):  
L.J.H. Olyott ◽  
W.H.H. Sauer ◽  
A.J. Booth
Keyword(s):  
South Africa ◽  
Life History ◽  
West Coast ◽  
Sex Ratios ◽  
Conclusive Evidence ◽  
The West ◽  
Loligo Vulgaris ◽  
Spawning Areas ◽  
Spatio Temporal ◽  
Temporal And Spatial Characteristics

Abstract Knowledge of the temporal and spatial characteristics of chokka squid (Loligo vulgaris reynaudii) biology in South African waters is limited, so the possibility of there being a geographically fragmented stock was examined by investigating the distribution of maturity patterns for the species, covering all known spawning areas and using both historical and recent data. Gonadosomatic indices (GSI) varied between year-round consistency and apparent seasonal peaks in both summer and winter; there was no clear spatial pattern. Monthly percentage maturity provided further evidence for two peak reproductive periods each year, although mature squid were present throughout. Sex ratios demonstrated great variability between different areas and life history stages. Male-biased sex ratios were only apparent on the inshore spawning grounds and ranged between 1.118:1 and 4.267:1. Size at sexual maturity was also seasonal, squid maturing smaller in winter/spring than in summer/autumn. Also, squid in the east matured smaller than squid in the west. Although the results from the present study do not provide conclusive evidence of distinct geographic populations, squid likely spawn over a significantly larger area of the Agulhas Bank than previously estimated, and squid on the west coast of South Africa may return to spawn on the western portion of the Agulhas Bank. It remains likely, however, that the east and west coast populations are a single stock and that migration of juveniles to the west coast and their subsequent return as sub-adults is an integral but non-essential and variable part of the life history.

Seasonal occurrence and diel calling behaviour of Antarctic blue whales and fin whales in relation to environmental conditions off the west coast of South Africa

2019 ◽  
Vol 190 ◽  
pp. 25-39 ◽  
Author(s):  
Fannie W. Shabangu ◽  
Ken P. Findlay ◽  
Dawit Yemane ◽  
Kathleen M. Stafford ◽  
Marcel van den Berg ◽  
...  
Keyword(s):  
South Africa ◽  
Environmental Conditions ◽  
West Coast ◽  
Seasonal Occurrence ◽  
The West ◽  
Calling Behaviour ◽  
Fin Whales ◽  
Blue Whales

scholarly journals Shark–Cetacean trophic interaction, Duinefontein, Koeberg, (5 Ma), South Africa

2015 ◽  
Vol Volume 111 (Number 11/12) ◽  
Author(s):  
Romala Govender ◽  
Keyword(s):  
South Africa ◽  
Cause Of Death ◽  
West Coast ◽  
Trophic Interaction ◽  
The West ◽  
Carcharodon Carcharias ◽  
Inverted Position ◽  
Bite Marks ◽  
Shark Teeth ◽  
Long Time

Abstract This study forms part of a larger project to reconstruct the Mio-Pliocene marine palaeoenvironment along South Africa’s west coast. It documents the shark–cetacean trophic interaction during the Zanclean (5 Ma) at Duinefontein (Koeberg). The damage described on the fragmentary cetacean bones was compared with similar damage observed on fossils from Langebaanweg, a Mio-Pliocene site on the west coast of South Africa, and data present in the literature. This comparison showed that the damage was the result of shark bites. The state of preservation makes it difficult to determine if the shark bite marks were the cause of death or as a result of scavenging. The presence of the bite marks on the bone would, however, indicate some degree of skeletonisation. Bite marks on some cranial fragments would suggest that the cetacean’s body was in an inverted position typical of a floating carcass. The preservation of the material suggests that the bones were exposed to wave action resulting in their fragmentation as well as abrasion, polishing and rolling. It also suggests that the cetacean skeletons were exposed for a long time prior to burial. The morphology of the bites suggests that the damage was inflicted by sharks with serrated and unserrated teeth. Shark teeth collected from the deposit include megalodon (Carcharodon megalodon), white (Carcharodon carcharias) as well as mako (Isurus sp. and Cosmopolitodus hastalis) sharks, making these sharks the most likely predators/scavengers.

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