scholarly journals Estimates of abundance and change in abundance of the Indo-Pacific bottlenose dolphins (Tursiops aduncus) along the south coast of South Africa

2019 ◽  
Author(s):  
OA Vargas-Fonseca ◽  
SP Kirkman ◽  
WC Oosthuizen ◽  
T Bouveroux ◽  
V Cockcroft ◽  
...  
Keyword(s):  
South Africa ◽  
Conservation Status ◽  
Bottlenose Dolphins ◽  
South Coast ◽  
The South ◽  
Model Estimate ◽  
Entire Study ◽  
Tursiops Aduncus ◽  
Photo Identification ◽  
Open Population

AbstractWe investigated the abundance of Indo-Pacific bottlenose dolphins (Tursiops aduncus) along the south coast of South Africa, from the Goukamma Marine Protected Area (MPA) to the Tsitsikamma MPA, between 2014 and 2016. During this period, 662.3h of boat-based photo-identification survey effort was carried out, and the sighting histories of 817 identified individuals were used to estimate abundance using mark-recapture modelling. The selected open population model (POPAN) provided an estimate of 2,295 individuals (95% CI: 1,157-4,553) for the entire study area. A model estimate was produced for a subset of the study area, Plettenberg Bay, which could be compared with a past estimate for this location (2002-2003). The comparison suggested a 72.3% decrease in abundance, from 6,997 (95% CI: 5,230-9,492) in 2002-2003 to 1,940 (95% CI: 1,448-2,600) in 2014-2016. The decline in abundance was supported by a 72% reduction in mean group size for Plettenberg Bay between the periods. It is essential to be able to assess abundance changes at other locations to inform revision of T. aduncus conservation status in South Africa.

Distribution and habitat use of Indo-Pacific bottlenose dolphins Tursiops aduncus along the south coast of South Africa

2018 ◽  
Vol 40 (4) ◽  
pp. 439-450 ◽  
Author(s):  
OA Vargas-Fonseca ◽  
SP Kirkman ◽  
D Conry ◽  
GM Rishworth ◽  
V Cockcroft ◽  
...  
Keyword(s):  
South Africa ◽  
Habitat Use ◽  
Bottlenose Dolphins ◽  
South Coast ◽  
The South ◽  
Tursiops Aduncus

scholarly journals Abundance of Indo-Pacific bottlenose dolphins (Tursiops aduncus) along the south coast of South Africa

PLoS ONE ◽  
2020 ◽  
Vol 15 (10) ◽  
pp. e0227085
Author(s):  
O. Alejandra Vargas-Fonseca ◽  
Stephen P. Kirkman ◽  
W. Chris Oosthuizen ◽  
Thibaut Bouveroux ◽  
Vic Cockcroft ◽  
...  
Keyword(s):  
South Africa ◽  
Bottlenose Dolphins ◽  
South Coast ◽  
The South ◽  
Tursiops Aduncus

scholarly journals Social Structure, Habitat Use and Injuries of Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) Reveal Isolated, Coastal, and Threatened Communities in the South Pacific

2021 ◽  
Vol 8 ◽  
Author(s):  
Claire Daisy Bonneville ◽  
Solène Derville ◽  
Jolanda A. Luksenburg ◽  
Marc Oremus ◽  
Claire Garrigue
Keyword(s):  
Habitat Use ◽  
Social Structure ◽  
New Caledonia ◽  
Conservation Status ◽  
Bottlenose Dolphins ◽  
South Pacific ◽  
The South ◽  
Cetacean Species ◽  
Tursiops Aduncus ◽  
South West

Understanding population structure and habitat use of poorly known cetacean species is a first step toward scientifically informed management decisions. In the southern range of New Caledonia (South Pacific), a long-term dataset of Indo-Pacific bottlenose dolphins (Tursiops aduncus) encounters primarily during winter seasons 1997 to 2019 (473 group observations) was used to assess social structure, habitat use and potential threats. A total of 338 individuals were photographically identified, forming three distinct communities in the south-west lagoon, the south lagoon and the Isle of Pines. Mark-recapture histories revealed that the three communities were weakly connected and might be considered as independent management units. Suitable habitats were estimated with presence-only distribution models relative to topographic and seabed substrate predictors. Habitat suitability increased with proximity to coasts or reefs, at shallow depth, and over muddy bottom. These habitats had various levels of protection and were used by humans, mostly in the south-west lagoon. External injuries were interpreted to determine natural interactions and potential anthropogenic threats. The prevalence in injuries did not vary among the three areas. A substantial proportion of injuries related to propeller hits was reported, representing a total of 16.7% (34 of 204) of all injuries observed on dolphins. The three communities of Indo-Pacific bottlenose dolphins revealed in the southern part of New Caledonia are particularly vulnerable due to their insularity, their coastal habitat use and the low levels of connectivity found among them. In a context of increasing maritime traffic, fishing and recreational activities, this study provides a useful baseline to the urgent assessment of the conservation status of dolphins in New Caledonia.

scholarly journals Southern Hemisphere anticyclonic circulation drives oceanic and climatic conditions in late Holocene southernmost Africa

2017 ◽  
Vol 13 (6) ◽  
pp. 649-665 ◽  
Author(s):  
Annette Hahn ◽  
Enno Schefuß ◽  
Sergio Andò ◽  
Hayley C. Cawthra ◽  
Peter Frenzel ◽  
...  
Keyword(s):  
South Africa ◽  
Climatic Conditions ◽  
Sea Surface ◽  
South Coast ◽  
Ice Age ◽  
Sea Surface Temperatures ◽  
The South ◽  
Anticyclonic Circulation ◽  
Surface Temperatures ◽  
Precipitation Regimes

Abstract. Due to the high sensitivity of southern Africa to climate change, a reliable understanding of its hydrological system is crucial. Recent studies of the regional climatic system have revealed a highly complex interplay of forcing factors on precipitation regimes. This includes the influence of the tropical easterlies, the strength of the southern hemispheric westerlies as well as sea surface temperatures along the coast of the subcontinent. However, very few marine records have been available in order to study the coupling of marine and atmospheric circulation systems. Here we present results from a marine sediment core, recovered in shallow waters off the Gouritz River mouth on the south coast of South Africa. Core GeoB18308-1 allows a closer view of the last  ∼  4 kyr. Climate sensitive organic proxies, like the distribution and isotopic composition of plant-wax lipids as well as indicators for sea surface temperatures and soil input, give information on oceanographic and hydrologic changes during the recorded time period. Moreover, the micropaleontology, mineralogical and elemental composition of the sediments reflect the variability of the terrigenous input to the core site. The combination of down-core sediment signatures and a catchment-wide provenance study indicate that the Little Ice Age ( ∼  300–650 cal yr BP) was characterized by climatic conditions favorable to torrential flood events. The Medieval Climate Anomaly ( ∼  950–650 cal yr BP) is expressed by lower sea surface temperatures in the Mossel Bay area and humid conditions in the Gouritz River catchment. These new results suggest that the coincidence of humid conditions and cooler sea surface temperatures along the south coast of South Africa resulted from a strengthened and more southerly anticyclonic circulation. Most probably, the transport of moisture from the Indian Ocean by strong subtropical easterlies was coupled with Agulhas Bank upwelling pulses, which were initiated by an increase in Agulhas Current strength.

Occurrence of Indo‐Pacific bottlenose dolphins ( Tursiops aduncus ) off the Wild Coast of South Africa using photographic identification

2020 ◽  
Vol 37 (1) ◽  
pp. 220-234
Author(s):  
Michelle Caputo ◽  
Thibaut Bouveroux ◽  
Pierre William Froneman ◽  
Titus Shaanika ◽  
Stephanie Plön
Keyword(s):  
South Africa ◽  
Bottlenose Dolphins ◽  
Tursiops Aduncus
Sign in / Sign up

Export Citation Format

Share Document