Pierre Pistorius results 25
· Newest (Page 1/1, per page 25)
Author: Pierre Pistorius ×Clear All Filters
Search Results
Abundance of Indian Ocean humpback dolphins (Sousa plumbea) along the Garden Route of South AfricaOA Marine
Human development is placing growing pressure on coastal ecosystems worldwide. Coastal dolphins are consequently exposed to a range of anthropogenic threats, yet for many species, limited knowledge of population size and dynamics hinders effective conservation planning. Four species of humpback dolphin ( Sousa spp.) inhabit shallow coastal waters globally, and all are threatened by human activities. Along the South African coa...
Multi-colony tracking of a marine central place forager reveals a site specific yet broadly consistent foraging strategyNARA Subscribed
Colonial central place foraging seabirds with a wide species range inhabit highly heterogenous habitats, which may result in colony-specific foraging behaviours. Simultaneously tracking seabirds from multiple colonies is key to elucidating factors influencing foraging behaviour and determining how species might respond to environmental perturbations. Here, we investigate the foraging behaviour of gentoo penguins ( Pygoscelis p...
Marine megafauna species are affected by a wide range of anthropogenic threats. To evaluate the risk of such threats, species’ vulnerability to each threat must first be determined. We build on the existing threats classification scheme and ranking system of the International Union for Conservation of Nature (IUCN) Red List of Threatened Species by assessing the vulnerability of 256 marine megafauna species to 23 at‐sea threat...
Aim Competition is often proposed to drive niche segregation along multiple axes in speciose communities. Understanding spatial partitioning of foraging areas is particularly important in species that are constrained to a central place. We present a natural experiment examining variation in habitat preferences of congeneric Southern Ocean predators in sympatry and allopatry. Our aim was to ascertain consistency of habitat pref...
Small-scale movements and site fidelity of two sympatric sea turtle species at a remote atollNARA Subscribed
Understanding natural movement patterns and ecological roles of marine megafauna is a research priority best studied in areas with minimal human impact. The spatial distribution patterns specifically for immature turtles at foraging grounds have been highlighted as a research gap for effective management and conservation strategies for sea turtle populations. Capture–mark–recapture (CMR) records ( n = 2287) of 1672 immature gr...
Changes in marine ecosystems from human stressors, and concerns over how species will respond to these changes have emphasized the importance of understanding and monitoring crucial demographic parameters for population models. Long-lived, migratory, marine vertebrates such as sea turtles are particularly vulnerable to changes. Life-history parameters like growth-in-body size can be largely influenced by environmental processe...
Long-term changes in adult size of green turtles at Aldabra Atoll and implications for clutch size, sexual dimorphism and growth ratesNARA Subscribed
Around the world, declines in the mean size of nesting sea turtles have been reported with concerns of a concomitant decrease in the reproductive output of populations. Here, we explore this possibility using long-term observations of green turtles ( Chelonia mydas ) at Aldabra Atoll, Seychelles. Based on > 4500 individual measurements over 21 years (1996–2016), we found the curved carapace length of nesting females declined b...
Climate change impacts on seabirds and marine mammals: The importance of study duration, thermal tolerance and generation timeNARA Subscribed
Understanding climate change impacts on top predators is fundamental to marine biodiversity conservation, due to their increasingly threatened populations and their importance in marine ecosystems. We conducted a systematic review of the effects of climate change (prolonged, directional change) and climate variability on seabirds and marine mammals. We extracted data from 484 studies (4808 published studies were reviewed), com...
Many marine species exhibit fine‐scale population structure despite high mobility and a lack of physical barriers to dispersal, but the evolutionary drivers of differentiation in these systems are generally poorly understood. Here we investigate the potential role of habitat transitions and seasonal prey distributions on the evolution of population structure in the Indo‐Pacific bottlenose dolphin, Tursiops aduncus , off South...
Variation in cranial morphology of bottlenose dolphins (genus Tursiops ) off South AfricaNARA Subscribed
Taxonomy plays an important role in conservation biology. Despite the variety of methods used to differentiate units, some groups, such as Delphinidae within the Cetacea have proven difficult to untangle. This study aimed to shed light on morphological variation of the genus Tursiops in South African waters using geometric morphometrics and to distinguish morphological groups and variation in these groups. A total of 241 crani...
Sexual dimorphism in striped dolphin ( Stenella coeruleoalba ) crania from South AfricaNARA Subscribed
This study assessed the extent of sexual dimorphism in striped dolphin ( Stenella coeruleoalba ) cranial size and shape off the South African coast. Dorsal and ventral features of 60 striped dolphin crania from both the western and eastern coasts of South Africa were analyzed using landmark‐based geometric morphometrics. Although there was no evidence of dimorphism in cranial size, evidence for small, but significant, variatio...
Antarctic fur seal predation on cephalopods at Marion IslandNARA Subscribed
Pup mortality in southern elephant seals at Marion IslandNARA Subscribed
Previous1Next