David W. Johnston

ORCID: 0000-0003-2424-036X
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About
Contact & Profiles
Research Areas
  • Marine animal studies overview
  • Avian ecology and behavior
  • Arctic and Antarctic ice dynamics
  • Marine and fisheries research
  • Wildlife Ecology and Conservation
  • Underwater Acoustics Research
  • Species Distribution and Climate Change
  • Coral and Marine Ecosystems Studies
  • Turtle Biology and Conservation
  • Remote Sensing and LiDAR Applications
  • Plant and animal studies
  • Fish Ecology and Management Studies
  • Aerospace Engineering and Energy Systems
  • Animal Vocal Communication and Behavior
  • Cryospheric studies and observations
  • Botany, Ecology, and Taxonomy Studies
  • Rangeland and Wildlife Management
  • Marine and coastal plant biology
  • Isotope Analysis in Ecology
  • Cephalopods and Marine Biology
  • Animal Ecology and Behavior Studies
  • Ecology and Vegetation Dynamics Studies
  • Marine and coastal ecosystems
  • Fire effects on ecosystems
  • Wildlife-Road Interactions and Conservation

Duke University
2016-2025

University of South Carolina Beaufort
2013-2025

Marine Conservation Institute
2015-2024

Santa Cruz County Office of Education
2024

University of Hawaii System
2007-2023

University of Hawaiʻi at Mānoa
2023

UNSW Sydney
2018

University of Oxford
2018

Monash University
2018

The University of Melbourne
2018

ABSTRACT Since the last thorough review of effects anthropogenic noise on cetaceans in 1995, a substantial number research reports has been published and our ability to document response(s), or lack thereof, improved. While rigorous measurement responses remains important, there is an increased need interpret observed actions context population‐level consequences acceptable exposure levels. There little change sources noise, with notable addition from wind farms novel acoustic deterrent...

10.1111/j.1365-2907.2007.00104.x article EN Mammal Review 2007-04-01

Abstract Estimating animal populations is critical for wildlife management. Aerial surveys are used generating population estimates, but can be hampered by cost, logistical complexity, and human risk. Additionally, counts of organisms in aerial imagery tedious subjective. Automated approaches show promise, constrained long setup times difficulty discriminating animals aggregations. We combine unmanned aircraft systems (UAS), thermal computer vision to improve traditional survey methods....

10.1038/srep45127 article EN cc-by Scientific Reports 2017-03-24

Marine mammals can play important ecological roles in aquatic ecosystems, and their presence be key to community structure function. Consequently, marine are often considered indicators of ecosystem health flagship species. Yet, historical population declines caused by exploitation, additional current threats, such as climate change, fisheries bycatch, pollution maritime development, continue impact many mammal species, at least 25% classified threatened (Critically Endangered, Endangered or...

10.3354/esr01115 article EN cc-by Endangered Species Research 2021-01-28

Ecological relationships of krill and whales have not been explored in the Western Antarctic Peninsula (WAP), only rarely studied elsewhere Southern Ocean. In austral autumn we observed an extremely high density (5.1 per km2) humpback (Megaptera novaeangliae) feeding on a super-aggregation (Euphausia superba) Wilhelmina Bay. The biomass was approximately 2 million tons, distributed over area 100 km2 at densities up to 2000 individuals m−3; reports such 'super-aggregations' absent scientific...

10.1371/journal.pone.0019173 article EN cc-by PLoS ONE 2011-04-27

It's the prey that matters Although many people think of dinosaurs as being largest creatures to have lived on Earth, true known animal is still here today—the blue whale. How whales were able become so large has long been interest. Goldbogen et al. used field-collected data feeding and diving events across different types calculate rates energy gain (see Perspective by Williams). They found increased body size facilitates capture. Furthermore, body-size increase in marine environment...

10.1126/science.aax9044 article EN Science 2019-12-13

Abstract Marine megafauna are difficult to observe and count because many species travel widely spend large amounts of time submerged. As such, management programmes seeking conserve these often hampered by limited information about population levels. Unoccupied aircraft systems (UAS, aka drones) provide a potentially useful technique for assessing marine animal populations, but central challenge lies in analysing the vast data generated images or video acquired during each flight. Neural...

10.1111/2041-210x.13132 article EN publisher-specific-oa Methods in Ecology and Evolution 2018-12-14

The use of drones to study marine animals shows promise for the examination numerous aspects their ecology, behaviour, health and movement patterns. However, responses some phyla presence varies broadly, as do general operational protocols used them. Inconsistent methodological approaches could lead difficulties comparing studies can call into question repeatability research. This review draws on current literature researchers with a wealth practical experience outline idiosyncrasies...

10.3390/drones4040064 article EN cc-by Drones 2020-09-25

Very high-resolution satellite imagery (≤5 m resolution) has become available on a spatial and temporal scale appropriate for dynamic wetland management conservation across large areas. Estuarine wetlands have the potential to be mapped at detailed habitat with frequency that allows immediate monitoring after storms, in response human disturbances, face of sea-level rise. Yet mapping requires significant fieldwork run modern classification algorithms estuarine environments can difficult...

10.3390/rs10081257 article EN cc-by Remote Sensing 2018-08-10

Abstract The flourishing application of drones within marine science provides more opportunity to conduct photogrammetric studies on large and varied populations many different species. While these new platforms are increasing the size availability imagery datasets, established photogrammetry methods require considerable manual input, allowing individual bias in techniques influence measurements, error magnifying time required apply techniques. Here, we introduce next generation utilizing a...

10.1111/2041-210x.13246 article EN publisher-specific-oa Methods in Ecology and Evolution 2019-06-28

Antarctic humpback whales are recovering from near extirpation commercial whaling. To understand the dynamics of this recovery and establish a baseline to monitor impacts rapidly changing environment, we investigated sex ratios pregnancy rates females within Western Peninsula (WAP) feeding population. DNA profiling 577 tissue samples (2010–2016) identified 239 males 268 females. Blubber progesterone levels indicated 63.5% biopsied were pregnant. This proportion varied significantly across...

10.1098/rsos.180017 article EN cc-by Royal Society Open Science 2018-05-01

The krill surplus hypothesis of unlimited prey resources available for Antarctic predators due to commercial whaling in the 20th century has remained largely untested since 1970s. Rapid warming Western Peninsula (WAP) over past 50 years resulted decreased seasonal ice cover and a reduction krill. latter is being exacerbated by fishery region. Despite this, humpback whale populations have increased but may be at threshold growth based on these human-induced changes. Understanding how...

10.1111/gcb.16559 article EN cc-by Global Change Biology 2023-01-15
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