49 research outputs found
Using Unoccupied Aerial Vehicles to estimate availability and group size error for aerial surveys of coastal dolphins
Aerial surveys are frequently used to estimate the abundance of marine mammals, but their accuracy is dependent upon obtaining a measure of the availability of animals to visual detection. Existing methods for characterizing availability have limitations and do not necessarily reflect true availability. Here, we present a method of using small, vessel-launched, multi-rotor Unoccupied Aerial Vehicles (UAVs, or drones) to collect video of dolphins to characterize availability and investigate error surrounding group size estimates. We collected over 20 h of aerial video of dive-surfacing behaviour across 32 encounters with Australian humpback dolphins Sousa sahulensis off north-western Australia. Mean surfacing and dive periods were 7.85 sec (se = 0.26) and 39.27 sec (se = 1.31) respectively. Dolphin encounters were split into 56 focal follows of consistent group composition to which example approaches to estimating availability were applied. Non-instantaneous availability estimates, assuming a 7 sec observation window, ranged between 0.22 and 0.88, with a mean availability of 0.46 (CV = 0.34). Availability tended to increase with increasing group size. We found a downward bias in group size estimation, with true group size typically one individual more than would have been estimated by a human observer during a standard aerial survey. The variability of availability estimates between focal follows highlights the importance of sampling across a variety of group sizes, compositions and environmental conditions. Through data re-sampling exercises, we explored the influence of sample size on availability estimates and their precision, with results providing an indication of target sample sizes to minimize bias in future research. We show that UAVs can provide an effective and relatively inexpensive method of characterizing dolphin availability with several advantages over existing approaches. The example estimates obtained for humpback dolphins are within the range of values obtained for other shallow-water, small cetaceans, and will directly inform a government-run program of aerial surveys in the region
Assessing the viability of estimating baleen whale abundance from tourist vessels
Many populations of southern hemisphere baleen whales are recovering and are again becoming dominant consumers in the Southern Ocean. Key to understanding the present and future role of baleen whales in Southern Ocean ecosystems is determining their abundance on foraging grounds. Distance sampling is the standard method for estimating baleen whale abundance but requires specific logistic requirements which are rarely achieved in the remote Southern Ocean. We explore the potential use of tourist vessel-based sampling as a cost-effective solution for conducting distance sampling surveys for baleen whales in the Southern Ocean. We used a dataset of tourist vessel locations from the southwest Atlantic sector of the Southern Ocean and published knowledge from Southern Ocean sighting surveys to determine the number of tourist vessel voyages required for robust abundance estimates. Second, we simulated the abundance and distributions of four baleen whale species for the study area and sampled them with both standardized line transect surveys and non-standardized tourist vessel-based surveys, then compared modeled abundance and distributions from each survey to the original simulation. For the southwest Atlantic, we show that 12-22 tourist vessel voyages are likely required to estimate abundance for humpback and fin whales, with relative estimates for blue, sei, Antarctic minke, and southern right whales. Second, we show tourist vessel-based surveys outperformed standardized line transect surveys at reproducing simulated baleen whale abundances and distribution. These analyses suggest tourist vessel-based surveys are a viable method for estimating baleen whale abundance in remote regions. For the southwest Atlantic, the relatively cost-effective nature of tourist vessel-based survey and regularity of tourist vessel voyages could allow for annual and intra-annual estimates of abundance, a fundamental improvement on current methods, which may capture spatiotemporal trends in baleen whale movements on forging grounds. Comparative modeling of sampling methods provided insights into the behavior of general additive model-based abundance modeling, contributing to the development of detailed guidelines of best practices for these approaches. Through successful engagement with tourist company partners, this method has the potential to characterize abundance across a variety of marine species and spaces globally, and deliver high-quality scientific outcomes relevant to management organizations.publishedVersio
A Best Practice Guide for Community Based Participatory Research (CBPR) in Transgender and Nonbinary (TNB) Health
This guide describes best practices for community-based participatory research (CBPR) with transgender and nonbinary (TNB) communities. We hope it will be a resource for people involved or interested in TNB health research and will make CBPR approachable, actionable and compelling. We anticipate readers of this guide will hold varying identities, experiences, and expertise, including their understanding of or familiarity with research and TNB communities. It is important to explicitly recognize that there are TNB people of varying cultural/language backgrounds already doing this work and to avoid reinforcing assumptions that researchers are not TNB, Black, Indigenous, people of color (BIPOC), or TNB BIPOC. While we believe the best people to initiate and practice TNB health CBPR are TNB people, we also recognize that the majority of people involved in TNB health research are not TNB themselves. This guide is designed to offer insight to all audiences. Our goal is to provide an overview of themes we believe are important and best practices to collaboratively develop and carry-out research with TNB communities
Guía de mejores prácticas para la investigación participativa basada en la comunidad (Community-Based Participatory Research - CBPR) sobre la salud de personas transgénero y no binarias (Transgender and Nonbinary - TNB)
Esta guía describe las mejores prácticas para la investigación participativa basada en la comunidad (CBPR, por sus siglas en inglés) con comunidades transgénero y no binarias (TNB, por sus siglas en inglés). Esperamos que sea un recurso para las personas involucradas o interesadas en la investigación de la salud en la comunidad TNB y que haga que la CBPR sea accesible, factible y convincente. Anticipamos que les lectores de esta guía tendrán diferentes identidades, experiencias y conocimientos, además de comprender y estar familiarizades con las investigaciones y las comunidades TNB. Es importante reconocer explícitamente que hay personas TNB de diversos orígenes culturales/lingüísticos que ya están haciendo este trabajo y evitar reforzar suposiciones de que les investigadores no son TNB, negres, indígenas, personas racializadas (BIPOC, por sus siglas en inglés), o BICOP TNB. Aunque creemos que las mejores personas para iniciar y llevar a cabo la CBPR sobre la salud en la comunidad TNB son las personas TNB, también reconocemos que la mayoría de las personas involucradas en la investigación sobre salud en la comunidad TNB no son ellas mismas TNB. Esta guía está diseñada para ofrecer una comprensión a todo el público. Nuestra meta es proporcionar una visión general de los temas que consideramos importantes y las mejores prácticas para desarrollar y llevar a cabo la investigación en colaboración con las comunidades TN
Induction chemotherapy followed by chemoradiotherapy versus chemoradiotherapy alone as neoadjuvant treatment for locally recurrent rectal cancer: study protocol of a multicentre, open-label, parallel-arms, randomized controlled study (PelvEx II)
Background A resection with clear margins (R0 resection) is the most important prognostic factor in patients with locally recurrent rectal cancer (LRRC). However, this is achieved in only 60 per cent of patients. The aim of this study is to investigate whether the addition of induction chemotherapy to neoadjuvant chemo(re)irradiation improves the R0 resection rate in LRRC. Methods This multicentre, international, open-label, phase III, parallel-arms study will enrol 364 patients with resectable LRRC after previous partial or total mesorectal resection without synchronous distant metastases or recent chemo- and/or radiotherapy treatment. Patients will be randomized to receive either induction chemotherapy (three 3-week cycles of CAPOX (capecitabine, oxaliplatin), four 2-week cycles of FOLFOX (5-fluorouracil, leucovorin, oxaliplatin) or FOLFORI (5-fluorouracil, leucovorin, irinotecan)) followed by neoadjuvant chemoradiotherapy and surgery (experimental arm) or neoadjuvant chemoradiotherapy and surgery alone (control arm). Tumours will be restaged using MRI and, in the experimental arm, a further cycle of CAPOX or two cycles of FOLFOX/FOLFIRI will be administered before chemoradiotherapy in case of stable or responsive disease. The radiotherapy dose will be 25 × 2.0 Gy or 28 × 1.8 Gy in radiotherapy-naive patients, and 15 × 2.0 Gy in previously irradiated patients. The concomitant chemotherapy agent will be capecitabine administered twice daily at a dose of 825 mg/m2 on radiotherapy days. The primary endpoint of the study is the R0 resection rate. Secondary endpoints are long-term oncological outcomes, radiological and pathological response, toxicity, postoperative complications, costs, and quality of life. Discussion This trial protocol describes the PelvEx II study. PelvEx II, designed as a multicentre, open-label, phase III, parallel-arms study, is the first randomized study to compare induction chemotherapy followed by neoadjuvant chemo(re)irradiation and surgery with neoadjuvant chemo(re)irradiation and surgery alone in patients with locally recurrent rectal cancer, with the aim of improving the number of R0 resections
Drone images afford more detections of marine wildlife than real-time observers during simultaneous large-scale surveys
There are many advantages to transitioning from conducting marine wildlife surveys via human observers onboard light-aircraft, to capturing aerial imagery using drones. However, it is important to maintain the validity of long-term data series whilst transitioning from observer to imagery surveys. We need to understand how the detection rates of target species in images compare to those collected from observers in piloted aircraft, and the factors influencing detection rates from each platform. We conducted trial ScanEagle drone surveys of dugongs in Shark Bay, Western Australia, covering the full extent of the drone’s range (∼100 km), concurrently with observer surveys, with the drone flying above or just behind the piloted aircraft. We aimed to test the assumption that drone imagery could provide comparable detection rates of dugongs to human observers when influenced by same environmental conditions. Overall, the dugong sighting rate (i.e., count of individual dugongs) was 1.3 (95% CI [0.98–1.84]) times higher from the drone images than from the observers. The group sighting rate was similar for the two platforms, however the group sizes detected within the drone images were significantly larger than those recorded by the observers, which explained the overall difference in sighting rates. Cloud cover appeared to be the only covariate affecting the two platforms differently; the incidence of cloud cover resulted in smaller group sizes being detected by both platforms, but the observer group sizes dropped much more dramatically (by 71% (95% CI [31–88]) compared to no cloud) than the group sizes detected in the drone images (14% (95% CI [−28–57])). Water visibility and the Beaufort sea state also affected dugong counts and group sizes, but in the same way for both platforms. This is the first direct simultaneous comparison between sightings from observers in piloted aircraft and a drone and demonstrates the potential for drone surveys over a large spatial-scale
Deep learning algorithm outperforms experienced human observer at detection of blue whale D‐calls: a double‐observer analysis
Abstract An automated algorithm for passive acoustic detection of blue whale D‐calls was developed based on established deep learning methods for image recognition via the DenseNet architecture. The detector was trained on annotated acoustic recordings from the Antarctic, and performance of the detector was assessed by calculating precision and recall using a separate independent dataset also from the Antarctic. Detections from both the human analyst and automated detector were then inspected by an independent judge to identify any calls missed by either approach and to adjudicate whether the apparent false‐positive detections from the automated approach were actually true positives. A final performance assessment was conducted using double‐observer methods (via a closed‐population Huggins mark–recapture model) to assess the probability of detection of calls by both the human analyst and automated detector, based on the assumption of false‐positive‐free adjudicated detections. According to our double‐observer analysis, the automated detector showed superior performance with higher recall and fewer false positives than the original human analyst, and with performance similar to existing top automated detectors. To understand the performance of both detectors we inspected the time‐series and signal‐to‐noise ratio (SNR) of detections for the test dataset, and found that most of the advantages from the automated detector occurred at low and medium SNR
The recovery of Antarctica’s giants – baleen whales
- Baleen whales are predominately summer visitors to Antarctic waters, where they feed on large swarms of zooplankton, primarily Antarctic Krill (Euphausia superba).
- Over 2 million whales were killed in Southern Hemisphere whaling operations in the 20th Century 1.
- Many species were brought to the edge of extinction as a result of this commercial exploitation 2,3.
- The IUCN categorise the main Antarctic baleen whale species: (i) Antarctic blue whales (Balaenoptera musculus intermedia) as Critically Endangered; (ii) fin whales ( physalus) as Vulnerable; (iii) humpback whales (Megaptera novaeangliae) as Least Concern; (iv) southern right whales (Eubalaena australis) as Least Concern, although the sub-population in Chile and Peru is Critically Endangered; (v); sei whales (B. borealis) as Endangered; (vi) Antarctic minke whales (B. bonaerensis) as Near Threatened; (vii) common minke whales (B. acutorostrata) as Unknown; and (viii) pygmy blue whales (B. musculus brevicauda) as Data Deficient.
- Many Antarctic baleen whale populations are showing signs of recovery 4-6, but ongoing monitoring is essential so trends can be closely tracked because they face threats from climate change and direct anthropogenic impacts