Long-term Monitoring Projects Research Articles

Long-term monitoring of a flagship bird species in agroecosystems enhances stakeholder engagement in biodiversity conservation

Conservation efforts are needed in the face of the rapid decline in farmland birds over the past decades. While existing conservation strategies have shown limited success, there is a growing recognition of the role of farmers as primary stakeholders in agroecosystems conservation. We applied the "Human Dimension" approach, which emphasizes the importance of human perspectives on wildlife conservation, to assess whether a long-term monitoring project of barn swallows Hirundo rustica, ongoing since 1999, has heightened farmers’ awareness regarding biodiversity protection. Indeed, while monitoring serves to track population trends and understand the factors influencing species dynamics, it also provides opportunities for interaction between researchers and farmers. Through in-person administration of the questionnaire, we investigated the impact of the barn swallow monitoring project on farmers’ environmental consciousness in terms of their perceptions of the environment, knowledge about priority habitats for biodiversity, and preferences for environmental awareness strategies. Subsequently, we investigated whether environmental consciousness and the participation in the barn swallow monitoring project translated into their inclination to implement costless actions for barn swallow conservation. Our findings suggest that the barn swallow monitoring project may not have enhanced farmers’ environmental consciousness. However, a higher environmental consciousness and the engagement in the barn swallow monitoring project were associated to a greater willingness to undertake actions in support of barn swallows. This study highlights the potential of long-term projects in fostering the conservation of charismatic species through establishing a mutual trust between farmers and researchers over years of monitoring, with cascading benefits for the barn swallows.

Connecting separate monitoring programs through the SoundCoop

Passive acoustic monitoring (PAM) data collection has been growing exponentially, resulting in petabytes of data that document ocean soundscapes, how they change over time, and what animals use these ecosystems at varying timescales. Efficiently extracting this critical information and comparing it to other datasets in the context of ecosystem-based management is a Big Data challenge that traditional desktop processing methods cannot address. The curation, management, and dissemination of PAM datasets is another challenge in need of collaborative progress. To meet these exigencies, a multi-agency funded Sound Cooperative (SoundCoop) project is building community-focused, national cyberinfrastructure capability for PAM data to promote improved, scalable and sustainable accessibility and applications for management and science. Driven by partnerships and framed by four case studies, the SoundCoop has established guidance on the standardized processing of sound level metrics using free software toolkits and begun developing core cyberinfrastructure components that future PAM projects can leverage. U.S. and international scientists contributed PAM data collected across 10 long-term monitoring projects to operationalize the production of hybrid-millidecade spectra across a diversity of labs/instruments. Collectively, the contributed data demonstrate the value of standardized processing that enables the creation of comparable results from disparate monitoring efforts.

There and Back Again—The Igatu Hotspot Siliciclastic Caves: Expanding the Data for Subterranean Fauna in Brazil, Chapada Diamantina Region

The caves of Igatu, municipality of Andaraí, belonging to the region known as Chapada Diamantina represent a new hotspot of subterranean fauna. These caves are siliciclastic, which are sedimentary rocks where silica predominates, such as sandstones and (following metamorphism) quartzites, which makes them even more relevant from the point of view of subterranean diversity. For five caves, which we named Igatu Cave System (ICS), thirty-seven obligate cave species were found, of which thirty-five were troglobitic and two were stygobitic. The troglobitic taxa for ICS belong to three phyla, nine classes, 18 orders, and 32 families, representing a high phylogenetic diversity. Some taxa were, for the first time, reported as troglobitic in Brazil and even worldwide, such as Acari and scutigeromorphans (Chilopoda). We started the studies in 2009 and continue trough long-term monitoring projects. Some threats, severe in the past, such as “garimpo’’ (illegal small-scale artisanal mining) continue nowadays in an incipient way; however, the urban expansion due to the touristic appeal is also considered a threat. Our data ranked ICS as the Brazilian hotspot with the highest number of troglobitic/stygobitic species.

Towards a standardised set of data analyses for long-term genetic monitoring of grouse using non-invasive sampling: a case study on western capercaillie

Genetic monitoring has become a popular instrument in the conservation of endangered species, allowing to estimate size and genetic structure of wild populations. Long-term monitoring projects are essential to recognize demographic changes and impact of human activities. Since 2011, an extensive monitoring project on the population size and trends, as well as spatial distribution and survival rates, of two grouse species including the western capercaillie, Tetrao urogallus, has been conducted in Tyrol, in the eastern part of the European Alps, where T. urogallus males are huntable under specific regulations. In this case study, we aimed to compile a set of analyses to be employed in evaluating data from dropping and feather samples for conservation studies. Using eleven microsatellite and two sex markers, we genotyped 251 faeces and feathers of T. urogallus collected in East Tyrol in spring 2019. We analysed population structure and mobility patterns, including sex differences in genetic diversity and mobility. The relationship between habitat parameters and genetic diversity was investigated using multiple linear regressions. We showed that the investigated T. urogallus population is well mixed and likely well connected to neighbouring populations. We also found sex-specific mobility patterns that support female-biased dispersal. As the last step, we demonstrated the general feasibility of a modelling approach using habitat parameters. With this pilot study, further analysis of data is possible for the whole monitoring project, giving a better insight in the grouse populations in Tyrol.

Long-term trends from Citizen Scientists: 24 years of breeding success data of African Oystercatchers Haematopus moquini in the Garden Route

Long-term data on breeding success in beach-nesting birds in southern Africa are scarce. Citizen science projects have risen to the forefront of large dataset collection efforts globally, with several local projects helping us unpack long-term trends for species in southern Africa. A long-term monitoring project on African Oystercatcher Haematopus moquini breeding success in parts of the Garden Route on the south coast, conducted by the Lakes Bird Club, enables us to determine whether conservation efforts are positively influencing the species there. Since the onset of the study in 1997/1998, there has been a steady increase in the number of breeding pairs at Knysna and Sedgefield, but not at Brenton-on-Sea. A similar increase in hatching success is recorded, with an overall increase in the number of fledglings per adult pair over the area throughout the study. Collectively, this indicates that some local and national conservation efforts, such as the beach driving ban and awareness campaigns like #ShareTheShores, have been successful, leading to positive trends in these parameters for this species. This article highlights the usefulness of long-term datasets for corroborating outcomes from other large datasets, like the Southern African Bird Atlas Project 2.

Using Coral Color to Indicate Coral Health in Five Caribbean Species

Coral reefs are one of the most biodiverse and productive ecosystems on Earth, and color has been shown to indicate coral health in Australian and Hawaiian reef systems. However, no standardized method exists to quantify coral health for Caribbean corals. Therefore, a health assessment card using coral color was developed for five species of Caribbean corals to monitor coral health non-invasively. To quantify coral health, individual corals of each species were photographed in a controlled environment to develop color profiles. Simultaneously, nondestructive measurements of “health” were quantified by measuring photosynthetic efficiency (Fv/Fm) using pulse amplitude modulation (PAM) fluorometry, which determines how efficiently the symbiotic algae provides energy to the coral host. The results of this work successfully corresponded photosynthetic efficiency to coral color for five dominant species of Caribbean corals to develop a Coral Health Assessment Card for Caribbean reefs. Implementing a standardized assessment of symbiont performance can assist in monitoring changes in coral health, which can consequently be implemented into long-term and widespread monitoring projects to track overall Caribbean reef health. KEYWORDS: Photosynthetic Efficiency, Symbiodinium spp., Coral Bleaching, Pulse-amplitude Modulated Fluorometry, Health Assessment

An acoustic detection dataset of birds (Aves) in montane forests using a deep learning approach.

Long-term monitoring is needed to understand the statuses and trends of wildlife communities in montane forests, such as those in Yushan National Park (YSNP), Taiwan. Integrating passive acoustic monitoring (PAM) with an automated sound identifier, a long-term biodiversity monitoring project containing six PAM stations, was launched in YSNP in January 2020 and is currently ongoing. SILIC, an automated wildlife sound identification model, was used to extract sounds and species information from the recordings collected. Animal vocal activity can reflect their breeding status, behaviour, population, movement and distribution, which may be affected by factors, such as habitat loss, climate change and human activity. This massive amount of wildlife vocalisation dataset can provide essential information for the National Park's headquarters on resource management and decision-making. It can also be valuable for those studying the effects of climate change on animal distribution and behaviour at a regional or global scale. To our best knowledge, this is the first open-access dataset with species occurrence data extracted from sounds in soundscape recordings by artificial intelligence. We obtained seven bird species for the first release, with more bird species and other taxa, such as mammals and frogs, to be updated annually. Raw recordings containing over 1.7 million one-minute recordings collected between the years 2020 and 2021 were analysed and SILIC identified 6,243,820 vocalisations of seven bird species in 439,275 recordings. The automatic detection had a precision of 0.95 and the recall ranged from 0.48 to 0.80. In terms of the balance between precision and recall, we prioritised increasing precision over recall in order to minimise false positive detections. In this dataset, we summarised the count of vocalisations detected per sound class per recording which resulted in 802,670 occurrence records. Unlike data from traditional human observation methods, the number of observations in the Darwin Core "organismQuantity" column refers to the number of vocalisations detected for a specific bird species and cannot be directly linked to the number of individuals.We expect our dataset will be able to help fill the data gaps of fine-scale avian temporal activity patterns in montane forests and contribute to studies concerning the impacts of climate change on montane forest ecosystems on regional or global scales.

Design, establishment, analysis, and quality control of a high-precision reference frame in Cortes de Pallás (Spain)

A high-precision geodetic reference frame was required in Cortes de Pallás (Spain) to undertake a long-term deformation monitoring project. Involving distances up to 2000 m, the aimed accuracy was 1 mm and 3 mm for horizontal and vertical components, respectively. Such a high precision is necessary to detect possible displacements of selected points on a critical rocky area in a short period of time, i.e., 2 or 3 years, and also to provide ground control for the integration of precise 3D models periodically obtained by remote sensing techniques. Considering the historical geotechnical problems of the area, the possible influence of the hydroelectric power plant, and the peculiar orography of the zone, a proper analysis of the stability is crucial if the reference frame is to be used for rigorous over-time deformation monitoring. This paper describes the deformation monitoring of a 10-pillar geodetic network which was measured from 2018 to 2020 by using a sub-millimetric Mekometer ME5000 (0.2 mm + 0.2 ppm) along with a demanding observing methodology which includes a network of data loggers for temperature, humidity, and air pressure as well as proper calibration of sensors and instruments to prevent potential inconsistencies between the scale of the network and the unit of length of the International System (SI meter). The results demonstrated that the chosen methodology yielded the aimed accuracy. However, using such a high precision methodology entails the problem that small displacements of only 1 or 2 mm are significantly detected as deformations by conventional deformation analysis and then it arises the problem of finding a subset of stable points for a rigorous datum realization when all the points seem to displace. This general problem is analyzed in the particular case of Cortes de Pallás, where a balanced mix of deformation analysis and technical decisions was eventually adopted to define a precise and stable reference frame for rigorous over-time deformation monitoring.

Science and Public Engagement in National Parks: Examples and Advice from Young Scientists

Science and Public Engagement in National Parks: Examples and Advice from Young Scientists

Cold winters drive consistent and spatially synchronous 8-year population cycles of cabbage stem flea beetle.

Population cycles have been observed in mammals as well as insects, but consistent population cycling has rarely been documented in agroecosystems and never for a beetle. We analysed the long-term population patterns of the cabbage stem flea beetle Psylliodes chrysocephala in winter oilseed rape over 50 years. Psylliodes chrysocephala larval density from 3045 winter oilseed rape fields in southern Sweden showed strong 8-year population cycles in regional mean density. Fluctuations in larval density were synchronous over time across five subregional populations. Subregional mean environmental variables explained 90.6% of the synchrony in P. chrysocephala populations at the 7-11year time-scale. The number of days below -10°C showed strong anti-phase coherence with larval densities in the 7-11year time-scale, such that more cold days resulted in low larval densities. High levels of the North Atlantic Oscillation weather system are coherent and anti-phase with cold weather in Scania, Sweden. At the field-scale, later crop planting date and more cold winter days were associated with decreased overwintering larval density. Warmer autumn temperatures, resulting in greater larval accumulated degree days early in the season, increased overwintering larval density. Despite variation in environmental conditions and crop management, 8-yearcycles persisted for cabbage stem flea beetle throughout the 50 years of data collection. Moran effects, influenced by the North Atlantic Oscillation weather patterns, are the primary drivers of this cycle and synchronicity. Insect pest data collected in commercial agriculture fields is an abundant source of long-term data. We show that an agricultural pest can have the same periodic population cycles observed in perennial and unmanaged ecosystems. This unexpected finding has implications for sustainable pest management in agriculture and shows the value of long-term pest monitoring projects as an additional source of time-series data to untangle the drivers of population cycles.

SLAM Project - Long Term Ecological Study of the Impacts of Climate Change in the natural forests of Azores: V - New records of terrestrial arthropods after ten years of SLAM sampling.

A long-term study monitoring arthropods (Arthropoda) is being conducted since 2012 in the forests of Azorean Islands. Named "SLAM - Long Term Ecological Study of the Impacts of Climate Change in the natural forest of Azores", this project aims to understand the impact of biodiversity erosion drivers in the distribution, abundance and diversity of Azorean arthropods. The current dataset represents arthropods that have been recorded using a total of 42 passive SLAM traps (Sea, Land and Air Malaise) deployed in native, mixed and exotic forest fragments in seven Azorean Islands (Flores, Faial, Pico, Graciosa, Terceira, São Miguel and Santa Maria). This manuscript is the fifth data-paper contribution, based on data from this long-term monitoring project. We targeted taxa for species identification belonging to Arachnida (excluding Acari), Chilopoda, Diplopoda, Hexapoda (excluding Collembola, Lepidoptera, Diptera and Hymenoptera (but including only Formicidae)). Specimens were sampled over seven Azorean Islands during the 2012-2021 period. Spiders (Araneae) data from Pico and Terceira Islands are not included since they have been already published elsewhere (Costa and Borges 2021, Lhoumeau et al. 2022). We collected a total of 176007 specimens, of which 168565 (95.7%) were identified to the species or subspecies level. For Araneae and some Hemiptera species, juveniles are also included in this paper, since the low diversity in the Azores allows a relatively precise species-level identification of this life-stage. We recorded a total of 316 named species and subspecies, belonging to 25 orders, 106 families and 260 genera. The ten most abundant species were mostly endemic or native non-endemic (one Opiliones, one Archaeognatha and seven Hemiptera) and only one exotic species, the Julida Ommatoiulusmoreleti (Lucas, 1860). These ten species represent 107330 individuals (60%) of all sampled specimens and can be considered as the dominant species in the Azorean native forests for the target studied taxa. The Hemiptera were the most abundant taxa, with 90127 (50.4%) specimens. The Coleoptera were the most diverse with 30 (28.6%) families.We registered 72 new records for many of the islands (two for Flores, eight for Faial, 24 for Graciosa, 23 for Pico, eight for Terceira, three for São Miguel and four for Santa Maria). These records represent 58 species. None of them is new to the Azores Archipelago. Most of the new records are introduced species, all still with low abundance on the studied islands. This publication contributes to increasing the baseline information for future long-term comparisons of the arthropods of the studied sites and the knowledge of the arthropod fauna of the native forests of the Azores, in terms of species abundance, distribution and diversity throughout seasons and years.

Microsatellite Characterization and Panel Selection for Brown Bear (Ursus arctos) Population Assessment.

An assessment of the genetic diversity and structure of a population is essential for designing recovery plans for threatened species. Italy hosts two brown bear populations, Ursus arctos marsicanus (Uam), endemic to the Apennines of central Italy, and Ursus arctos arctos (Uaa), in the Italian Alps. Both populations are endangered and occasionally involved in human-wildlife conflict; thus, detailed management plans have been in place for several decades, including genetic monitoring. Here, we propose a simple cost-effective microsatellite-based protocol for the management of populations with low genetic variation. We sampled 22 Uam and 22 Uaa individuals and analyzed a total of 32 microsatellite loci in order to evaluate their applicability in individual identification. Based on genetic variability estimates, we compared data from four different STR marker sets, to evaluate the optimal settings in long-term monitoring projects. Allelic richness and gene diversity were the highest for the Uaa population, whereas depleted genetic variability was noted for the Uam population, which should be regarded as a conservation priority. Our results identified the most effective STR sets for the estimation of genetic diversity and individual discrimination in Uam (9 loci, PIC 0.45; PID 2.0 × 10-5), and Uaa (12 loci, PIC 0.64; PID 6.9 × 10-11) populations, which can easily be utilized by smaller laboratories to support local governments in regular population monitoring. The method we proposed to select the most variable markers could be adopted for the genetic characterization of other small and isolated populations.

Long-term monitoring projects of Brazilian marine and coastal ecosystems.

Biodiversity assessment is a mandatory task for sustainable and adaptive management for the next decade, and long-term ecological monitoring programs are a cornerstone for understanding changes in ecosystems. The Brazilian Long-Term Ecological Research Program (PELD) is an integrated effort model supported by public funds that finance ecological studies at 34 locations. By interviewing and compiling data from project coordinators, we assessed monitoring efforts, targeting biological groups and scientific production from nine PELD projects encompassing coastal lagoons to mesophotic reefs and oceanic islands. Reef environments and fish groups were the most often studied within the long-term projects. PELD projects covered priority areas for conservation but missed sensitive areas close to large cities, as well as underrepresenting ecosystems on the North and Northeast Brazilian coast. Long-term monitoring projects in marine and coastal environments in Brazil are recent (<5 years), not yet integrated as a network, but scientifically productive with considerable relevance for academic and human resources training. Scientific production increased exponentially with project age, despite interruption and shortage of funding during their history. From our diagnosis, we recommend some actions to fill in observed gaps, such as: enhancing projects' collaboration and integration; focusing on priority regions for new projects; broadening the scope of monitored variables; and, maintenance of funding for existing projects.

Habitat associations of imperilled fishes after conservation intervention in the Cape Fold Ecoregion, South Africa.

The aim of this study was to examine the habitat associations of a native cyprinid community of the recovering Rondegat River in the Cape Fold Ecoregion of South Africa as part of a long-term native fish abundance monitoring project. Relative abundance data were extracted from underwater video camera footage across the longitudinal gradient of the river in three sampling instances. Using multivariate methods the authors assessed community composition with respect to habitat, its overlap with a protected area and species-specific abiotic predictors of relative abundance. Distance from the uppermost site in the river was the most significant predictor of species abundance, indicating spatial segregation and varying overlap between species. The protected status of sites in the upper reaches, vegetated substrates and the size of individual sites were the most impactful on the relative abundance of the endangered fiery redfin Pseudobarbus phlegethon. The results of this study indicate that underwater video monitoring is an effective and low-cost approach that can inform conservation recommendations. Reducing agricultural runoff and sedimentation in the lower reaches may be useful further interventions to maintain key habitats of submerged vegetation.

Lakes and trees as climate and environment archives: the TERENO Northeastern German Lowland Observatory

Abstract. Robust reconstruction of past climate and environmental change based on proxy data obtained from natural archives requires an in-depth understanding of the processes and mechanisms that form and determine these proxies. Here we present comprehensive long-term monitoring projects for seasonally laminated (varved) lake sediments and tree rings in the northern German lowlands. The two monitoring sites are located in the nature park Nossentiner/Schwinzer Heide (Tiefer See) and in the Müritz National Park (tree rings) and are an integral part of the Helmholtz TERrestrial ENvironmental Observatories (TERENO) infrastructure initiative. Both sites are located in the close vicinity of moraine deposits of the main ice advance of the Pomeranian phase of the Weichselian glaciation. This field guide provides an introduction to the local morphologies and landscapes as well as details of the monitoring concepts and some selected results.

Tissue loss disease outbreak significantly alters the Southeast Florida stony coral assemblage

A stony coral tissue loss disease (SCTLD) outbreak, first widely reported in 2014 in the Southeast Florida Ecosystem Conservation Area (Coral ECA), has continued to impact stony coral communities for more than seven years. Here, we utilize long-term (2012-2020) annual monitoring data from the Southeast Florida Reef Evaluation and Monitoring Project (SECREMP) to assess the impact of the SCTLD outbreak on the stony coral assemblage as well as spatiotemporal and ecological associated variation. SECREMP examines 22 permanent sites distributed along Florida’s Coral Reef from Miami-Dade County north to Martin County, Florida. We expand upon previously documented disease event-related regional impacts. Coral ECA SCTLD prevalence was greatest in 2016 coinciding with significant declines in coral live tissue area (LTA). Even though by 2018 SCTLD prevalence had dropped to &amp;lt; 1% and significant annual LTA declines were no longer recorded, upwards of 59% of stony coral total LTA in the Coral ECA was lost between 2015-2018. In this study, SCTLD was observed across all habitats and affected 11 stony coral species. Colony size did not preclude infection or mortality, with 25% of all infections occurring on colonies 5-14 cm in diameter. The indiscriminate nature of the disease and lack of size refugia has altered the stony coral population structure and assemblage composition. Since 2016, the coral assemblage has shifted towards smaller colonies, with a significant decrease in mean colony size. Juvenile corals, &amp;lt; 4 cm diameter, of many reef building, structurally-complex species were rarely documented, while eurytopic, generalist species dominated juvenile abundance. Although significant losses, altering ecosystem function, were documented, all species recorded prior to the disease event were present, albeit some only as juveniles. Our study adds to the growing body of evidence of the severity of the disease outbreak and precarious state of the stony coral assemblage in the Coral ECA. We show long-term monitoring projects provide invaluable opportunities to capture such spatiotemporal changes in coral assemblages and may identify potential indicators of recovery. While no stony coral species were completely lost from the monitored assemblage, the likelihood of recovery, to even a pre-outbreak state, is limited without immediate action addressing development related local stressors and climate change related global stressors.

The importance of evaluating standard monitoring methods: Observer bias and detection probabilities for moose pellet group surveys.

Counting is not always a simple exercise. Specimens can be misidentified or not detected when they are present, giving rise to unidentified sources of error. Deer pellet group counts are a common method to monitor abundance, density, and population trend. Yet, detection errors and observer bias could introduce error into sometimes very large (spatially, temporally) datasets. For example, in Scandinavia, moose (Alces alces) pellet group counts are conducted by volunteer hunters and students, but it is unknown how much uncertainty observer error introduces into these datasets. Our objectives were to 1) estimate the detection probability of moose pellet groups; 2) identify the primary variables leading to detection errors including prior observer experience; and 3) compare density estimates using single and double observer counts. We selected a subset of single observer plots from a long-term monitoring project to be conducted as dependent double observer surveys, where primary and secondary observers worked simultaneously in the field. We did this to quantify detection errors for moose pellet groups, which were previously unknown in Scandinavia, and to identify covariates which introduced variation into our estimates. Our study area was in the boreal forests of southern Norway where we had a nested grid of 100-m2 plots that we surveyed each spring. Our observers were primarily inexperienced. We found that when pellet groups were detected by the primary observer, the secondary observer saw additional pellet groups 42% of the time. We found search time was the primary covariate influencing detection. We also found density estimates from double observer counts were 1.4 times higher than single observer counts, for the same plots. This density underestimation from single observer surveys could have consequences to managers, who sometimes use pellet counts to set harvest quotas. We recommend specific steps to improve future moose pellet counts.

Construction and Live Load Behavior of a Skewed Steel I-Girder Bridge

As part of a long-term monitoring project, a two-span continuous steel I-girder bridge (skewed 41° with seat-type abutments) was instrumented and evaluated in the field during construction and after the bridge was in service. This paper discusses data from when the first stage (of a three-stage sequence) was constructed and initially opened to traffic. Girders and cross-frames were instrumented with strain gauges using a data acquisition system with a high sampling frequency (up to 20 Hz). Data collection began just before deck placement, and a series of live load tests was then conducted on the completed Stage I (half of the bridge) using a loaded truck. Three-dimensional finite element analyses were carried out to provide enhanced understanding of bridge behavior. Good agreement was observed between the numerical simulation results and the field monitoring data for both deck placement and live load testing. A slight inconsistency between numerical simulation and field measurement data at one girder section and an adjacent cross-frame indicated an unexpected local site condition, which was confirmed through a targeted field inspection. Live load distribution factors used during design conservatively overestimate bridge girder strong-axis bending response under live load (by around 50%). Maximum flange lateral bending stresses of 6.3 MPa (0.9 kips per square inch [ksi]) and 2.5 MPa (0.4 ksi) were observed during deck placement and truck tests, respectively. In addition, out-of-plane response of 10.6 MPa (1.5 ksi) was observed at girder web plates under concrete dead load.

Unoccupied aerial video (UAV) surveys as alternatives to BRUV surveys for monitoring elasmobranch species in coastal waters

Abstract Effective conservation strategies are founded by baseline information on abundance and diversity estimates. Method choice can influence the success of baseline surveys as method performance is variable and needs to be selected based on habitat and taxa. Here, we assess the suitability of unoccupied aerial vehicle (UAV) surveys, specifically multi-rotor “drones”, and baited remote underwater video (BRUV) surveys in shallow-water habitats to quantify elasmobranch abundance and diversity in the Saudi Arabian central Red Sea. Our results show that the number of elasmobranchs h−1 observed using UAV surveys exceeded that of BRUV surveys by two orders of magnitude, indicating that the increased spatial coverage of UAV surveys is beneficial for long-term monitoring projects. BRUV surveys detected a greater number of species within reef habitats, whereas UAV surveys detected a greater number of species within sandflat habitats, indicating the value of multi-method approaches for regional biodiversity studies. Here, we provide the first insight into elasmobranchs associated with sandflat habitats in Saudi Arabia, emphasising the importance of these habitats to stingrays and the need for further information on elasmobranch habitat use to better inform management and conservation efforts in the face of rapid coastal developments across the Red Sea.

A COMBINED APPROACH FOR LONG-TERM MONITORING OF BENTHOS IN ANTARCTICA WITH UNDERWATER PHOTOGRAMMETRY AND IMAGE UNDERSTANDING

Abstract. Long-term monitoring projects are becoming more than ever crucial in assessing the effects of climate change on marine communities, especially in Antarctica, where these changes are expected to be particularly dramatic. Detailed studies of the Antarctic benthos are in fact particularly important for a better understanding of benthos dynamics and potential climate-driven shifts. Here, due to the extreme fragility of benthic communities, non-destructive techniques represent the best solution in long-term monitoring programs. In this paper we report new results from 2017, 2018, 2019 photogrammetric campaigns within the Italian National Antarctic Research Program (PNRA). A new protocol of data acquisition and multi-temporal processing that provides co-registered 3D point clouds between the three years without control points nor direct georeferencing methods is presented. This is achieved by adding a level of image understanding leveraging semantic segmentation with convolutional neural network (CNN) of the benthic features. Slow growing (estimated less than a mm per year) organisms, such as Corallinales (Rhodophyta algae), represent a natural stable pattern, leveraged to automatically orient in the same reference system the photogrammetric surveys of different epochs. This approach is also proved to be effective in improving the orientation of adjacent strips acquired within the same campaign. Within the paper an in depth analysis of the achieved results shows the effectiveness of the implemented procedure.