Management Of Wild Populations Research Articles

Gene-Based Therapy: A New Approach to Feline Induced Sterilization?

Feline population control remains a concern as to whether it is intended for the short- or long-term. Induced sterilization of felids is critical in the case of feral, free-roaming cats, or the management of wild populations in Zoos or sanctuaries. This narrative review explores the shifting paradigm in induced sterilization methods, driven by the development of gene editing approaches recently applied to control felid reproductive activity. Although gene therapy approaches have gained attention as alternatives to more traditional methods, their clinical applications remain in the realm of thought. The objective of this study was to provide a comprehensive overview of the current state and most recent advances in gene-based contraception options, consolidate current research and evidence, and share some considerations on its potential effectiveness, advantages or limitations, and implications for animal welfare and population control strategies. Gene-based contraception therapy tested in felines, targeting the AMH pathway, was unable to suppress the estrous cycle and follicular development. However, at an experimental level, preliminary results hint at the need to change towards different molecular targets. Moreover, their side effects remain largely unknown, and several questions remain unanswered, such as the regularity of treatment applications or cost.

Do hihi lose access to supplemental feeders because of the presence of korimako?

ABSTRACT Supplemental feeding is now a ubiquitous and effective tool in the conservation management of wild populations. On Tiritiri Matangi Island, the persistence of the hihi (Notiomystis cincta) population depends on constant food supplementation. However, the more dominant korimako (Anthornis melanura) can also access these feeders. To understand whether korimako may be limiting hihi access to the feeders, we used an observational study to quantify the co-occurrences at feeders and potential for resource partitioning and competitive exclusion of males and females of both species. We measured hihi and korimako visits to sugar-water feeders and the frequency of territorial interactions during the non-breeding and breeding seasons. We found that male korimako were the most frequent visitors (116 ± 7 visits h−1), followed by male hihi (51 ± 3 visits h−1), female hihi (47 ± 3 visits h−1), then female korimako (6 ± 1 visits h−1). In general, visits positively correlated between each species and sex across months. Few intra- and interspecific aggressive interactions were observed in the non-breeding season and early breeding season. We found no evidence that hihi were being excluded from the supplemental feeders by korimako, potentially from the high visitation rates making territorial and aggressive interactions ineffectual.

Ex situ germplasm collections of exceptional species are a vital part of the conservation of Australia's national plant treasures

Societal Impact StatementConservation seed banks maintain collections of many seed‐bearing plant species, providing germplasm and data to support management of wild populations. However, a proportion of plant species produce seeds that are difficult to collect, dry, store and utilise; these are known as ‘exceptional’ species. Here we tested a framework for identifying exceptional species, to document examples and provide case studies within the Australian flora. We present a workflow that may be used to identify additional exceptional species, and direct efforts to establish appropriate collection types (seeds and/or living collections, tissue culture or cryopreservation) for their ex situ conservation.SummarySeed banking is well established to contribute to the conservation of many seed‐bearing plant species ex situ for future use in restoration, translocation, agriculture and horticulture. In Australia, over 67% of currently listed threatened plants are represented in conservation seed banks. However, there are challenges to conserving the full extent of plant diversity in seed banks, with growing recognition that we need to think beyond conventional seed banking methods to conserve ‘exceptional’ plant species that are difficult to collect, store and germinate. We examine how the framework for identification of such species can be applied to the Australian flora, using examples from the recently published guidelines for ‘Plant Germplasm Conservation in Australia’ and case studies and data arising from the Australian Academy of Science Fenner Conference on the Environment ‘Exceptional Times, Exceptional Plants’. We present a workflow to assist conservation decision‐makers and practitioners in identifying exceptional species and overcoming barriers to storage of germplasm, enabling appropriate ex situ collection types to be established via seeds, living collections, tissue culture, cryopreservation or a combination of these. Australia's seed conservation sector continues to expand, with increasing expertise, facilities and networks established to conserve a diversity of plant species; however, resolving the challenges relating to each exceptionality factor requires significantly more time, labour and collaboration than current capacity allows. Understanding the barriers to conservation and production of healthy plants, via germination or other methods of propagation, is a critical component of conserving species long‐term and ultimately returning plants to the landscape.

Chromosome-level genome assembly and population genomic analysis reveal evolution and local adaptation in common hairfin anchovy (Setipinna tenuifilis).

Understanding the genetic structure and the factors associated with adaptive diversity has significant implications for the effective management of wild populations under threat from overfishing and climate change. The common hairfin anchovy (Setipinna tenuifilis) is an economically and ecologically important pelagic fish species, spanning a broad latitudinal gradient along marginal seas of the Northwest Pacific. In this study, we constructed the first reference genome of S. tenuifilis using PacBio long reads and high-resolution chromosome conformation capture (Hi-C) technology. The assembled genome was 798.38 Mb with a contig N50 of 1.43 Mb and a scaffold N50 of 32.42 Mb, which were anchored onto 24 pseudochromosomes. A total of 22,019 genes were functionally annotated, which accounted for 95.27% of the predicted protein-coding genes. Chromosomal collinearity analysis revealed chromosome fusion or fission events in Clupeiformes species. Three genetic groups of S. tenuifilis were revealed along the Chinese coast using restriction site-associated DNA sequencing (RADseq). We investigated the influence of four bioclimatic variables as potential drivers of adaptive divergence in S. tenuifilis, suggesting that these environmental variables, especially sea surface temperature, may play important roles as drivers of spatially varying selection for S. tenuifilis. We also identified candidate functional genes underlying adaptive mechanisms and ecological tradeoffs using redundancy analysis (RDA) and BayeScan analysis. In summary, this study sheds light on the evolution and spatial patterns of genetic variation of S. tenuifilis, providing a valuable genomic resource for further biological and genetic studies on this species and other closely related Clupeiformes.

Genetic Structure and Diversity in Wild and Cultivated Populations of the Mangrove Oyster Crassostrea gasar from Southern Brazil.

The mangrove oyster (Crassostrea gasar) is Brazil's second most cultured species and presents a high potential for aquaculture. However, artificial selection in a highly fecund species and significant variance in reproductive success can result in the loss of genetic diversity and increases the inbreedingrate, especially in cultivated populations. In this study, we investigated the genetic structure and diversity of C. gasar in wild and cultivated populations using 14 microsatellites. Spatial genetic comparisons revealed the existence of two main genetic groups of C. gasar, one comprising the population in cultivation and the other formed by wild populations along the southern and southeastern Braziliancoasts. Although no common genetic structure exists among wild populations, it is possible to observe a distribution gradient based on discriminant analysis of principal components consistent with their geographic distribution. However, it is insufficient to differentiate them genetically. Despite artificial reproduction, thegenetic diversity values of the cultivated population remained relatively high and did not show areduction. Therefore, monitoring the cultivated population and establishing reference values for genetic diversity will allow the adoption of strategies both for the viability of the cultivated population and the management of wild populations.

Publication and use of genetic tools in conservation management applications—A systematic review

Abstract Genetics tools are used in applied conservation management for taxonomic identification, delineation of management units, management of wild populations, captive breeding and reintroduction and control of invasive species, disease and hybridisation. To assess the extent to which genetic tools are being used for applied conservation management, we conducted a systematic literature review of over 53,767 papers focussing on wildlife research that reported results on species delineation, translocations and population augmentation. We synthesised information on papers that used genetics tools in an expressly applied manner across all wildlife species. We found that the application of genetics tools in conservation management was biased towards fishes, mammals and birds and northern hemisphere locations, especially the United States and Europe. Despite genetics tools being a highly published topic, it was difficult to find published applications of these tools in both the primary and the grey literature. Of the 115 papers on 152 species that could be considered an applied use of a genetics tool expressly for conservation management, only 49 had definable applied outcomes. The remaining 66 made recommendations, but it was often unclear if the recommendations were ever used to make conservation management decisions because of the time‐lag between publication of the initial recommendation and publication of the results of the use of the tool in a conservation management situation, as well as the lack of dissemination in the primary literature. Our study highlights the relative low publication rate of applications of genetics tools compared to the general conservation genetics field. These tools appear to have either a low percentage of translations into publication (‘conservation genetics publishing gap’) or a poor uptake among wildlife conservation managers (‘conservation genetics gap’)—the two are indistinguishable in this review. Policy implications. Conservation genetics tools must be brought to the forefront of conservation policy and management. Users should support the use of systems and accessible databases to increase the uptake of genetics tools for conservation in applied management decisions for wildlife, reducing barriers to disseminating the results to other end users and interested parties.

Genetic Diversity and Population Structure of Hemiculter leucisculus (Basilesky, 1855) in Xinjiang Tarim River.

Hemiculter leucisculus is an invasive fish and widely distributed in the Xinjiang Tarim River. In this study, RAD-seq was used to explore the genetic diversity and population subgroup structure of H. leucisculus in the Tarim River and develop relevant Simple Sequence Repeat (SSR) markers. The study collected 40 samples distributed at four different sites of the Tarim River. A total of 7,291,260 single nucleotide polymorphisms (SNPs) were obtained. The genetic diversity results showed that the population genetic diversity level of H. leucisculus was low. The population pairwise FST values ranged from 0.231 to 0.258, indicating that there was moderate genetic differentiation among these populations. AMOVA showed that the genetic variation within populations accounted for 92.31% of the total variation. The principal component analysis (PCA) and neighbor joining (NJ) tree revealed that the four populations could be separated into two clusters (upper-middle and downstream populations) and the individuals from Taitema Lake (TTMH) showed differences and had a bigger geographic distance than the others. There is the probability that the H. leucisculus from Bosten Lake entered Taitema Lake to breed and then expanded into the Tarim River due to the water diversion projects in location. In addition, 147,705 SSRs loci were detected and 22,651 SSR primer pairs were developed. This study will contribute to providing valuable molecular data for the management of wild populations, marker-assisted selection and resource exploitation of H. leucisculus.

Idea paper: Controlling trait adaptation to decrease population densities for conservation and management

AbstractEcologists and evolutionary biologists have revealed that adaptive microevolution (i.e., allele frequency changes through time) and behavioral changes occur rapidly enough to affect contemporary ecological dynamics, and we can consider rapid adaptation for better conservation and management of wild populations. However, previous studies tended to focus on adaptation that increases population densities (e.g., evolutionary rescue), and did not pay attention to adaptation that decreases population densities (e.g., evolutionary suicide). Here, we demonstrate that controlling trait adaptation may be potentially important for decreasing population densities. One possibility is introducing “selfish” genotypes to populations. If the genotypes increase their reproductive success at the expense of population growth (e.g., cheaters in subsocial ants or coercive males in damselflies), we can decrease population densities (intraspecific adaptation load). The other possible option is diverting trait values of animals from the value that maximizes population growth (ecological trap). For example, we may be able to change behavior of a deer population by hunting so that they will not approach the best habitat with ample resources (landscape of fear). Then, we can consider the optimal allocation of our effort to directly decrease their population densities and control their trait values. However, we should carefully conduct controlling trait adaptation because it may result in unintended outcomes through modified genetic compositions and behaviors, such as increasing genetic variation of the focal population that enhances adaptation to changing environments by introducing selfish genotypes or a transient increase of population densities by modified behaviors.

Whisker growth in Tasmanian devils (Sarcophilus harrisii) and applications for stable isotope studies

AbstractIndividual longitudinal records of diet, movement, and physiological state of endangered Tasmanian devils (Sarcophilus harrisii) are needed for effective management of wild populations, yet most traditional techniques are expensive or labor‐intensive. Stable isotope analysis of inert tissue, such as vibrissae (whiskers), provides a viable and minimally invasive solution to chronologically record the foraging ecology and habitat use of individuals. Species‐specific information on whisker growth (i.e., time‐position growth of isotopic signatures), retention time, and arrangement on the face is required before the implementation of stable isotope analysis in wild populations. Here, whiskers of six captive Tasmanian devils were internally marked with 13C‐ and 15N‐labeled glycine at three‐month intervals followed by isotopic analysis of the longest whisker to provide a time stamp for whisker growth and estimate retention time. Intradermal and extradermal lengths of wild Tasmanian devil whiskers were used to assess the arrangement and relative length of whiskers on the face. We found that whiskers can record at least nine months of an animal's ecological history and that whisker growth is not linear, the growth gradually slows down as the whisker lengthens. Our findings demonstrate that sequentially sampled whiskers have the potential to track monthly and seasonal isotopic changes of an individual animal in the wild, both within its historical range and in areas to which it has recently been introduced. Such information can be used to identify temporal shifts in habitat and prey preferences within populations and help select suitable individuals for translocations. We recommend that the longest mystacial whiskers, positioned posteriorly at the third and fourth row, should be preferentially used for stable isotope studies in this species. The timeframe represented by the root of the whisker (˜3–63 d) can be used to adjust the base of cut whiskers to the correct time period.

Taking full advantage of the diverse assemblage of data at hand to produce time series of abundance: a case study on Atlantic salmon populations of Brittany

Estimation of abundance with wide spatiotemporal coverage is essential to the assessment and management of wild populations. But, in many cases, data available to estimate abundance time series have diverse forms, variable quality over space and time and they stem from multiple data collection procedures. We developed a hierarchical Bayesian modelling (HBM) approach that take full advantage of the diverse assemblage of data at hand to estimate homogeneous time series of abundances irrespective of the data collection procedure. We apply our approach to the estimation of adult abundances of 18 Atlantic salmon (Salmo salar) populations of Brittany (France) from 1987 to 2017 using catch statistics, environmental covariates, and fishing effort. Additional data of total or partial abundance collected in four closely monitored populations are also integrated into the analysis. The HBM framework allows the transfer of information from the closely monitored populations to the others. Our results reveal no clear trend in the abundance of adult returns in Brittany over the period studied.

Lake sturgeon (Acipenser fulvescens) annual adult survival estimated from acoustic telemetry

Survival of adult fishes is critical to the conservation and management of wild populations, particularly for long-lived, slow to reproduce species. Most sturgeon species are of conservation concern, but their long lifespans and large ranges have made estimation of adult survival rates challenging. In this study, acoustic telemetry was used to track 205 lake sturgeon (Acipenser fulvescens) tagged in the St. Clair and Detroit rivers of the Laurentian Great Lakes over seven years (2012–2019). The objective of this study was to determine if annual survival was related to sex, size, tagging location (river), or year post-tagging using Cormack-Jolly-Seber (CJS) models. Annual survival was high among all seven years (range of point estimates: 95–99%) and did not differ based on sex, tagging year, size at time of tagging, or tagging location. Lake sturgeon detection probability on acoustic receivers was high each year (range of point estimates: 82–99%) and increased as the number of receivers in the system increased. High survival rates of lake sturgeon were consistent with levels thought required for lake sturgeon to be self-sustaining in the St. Clair – Detroit river system. Our application of acoustic telemetry detections as input to CJS models demonstrated the usefulness of this approach and should be considered for population assessment studies throughout the Great Lakes and beyond.

A novel framework for evaluating in situ breeding management strategies in endangered populations.

Conservation breeding management aims to reduce inbreeding and maximize the retention of genetic diversity in endangered populations. However, breeding management of wild populations is still rare, and there is a need for approaches that provide data-driven evidence of the likelihood of success of alternative in situ strategies. Here, we provide an analytical framework that uses in silico simulations to evaluate, for real wild populations, (i) the degree of population-level inbreeding avoidance, (ii) the genetic quality of mating pairs, and (iii) the potential genetic benefits of implementing two breeding management strategies. The proposed strategies aim to improve the genetic quality of breeding pairs by splitting detrimental pairs and allowing the members to re-pair in different ways. We apply the framework to the wild population of the Critically Endangered helmeted honeyeater by combining genomic data and field observations to estimate the inbreeding (i.e., pair-kinship) and genetic quality (i.e., Mate Suitability Index) of all mating pairs for seven consecutive breeding seasons. We found no evidence of population-level inbreeding avoidance and that ~91.6% of breeding pairs were detrimental to the genetic health of the population. Furthermore, the framework revealed that neither proposed management strategy would significantly improve the genetic quality or reduce inbreeding of the mating pairs in this population. Our results demonstrate the usefulness of our analytical framework for testing the efficacy of different in situ breeding management strategies and for making evidence-based management decisions.

Effect of Fungicide Application on Lowbush Blueberries Soil Microbiome.

Lowbush blueberries (Vaccinium sp.) are perennial crops produced throughout eastern Canada and Maine through management of wild populations. Given the constraints of this cropping system, the application of fungicides is critical to reducing disease pressure and ensuring consistent yields. However, as plant health is intertwined with soil health, it is important to consider the impact of fungicides on microbial communities. To understand the effects of fungicides in this context, bacterial and fungal microbial communities from fungicide-treated plots, as well as untreated control plots (UTG) were analyzed using amplicon sequencing. The fungicides, considered collectively as a combined treatment group (CTG), lead to a loss in fungal richness. One family, Clavariaceae, had an increased abundance under prothioconazole relative to UTG. This finding may be significant as taxa in Clavariaceae have been thought to potentially form ericoid mycorrhizae with Vaccinium. Five functional pathways and 74 enzymes differed significantly in relative abundance between CTG and UTG including enzymes associated with soil nutrient cycles. Most notably, enzymes corresponding to the breakdown of halogen-organic compounds had an increased abundance in CTG, suggesting bacterial fungicide degradation. Some enzymes associated with soil nutrient cycles differed significantly, possibly implying changes to nutrient pathways due to fungicide treatment.

High genetic structure between natural populations of bighead catfish Clarias macrocephalus (Günther, 1864) from the Mekong Delta and Peninsular Malaysia

The tropical freshwater bighead catfish Clarias macrocephalus is widely distributed in Southeast Asia and is economically important in both the aquaculture and fisheries industries. In the current study, eight polymorphic microsatellite markers were employed to evaluate the genetic variation of 15 C. macrocephalus populations from Peninsular Malaysia, and the Mekong Delta populations of Cambodia and Vietnam. Overall, the number of alleles in C. macrocephalus populations ranged from 1 to 25 alleles. In general, genetic diversity was higher in the mainland populations (Cambodia, HE = 0.761 to 0.813 and Vietnam, HE = 0.759 to 0.789 with mean number of alleles of 10.13–13.88) compared to Peninsular Malaysia (HE = 0.519 to 0.699 with mean number of alleles of 4.5–10.75). High linkage disequilibrium and deviation from HWE suggest inbreeding in most Peninsular Malaysia populations which was also reflected by significant FIS values (0.217 to 0.410, p < 0.05). All pairwise FST (p < 0.05) values were significant. No evidence of bottlenecks was detected among all populations. The 15 populations formed two evolutionary units; Peninsular Malaysia versus the Mekong Delta-Cambodia and Vietnam. The findings from this study will serve as a reference for a systematic aquaculture programme and the conservation and management of wild populations of C. macrocephalus.

Integrating high-speed videos in capture-mark-recapture studies of insects.

Capture–mark–recapture (CMR) studies have been used extensively in ecology and evolution. While it is feasible to apply CMR in some animals, it is considerably more challenging in small fast‐moving species such as insects. In these groups, low recapture rates can bias estimates of demographic parameters, thereby handicapping effective analysis and management of wild populations. Here, we use high‐speed videos (HSV) to capture two large dragonfly species, Anax junius and Rhionaeschna multicolor, that rarely land and, thus, are particularly challenging for CMR studies. We test whether HSV, compared to conventional “eye” observations, increases the “resighting” rates and, consequently, improves estimates of both survival rates and the effects of demographic covariates on survival. We show that the use of HSV increases the number of resights by 64% in A. junius and 48% in R. multicolor. HSV improved our estimates of resighting and survival probability which were either under‐ or overestimated with the conventional observations. Including HSV improved credible intervals for resighting rate and survival probability by 190% and 130% in A. junius and R. multicolor, respectively. Hence, it has the potential to open the door to a wide range of research possibilities on species that are traditionally difficult to monitor with distance sampling, including within insects and birds.

Understanding the Phylogenetics of Indian Hoolock Gibbons: Hoolock hoolock and H. leuconedys

Information about the taxonomy and geographical distribution of a species is essential to understand its evolution and for conservation efforts. The phylogeny of the Hylobatidae remains unclear. India is reported to have one species of Hoolock gibbon (Hoolock hoolock) but a recent study based on pelage colour suggested that another species, H. leuconedys, occurs in the Mishmi Hills between the Dibang and Nao Dehing rivers in Arunachal Pradesh. We examined whether H. leuconedys occurs in India and its evolutionary relationships with other Hylobatidae species. We collected blood, tissue, and fecal samples from various populations of H. hoolock (N = 17) and the Mishmi Hills gibbons (N = 14) from their distribution in Northeast India, zoos, and rescues centers. We isolated DNA from these samples and constructed phylogenetic trees using partial D-loop and COI markers. We also performed whole mitochondrial analysis to study the phylogenetics of the Hylobatidae family. Our genetic analysis showed that none of the samples from India were H. leuconedys, and that all samples from the Mishmi Hills could be assigned to H. hoolock. Our mitogenome analysis supported this conclusion. We estimate that gibbon divergence from a common ancestor occurred 8.38 mya and that the split between H. hoolock and H. leuconedys occurred 1.49 mya. These findings will facilitate exchange of individuals from different zoos for captive breeding programs and conservation and management of wild populations of these gibbons.

Characterization of whole mitochondrial genome Amyda cartilaginea from Dharmasraya, West Sumatera

Previous data of the whole mitochondrial genome of soft-shelled turtle that it’s available in a public repository: Dogania subplana, Pelochelys cantorii, Chitra indica, Trionyx triunguis, Apalone spinifera, Rafetus swinhoei, and Pelodiscus sinensis. The first two species have natural distribution in Indonesia. Amyda cartilaginea is a species of soft-shelled turtle that is abundant in Indonesia. However, the whole mitochondrial genome data of A. cartilaginea is not available. This study aims to characterize the partial mitochondrial genome and analyze the phylogenetic position of A. cartilaginea. We reported almost complete mitochondrial genome of A. cartilaginea that caught from Batanghari river in Dharmasraya District, West Sumatera. The amplification of mitochondrial DNA fragments was performed using several primers designed following mitochondrial gene organization and sequence of D. subplana (Accession No AF366350). We sequenced half of the whole mitochondrial genome (7757 bp, 48%). The gene organization of the mitochondrial genome of A. cartilaginea was identic with D. subplana and P. cantorii. The phylogenetic tree analysis based on 16SrRNA revealed that the position of A. cartilaginea clustered with another soft-shelled turtle. Further study is needed to make a complete sequence of the mitochondrial genome of A. cartilaginea, with special focus on the control region to be applied to sustainable wild population management.

Genetic characterization of wild, broodstock and seed samples of Polititapes rhomboides (Bivalvia: Veneridae): Implications for hatchery seed production

The banded carpet shell Polititapes rhomboides is a fishery resource and a suitable candidate for the development of native clam aquaculture in Europe. Here, we analyzed nine microsatellite loci in wild samples to provide estimates of genetic diversity and population differentiation for NW Spain, the main production area of this clam. We also analyzed wild-caught broodstock and hatchery-reared seed to investigate the genetic consequences of seed production for stock enhancement purposes by mass spawning. We examined the seed sample as a whole (total seed), but also subdivided it into three size classes to assess the genetic consequences of size grading. While wild samples, broodstock included, displayed minimal or no genetic differences, the total seed showed a reduction in allelic richness (12–24 %) and a significant level of differentiation (FST = 0.026−0.043) with respect to wild samples. After performing parentage assignment, we detected a drastic reduction in the effective number of breeders (Ne) compared to the census number (85 %), and an inbreeding rate of 0.036 per generation. The low Ne and high inbreeding rate were mainly due to high variance in reproductive success. The seed size classes also showed a decrease in allelic richness and significant genetic differentiation, but we did not find significant differences in parental contribution to each size class. Our results may help the genetic-assisted management of wild populations, give insight into the genetic composition of the seed produced by mass spawning and provide a basis for the development of more effective hatchery practices and sustainable stock enhancement programs in P. rhomboides.

Identification of Priority Sites to Support Management of Commercially Important Sea Cucumber Species by Applying Infomap and Habitat Filters to Larval Dispersal Data

Stocks of commercially valuable sea cucumber species have declined in most tropical countries, which supply majority of the global demand. This work aimed to locate priority sites for the management ofHolothuria scabraandStichopus horrensin the western central Philippines. A passive larval dispersal model was run under four monsoonal regimes (Northeast monsoon, dry-transition, Southwest monsoon, and early Northeast monsoon), and the results subjected to theInfomapnetwork detection algorithm. Three clusters of closely related geographical nodes were identified [southeastern Palawan (Group I), western Panay and eastern Mindoro (Group II), and northern and western Palawan with western Mindoro (Group III)]. Remotely sensed habitat data were used to parameterize the degree of connectivity observed among sites (H. scabraspawning and settlement requires the presence of seagrass and mangrove, whileS. horrensrequires corals and seagrass). Local retention, self-recruitment, settlement success and sink diversity were then calculated for each node with suitable habitat. The locations were ranked according to each metric and those with higher larval export rates, a higher diversity of larval sources and a high degree of successful larval contribution to other sites were deemed crucial for the management of wild populations. Sixteen high-priority sites were identified, distributed mainly along northern Palawan and western Panay. Six sites were common for both species at different seasons, and no single location fulfilled all stated criteria across the four seasons and both sea cucumber species considered. The priority sites for management could serve as broodstock selection and juvenile restocking areas for aquaculture production clusters, which when properly implemented, could lead to an increase in sea cucumber production and contribute to natural populations. On a broader scale, the designation of closely related clusters and incorporation of habitat requirements to dispersal data provided critical input for the delineation of ecologically meaningful management units for sea cucumbers within the region.

A non-lethal method for detection of Bonamia ostreae in flat oyster (Ostrea edulis) using environmental DNA

Surveillance and diagnosis of parasitic Bonamia ostreae infections in flat oysters (Ostrea edulis) are prerequisites for protection and management of wild populations. In addition, reliable and non-lethal detection methods are required for selection of healthy brood oysters in aquaculture productions. Here we present a non-lethal diagnostic technique based on environmental DNA (eDNA) from water samples and demonstrate applications in laboratory trials. Forty oysters originating from Limfjorden, Denmark were kept in 30 ppt sea water in individual tanks. Water was sampled 6 days later, after which all oysters were euthanized and examined for infection, applying PCR. Four oysters (10%) were found to be infected with B. ostreae in gill and mantle tissue. eDNA purified from the water surrounding these oysters contained parasite DNA. A subsequent sampling from the field encompassed 20 oysters and 15 water samples from 5 different locations. Only one oyster turned out positive and all water samples proved negative for B. ostreae eDNA. With this new method B. ostreae may be detected by only sampling water from the environment of isolated oysters or isolated oyster populations. This non-lethal diagnostic eDNA method could have potential for future surveys and oyster breeding programs aiming at producing disease-free oysters.