Main Species Groups Research Articles

Plasticity and overlap of trophic niches in tropical breeding Laridae

Trophic ecology of seabirds in tropical regions remains poorly understood despite the large number of multispecies breeding colonies supported by these ecosystems. Here, we used the isotopic niche (δ15N and δ13C) of 5 Laridae species at 2 breeding areas in Cuba to analyze the plasticity and interspecific overlap of trophic niche determined from chick down and feather samples. The down samples reflected the female trophic regime before laying, while the feather samples incorporated the trophic regime of the chicks provided by the parents during rearing. Two main species groups were identified by their isotopic niche characteristics: species with small and quite stable isotopic niches (trophic specialists) and species with large and highly variable isotopic niches (trophic generalists). Laughing gull Leucophaeus atricilla, royal tern Thalasseus maximus, and sandwich tern T. sandvicensis were the generalists and showed significant isotopic niche differences between breeding areas and phases. Bridled tern Onychoprion anaethetus and roseate tern Sterna dougallii were trophic specialists, but only the former exhibited significant variations in isotopic niche breadth between breeding phases. Overall, trophic (inferred from isotopic) niche overlap was relatively low, suggesting that these tropical seabirds reduce competition through niche partitioning. We concluded that trophic niche plasticity and segregation appear to constitute an important adaptive strategy to ensure the breeding success of sympatrically breeding Laridae in north-central Cuba.

Forest Area and Structural Variable Estimation in Boreal Forest Using Suomi NPP VIIRS Data and a Sample from VHR Imagery

Our objective was to develop a method for the assessment of forest area and structural variables for cases in which the availability of representative ground reference data is poor and these data are not collected from the whole area of interest. We implemented two independent approaches to the estimation of the forest variables of a European boreal forest: (i) the computation of wall-to-wall estimates using moderate- to low-resolution VIIRS imagery from the Suomi NPP mission; and (ii) the visual interpretation of plots of samples from very high resolution (VHR) satellite data obtained via a two-stage design. Our focus was on the statistical comparison of forest resources at a country or larger level. The study area was boreal forest ranging from Norway to the Ural Mountains in Russia. We computed a seamless mosaic from 111 VIIRS images. From the mosaic, we computed predictions for the forest area, growing stock volume, height of the dominating tree layer, proportion of conifers and broadleaved trees, site fertility class, and leaf area index. The reference data for the VIIRS imagery were national forest inventory (NFI)-based raster maps from Finland. The first stage sample of VHR data included 42 images; of these, a second stage sample of 2690 plots was visually interpreted for the same variables. The forest area prediction from VIIRS for the whole study area was 1.2% higher than the VHR-based result. All other structural variable predictions using VIIRS fitted within the 95% confidence intervals computed from the VHR sample except for estimates of the main tree species groups, which were outside the limits. A comparison of VIIRS-based forest area estimates using Finnish and Swedish NFI data indicated overestimations of 10.0% points and 4.6% points, whereas the total growing stock volumes were overestimated by 8% and underestimated by 3.4%, respectively. The correlation coefficients between the VIIRS and VHR image predictions at the 42 VHR image locations varied from 0.70 to 0.85. The VIIRS maps strongly averaged the local predictions due to their coarse spatial resolutions. Based on our findings, the approach using two independent estimations yielded similar figures for the central forest variables for the European boreal forest. A model computed using reference data from a small part of the area of interest can provide satisfactory predictions for a much larger area with a similar biome. Therefore, our concept is applicable to the estimation and overall mapping of a forest area and central structural variables at regional to national levels.

Genomic variation in the genus Beta based on 656 sequenced beet genomes

Cultivated beets (Beta vulgaris ssp. vulgaris) constitute important crop plants, in particular sugar beet as an indispensable source of sucrose. Several species of wild beets of the genus Beta with distribution along the European Atlantic coast, Macaronesia, and throughout the Mediterranean area exist. Thorough characterization of beet genomes is required for straightforward access to genes promoting genetic resistance against biotic and abiotic stress. Analysing short-read data of 656 sequenced beet genomes, we identified 10 million variant positions in comparison to the sugar beet reference genome RefBeet-1.2. The main groups of species and subspecies were distinguishable based on shared variation, and the separation of sea beets (Beta vulgaris ssp. maritima) into a Mediterranean and an Atlantic subgroup as suggested by previous studies could be confirmed. Complementary approaches of variant-based clustering were employed based on PCA, genotype likelihoods, tree calculations, and admixture analysis. Outliers suggested the occurrence of inter(sub)specific hybridisation, independently confirmed by different analyses. Screens for regions under artificial selection in the sugar beet genome identified 15 Mbp of the genome as variation-poor, enriched for genes involved in shoot system development, stress response, and carbohydrate metabolism. The resources presented herein will be valuable for crop improvement and wild species monitoring and conservation efforts, and for studies on beet genealogy, population structure and population dynamics. Our study provides a wealth of data for in-depth analyses of further aspects of the beet genome towards a thorough understanding of the biology of this important complex of a crop species and its wild relatives.

Tracking Adaptive Pathways of Invasive Insects: Novel Insight from Genomics.

Despite the huge human and economic costs of invasive insects, which are the main group of invasive species, their environmental impacts through various mechanisms remain inadequately explained in databases and much of the invasion biology literature. High-throughput sequencing technology, especially whole-genome sequencing, has been used as a powerful method to study the mechanisms through which insects achieve invasion. In this study, we reviewed whole-genome sequencing-based advances in revealing several important invasion mechanisms of invasive insects, including (1) the rapid genetic variation and evolution of invasive populations, (2) invasion history and dispersal paths, (3) rapid adaptation to different host plant ranges, (4) strong environmental adaptation, (5) the development of insecticide resistance, and (6) the synergistic damage caused by invasive insects and endosymbiotic bacteria. We also discussed prevention and control technologies based on whole-genome sequencing and their prospects.

Assembly rules vary seasonally in stable phytoplankton associations of the Gulf of Naples (Mediterranean Sea)

AbstractCoastal phytoplankton present remarkable variability because of complex patterns and relationships of hydrological parameters at the land–sea interface. We analysed a time series of 917 phytoplankton samples collected in the period 1984–2010 at the coastal station LTER‐MC (Gulf of Naples, Mediterranean Sea) with the aims of determining: (i) whether recurrent species associations are recognizable in this variable coastal environment; (ii) what are their composition and seasonal patterns; (iii) what are the environmental variables driving their distributions, and (iv) to what extent those associations are functionally homogeneous. Using a cluster analysis of a dataset of the 87 more frequent and abundant species in the samples, we identified seven main groups of species. Five of them were recurrent over the years in the same seasons, while two other groups showed a bimodal occurrence or no clear seasonality, respectively. Differences in the occurrence of those assemblages were primarily associated with the season (i.e., temperature), and the coastal nature of the site (mainly salinity). Except for the winter cluster, which included mostly coccolithophores and silicoflagellates, diatoms were present in all associations, along with species belonging to diverse phylogenetic groups. The diversity of morphological features defining ecological traits varied across the different associations, with a maximum divergence in the spring association and a minimum in winter. We conclude that the stability of the associations is related to the marked phenological recurrence of their individual species and their overlap in specific periods of the year, while convergent or divergent trait compositions in the different associations indicate a variable strength of the environmental filtering across the seasonal succession.

Diversity and function of soil macrofauna: key information for studying the sustainability of tropical social-ecological systems

The biological diversity is a natural inherent element of social-ecological systems. Within the great species diversity there is a group of small invertebrates (2–20 mm), inhabiting terrestrial soils and aquatic sediments, known as macrofauna. Contrary to its name indicates, the macrofauna is generally overlooked, poorly represented in biological inventories or management programs, and not contemplated in any political agenda, but they consist of high number and many groups of species with a high diversity in shapes and functions. Knowing this diversity and their functions in both terrestrial and aquatic habitats is fundamental to understand its role within the social-ecological systems, by giving key information that would advance our comprehension on the role of macrofauna in the quality of environmental services provided by ecosystems. Furthermore, this understanding is crucial due to the fact that the macrofauna is threatened by anthropogenic activities, which could lead to local modifications in the processes that take place in the soil. Therefore, the purpose of this work is, in general, to make known to the reader the main species groups that integrate the macrofauna, the equivalent functional role that these organisms play in the terrestrial and aquatic habitats where they occur, as well as their importance in studies of sustainability in tropical social-ecological systems. Keywords: Biodiversity, benthic macrofauna, edaphic macrofauna, functional traits, ecosystems.

Short-term effects of hardened wood ash and nitrogen fertilisation on understory vegetation in a Norway spruce forest in south-east Norway

ABSTRACT In a fertiliser experiment in a Norway spruce forest in SE Norway, four treatments were applied in a block design with three replicates per treatment. Treatments included 3 t wood ash ha−1 (Ash), 150 kg nitrogen ha−1 (N), wood ash and nitrogen combined (Ash + N), and unfertilised control (Ctrl). Treatment effects on understory plant species numbers, single abundances of species and (summarised) cover of main species groups were studied. Two years after treatment there were no significant changes for species numbers or abundances of woody species, dwarf shrubs or pteridophytes, nor for Sphagnum spp. in the bottom layer. The cover of graminoids decreased in Ctrl plots. Herb cover increased significantly in Ash + N and N plots due to the increase of Melampyrum sylvaticum. In Ash + N plots, mosses decreased significantly in species number, while their cover increased. Moss cover also decreased significantly in N plots. The species number and cover of hepatics decreased significantly in Ash and Ash + N plots. Hepatics cover also decreased in Ctrl plots. Both the lichen number and cover decreased in Ash + N plots. Single species abundances decreased for many bryophytes in fertilised plots. To conclude, fertilisation had modest effects on vascular plants, while bryophytes were more strongly affected, especially by Ash + N.

Molecular taxonomic identification and species-level phylogeny of the narrow-mouthed frogs of the genus Rhombophryne (Anura: Microhylidae: Cophylinae) from Madagascar

The study of diamond frogs (genus Rhombophryne, endemic to Madagascar) has been historically hampered by the paucity of available specimens, because of their low detectability in the field. Over the last 10 years, 13 new taxa have been described, and 20 named species are currently recognized. Nevertheless, undescribed diversity within the genus is probably large, calling for a revision of the taxonomic identification of published records and an update of the known distribution of each lineage. Here we generate DNA sequences of the mitochondrial 16S rRNA gene of all specimens available to us, revise the genetic data from public databases, and report all deeply divergent mitochondrial lineages of Rhombophryne identifiable from these data. We also generate a multi-locus dataset (including five mitochondrial and eight nuclear markers; 9844 bp) to infer a species-level phylogenetic hypothesis for the diversification of this genus and revise the distribution of each lineage. We recognize a total of 10 candidate species, two of which are identified here for the first time. The genus Rhombophryne is here proposed to be divided into six main species groups, and phylogenetic relationships among some of them are not fully resolved. These frogs are primarily distributed in northern Madagascar, and most species are known from only few localities. A previous record of this genus from the Tsingy de Bemaraha (western Madagascar) is interpreted as probably due to a mislabelling and should not be considered further unless confirmed by new data. By generating this phylogenetic hypothesis and providing an updated distribution of each lineage, our findings will facilitate future species descriptions, pave the way for evolutionary studies, and provide valuable information for the urgent conservation of diamond frogs.

Stand-level growth models for long-term projections of the main species groups in Norway

ABSTRACT Stand-level growth and yield models are important tools that support forest managers and policymakers. We used recent data from the Norwegian National Forest Inventory to develop stand-level models, with components for dominant height, survival (number of survived trees), ingrowth (number of recruited trees), basal area, and total volume, that can predict long-term stand dynamics (i.e. 150 years) for the main species in Norway, namely Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.), and birch (Betula pubescens Ehrh. and Betula pendula Roth). The data used represent the structurally heterogeneous forests found throughout Norway with a wide range of ages, tree size mixtures, and management intensities. This represents an important alternative to the use of dedicated and closely monitored long-term experiments established in single species even-aged forests for the purpose of building these stand-level models. Model examination by means of various fit statistics indicated that the models were unbiased, performed well within the data range and extrapolated to biologically plausible patterns. The proposed models have great potential to form the foundation for more sophisticated models, in which the influence of other factors such as natural disturbances, stand structure including species mixtures, and management practices can be included.

Rosaceae, Brassicaceae and pollen beetles: exploring relationships and evolution in an anthophilous beetle lineage (Nitidulidae, Meligethes-complex of genera) using an integrative approach

BackgroundMeligethes are pollen-beetles associated with flowers of Rosaceae as larvae. This genus currently consists of 63 known species in two subgenera, Meligethes and Odonthogethes, predominantly occurring in the eastern Palaearctic. We analyzed 74 morphological and ecological characters (169 states) of all species, as well as of 11 outgroup species from 7 Meligethinae genera (including Brassicogethes), to investigate their phylogeny. We also conducted a parallel molecular analysis on 9 Meligethes, 9 Odonthogethes, 3 Brassicogethes and 2 Meligethinus species based on DNA sequence data from mitochondrial (COI, 16S) and nuclear (CAD) genes.ResultsMorphological phylogenetic reconstructions supported the monophyly of the whole genus and clades corresponding to purported subgenera Meligethes s.str. and Odonthogethes. Main species-groups were mostly confirmed, however some unresolved polytomies remained. Molecular data placed members of Brassicogethes (including 42 mostly W Palearctic species associated with Brassicaceae) as sister to Odonthogethes, with this clade being sister to Meligethes s.str. This phylogenetic scenario suggests that monophyletic Meligethes s.str., Odonthogethes and Brassicogethes should be regarded alternatively as three subgenera of a monophyletic Meligethes, or three genera in a monophyletic genus-complex, with mutually monophyletic Brassicogethes and Odonthogethes. Molecular analyses estimated the origin of this lineage at ca. 14–15 Mya from a common stem including Meligethinus.ConclusionsWe hypothesize that the ancestor of Meligethes specialized on Rosaceae in the Middle Miocene (likely in Langhian Age) and subsequently radiated during Late Miocene and Plio-Pleistocene maintaining a trophic niche on this plant family. This radiation was primarily due to geographic isolation in E Asiatic mountain systems. Combined evidence from morphology, ancestral state parsimony reconstruction of host-plant associations and molecular evidence suggested that Rosoideae (Rosa spp.) represented the ancestral hosts of Meligethes s.str., followed by an independent shift of ancestral Odonthogethes (ca. 9–15 Mya) on Rubus (Rosoideae) and members of Rosaceae Spiraeoideae. Other ancestral Odonthogethes probably shifted again on the unrelated plant family Brassicaceae (maybe 8–14 Mya in S China), allowing a rapid westward radiation of the Brassicogethes clade.

The New Hyperspectral Satellite PRISMA: Imagery for Forest Types Discrimination.

Different forest types based on different tree species composition may have similar spectral signatures if observed with traditional multispectral satellite sensors. Hyperspectral imagery, with a more continuous representation of their spectral behavior may instead be used for their classification. The new hyperspectral Precursore IperSpettrale della Missione Applicativa (PRISMA) sensor, developed by the Italian Space Agency, is able to capture images in a continuum of 240 spectral bands ranging between 400 and 2500 nm, with a spectral resolution smaller than 12 nm. The new sensor can be employed for a large number of remote sensing applications, including forest types discrimination. In this study, we compared the capabilities of the new PRISMA sensor against the well-known Sentinel-2 Multi-Spectral Instrument (MSI) in recognition of different forest types through a pairwise separability analysis carried out in two study areas in Italy, using two different nomenclature systems and four separability metrics. The PRISMA hyperspectral sensor, compared to Sentinel-2 MSI, allowed for a better discrimination in all forest types, increasing the performance when the complexity of the nomenclature system also increased. PRISMA achieved an average improvement of 40% for the discrimination between two forest categories (coniferous vs. broadleaves) and of 102% in the discrimination between five forest types based on main tree species groups.

Genetic Diversity and Similarity of Asian and European Pears (Pyrus Spp.) Revealed by Genome Size and Morphological Traits Prediction

ABSTRACT Pears (Pyrus spp.) mainly are divided into two main groups of Asian and European species with a wide diversity or similarity in fruit and morphological traits. In this study, flow cytometry was performed to evaluate the genome size of 37 cultivars and genotypes of Asian, European, and Iranian indigenous pears. Besides, the relationship between cytological and morphological traits was investigated for the first time. Morphological traits were measured based on the International Union for the Protection of New Varieties of Plants (UPOV) descriptor. There were positive relationships between genome size, the fruit pedicel length, and the length to fruit diameter ratio. Although, as the genome size was increased, the fruit diameter and size were decreased. Increasing 1.6 pg of the genome size causes a reduction of one cm in the pear fruit diameter. Moreover, with a larger genome size by 1.1 pg, there was an increase in fruit pedicel by one cm. The obtained results revealed that most of the Iranian native genotypes were similar in shape to European pears, but some of them were also oriented to Asian pear cultivars. Most studied cultivars originated between different regions were diploid (2n = 34) and their genome size varied between 0.99 and 1.99 pg. The average genome size of European and Iranian pears was 1.29 pg and Asian’s was 1.32 pg. The principal component analysis (PCA) result showed that the Asian and European genotypes were distinctly separated. Also, according to the cluster analysis, the indigenous cultivars of Iran can be located in the European pear group species. There was a relationship between the East Asian and European pear origins because of the possible gene flow between two major pear culture regions in the past. In general, Iran can be considered as an important region and pathway of gene flow transfer and a rich center of genetic variation of pears. Therefore, this study provided essential information and a useful tool for genetic diversity or similarity assessment of pears through genome size and some morphological traits prediction. Further research on wider fruit tree species in the different fruit-growing regions of the world will warrant the use of genome size as a novel prediction tool for the important morphological traits with specific commercial breeding objectives.

Large scale mapping of forest attributes using heterogeneous sets of airborne laser scanning and National Forest Inventory data

BackgroundThe Norwegian forest resource map (SR16) maps forest attributes by combining national forest inventory (NFI), airborne laser scanning (ALS) and other remotely sensed data. While the ALS data were acquired over a time interval of 10 years using various sensors and settings, the NFI data are continuously collected. Aims of this study were to analyze the effects of stratification on models linking remotely sensed and field data, and assess the accuracy overall and at the ALS project level.Materials and methodsThe model dataset consisted of 9203 NFI field plots and data from 367 ALS projects, covering 17 Mha and 2/3 of the productive forest in Norway. Mixed-effects regression models were used to account for differences among ALS projects. Two types of stratification were used to fit models: 1) stratification by the three main tree species groups spruce, pine and deciduous resulted in species-specific models that can utilize a satellite-based species map for improving predictions, and 2) stratification by species and maturity class resulted in stratum-specific models that can be used in forest management inventories where each stand regularly is visually stratified accordingly. Stratified models were compared to general models that were fit without stratifying the data.ResultsThe species-specific models had relative root-mean-squared errors (RMSEs) of 35%, 34%, 31%, and 12% for volume, aboveground biomass, basal area, and Lorey’s height, respectively. These RMSEs were 2–7 percentage points (pp) smaller than those of general models. When validating using predicted species, RMSEs were 0–4 pp. smaller than those of general models. Models stratified by main species and maturity class further improved RMSEs compared to species-specific models by up to 1.8 pp. Using mixed-effects models over ordinary least squares models resulted in a decrease of RMSE for timber volume of 1.0–3.9 pp., depending on the main tree species. RMSEs for timber volume ranged between 19%–59% among individual ALS projects.ConclusionsThe stratification by tree species considerably improved models of forest structural variables. A further stratification by maturity class improved these models only moderately. The accuracy of the models utilized in SR16 were within the range reported from other ALS-based forest inventories, but local variations are apparent.

Five new clavate-stigma Waltheria species endemic to Brazilian Cerrado (Malvaceae s. l., Byttnerioideae, Hermannieae)

Five new species are described and illustrated: Waltheria hatschbachii, W. hoehnei, both endangered for extinction, W. coriacea, W. flavovirens and W. matogrossensis. All are endemic to Brazil, in Cerrado s. l. associated with the Brazilian Plateau in N, NE, CW, and SE Brazil. Their affinities and the distinctness from W. ferruginea s. l. are discussed, and they are associated and compared with W. ferruginea s. str., from cerrado, W. brachypetala, from caatinga, W. biribiriensis and W. terminans, both from campo rupestre. The geographic distribution of all nine species is illustrated, and a new identification key for these and for the two sections of Waltheria is provided. All nine species share a clavate stigma in pin (or thrum) flowers, that morphotype given earlier as distinguishing one of three main species groups of the genus, and a new character, the ferruginea type stipitate-stellate trichome, illustrated here. Subconduplicate petals are first reported in the tribe Hermannieae, often keyed by flat petals. Waltheria is first signaled here to present the same enigmatic biogeographical pattern noted before for Triraphis (Poaceae) between Chapada dos Veadeiros, Africa and Australia. Other new taxonomic characters for Waltheria are given.

The influence of environmental factors on the distribution and composition of plant species in Oued Charef dam, northeast of Algeria

Abstract. Moualki N, Boukrouma N. 2021. The influence of environmental factors on the distribution and composition of plant species in Oued Charef dam, North East of Algeria. Biodiversitas 22: 346-353. Identification of the primary factors that influence the ecological distribution of species groups is important to managers of Oued Charef dam in northern Algeria. This study aimed to identify main ecological species groups, describe the site conditions associated with these species groups, and the relationships between environmental factors and the distribution of ecological species groups using Ward’s cluster analysis for classification and principal component analysis (PCA). For this purpose, 50 plots (200 m2 each) were sampled using the Braun- Blanquet method. Soil samples were collected and analyzed to study soil properties. Multivariate analysis methods were used to classify and determine the relationship between species composition and environmental factors and to recognize ecological species groups. The R i386 (version 4.0.3) software was used for data analyzing. Ward's cluster analysis when applied on terrestrial species data gives three groups distinctly distributed on ordination plan. In cluster groups of terrestrial species Group (1) is dominated by Daisies chrysanthemum, Group (2) by Cynodon dactylon L, and Group (3) dominated by Fumana thymifolia. The groups of terrestrial species are readily superimposed on PCA ordination plane. The most important environmental factors associated with terrestrial species composition in Oued Charef dam communities were conductivity (EC), FSA, FSI, clay, salinity, phosphorus (PO4), TN (nitrogen), nitrates (NO3), and nitrites (NO2). While among the edaphic factors only pH showed a negative correlation to plant species this may due to the anthropogenic disturbances however further studies are needed to explore the rest of parts of the said regions. This study gives important insights on ecological relationships between plant biodiversity and soil chemical in a primary wetland ecosystem in northeast of Algeria.

Molecular Phylogeny of the Notomicrine Water Beetles (Coleoptera: Noteridae) Reveals Signatures of Gondwanan Vicariance and Ecological Plasticity

AbstractNotomicrinae (Coleoptera: Noteridae) is a subfamily of minute and ecologically diverse aquatic beetles distributed across the Southeast Asia, Oceania, and the Americas. We investigate the evolution of Notomicrinae and construct the first species-level phylogeny within Noteridae using five nuclear and mitochondrial gene fragments. We focus on the genus Notomicrus Sharp (Coleoptera: Noteridae), sampling 13 of the 17 known Notomicrus species and an additional 11 putative undescribed species. We also include Phreatodytes haibaraensis Uéno (Coleoptera: Noteridae). Datasets are analyzed in Maximum Likelihood and Bayesian frameworks. With these, we 1) estimate divergence times among notomicrine taxa and reconstruct the biogeographical history of the group, particularly testing the hypothesis of Gondwanan vicariance between Old World and New World Notomicrus; 2) additionally, we assess ecological plasticity within Notomicrinae in the context of the phylogeny; and 3) finally, we test the monophyly of tentative species groups within Notomicrus and place putative new taxa. We recover a monophyletic Notomicrinae, with Phreatodytes sister to Notomicrus. We estimate the crown age of Notomicrinae to be ca. 110 Mya. The crown age of Notomicrus is recovered as ca. 75 Mya, there diverging into reciprocally monophyletic Old and New World clades, suggesting Gondwanan vicariance. Our phylogenetic estimate indicates a strong degree of ecological plasticity within Notomicrinae, with habitat switching occurring in recently diverging taxa. Finally, we recover five main species groups in Notomicrus, one Old World, Four New World, with tentative affirmation of the placement of undescribed species.

Spring dynamics of cyprinids parasitofauna under pond aquaculture conditions in the Astrakhan region

The results of spring monitoring of invasive diseases of Cyprinids in fish farms of the Astrakhan region are presented. Indicator representatives of the main species groups of the ectoparasite fauna of Cyprinids (monogenetic trematodes, fish leeches, crustaceans and unicellular skin parasites) are considered, and the quantitative dynamics of invasions in spring season under aquaculture conditions in the Astrakhan region are considered. In the period from April to May 2020, 170 samples of carp fish of five species were examined: carp, bream, roach, silver bream, rudd. The study was carried out by the parasitological method on live fish, the intensity of invasion was determined. The causative agents of the following invasive diseases of cyprinids were identified: dactylogyrosis, argulez, trichodinosis, diplozoonosis, piscicolez. For all detected parasites, a low intensity of invasion was noted (1–20 ind. per fish), which corresponds to the baseline values for pond rearing of Cyprinids and allows us to speak about satisfactory conditions for fish. The number of leeches averaged 10 specimens per fish, which is rather high in spring and indicates inadequate preparation of ponds for the fish-breeding season, or early arrival of spring; however, according to quantitative criteria, this corresponds to a low intensity of invasion. In general, the results obtained are consistent with the background presence of ectoparasites on cyprinids during pond rearing and allow us to speak about satisfactory conditions for keeping fish in the commercial farms of the Astrakhan region. The effect of earlier periods of the onset of high water temperatures in the river and ponds in recent years (2019–2020) on the development of the dynamics of invasive diseases in fish farms of the Astrakhan region requires additional study

Suckermouth-armored Catfish (Siluriformes: Loricariidae) of Central and Southern Vietnam

Presently, invasive fish species become dominant in some freshwater waterbodies and watercourses of Central and South Vietnam in terms of abundance, successfully competing with native species for ecological niches and environmental resources. This can ultimately reduce the diversity of native fish communities and cause their further transformation. Loricariids are considered the main group of invasive fish species being a serious threat to tropical and subtropical freshwater ecosystems. In this regard, the distribution and morphology of suckermouth-armored catfishes (Pterygoplichthys spp.) in different habitats of Central and South Vietnam were studied. A total of 54 reservoirs belonging to the basins of 15 large and small rivers were surveyed. Specimens were examined for 7 meristic and 34 plastic characters. The osteological analysis of the axial skeleton of fish conducted using radiography. Morphological differences and a number of developmental anomalies of morphology were found in different armored catfish populations from Vietnamese waters. It is noted that deliberate or accidental introduction of suckermouth-armored catfishes and their further spread can have negative consequences for the biodiversity of Vietnam’s aquatic ecosystems.

Arms as areas for larval development of migratory fish species in a Neotropical reservoir and the influence of rainfall over abundances.

The aim of the present study was to verify the use of the arms of the Itaipu Reservoir as areas of initial development for migratory fish species and to assess the relationship between rainfall and the spawning of migratory fish. Accordingly, fish larvae were collected from five arms of the reservoir from 2009 to 2016 using 0.5 mm plankton nets. Density was standardized as the number of larvae per 10 m3 filtered water, and the captured larval and juvenile specimens were identified at the lowest-possible taxonomic level. The larvae were also classified according to the degree of development and notochord flexion stage: larval vitelline, pre-flexion, flexion and post-flexion. To evaluate the distribution of larval abundance and the developmental stage along the longitudinal gradients of the arms, the data were evaluated using a set of nested linear models, following the AIC and Bayesian information criteria. In addition, an analysis of covariance was performed to investigate the influence of rainfall on the larval abundance of migratory species. During sampling, several species of economic and conservation interest such as Salminus brasiliensis and Pseudoplatystoma corruscans were collected. The larvae of the migratory fish taxa were captured from all sampled arms, which indicate them as areas of initial development. Nevertheless, it was observed that larval density increases from fluvial towards lacustrine zones inside the arms. Also, the present study verified that species, even in lentic environments, respond positively to rainfall stimuli in a manner similar to that exhibited by conspecifics in lotic environments. Such results reinforce the necessity of the protection of arms aiming at the conservation of this main group of species impaired by the construction of dams.

Optimising harvest strategies over multiple objectives and stakeholder preferences

Natural resource management has long recognised that the multi-objective nature of management is important, but has struggled to operationalise this into quantitative, measurable objectives for functional use in management. Operationalising broader ecological and social objectives has been particularly problematic. In fisheries management, the focus has mainly been on target species sustainability and, in the past few decades, on profitability. However, multi-objective management is now essential as fisheries have become recognised as complex social-ecological-systems.Policy and legislation demand a move towards quantitative approaches for reconciling multiple objectives and operationalising these within harvest strategies. We present a quantitative, non-commensurable-unit approach, via a multi-indicator value function with explicit objective preference weights. We use a simulation to set Total Allowable Catches (TACs) for three main species groups in a reef line fishery in Australia's Great Barrier Reef. Our method enables stakeholders to consider a richer range of tradeoffs than is possible with bio-economic models. Moreover, it allows the formal evaluation of performance across alternative stakeholder group preferences, providing an impartial way to obtain an overall optimum TAC. The simulation requires extensive fishery data and requires the performance indicators associated with each objective to be quantitatively and defensibly defined. Thus, our approach provides a pathway forward that forces managers and stakeholders to confront the associated data requirements.