Biotic Characteristics Research Articles

Long-Term Changes in the Thermal and Ice Regime of the Biebrza River (Northeastern Poland) in the Era of Global Warming

In the context of ongoing environmental changes, particularly against the backdrop of global warming, significant attention is being given to areas of exceptional natural value that, in many aspects, retain a pristine character. One such area is the Biebrza River in northeastern Poland, which, together with the wetlands in its basin, forms one of the most valuable ecosystems of its kind in Europe. This study analyses the changes in the thermal and ice regime for two hydrological stations, Sztabin and Burzyn, in the period from 1959 to 2023. It was found that the average annual water temperature in this period for the Biebrza River increased by 0.28 °C/decade, and in the case of ice phenomena, statistically significant changes for both stations showed a decline, with an acceleration of the ice cover disappearance by an average of 3 days/decade. These recorded changes should be considered unfavourable, as they will affect the transformation of both the biotic and abiotic characteristics of the river itself, as well as the natural elements associated with it.

Factors and effects of inter-individual variability in silver birch phenology using dense LiDAR time-series

Comprehending and quantifying local variability in plant phenology, alongside its impacts on tree growth, is challenging due to spatially and temporally heterogeneous environmental factors that interact to affect phenological events and periods. Although previous studies have focused on the climatic factors driving phenological events at the stand level, the influences of competition, neighborhood characteristics, species richness, and water availability on plant phenology remain unclear. In the present paper, we used hourly terrestrial LiDAR surveys performed between April 2020 and April 2021 to investigate the influence of local factors (neighborhood and topography) on the phenology of silver birch trees (Betula pendula Roth.). We also examined how phenological events affect growth in tree height and crown area. All response and explanatory variables were estimated using LiDAR time-series data and a field survey campaign. Our findings demonstrate a high within-species variability in plant phenology that is controlled by biotic and abiotic characteristics of the ecosystem. We found that between tree variation in leaf burst, completion of the leaf growth and length of canopy growth period were affected by tree size, neighborhood species richness, level of suppression and competition, which potentially indicate plant responses to light availability. The beginning of senescence, completion of leaf drop, and length of autumn phenology were mostly affected by topographic water index, which reflects water availability and can be linked to nutrient availability and exposure to wind. Furthermore, we demonstrated that an earlier leaf burst, and delayed beginning of senescence were associated with larger absolute growth in canopy area but found no clear relationship between height growth and phenology. Our study highlights the capability of dense, high-quality LiDAR time-series to detect significant phenological variation among individuals of the same species within the same locality, demonstrating the potential of LiDAR time-series as a tool for understanding phenology and its impacts.

Coastal dune management affects above and belowground biotic characteristics.

Dune vegetation mediates dune-building through trapping wind-blown sand and reduces dune erosion by attenuating wave energy via above- and belowground biomass. Despite the role of vegetation in dune functions, the amount and distribution of biomass within a dune remains poorly quantified due to a lack of ample data. Our objectives were to determine the effects of management history and elevation on (1) dune belowground biotic structure and aboveground community composition and (2) to determine best predictors of belowground biomass. We sampled belowground biomass and sedimentology across the dune profile at sites in the Outer Banks, North Carolina, USA. Dunes were classified as either unmanaged (no anthropogenic interventions) or managed (sand fencing, vegetation planting, dune construction). Living belowground biomass was higher in unmanaged dunes and decreased with depth. Non-living belowground biomass was 50% higher than living biomass and with greater abundance in unmanaged dunes. Elevation was a significant covariate of living and non-living belowground biomass, vegetative cover and species richness. Plant community composition varied less in managed dunes and differed significantly from unmanaged dunes. Vegetative cover, species richness, elevation, sedimentology and management history were predictors of belowground biomass. These results underscore the influence of management and geomorphology on dune plant communities, which may influence erosion resistance.

Sub-habitat classification of temperate salt marshes in Japan based on aquatic fauna

Salt marshes are being lost worldwide even though they provide essential ecosystem services. Habitat classification of salt marshes based on fauna, which is an effective indicator of their ecosystems, is expected to be useful to effectively assess the baseline for conservation and restoration; however, it has not been well studied. This study aimed to identify the diversity of salt marsh sub-habitats for fauna, where biota was collected and the physicochemical environments were measured in 101 small patches of salt marsh (i.e., survey sites) across 32 temperate tidal rivers and inlets in Fukuoka Prefecture, Kyushu, Japan. A total of 78 aquatic animal species (decapod crustaceans, gastropod mollusks, bivalves, nereidid polychaetes, and fish) were observed, 63 of which were used as indicators for sub-habitat identification. Although reed plants covered 90 of the 101 survey sites, the survey sites were classified into six clusters based on fauna. Representative aquatic animals were identified in each cluster, and these six clusters had different physicochemical environments, such as salinity and sediment conditions. The results indicated that the six sub-habitats had different biotic and abiotic characteristics. On the other hand, the results of the ordination analysis indicated that the fauna of the six sub-habitats do not occur independently of each other but are composed of continuous and gradually changing fauna along environmental gradients. Although no significant differences in the areas of salt marsh patches among the clusters, species richness differed significantly, suggesting that physicochemical environments, such as salinity and sediment conditions, rather than spatial factors, may affect species diversity. The findings emphasize that each sub-habitat supports species diversity in temperate salt marshes and are expected to contribute to planning targets for future salt marsh conservation/restoration and further improvements in artificial marshes.

Living on the edge: identifying demographic bottlenecks in an isolated sage‐grouse population

The greater sage‐grouse (Centrocercus urophasianus: hereafter sage‐grouse) population in Modoc County California is geographically isolated and contains a single lek (from 56 leks in the 1940s), despite significant efforts to increase the population through translocations and habitat improvement. Repeated wildfire within the landscape has led to an increase in invasive annual grasses and a decrease in sagebrush (Artemisia sp.) cover in important nesting and brood‐rearing habitat. We estimated survival for adult females, nests, and chicks and assessed biotic characteristics that may influence these survival estimates to identify factors that may be limiting population growth. We monitored 37 female sage‐grouse marked with GPS PTTS, 39 nests, and 8 broods for 3 years (2019–2021). We measured vegetation characteristics for nests at the microsite and landscape scale to evaluate effects on daily nest survival (DNS). We used survival rates from all life stages to parameterize matrix models and estimate population growth rate. Mean nest success over 3 years was 29% (95% CI: 17.1–44.8) across a 29‐day incubation period and DNS declined as the proportion of both medusahead Taeniatherum caput‐medusae and Japanese brome Bromus japonicus around the nest increased. Across all three years, mean chick survival across a 54‐day period was 44% (95% CI: 0.9–72.3) and mean annual survival for adult females was 29% (95% CI: 17.8–43.7). Our estimated vital rates were 45–55% lower than distribution‐wide estimates and the projected population growth rate was strongly declining (0.411, 95% CI: 0.30–0.52). Our results suggested recent cover changes associated with wildfire on the study area may have had a detrimental effect on this population across all life stages, and if attention is not given to preventing the transition from sagebrush communities into invasive grasslands, this population and others in degraded landscapes may not persist.

Benthic modification and biotic associations at natural and artificial habitats excavated by Epinephelus morio and Lutjanus campechanus

Pockmarks are abundant seafloor features worldwide and, in West Florida Shelf waters <110 m deep, are thought to be sites of sediment excavation primarily by red grouper Epinephelus morio, although red snapper Lutjanus campechanus also excavate sediment. During 2014-2017, side-scan sonar (445 kHz) was used to locate and deploy stereo-baited remote underwater video arrays within view of 202 such excavations in waters 17-110 m deep on the West Florida Shelf off the Florida Panhandle and Peninsula. Three excavation habitat classes included 73 isolated excavations on open sand, 74 associated with low-relief hard bottom, and 55 associated with artificial reefs. Physical characteristics of excavations varied between regions, among habitats, and with depth; mean diameter (±1 SE) was 9.9 ± 0.3 m (range: 3-24.6 m). Excavations not around artificial reefs contained 6.9 ± 0.5 m2 (0-27.7 m2) of exposed rock, and epibenthic growth covered 33 ± 2% of the interiors. Members of 99 fish genera were identified. Fish abundance was greatest at isolated excavations which showed similar evenness to excavated artificial reefs; diversity was higher at excavated low-relief hard bottom. L. campechanus was much more common in Panhandle waters, especially at excavated artificial reefs which had subsided 0.8 ± 0.1 vertical meters below the seafloor (i.e. 48 ± 4% of the structure). These biotic and abiotic characteristics of excavations highlight the importance of E. morio’s ecosystem-engineering services and provide new insight into the contributions of L. campechanus in creating or maintaining excavations at natural and anthropogenic habitats.

PDE models for vegetation biomass and autotoxicity

Numerical techniques are widely used to simulate population dynamics in space. In vegetation dynamics, these techniques are very useful to investigate how plants grow, compete for resources, and react to environmental factors within the ecosystem. Plant–soil feedback (PSF) refers to the process where plants or a community alter the biotic and abiotic characteristics of soil that affects the growth of plants or community subsequently growing in that soil. During the last three decades, PSF has been recognized as an important driver for the emergence of vegetation patterns. The importance of studying such vegetation patterns is that they provide an insight into potential ecological changes and illustrate the flexibility and resilience of an ecosystem. Despite the fact that water depletion was once thought to be a major factor in the development of vegetation patterns the existence of patterns in ecosystems without water limitations serves as evidence that this is not the case. In this study, we examine how negative plant–soil feedback contributes to the dynamics of plant biomass. We provide a comparison of different reaction–diffusion PDE models explaining the dynamics of plant biomass in the presence of autotoxicity produced by litter decomposition. We introduce different growth terms, including logistic and exponential, along with additional factors such as extra mortality and inhibitor terms, and develop six distinct models to investigate their individual and combined effects on biomass toxicity distribution. By applying appropriate numerical techniques, we solve the proposed reaction–diffusion PDE models in MATLAB to predict the impact of soil toxicity on plant biomass.

Reaching new lands: Updating the distribution of Angiostrongylus cantonensis in South America with the first record in Argentina.

Angiostrongylus cantonensis, commonly known as the rat lungworm, is a metastrongyloid nematode found primarily not only in tropical and subtropical regions but also in temperate areas and considered the leading cause of eosinophilic meningitis in humans. Synanthropic rodents such as Rattus norvegicus and Rattus rattus are the most frequent definitive hosts of this parasite. The presence of this parasite was detected in the pulmonary arteries of three specimens of R. norvegicus in the city of Buenos Aires representing the species' southernmost known record in natural hosts. Species confirmation was achieved through partial sequences of 18S and COI genes. By comparing the COI gene sequences with those available in GenBank through the construction of a haplotype network, we obtained that the analysed specimen presents high similarity with those reported in Japan and Southeast Asia. All infected rats were captured in an area surrounding a port with significant import and export activity, suggesting that A. cantonensis may have been introduced through commercial ships. Specifically, the parasite was detected in a neighbourhood with vulnerable socio-economic conditions and in a nature reserve, which exhibit biotic and abiotic characteristics conducive to sustaining high-density rat populations, scattered waste, areas of spontaneous vegetation, debris accumulation and flooded areas or lagoons offering suitable habitats for intermediate hosts such as snails. Thus, the close proximity of the port to these sites creates a favourable ecological context for the establishment of A. cantonensis. This study shows the need to conduct research to detect A. cantonensis in non-endemic areas but with the characteristics that promote its arrival and development of its life cycle in order to implement control measures to prevent expansion of this parasite and its transmission to humans and other animals.

Unraveling the habitat preferences, ecological drivers, potential hosts, and auxiliary metabolism of soil giant viruses across China

BackgroundSoil giant viruses are increasingly believed to have profound effects on ecological functioning by infecting diverse eukaryotes. However, their biogeography and ecology remain poorly understood.ResultsIn this study, we analyzed 333 soil metagenomes from 5 habitat types (farmland, forest, grassland, Gobi desert, and mine wasteland) across China and identified 533 distinct giant virus phylotypes affiliated with nine families, thereby greatly expanding the diversity of soil giant viruses. Among the nine families, Pithoviridae were the most diverse. The majority of phylotypes exhibited a heterogeneous distribution among habitat types, with a remarkably high proportion of unique phylotypes in mine wasteland. The abundances of phylotypes were negatively correlated with their environmental ranges. A total of 76 phylotypes recovered in this study were detectable in a published global topsoil metagenome dataset. Among climatic, geographical, edaphic, and biotic characteristics, soil eukaryotes were identified as the most important driver of beta-diversity of giant viral communities across habitat types. Moreover, co-occurrence network analysis revealed some pairings between giant viral phylotypes and eukaryotes (protozoa, fungi, and algae). Analysis of 44 medium- to high-quality giant virus genomes recovered from our metagenomes uncovered not only their highly shared functions but also their novel auxiliary metabolic genes related to carbon, sulfur, and phosphorus cycling.ConclusionsThese findings extend our knowledge of diversity, habitat preferences, ecological drivers, potential hosts, and auxiliary metabolism of soil giant viruses.-qm39L5KUcpZeXpdffa_GXVideo

Biological invasions negatively impact global protected areas

Protected areas underpin global biodiversity conservation and sustainability agendas. Biological invasions increasingly threaten the ecological functioning and long-term conservation value of protected areas, while a lack of information on impact impedes management decisions. We collated data from effects of biological invasions in protected areas to provide the first quantitative analysis of their global impacts. Based on 300 reported effects from 44 invasive species, we show that there are overall negative impacts from invasive species on both biotic and abiotic characteristics of protected areas globally. Impacts were pervasive across population, community, and ecosystem scales, and for the vast majority of invasive taxa with sufficient data. Negative impacts have been incurred around the world, with National Parks and World Heritage Sites in the Neartic and Neotropical regions the most studied. Notwithstanding context-dependencies and uneven research efforts, the recurrent negative impacts of invasive species indicate that current efforts are insufficient to curb current stressors and meet conservation and sustainability targets on land and in water. To address the risk of biological invasions in protected areas, it is imperative to prioritise fundamental research on ecological interactions, establish robust monitoring and prevention programs, and raise awareness through global initiatives.

Effects of habitat biotic features on hymenopteran diversity in East Africa

PurposeOriginally, the coastal region of East Africa was largely covered with coastal forest. With the human settlement, the majority of these forests have been transformed into agricultural land for subsistence farming. Today, only small and geographically isolated forest remnants exist and form a mosaic of different habitat types, including natural, semi-natural and anthropogenic ones. The forest remnants may still represent valuable habitats for typical forest plant and animal species.MethodsIn this study, we surveyed hymenopteran diversity and community composition in different habitat types in southern Kenya. Hereby we considered a small remnant of East African coastal forest, adjoining orchards, shrublands, tree plantations, agricultural fields, and settlements. Hymenoptera represent a large variety of taxa and provide relevant ecosystem services such as pollination to the local people. Hymenoptera were collected with coloured pan traps, identified to family or genus level, and sorted to morphospecies. Habitat parameters such as dead wood, leaf litter, vegetation structure, and the availability of flowers has been assessed for each study site.ResultsIn total, we found 419 Hymenoptera individuals of 153 morphospecies. The different habitat types showed distinct species communities of Hymenoptera. Increasing shrub layer and increasing herb cover had a negative effect on hymenopteran species richness and abundance. Flowers, trees, leave litter, and deadwood showed no significant effect on hymenopteran diversity.ConclusionOur results underline that small-scale habitat diversity lead to high overall diversity of Hymenoptera. Implications for insect conservation: The coastal forest remnant still holds a unique hymenopteran community with 20 Hymenoptera species exclusively found in this habitat type. It is thus of very high conservation value.

Aspects of the demography of two Podarcis muralis populations in anthropogenic modified habitats in western France, based on a non-invasive sampling method

Urbanisation impacts on both abiotic and biotic characteristics of the environment and is likely to bring new selective pressures on animal species living within these areas. The common European wall lizard Podarcis muralis adapts well to urbanisation and indeed may be described as the archetypical urban lizard. In this paper we investigated some aspects of the demography of two populations of P. muralis from western France, one living in a hedgerow system situated in an agricultural area on the edge of a village and a second in an urban garden. The active year in both populations was from February–March until October–December, the latter in the urban garden where temperatures were higher. Numbers decreased from around June then increased again during September but this varied annually and between populations. Diversity and equality indexes for both populations were high, especially in females, indicating a range of individuals and their frequency of presence. Both populations were therefore stable despite only limited numbers of lizards being present for more than one year. Male lizards with high presence were more frequently seen in the company of females than males that were seen less frequently. Hatchling lizards were seen from June after the spring mating period with a second period of hatchlings appearing during autumn. This supports the notion that females annually deposit two clutches of eggs in the area. Keywords: lizards, Podarcis muralis, demography, western France, non-invasive sampling

Łączność hydrologiczna, strukturalna i ekologiczna funkcjonalność meandrującego ekosystemu delty Dunaju

The pressure control of the climate change and anthropogenic factors have consequences on the ecological systems, generating structural changes. The abiotic (i.e., water hydrology and hydraulics, sediment load, water physic-chemistry) and biotic (i.e., biodiversity, structure and functionality of food webs) characteristics of river-channels-lakes from deltas depend on several factors; however, the main driver of these characteristics is represented by the hydrologic connectivity with the main stem of the river. Floodplain lakes can be permanently, temporarily or disconnected with the main stem of the river producing interruptions in the transfer of fresh water and thus affecting benthic macroinvertebrates, by decrease in their population, diversity and even loss of sensitive taxa. Multidisciplinary investigations (hydrodynamics, sedimentological and ecological measurements and analyses) were made to investigate a river-channel-lake site type situated on the St. George branch formed by a cutoff meander (Mahmudia meander), a connective channel (Uzlina Canal) and a lake (Uzlina Lake) to observe how much the fresh water and sediment input to the delta depressions is affected by the structural changes of the meander physiography. The Mahmudia meander was rectified 40 years ago and the response of the channel consisted in a very fast silting of the former meander, currently receiving less than 5% of the upstream water and sediment discharge. The lateral connectivity with the deltaic depressions thought the lateral canals is compromised.

Effects of abiotic restoration through rock addition on invertebrate functional diversity in native temperate grasslands

Invertebrates account for over 90% of all described species and provide crucial ecosystem services. Land clearing, including the removal of abiotic habitat features, threatens invertebrate biodiversity, making environmental restoration crucial for conservation. However, little is known about the effects of abiotic restoration compared to the restoration of biotic features. To determine if rock addition increased invertebrate biodiversity, we introduced 120 t of rocks to 10 sites across five grassland reserves in the Australian Capital Territory in a before‐after‐control‐impact design. We sampled invertebrates using pitfall traps before treatment in 2016 and after rock addition in 2019 (during record‐breaking drought). We recorded 29,164 individual invertebrates from 19 orders and undertook a functional trait‐based analysis of rock effects on the invertebrate community. No effects of rock addition were observed on the probability of occurrence, richness, diversity, community similarity, or abundance of any taxonomic or functional group. The abundance of snare‐building spiders and large ants was higher in the control plots at the end of the experiment. These abundance responses in 2019 did not differ from the control or treatment plots in 2016. Thus, some combination of drought and rock addition appears to have neutralized a positive temporal change that was evident without rocks. Despite a regionwide, replicated restoration effort and an extensive functional analysis of invertebrate communities, very little positive response to rock addition was recorded. Rock addition did not have a negative effect on grassland invertebrate biodiversity and may still be beneficial to the long‐term conservation and restoration of vertebrate and invertebrate communities.

Assessing the impact of an integrated educational program on Greek students' knowledge about coastal lagoons and attitudes towards marine environment conservation

The primary objective of this study is to contribute to the conservation and sustainable use of seas by promoting Ocean Literacy. It investigates the impact of an educational program on Greek primary and secondary public school students' knowledge about coastal lagoons and attitudes towards marine environment conservation. An educational resource titled “Exploring the Coastal Lagoons” was developed to facilitate the non-formal educational intervention. The program involved classroom, fieldwork/outdoor and laboratory activities, focusing on enhancing understanding of coastal lagoons' abiotic and biotic characteristics and human interconnection. Results showed improved knowledge and slightly more positive attitudes after the didactic intervention. The study underlines the effectiveness of targeted educational interventions in marine sciences, suggesting that non-formal educational settings influence student outcomes more than family or informal sources. Younger students appeared more adaptable and responsive to educational stimuli. The study advocates for refined educational strategies integrating cognitive and emotional elements, emphasizing real nature experience.

What are the drivers of female success in food-deceptive orchids?

A large suite of floral signals, and environmental and biotic characteristics influence the behavior of pollinators, affecting the female success of food-deceptive orchids. In this study, we examined the many factors shaping the reproductive output of three orchid taxa: Dactylorhiza majalis, D. incarnata var. incarnata, and D. fuchsii. We applied a statistical model to correlate female success (number of fruit sets) with individual characteristics (plant and inflorescence height, number of flowers, and spur length), number of pollinaria removed, flowering time, and density of floral units of co-flowering rewarding plants. Our findings suggested that the broad spectrum of variations in Dactylorhiza's morphological traits, floral display, and flowering phenology within different environmental contexts has a significant impact on their reproductive success. The number of fruits increased with an increase in the number of pollinaria removed in the studied Dactylorhiza taxa. In contrast, a higher number of flowers per inflorescence and higher inflorescences in relation to individual height always decreased fruit set. We observed that low number of co-flowering rewarding plants in populations could affect the Dactylorhiza reproductive output as magnets and competitor plants. The synchronization of flowering, or lack thereof, between Dactylorhiza and rewarding plants can limit reproductive success. This demonstrates that the food deception strategy is multidirectional, and reproductive output can vary considerably both spatially and temporally within the context of this strategy.

Microclimatic Influences on the Abundance of Three Non-Troglobiont Species

Subterranean environments are often characterized by a natural gradient of microclimatic conditions and trophic resources, showing a higher trophic availability and a lower microclimatic stability in the shallowest area (close to the cave entrance), while the opposite occurs in the deepest sections. The shallowest areas of subterranean environments (e.g., the entrance and twilight zone, Mesovoid Shallow Substratum) act as ecotones between the surface habitats and the deep areas, creating a particular habitat which can be exploited by numerous species with different degrees of adaptation to subterranean environments. Species living in these ecotones may hold a key role in sustaining the entire ecosystem, as they are likely one of the major drivers of allochthonous organic matter. Indeed, these species are usually facultative cave-dwellers, meaning that they are able to exit and forage on the surface. Once these species are back inside the cave, they provide the local community with different typologies of organic matter (e.g., feces, eggs), which represent one of the most important sources of organic carbon. Therefore, studying which ecological features may exert significant effects on the abundance of these species may be of great help in understanding the ecosystem dynamics and the functional role of each species. In this study we analyzed the data collected through a year-round monitoring program, aiming to assess the potential effects that both abiotic and biotic features may have on the abundance of three facultative cave species. We focused on seven caves located in Monte Albo (Sardinia, Italy). The cave environments were divided into 3-meter sectors, and within each cave sector, microclimatic and biological data were seasonally recorded. We focused on the following facultative cave species: the spiders Metellina merianae and Tegenaria sp. and the snail Oxychilus oppressus. Different relationships were observed between the ecological features and the abundance of the three species. The two spiders were more abundant in warmer cave sectors closer to the cave entrance, especially the M. merianae. On the other hand, the snail tended to be more abundant farther from the cave entrance and in more illuminated cave sectors, probably because sunlight promotes the abundance of some of its trophic resources (e.g., lichens, vegetation). Furthermore, O. oppressus was the only species whose abundance and cave distribution was significantly affected by seasonality. This study provides useful and novel information to understand the population dynamics of facultative cave species and their role in subterranean ecosystems.

A Geographic Object-Based Image Approach Based on the Sentinel-2 Multispectral Instrument for Lake Aquatic Vegetation Mapping: A Complementary Tool to In Situ Monitoring

Aquatic vegetation is an essential component of lake ecosystems, used as a biological indicator for in situ monitoring within the Water Framework Directive. We developed a hierarchical object-based image classification model with multi-seasonal Sentinel-2 imagery and suitable spectral indices in order to map the aquatic vegetation in a Mediterranean oligotrophic/mesotrophic deep lake; we then applied the model to another lake with similar abiotic and biotic characteristics. Field data from a survey of aquatic macrophytes, undertaken on the same dates as EO data, were used within the accuracy assessment. The aquatic vegetation was discerned into three classes: emergent, floating, and submerged aquatic vegetation. Geographic object-based image analysis (GEOBIA) proved to be effective in discriminating the three classes in both study areas. Results showed high effectiveness of the classification model in terms of overall accuracy, particularly for the emergent and floating classes. In the case of submerged aquatic vegetation, challenges in their classification prompted us to establish specific criteria for their accurate detection. Overall results showed that GEOBIA based on spectral indices was suitable for mapping aquatic vegetation in oligotrophic/mesotrophic deep lakes. EO data can contribute to large-scale coverage and high-frequency monitoring requirements, being a complementary tool to in situ monitoring.

An updated checklist of Myctophids of Western Indian Ocean with 6 new records

The Western Indian Ocean (WIO) encompass distinct ecosystems with differing oceanographic and biotic characteristics. This paper provides a comprehensive documentation on the myctophid diversity of WIO at depths between 80 and 600 m, based on field data from 74 stations. A total of 59 species of myctophids were recorded from WIO during the study which includes 6 new records. The new records include Bolinichthys nikolayi, Diaphus theta, Lampanyctus crocodilus, Lampanyctus macdonaldi and Lampadena urophaos from Western Equatorial Indian Ocean, and Diaphus similis from South Eastern Arabian Sea. Based on sampling data and the information from secondary data, the number of myctophid species in the WIO is revalidated to 159 species. The myctophid species from the Western Indian Ocean north of 15°S clearly indicates presence of distinct myctophid assemblages in the study area, representing the eco-regions North Eastern Arabian Sea (NEAS), South eastern Arabian Sea (SEAS) and Western equatorial Indian Ocean (WEIO). Present study reports 16 species from NEAS, 45 species from SEAS and 55 species from WEIO. WEIO accounts for 70–90% of the observed species diversity of WIO. Average dissimilarity in species assemblages between NEAS and SEAS was 64%, between SEAS and EIO 75%, and between NEAS and WEIO was 84%. This is the first detailed report on the myctophid species diversity along the 23.5°N latitude (lat), 55°E longitude (long) and 23.5°S lat, 74°E long. Updated checklist of myctophids in the Western Indian Ocean is also included in the paper.

Pontederia crassipes invasiveness on Jeju island is linked to a decline in water pH and climate change-driven overwintering

Freshwater ecosystems are vulnerable to the invasion of exotic aquatic plant species because of the great likelihood of the introduction of exotic species, and the lack of barriers that block introduced species. Water hyacinth, Pontederia crassipes Mart., is one of the world’s most invasive alien plant species damaging freshwater ecosystems worldwide. Here, we monitored the water hyacinth population on Jeju island, Korea, to assess current invasion risks. Furthermore, we investigated how water hyacinth affects water pH because pH is an important determinant of the distribution of other aquatic plants, and thus a good indicator of aquatic ecosystem health. Water containing water hyacinth had a pH of 5.3, while that with water hyacinth and soil had a pH of 4.8 72 hours after the start of the experiment. Water hyacinth extracts contained shikimic acid, stearic acid, and palmitic acid, which are possible compounds that caused a decline in water pH. Water hyacinth also inhibited the growth of the aquatic plant species, Spirodela polyrhiza and Lemna perpusilla. These results imply that invasion of water hyacinth adversely impacts the abiotic and biotic characteristics of aquatic ecosystems. Moreover, monitoring the water hyacinth population suggests that this invasive aquatic plant overwinters on Jeju island. Therefore, regular monitoring and subsequent control of water hyacinth population can prevent its expansion in the aquatic habitats of Jeju island and the southern region of the Korean peninsula.