Higher Taxonomic Richness Research Articles

Diversity and distribution patterns of macrofauna polychaetes (Annelida) in deep waters of the Southwestern Gulf of Mexico

The distribution and composition at the genus level of polychaetes greater than 500 μm of 54 sites in the southwestern Gulf of Mexico in a depth range of 185–3762 m were analyzed. Samples were collected on board the R/V Justo Sierra (Universidad Nacional Autónoma de México) in two cruises carried out in June 2015 and September 2016. Sixty-nine genera belonging to 33 families were recorded. The families with the highest abundance were: Spionidae, Paraonidae, Pilargidae and Capitellidae. Spionidae, Capitellidae and Paraonidae families presented the highest genus richness. The highest abundance was observed in the southern region of the study area and in the upper bathyal zone while the highest taxonomic richness was registered in the Campeche Bay, in the northwestern region of the study area and in intermediate depths. Polychaeta community functional diversity (bioturbation traits and feeding guilds) was also analyzed. A general decrease in functional diversity was observed as depth increased, presenting a partial biodiffusors and deposit-feeders dominance in the deepest zones. Distribution was highly related with depth, sediment granulometry, temperature and dissolved oxygen concentration of the bottom water.

Spatial and Short-Term Temporal Patterns of Octocoral Assemblages in the West Philippine Sea

Octocorals are relatively understudied than other coral reef organisms despite their ecological and economic values. The Philippines is known to have high marine biodiversity, but information on octocorals is lacking. This study investigated spatial and temporal variations in the assemblage of octocorals in selected reef sites in the West Philippine Sea (WPS)- the Kalayaan Island Group (i.e., Pag-asa, Sabina, Lawak, and Northeast Investigator) and Ulugan in 2017 and 2019. Results showed high octocoral taxonomic richness (at least 10 families) in the study sites. Mean percent octocoral cover in WPS was 5.35% SE ± 0.55, with Sabina having the highest octocoral cover in both years. Significant differences in octocoral cover were observed among sites in both years, but among-station differences were only observed in 2017. Octocoral assemblage also differed among sites in both years (ANOSIM:R> 0.5,p< 0.05), wherein different octocoral taxa dominated in different sites. In particular, variations were driven by high cover of holaxonians, nephtheids, and coelogorgiids in Sabina, and clavulariids, tubiporiids, and xeniids in Northeast Investigator in 2017. In 2019, significant variations were driven by high cover of helioporiids in Pag-asa, while Sabina had higher abundance of holaxonians, nephtheids, alcyoniids, and xeniids. Short-term temporal variation on octocoral cover in monitoring stations in Pag-asa was not observed (Kruskal-Wallis,p> 0.05), although the overall mean octocoral cover increased from 1.23% ± SE 0.47 in 2017 to 2.09% SE ± 0.37 in 2019. Further, there was no significant change in the octocoral assemblage in Pag-asa between years (ANOSIM,R= 0.11,p= 0.07). This study highlights high octocoral taxonomic richness in the WPS relative to other sites in the Indo-Pacific Region and provides baseline information on the octocoral assemblages, which can be useful for future ecological studies and marine biodiversity conservation efforts.

A importância de planícies de inundação: três décadas de programa de monitoramento de macroinvertebrados aquáticos em uma planície de inundação Neotropical

Abstract Aim Wetland areas have high environmental complexity and support high biodiversity. Therefore, global efforts are required to preserve these areas. Here, we show the results of three decades of monitoring programs regarding macroinvertebrate species from the upper Paraná River floodplain, which is an important wetland conservation area in the neotropics. Methods We searched the literature from 1990 to 2020 and selected studies that addressed questions related to benthic or macrophyte-associated macroinvertebrates in the study area. Results We retained 92 articles that matched the criteria. We noticed that the number of publications increased after 2009, and most studies were related to lentic environments. Sediment was the most studied substrate, showing the highest taxa record and diversity, followed by aquatic macrophytes. We found records of 517 taxa, from which the families Chironomidae, Cyprididae, and Naididae presented the highest taxonomic richness. The taxa richness observed in our study was lower than the bootstrap richness estimated. Conclusions The lack of signs of curve stabilisation through time for both observed and estimated taxa richness could indicate the macroinvertebrate richness from the upper Paraná River floodplain must be underestimated. In this way, once most of the studies reported results related to long-term ecological research, we argue for the continuity of such studies in floodplains as a powerful tool to assess biodiversity, which can provide useful data for the creation of conservation strategies that enhance the maintenance of biodiversity in such areas.

Disentangling responses to natural stressor and human impact gradients in river ecosystems across Europe

Abstract Rivers are dynamic ecosystems in which both human impacts and climate‐driven drying events are increasingly common. These anthropogenic and natural stressors interact to influence the biodiversity and functioning of river ecosystems. Disentangling ecological responses to these interacting stressors is necessary to guide management actions that support ecosystems adapting to global change. We analysed the independent and interactive effects of human impacts and natural drying on aquatic invertebrate communities—a key biotic group used to assess the health of European freshwaters. We calculated biological response metrics representing communities from 406 rivers in eight European countries: taxonomic richness, functional richness and redundancy, and biomonitoring indices that indicate ecological status. We analysed metrics based on the whole community and a group of taxa with traits promoting resistance and/or resilience (‘high RR’) to drying. We also examined how responses vary across Europe in relation to climatic aridity. Most community metrics decreased independently in response to impacts and drying. A richness‐independent biomonitoring index (the average score per taxon; ASPT) showed particular potential for use in biomonitoring, and should be considered alongside new metrics representing high RR diversity, to promote accurate assessment of ecological status. High RR taxonomic richness responded only to impacts, not drying. However, these predictors explained little variance in richness and other high RR metrics, potentially due to low taxonomic richness. Metric responsiveness could thus be enhanced by developing region‐specific high RR groups comprising sufficient taxa with sufficiently variable impact sensitivities to indicate ecological status. Synthesis and applications. Metrics are needed to assess the ecological status of dynamic river ecosystems—including those that sometimes dry—and thus to identify priority sites requiring action to tackle the causes of environmental degradation. Our results inform recommendations guiding the development of such metrics. We propose concurrent use of richness‐independent ‘average score per taxon’ indices and metrics that characterize the richness of resistant and resilient taxa. We observed interactions between aridity, impacts and drying, highlighting that these new metrics should be region specific, river type specific and adaptable, promoting their ability to inform management actions that protect biodiversity in river ecosystems responding to climate change.

Gut Microbiome of Wild Baltic Salmon (Salmo salar L.) Parr.

Gut microbiota of wild Baltic salmon (a sub-population of Atlantic salmon Salmo salar L.) parr was first analyzed using microbial profiling of the 16S rRNA gene (V3-V4 region) and high taxonomic richness was revealed. At the phylum level, the gut microbiota was dominated by Firmicutes, Actinobacteria, and Proteobacteria, the most numerous of which were Firmicutes. The phylum Tenericutes (mainly assigned to Mycoplasmataceae), which is common both in wild North- and East- Atlantic salmon parr, was not detected in Baltic salmon parr. Across all samples, unique amplicon sequence variants (ASVs) belonging to the unclassified Bacilli, Actinomycetales, and Rhizobiales were identified as the major taxa. Fifteen ASVs at the family level were found in all gut samples of Baltic salmon parr, the majority of which were Mycobacteriaceae, Cryptosporangiaceae, Microbacteriaceae, and Planctomycetaceae. At the genus level, Mycobacterium, Clostridium sensu stricto, and Hyphomicrobium were dominant but at low levels in all gut samples. Our study has revealed that the gut microbial community of wild Baltic salmon parr differs from those of wild North- and East-Atlantic salmon parr. This can be due to biogeographical differences or host-selective pressures, as the Baltic salmon population is believed to have split from the Atlantic salmon population in the Ancylian period.

Inshore or offshore? The Neolithic fishermen of Ra’s al-Hamra (RH-6, RH-5, Muscat, Sultanate of Oman)

Ra’s al-Hamra 6 (RH-6) and Ra’s al-Hamra 5 (RH-5) are two of the most important Neolithic coastal sites in the Sultanate of Oman. Located in the capital Muscat, they have supplied an important corpus of fish bones and revealed a high taxonomic richness in the different assemblages. The results provided information on fishing practices that held an important role in the subsistence strategies of the inhabitants during the two millennia of occupation (sixth to fourth millennia BC). Pelagic species (jacks and kawakawa/tunas) were largely dominant throughout both occupations, calling into question the interpretation of inshore or offshore fishing; these fish could have been caught with a hook-and-line or by setting nets at a reasonable distance from the coast. However, the inhabitants also had to supplement this subsistence by catching demersal fish and small fish, caught from the cliff, in the estuary or the mangrove. At both sites, the inhabitants clearly exploited the different nearby inshore environments: coastal open water, reefs, estuary, and mangrove. Moreover, the high fish richness (69 genera at RH-6; 35 genera at RH-5) indicates that both sites could have been occupied on a year-round basis.

A higher taxonomic richness does not ensure the functional resilience of saproxylic beetle communities in evergreenQuercusforests

1. Despite the fact that insects are suffering a global decline, little is known about the extent to which species loss affects functional diversity. Thus, to understand the relationship between taxonomic and functional diversity metrics, we focused on saproxylic beetles, which perform vital functions in forest ecosystems.2. Beetles were collected monthly for a year using flight interception traps placed in three protected areas of mature evergreen MediterraneanQuercusforests. Five morphological traits, one phenological trait, and one physiological surrogate trait were measured, and trophic guild identities were determined. Two taxonomic and six functional metrics were assessed to determine their relationships.3. Taxonomic and functional diversity patterns, as well as trait patterns, differed depending on the protected areas, as they were influenced by habitat and microhabitat characteristics. Generally, a high number of species tended to support high values of functional richness, but did not ensure high values of functional redundancy, thus affecting the resilience of communities.4. A 5% of species loss strongly affected the functional redundancy of communities, making them more vulnerable. Functional richness, however, was not affected, since it was associated with a high number of redundant species. Thus, the way species loss affected communities is highly dependent on the presence of rare or redundant species.5. Taxonomic and functional diversity metrics should be used as complementary tools for conservation purposes. In this way, the comparative analysis of taxonomic and functional patterns may help to predict the vulnerability of saproxylic assemblages to changes or disturbances.

Influence of micro-habitats on the distribution of macroinvertebrates in Burkina Faso (West Africa)

In this work, we assessed micro-habitat's influence on the distribution of macroinvertebrates in lake Ziga in Burkina Faso from July to December 2016. The water quality variables were measured in situ and the macroinvertebrates were collected with a hand net. The organisms were identified to the lower taxonomic resolution as possible. The results show that the temperature is globally warm, characteristic of tropical area, with a good oxygen content and pH close to neutral. We found five micro-habitats, mainly dominated by fine substrates (32.5%) and aquatic plants (25.83%). The stone, roots and dead woods represented less than 20%. In total, 3,773 individuals of macroinvertebrates were collected. These individuals belong to 33 taxa and three classes. The insects class is the most abundant (88.22%) and the most diversified (24 taxa, 72.72%). The highest taxonomic richness is observed in aquatic plants and root zones. The diversity and density of the macroinvertebrate community varies according to micro-habitats but not according to the size of their surface area. The results showed that coleopterans and hemipterans were strongly and positively correlated to transparency and conductivity (adjusted r>60%, P <0.05). In the local area, the results showed that macroinvertebrates' diversity and distribution are more linked to habitat availability. Our findings reveal a good habitat condition of the lake, and can be served as reference site and hostpot of aquatic biodiversity in the area.

Floristic surveys of some lowlands polluted of a tropical urban area: the case of Yaounde, Cameroon

Lowlands of Yaounde, Cameroon are facing soil pollution due to all type of organic and inorganic wastes, particularly heavy metal due to anthropogenic activities. Identifying macrophytes species able to develop on heavy metal polluted soils remains an essential step in the phytoremediation process which used living green plants. In this study, floristic surveys using the quadrat method were conducted in lowland areas surrounded by heavy metal pollution sources activities of Yaounde to identify macrophytes species with phytoremediation capacities. Inventories were conducted in 11 polluted lowlands and results were compared to control which is an unpolluted area. A total of 189 species belonging to 138 genera distributed in 63 families were identified on polluted sites. Macrophytes diversity was higher in each polluted site compared to the control. Poaceae, Asteraceae, Fabaceae, Malvaceae, and Solanaceae families showed a higher taxonomic richness on polluted sites (23, 20, 14, 12, and 12 taxa, respectively). Shannon diversity index of the lowlands polluted sites 2.69 was significantly higher than the control 2.3. Pielou equitability index in contaminated sites (0.459–0.847) was not significantly different from the control 0.747. Based on the abundance and relative frequency (≥10%), our results show that more than 10 macrophytes species existing in these lowlands areas could be tested in preliminary trials to investigate their phytoremediation/cleaning-up capacities on polluted soils in the tropical zone. Novelty and impacts of the submission This study presents original results for field surveys in lowland sites polluted in Yaounde-Cameroon. The screening of 11 polluted lowlands compared to a natural lowland (unpolluted), made it possible to identify species which may exhibit the best capacities to adapt to environmental changes and to develop in contaminated areas, in particular heavy metals. This work can be a preliminary study around the species growing in contaminated lowlands. Thus, this study can be reproduced in other regions, to compare the results obtained and identify potential plants for the lowlands remediation in Cameroon.

The stem-archosaur evolutionary radiation in South America

The oldest archosauromorphs (dinosaurs, birds, crocodiles, and their stem-taxa) are recorded in middle−upper Permian rocks, but it was not after the Permo−Triassic mass extinction that the group shows a substantially high taxonomic richness and ecomorphological disparity. The early evolutionary history of the Archosauromorpha during the Early and Middle Triassic is mainly based on fossils recovered from rocks in southern Africa, Europe and Asia, whereas South America possesses a more complete fossil record of the group only in the Late Triassic. Here we revisit, discuss, and reanalyse the non-archosaurian archosauromorph fossil record of the current-day South America. The Early Triassic archosauromorph record in this continent is still scarce, but it documents the early evolution of the group in western Pangaea and is crucial to understand more globally the biotic recovery after the Permo−Triassic mass extinction. The Middle Triassic record is extremely scarce, but the Late Triassic archosauromorph assemblage of South America is among the most diverse and abundant worldwide. The last decade has witnessed a considerable improvement in our knowledge of the record, taxonomy, phylogeny, and macroevolution of the group with the input from the South American fossils. Nevertheless, a considerable amount of research is needed and ideally should be focused on some particular aspects of the Triassic evolutionary radiation of Archosauromorpha. Among them, the Early Triassic record should be expanded, more numerous and more complete Middle Triassic archosauromorph specimens are crucial to have a more complete picture of the evolution of the group, and the taxonomy of groups like proterochampsids and hyperodapedontine rhynchosaurs should be clarified through detailed anatomical work.

Raptor breeding sites as a surrogate for conserving high avian taxonomic richness and functional diversity in urban ecosystems

Preserving biodiversity and ecosystem functions in rapidly increasing urban areas has become a focal issue of conservation science. With limited budgets and human resources, a potentially efficient conservation strategy is to prioritize important areas in urban ecosystems, based on raptor habitats. Here, northern goshawk (Accipiter gentilis) breeding sites in urban Kanagawa, Japan were used to explore the effectiveness of raptor habitats as conservation surrogates for biodiversity and ecosystem function. The presence of birds was recorded within 500 m of 37 goshawk breeding sites through point counts in the breeding season of 2019. Species richness and dendrogram-based functional diversity (FD) were then determined as measures of biodiversity and ecosystem function, respectively. As controls, 50 sites with landscape compositions similar to goshawk breeding sites were also evaluated. The analysis involved two generalized linear models using species richness and FD as response variables and the presence/absence of goshawk breeding sites as covariates. Goshawk breeding sites had a significant positive effect on species richness and FD, explaining most of their variance (species richness: 63.0%, FD: 56.9%). In conclusion, this study confirmed that goshawk breeding sites that maintain high urban biodiversity and ecosystem function can be used to prioritize and preserve important areas for conservation.

To composite or replicate: how sampling method and protocol differences alter collected stream invertebrates and associated bioassessment metrics.

Aquatic invertebrates are excellent indicators of ecosystem quality; however, choosing a sampling method can be difficult. Each method and associated protocol has advantages and disadvantages, and finding the approach that minimizes biases yet fulfills management objectives is crucial. To test the effects of both sampling methods and sample handling-i.e., to composite samples or leave them as replicates-we collected aquatic invertebrates from the Niobrara River at Agate Fossil Beds National Monument, Nebraska, using three methods and two sample handling protocols. We compared aquatic invertebrate assemblages collected with a Hester-Dendy multi-plate sampler, Hess sampler, and a D-frame dipnet. We calculated six common bioassessment metrics from composite (combined) and replicate (separate) samples. Hess samples contained the highest taxonomic richness (capturing 77% of all taxa observed) and dipnet samples the least (47%). Hester-Dendy samples had the greatest proportion of Ephemeroptera, and Ephemeroptera, Plecoptera, and Trichoptera (EPT). Dipnet samples had the lowest evenness values. In terms of sample handling, composite samples had inflated richness, diversity, and evenness compared with replicate samples, but bioassessment metrics calculated from proportions or averages (i.e., Hilsenhoff's Biotic Index and the proportion of EPT taxa) did not differ between them. The proportion of invertebrate groups from composite samples were not statistically different among sampling methods, but several groups differed between replicate samples collected by different methods. Ultimately, we recommend collecting replicate samples with a Hess sampler when the goal of the study is to detect ecosystem change, among locations or differences in variables of interest.

Combined impact of pesticides and other environmental stressors on animal diversity in irrigation ponds.

Rice paddy irrigation ponds can sustain surprisingly high taxonomic richness and make significant contributions to regional biodiversity. We evaluated the impacts of pesticides and other environmental stressors (including eutrophication, decreased macrophyte coverage, physical habitat destruction, and invasive alien species) on the taxonomic richness of freshwater animals in 21 irrigation ponds in Japan. We sampled a wide range of freshwater animals (reptiles, amphibians, fishes, mollusks, crustaceans, insects, annelids, bryozoans, and sponges) and surveyed environmental variables related to pesticide contamination and other stressors listed above. Statistical analyses comprised contraction of highly correlated environmental variables, best-subset model selection, stepwise model selection, and permutation tests. Results showed that: (i) probenazole (fungicide) was a significant stressor on fish (i.e., contamination with this compound had a significantly negative correlation with fish taxonomic richness), (ii) the interaction of BPMC (insecticide; also known as fenobucarb) and bluegill (invasive alien fish) was a significant stressor on a "large insect" category (Coleoptera, Ephemeroptera, Hemiptera, Lepidoptera, Odonata, and Trichoptera), (iii) the interaction of BPMC and concrete bank protection was a significant stressor on an "invertebrate" category, (iv) the combined impacts of BPMC and the other stressors on the invertebrate and large insect categories resulted in an estimated mean loss of taxonomic richness by 15% and 77%, respectively, in comparison with a hypothetical pond with preferable conditions.

Hedgerows support rich communities of harvestmen (Opiliones) in upland agricultural landscape

Hedgerows play important roles in agricultural landscapes and they increase biodiversity by providing habitat refugia for species sensitive to agricultural disturbance. We have studied the characteristics of the communities of harvestmen (Opiliones) inhabiting hedgerows. Harvestmen are terrestrial arachnids associated with soil surface and subsurface and sensitive to land-use and disturbance. We were specifically interested in quantifying how hedgerow characteristics (e.g., elevation, length, width, connectivity, and plant diversity) affect harvestman diversity and community composition. We expected harvestman diversity and community composition to be positively related to both hedgerow size (area, length, width) and biological attributes of hedgerows (e.g., connectivity, plant community diversity). We surveyed hedgerow characteristics and harvestman communities of 20 hedgerows in an upland agricultural landscape in the Western Carpathians. Hedgerow characteristics were measured in the field or derived from GIS layers and we used correlation and ordination methods to relate them to harvestman community metrics. We found surprisingly high taxonomic richness of harvestmen within the studied hedgerows (15 species). Importantly, the Shannon index of harvestman communities was positively related to hedgerow length and hedgerow tree layer species richness and diversity. Harvestman community composition varied with hedgerow area and width. Despite their small total area, hedgerows represented an important habitat for diverse harvestman communities and hedgerow attributes such as size and tree diversity significantly affected the composition and the Shannon index of harvestman communities. Thus, greater lengths and widths of hedgerows can provide habitats for a higher Shannon index of harvestman communities, within surrounding agricultural landscapes.

Lake-depth related pattern of genetic and morphological diatom diversity in boreal Lake Bolshoe Toko, Eastern Siberia.

Large, old and heterogenous lake systems are valuable sources of biodiversity. The analysis of current spatial variability within such lakes increases our understanding of the origin and establishment of biodiversity. The environmental sensitivity and the high taxonomic richness of diatoms make them ideal organisms to investigate intra-lake variability. We investigated modern intra-lake diatom diversity in the large and old sub-arctic Lake Bolshoe Toko in Siberia. Our study uses diatom-specific metabarcoding, applying a short rbcL marker combined with next-generation sequencing and morphological identification to analyse the diatom diversity in modern sediment samples of 17 intra-lake sites. We analysed abundance-based compositional taxonomic diversity and generic phylogenetic diversity to investigate the relationship of diatom diversity changes with water depth. The two approaches show differences in taxonomic identification and alpha diversity, revealing a generally higher diversity with the genetic approach. With respect to beta diversity and ordination analyses, both approaches result in similar patterns. Water depth or related lake environmental conditions are significant factors influencing intra-lake diatom patterns, showing many significant negative correlations between alpha and beta diversity and water depth. Further, one near-shore and two lagoon lake sites characterized by low (0-10m) and medium (10-30m) water depth are unusual with unique taxonomic compositions. At deeper (>30m) water sites we identified strongest phylogenetic clustering in Aulacoseira, but generally much less in Staurosira, which supports that water depth is a strong environmental filter on the Aulacoseira communities. Our study demonstrates the utility of combining analyses of genetic and morphological as well as phylogenetic diversity to decipher compositional and generic phylogenetic patterns, which are relevant in understanding intra-lake heterogeneity as a source of biodiversity in the sub-arctic glacial Lake Bolshoe Toko.

Hypoxia in mangroves: occurrence and impact on valuable tropical fish habitat

Abstract. Intertidal mangrove forests are harsh environments that can naturally experience hypoxia in association with low tide. However, we know relatively little about dissolved oxygen (DO) fluctuations and DO-induced responses by fish, although DO is a fundamental water quality parameter. This study examines DO as a potential factor regulating the utilisation of intertidal mangrove forests by fish and consequently their widely recognised feeding, refuge and nursery values. We deployed underwater video cameras, coupled with DO and depth loggers, in a mangrove forest to record changes in fish assemblages in response to tidal variations in DO and other associated environmental parameters. Our results indicate that DO underwent extreme tidal fluctuations, reaching levels as low as 14 % saturation. As DO was identified as a significant factor for explaining variability in fish assemblage composition, we further investigated fish responses to DO fluctuations. Higher taxonomic richness and frequencies of occurrence were observed once DO reached 70 %–80 % saturation. More detailed examination revealed species-specific responses. Three distinct patterns of mangrove utilisation in response to DO were identified, driven by apparent taxa's behavioural DO avoidance thresholds. Most taxa did not display any behavioural avoidance, including presence at the lowest DO levels, while other taxa were not observed either below 50 %–60 % saturation or below 70 %–80 % saturation. This implies that tidal migrations, often observed in intertidal environments, could be the result of differential DO tolerances and are not simply initiated by changes in water depth. Taxa remaining in the mangrove forest even at low DO were on average more frequently observed than the other taxa and were mostly species commonly associated with mangrove habitats. This suggests that being adapted to withstand low DO might be an important condition for using mangrove habitats extensively. The need of being tolerant to low DO could constrain fish utilisation and explain the relatively low species richness often observed in other intertidal mangrove forests.

Dípteros acuáticos del departamento del Chocó, Colombia

Se presenta un reporte preliminar sobre la riqueza y distribución de los dípteros acuáticos en el departamento del Chocó, a partir de 490 especímenes (larvas y pupas) de la Colección Limnológica del Chocó (CLCH-Insec, Universidad Tecnológica del Chocó), que corresponden a 18 municipios (entre 5 y 3202 m s.n.m.), 46 corrientes hídricas de diferente orden y 14 ecosistemas lénticos de las cuencas de los ríos Atrato, San Juan y Baudó. Se reportan 12 familias y 30 géneros, de los cuales 4 familias y 16 géneros, son registrados por primera vez para el Chocó. Chironomidae es la familia más abundante y más ampliamente distribuida, mientras que Dixidae y Sciomyzidae son las familias de menor abundancia y distribución. La mayor riqueza taxonómica la registran las familias Culicidae y Ceratopogonidae, con cinco géneros cada una. Las macrófitas son el sustrato con mayor riqueza específica. El mayor registro taxonómico se encuentra en la cuenca del río Atrato, con 11 familias y 24 géneros. Estos resultados permiten evidenciar la enorme diversidad de los dípteros acuáticos en el departamento del Chocó y la necesidad de adelantar nuevas investigaciones que amplíen su conocimiento taxonómico y ecológico en la región.

Benthic diatoms species richness at Dvuyakornaya Bay and other coastal sites of Crimea (the Black Sea) under various environments

First-time research of the pristine water area of Dvuyakornaya Bay (South-Eastern Crimea, Black Sea) revealed high taxonomic richness of benthic diatoms (Bacillariophyta). Altogether, 304 species, 78 genera, 37 families and 20 orders were identified. Among them 68 newly-found species for the Black Sea were marked. The largest species number was marked in the genera Navicula (41 species), Nitzschia (29), Amphora (25), Cocconeis (20), Diploneis (16), Lyrella, Fallacia and Planothidium (10 species respectively). Inter-regional comparative analysis of diatom species richness was carried out using Bray-Curtis similarity coefficient and Venn diagrams. Diatom taxocene of Dvuyakornaya Bay (DB) was compared with Bacillariophyta flora from several Crimean coastal sites under different level of anthropogenic impact, i.e. relatively pristine water area near Cape Fiolent (CF) and heavy polluted Sevastopol Bay (SB) and Balaklava Bay (BB). The highest similarity of species composition (58%) was registered between intact biotopes (DB vs CF) and between heavy polluted water areas (SB vs BB), despite the geographical remoteness of the compared areas, differences in hydrological-hydrochemical conditions and in bottom substrates patterns. The lowest species similarity of diatom taxocenes was observed between SB and CF (32.3%) and between SB and DB (36.5%). It was concluded that the content of technogenic pollutants (trace metals, PCBs, PAHs and pesticides) in the bottom sediments, as well as the heterogeneity of microbiotopes are represent major factors influencing on the species composition of benthic Bacillariophyta in the investigated coastal water areas.

Benthic macroinvertebrate community diversity of Montebello Lakes, Chiapas

Benthic macroinvertebrate community biodiversity of tropical lakes has been rarely addressed. The present study recognizes the taxonomic diversity of the deep benthic macroinvertebrate communities of 18 lakes of the Protected Natural Area Lagunas de Montebello, Chiapas, Mexico. The lakes display different morphometric features and trophic states. Five sampling campaigns were carried out between 2013 and 2016. Forty-nine taxa (14 orders, 25 families, 40 identified genera, and 9 undetermined taxa) were recorded. Taxonomic richness varied between 0 and 19 taxa with a mean of 5 ± 6 taxa. The regional species richness was high compared to other tropical lakes in Mexico and worldwide; the richness per lake was similar to other tropical lakes. Chironomidae was the best-represented family with 17 genera. Even the studied lakes belong to the same lake district, low taxonomic similarity among them was found; 65.3% of genera were found in a single lake. Eutrophic shallow lakes had lower richness (2.5 ± 3.5, 0-5) compared to oligotrophic shallow lakes (5.0 ± 7.1, 0-10), and eutrophic deep lakes had lower richness (2.0 ± 1.8, 0-4) than oligotrophic deep lakes (7.0 ± 6.5, 0-19); nonetheless, we found no statistically significant differences. Eutrophication is reducing deep benthic community diversity, threatening these fragile ecosystems characterized by high taxonomic richness and singularity.

Short-term influence of biochar and fertilizer-biochar blends on soil nutrients, fauna and maize growth

Use of inorganic fertilizers in smallholder cropping systems in Africa is often becoming inefficient due to increasing unresponsiveness to fertilizer application. A study was conducted for 2 years (four seasons) to assess the effects of biochar made from Prosopis juliflora (Sw.) DC. biomass on nutrients, fauna abundance and subsequent influence on maize planted in a nitisol. There were 12 amendments comprising: (i) biochar applied alone at a rate of 5 and 10 Mg ha−1; (ii) three fertilizer types applied separately (di-ammonium phosphate (18:46:0), urea (46:0:0) and composite NPK (23:23:0)); (iii) six fertilizer + biochar blends of the three fertilizer types and two biochar rates (0.05 and 0.1 Mg ha−1); and (iv) a control with no inputs. Treatments were replicated four times in a randomized complete block design. The amendments were applied in the first two seasons, while the last two were used to assess residual effects. At the end of the first two seasons, total C and N were higher in soils where biochar or fertilizer + biochar was applied, with more than 15.0 g C and 1.9 g N kg−1, compared to 10.4 g C and 1.0 g N kg−1 in control plots. Available P and exchangeable K were over 200% and 100% higher in biochar or fertilizer + biochar amended than control soils, respectively. Application of biochar had no effects on macrofauna such as beetles, centipedes, millipedes, termites and ants, but attracted earthworms. Soil that received 10 Mg biochar ha−1 recorded twice the number of earthworms (207 individuals m−2) compared to soil with 5 Mg biochar ha−1 (105 individuals m−2) and control (97 individuals m−2). Soils which received biochar, with or without fertilizer, had higher taxonomic richness (7.0 species) compared to soils which received DAP (2.8) or NPK (3.8). Nematodes, particularly bacterivorous groups, decreased by more than eight times with biochar application. In the first and second seasons, 5.6 Mg maize grain yield ha−1 was obtained from plots amended with biochar (without fertilizer), which was about six times higher than that harvested from unfertilised control at 0.9 Mg ha−1. Yield differences in plots where fertilizer was applied with or without biochar were not significant. Yield in the third and fourth seasons declined to 3.2 and 1.5 Mg ha−1, irrespective of fertilizer type or biochar amounts.