Sandy Substrate Research Articles

Syntaxonomy and ecological differentiation of the pioneer vegetation of Ukraine. 2. Helichryso-Crucianelletea maritimae, Festucetea vaginatae, Koelerio-Corynephoretea canescentis classes

Pioneer psammophytic vegetation is usually developed on wind-drift sandy substrates such as arenas, spits, beaches, river terraces, and this vegetation occupies significant areas in all three natural zones of Ukraine. The Koelerio-Corynephoretea canescentis class was represented by 13 associations, 3 alliances and 1 order; Festucetea vaginatae class by 22 associations, 2 alliances and 1 order; Helichryso-Crucianelletea maritimae by 10 associations, 4 alliances and 1 order. The results of cluster analysis and synoptic tables of the classes are presented. 9 alliances are briefly described. Leading factors of territorial and ecological differentiation are identified. It was found that the territorial distribution of plant communities is influenced by the character of ecotope mesorelief, soil composition and humus horizon thickness, as well as the degree of eolian processes development. The main factors of their ecological differentiation are soil acidity, salt regime and ombroregime. Based on the results of DCA-ordination of syntaxa within certain vegetation classes, it was found that their distribution is influenced by factors that correlate with the environment-specific conditions. It has emerged that an ecological differentiation of syntaxa within Festucetea vaginatae is determined by the integrated effect of gradients, and soil salinity is leading among them. Temperature regime and climate continentality are leading factors in the distribution of syntaxa within the Koelerio-Corynephoretea canescentis class. The gradients of ombroregime and soil humidity have a significant impact. The distribution of communities of the Helichryso-Crucianelletea maritimae class in the ecological space is determined mainly by factors of variability of damping, ombroregime and climate continentality. The author’s syntaxonomic concept assumes the independence of the studied classes: Koelerio-Corynephoretea canescentis, Helichryso-Crucianelletea maritimae and Festucetea vaginatae, conside­ring that the leading factors of community differentiation of the Festucetea vaginatae and Koelerio-Corynephoretea canescentis classes are the origin (genesis) of sandy substrates, as well as soil acidity. Phytosociological analysis of a large number of relevés of coastal littoral vegetation also provides support for independence of the Helichryso-Crucianelletea maritimae and Ammophiletea classes diffe­rent floristically and ecologically. A review of the psammophytic vegetation of Ukraine will determine the place of the selected syntaxonomic units in the pan-European system.

Spatial and temporal variations in depositional systems in the Kazusa Group: insights into the origins of deep-water massive sandstones in a Pleistocene forearc basin on the Boso Peninsula, Japan

A detailed chronostratigraphic framework established by the mapping of tephra key beds and application of oxygen isotopic data allows assessment of the synchroneity and diachroneity of depositional systems formed in coastal and deep-water environments. This framework also allows estimation of the timing of active delivery of coarse-grained sediments beyond the shelf margin in relation to relative sea-level changes. The depositional processes of deep-water massive sandstones (DWMSs) are still enigmatic; their formation is a result of active delivery of sands in association with the supply of organic carbon into deep-water environments. DWMSs are also important as reservoirs for hydrocarbon explorations. This study investigated the origins of DWMSs in the upper Umegase, Kokumoto, and Chonan formations (in ascending order) of the Pleistocene Kazusa Group on the Boso Peninsula, central Japan. Each formation contains several packets of DWMSs that are interpreted to have formed in response to the progradation of gravelly shelf-margin deltas or fan deltas during the falling and lowstand stages of relative sea-level changes controlled primarily by glacioeustasy. The development of DWMSs and associated sandstone beds is interpreted to have been induced by hyperpycnal flows, in association with sediment gravity flows that were initiated by breaching and/or collapse of sandy substrates on the shelf-margin deltas or fan deltas. The timings of the initial and final deposition of the packets vary within and between the formations, and are considered to have been controlled by the interaction between allogenic and autogenic processes operating in the gravelly shelf-margin deltas or fan deltas. A muddy horizon that contains the Lower–Middle Pleistocene Subseries boundary (the base of the Chibanian Stage) in the Kokumoto Formation is also underlain and overlain by the packets and represents a deposit formed in a condensed section in an upper slope environment. This depositional setting may have favored the development of the Global Boundary Stratotype Section and Point (GSSP) for the Lower–Middle Pleistocene Subseries boundary in the formation.

Status, Prospects and Market Potentials of the Sea Cucumber Fisheries with Special Reference on Their Proper Utilization and Trade

Sea cucumbers belonging to the phylum Echinodermata are important marine invertebrates, generally occur in the sandy substrates and rocky shores near the bottom of sea. This review work has been attempted to make an interlink between biological and socio-economical perspectives of sea cucumber because of the high demand in the present world. The outer body part of sea cucumber (bêche-de-mer) has been recognized for producing secondary metabolites including vitamins and triterpenoid glycoside saponins that have profound ecological and bio-medicinal significance. Sea cucumbers are also used to remove arthritis pain, exert wound healing, and nowadays, are utilized in human health therapeutics and Asian folk medicine. Due to higher pharmaceutical, cosmeceutical and nutraceutical values, sea cucumber has become one of the most essential products, and fetched higher market prices and therefore, provide a significant earning source and employment opportunity to the coastal communities in many countries. The sea cucumber and its product have been considered to be the excellent bioresource in the invertebrate fishery, whose harvestings, transporting, handlings, processing and maintenance are easy, convenient and cost-effective. Historically, bêche-de-mer were harvested from the multi-species capture fishery and stored for long times for selling to the businessmen and traders directly on the site. As like other lucrative and expensive food items viz., fish-maws, shark-fins and abalones, sea cucumbers are taken into the account as the high-valued products in the world seafood markets. Nevertheless, bêche-de-mer product supply in the South-East Asian countries has been decreasing day by day because of unstrained harvesting and overexploitation. On the other hand, the marketing structure in these countries is typically ineffective and the trading networks are multifaceted. Due to the lack of proper information, fishermen are not usually getting proper values and actual prices from the sea cucumber products, whereas other distributors and value-chain members have made complex systems, which have led to high cost of the products. The sea cucumber products will still have higher possibility of trading throughout the world markets, that might eventually contribute to the global economy in a very worthwhile, significant and sustainable manner.

Effects of substrate on the physiological characteristics and intestinal microbiota of Echiura worm (Urechis unicinctus) juveniles

The effects of environmental factors on the physiological characteristics of Echiura worm Urechis unicinctus have been widely studied, however, the influences of substrate on this species are still unclear. Differences in the growth performance, physiological response, and intestinal microbiota of U. unicinctus juveniles between the sandy and muddy substrates were evaluated in the present study. The results indicated that the weight gain was significantly higher in U. unicinctus juveniles with the sand bottom compared to the mud group, while the survival rate was obviously lower. The activities of intestinal digestive enzymes and the contents of triglyceride, glucose, and total cholesterol in the coelomic fluids had a significant increase in the individuals with the sandy bottom compared to the mud group. The oxidative stress and intestinal inflammatory were induced by the sandy bottom, meanwhile, the antioxidant system and goblet cells were activated to protect the U. unicinctus juveniles. Focused on the intestinal microbiota of U. unicinctus juveniles, Sphingomonadales, Burkholderiales, and Pesudomonadales were more abundant in the mud group. In contrast, Alteromonadales and Rhodobacterales were enriched in the sand group. Moreover, various correlations were observed between the intestinal bacteria and physiological indices, such as Acinetobacter with the lipoprotein- and hepatic-lipase activities, Shewanella with the superoxide dismutase activities, and Cupriavidus with the malondialdehyde contents.

Compound biogenic structures resulting from ontogenetic variation: An example from a modern dipteran

Several families of Diptera are known to be active burrowers. Fly larvae of the genus Symplecta (family Limoniidae) were observed in a sandy substrate of an orange grove in Lepe, SW Spain. Traces produced by Symplecta display: (1), a proximal segment characterized by a winding furrow trail; (2), an intermediate part consisting of burrow segments arranged in zigzag; and (3), a distal part formed by a complex U-shaped burrow. The most complex morphology is present in the intermediate zigzag burrow system, which varies from irregularly sinuous and curved in its most proximal part to spiraled. In the fossil record, the trace would be ascribed to different ichnotaxa depending on the part preserved. In fact, this is a compound trace recording multiple behavioural patterns. The winding furrow shows affinities with Helminthopsis, the zigzag burrows with Treptichnus, and the U-shaped burrow with Arenicolites. Furthermore, the spiral portion shows some similarities with Spirophycus and Spirodesmos. Interestingly, formation of these compound traces is connected with different ontogenetic stages of the producer. The winding and zigzag segments are produced, respectively, by Symplecta larvae and pupae for feeding purposes, whereas the U-shaped burrow is excavated during the end of pupal stage for protection until adulthood. In the fossil record, this incipient compound trace potentially may occur in lake-margin, fluvio-estuarine and overbank deposits, including levee, crevasse splay and pond deposits, forming part of the Scoyenia or the Mermia ichnofacies. Structures similar to those produced by modern diptera are known from freshwater ichnofaunas since the Devonian

Description of the male imago of Paracloeodes eurybranchus Lugo-Ortiz amp; McCafferty 1996 (Ephemeroptera: Baetidae).

Paracloeodes Day 1955 is represented in America by 22 species, sixteen of them are present in South America (Cruz et al. 2018b). The systematic of the genus is mainly based on nymphs (Nieto Salles 2006; Emmerich Nieto 2009; Lima et al. 2010; Cruz et al. 2017) but the association of both stages was recognized to improve the taxonomy of the genus (Cruz et al. 2018a, b). All species are known from the nymphal stage, eleven of them are known from male adults. Paracloeodes eurybranchus is known from nymphs and female adults from Argentina and Brazil. We here describe the male imago and give some additional data for the female imago. The nymphs were collected in small pools on the banks of Los Sauces river. The entire river has a sandy substrate. Along with them, nymphs of Americabaetis alphus Lugo-Ortiz McCafferty 1996 were also collected.

Растительность класса Loiseleurio procumbentis–Vaccinietea Eggler ex Schubert 1960 в восточноевропейских тундрах

Растительность класса Loiseleurio procumbentis–Vaccinietea Eggler ex Schubert 1960 в восточноевропейских тундрах

Rio Doce Acoustic Surveys of Fish Biomass and Aquatic Habitat

ABSTRACTFollowing the failure of the Fundão mine tailings dam in Brazil, approximately 32 million cubic meters of Fe ore tailings were released into the downstream riverine system. The postevent monitoring surveys implemented the use of noninvasive acoustic methods to improve the understanding of the fish biomass distribution patterns and aquatic habitat condition of the impacted reaches of the Rio Gualaxo do Norte, Rio do Carmo, and Rio Doce. The primary focus of the program was to collect hydroacoustic measurements of fish biomass, which was accompanied by sonar imaging of aquatic habitats using high‐resolution side scan and downward imaging sonar at each site visited. The biannual surveys began in April 2017 and were fundamentally a multiple control–impact design because before data (prior to the dam failure event) were not available. Up to 22 sites were visited for each survey, including reservoir and river sites. Results indicate similar levels of instream habitat between control and impact river and reservoir sites. Average volumetric biomass was not significantly different between impact sites and their corresponding controls in the August 2018 survey (latest to date). Preliminary temporal analysis of the biomass data set collected indicates that either stable or increasing levels of biomass are detected at tailings impacted sites within the Rio Doce. Integr Environ Assess Manag 2020;16:615–621. © 2020 Hydrobiology QLD Pty Ltd. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC)

Palaeoecological, sedimentological and stratigraphical insights into microbially induced sedimentary structures of the lower Cambrian successions of Iran

AbstractMicro‐organisms producing microbially induced sedimentary structures, particularly epibenthic cyanobacteria, are not facies‐dependent and could flourish in any environment if appropriate ecological conditions were provided. Hence, the changes in environmental parameters are the controlling factors on ecological tolerance of the producers. This study on the lower Cambrian successions of the Lalun Formation in Central Iran shows that paralic environments reacted differently to changes in parameters such as river and tide energy, palaeo‐topography, the rate of sediment supply and fluctuations in sea‐level, even though all were characterized by sandy substrates suitable for the development of microbially induced sedimentary structures. Therefore, the abundance and preservation of microbially induced sedimentary structures varied in the different paralic environments. From a sequence stratigraphic viewpoint, this study demonstrates that erosional discontinuities lacked the conditions required for the substrate stabilization by microbial communities. The distribution, size and type of microbially induced sedimentary structures within high frequency cycles generally follow the trends of changes in vertical facies stacking patterns. Within systems tracts, the pattern, morphological diversity and size of microbially induced sedimentary structures are not dependent on the type of systems tract, but on the type of depositional system developed such as delta, incised valley, coastal plain, estuaries and shoreline to shelf systems. Generally, estuarine and peritidal carbonates record an increase in the development of mat colonization during the transgressive systems tract, owing to decreased sedimentation rate as well as extended shallow water habitats. In contrast, the existence of microbially induced sedimentary structures depends on the pattern of shoreline shift in depositional systems developed during the highstand systems tract, such as open coast tidal flat and delta environments. If a shoreline regression was continuous (depositional trend and stacking pattern are a set of high frequency cycles), a greater increase in the aggradational component than the progradational component would cause intensified destructive processes hindering the development of microbial communities.

<p class="ZootaxaTitle"><strong>Preliminary report on Trichoptera from the headwaters of the Cuanavale, Cuito, Cuembo and Cuando Rivers in Angola</strong></p>

Trichoptera larvae and adults were collected as part of an overall assessment of aquatic macroinvertebrate diversity in the major headwater tributaries of the Okavango and Zambezi River basins in Angola. This report documents one of the National-Geographic-funded, Okavango-Wilderness-Project expeditions undertaken between October and November 2016. A total of 21 sites on the Cuanavale, Cuito, Cuando, and Cuembo Rivers and some of their tributaries were sampled. Biotopes sampled in source lakes, headwater streams, pools, and large rivers included mostly sandy substrates, aquatic emergent and submerged vegetation, marginal vegetation and (rarely) bedrock, stones, or gravel. Light trap collecting was possible at only seven sites. With both adults and larvae collected, at least 55 species in seven families (Philopotamidae, Dipseudopsidae, Ecnomidae, Hydropsychidae, Hydroptilidae, Leptoceridae, and Sericostomatidae) were recorded. The Leptoceridae were the most abundant family, represented by ten genera and 22 species. There are a number of unnamed species which will be described in a separate paper.

<strong>Trichoptera diversity in Icelandic springs</strong>

The aim of this study was to characterize the Trichoptera fauna of freshwater springs in Iceland and to relate distribution of caddis larvae to environmental properties of the springs. Out of a total of 48 springs sampled, Trichoptera larvae were found in only eleven. Larval densities were low, as was species diversity. Only three of the 12 species known to occur in Iceland were found: Apatania zonella, Limnephilus griseus, and Limnephilus affinis. The occurrence of A. zonella in springs in North-Iceland may suggest that springs might play a role as refugia for this species that is otherwise excluded from the area by larvae of the predatory caddis species Potamophylax cingulatus, which seems to be absent from spring habitats. Caddis larval abundance was higher in rheocrene springs and in springs with sandy substrate, and decreased with increasing water temperature. Presence or absence of Trichoptera larvae, on the other hand, was not associated with any of the environmental variables measured.

Environmental correlates of fine-scale juvenile steelhead trout (Oncorhynchus mykiss) habitat use and movement patterns in an intermittent estuary during drought

We used acoustic telemetry and environmental monitoring to elucidate preferred microhabitats of juvenile steelhead trout (Oncorhynchus mykiss) in a Central California intermittent estuary (IE) during historic drought. We collected over half a million fish locations in the Pescadero IE (San Mateo County, CA) across 15 weeks during an extended sandbar-closed period which permitted quantification of fine scale habitat use and movement patterns. Tagged juvenile steelhead expressed strong site fidelity, especially at night when core habitat area - defined as the 50% probability of being present in an area - contracted by over one order of magnitude. The rate of movement was slow overall (~0.4 to 0.6 lengths·s−1) and remained at baseline levels at night (~40 mm∙s−1). The daytime rate of movement generally tracked solar radiation levels and appeared to be moderated by water temperatures. Spikes in the rate of movement occurred during crepuscular periods and the maximum hourly rate of movement (138 mm∙s−1) was observed during the early study period from 10:00 to 11:00 when water temperatures were physiologically optimal (17–18 °C). Water quality worsened upstream when water temperatures exceeded 18 °C and dissolved oxygen concentrations declined below 7.0 mg·L−1. Fish tag detections at stationary receivers in the upper estuary declined linearly with deteriorating water quality conditions. Qualitative analysis of juvenile steelhead habitat utilization indicated a strong preference for two microhabitat features in the estuary during the study; both were shallow (~1.5 m), wind-protected, and possessed cover and sandy substrates that occurred within the fresh or near fresh epilimnion where lagoon water quality was best and benthic prey was likely most abundant. Upstream movement occurred in late fall for over half of the tagged cohort, which likely enhances population resiliency by allowing these fish to escape lethal water quality conditions coincident with the transition from closed to open estuary in late fall. Climate projections for California’s Central Coast predict an increase in extreme dry events and the information presented here can help natural resource managers prepare for the future, such as the critical need to promote development of a sufficiently oxygenated epilimnion during extended sandbar-closed ecosystem states.

Habitat characteristics and size structure in a population of an endangered lamprey, Lethenteron sp. N, in an urbanized area of Japan

For conservation of a lamprey population in an urbanized area, basic properties including taxonomic attribution, habitat characteristics and spatial distribution were investigated. Sequencing analysis of mitochondrial genes suggested that the population belongs to Lethenteron sp. N. The abundance and size distribution of the population varied temporally and spatially. Spawning activity was observed only in the uppermost reach. Although a drop structure at the downstream may prevent the movement of individuals, the presence of many sources of spring water and sandy substrate in the study stream suggested that the local condition of habitat was suitable for this species.

Invasive zebra mussel (Dreissena polymorpha) threatens an exceptionally large population of the depressed river mussel (Pseudanodonta complanata) in a postglacial lake.

Freshwater mussels are in decline worldwide, with the depressed river mussel Pseudanodonta complanata being one of the rarest and most endangered species in Europe. Invasive mussels are suspected to be an important factor of decline, but there is little information on their interaction with native species.This study analyzed densities, depth distribution, and individual sizes and weights in one of the largest known populations of P. complanata in Europe in relation to the co‐occurring invasive zebra mussel Dreissena polymorpha and other mussel species, using a systematic transect analysis. Pseudanodonta complanata was the dominant unionid species in Lake Siecino reaching densities of up to 26 ind/m2, with half of the specimens found at a water depth of 2.0–4.0 m. Densities were highest on sandy substrates in areas of underwater currents. In contrast, 67% of native Unio tumidus were found at depths < 1 m, indicating different habitat preference.In the study area, 91% of P. complanata, 92% of U. tumidus, and all Anodonta individuals were fouled by D. polymorpha. The dreissenid:unionid mass ratio (mean ± SD; maximum) was 0.43 ± 0.56; 4.22 and 0.86 ± 1.87; 8.76 in P. complanata and U. tumidus, respectively. Pseudanodonta complanata fouled with D. polymorpha were impaired in their anchoring capability and had shell deformations potentially affecting shell closing and filtration activity. Fouling intensity was negatively correlated with unionid density, potentially leading to accelerated population declines.The observed adverse effects of invasive zebra mussels on the depressed river mussel and the difficulties in eradicating established populations of invasive mussels suggest that D. polymorpha should be considered a serious threat to P. complanata. Therefore, the further spread of zebra mussels into habitats with native unionids needs to be avoided by all means.

Paleoenvironmental significance of microbial mat-related structures and ichnofaunas in an Ordovician mixed-energy estuary, Áspero Formation of Santa Victoria Group, northwestern Argentina

ABSTRACTThe study on a unique set of outstandingly preserved sedimentary surface textures (SSTs) found in the late Tremadocian Áspero Formation of northwestern Argentina, coupled with the sedimentological and ichnological analysis, indicate that they were formed in the intertidal to supratidal setting of a mixed-energy estuary recording storm and tide sedimentation. We recognize seven types of SSTs: probably biotic microbial mat-related SSTs (Kinneyia, elephant skin, exfoliating sandy laminae), abiotic SSTs (elliptical scours and convex parallel ridges type I “wrinkle marks” sensuAllen 1985), and problematic (convex parallel ridges type II and dot matrix texture). Elliptical scours and convex parallel ridges type I show features which indicate reworking of a cohesive sandy substrate in an intertidal or supratidal setting. Abundance of biotic SSTs with specific associated trace fossils reflect matground development and mat-grazing ichnofaunas, indicating the suppression of intense, penetrative bioturbation due to intense physicochemical stress. The “dot matrix” texture, described here for the first time, consists of a regular horizontal network of millimeter-scale pits; it appears associated with exfoliating sandy laminae, probably reflecting a mat-related origin. Three facies associations are defined through paleoenvironmental analysis. Facies association 1 is dominated by high-energy sandy and bioclastic storm deposits with tidal flat facies, and corresponds to the outer bay of a mixed-energy estuary; highly impoverished Cruziana assemblages and distal expressions of the Skolithos Ichnofacies reflect high energy and sedimentation rate. Facies association 2 shows tidal-channel and tidal-flat facies with subordinated storm deposits, representing the middle bay; impoverished Cruziana assemblages dominated by simple facies-crossing structures, with high-density monogeneric opportunistic suites, evidence physicochemical stress associated with subaerial exposure, frequent episodic deposition, high water turbidity, and/or brackish water conditions in these relatively sheltered tidal flats. Facies association 3 is formed by interdistributary-bay deposits with intercalation of channel-fill deposits in the upper part, and represents the river-dominated bay-head delta; low degrees of bioturbation in fine-grained facies indicate brackish- to fresh-water conditions. SSTs are found in tidal flat facies of facies association 2; they indicate an intertidal to supratidal environment subject to localized conditions of intense physicochemical stress. The paleoenvironmental interpretation of SSTs converges with the one performed through sedimentological and ichnological analysis, producing a robust and more detailed paleoenvironmental model for the Áspero Formation. Our study highlights the use of SSTs as a tool for supporting and refining paleoenvironmental analysis.

Wheat Straw Biochar and NPK Fertilization Efficiency in Sandy Soil Reclamation

Intensive land use including cultivation may result in soil degradation. Restoring natural conditions or utility values called reclamation usually requires prior improvement of soil properties by using fertilizers or soil amendments. Special attention is paid to biochar, as it can improve soil physical and chemical properties. Therefore, amendment is potentially useful for preparation of degraded soil for future vegetation. In pot experiments, we studied the effect of wheat straw biochar (5% v/w) (soil with biochar (S + BC)), two rates of mineral fertilizer (no fertilizer as a control set (SC) and single initial dose of fertilizer (S + NPK)), and combination of biochar and fertilizer (S + B C + NPK) on sandy soil properties and grass growth. Biochar significantly increased soil pH, total organic carbon content (TOC), and volumetric water content (VWC, +24% after one week of measurements). However, dry mass of grass shoots was lower in S + BC than in SC (−38%). It was also observed that, in fertilizer, applied sets high concentrations of salts caused crust formation, surface cracking, and overdrying. Considering the results, biochar may be useful for increasing sandy substrate fertility, providing proper conditions for revegetation during reclamation.

Demersal amphipod migrations: spatial patterns in marine shallow waters

AbstractThe nocturnal displacement to the water column of species hiding in the substrate during the day (so-called demersal migration) is a widespread phenomenon in coastal habitats. However, despite the relevance of these migrations to coastal ecosystem functioning, most of their ecological aspects are poorly understood. We aim to characterize spatial distribution patterns of demersal amphipods by comparing samples collected by light traps deployed both at rocky and nearby sandy areas. Dispersal abilities of such species were explored by considering two spatial scales of separation between rocky and sandy substrates: (1) &lt;100 m and (2) &gt;1 km. A total of &gt;45,000 amphipod specimens were collected in the water column during the whole study, belonging to 50 species. The numerically dominant species were Guernea coalita, Bathyporeia cf. elegans, Perioculodes longimanus and Nototropis swammerdamei. The present study highlights the relevance of substrate type and study location on coastal demersal amphipod migrations. Amphipod assemblages were significantly different in the water column above rocky and sandy bottoms, even at a small spatial scale. Species emerging from rocky bottoms tend to remain in the proximity of this habitat; they showed lower abundances in sandy areas located nearby and almost none of them reached distant sandy areas. In contrast, migrant species commonly found on sediment during the day were collected at higher abundances in light traps deployed above rocky bottoms. Although several factors (e.g. food availability, predation pressure) are proposed to explain these patterns, the purpose of this horizontal migration remains unknown.

The soil moisture regime of charcoal-enriched land use legacy sites

The stratigraphy and properties of soils can be significantly altered by past land use, even in areas that have been continuously used for forestry. An example of such a pedological legacy of past forest use is the soils associated with relict charcoal hearths (RCHs). The physical properties and moisture regime of RCH soils and their ecological implications have hardly been studied, although RCHs are widespread in many forest areas and might be used as model sites to study long-term effects of soil amendment with biochar. The objective of our study was to characterize the soil moisture regime and hydraulic properties of RCH soils through comparison to reference forest soils on sandy substrates in the northeastern German lowlands. RCH and reference soils were studied in woodlands around the historic iron works in Peitz (Brandenburg, Germany), combining laboratory analyses of bulk density, pore size distribution, and saturated hydraulic conductivity with sensor-based monitoring of soil moisture contents and matric potentials. The laboratory analyses reveal a low bulk density and high porosity of the RCH substrates, which is mainly related to larger volumes of coarse and fine pores. Soil moisture monitoring shows higher water contents in RCH soils under relatively wet conditions and lower water contents under dry conditions, as well as strong hysteresis effects, especially after dry periods. The results therefore affirm that the legacies of charcoal production increase spatial and temporal variations in soil moisture, which in turn can cause increased variability in ecological site conditions in charcoal production areas. They furthermore reveal that the high porosity of charcoal-enriched substrates is not necessarily associated with higher water retention and plant-available water contents, and that the pore size distribution and water retention in RCHs differ from those characteristically found for biochar-amended soils.

Variation of benthic macroinvertebrate communities in streams of three landscapes of South Brazilian grasslands

Introduction: Aquatic ecosystems in southern Brazil are presently under great environmental pressure. Changes in land use result in negative impacts on the ecosystem, affecting the functioning of stream communities. Objective: To compare the benthic macroinvertebrate community richness, abundances and compositions in streams of three South Brazilian grassland landscapes and correlate community patterns with environmental and spatial variables. Methods: Fifteen streams along riparian forests were selected in three landscapes (mean geographical distance of 285.1 km) inserted in the Paraná and Uruguai river basins. Of the three landscapes, two are inserted in conservation units (State Park of Guartelá and Palmas Wildlife Refuge). Invertebrates were collected in 20 kick net points along 150 m of the streams between June and November 2015. Invertebrates were sorted in the laboratory with three sieves and were identified to the lowest taxonomic level possible. The taxa were classified in functional feeding groups of shredders/detritivores, predators, scrapers, collectors/filters and gatherers/collectors. For each stream, we measured the environmental variables width and velocity, pH, dissolved oxygen, and temperature; and the relative cover of forest, grassland, plantation and silviculture in the catchments. Results: We found a total of 1 058 individuals, divided in 53 morphospecies and 34 families. Lower abundance of benthic macroinvertebrates was found in the northernmost landscape with higher temperature, and forest in the catchment. These streams were described mainly by predator groups, while streams inserted in the other two landscapes showed a more diverse guild composition of shredders/detritivores, gatherers/collectors, collectors/filterers, and scrapers. Geographical distance was the main factor influencing differences in community compositions among landscapes. Conclusions: Lower abundance of the northernmost landscape may be explained by (i) the low habitat heterogeneity due to dominance of sandy substrates, and by (ii) the anthropogenic land use of agriculture and extensive cattle breeding in the region that is ongoing and started before the creation of the conservation unit. Additionally, composition of macroinvertebrates may be correlated with environmental differences among landscapes that, in turn, are related to the geographical distance. Therefore, macroinvertebrate community responses may reflect different biota biogeographical histories that can also be associated with historical land use practices.

Conspecific brood parasitism in an upland-nesting bird: cues parasites use to select a nest

Among birds exhibiting conspecific brood parasitism (CBP), parasites demonstrate a variety of intriguing tactics for selecting a host nest, including preference for safe nests (i.e., avoiding nests depredated during the previous season). Brood parasites of birds that do not reuse nest sites, however, are limited to nest-site information available to them during the current breeding season. This study explores cues used by brood parasites in a population of red-breasted mergansers nesting in upland vegetation and sandy substrate that prohibits reuse of nest sites in consecutive years. Nest-site and host traits were measured for 33 parasitized and 23 non-parasitized nests. There was no association between CBP and nest-site traits potentially providing cues about nest safety from avian predators (concealment and density of nesting larids), likely due to very low rates of egg predation. Distance to shore for parasitized nests was slightly greater than for unparasitized nests. Parasites did not select nests in relation to host age, mass, date of nest initiation, or stage of nesting (laying or incubation). Artificial nests were used to simulate natural nests without a host and to assess whether host presence serves as a cue for parasites. The proportion of natural nests receiving ≥ 1 foreign egg (60% of 15 nests) was thrice that for artificial nests (21% of 14 nests). Some aspect of host presence may therefore be an important, but not necessary, cue for brood parasites targeting nests that are heavily concealed in uplands. Whenever brood parasitism is a well-developed component of reproduction, selection is expected to favor brood parasites that make use of environmental or social information allowing them to discriminate among host nests and maximize reproductive success. We assessed cues used by brood parasites in ground-nesting red-breasted mergansers for which conspecific brood parasitism (CBP) is common, and nests are well concealed in upland vegetation. Observations at parasitized and unparasitized nests revealed that nest-site safety and visibility from habitat edges are not central to laying decisions by parasites in this population. Brood parasites, however, were considerably more likely to lay their eggs in natural nests with a host than in artificial nests without a host, suggesting that some aspect of host presence is important in the nest-site selection process for parasites. The ability of brood parasites to discriminate among nests based on host presence is expected to affect parasite success because individuals can avoid nests in which their eggs are doomed to fail (e.g., abandoned nests).