Photoautotrophs and macroinvertebrate trophic relations in calcareous semiarid streams: The role of Cyanobacteria.

Photoautotrophs and macroinvertebrate trophic relations in Mediterranean streams, especially from semiarid areas, are still poorly known, as is the role of Cyanobacteria, which is the most frequently dominant photoautotroph. To investigate the role of Cyanobacteria as a food resource in these systems, the fatty acid composition of primary and secondary producers was investigated in two streams on a semiarid climatic gradient between 200 and 500 mm of rainfall in SE Spain. Fatty acid composition of photoautotrophs and macroinvertebrates differed among streams in summer and among seasons in each stream. Fatty acid fingerprints show that macroinvertebrates usually fed on the dominant photoautotroph assemblage and that Cyanobacteria represent the main food for all the feeding groups in the Alhárabe stream in winter although filamentous green algae were preferred in summer. Only scrapers consuming Chlorophyta displayed a selective feeding behaviour. The results show the importance of cyanobacteria as food for all collected macroinvertebrates in winter in some semiarid streams and confirm that fatty acids can be used as temporal and spatial markers in fluvial systems.

Microbiomes in Suspended Soils of Vascular Epiphytes Differ from Terrestrial Soil Microbiomes and from Each Other.

Microbial biodiversity parameters for tropical rainforests remain poorly understood. Whilst the soil microbiome accounts up to 95% of the total diversity of microorganisms in terrestrial ecosystems, the microbiome of suspended soils formed by vascular epiphytes remains completely unexplored. Samples of ground and suspended soils were collected in Cat Tien National Park, southern Vietnam. DNA extraction and sequencing were performed, and libraries of 16s rDNA gene sequences were analyzed. Alpha diversity indices of the microorganisms were the highest in the forest ground soil. In general, the microbiological diversity of all the soil types was found to be similar at the phylum level. Taxonomic composition of the bacterial communities in the suspended soils of plants from the same species are not closer than the taxonomic compositions of the communities in the suspended soils of different plant species. However, the beta diversity analysis revealed significant differences in the movement of mineral elements in terrestrial versus suspended soils. Our data showed that the suspended soils associated with vascular epiphytes were a depository of unique microbiological biodiversity. A contributing factor was the presence of large amounts of organic matter in the suspended soils-deposits collected by the epiphytes-which would have been degraded by termites if it had reached the ground. Further, the nutrient content of the suspended soils was prime for soil respiration activity and taxonomic microbial community biodiversity.

First data on the bionomics of Leptochilus (Euleptochilus) limbiferus (Morawitz, 1867) (Hymenoptera: Vespidae: Eumeninae), with taxonomic notes and new records.

Nesting of Leptochilus limbiferus (Morawitz, 1867) was observed in the Krasnodar Territory, Russia. Twelve nests were studied; all of them were located in empty shells of a terrestrial snail species, Xeropicta derbentina (Krynicki). The building material used by the wasps was pellets of dry soil and gravel particles, as well as shell bits, and sometimes also tiny shells. Females hunted for caterpillars of a gelechiid moth Syncopacma coronillella (Treitschke) and two unidentified species. Imagoes of L. limbiferus were observed feeding on nectar at flowers of five plant species in five families. Males were also observed patrolling the nesting site and sleeping inside a shell of X. derbentina. Nests were invaded by ants and an anthracine fly. Nesting activity and structure of the nests and cocoons are described in detail. The species is univoltine; hibernation occurs at the prepupa stage. The present contribution is the first detailed report on the bionomics of the subgenus Euleptochilus Blüthgen, 1943. Nesting of Old World species of Leptochilus de Saussure, 1853 is discussed with special reference to use of gravel as building material in two phylogenetic lineages: Leptochilus and unrelated genus Alastor Lepeletier de Saint-Fargeau, 1841. The distribution of L. limbiferus is summarized; particularly, the species is reported from Montenegro and Azerbaijan for the first time. At the same time, its previous records from Armenia were found to be based on a misidentification of Leptochilus (Euleptochilus) duplicatus (Klug, 1835) (new for Armenia and the Caucasus as a whole). Leptochilus limbiferus anatolicus Blüthgen, 1955 and L. limbiferus achaeus Gusenleitner, 1970 are treated as synonyms of L. limbiferus s. str. (new synonymies). The lectotype of Odynerus limbiferus Morawitz, 1867 is designated. A key to subgenera of Leptochilus is provided.

They are here to stay: the biology and ecology of lionfish (Pterois miles) in the Mediterranean Sea.

The lionfish, Pterois miles, is one of the most recent Lessepsian immigrants into the Mediterranean Sea, and it poses a serious threat to marine ecosystems in the region. This study assesses the basic biology and ecology of lionfish in the Mediterranean, examining morphometrics, reproduction and diet as well as population structure and distribution. The population density of lionfish has increased dramatically in Cyprus since the first sighting in late 2012; by 2018 aggregations of up to 70 lionfish were found on rocky grounds with complex reefs and artificial reefs in depths of 0-50 m. Lionfish in Cyprus become mature within a year, and adults are capable of spawning year-round, with peak spawning in summer when the sea-surface temperature reaches 28.4°C. The Cypriot lionfish grow faster and bigger than in their native range, and females are more common than males. Lionfish are generalist predators in these waters, as also found in their native range, consuming a range of teleost and crustacean prey, some of which are of high economic value (e.g., Spicara smaris and Sparisoma cretense) or have an important role in local trophic webs (e.g., Chromis chromis). Overall, the reproductive patterns, the presence of juveniles and adults throughout the year, the rapid growth rates and the generalist diet indicate that lionfish are thriving and are now already well established in the region and could potentially become the serious nuisance that they are in their temperate and tropical western Atlantic-invasive range.

Trophic transfer, biomagnification and risk assessments of four common heavy metals in the food web of Laizhou Bay, the Bohai Sea.

This study investigated the trophic transfer of four common toxic metals (Cd, Cr, Cu and Hg) in the food web and assessed their potential ecological risks in Laizhou Bay, a spawning area for fishery populations in the Bohai Sea, North China. Based on the predation relations of 43 species that were representatives of the main trophic levels (TLs), a simplified food web was constructed using stomach content analysis and stable nitrogen isotope ratio (δ15N) analysis. Using copepods as the baseline species (TL = 2.00), the TLs of the organisms ranged from 1.96 (Polychaeta) to 4.47 (Japanese flounder) and showed the following ranking order: predatory pelagic or demersal fish > medium demersal fish > crustacean, cephalopod, small pelagic or demersal fish > zooplankton and Polychaeta. The metals showed different trophic transfer behaviors in the food web. Hg and Cr tended to be efficiently biomagnified between TLs, along the main food chains and in the food web. Cu biodiluted significantly with increasing TLs, while Cd showed no biomagnification or biodilution trends in the food web. At low or moderate levels of Cd and Hg, potential ecological risks were detected in the water and sediments at only a few sites, indicating their overall low ecological risks in the environment. The metals in the important fishery species (four top predatory fish, two cephalopods and eight crustaceans) were below the permissible limits, except for Cd in octopus and paddle crab, which reached or exceeded the most restrictive criteria. Based on the provisional tolerable weekly intake (PTWI) criteria, the safe weekly human consumption levels by humans of the predatory fish, cephalopods and crustaceans were species-specific (0.20-4.44 kg) and should be cautiously assessed.

Trophic network of aquatic macroinvertebrates along an altitudinal gradient in a Neotropical mountain river

ABSTRACT Studies of trophic networks and the evaluation of processes that occur along altitudinal gradients in river systems are of great importance because they allow an understanding of energy flow dynamics and provide scientific tools for the planning and management of river ecosystems. This research describes the trophic network of aquatic macroinvertebrates along an altitudinal gradient of the Gaira River, a mountain Neotropical watercourse located in the Sierra Nevada de Santa Marta in northern Colombia. The organisms were collected in the upper, middle and lower reaches of the river during the rainy and dry seasons (between 2010 and 2013). Trophic relationships were evaluated through gut content analysis. The contents were determined and quantified using photographs and expert review, and a binary consumption matrix was used to determine the characteristics of the trophic network. We characterized the diet composition at each site for each season using discriminant analysis. Trophic networks during the dry seasons showed higher trophic species richness and linkage density, and the predominance of coarse particulate organic matter (CPOM) and fine particulate organic matter (FPOM) in the high and medium sections of the river. During the dry seasons the diets had a lower number of basal species, but in the low river section there was a high percentage of fungi and microalgae. During the rainy seasons, no patterns were observed for the percentage of resources. Results indicated a direct relation between periods of hydrologic stability and an increase of CPOM during dry seasons and an increase of resource diversity consumed by macroinvertebrates at all sites during the rainy season, showing that changes in trophic networks of the Gaira River were more important during seasonal periods than along the altitudinal gradient.

Effects of dietary exposure to herbicide and of the nutritive quality of contaminated food on the reproductive output of Daphnia magna.

Risk assessment of pesticides has been based on direct toxic effects on aquatic organisms. Indirect effects data are taken into account but with limitations, as it is frequently difficult to predict their real impacts in the ecosystems. In this context the main aim of this work was to assess how the exposure to the herbicide pendimethalin (Prowl(®)), under environmentally relevant concentrations, may compromise the nutritional composition of food for a relevant group of primary consumers of freshwater food webs-the daphnids, thus affecting their reproduction performance and subsequently the long-term sustainability of active populations of this grazer. Therefore, Daphnia magna individuals were chronically exposed in a clean medium to a control diet (NCF - i.e., non-contaminated green algae Raphidocelis subcapitata) and to a contaminated diet (CF - i.e., the same monoalgal culture grown in a medium enriched with pendimethalin in a concentration equivalent to the EC20 for growth inhibition of algae), during which reproductive endpoints were assessed. The algae were analysed for protein, carbohydrate and fatty acid content. The chemical composition of R. subcapitata in the CF revealed a slight decrease on total fatty acid levels, with a particular decrease of essential ω9 monounsaturated fatty acids. In contrast, the protein content was high in the CF. D. magna exposed to CF experienced a 16% reduction in reproduction, measured as the total number of offspring produced per female. Additionally, an internal pendimethalin body burden of 4.226µgg(-1) was accumulated by daphnids fed with CF. Hence, although it is difficult to discriminate the contribution of the pesticide (as a toxic agent transferred through the food web) from that of the food with a poor quality-compromised by the same pesticide, there are no doubts that, under environmentally relevant concentrations of pesticides, both pathways may compromise the populations of freshwater grazers in the long term, with consequences in the control of the primary productivity of these systems.

Experimental Evidence that Fungi are Dominant Microbes in Carbon Content and Growth Response to Added Soluble Organic Carbon in Moss-rich Tundra Soil.

Global warming significantly affects Arctic tundra, including permafrost thaw and soluble C release that may differentially affect tundra microbial growth. Using laboratory experiments, we report some of the first evidence for the effects of soluble glucose-C enrichment on tundra soil prokaryotes (bacteria and archaea) and fungi, with comparisons to microbial eukaryotes. Fungal increase in C-biomass was equivalent to 10% (w/w) of the added glucose-C, and for prokaryote biomass 2% (w/w), the latter comparable to prior published results. The C-gain after 14 d was 1.3 mg/g soil for fungi, and ~200 µg/g for prokaryotes.

Cambios en las comunidades de peces de los arrecifes coralinos del Archipiélago Sabana-Camagüey, Cuba

Changes in fish communities of coral reefs at Sabana-Camagüey Archipelago, Cuba. A comparison of fish community structure in the Sabana-Camagüey Archipelago (1988-1989 and 2000) using visual census surveys (eight belt transects 2x50 m in each site) suggests a notable decrease on species richness, and a two thirds reduction in fish density and biomass on coral reefs. This decrease in fish populations may be related to the alarming decrease of scleractinian coral cover, and an enormous proliferation of algae, which currently covers 70-80% of the hard substrate, impeding the recovery of corals and other benthic organisms. High coral mortalities occurred between the study periods, which correlate with the high temperatures caused by the ENSO events of 1995, 1997 and 1998. These events caused massive bleaching of corals and subsequent algae overgrowth. Evidence of nutrient enrichment from the inner lagoons and overfishing are also present. Collectively, these effects have provoked a marked degradation of reef habitats. These changes appear to have affected the availability of refuges and food for fishes, and may be constraining individual growth potential and population size. Rev. Biol. Trop. 55 (2): 537-547. Epub 2007 June, 29.

Al comparar la estructura de las comunidades de peces en los arrecifes del Archipiélago Sabana-Camagüey entre 1988-89 y el año 2000, mediante iguales censos visuales (ocho transeptos lineales de 2x50 m en cada estación), se observó una notable disminución de la riqueza de especies y una reducción en dos tercios de la densidad y biomasa de peces. Tal disminución de las poblaciones de peces parece estar relacionada con la alarmante disminución de la cobertura de corales escleractínios y una gran proliferación de algas, las cuales actualmente cubren 7080% del sustrato duro, impidiendo la recuperación de los corales y otros organismos bénticos. Grandes mortalidades de corales ocurrieron entre los dos periodos de estudio, lo cual parece ser consecuencia de las altas temperaturas provocadas por los eventos ENOS de 1995, 1997 y 1998. Estos fenómenos climáticos provocaron el blanqueamiento masivo de los corales y como consecuencia se produjo una gran proliferación de las algas. Asimismo en el período entre ambos muestreos ocurrió el enriquecimiento de nutrientes desde las lagunas interiores y la sobreexplotación de los recursos pesqueros. El conjunto de estos factores provocaron una marcada degradación del hábitat en los arrecifes. Tales cambios parecen haber afectado la disponibilidad de refugios y la alimentación para los peces, limitando el crecimiento individual y el tamaño de las poblaciones.

Estructura de la comunidad de moluscos y relaciones tróficas en el litoral rocoso del estado Sucre, Venezuela / Structure of the mollusk community and trophic relationships in the rocky coast of Sucre state, Venezuela

Mollusc community structure and trophic relations in the rochy littoral zone in Sucre State, Venezuela. We analyzed the structure of a mollusc community and its component trophic relations at six localities within a rocky littoral zone, in Sucre State, Venezuela, including areas that are both exposed to, and protected from, wave energy. Sampling was carried out from March 2003 to Febreuary 2004 period, in an area subdivided in to supralittoral, littoral and sublittoral zones. Samples were collected using hand-held spoons within 0.25 m² quadrats along transects sited perpendicular to the coast line transects. Collected organisms were preserved in 10% formalin for subsequent taxonomic classification. Specific richness and constance were determined, and the four trophic categories of herbivore, suspendivore, carnivore and herbivore-suspendivore were established. Overall 14 581 individual specimens were collected that represented 68 species, 31 families and 9 orders, in the classes Gasteropoda (n=39), Bivalvia (n=23) and Polyplacophora (nn=6). Suspension feeders were the dominant trophic category (49%), followed by carnivores (337%), herbivores (13%) and herbivores-suspension feeders (11%). Herbivores and suspension feeders were dominant in the protected area, while carnivores and suspension feeders were dominant in the exposed area. Data indicate that mollusc distribution and intergroupal trophic relations are controlled by both morphological features and substrate composition. Rev. Biol. Trop. 54 (Suppl. 3): 121-130. Epub 2007 Jan. 15.

Se analizó la estructura de la comunidad de moluscos y sus relaciones tróficas en seis localidades del litoral rocoso con diferentes grados de exposición al oleaje (área expuesta y área protegida), en el Estado Sucre, Venezuela. El muestreo se llevó a cabo durante el período de marzo 2003 a febrero 2004. La recolección del material biológico se realizó de forma manual con ayuda de una espátula, dentro de una cuadrícula de 0.25 m², estableciéndose tres zonas: supra, medio e infralitoral. Los organismos fueron preservados en frascos con formalina al 10% para su posterior análisis. En el laboratorio fueron identificados, contados, y pesados en una balanza de 0.001g de precisión. Se determinó la abundancia total de especies, biomasa, constancia específica y por medio de una revisión bibliográfica se le asignó a cada especie su categoría trófica, clasificándolos en: herbívoros, filtradores, carnívoros y herbívoros -filtradores. Se obtuvo un total de 14 581 individuos (6 397.945 g) representado por 68 especies correspondientes a las clases Gastropoda (39), Bivalvia (23) y Polyplacophora (6); contenidas en nueve órdenes y 31 familias. Los herbívoros fueron el grupo dominante (49%), seguido por filtradores (37%), carnívoros (13 %) y herbívoros-filtradores (1%). Las especies herbívoras y herbívoras-filtradoras dominaron en el área protegida, mientras que en el área expuesta, fueron las carnívoras y filtradoras. Las especies constantes en las seis localidades durante el período de estudio fueron Planaxis nucleus, Mitrella ocellata, M. nycteis, Littorina interrupta, Tegula fasciata, Acmaea leucopleura, Ostrea equestris y Chiton squamosus. La distribución de los moluscos y los diferentes grupos tróficos, pueden estar controlados por adaptaciones morfológicas, así como el nivel de exposición al oleaje y composición del sustrato.

Primary producers sustaining macro-invertebrate communities in intertidal mangrove forests.

In contrast to the large number of studies on the trophic significance of mangrove primary production to the aquatic foodweb, there have been few attempts to provide an overview of the relative importance of different primary carbon sources to invertebrates in the intertidal mangrove habitats. We determined carbon and nitrogen stable isotope ratios (δ13C, δ15N) in sediments, primary producers, and 22 invertebrate species from an intertidal mangrove forest located along the southeast coast of India in order to determine the contribution of mangrove leaf litter and other carbon sources to the invertebrate community. Organic matter in sediments under the mangrove vegetation was characterized by relatively high δ13C values and low C:N ratios, indicating that mangrove-derived organic matter was not the principal source and that imported phytodetritus from the mangrove creeks and adjacent bay significantly contributed to the sediment organic matter pool. Invertebrates were found to display a wide range of δ13C values, most being 3-11‰ enriched relative to the average mangrove leaf signal. The pulmonate gastropod Onchidium sp. showed unusually low δ15N values (-5.6±0.9‰), but further work is needed to adequately explain these data. A compilation of stable isotope data from various sources indicates that significant assimilation of mangrove-derived carbon is only detectable in a limited number of species, and suggests that local and imported algal sources are a major source of carbon for benthic invertebrate communities in intertidal mangrove forests. These results provide new insights into carbon utilization patterns in vegetated tropical intertidal habitats and show a striking similarity with results from temperate salt marsh ecosystems where local plant production has often been found to contribute little to intertidal foodwebs.