Responses of aquatic communities to seasonal changes in a non-perennial river of the Brazilian semiarid region

Response of a Mediterranean semiarid community to changing patterns of water supply

Cerambycidae is one of the largest families of Coleoptera, with approximately 38,000 species described. Knowledge of Cerambycidae fauna in Brazil has increased in the last 50 years, but some regions, such as the Brazilian semi-arid region, remain relatively unexplored. An updated checklist of Cerambycidae from that region, based on previously published works, checklists, and catalogs, and the study of 331 specimens of 72 species, 58 genera, 26 tribes, and three subfamilies deposited in the collection of the Zoology Museum of the Universidade Estadual de Feira de Santana is provided. This list has 633 species, 303 genera, 58 tribes, of four subfamilies of Cerambycidae from 75 municipalities in nine states in the Brazilian semi-arid region. A map illustrating the distribution of the Cerambycidae species in the semi-arid region is also provided. Four new species are described: Eburodacrys boteroi sp. nov. and Coccoderus costae sp. nov. (Cerambycinae); and Aerenicopsis joseferreirai sp. nov. and Pseudomecas mourai sp. nov. (Lamiinae). The new species are included in an identification key to the respective genus. Furthermore, Antodice kyra Martins & Galileo, 1998 is new record from the Bahia State; Chevrolatella tripunctata (Chevrolat, 1862) is a new record to Brazilian semi-arid region; Colobothea rubroornata Zajciw, 1962 is a new record from Bahia State and Brazilian semi-arid region, and Odontocera bilobata Zajciw, 1965 is a new record from the Bahia State and Brazilian semi-arid region. It is evident that some regions in the Brazilian semi-arid region are poorly sampled and new inventory studies must be carried out.

SummaryTo quantify the major environmental drivers of stream bacterial population dynamics, we modelled temporal differences in stream bacterial communities to quantify community shifts, including those relating to cyclical seasonal variation and more sporadic bloom events. We applied Illumina MiSeq 16S rRNA bacterial gene sequencing of 892 stream biofilm samples, collected monthly for 36‐months from six streams. The streams were located a maximum of 118 km apart and drained three different catchment types (forest, urban and rural land uses). We identified repeatable seasonal patterns among bacterial taxa, allowing their separation into three ecological groupings, those following linear, bloom/trough and repeated, seasonal trends. Various physicochemical parameters (light, water and air temperature, pH, dissolved oxygen, nutrients) were linked to temporal community changes. Our models indicate that bloom events and seasonal episodes modify biofilm bacterial populations, suggesting that distinct microbial taxa thrive during these events including non‐cyanobacterial community members. These models could aid in determining how temporal environmental changes affect community assembly and guide the selection of appropriate statistical models to capture future community responses to environmental change.

Seasonal environmental variation is a leading driver of microbial planktonic community assembly and interactions. However, departures from usual seasonal trends are often reported. To understand the role of local stressors in modifying seasonal succession, we sampled fortnightly, throughout three seasons, five nearby shallow soda lakes exposed to identical seasonal and meteorological changes. We characterised their microeukaryotic and bacterial communities by amplicon sequencing of the 16S and 18S rRNA gene, respectively. Biological interactions were inferred by analyses of synchronous and time-shifted interaction networks, and the keystone taxa of the communities were topologically identified. The lakes showed similar succession patterns during the study period with spring being characterised by the relevance of trophic interactions and a certain level of community stability followed by a more dynamic and variable summer-autumn period. Adaptation to general seasonal changes happened through shared core microbiome of the lakes. Stochastic events such as desiccation disrupted common network attributes and introduced shifts from the prevalent seasonal trajectory. Our results demonstrated that, despite being extreme and highly variable habitats, shallow soda lakes exhibit certain similarities in the seasonality of their planktonic communities, yet local stressors such as droughts instigate deviations from prevalent trends to a greater extent for microeukaryotic than for bacterial communities.

BackgroundHunting has been an important cultural and subsistence activity for the survival of the human population. In the Brazilian semiarid region (Caatinga), the extreme seasonal changes and socioeconomic conditions have made local people dependent on the natural resources available, including wildlife. Although hunting with dogs can result in higher efficiency for hunters, it can also have implications for game species conservation.MethodsUsing an ethnozoological approach (semi-structured questionnaires, free interviews, informal conversations, and free listing technique), this study aimed to analyze the patterns of hunting with dogs activities in a semiarid region of northeastern Brazil by characterizing hunters’ and hunting dogs’ profiles, investigating target and nontarget prey species, hunters’ practices, motivations, and perceptions regarding the efficiency of hunting with dogs.ResultsWe found that hunters that use dog assistance were mostly men, of different ages, with an occupation in agriculture, receiving less than a minimum wage, and with a low level of formal education. Hunters use two or more mixed-breed dogs with no clear preference regarding dogs’ sex. The motivations for hunting with dogs included mainly food, sport, and trade. Hunters cited twenty species captured by dogs without distinction between prey’s sex and age (14 mammals, 4 birds, and 2 reptiles). Only six of these were mentioned as being target prey when hunting with dogs. From nontarget species, eight carnivores are usually left at the site of kill, as they have no use to the hunters. Hunters perceived that hunting with dogs could be three times more efficient than hunting without dogs.ConclusionOverall, hunting with dogs represents a complex set of local variables, including characteristics of dogs and prey species, hunters’ motivations, and practices that should be considered according to each particular situation. Considering the human dependence on natural resources in the semiarid region, hunters should be included in wildlife management debates to mitigate the threat to game species while allowing sustainable hunting practices.

Moisture, temperature and respiration of two soil classes under pasture and tropical dry forest in the semiarid Brazilian region

Stressors of various nature impact fish reproduction from the physiological to the behavioural levels. Seasonal changes such as drought and pluvial (rainfall) variations have a profound effect on reproduction of semiarid tropical fishes. In the semiarid tropical region of Brazil the factors that influence fish reproduction are changes in rainfall regimes and drought. These environmental changes can either stimulate or inhibit reproduction in fishes. Information on these fundamental variables on reproduction can help management and conservation of tropical fishes. Information on fish reproduction also is an important factor for understanding the freshwater ecosystems of the semiarid region. This paper is a narrative review on the effects caused by rainfall and drought on reproduction of some cichlids and an annual fish from the semiarid region of Brazil. During the breeding period cichlid fishes demonstrate aggressive behavior and dominant fishes often get priority of access to territories and mates. On the other hand, the annual fishes have rapid growth and gonadal development to complete their life cycle within a short span of time. Fishes which are subjected to varying pluvial pressures have characteristic life history patterns.

Tropical semi-arid regions suffer with recurrent droughts and uncertain water availability, but a few research studies have been conducted to further understand those complexities and their relationships with reservoir hydrodynamics. This study assessed the hydrodynamic processes of a multiple-use reservoir located in the Brazilian semiarid region. The aim was to apply the CE-QUAL-W2 model to understand the lake’s thermal structure and its variabilities in time and space by using the Richardson’s number (Ri) as a reference. Meteorological patterns were also investigated. Results show that: (1) no significant changes were found by analysing the spatial variabilities of stratification; (2) seasonal changes were relevant as more robust stratification stability was observed in the wet period when water availability may be impacted by poor water quality; (3) from meteorological evaluations, rainfall showed a strong coefficient of determination with Ri (r² of 0.77); and (4) a threshold value of 60 mm in monthly precipitation was found as an indication of a stable stratification in the water column. Wind speed and water level partly influenced Ri’s variabilities, while low impact was noted for air temperature and inflow. These results can promote an improvement in water-resources management by linking rainfall regime and reservoir hydrodynamics.

Department of Invertebrate Zoology andHydrobiology, University of Lodz, Lodz, PolandSummaryThe Amur sleeper diet spectrum was investigated in addition toits spatial, seasonal and size-related changes, in order topredict which groups of native prey would be most affected bythis exotic predator that has rapidly invaded many Eastern andCentral European inland waters in recent decades. In total, 527Perccottus glenii individuals were collected in four sites in theWloclawski Reservoir (the Vistula River, Baltic basin, Po-land). Altogether 50 food categories were identified, includingcrustaceans, insects, molluscs, annelids, araneids, fishes andamphibians. Most of them were associated with aquaticvegetation, indicating that the Amur sleeper collects its preyfrom the submerged plants rather than directly from thebottom sediments. Amphipods and chironomid larvae, sup-plemented by zygopteran larvae and molluscs, composed themain forage base in all studied sites, although their importancewas varied. The diet composition differed among P. glenii size-groups. Significant variation was found in numeric abundanceof amphipods, chironomid larvae, fish and zygopteran larvae(Kruskal–Wallis P < 0.01). Seasonal changes in the diet werealso observed whereby in spring and summer, dipteran larvaeand amphipods were prevalent food items; the importance ofmolluscs and zygopteran larvae increased considerably inSeptember; and fish showed the highest occurrence in June,July and August. The broad diet spectrum of the Amur sleeperindicates that it is a non-selective, opportunistic predator andthat several taxonomic groups of native hydrofauna as well asmacroinvetebrates and fish may be affected by its presence.The highly flexible feeding strategy undoubtedly favours Amursleeper expansion in invaded watersheds.IntroductionMost definitions of invasive alien species underline theirnegative effects on native ecosystems and the threats that theirspread cause to local biological diversity. One of the possibleecological impacts of invasive fishes is alteration of trophicrelationships in aquatic communities that can be happen in atleast three different ways. First, non-native species mayincrease the amount of prey available to native predators.Second, the aliens can reduce food resources available tonative species through a dietary overlap. Finally, if the invasivefish is a predator, it can profoundly affect the populationdynamics of indigenous prey species (Moyle and Light, 1996;Simon and Townsend, 2003). The latter threat appears to bethe most drastic.The case of the Amur sleeper is among the most impressiverecent East-to-West invasions in European inland waters(Copp et al., 2005). Of Far East origin (mainly from AmurRiver system), it was first introduced into European areas ofRussia in 1912, and soon spread to the former Soviet Union(Reshetnikov, 2004). In the 1990s its rapid expansion was alsoobserved in the Vistula River system in Poland (Terlecki andPalka, 1999; Kostrzewa et al., 2004), along the Danube and itstributaries in Hungary (Harka, 1998), Slovakia (Kosˇcˇo et al.,2003), Serbia (Gergely and Tucakov, 2004; Hegedisˇ et al.,2007), Romania (Nalbant et al., 2004) and Bulgaria (Jurajdaet al., 2006).Perccottus glenii is a predator with morphological featuresenabling it to hunt a broad variety of aquatic organismsincluding relatively large prey items (Miller and Vasileva,2003). Its diet was studied mostly in its native range (Sinelni-kov, 1976) as well as some invaded ecosystems in Russia(Spanovskaya et al., 1964; Litvinov and OGorman, 1996;Reshetnikov, 2001, 2003, 2008). In all cases the species wasreported to be a voracious predator with a broad dietconstituting crustaceans (Cladocera, Copepoda, Malacostra-ca), larvae and insects (Ephemeroptera, Odonata, Hemiptera,Diptera, Trichoptera, Coleoptera), molluscs, fish, and evenlarvae of amphibians (frogs and newts) that are rarelyconsumed by other fish. Effects of the species predation onaquatic communities in small waterbodies in Russia werereported as deteriorative, as it was able to exhaust entire foodsupplies. Reshetnikov (2001, 2003) revealed that in smallwaterbodies the Amur sleeper depressed macroinvertebratepopulations as well as fishes, and that newts and frogs couldnot successfully reproduce due to predation pressure. As aresult, a negative correlation between the presence andabundance of P. glenii and the richness of aquatic specieswas observed. Long-term studies near Moscow (Spanovskayaet al., 1964) showed that the composition of consumed foodchanged along with the alterations caused to available prey inlocal communities. After the abrupt impoverishment of thelarge invertebrates fauna, the elimination of eggs, larvae andjuveniles of crucian carp and tadpoles in the P. glenii diet andcannibalistic behaviour was noted. This shows Amur sleeper tobe an effective switch-predator.It is expected that the recent rapid expansion of P. glenii inCentral European waters will cause a serious threat to localaquatic communities. Unfortunately, there are no data on itsfeeding habits in this region. Thus, the purpose of the presentstudy was to define the Amur sleeper diet spectrum, its spatial,seasonal and size related changes as well as to predict whichgroups of native prey would be most affected by the presenceof this exotic predator in the newly invaded locations in theexample of the Vistula River in Poland.

Arbuscular mycorrhizal (AM) fungi play a crucial role in carbon (C), nitrogen (N), and phosphorous (P) biogeochemical cycling. Therefore, it is essential to determine the seasonal responses of the AM fungal community to N addition to understanding better the ecological processes against a background of intensified N deposition. Based on an ongoing field simulation experiment with five N addition levels (0, 5, 10, 15, and 30 gN·m−2·a−1) in a 5-year-old poplar plantation at Dongtai Forest Farm in Yancheng, Jiangsu province, eastern China, soil physicochemical properties, the root colonization rate, and the rhizosphere soil AM fungal community diversity and composition in four seasons (summer, autumn, winter, and spring) were investigated. Meanwhile, the relationships between the characteristics of the AM fungal community and soil environmental factors were analyzed. High-throughput sequencing showed that the dominant genera in the poplar plantation were Glomus (average relative abundance 87.52%), Diversispora (9.62%), and Acaulospora (1.85%). The addition of N significantly increased the root colonization rate in spring. The diversity of the AM fungal community (Chao and Shannon indexes) was primarily affected by seasonal change rather than N addition, and the diversity in summer was significantly lower than in the other three seasons. Redundancy analysis showed that soil temperature, available P, total P, and pH significantly affected the structure of the AM fungal community. It can be concluded N addition primarily influenced the root colonization rate, whereas seasonal change had a notable effect on the AM fungal community diversity. Although seasonal change and N addition greatly influenced the composition, seasonal change exerted a more substantial effect than N addition. These results will improve our understanding of the underground ecological processes in poplar plantation ecosystems.

In recent years, different responses of archaea and bacteria to environmental changes have attracted increasing scientific interest. In the mid-latitude region, Fen River receives water transferred from the Yellow River, electrical conductivity (EC), concentrations of Cl− and Na+ in water, total phosphorus (TP), and Olsen phosphorus (OP) in sediments were significantly affected by water transfer. Meanwhile, temperature and oxidation-reduction potential (ORP) of water showed significant seasonal variations. Based on 16S rRNA high-throughput sequencing technology, the composition of bacteria and archaea in sediments was determined in winter and summer, respectively. Results showed that the dominance of bacterial core flora decreased and that of archaeal core flora increased after water diversion. The abundance and diversity of bacterial communities in river sediments were more sensitive to anthropogenic and naturally induced environmental changes than that of archaeal communities. Bacterial communities showed greater resistance than archaeal communities under long-term external disturbances, such as seasonal changes, because of rich species composition and complex community structure. Archaea were more stable than bacteria, especially under short-term drastic environmental disturbances, such as water transfer, due to their insensitivity to environmental changes. These results have important implications for understanding the responses of bacterial and archaeal communities to environmental changes in river ecosystems affected by water diversion.

Oilseeds from five native plant species with edible potential from the Brazilian Caatinga semi-arid region (Diplopterys pubipetala, Barnebya harleyi, Croton adamantinus, Hippocratea volubilis, and Couroupita guianensis) were investigated regarding their mineral contents. The minerals, Na, K, Ca, Mg, Fe, Cu, Cr, Al, were analyzed by high-resolution continuum source atomic absorption spectrometry (HR–CS AAS) and P by the vanadomolybdophosphoric acid colorimetric method. K, Mg, and P were the main elements found (1.62–3.7 mg/g, 362–586 µg/g, and 224–499 µg/g dry weight (dw), respectively). B. harley seeds contained the highest amounts of K and P, while C. guianensis seeds were the richest in Mg. Fe was the most abundant oligoelement (2.3–25.6 µg/g dw). Cr contents were below the limit of quantification for all samples and Al amounts were low: 0.04–1.80 µg/g dw. A linear discriminant analysis clearly differentiated B. harleyi and C. guianensis samples from the remaining ones. In sum, these oilseeds from the Brazilian Caatinga semi-arid region seem to have the potential to be used as natural sources of minerals, mainly K.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 361:47-58 (2008) - DOI: https://doi.org/10.3354/meps07357 Effect of salmon cage aquaculture on the pelagic environment of temperate coastal waters: seasonal changes in nutrients and microbial community Nuria Navarro1,2,*, Raymond J. G. Leakey1, Kenneth D. Black1 1Scottish Association for Marine Science (SAMS), Dunstaffnage Marine Laboratory, Oban PA37 1QA, UK 2Present address: Área de Biodiversidad y Conservación, ESCET, Universidad Rey Juan Carlos, C/ Tulipán s/n, Móstoles 28933, Madrid, Spain *Email: nuria.navarro@urjc.es ABSTRACT: The effects of salmon farm inputs on pelagic nutrient concentrations and planktonic microbial abundance and biomass were investigated in Loch Fyne, a temperate fjordic environment off the west coast of Scotland. The concentration of photosynthetic pigments and inorganic and organic nutrients, and the abundance and biomass of the autotrophic and heterotrophic microorganisms, were determined over a complete annual cycle from 3 depths (5, 15 and 25–30 m) at 4 stations located at differing proximities to the fish farm. Ammonium and dissolved organic nitrogen concentrations and heterotrophic microbial abundance and biomass were significantly higher at the stations nearest to the fish farm, suggesting that these and other nutrients derived from the fish farm may be directly or indirectly enhancing heterotrophic microbial activity. This in turn suggests that the heterotrophic microbial food web was responsible, at least in part, for processing matter and energy released into the pelagic environment from the salmon farm. By contrast, pigment concentrations, including chlorophyll a, tended to be similar at all stations, supporting the conclusions of previous studies that failed to establish a clear relationship between fish farm inputs and phytoplankton biomass. As such, the response of the heterotrophic microbial community is probably a more appro-priate indicator than chlorophyll concentration of local ecological effects of fish farms in temperate coastal waters. KEY WORDS: Fish farm · Plankton community · Bacteria · Nutrients · Chlorophyll Full text in pdf format PreviousNextCite this article as: Navarro N, Leakey RJG, Black KD (2008) Effect of salmon cage aquaculture on the pelagic environment of temperate coastal waters: seasonal changes in nutrients and microbial community. Mar Ecol Prog Ser 361:47-58. https://doi.org/10.3354/meps07357 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 361. Online publication date: June 09, 2008 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2008 Inter-Research.

In dry deciduous tropical forests, both seasons (winter and summer) offer habitats that are essential ecologically. How these seasonal changes affect soil properties and microbial communities is not yet fully understood. This study aimed to investigate the influence of seasonal fluctuations on soil characteristics and microbial populations. The soil moisture content dramatically increases in the summer. However, the soil pH only gradually shifts from acidic to slightly neutral. During the summer, electrical conductivity (EC) values range from 0.62 to 1.03 ds m-1, in contrast to their decline in the winter. The levels of soil macronutrients and micronutrients increase during the summer, as does the quantity of soil organic carbon (SOC). A two-way ANOVA analysis reveals limited impacts of seasonal fluctuations and specific geographic locations on the amounts of accessible nitrogen (N) and phosphorus (P). Moreover, dehydrogenase, nitrate reductase, and urease activities rise in the summer, while chitinase, protease, and acid phosphatase activities are more pronounced in the winter. The soil microbes were identified in both seasons through 16S rRNA and ITS (Internal Transcribed Spacer) gene sequencing. Results revealed Proteobacteria and Ascomycota as predominant bacterial and fungal phyla. However, Bacillus, Pseudomonas, and Burkholderia are dominant bacterial genera, and Aspergillus, Alternaria, and Trichoderma are dominant fungal genera in the forest soil samples. Dominant bacterial and fungal genera may play a role in essential ecosystem services such as soil health management and nutrient cycling. In both seasons, clear relationships exist between soil properties, including pH, moisture, iron (Fe), zinc (Zn), and microbial diversity. Enzymatic activities and microbial shift relate positively with soil parameters. This study highlights robust soil-microbial interactions that persist mainly in the top layers of tropical dry deciduous forests in the summer and winter seasons. It provides insights into the responses of soil-microbial communities to seasonal changes, advancing our understanding of ecosystem dynamics and biodiversity preservation.

Deciphering the dual role of bacterial communities in stabilizing rhizosphere priming effect under intra-annual change of growing seasons