Understanding the complex, non-linear ways in which linked ecological and geomorphological systems respond to disturbance is important to improving both theoretical understanding and practical environmental management. Some simple conceptual models have been proposed to describe biogeomorphological responses to disturbance within fluvial and aeolian environments, and are reviewed here. Recent research on the interactions between ecological and geomorphological processes in rock breakdown, aeolian, hillslope, fluvial and coastal wetland process regimes indicates a number of additional factors which need to be considered by such models in order to provide a more realistic representation. In particular, many empirical studies point to complex interactions between vegetation, microphytic crusts and animal action (bioturbation and grazing) in a wide range of sediment systems, which act as intrinsic feedback factors complicating the response of these systems to disturbances such as climate change and human action. Improved understanding of these interactions will help effective environmental management, as exemplified by salt marsh restoration schemes. Furthermore, better specification of biogeomorphological interactions can provide insights into large-scale, long-term Earth systems dynamics problems such as the long-term carbon cycle.A simple model representing how geomorphological systems respond to disturbance (e.g. storm events, climate change, human activities) is shown in Figure 1. This model illustrates that geomorphological systems do not respond in a simple, linear fashion to disturbance, but that there are both lags and different response rate characteristics to forcing factors. One factor group (often described as feedback or intrinsic factors, e.g. Allen, 2000) which influences lag times and response rates is ecological change, such as vegetation growth and decay. All biotic influences on geomorphological processes can be seen to have either a stabilizing effect (i.e. reducing erosion and other processes through what some workers call 'bioprotection') or a destabilizing effect (i.e. enhancing erosion and other geomorphological processes) as shown in Table I. Biotic stabilization effects lead to negative feedbacks within geomorphological systems, whereas destabilization through biotic processes produces positive feedbacks. Understanding the operation of such stabilizing and destabilizing effects and how they interact with abiotic processes is vital for a fuller understanding of the response of geomorphological systems to disturbance.Looking at things from an ecological systems point of view, geomorphological processes can be seen to produce positive and negative feedbacks on ecosystem response to disturbance as illustrated in Table II. In some cases, geomorphological processes have stabilizing or destabilizing roles depending on their rate relative to the rate of plant growth, or animal activity. However, the picture is further complicated by interactions within ecological systems, e.g. grazing impacts on ve...

Tilapia lake virus (TiLV), a negative sense RNA virus with a 10 segment genome, is an emerging threat to tilapia aquaculture worldwide, with outbreaks causing over 90% mortality reported on several continents since 2014. Following a severe tilapia mortality event in July 2017, we confirmed the presence of TiLV in Bangladesh and obtained the near-complete genome of this isolate, BD-2017. Phylogenetic analysis of the concatenated 10 segment coding regions placed BD-2017 in a clade with the two isolates from Thailand, separate from the Israeli and South American isolates. However, phylogenetic analysis of individual segments gave conflicting results, sometimes clustering BD-2017 with one of the Israeli isolates, and splitting pairs of isolates from the same region. By comparing patterns of topological difference among segments of quartets of isolates, we showed that TiLV likely has a history of reassortment. Segments 5 and 6, in particular, appear to have undergone a relatively recent reassortment event involving Ecuador isolate EC-2012 and Israel isolate Til-4-2011. The phylogeny of TiLV isolates therefore depends on the segment sequenced. Our findings illustrate the need to exercise caution when using phylogenetic analysis to infer geographic origin and track the movement of TiLV, and we recommend using whole genomes wherever possible.

Article (refereed) -postprintCutler, Nick A.; Chaput, Dominique L.; van der Gast, Christopher J. 2014. Long-term changes in soil microbial communities during primary succession.Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. little is known about long-term (decades-centuries) structural changes in these communities. 22The development of aboveground-belowground linkages during century-scale succession is 23 also poorly understood. Our study addressed this knowledge gap by investigating SMC and 24 plant communities undergoing primary succession on an 850-year chronosequence of lava 25 flows in Iceland. We hypothesised that communities of microfungi and bacteria would 26 respond to progressive changes in vegetation and that SMC diversity would increase with 27 terrain age. Soil samples were collected from three lava flows at different stages of primary 28 succession (165, 621 and 852 years after lava flow emplacement). Plant community 29 composition was surveyed as the samples were collected. The composition of the SMCs 30 present in the soil was determined using amplicon pyrosequencing. The physical and 31 chemical properties of the soil were also analysed. The results of the study indicated 32 changes in plant and fungal communities with increasing terrain age. Distinct plant and 33 fungal assemblages were identified on the three sites and both communities became richer 34 and more diverse with increasing terrain age. There was also evidence to suggest the 35 development of mycorrhizal associations on older sites. In contrast, the composition and 36 structure of the bacterial communities did not change systematically with terrain age. 37Similarly, there were few changes in soil properties: SOM concentrations and pH, both of 38 which have been demonstrated to be important to SMCs, were constant across the 39 chronosequence. These results suggest that plant community composition is significant for 40 fungal communities, but less relevant for bacterial communities. This finding has implications 41 for studies of primary succession and the biogeochemical impact of vegetation change in 42 high-latitude ecosystems. 43 44

Fungal secretomes contain a wide range of hydrolytic and oxidative enzymes, including cellulases, hemicellulases, pectinases, and lignin-degrading accessory enzymes, that synergistically drive litter decomposition in the environment. While secretome studies of model organisms such as Phanerochaete chrysosporium and Aspergillus species have greatly expanded our knowledge of these enzymes, few have extended secretome characterization to environmental isolates or conducted side-by-side comparisons of diverse species. Thus, the mechanisms of carbon degradation by many ubiquitous soil fungi remain poorly understood. Here we use a combination of LC-MS/MS, genomic, and bioinformatic analyses to characterize and compare the protein composition of the secretomes of four recently isolated, cosmopolitan, Mn(II)-oxidizing Ascomycetes (Alternaria alternata SRC1lrK2f, Stagonospora sp. SRC1lsM3a, Pyrenochaeta sp. DS3sAY3a, and Paraconiothyrium sporulosum AP3s5-JAC2a). We demonstrate that the organisms produce a rich yet functionally similar suite of extracellular enzymes, with species-specific differences in secretome composition arising from unique amino acid sequences rather than overall protein function. Furthermore, we identify not only a wide range of carbohydrate-active enzymes that can directly oxidize recalcitrant carbon, but also an impressive suite of redox-active accessory enzymes that suggests a role for Fenton-based hydroxyl radical formation in indirect, non-specific lignocellulose attack. Our findings highlight the diverse oxidative capacity of these environmental isolates and enhance our understanding of the role of filamentous Ascomycetes in carbon turnover in the environment.