Mangroves enhance the biomass of coral reef fish communities in the Caribbean

Mangrove forests are one of the world's most threatened tropical ecosystems with global loss exceeding 35% (ref. 1). Juvenile coral reef fish often inhabit mangroves, but the importance of these nurseries to reef fish population dynamics has not been quantified. Indeed, mangroves might be expected to have negligible influence on reef fish communities: juvenile fish can inhabit alternative habitats and fish populations may be regulated by other limiting factors such as larval supply or fishing. Here we show that mangroves are unexpectedly important, serving as an intermediate nursery habitat that may increase the survivorship of young fish. Mangroves in the Caribbean strongly influence the community structure of fish on neighbouring coral reefs. In addition, the biomass of several commercially important species is more than doubled when adult habitat is connected to mangroves. The largest herbivorous fish in the Atlantic, Scarus guacamaia, has a functional dependency on mangroves and has suffered local extinction after mangrove removal. Current rates of mangrove deforestation are likely to have severe deleterious consequences for the ecosystem function, fisheries productivity and resilience of reefs. Conservation efforts should protect connected corridors of mangroves, seagrass beds and coral reefs

Infestation of Transgenic Powdery Mildew-Resistant Wheat by Naturally Occurring Insect Herbivores under Different Environmental Conditions

A concern associated with the growing of genetically modified (GM) crops is that they could adversely affect non-target organisms. We assessed the impact of several transgenic powdery mildew-resistant spring wheat lines on insect herbivores. The GM lines carried either the Pm3b gene from hexaploid wheat, which confers race-specific resistance to powdery mildew, or the less specific anti-fungal barley seed chitinase and β-1,3-glucanase. In addition to the non-transformed control lines, several conventional spring wheat varieties and barley and triticale were included for comparison. During two consecutive growing seasons, powdery mildew infection and the abundance of and damage by naturally occurring herbivores were estimated under semi-field conditions in a convertible glasshouse and in the field. Mildew was reduced on the Pm3b-transgenic lines but not on the chitinase/glucanase-expressing lines. Abundance of aphids was negatively correlated with powdery mildew in the convertible glasshouse, with Pm3b wheat plants hosting significantly more aphids than their mildew-susceptible controls. In contrast, aphid densities did not differ between GM plants and their non-transformed controls in the field, probably because of low mildew and aphid pressure at this location. Likewise, the GM wheat lines did not affect the abundance of or damage by the herbivores Oulema melanopus (L.) and Chlorops pumilionis Bjerk. Although a previous study has revealed that some of the GM wheat lines show pleiotropic effects under field conditions, their effect on herbivorous insects appears to be low

Fungal microbiomes are determined by host phylogeny and exhibit widespread associations with the bacterial microbiome

Interactions between hosts and their resident microbial communities are a fundamental component of fitness for both agents. Though recent research has highlighted the importance of interactions between animals and their bacterial communities, comparative evidence for fungi is lacking, especially in natural populations. Using data from 49 species, we present novel evidence of strong covariation between fungal and bacterial communities across the host phylogeny, indicative of recruitment by hosts for specific suites of microbes. Using co-occurrence networks, we demonstrate that fungi form critical components of putative microbial interaction networks, where the strength and frequency of interactions varies with host taxonomy. Host phylogeny drives differences in overall richness of bacterial and fungal communities, but the effect of diet on richness was only evident in mammals and for the bacterial microbiome. Collectively these data indicate fungal microbiomes may play a key role in host fitness and suggest an urgent need to study multiple agents of the animal microbiome to accurately determine the strength and ecological significance of host-microbe interactions. SIGNIFICANCE STATEMENT Microbes perform vital metabolic functions that shape the physiology of their hosts. However, almost all research to date in wild animals has focused exclusively on the bacterial microbiota, to the exclusion of other microbial groups. Although likely to be critical components of the host microbiome, we have limited knowledge of the drivers of fungal composition across host species. Here we show that fungal community composition is determined by host species identity and phylogeny, and that fungi form extensive interaction networks with bacteria in the microbiome of a diverse range of animal species. This highlights the importance of microbial interactions as mediators of microbiome-health relationships in the wild

Characterising the bacterial microbiota of Phlebotomus and Glossina insects : vectors of parasitic diseases

As the technology used to examine bacteria using culture-independent methods has advanced, so too has our knowledge of the bacterial microbiome of insect vectors and its effect on the pathogens they carry. Trypanosomiasis and leishmaniasis are neglected tropical diseases caused by kinetoplast parasites and transmitted between human hosts by biting flies. In this thesis the bacterial microbiota of tsetse flies and sand flies, the vectors of trypanosomiasis and leishmaniasis respectively, were examined using molecular biology and next generation sequencing to understand their distribution in wild populations and their impact on pathogen transmission.An experimentally evolved isolate of the tsetse secondary endosymbiont Sodalis glossinidius (SgGMMC1*), which is believed to increase tsetse susceptibility to trypanosome infection, was sequenced and compared to an ancestor S. glossinidius strain (SgGMMB4). SgGMMC1* contained a single large 17 kb deletion as well as 57 small indels and SNPs resulting in 12 putatively pseudogenised genes, supporting the theory that the S. glossinidius genome is undergoing evolutionary reduction.The distribution of known tsetse symbionts including Sodalis and Spiroplasma, as well as the trypanosome parasite, was explored in wild Ugandan tsetse populations. Sodalis was detected in 39% of wild-caught tsetse, Wolbachia in 1.7%, Spiroplasma in 88% and Trypanosoma in 12%, providing essential information about the ecology of these symbiotic organisms in wild populations.Lab-reared tsetse flies were experimentally infected with trypanosomes to examine metatranscriptional differences of commensal bacteria between trypanosome-refractory and successfully infected flies. Wigglesworthia expression differed over time but not between refractory and infected tsetse; in Sodalis virulence genes were upregulated in trypanosome infected flies compared to refractory flies; and little effect of trypanosome infection on Serratia or Wolbachia transcription was observed. These results suggest that increased Sodalis virulence may increase tsetse susceptibility to trypanosome infection.Finally, a novel 16S sequencing pipeline for low-biomass individual sand flies was designed and implemented on wild Phlebotomus argentipes, the vector of visceral leishmaniasis in the Bihar region of India, to discover variation in individual sand fly microbiota within and between houses, villages, and larger districts. A pipeline was optimised to reduce the effect of contamination in low-biomass samples, allowing the description of a core microbiome of seven genera including Corynebacterium, Acinetobacter, and Staphylococcus. A variable peripheral microbiome was discovered with no effect of geographical location, and included the important human pathogen Orientia, implying a potential role for P. argentipes in Orientia transmission

The variability of the North Atlantic marine atmosphere and its relevance to remote sensing

Results are presented describing the seasonal changes in the marine atmosphere of variables relevant to infrared remote sensing from satellites and aircraft. The area is restricted to that of the north-eastern Atlantic Ocean and adjacent seas. The description has been derived from a large number of radiosonde profiles from the archive of the U.K. Meteorological Office