Scleractinian corals form the foundation of coral reefs by acquiring autotrophic nutrition from photosynthetic endosymbionts (Symbiodiniaceae) and use feeding to obtain additional nutrition, especially when the symbiosis is compromised (i.e. bleaching). Juvenile corals are vulnerable to stress due to low energetic reserves and high demand for growth, which is compounded when additional stressors occur. Therefore, conditions that favour energy acquisition and storage may enhance survival under stressful conditions. To investigate the influence of feeding on thermal tolerance, we exposed Pocillopora acuta juveniles to temperature (ambient, 27.4°C versus cool, 25.9°C) and feeding treatments (fed versus unfed) for 30 days post-settlement and monitored growth and physiology, followed by tracking survival under thermal stress. Feeding increased growth and resulted in thicker tissues and elevated symbiont fluorescence. Under high-temperature stress (31–60 days post-settlement; ca 30.1°C), corals that were fed and previously exposed to cool temperature had 33% higher survival than other treatment groups. These corals demonstrated reduced symbiont fluorescence, which may have provided protective effects under thermal stress. These results highlight that the impacts of feeding on coral physiology and stress tolerance are dependent on temperature and as oceans continue to warm, early life stages may experience shifts in feeding strategies to survive.
The epidermis of Chondrichthyan fishes consists of dermal denticles with production of minimal but protein-rich mucus that collectively, influence the attachment and biofilm development of microbes, facilitating a unique epidermal microbiome. Here, we use metagenomics to provide the taxonomic and functional characterization of the epidermal microbiome of the Triakis semifasciata (leopard shark) at three time-points collected across 4 years to identify links between microbial groups and host metabolism. Our aims include (1) describing the variation of microbiome taxa over time and identifying recurrent microbiome members (present across all time-points); (2) investigating the relationship between the recurrent and flexible taxa (those which are not found consistently across time-points); (3) describing the functional compositions of the microbiome which may suggest links with the host metabolism; and (4) identifying whether metabolic processes are shared across microbial genera or are unique to specific taxa. Microbial members of the microbiome showed high similarity between all individuals (Bray–Curtis similarity index = 82.7, where 0 = no overlap, 100 = total overlap) with the relative abundance of those members varying across sampling time-points, suggesting flexibility of taxa in the microbiome. One hundred and eighty-eight genera were identified as recurrent, including Pseudomonas, Erythrobacter, Alcanivorax, Marinobacter, and Sphingopxis being consistently abundant across time-points, while Limnobacter and Xyella exhibited switching patterns with high relative abundance in 2013, Sphingobium and Sphingomona in 2015, and Altermonas, Leeuwenhoekiella, Gramella, and Maribacter in 2017. Of the 188 genera identified as recurrent, the top 19 relatively abundant genera formed three recurrent groups. The microbiome also displayed high functional similarity between individuals (Bray–Curtis similarity index = 97.6) with gene function composition remaining consistent across all time-points. These results show that while the presence of microbial genera exhibits consistency across time-points, their abundances do fluctuate. Microbial functions however remain stable across time-points; thus, we suggest the leopard shark microbiomes exhibit functional redundancy. We show coexistence of microbes hosted in elasmobranch microbiomes that encode genes involved in utilizing nitrogen, but not fixing nitrogen, degrading urea, and resistant to heavy metal.
Determination of species within the genus Cannabis has important legal medical and social implications. Recent genome sequencing has shown that the genomes of C. sativa (recreational marijuana and hemp), C. indica (medical marijuana) and C. ruderalis (feral marijuana) can all be distinguished. However, hybridization among the species has occurred with widely varying outcomes in the percent of genome transmitted. The aim here was to determine if a simple assay based on the DNA sequence of ITS2 could be used to distinguish among species. Using sequences at GenBank as a reference eighteen plant samples were sequenced and shown to be identical to C. indica sequence and different from C. sativa and C. ruderalis at 4 positions within the 25S rRNA gene. This result and the geographic separation of the centers of genetic diversity argues strongly for polytypic origins of the 3 species. Analysis of interspecific hybrids sequences at GenBank suggested only the C. indica allele is transmitted preferentially. Finally, a SNP within the ITS could be used to distinguish two types within the eighteen plants. Therefore this simple genetic test can be used for rapid plant identification and to assist in strain identification.
Background: The epidermis of Chondrichthyan fishes consists of dermal denticles with production of minimal but protein rich mucus that influence the attachment and biofilm development of microbes, facilitating a unique epidermal microbiome. Here, we use metagenomics to provide the taxonomic and functional characterization of the epidermal microbiome of the Triakis semifasciata (leopard shark) across three time-points to identify links between microbial groups and host metabolism. Our aims include 1) describing the variation of microbiome taxa over time and identify those members which are recurrent (present across all time-points, 2) investigating the relationship between the recurrent and flexible taxa (those which are not found consistently across time-points, 3) describing the functional compositions of the microbiome which may suggest links with the host metabolism; and 4) identifying whether the metabolisms are share across microbial genera or found in specific taxa. Results: Microbial members of the microbiome showed high similarity between all individuals (average similarity: 82.74) with relative abundance of those members varying across years, suggesting flexibility of taxa in the microbiome. One hundred and eighty-eight genera were identified as recurrent, including Pseudomonas, Erythrobacter, Alcanivorax, Marinobacter and Sphingopxis being consistently abundance across time-points, while Limnobacter and Xyella exhibited switching patterns with high relative abundance in 2013, Sphingobium and Sphingomona in 2015, and Altermonas, Leeuwenhoekiella, Gramella and Maribacter in 2017. Of the 188 genera identified as recurrent, the top 19 relative abundant genera forming three recurrent groups. The microbiome also displayed high functional similarity between individuals (average similarity: 97.65) with gene function composition being consistent across time-points. Conclusion: These results show that while presence of microbial genera exhibit consistency across time-points, their abundances do fluctuate. Functions however remain stable across time points; thus, we suggest the leopard shark microbiomes exhibit functional redundancy. We hypothesize this may be the result of the host’s epidermal attributes structuring the microbiome. In addition, we show the co-existence of many microbial genera that carry genes which may enable the microbes to use the nutrients provided by the elasmobranch’s metabolism.
Background: Characterizations of sharks-microbe systems in wild environments have outlined patterns of species-specific microbiomes; however, whether captivity affects these trends has yet to be determined. We used high-throughput shotgun sequencing to assess the epidermal microbiome belonging to leopard sharks (Triakis semifasciata) in captive (Birch Aquarium, La Jolla California), semi-captive (<1 year in captivity; Scripps Institute of Oceanography, California) and wild environments (Moss Landing and La Jolla, California). Results: Here we report captive environments do not drive microbiome composition of T. semifasciata to significantly diverge from wild counterparts as life-long captive sharks maintain a species-specific epidermal microbiome resembling those associated with semi-captive and wild populations. Major taxonomic composition shifts observed were inverse changes of top taxonomic contributors across captive duration, specifically an increase of Pseudoalteromonadaceae and consequent decrease of Pseudomonadaceae relative abundance as T. semifasciata increased duration in captive conditions. Moreover, we show captivity did not lead to significant losses in microbial α-diversity of shark epidermal communities. Finally, we present a novel association between T. semifasciata and the Muricauda genus as MAGs revealed a consistent relationship across captive, semi-captive, and wild populations. Conclusions: Our report illustrates the importance of conservation programs for coastal fishes as epidermally-associated microbes of near-shore shark species do not suffer detrimental impacts from long or short-term captivity. Our findings also expand on current understanding of shark epidermal microbiomes, explore the effects of ecologically different scenarios on benthic shark microbe associations, and highlight novel microbial associations that are consistent across captive gradients.
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