Enrichable consortia of microbial symbionts degrade macroalgal polysaccharides in Kyphosus fish.

Coastal herbivorous fishes consume macroalgae, which is then degraded by microbes along their digestive tract. However, there is scarce genomic information about the microbiota that perform this degradation. This study explores the potential of Kyphosus gastrointestinal microbial symbionts to collaboratively degrade and ferment polysaccharides from red, green, and brown macroalgae through in silico study of carbohydrate-active enzyme and sulfatase sequences. Recovery of metagenome-assembled genomes (MAGs) from previously described Kyphosus gut metagenomes and newly sequenced bioreactor enrichments reveals differences in enzymatic capabilities between the major microbial taxa in Kyphosus guts. The most versatile of the recovered MAGs were from the Bacteroidota phylum, whose MAGs house enzyme collections able to decompose a variety of algal polysaccharides. Unique enzymes and predicted degradative capacities of genomes from the Bacillota (genus Vallitalea) and Verrucomicrobiota (order Kiritimatiellales) highlight the importance of metabolic contributions from multiple phyla to broaden polysaccharide degradation capabilities. Few genomes contain the required enzymes to fully degrade any complex sulfated algal polysaccharide alone. The distribution of suitable enzymes between MAGs originating from different taxa, along with the widespread detection of signal peptides in candidate enzymes, is consistent with cooperative extracellular degradation of these carbohydrates. This study leverages genomic evidence to reveal an untapped diversity at the enzyme and strain level among Kyphosus symbionts and their contributions to macroalgae decomposition. Bioreactor enrichments provide a genomic foundation for degradative and fermentative processes central to translating the knowledge gained from this system to the aquaculture and bioenergy sectors.IMPORTANCESeaweed has long been considered a promising source of sustainable biomass for bioenergy and aquaculture feed, but scalable industrial methods for decomposing terrestrial compounds can struggle to break down seaweed polysaccharides efficiently due to their unique sulfated structures. Fish of the genus Kyphosus feed on seaweed by leveraging gastrointestinal bacteria to degrade algal polysaccharides into simple sugars. This study reconstructs metagenome-assembled genomes for these gastrointestinal bacteria to enhance our understanding of herbivorous fish digestion and fermentation of algal sugars. Investigations at the gene level identify Kyphosus guts as an untapped source of seaweed-degrading enzymes ripe for further characterization. These discoveries set the stage for future work incorporating marine enzymes and microbial communities in the industrial degradation of algal polysaccharides.

Increased occurrence of the rare golden color morph of Pacific chub Kyphosus sandwicensis in a no-take marine reserve.

Pacific chub, Kyphosus sandwicensis, are typically gray but some individuals display a golden color morph. We estimated that the frequency of occurrence of the golden morphs increased significantly from 2007 (1.9%) and 2012 (2.6%) to 2017 (5.0%) inside a no-take marine reserve around Nihoa Island in the Northwestern Hawaiian Islands. While sporadic observations of a golden color morph have been noted for several other marine fish species, we provide a quantitative estimate of changes in the frequency of occurrence of the morph within a wild marine population.

Enrichable consortia of microbial symbionts degrade macroalgal polysaccharides in Kyphosus fish.

Coastal herbivorous fishes consume macroalgae, which is then degraded by microbes along their digestive tract. However, there is scarce foundational genomic work on the microbiota that perform this degradation. This study explores the potential of Kyphosus gastrointestinal microbial symbionts to collaboratively degrade and ferment polysaccharides from red, green, and brown macroalgae through in silico study of carbohydrate-active enzyme and sulfatase sequences. Recovery of metagenome-assembled genomes (MAGs) reveals differences in enzymatic capabilities between the major microbial taxa in Kyphosus guts. The most versatile of the recovered MAGs were from the Bacteroidota phylum, whose MAGs house enzymes able to decompose a variety of algal polysaccharides. Unique enzymes and predicted degradative capacities of genomes from the Bacillota (genus Vallitalea) and Verrucomicrobiota (order Kiritimatiellales) suggest the potential for microbial transfer between marine sediment and Kyphosus digestive tracts. Few genomes contain the required enzymes to fully degrade any complex sulfated algal polysaccharide alone. The distribution of suitable enzymes between MAGs originating from different taxa, along with the widespread detection of signal peptides in candidate enzymes, is consistent with cooperative extracellular degradation of these carbohydrates. This study leverages genomic evidence to reveal an untapped diversity at the enzyme and strain level among Kyphosus symbionts and their contributions to macroalgae decomposition. Bioreactor enrichments provide a genomic foundation for degradative and fermentative processes central to translating the knowledge gained from this system to the aquaculture and bioenergy sectors.

Cadmium, Lead, Copper, Zinc, and Iron Concentration Patterns in Three Marine Fish Species from Two Different Mining Sites inside the Gulf of California, Mexico.

In the Gulf of California; mineral deposits have contributed to high metal contents in coastal environments. This study examined cadmium; lead; copper; zinc; and iron contents in three fish species; Kyphosus vaigiensis (herbivore), Stegastes rectifraenum (omnivore), and Balistes polylepis (carnivore) at two mining sites. Metal concentrations were analyzed by atomic absorption spectrophotometry and stable nitrogen and carbon isotopes were estimated using mass spectrophotometry. Also, we assessed the risk to human health from the consumption of these three species based on permissible limits; although only two of them (Kyphosus and Balistes) are consumed as food. Metal concentrations differed among fish species; except for iron. The highest concentrations of metals were not always recorded in the species at the highest trophic level; i.e., Balistes. The highest concentrations (dry weight) recorded were cadmium (0.21 ± 0.03 µg g-1) and lead (1.67 ± 0.26 µg g-1), in S. rectifraenum; copper (1.60 ± 0.49 µg g-1) and zinc (67.30 ± 8.79 µg g-1), in B. polylepis; and iron (27.06 ± 2.58 µg g-1), in K. vaigiensis. Our findings show that each element accumulates differently in particular marine organisms; depending on the physiology of the species and the biogeochemistry of its habitat; which in turn is affected by the anthropogenic activities in adjacent areas. No risk of heavy metals toxicity is expected from the human consumption of the species and sites studied.

A New Species of the Acanthocephalan Genus Filisoma (Cavisomidae) from Perciform Fishes in Rio de Janeiro, Brasil.

BACKGROUND: Twelve species of Filisoma Van Cleave, 1928 are recognized parasitizing tropical and subtropical fish. Four of these species were described from kyphosid fish and it has been suggested that a co-speciation may have occurred among species of Kyphosus Lacepède, 1801 and Filisoma, which could provide valuable information about the evolution history of this host-parasite system. PURPOSE: During a survey of the helminth fauna of Kyphosus sectatrix (Linnaeus, 1758) and Kyphosus incisor (Cuvier, 1831) (Kyphosidae Jordan, 1887) off Rio de Janeiro coast, a new species of Filisoma was found and is described herein based on morphological, genetic, and ultrastructural data. METHODS: Fish were obtained off Rio de Janeiro coast, Brazil. The parasites found in the intestine were measured and drawings were made with a drawing tube. Type specimens were deposited at the Helminthological Collection of Oswaldo Cruz Institute (CHIOC). The ultrastructure was studied using scanning electron microscope. The genetic analysis included the study of the partial sequences of 18S, ITS1, 5.8S and 28S rDNA, and the mitochondrial cytochrome c oxidase 1 gene (cox 1), with phylogenetic reconstructions based on the maximum likelihood analysis. RESULTS: Filisoma caudata n. sp. is characterized by a proboscis with 16‒18 longitudinal rows of 38‒45 hooks each. Hooks are uniform in shape dorsoventrally, gradually decreasing in size towards the base of the proboscis. Anterior hooks are 30‒45 µ long, middle hooks 30‒35 µ long and 5 basal transversal hooks 20‒30 µ long. The new species is differentiated from the closest species Filisoma filiformis Weaver and Smales, 2013 by the size and distribution of hooks, apart from having a subterminal vulva and a curved posterior trunk end (tail) measuring 500‒1,000 long. Phylogenetic analysis based on 18S, 28S rDNA and mtDNA-cox1 markers grouped the new species with Filisoma bucerium Van Cleave, 1940 and Filisoma rizalinum Tubangui and Masiluñgan, 1946 showing a close relationship between these species of Cavisomidae Meyer, 1932 and Echinorhynchidae Cobbold, 1879; the latter represented by species of Acanthocephalus Koelreuther, 1771. The new species can be differentiated from others on morphological and molecular basis. A key to the 13 species of Filisoma Van Cleave, 1928 is provided. CONCLUSION: Filisoma caudata n. sp. is described herein based on morphological, genetic, and ultrastructural data. The topologies of obtained phylogenies suggest that species of Echinorhynchidae should be reevaluated since the family is considered paraphyletic in all analyses conducted.

Input data for inferring species distributions in Kyphosidae world-wide.

Input data files for inferring the relationship among the family Kyphosidae, as presented in (Knudsen and Clements, 2016) [1], is here provided together with resulting topologies, to allow the reader to explore the topologies in detail. The input data files comprise seven nexus-files with sequence alignments of mtDNA and nDNA markers for performing Bayesian analysis. A matrix of recoded character states inferred from the morphology examined in museum specimens representing Dichistiidae, Girellidae, Kyphosidae, Microcanthidae and Scorpididae, is also provided, and can be used for performing a parsimonious analysis to infer the relationship among these perciform families. The nucleotide input data files comprise both multiple and single representatives of the various species to allow for inference of the relationship among the species in Kyphosidae and between the families closely related to Kyphosidae. The '.xml'-files with various constrained relationships among the families potentially closely related to Kyphosidae are also provided to allow the reader to rerun and explore the results from the stepping-stone analysis. The resulting topologies are supplied in newick-file formats together with input data files for Bayesian analysis, together with '.xml'-files. Re-running the input data files in the appropriate software, will enable the reader to examine log-files and tree-files themselves.

World-wide species distributions in the family Kyphosidae (Teleostei: Perciformes).

Sea chubs of the family Kyphosidae are major consumers of macroalgae on both temperate and tropical reefs, where they can comprise a significant proportion of fish biomass. However, the relationships and taxonomic status of sea chubs (including the junior synonyms Hermosilla, Kyphosus, Neoscorpis and Sectator) worldwide have long been problematical due to perceived lack of character differentiation, complicating ecological assessment. More recently, the situation has been further complicated by publication of conflicting taxonomic treatments. Here, we resolve the relationships, taxonomy and distribution of all known species of sea chubs through a combined analysis of partial fragments from mitochondrial markers (12s, 16s, cytb, tRNA -Pro, -Phe, -Thr and -Val) and three nuclear markers (rag1, rag2, tmo4c4). These new results provide independent evidence for the presence of several junior synonyms among Atlantic and Indo-Pacific taxa, demonstrating that several sea chub species are more widespread than previously thought. In particular, our results can reject the hypothesis of endemic species in the Atlantic Ocean. At a higher taxonomic level, our results shed light on the relationships between Girellidae, Kuhliidae, Kyphosidae, Microcanthidae, Oplegnathidae and Scorpididae, with Scorpididae resolved as the sister group to Kyphosidae.

Does the abundance of girellids and kyphosids correlate with cover of the palatable green algae, Ulva spp.? A test on temperate rocky intertidal reefs.

This study assessed whether the abundance of girellids and kyphosids was related to cover of the palatable green algae, Ulva australis and Ulva compressa, on rocky intertidal reefs in Jervis Bay, New South Wales, Australia. No relationship was found between Ulva spp. cover and abundance of Girella tricuspidata, Girella elevata and Kyphosus sydneyanus during a period of relatively low Ulva spp. cover (i.e. February 2011 to March 2011), but during a period of significantly higher Ulva spp. cover (i.e. October 2011 to November 2011) there was a strong correlation between Ulva spp. cover and G. tricuspidata abundance. Spatial analysis indicated that the abundance of G. tricuspidata was consistent across time, suggesting G. tricuspidata were not moving between reefs in response to variation in Ulva spp. cover between periods but rather that large schools of G. tricuspidata resided on reefs that had relatively higher Ulva spp. cover at certain times of the year.

Pseudascarophis brasiliensis sp. nov. (Nematoda: Cystidicolidae) parasitic in the Bermuda chub Kyphosus sectatrix (Perciformes: Kyphosidae) from southeastern Brazil

A new species of Pseudascarophis (Nematoda: Cystidicolidae) found in the stomach of Kyphosus sectatrix (Linnaeus) (Kyphosidae), off Rio de Janeiro, Brazil, is described. The new species can be differentiated from the other congeners by the presence of lateral alae, distinct but inconspicuous cephalic papillae at the anterior end, three pairs of precloacal and one pair of adcloacal papillae in males, egg morphology and morphometry of glandular oesophagus and spicules. Pseudascarophis tropica is transferred to Ascarophis as Ascarophis tropica (Solov'eva) comb. n. due to its ambiguous diagnosis.

Revision of the fish family Kyphosidae (Teleostei: Perciformes).

A molecular phylogenetic analysis with complete species sampling of the family Kyphosidae revealed several discrepancies with the current taxonomy. We thus undertook a complete taxonomic revision of all kyphosid genera, i.e. Kyphosus Lacepède, 1801, and the monotypic Hermosilla Jenkins and Evermann, 1889, Sectator Jordan and Evermann, 1903 and Neoscorpis Smith, 1931. Species delimitation was determined on the basis of congruence between (a) monophyletic groupings in the molecular phylogeny, and (b) clusters of morphological variation in type material. Twelve species are supported and redescribed. Both Hermosilla and Sectator are considered junior synonyms of Kyphosus. Kyphosus azureus (Jenkins & Evermann, 1889) and K. ocyurus (Jordan & Gilbert, 1882) are redescribed accordingly. We designate a neotype for Kyphosus cornelii (Whitley, 1944), as the original material is lost, and new material was collected at the type locality for this study to facilitate comparison with other species of Kyphosus. Kyphosus sandwicensis (sensu Sauvage, 1880) was found to be a junior synonym of K. elegans (Peters, 1869). Kyphosus incisor (Cuvier in Cuvier & Valenciennes, 1831) and K. analogus (Gill, 1862) are considered junior synonyms of K. vaigiensis (Quoy & Gaimard, 1825). Kyphosus gallveii (Cunningham, 1910), K. pacificus Sakai and Nakabo, 2004 and K. lutescens (Jordan & Gilbert, 1882) are all considered junior synonyms of K. sectatrix (Linnaeus, 1758). One of the two syntype specimens of K. sectatrix was identified as the holotype of Pimelepterus bosquii (Lacepède, 1802), and proved to be a specimen of K. bigibbus Lacepède, 1801. This specimen is re-assigned as a non-type of K. bigibbus. Full re-descriptions of the following valid species are presented: K. bigibbus, K. cinerascens (Forsskål, 1775), K. cornelii, K. elegans, K. hawaiiensis Sakai and Nakabo, 2004, K. gladius Knudsen and Clements, 2013, K. sydneyanus (Günther, 1886) and K. vaigiensis, together with a key to the family. The distribution of Kyphosus species is reconsidered based on our taxonomic revision, indicating that four species (K. bigibbus, K. cinerascens, K. sectatrix and K. vaigiensis) occur in both the Atlantic and Indo-Pacific regions.