Hematological changes in Florida pompano (Trachinotus carolinus) supplemented with ß-glucan and Pediococcus acidilactici synbiotic.

Florida pompano (Trachinotus carolinus) are a species of growing interest for commercial aquaculture. Effective health monitoring is crucial to the successful growout of the species, and prophylactic and therapeutic use of chemicals and antibiotics has been the traditional strategy for promoting stock health. However, concerns about antimicrobial resistance, chemical residues in seafood products and the environment, and resultant immunosuppression have prompted the industry to identify alternative management strategies, including supplementation with prebiotics, probiotics, and combinations of both (synbiotics). The objectives of this study are to determine and compare hematological, plasma biochemical, and plasma protein electrophoresis data of synbiotic-supplemented (ß-glucan and Pediococcus acidilactici) and non-supplemented Florida pompano. Reference intervals for blood analytes are provided for both groups and for subgroups (females, males, large, and small fish) where statistically significant results exist. There are no differences between the hematological and plasma biochemistry analytes between the supplemented and control groups, except for blood urea nitrogen and carbon dioxide, indicating a possible effect of synbiotic supplementation on gill function and osmoregulation. Sex-related and size-related differences are observed within each of the control and supplemented groups; however, biometric measurements do not strongly correlate with blood analytes. These data represent baseline hematological and plasma biochemical data in the Florida pompano and indicate the safety of synbiotic supplementation in this commercially important species. This study serves to further the commercialization of Florida pompano by providing blood analyte reference intervals for health monitoring in the aquaculture setting.

Genome structures resolve the early diversification of teleost fishes.

Accurate species phylogenies are a prerequisite for all evolutionary research. Teleosts are the largest and most diversified group of extant vertebrates, but relationships among their three oldest extant lineages remain unresolved. On the basis of seven high-quality new genome assemblies in Elopomorpha (tarpons, eels), we revisited the topology of the deepest branches of the teleost phylogeny using independent gene sequence and chromosomal rearrangement phylogenomic approaches. These analyses converged to a single scenario that unambiguously places the Elopomorpha and Osteoglossomorpha (arapaima, elephantnose fish) in a monophyletic sister group to all other teleosts, i.e., the Clupeocephala lineage (zebrafish, medaka). This finding resolves more than 50 years of controversy on the evolutionary relationships of these lineages and highlights the power of combining different levels of genome-wide information to solve complex phylogenies.

Viruses of Atlantic Bonefish (Albula vulpes) in Florida and the Caribbean show geographic patterns consistent with population declines.

Atlantic Bonefish (Albula vulpes) are economically important due to their popularity with recreational anglers. In the State of Florida, USA, bonefish population numbers declined by approximately 60% between the 1990s and 2015. Habitat loss, water quality impairment, chemical inputs, and other anthropogenic factors have been implicated as causes, but the role of pathogens has been largely overlooked, especially with respect to viruses. We used a metagenomic approach to identify and quantify viruses in the blood of 103 A. vulpes sampled throughout their Western Atlantic range, including populations in Florida that have experienced population declines and populations in Belize, Mexico, Puerto Rico, and The Bahamas that have remained apparently stable. We identified four viruses, all of which are members of families known to infect marine fishes (Flaviviridae, Iflaviridae, Narnaviridae, and Nodaviridae), but all of which were previously undescribed. Bonefish from Florida and Mexico had higher viral richness (numbers of distinct viruses per individual fish) than fish sampled from other areas, and bonefish from the Upper Florida Keys had the highest prevalence of viral infection (proportion of positive fish) than fish sampled from any other location. Bonefish from Florida also had markedly higher viral loads than fish sampled from any other area, both for a novel narnavirus and for all viruses combined. Bonefish viruses may be indicators of environmentally driven physiological and immunological compromise, causes of ill health, or both. Supplementary information: The online version contains supplementary material available at 10.1007/s10641-022-01306-9.

The effects of fish meal substitution by clam meal on the growth and health of Florida pompano (Trachinotus carolinus).

A 12-week feeding trial was conducted to evaluate the effects of fish meal (FM) substitution by clam meal (CM, at 10%, 20% and 30% of the diet) on the growth, feed utilization, hepatic antioxidant enzymes, plasma parameters, fatty acid and amino acid composition, and gut microbiome of juvenile Florida pompano, Trachinotus carolinus. The results indicated that: (1) juveniles fed 10% and 20% CM had a significantly higher final weight than the group fed the control (0% CM); and the control group also showed significantly lower weight gain, feed intake, protein retention value, whole-body crude protein and total amino acids composition, but higher hepatosomatic index and whole-body crude fat; (2) hepatic peroxide content and superoxide dismutase activity were not significantly affected by the substitution of CM, but it did affect glutathione peroxidase activity, with higher levels found in fish fed 30% CM compared to 0% and 10% CM; (3) plasma total protein, alkaline phosphatase, alanine aminotransferase, and immunoglobulin M showed no significant differences among the treatments; (4) there were no significant differences among treatments in terms of fatty acids composition and microbial diversity. Overall, this study concluded that CM has comparable benefit in the diet of Florida pompano as FM does.

A comprehensive biochemical characterization of settlement stage leptocephalus larvae of bonefish (Albula vulpes).

Little is known about early development of the near-threatened bonefish (Albula vulpes), a member of superorder Elopomorpha. Members of Elopomorpha are partially defined by their synapomorphic leptocephalus larval stage, for which the nutritional requirements are not well understood. Characterizing the nutritional profile, including major nutrients (such as lipids) used for energetic processes, can help to gain a better understanding of the nutritional requirements for leptocephalus larvae. A total of 24 settlement stage A. vulpes leptocephalus larvae were collected at Long Caye Island, Belize. Samples were used to determine various biochemical characteristics including lipid class, fatty acid and glycosaminoglycan compositions. Each of these biochemical components plays a role in early developmental processes such as cellular membrane formation and is crucial for healthy development. Biochemical characteristics of settlement stage A. vulpes leptocephalus are presented in this study for the first time. The dominant lipid classes and fatty acids detected in these samples were consistent with prior studies using closely related species like the Japanese eel, indicating possible similarities in diets at this stage. In the future, similar analyses can be applied to other species that share the leptocephalus life stage to determine if nutritional requirements at this stage of development are unique to this species. The findings in this study will also help to facilitate the establishment of adequate aquaculture systems for captive bonefish, ultimately leading to improved management strategies for wild bonefish habitats.

Lipid Composition and Utilization in Early Stage Leptocephalus Larvae of Bonefish (Albula vulpes).

In order to encourage the survival of both captive and wild populations of bonefish (Albula vulpes), a deeper understanding of the species' early developmental characteristics is necessary. During ontogenesis, bonefish utilize lipids as a source of energy before the start of exogenous feeding. The goal of this study is to gain insight into the energetic needs of bonefish leptocephalus larvae in the post-hatch larval stage. Broodstock were collected in the wild and hormone induced. Spawning yielded eggs that were fertilized and were then incubated until hatching. Larval development was monitored throughout the duration of the trial until all larvae perished. Samples of larval tissue were taken to the lab for lipid analysis and composition was compared at different developmental stages. Larval lipid composition was significantly different across sample groups showing a change in lipid content related to development. After hatching, larvae gradually depleted wax esters-sterol ester (WE-SE) reserves over a period of 4 days, while simultaneously increasing hydrocarbon (HC). The role of WE-SE is seemingly tied to both buoyancy and energy reserves due to its high abundance immediately post-hatch and selective catabolism. As larvae weaned off of the nutrition provided by the yolk, exogenous feeding began to diversify lipid composition and overall lipid reserves were depleted. Future directions included the development of optimal larval feeds based on this analysis in order to gain more insight into the nutritional needs and requirements during the critical leptocephalus stages.

Induced spawning and embryonic and early larval development of bonefish (Albula vulpes).

Bonefish (Albula vulpes L.) are a highly prized sport fish. Despite their economic importance, populations in the Florida Keys and Caribbean are in decline, with the early life history undescribed. Injections of carp pituitary extract into A. vulpes during the advanced stages of ovarian development induced ovulation and spawning. Embryos were sampled hourly until hatching into undeveloped, yolk-sac leptocephalus larvae. These larvae survived 56 h post-hatch, when myomeres and eyes were developing but not the mouth. These results inform future research on the reproduction and early life history of A. vulpes.

Reproductive physiology of bonefishes (Albula spp.) across the Northwest Bahamas.

Bonefishes (Albula spp.) are classified within the superorder Elopomorpha, which is comprised of over 1000 species that share a unique leptocephalus larval stage. Bonefishes have a circum-tropical distribution, inhabiting inshore shallow water flats and gathering in presumptive nearshore pre-spawn aggregations (PSA) during spawning months. These fishes support economically important recreational fisheries and subsistence fisheries throughout their ranges, yet little is known regarding their reproductive biology. Analysis of oocyte development and nutrient composition, and sex and gonadotrophic hormone levels, was conducted on females sampled in Grand Bahama, Central Andros, and South Andros, The Bahamas, to assess their reproductive state. Fish collected from the flats habitats along all three islands exhibited four major reproductive phases (immature, developing, spawning capable, and regressing). In contrast, all females captured at presumptive PSA sites had eggs in the final stage of oocyte maturation, significantly higher levels of all reproductive hormones (17ß-estradiol, testosterone, and LH), larger vitellogenic oocytes, and oocytes exhibiting germinal vesicle migration and germinal vesicle breakdown. In addition, monthly variability in hormone levels and spawning readiness between Grand Bahama and Andros PSAs suggest that peak spawning times may differ among regions. Fatty acid and free amino acid composition and profiles, with high proportions of docosahexaenoic acid, histidine, and taurine, suggest that these nutrients are not only relevant as energy reserves, but also help achieve buoyancy and osmoregulation of oocytes. This study expands upon our understanding of fish reproductive and developmental physiology, and indicates potential factors influencing the survival and recruitment of bonefishes.