Anthropogenic Microparticles in Aquaculture and Wild Fish: A Case Study of Three Commercially Important Species in the Eastern Mediterranean

Hatchery‐produced anadromous salmonids often differ from their wild conspecifics in behavior, growth, and survival after release, but our understanding of their comparative ecology at sea is very limited. We used stable isotopes of carbon and nitrogen to test the null hypothesis that hatchery‐produced steelhead Oncorhynchus mykiss from Forks Creek in southwestern Washington would be similar in trophic level and marine distribution to wild fish from the same river. Analysis of scale samples from 30 fish of each type that had migrated to sea in 2001 and 2002 (120 fish in all) revealed significant effects of year and origin on both C and N. The values for δ15N were consistent with a higher trophic level for the wild fish (mean = 10.82, SD = 0.57) than for the hatchery fish (mean = 10.51, SD = 0.59), and the δ13C values were consistent with more reliance on nearshore sources of C by wild fish (wild fish mean = −16.52, SD = 0.30; hatchery fish mean = −16.73, SD = 0.31). The wild fish showed no relationship between body size and isotope values, but among the hatchery fish larger individuals tended to have lower δ15N values and more negative δ13C values. The wild fish were, on average, larger than the hatchery fish but had higher δ15N values and less negative δ13C values. These patterns are the opposite of what would be expected from a difference in growth rate, suggesting that the differences arose from ecological processes rather than a size or growth effect. Interactions between trophic level and location prevent a determination of which features of the marine ecology differed between wild and hatchery fish, but either factor could result from differences in the genetic background and rearing history of wild and hatchery fish and could contribute to differences in their performance (growth and survival) at sea.

The current epidemiological situation of viral nervous necrosis virus (VNNV) on Hainan Island was investigated. A total of 490 hatchery-reared fish and 652 wild fish were sampled for VNNV detection from March 2013 to May 2014. Positive detection rates of 84.53% (153/181) and 0.97 % (3/309) were obtained in diseased and healthy hatchery-reared samples, respectively, by conventional RT-PCR. However, using more-sensitive nested RT-PCR, the positive detection rates in healthy hatchery-reared fish reached up to 64.08% (198/309), suggesting that asymptomatic VNNV carriers commonly exist among larvae and juveniles breeding on Hainan Island. In wild-fish samples, 2.6% (17/652) and 34.2% (223/652) positive detection rates were observed using RT-PCR and nested RT-PCR, respectively, indicating that wild fish may be a potential reservoir for VNNV. Phylogenetic analysis showed that all 52 VNNV isolates from cultured fish belong to the RGNNV genotype, but 2 out of 48 VNNV isolates from wild fish samples were found to be of the SJNNV genotype. This study is the first to confirm the existence of SJNNV-genotype VNNV in China. Golden pompano, an important fish species for culture, was selected as a fish model to investigate the optimal conditions for RGNNV disease progression in artificial infection experiments. The effects of temperature, salinity, and fish size were evaluated. Results showed that 28 °C and 20 ‰ are the optimal infection temperature and salinity, respectively, and golden pompano juveniles with small body sizes are more susceptible to RGNNV. These findings are highly consistent with those conditions involved in the natural outbreak of RGNNV.

Several studies have examined the reproducibility over time of standard clinical measurements of pulmonary airways parameters, such as FEV1 and FVC. These studies indicate fairly consistent reproducibility of such measurements over periods of months and years. Although such traditional pulmonary function tests can provide quantitative measures of lung function, they do not provide any insight into the local or regional variation of individual airways. Therefore, in a longitudinal study in dogs, we directly measured the baseline size (cross-sectional area) of the same individual canine airways multiple times over a 1-yr period, using high-resolution computed tomography (HRCT). We compared the variability of individual airway size both within and between subjects to the various sizes of airways and to seasonal differences in size. Five anesthetized, intubated, and ventilated dogs were studied between five and eight times over a 15-mo period. HRCT scans were acquired at end expiration with the dogs at FRC on all occasions. All individual airways showed considerable variability in size over time as measured by the coefficient of variation (CV) (range: 9.2 to 69.3). The sizes of individual airways within a dog were seen to change by as much as twofold over time. Some dogs also showed significantly greater overall variability in airway size than did other dogs (p < 0.01), but this variability was related neither to the size of the airway (p = 0.34) nor to the season. These findings indicate a substantial local and regional variability in airway caliber that would not be detectable with conventional pulmonary function tests. This variability in airway size could contribute to the local pathogenesis of lung disease.

Naturally occurring elemental signatures (or composition) of otoliths may enable aquaculture and wild-caught yellowtail kingfish (Seriola lalandi) to be distinguished from one another, so that in the event of aquaculture escapes, escaped fish could be identified. Yellowtail kingfish were obtained from aquaculture ventures in three regions of Spencer Gulf and from nine areas external to aquaculture throughout the inner and outer Spencer Gulf, South Australia. Elemental signatures (Mg, Mn, Sr, Ba) of otoliths were analysed via LA-ICP-MS (laser ablation-inductively coupled plasma-mass spectrometry). A highly significant difference was detected between elemental signatures of the aquaculture and wild-caught fish, but this difference was largely attributable to wild fish from Port Augusta being different from the other groupings. For individual elements, it was difficult to detect differences between aquaculture and wild-caught fish, as there was considerable variation between locations within each group. When comparisons between aquaculture and wild fish were made of the inner and outer Spencer Gulf, aquaculture fish could be distinguished from wild fish and classified correctly with a high degree of accuracy (82–100%); the same level of accuracy was not achieved with wild fish. Comparison of elemental transects showed considerable variability between locations, with no features distinguishing aquaculture or wild-caught fish. It would be beneficial to combine naturally occurring signatures with other identification approaches (e.g. artificial elemental signatures) to accurately distinguish aquaculture from wild-caught fish. The impacts of escaped fish could then be determined.

Recent advances in sequencing methods have greatly expanded the knowledge of teleost-associated microorganisms. While fish-gut microbiomes are comparatively well studied, less attention has gone toward other, external organ-microbiome associations. Gills are particularly interesting to investigate due to their functions in gas exchange, osmoregulation, and nitrogen excretion. We recently discovered a branchial symbiosis between nitrogen-cycling bacteria and teleosts (zebrafish and carp), in which ammonia-oxidizing Nitrosomonas and denitrifying bacteria together convert toxic ammonia excreted by the fish into harmless dinitrogen (N2) gas. This symbiosis can function as a "natural biofilter" in fish gills and can potentially occur in all ammonotelic fish species, but it remains unknown how widespread this symbiosis is. In this study, we analyzed all publicly available gill microbiome data sets and checked for the presence of Nitrosomonas. We discovered that more than half of the described fish gill microbiomes contain 16S rRNA gene sequences of ammonia-oxidizing bacteria (AOB). The presence of gill-specific AOB was shown in both wild and aquacultured fish, as well as in marine and freshwater fish species. Based on these findings, we propose that ammonia oxidizers are widespread in teleost fish gills. These gill-associated AOB can significantly affect fish nitrogen excretion, and the widespread nature of this association suggests that the gill-associated AOB can have similar impacts on more fish species. Future research should address the contribution of these microorganisms to fish nitrogen metabolism and the fundamental characteristics of this novel symbiosis.IMPORTANCERecent advances in sequencing have increased our knowledge of teleost-associated microbiota, but the gill microbiome has received comparatively little attention. We recently discovered a consortium of nitrogen-cycling bacteria in the gills of common carp and zebrafish, which are able to convert (toxic) ammonia into harmless dinitrogen gas. These microorganisms thus function as a natural nitrogen biofilter. We analyzed all available gill microbiome data sets to determine how widespread gill-associated ammonia-oxidizing bacteria (AOB) are. More than half of the data sets contained AOB, representing both aquacultured and wild fish from freshwater and marine habitats. In total, 182 amplicon sequencing variants were obtained, of which 115 were found specifically in the gills and not the environmental microbiomes. As gill-associated AOB are apparently widespread in teleost fish, it is important to study their impact on host nitrogen excretion and the potential to reduce ammonia accumulation in (recirculating) aquaculture of relevant fish species.

Several studies have examined the reproducibility over time of standard clinical measurements of pulmonary airways parameters, such as FEV1 and FVC. These studies indicate fairly consistent reproducibility of such measurements over periods of months and years. Although such traditional pulmonary function tests can provide quantitative measures of lung function, they do not provide any insight into the local or regional variation of individual airways. Therefore, in a longitudinal study in dogs, we directly measured the baseline size (cross-sectional area) of the same individual canine airways multiple times over a 1-yr period, using high-resolution computed tomography (HRCT). We compared the variability of individual airway size both within and between subjects to the various sizes of airways and to seasonal differences in size. Five anesthetized, intubated, and ventilated dogs were studied between five and eight times over a 15-mo period. HRCT scans were acquired at end expiration with the dogs at FRC on all occasions. All individual airways showed considerable variability in size over time as measured by the coefficient of variation (CV) (range: 9.2 to 69.3). The sizes of individual airways within a dog were seen to change by as much as twofold over time. Some dogs also showed significantly greater overall variability in airway size than did other dogs (p < 0.01), but this variability was related neither to the size of the airway (p = 0.34) nor to the season. These findings indicate a substantial local and regional variability in airway caliber that would not be detectable with conventional pulmonary function tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Simple SummaryThis study was focused on differences in microbial varieties in common carp living in two different environments: open fish ponds and in nature. The results demonstrated that wild fish carry more than 2.5 times the bacterial species in their gut compared with aquacultured fish. More than 400 species of bacteria were identified, the majority of which are considered beneficial microbiota. Besides bacterial variety, it was determined that aquacultured fish harbored more bacteria that are treated as pathogens in animals and humans. The frequency of antimicrobial resistance in bacterial indicators was more common in aquacultured fish compared with bacteria from a wild population, therefore fish farming can be treated as a potential source of environmental contamination with antimicrobial resistant bacteria.In this study we analyzed differences in microbial composition and antimicrobial resistance profiles in common carp living in two different environments: fish ponds, where carp have been kept under the same growing conditions over the last 50 years, and from the wild. The results demonstrated that wild fish carry a great variety of bacterial species (448 species with a prevalence of at least 0.01% from the total number of reads). Aquacultured individuals harbored 2.56 times fewer species in their gut. Significant microbial differences were observed in all taxonomic ranks, including bacterial classes and phyla. Besides bacterial variety, it was determined that aquacultured fish harbored more bacteria that are considered pathogens or opportunistic pathogens, such as Moraxellaceae, Flavobacteriaceae, and Staphylococcaceae. The frequency of antimicrobial resistance in bacterial indicators was more common in aquacultured fish than in wild fish, therefore fish farming may be a potential source of environmental contamination with antimicrobial resistant bacteria.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 181:81-96 (1999) - doi:10.3354/meps181081 Gradients in coral reef fish density and size across the Barbados Marine Reserve boundary: effects of reserve protection and habitat characteristics Matthew R. Chapman, Donald L. Kramer* Department of Biology, McGill University, 1205 Docteur Penfield Ave., Montréal, Quebec H3A 1B1, Canada *E-mail: don_kramer@maclan.mcgill.ca ABSTRACT: Reductions in fishing mortality within no-take coral reef marine reserves can produce gradients in the density and size of fishes across reserve boundaries. Such gradients may be affected by other factors, however, including differences in habitat quality between reserve and non-reserve areas and the movement of fish across reserve boundaries. To examine the effects of protection from fishing mortality and of habitat quality on an assemblage of exploited reef fishes, we measured the spatial patterns of fish density and size on fringing reefs near the boundary of the Barbados Marine Reserve (Barbados, West Indies) and statistically controlled for habitat correlates of fish density and size. Reserve sites supported a higher total density and size of fishes than non-reserve sites. Most species had a non-significantly higher mean density and size at reserve sites. The density and/or size of many species were correlated with the depth, rugosity, and/or substrate composition of sites. After statistically controlling for the effects of habitat correlates, the difference in total density between reserve and non-reserve sites remained significant, and the mean density and size of most species remained non-significantly higher at reserve sites. Neither the mobility of species nor their vulnerability to capture by Antillean fish traps was correlated with their relative difference in density or size between reserve and non-reserve sites. Spearfishing target species had a significantly higher relative difference in size between reserve and non-reserve sites than non-target species. Protection from fishing mortality and higher habitat quality appear to contribute to the increased density and size of fishes on study reefs in the Barbados Marine Reserve, and this difference is not compromised by emigration from the reserve. KEY WORDS: Marine protected area · Harvest refugia · Mobility · Spillover Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 181. Publication date: May 18, 1999 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1999 Inter-Research.

The presence of endocrine-disrupting chemicals (EDCs) in aquatic environments such as water, sediment, and sludge received more and more attention. However, the bioaccumulate properties of EDCs, particularly progestins and androgens, in various tissues of different wild freshwater fish species, as well as their effects on human health, have not been fully studied. The muscle, liver, and gills of three wild fish species obtained from the East Dongting Lake in southern China were examined for the presence of 19 EDCs (4 progestins, 5 androgens, 6 estrogens, and 4 phenols). Seventeen analytes were detected in all fish samples, and the concentrations of progestins, androgens, estrogens, and phenols ranged from ND-78.80 ng/g (wet weight, ww), ND-50.40 ng/g ww, ND-3573.82 ng/g ww, and ND-88.17 ng/g ww, respectively. The bioaccumulation of some EDCs in wild fish from East Dongting Lake was species-specific. Additionally, AND, EES, P4, and E2 were discovered in the liver at higher levels than in the muscle, suggesting that livers had a larger ability for enriching these EDCs than the muscle. Furthermore, the relationships between the fish sizes and the EDC concentrations indicated that total weight and length had a negligible impact on the bioaccumulation of EDCs in various fish species. Most importantly, the effects of EDCs on human health as a result of fish consumption were assessed. Although the estimated daily intakes (EDIs) of most EDCs were much lower compared with the corresponding acceptable daily intakes (ADIs) via consuming fish collected in this study, the EDI of EE2 in Silurus asotus was higher than the ADI of E2, indicating that Silurus asotus from East Dongting Lake should be eaten in moderation by local residents.

Are regional fisheries’ catches changing with climate?

No increase in marine microplastic concentration over the last three decades – A case study from the Baltic Sea

Atrial natriuretic peptide levels and heart morphology in migrating Atlantic salmon (Salmo salar) smolts from 4 rivers with different environmental conditions

The competitive interactions between hatchery and wild juvenile white‐spotted charr Salvelinus leucomaenis were examined in enclosure experiments in a natural stream. A total of 24 enclosures (1·0 × 1·0 × 0·7 m height) were arranged in stream in an array for randomized block design with replicates of three treatments (wild fish only, hatchery fish only, wild plus hatchery fish). Three experiments were conducted in 2006, using different densities and sizes for each experimental trial. When densities in enclosures were controlled to be equal among treatments (4 individuals m−2: substitutive design), wild fish in the presence of hatchery fish had significantly higher growth rates than the wild fish alone treatment. When densities in enclosures were controlled to be 4 individuals m−2 hatchery fish only treatment, 4 individuals m−2 wild fish only treatment and 8 individuals m−2 in the hatchery plus wild fish treatment (additive design), wild fish in the presence of hatchery fish had significantly lower growth rate than the wild fish alone treatment. Hatchery fish in the presence of wild fish also grew significantly slower than the hatchery fish alone treatment. When densities in enclosures were controlled to be equal among treatments (4 individuals m−2) but hatchery fish were 1·1 times longer than wild fish, growth of wild fish in the presence of the larger hatchery fish did not differ significantly from growth of the wild fish alone treatment. These results suggested that relative size of hatchery fish in relation to wild fish and increased fish density are two important factors influencing the growth of wild juvenile S. leucomaenis.

The principal species of marine aquaculture in Europe are Atlantic salmon (Salmo salar), sea bass (Dicentrarchus labrax) and sea bream (Sparus auratus). For Atlantic salmon and sea bass, a substantial part of total genetic variation is partitioned at the geographical population level. In the case of sea bream, gene flow across the Azores/Mediterranean scale appears to be extensive and population structuring is not detected. For Atlantic salmon and sea bass, natural population structure is at risk from genetic interaction with escaped aquaculture conspecifics. The locally adaptive features of populations are at risk from interbreeding with non-local aquaculture fish. Wild populations, generally, are at risk from interactions with aquaculture fish that have been subject to artificial selection or domestication. Atlantic salmon is the main European aquaculture species and its population genetics and ecology have been well-studied. A general case regarding genetic interactions can be based on the information available for salmon and extended to cover other species, in the appropriate context. A generalized flow chart for interactions is presented. Salmon escape from aquaculture at all life stages, and some survive to breed among wild salmon. Reproductive fitness in the escaped fish is lower than in native, wild fish because of behavioural deficiencies at spawning. However, as the number of salmon in aquaculture greatly exceeds the number of wild fish, even small fractional rates of escape may result in the local presence of large numbers, and high frequencies, of escaped fish. At present, policy and legislation in relation to minimizing genetic interactions between wild and aquaculture fish is best developed for Atlantic salmon, through the recommendations of the Oslo Agreement developed by the North Atlantic Salmon Conservation Organization and subsequent agreements on their implementation. In future, the potential use of genetically modified fish in aquaculture will make additional policy development necessary. Improved containment is recommended as the key to minimizing the numbers and therefore the effects of escaped fish. Emergency recovery procedures are recommended as a back-up measure in the case of containment failure. Reproductive sterility is recommended as a future key to eliminating the genetic potential of escaped fish. The maintenance of robust populations of wild fish is recommended as a key to minimizing the effects of escaped fish on wild populations.

ABSTRACTMore than 1000 spores from 11 species of red algae were collected; their differences in size and sinking rates were measured using a new micro‐video technique. A relationship between size and sinking rate was shown with larger spores generally sinking faster than smaller ones. Variability in spore size, or lack thereof, is a species characteristic. Cryptopleura violacea (J. G. Ag.) Kylin and Neoagardhiella baileyi (Kutz.) Wynne and Taylor were found to produce a wide range of spore sizes. Such variability in size may be related to differences in spore formation. Centrifugation was used to separate the contents of spores to show differences in them. The ecological implications of these observations are considered.