Monitoring of productive and biochemical parameters of young Clarias gariepinus during feeding of Skretting and Roycher AQUA feeds in experimental conditions

The article presents the results of monitoring the productive and biochemical indicators of the growth rate of young clary catfish using dry extruded complete feed for fish, which have proven to be best adapted for use at all stages of growing clary catfish, namely: Skretting and Roycher AQUA in experimental conditions. The research was conducted in the educational and experimental laboratories of Bila Tserkva National Agrarian University from 2019 to 2021. For the experiment, we used the young of the African marble clary catfish (Clarias gariepinus), purchased from one of the fish farms in the Odesa region. Clary catfish fry was kept in four rectangular plastic containers for 90 liters of freshwater. The tanks were two-thirds full (60 liters). The water temperature was maintained at 26 °C. For the experiment, 120 fries were used, which were kept in four plastic tanks by the method of analogs of 30 specimens each. Given that the fry differed in weight (for experiment 1 we selected fry with higher weight, and for experiment 2 – with lower weight), they were divided on the principle of analogs into two experimental and two control groups. Based on the results of monitoring in Experiment 1, fish observations, and mathematical calculation, we found that the feed ratio when fed Skretting and Roycher AQUA starter feed is 0.74 and 0.99 %, respectively. Based on the results of monitoring, fish observations, and mathematical calculation, it was found that the feed ratio in experiment 2 when feeding starter feed Skretting and Roycher AQUA is 0.75 and 1.54 %, respectively. The high feed rate for the use of Roycher AQUA can be explained by overuse due to the grinding of the granules. Growing aquaculture facilities in an artificially formed system – production, allows you to get environmentally friendly fish products all year round. This is a very important criterion in modern environmental conditions.

The distribution and relative abundance of the invasive Northern blue mussel, M. galloprovincialis, in New Zealand: management implications

<p>Biological invasions are a growing problem on a global scale, are capable of causing moderate to severe damage, and are most often associated with human activity. This is particularly true in the marine environment, where there are many well documented cases of non-indigenous species (NIS) spreading via maritime traffic or undergoing a range expansion associated with ocean temperatures continuing to increase. The blue mussel Mytilus galloprovincialis, recognized a one of the most successful NIS globally, is one such species that is spreading in such ways. However, in the Southern hemisphere research over the past decade has shown that there are two lineages of M. galloprovincialis present, likely different species, one native to the Northern hemisphere and one native to the Southern hemisphere. In New Zealand, the Northern lineage of M. galloprovincialis (MgN) has successfully invaded and poses a unique threat to native biodiversity as there are higher rates of introgression with the native Southern lineage of M. galloprovincialis (MgS) than elsewhere in the Southern hemisphere. However, whether MgN is causing other ecological damage in New Zealand is still unknown. Therefore, the main objective of Chapter 2 is to provide a preliminary description of the distribution and relative abundance of MgN in New Zealand, and how abiotic factors may be influencing this invasion. Also, it was recently reported that M. galloprovincialis causes severe economic losses to the native greenshell mussel Perna canaliculus aquaculture industry. However, these reports did not differentiate between the native and invasive blue mussel lineages. The main objective of Chapter 3 then is to provide a description of the distribution and relative abundance of MgN in the Marlborough Sounds, the primary P. canaliculus aquaculture region in New Zealand. The results of Chapter 2 indicate that several abiotic factors significantly influence the relative abundance of MgN across New Zealand; and that intranational maritime traffic is a more important vector of spread than international maritime traffic. The results of Chapter 3 show that the relative abundance of MgN was approximately equal across aquaculture facility sites and adjacent shore sites, but that increased habitat space on the grow-lines of aquaculture facilities has resulted in significantly increased overall abundances of both MgN and MgS. This means that there is a much larger MgN population in this region than would be otherwise present due to the aquaculture facilities. Overall, these results indicate that human activity in New Zealand is significantly affecting the MgN invasion therein. These findings are important for both management purposes and for guiding future research.</p>

The distribution and relative abundance of the invasive Northern blue mussel, M. galloprovincialis, in New Zealand: management implications

<p>Biological invasions are a growing problem on a global scale, are capable of causing moderate to severe damage, and are most often associated with human activity. This is particularly true in the marine environment, where there are many well documented cases of non-indigenous species (NIS) spreading via maritime traffic or undergoing a range expansion associated with ocean temperatures continuing to increase. The blue mussel Mytilus galloprovincialis, recognized a one of the most successful NIS globally, is one such species that is spreading in such ways. However, in the Southern hemisphere research over the past decade has shown that there are two lineages of M. galloprovincialis present, likely different species, one native to the Northern hemisphere and one native to the Southern hemisphere. In New Zealand, the Northern lineage of M. galloprovincialis (MgN) has successfully invaded and poses a unique threat to native biodiversity as there are higher rates of introgression with the native Southern lineage of M. galloprovincialis (MgS) than elsewhere in the Southern hemisphere. However, whether MgN is causing other ecological damage in New Zealand is still unknown. Therefore, the main objective of Chapter 2 is to provide a preliminary description of the distribution and relative abundance of MgN in New Zealand, and how abiotic factors may be influencing this invasion. Also, it was recently reported that M. galloprovincialis causes severe economic losses to the native greenshell mussel Perna canaliculus aquaculture industry. However, these reports did not differentiate between the native and invasive blue mussel lineages. The main objective of Chapter 3 then is to provide a description of the distribution and relative abundance of MgN in the Marlborough Sounds, the primary P. canaliculus aquaculture region in New Zealand. The results of Chapter 2 indicate that several abiotic factors significantly influence the relative abundance of MgN across New Zealand; and that intranational maritime traffic is a more important vector of spread than international maritime traffic. The results of Chapter 3 show that the relative abundance of MgN was approximately equal across aquaculture facility sites and adjacent shore sites, but that increased habitat space on the grow-lines of aquaculture facilities has resulted in significantly increased overall abundances of both MgN and MgS. This means that there is a much larger MgN population in this region than would be otherwise present due to the aquaculture facilities. Overall, these results indicate that human activity in New Zealand is significantly affecting the MgN invasion therein. These findings are important for both management purposes and for guiding future research.</p>

Dactylogyrus Infestation in Farmed Common Carp Cyprinus carpio from Aquaculture Facilities in Macedonia

A total of 958 specimens of farmed common carp Cyprinus carpio from eight of the most significant and largest cyprinid aquaculture facilities in Macedonia (pond and cage culture systems) were examined for parasitological investigation for three years. The following parasite species of the genus Dactylogyrus were identified: Dactylogyrus extensus, Dactylogyrus minutus and Dactylogyrus anchoratus. The highest prevalence was determined for D. extensus (38.8%), followed by D. minutus (7.9%) and D. anchoratus (2.8%). The highest mean intensity was determined for D. extensus (6.2), followed by D. minutus (4.7) and D. anchoratus (3.8). By seasons, the highest prevalence (16.5%) was recorded for D. extensus in winter, while the lowest (0.6%) for D. minutus in autumn. The highest mean intensity (8.0) was also determined for D. extensus in winter, and the lowest (1.9) for D. minutus in spring.

A fluorescent dissolved oxygen sensor with autocalibration based on ruthenium (II) tris-bathophenanthroline complex

The study describes a submersible fluorescent dissolved oxygen (DO) sensor suitable for aquaculture facilities. The sensor is based on the quenching of fluorescence from ruthenium (II) tris-bathophenanthroline complex, [Ru(dpp)3]2+. One of its precursors, bathophenanthroline (BPhen), was obtained by a green approach with less aggressive reagents than in a classical synthesis. It was embedded in a polymer membrane and attached to a glass window to fabricate a sensing element. The composition and functioning of the sensor are described. It uses an additional red LED for automatic calibration and correction of measurements due to photodegradation of Ru(dpp) over time. The intensity of the red light reflected from the active Ru(II) centres indicates their concentration and allows for automatic correction of the calibration factor. The sensor has demonstrated good linearity in calibration tests; its readings were independent of the presence of common inorganic ions in water, which might interfere with the results. This novel low-cost sensor with autocalibration is expected to be a long-term solution for aquaculture.

Molecular Investigation of Recurrent Streptococcus iniae Epizootics Affecting Coral Reef Fish on an Oceanic Island Suggests at Least Two Distinct Emergence Events

Streptococcus iniae is an emerging zoonotic pathogen of increasing concern for aquaculture and has caused several epizootics in reef fishes from the Caribbean, the Red Sea and the Indian Ocean. To study the population structure, introduction pathways and evolution of S. iniae over recurring epizootics on Reunion Island, we developed and validated a Multi Locus Sequence Typing (MLST) panel using genomic data obtained from 89 isolates sampled during epizootics occurring over the past 40years in Australia, Asia, the United States, Israel and Reunion Island. We selected eight housekeeping loci, which resulted in the greatest variation across the main S. iniae phylogenetic clades highlighted by the whole genomic dataset. We then applied the developed MLST to investigate the origin of S. iniae responsible for four epizootics on Reunion Island, first in inland aquaculture and then on the reefs from 1996 to 2014. Results suggest at least two independent S. iniae emergence events occurred on the island. Molecular data support that the first epizootic resulted from an introduction, with inland freshwater aquaculture facilities acting as a stepping-stone. Such an event may have been facilitated by the ecological flexibility of S. iniae, able to survive in both fresh and marine waters and the ability of the pathogen to infect multiple host species. By contrast, the second epizootic was associated with a distinct ST of cosmopolitan distribution that may have emerged as a result of environment disturbance. This novel tool will be effective at investigating recurrent epizootics occurring within a given environment or country that is despite the fact that S. iniae appears to have low genetic diversity within its lineage.

One in a Million: Genetic Diversity and Conservation of the Reference Crassostrea angulata Population in Europe from the Sado Estuary (Portugal)

The production of cupped oysters is an important component of European aquaculture. Most of the production relies on the cultivation of the Pacific oyster Crassostrea gigas, although the Portuguese oyster Crassostrea angulata represents a valuable product with both cultural and economic relevance, especially in Portugal. The authors of the present study investigated the genetic diversity of Portuguese oyster populations of the Sado estuary, both from natural oyster beds and aquaculture facilities, through cox1 gene fragment sequencing. Then, a comparison with a wide dataset of cupped oyster sequences obtained from GenBank (up to now the widest available dataset in literature for the Portuguese oyster) was performed. Genetic data obtained from this work confirmed that the Pacific oyster does not occur in the natural oyster beds of the Sado estuary but showed that the species occasionally occurs in the oyster hatcheries. Moreover, the results showed that despite the founder effect and the bottleneck events that the Sado populations have experienced, they still exhibit high haplotype diversity. Risks are arising for the conservation of the Portuguese oyster reference populations of the Sado estuary due to the occurrence of the Pacific oyster in the local hatcheries. Therefore, researchers, local authorities, and oyster producers should work together to avoid the loss of this valuable resource.

Non-Indigenous Species on Artificial Coastal Environments: Experimental Comparison between Aquaculture Farms and Recreational Marinas

Globally, there is growing concern regarding the effects of the increasing anthropogenic pressures in marine communities. Artificial structures such as marinas and aquaculture facilities serve as invasion hotspots; hence, monitoring fouling communities on these structures can be valuable for detecting new invasions. In the current study, 24 settlement PVC plates were deployed for three months to compare the recruitment ability of these two artificial environments along the south coast of the offshore island of Madeira (NE Atlantic). The results showed higher variations in the species richness between regions (SW vs. SE) than between artificial habitats (sea-cages vs. marinas), although the community composition differed. Cnidaria and Bryozoa were the most representative groups in the aquaculture systems, while Bryozoa and Chordata were in the marinas. A sum of 18 NIS was recorded for the study, accounting for between 21.88% and 54.84% of the total number of species in the aquaculture facilities and marinas, respectively. The higher NIS percentage from the marinas was even more explicit in the SE coast, where Cradoscrupocellaria bertholletii, Parasmittina alba, and Botrylloides niger distinctly dominated fouling populations. The results suggest that at least some particular NIS previously reported in the studied marinas successfully colonized sea-cages. Future assessments need to address the potential role of aquaculture facilities as drivers for the secondary spread of NIS. Additionally, two new records are considered for Madeira: Eudendrium capillare and Ericthonius punctatus.