Multiple Indicators of Wastewater Contamination to Shellfish Farms Near a Tidal River

Wastewater contamination threatens the shellfish aquaculture industry by posing risks to public health. Multiple indicators of wastewater contamination, including fecal coliforms (fc), male-specific coliphage (MSC), dissolved nutrients, stable isotope ratios, and artificial sweeteners were analyzed to determine possible sources of wastewater to local shellfish farms. Samples were collected at a wastewater treatment plant outfall (WTPO), nonpoint residential, and agricultural areas of a tidal river, and tidal creek inflows adjacent to farms. To capture seasonal variation, we sampled under warm and cold, and wet and dry conditions. Fc ranged < 5–5250 CFU 100 mL−1, NH4+ concentrations ranged up to 9.58 μM, and δ15N ranged 1.4–7.8‰ across all sites and time periods. Fc and NH4+ were higher, and δ15N was lower in the cold wet period and near residential and agricultural areas. Acesulfame and sucralose concentrations ranged 0.004–0.05 μg L−1 and up to > 0.8 μg L−1, respectively, and did not correlate with other indicators but tended to be higher in residential areas and at the WTPO, supporting their value in differentiating human sewage from other sources. Shoreline disturbance during septic system upgrades may have inadvertently contributed bacterial indicators to shellfish farms. Overall, indicator source dominance depended on environmental conditions, with WTPO and residential sources conveying human-specific indicators to farms year-round, while agricultural and industrial sites contributed additional fc during cold wet periods. The use of multiple indicators will aid managers to detect and define wastewater sources, identify targets for monitoring or remediation, and manage shellfish areas in estuaries with a mosaic of land-derived wastewater sources.

Studies on Animals Closely Associated with Some New Zealand Marine Shellfish

<p>Between March 1973 and September 1974, 858 Perna canaliculus (Gmelin), 150 Mytilus edulis aoteanus Powell, 237 Crassostrea qlomerata (Gould) and 153 Ostrea lutaria Hutton, were surveyed for parasites. From these four commercially important shellfish species, a total of two sporozoans, three species of trematode sporocyst, and a copepod were found. A second copepod and pea-crabs were found associated with certain of the shellfish, but the nature of this association is uncertain. During the examination of each shellfish the ratio of the meat volume to internal shell volume was measured. This provided a condition factor for the shellfish, and gave an indication of the effect of the parasite on the meat weight of the bivalve. Perna canaliculus was collected from Ahipara, Wellington Harbour, and the Marlborough Sounds. Spores of a gregarine, Nematopsis sp., were abundant in the Ahipara mussels, common in Wellington and rare in the Sounds. The fellodistomid trematode sporocyst known as Cercaria haswelli Dollfus was found in mussels from all three locations. Laboratory infection experiments established that the cercaria from this sporocyst develops into the trematode Terqestia aqnostomi (manter). Gravid specimens of this trematode were obtained for the first time, from the mullet Aldrichetta forsteri Cuvier & Valanciennes. Two specimens of the bucephalid sporocyst described by Haswell (1903) were recovered and re-described. The copepods pseudomyicola spinosus Raffaele & Monticelli and Lichomolgus.n sp. were associated with the mussels, but their status is uncertain. The post-planktonic stages of the pea-crab Pinnotheres novaezelandiae Filhol are described for the first time, and the seasonal abundance, effect of depth on abundance, and the effect of the crab on the host's condition are described. Differences between the zoea of apparently identical female crabs from different host species are noted and the significance of these is discussed. Because of the difference between the zoea of crabs from P. canaliculus and Atrina zelandica Gray, only the crabs from the former host are refered to as P. novaezelandiae. The pea-crabs found in A. zelandica, C. glomerata, and M. edulis aoteanus, have not been assigned to a species. Mytilus edulis aoteanus is host to Tergestia aqnostomi sporocysts, Pseudomyicola spinosus, and Pinnotheres sp. Crassostrea glomerata was collected from the Bay of Islands. Only one parasite, the copepod Pseudomyicola spinosus, was found in this host. A pea-crab Pinnotheres sp. is occasionally found associated with the oyster. A disease of this oyster, a symptom of which is the formation of necrotic pustules in the adductor mussel, could not be traced to any parasite. This disease is discussed in an appendix. Ostra lutaria was obtained from Wellington Harbour, the Marlborough Sounds, and Foveaux Strait. Sporozoan cysts were found to occur in 10% of the oysters from Foveaux Strait, but were not observed to adversly affect the oyster. The sporocysts of the trematode Bucephalus longicornutus (Manter) occur in the areas sampled. Pseudomyicola spinosus lnfests the oyster in Wellington and in the Sounds, but not in Foveaux Strait. It was concluded that there were no serious pathogens likely to infect the shellfish farms growing these species, and that there was little farmers could do at present to reduce the effect on the host of the symbionts already present in the shellfish beds. A checklist and bibliography of all the parasites infecting New Zealand marine molluscs is included is an appendix.</p>

Studies on Animals Closely Associated with Some New Zealand Marine Shellfish

<p>Between March 1973 and September 1974, 858 Perna canaliculus (Gmelin), 150 Mytilus edulis aoteanus Powell, 237 Crassostrea qlomerata (Gould) and 153 Ostrea lutaria Hutton, were surveyed for parasites. From these four commercially important shellfish species, a total of two sporozoans, three species of trematode sporocyst, and a copepod were found. A second copepod and pea-crabs were found associated with certain of the shellfish, but the nature of this association is uncertain. During the examination of each shellfish the ratio of the meat volume to internal shell volume was measured. This provided a condition factor for the shellfish, and gave an indication of the effect of the parasite on the meat weight of the bivalve. Perna canaliculus was collected from Ahipara, Wellington Harbour, and the Marlborough Sounds. Spores of a gregarine, Nematopsis sp., were abundant in the Ahipara mussels, common in Wellington and rare in the Sounds. The fellodistomid trematode sporocyst known as Cercaria haswelli Dollfus was found in mussels from all three locations. Laboratory infection experiments established that the cercaria from this sporocyst develops into the trematode Terqestia aqnostomi (manter). Gravid specimens of this trematode were obtained for the first time, from the mullet Aldrichetta forsteri Cuvier & Valanciennes. Two specimens of the bucephalid sporocyst described by Haswell (1903) were recovered and re-described. The copepods pseudomyicola spinosus Raffaele & Monticelli and Lichomolgus.n sp. were associated with the mussels, but their status is uncertain. The post-planktonic stages of the pea-crab Pinnotheres novaezelandiae Filhol are described for the first time, and the seasonal abundance, effect of depth on abundance, and the effect of the crab on the host's condition are described. Differences between the zoea of apparently identical female crabs from different host species are noted and the significance of these is discussed. Because of the difference between the zoea of crabs from P. canaliculus and Atrina zelandica Gray, only the crabs from the former host are refered to as P. novaezelandiae. The pea-crabs found in A. zelandica, C. glomerata, and M. edulis aoteanus, have not been assigned to a species. Mytilus edulis aoteanus is host to Tergestia aqnostomi sporocysts, Pseudomyicola spinosus, and Pinnotheres sp. Crassostrea glomerata was collected from the Bay of Islands. Only one parasite, the copepod Pseudomyicola spinosus, was found in this host. A pea-crab Pinnotheres sp. is occasionally found associated with the oyster. A disease of this oyster, a symptom of which is the formation of necrotic pustules in the adductor mussel, could not be traced to any parasite. This disease is discussed in an appendix. Ostra lutaria was obtained from Wellington Harbour, the Marlborough Sounds, and Foveaux Strait. Sporozoan cysts were found to occur in 10% of the oysters from Foveaux Strait, but were not observed to adversly affect the oyster. The sporocysts of the trematode Bucephalus longicornutus (Manter) occur in the areas sampled. Pseudomyicola spinosus lnfests the oyster in Wellington and in the Sounds, but not in Foveaux Strait. It was concluded that there were no serious pathogens likely to infect the shellfish farms growing these species, and that there was little farmers could do at present to reduce the effect on the host of the symbionts already present in the shellfish beds. A checklist and bibliography of all the parasites infecting New Zealand marine molluscs is included is an appendix.</p>

Prospects for the development of aquaculture in the southern regions of Russia

The article presents an analysis of the prospects for the development of aquaculture in the southern regions of Russia. It is shown that the volume of aquaculture in the southern regions of the country in 2020 amounted to more than 78.6 thousand tons, which is 24% of the all-Russian. The Southern Federal District is one of the three leaders in the production of aquaculture products, its volume amounted to 81.4 thousand tons in 2019 and 70.2 thousand tons in 2020. About 90.6% of aquaculture products were received in the Rostov and Astrakhan regions, Krasnodar Krai. The volume of commercial production in the Republic of Crimea has increased significantly (by 23%). Pasture aquaculture, pond and industrial fish farming, recreational aquaculture, and mariculture are promising areas in the federal District. There is a great variety of growing objects, these are both traditional species for the region and the country — carp, herbivorous, sturgeon, and pike, common and channel catfish, walleye, perch, pilengas, paddlefish, buffalo. In addition, shellfish farms are actively developing on the coast of Crimea. The prospects of interaction between fundamental, branch, university science and enterprises of the real sector of the economy are shown. In order to achieve sustainable development of the country’s aquaculture, it is necessary to strengthen state support measures, especially for small businesses and fish farming. At the same time, support should be provided not only at the state, but also at the regional level.

Eutrophication Driven by Aquaculture Fish Farms Controls Phytoplankton and Dinoflagellate Cyst Abundance in the Southern Coastal Waters of Korea

We examined the dynamics of dinoflagellate cyst and phytoplankton assemblages in eutrophic coastal waters of Korea, adjacent to fish and shellfish farms. Water temperature showed seasonality, whereas salinity and pH remained relatively consistent. Dissolved inorganic nutrient levels were higher in September and at the inner stations, where aquaculture fish farms are located than those in May and at the outer stations. Canonical correspondence analysis and artificial neural network analysis revealed multiple environmental factors that affect the distribution of phytoplankton and dinoflagellate cysts. Diatoms dominated in the phytoplankton assemblages, while the protoperidinioid group dominated in the dinoflagellate cyst assemblages. Cyst abundance was higher at the outer stations than at the inner stations due to transport by fast currents, and phytoplankton abundance was positively correlated with cyst abundance. An increase in diatom abundance led to an increase in heterotrophic/mixotrophic cyst abundance, indicating that excessive uneaten food and urinary waste from the fish farms caused eutrophication in the study region and fast growth of diatoms, thereby contributing to the growth of heterotrophic/mixotrophic dinoflagellates and consequently, high abundance of heterotrophic/mixotrophic dinoflagellate cysts.

Impact of 24-hour hypoxia on hemocyte functions of Anadara kagoshimensis (Tokunaga, 1906)

Shellfish farms are usually located in coastal areas, where molluscs can be exposed to hypoxia. Cultivating at low oxygen levels causes general disruptions of growth rate, outbreaks of diseases, and mollusc mortality. Impact of short-term hypoxia on hemocyte functions of ark clam (Anadara kagoshimensis) was investigated by flow cytometry. A control group was incubated at 6.7–6.8 mg O2·L−1, an experimental one – at 0.4–0.5 mg O2·L−1. Exposition lasted for 24 hours. Hypoxia was created by blowing seawater in shellfish tanks with nitrogen gas. In ark clam hemolymph, 2 groups of hemocytes were identified on the basis of arbitrary size and arbitrary granularity: granulocytes (erythrocytes) and agranulocytes (amebocytes). Erythrocytes were the predominant cell type in A. kagoshimensis hemolymph, amounting for more than 90 %. No significant changes in cellular composition of ark clam hemolymph were observed. The production of reactive oxygen species and hemocyte mortality in the experimental group also remained at control level. The results of this work indicate ark clam tolerance to hypoxia.

Prevalence of Vibrio parahaemolyticus Causing Acute Hepatopancreatic Necrosis Disease of Shrimp in Shrimp, Molluscan Shellfish and Water Samples in the Mekong Delta, Vietnam

A total of 481 samples, including 417 shrimp and molluscan shellfish samples from retail shops and farms and 64 water samples from shrimp and molluscan shellfish farms in the Mekong Delta located the southern part of Vietnam, were examined for the presence of Vibrio parahaemolyticus (VpAHPND) caused acute haepatopancreatic necrosic disease (AHPND) in shrimp. VpAHPND strains were isolated in two of 298 (0.7%) molluscan shellfish samples from retail shops, seven of 71 (9.9%) shrimp samples from shrimp ponds, and two of 42 (4.8%) water samples from shrimp ponds. VpAHPND strains were classified into two types of O antigen, including O1 and O3, in which O1 was the predominant. VpAHPND strains isolated showed high resistance rates to colistin (100%), ampicillin (93.8%), and streptomycin (87.5%). These results indicate that VpAHPND is widely prevalent in environment in the Mekong Delta, Vietnam.