­Blue mussel (Mytilus spp.) cultivation in mesohaline eutrophied inner coastal waters: mitigation potential, threats and cost effectiveness

The EU-water framework directive (WFD) focuses on nutrient reductions to return coastal waters to the good ecological status. As of today, many coastal waters have reached a steady state of insufficient water quality due to continuous external nutrient inputs and internal loadings. This study focuses first on the current environmental status of mesohaline inner coastal waters to illustrate their needs of internal measures to reach demanded nutrient reductions and secondly, if mussel cultivation can be a suitable strategy to improve water quality. Therefore, nitrogen, phosphorus, chlorophyll a, and Secchi depth of nine mesohaline inner coastal waters in north east Germany were analyzed from 1990 to 2018. Two pilot mussel farms were used to evaluate their effectiveness as a mitigation measure and to estimate potential environmental risks, including the interactions with pathogenic vibrio bacteria. Further, estimated production and mitigation potential were used to assess economic profitability based on the sale of small sized mussels for animal feed and a compensation for nutrient mitigation. The compensation costs were derived from nutrient removal costs of a waste water treatment plant (WWTP). Results show that currently all nine water bodies do not reach the nutrient thresholds demanded by the WFD. However, coastal waters differ in nutrient pollution, indicating that some can reach the desired threshold values if internal measures are applied. The mitigation potential of mussel cultivation depends on the amount of biomass that is cultivated and harvested. However, since mussel growth is closely coupled to the salinity level, mussel cultivation in low saline environments leads to lower biomass production and inevitably to larger cultivation areas. If 50% of the case study area Greifswald Bay was covered with mussel farms the resulting nitrogen reduction would increase Secchi depth by 7.8 cm. However, high chlorophyll a values can hamper clearance rates (<20 mg m−3 = 0.43 l h−1 dry weight g−1) and therefore the mitigation potential. Also, the risk of mussel stock loss due to high summer water temperatures might affect the mitigation potential. The pilot farms had no significant effect on the total organic content of sediments beneath. However, increased values of Vibrio spp. in bio deposits within the pilot farm (1.43 106 ± 1.10 106CFU 100 ml−1 (reference site: 1.04 106 ± 1.45 106 CFU 100 ml−1) were measured with sediment traps. Hence, mussel farms might act as a sink for Vibrio spp. in systems with already high vibrio concentrations. However, more research is required to investigate the risks of Vibrio occurrence coupled to mussel farming. The economic model showed that mussel cultivation in environments below 12 PSU cannot be economic at current market prices for small size mussels and compensations based on nutrient removal cost of WWTPs.

COST ANALYSIS OF BENEFITS AND ECOLOGICAL SOCIAL SYSTEM GREEN SHELL CULTIVATION IN SERANG CITY

Mussels are included as part of aquaculture leading commodities in Banten Province. Green mussel is one of the mussels that has been cultivated in Banten, especially in Serang City. The purposes of this research are to analyze feasibility comparison based on differences in cultivation methods, analyze connectivity of social ecological systems (SES) in green mussel cultivation, and formulate solutions to develop a good and sustainable green mussel cultivation in Serang City. The analytical methods are analysis of cost-benefit, and descriptive based on the link in the SES. The results show that stake method is more feasible based on cost-benefit analysis indicators. The problems found based on connectivity in SES subsystems of green mussel cultivation in Serang City are there is sediment that can obstruct green mussel growth on the site, disposing of garbage in the sea, conflicts between cultivators and fishermen, the coaching without further monitoring yet, no waste processing technology, and no accomodation from the city government related to cultivation components. The Recommendations that can be given are the need to dredge and study the condition of sea location, giving education about the condition of sea environmemt, doing arrangement of sea zonation rules, monitoring the implementation of coaching results, giving accomodation with guidance related to the processing of production waste, and subsidies cultivation components by the city government.Key words: analysis of cost-benefit, green mussel, marineculture, social ecological system, policy

Study on the Suitability of Green Mussel (Perna viridis) Culture in North Sea Waters of Java, Ketapang Village, Tangerang District, Banten Province

Green mussel is one of the fisheries resources have to be developed to prospective higheconomically valuable commodities .This is proportional to the nutrition beef , eggs and chicken .This indicates that green shell are mostly potential can be developed through the cultivation .The study is done at july until august sea north of java in 2019 , the village Ketapang , Mauk district , Tangerang , Banten .The data under the four station representing village ketapang waters .The methodology used by approaching purposive sampling method uses the data analysis by the ratings point .The village ketapang skoring waters that is both life and research sites support green shell that could be used as the green mussel cultivation .

BIOCONCENTRATION OF CADMIUM HEAVY METAL (CD) ON GREEN MUSSLE Perna Viridis Linn, 1758 CULTIVATED IN PASARAN ISLAND WATERS, LAMPUNG, INDONESIA

Pasaran Island waters is the location of green mussel cultivation (Perna viridis), where the waters has the potential to experience heavy metal pollution including Cadmium (Cd). Green mussels are filter feeders and have a slow movement, thus they have the potential to experience heavy metal bioconcentration on their bodies. The aim of this study was to determine the bioconcentration of heavy metal cadmium (Cd) in green mussels (Perna viridis) which were cultivated in the waters of Pasaran Island. Samples were collected in February 2018 in green mussel cultivating cages of Pasaran Island water with 3 and 6 cm mussel size. Sampling was taken at three stations with three replications each. The Cd content was analyzed using AAS method. The results showed that the water content of Cd at the observation location ranged from 0.022 to 0.024 mg/l. The content of Cd of mussel meat is 0.030 to 0.033 mg/kg, the value is below the threshold based on Indonesian National Standard (SNI). The BFC value of 3 cm mussel is 1.33 mg/kg, while the 6 cm mussel is 1.47 mg/kg which indicates that the green mussels on Pasaran Island are accumulatively low on Cd.