Search

Microplastics (MPs) are prevalent in aquatic environments worldwide, but the occurrence of MPs in different mariculture modes has not been clarified. Four extensively cultured bivalves and ambient surface water were collected to study the MPs pollution characteristics of different mariculture modes. The results indicated that MPs abundance in the inland mode water was 2.5 times higher than that in the marine mode water. The MPs hazard index was evaluated as 655, 390, and 23 in the surface water of the inland, coastal, and marine aquaculture modes, respectively. The MPs abundance in the bivalves in the inland mode was significantly higher than that in the other two modes. There was a positive relationship between the MPs characteristics in the mariculture water and in the cultured bivalves. The abundance of MPs in the four bivalves (calculated items/g) was negatively correlated with soft tissue weight. This study further improves the understanding of MPs pollution characteristics in different aquaculture modes and further highlights the general transmission risk of MPs in various aquaculture systems. [Display omitted] • The MPs abundance in the inland mode water was 2.5 times higher than that in the marine mode water. • The MPs hazard index was evaluated in the surface water of various aquaculture systems. • Of the mariculture modes, the inland mode had the highest MPs abundance. • MPs characteristics in the water and bivalves were consistent. [ABSTRACT FROM AUTHOR]

We investigated the effects of culture mode (intertidal and off-bottom suspended culture) and initial stocking density (5%, 10%, 35% and 70% bottom cover) on survival, growth and condition indices of three size cohorts (16, 22 and 32 mm initial shell length) of the basket cockle, Clinocardium nuttallii, during a second year of grow-out. In addition, we evaluated the effects of depth (2, 4 and 6 m) in suspended culture. All size cohorts demonstrated significantly higher growth rates, soft-tissue biomass and condition indices in the off-bottom suspended system compared to the intertidal one. In suspended culture, however, C. nuttallii exhibited sub-optimal survival, shell deformities and heavy fouling. For all size cohorts, stocking density had a significant effect on most growth and condition parameters, except meat yield indices, in both culture modes. An initial maximum stocking density of 10% cover is recommended for all size cohorts. Culture depth did not have a consistent statistically significant effect on any of the growth or condition parameters. Depending on the grow-out scenario, stocking density and harvestable size chosen, the cumulative harvestable proportion after the second year of grow-out constituted 15.5-63.1% of the seed planted. Our results could be used to develop and improve culture techniques for C. nuttallii and other cockle species. [ABSTRACT FROM AUTHOR]

The basket cockle ( Clinocardium nuttallii) is a candidate species for aquaculture in the northeast Pacific. The aim of the current research was to assess the feasibility of C. nuttallii grow-out, with an emphasis on growth performance and qualities affecting product marketability. In this article, we investigated the combined effects of culture mode (intertidal and off-bottom suspended culture) and initial stocking density (1500, 3000, 10 500 and 21 000 ind m−2) on C. nuttallii survival and growth during the first year of grow-out ( May through October). In intertidal culture, cockles exhibited low survival and poor growth rates. In suspended culture, survival was consistently high (>96%) at all stocking densities tested; growth and condition parameters had the highest values at 1500 and 3000 ind m−2. The edible portion (meat yield) exceeded 40% of the whole wet weight at all stocking densities, occurrences of fouled and deformed cockles were <1% and no commensal species were observed. Depending on the minimum harvestable size and stocking density chosen, harvestable proportions constituted from 1.1% to 15.2% by October of the first grow-out year in the suspended system. The effects of stocking density and depth on second year grow-out performance of C. nuttallii are reported in a companion paper (Dunham et al. in this issue). [ABSTRACT FROM AUTHOR]