The present study was carried out on the quantification of heavy metals cadmium, lead, copper, chromium, nickel and zinc in the bivalve mollusk concha prieta (Anadara tuberculosa) using the technique of inductively coupled plasma optical emission spectroscopy ICP-OES. The research aims to identify whether the bioaccumulated content of heavy metals exceeds the maximum limits established by various public health bodies such as the ONU, FAO, Codex Alimentarius, EEC and NHI. Samples of the species were collected randomly from three locations in Puerto El Morro, Playas Municipal Market and La Libertad Seafood Market in the Gulf of Guayaquil. Thirty-three soft tissue samples of Anadara tuberculosa were evaluated, the values quantified in mg/kg follow the following order in relation to the mean Zn>Cu>Cd>Ni>Cr>Pb.

The life cycles and biodiversity of Pacific coast gastropods were analyzed by videomicroscopy and DNA barcoding of indi-viduals collected from tide pools and in plankton nets from a variety of shore stations. In many species (Families Calyptrae-idae, Cerithiopsidae, Strombidae, Vermetidae, Columbellidae, Nassariidae, Olivellidae, Hermaeidae, Onchidorididae, Gas-tropteridae, Haminoeidae), the free-swimming veligers were recovered from plankton collections; in Roperia poulsoni (family Muricidae) veligers were usually recovered from egg sacs where they had been retained although some escapees were found in plankton collections; in Pteropurpura festiva (family Muricidae) free-living veligers were also found; and in Atlanta californiensis (family Atlantidae) both veligers and adults were obtained from plankton collections making this a holoplank-tonic species. The results confirm that DNA barcoding using the COI barcode is a useful strategy to match life-cycle stages within species as well as to identify species and to document the level of biodiversity within the gastropods.

The increase in hypoxia events, a result of climate change in coastal and fjord ecosystems, impacts the health and survival of mussels. These organisms deploy physiological and molecular responses as an adaptive mechanism to maintain cellular homeostasis under environmental stress. However, the specific effects of hypoxia on mussels of socioeconomic interest, such as Mytilus chilensis, are unknown. Using RNA-seq, we investigated the transcriptomic profiles of the gills, digestive gland, and adductor muscle of M. chilensis under hypoxia (10 days at 2 mg L-1) and reoxygenation (10 days at 6 mg L-1). There were 15,056 differentially expressed transcripts identified in gills, 11,864 in the digestive gland, and 9,862 in the adductor muscle. The response varied among tissues, showing chromosomal changes in Chr1, Chr9, and Chr10 during hypoxia. Hypoxia regulated signaling genes in the Toll-Like, mTOR, citrate cycle, and apoptosis pathways in gills, indicating metabolic and immunological alterations. These changes suggest that hypoxia-induced a metabolic shift in mussels, reducing reliance on aerobic respiration and increasing reliance on anaerobic metabolism. Furthermore, hypoxia appeared to suppress the immune response, potentially increasing disease susceptibility, with negative implications for the mussel culture industry and natural bed populations. This study provides pivotal insights into metabolic and immunological adaptations to hypoxia in M. chilensis, offering candidate genes for adaptive traits.

The bivalve mollusk, Anadara tuberculosa (Black Shell, in Spanish Concha prieta, "CP"), is found on America's Pacific coast, where it is harvested for subsistence and commercial markets. This paper aims to diagnose the performance of the black shell's value chain. We also identify several challenges that must be addressed to improve the sustainability of the black shell fishery in Ecuador. The descriptive methodology was quantitative, with a non-experimental, field, cross-sectional, and ex post facto design. Similar questionnaires were designed, validated, and applied to each link in the production chain to collect information. The performance of the value chain was diagnosed in the dimensions of productivity, competitiveness, and quality of life, reaching a 75.1% index, a result that indicates that the value chain has a moderate to good performance level. However, the value chain can be improved if the following challenges are met: 1) Restoration of the mangrove ecosystem, 2) Promotion of low-intensity shellfish aquaculture, 3) Good sanitary management and purification, 4) Promotion of value-focused ventures, 5) Strengthening of organizations and agreements for the use and custody of mangroves, and 6) Strengthening of institutions that contribute to the advancement of these challenges.