Search

Mass oyster mortality occurred at an oyster farm in the Setiu Lagoon on the east coast of Peninsular Malaysia in December 2023. According to interviews with aquaculture farmers, heavy rains that occurred from 20 November to early December caused flooding in the surrounding area, leaving it exposed to low-salinity water for a long period. Mass mortality occurred at oyster farms in early December, with farmers estimating that the dead oysters had a shell length of 1–5 cm and mortality rate of over 90%, and that approximately 50,000 oysters had died. An analysis of meteorological data indicated that a monthly rainfall value of more than 1200 mm/month, which is more than double the normal amount, was observed in November in the same region. During the same period, the seawater temperature in the South China Sea was 1°C higher than normal, and the northeast monsoon caused winds from the northeast to transport moist air to the eastern coast of Peninsular Malaysia, causing heavy rain. Currently, only one waterway, approximately 200 m wide, connects the lagoon to the sea. Until approximately 2012, two waterways were connected to the sea. We concluded that by increasing the number of channels to two, the decrease in salinity in the lagoon during the rainy season could be reduced by enhancing phytoplankton occurrence.

Ulva green tides have adversely affected coastal ecosystems. In June 2023 in Changhua County, Taiwan, an unprecedented floating tubular Ulva bloom spanning about 30 km of coastline caused about 30 % reduction in oyster yield as reported by local farmers. Understanding its taxonomic and ecological basis is crucial for preemptive and remedial measures. Based on molecular (rbcL and tufA) and morphological evidence, Ulva meridionalis was the cause of this green tide. Haplotype network analysis (based on ITS) suggests that this green tide originated from northern China via the China Coastal Current. Historical survey data indicate that U. meridionalis arrived in Taoyuan Algal Reef (about 150 km north of the bloom area) as far back as 2018. Our ecophysiological experiments revealed that U. meridionalis exhibited a rapid daily growth rate with biomass increment up to 13–21 % when subjected to local nutrient-rich waters under lower salinity and spring-like conditions. Although historical ecological and poultry/livestock data analyses showed no noticeable change in sea surface temperature and rainfall over the past decade, a gradual rise in agricultural nitrogen and phosphorus output was observed. This taxonomic and ecological background lays the groundwork for long-term ecological monitoring. Moreover, this study exemplifies the detrimental impact of an unforeseen Ulva bloom on oyster farming. [ABSTRACT FROM AUTHOR]

Ostrea chilensis (a flat oyster) is native to Chile and New Zealand. In Chile, this oyster has been cultured and harvested for at least 80 years. However, the culture of flat oysters has not developed like other aquaculture activities in Chile, mainly due to the inefficiency of the collectors (made of ribbed mussel shells) and the lack of spats produced. The objective of this study was to determine the capacity of spat collectors for the settlement of O. chilensis. For this purpose, field and laboratory experiments were carried out. Our results indicated that oyster larvae do not have a preference for either side of the shell (periostracum or nacreous) to settle on. However, after one year of growth in the field, juveniles were more abundant on the nacreous side of the shell (spat collector). Also, the oysters that settled on the nacreous side of the valve were larger. This was due to the fact that the periostracum had a greater number of epibionts, and they competed for space and resources with the settled oyster spats, causing a decrease in the abundance of oyster spats on that surface. Our findings raise the possibility that collectors could improve efficiency in the production of spats. Finally, we discuss the implications of these results for the Chilean oyster-farming industry. [ABSTRACT FROM AUTHOR]

Nonlinear regression modeling was used to study the nursery production of the oyster Crassostrea virginica in the Celestún (CL) and Rio Lagartos (RL) lagoons in Yucatán, Mexico. Relationships between production parameters and environmental variables were also established. Spat (2.40 ± 0.20 mm) was obtained from a hatchery and reared in Nestier- type trays using an off-bottom system. Oyster cultivation took place from May 2021 to September 2021 and ended after 122--126 days when oysters reached 30.00 mm. There were no significant differences in final height (CL: 30.80 ± 0.42 mm; RL: 31.80 ± 0.65 mm; P = 0.18) and growth rate (CL: 0.23 ± 0.02 mm·d-1; RL: 0.23 ± 0.01 mm·d-1; P = 0.98). Final survival was 71.45% in CL and 99.40% in RL. Nonlinear regression curves were statistically satisfactory for analyzing growth and survival. Salinity (CL: 15.23 ppt; RL: 35.02 ppt), temperature (CL: 29.64 °C; RL: 31.02 °C), dissolved oxygen (CL: 4.50 mg· L-1; RL: 5.04 mg· L-1), pH (CL: 8.10; RL: 8.34), chlorophyll a (Chl a) (CL: 3.23 mg·m--3; RL: 6.85 mg·m--3), and total dissolved solids (CL: 16,101 mg·L-1; RL: 34,838 mg·L-1) were significantly higher in RL (P < 0.05). Except for Chl a, the environmental variables were more stable in RL than in CL (P < 0.05). In RL, the growth rate was positively related to salinity and pH. In CL, the growth rate slowed when salinity decreased, and the mortality rate diminished when salinity, dissolved oxygen, and total dissolved solids increased and pH decreased. Salinity was mainly responsible for the observed differences in production between lagoons. Even when temperature and salinity were high in RL, acceptable growth rate and survival were observed, possibly due to stable rearing conditions. [ABSTRACT FROM AUTHOR]

Abstract In this study, we aimed to evaluate the synergistic effect between the Amazon seasonality and the El Niño climate anomaly (2015/16 event) on the growth of oysters cultivated on the Amazon coast in comparison with the growth of oysters in a normal year (2013). It should be noted that both experiments determined the absolute growth of oysters Crassostrea gasar by reading microgrowth using an internal calcein marker. the results clearly indicate the synergistic effect of the Amazon seasonality with the El Niño climatic anomaly. thus, in normal years, the best oyster growth performance occurs in the dry season, while in El Niño years it occurs in the wet season. This is the first study carried out in the Amazon region that aims to analyze the effects of El Niño on the production of fishery resources from aquaculture. Such information enables adaptations in the planning of the production cycle of oyster farming, serving as an investment indicator.

Plastic materials are widely used for automotive parts, electronic devices, and faucet parts because they are lighter than metals and have superior workability and productivity. However, due to their poor weather resistance, their surfaces must be painted or plated. As a pretreatment for plating, it is most important to roughen the surface to obtain strong adhesion through an anchor effect. The conventional method is to use chemicals, but the use of chemicals is now severely restricted by the REACH regulation in the EU due to the environmental impact of wastewater and effluent treatment. We have obtained the same or higher adhesion strength than conventional methods by using a pretreatment method with ozone fine bubbles, which has almost no environmental damages. [ABSTRACT FROM AUTHOR]

Ostrea chilensis (a flat oyster) is native to Chile and New Zealand. In Chile, this oyster has been cultured and harvested for at least 80 years. However, the culture of flat oysters has not developed like other aquaculture activities in Chile, mainly due to the inefficiency of the collectors (made of ribbed mussel shells) and the lack of spats produced. The objective of this study was to determine the capacity of spat collectors for the settlement of O. chilensis. For this purpose, field and laboratory experiments were carried out. Our results indicated that oyster larvae do not have a preference for either side of the shell (periostracum or nacreous) to settle on. However, after one year of growth in the field, juveniles were more abundant on the nacreous side of the shell (spat collector). Also, the oysters that settled on the nacreous side of the valve were larger. This was due to the fact that the periostracum had a greater number of epibionts, and they competed for space and resources with the settled oyster spats, causing a decrease in the abundance of oyster spats on that surface. Our findings raise the possibility that collectors could improve efficiency in the production of spats. Finally, we discuss the implications of these results for the Chilean oyster-farming industry.

Non-indigenous seaweed species have been introduced to the coasts of Brittany, France for decades, with an increasing arrival rate since the 1970s due to both the introduction of the Pacific oyster and increased maritime traffic. In this study, seven species of red macroalgae originating from the Pacific Ocean were found in new locations around the coasts of Brittany between 2018 and 2022. The seaweed species belong to four different orders: Ceramiales (Antithamnion hubbsii, Polysiphonia morrowii, and Symphyocladiella dendroidea), Halymeniales (including Pachymeniopsis lanceolata and Polyopes lancifolius), Rhodymeniales (Botryocladia wrightii), and Gigartinales (Solieria sp.). The dispersal mode and putative invasive potential of each species were examined, and the species were described in terms of their macroscopic and microscopic appearance and habitat. These finds result from a combination of citizen science and long-term monitoring. Used together, these two approaches can aid in the detection of these species on other European coasts and in understanding their dispersion. [ABSTRACT FROM AUTHOR]

The Pacific oyster Crassostrea gigas is one of the world's most cultivated and prized molluscs. Although it is usually considered a luxury product, it meets all the requirements to be included in a sustainable diet, and its production and consumption have great potential for growth in the coming years. Oyster farming is a worldwide activity, with China and France as the main producers, but recently, the possibility of implementing the Italian production, mainly focused on clams and mussels, has been considered an interesting issue, especially due to the growing local and global demand. The present study has been carried out by collecting data from the Sacca di Goro, north-east Italy, the most important national mollusc farming area. Life cycle assessment (LCA) methodology was applied to two different farming scenarios in order to improve the overall sustainability of the process. Using OpenLCA™ software (GreenDelta, Berlin, Germany) and the ReCiPe® midpoint (H) v.1.12 method, the environmental impacts of the traditional Italian farming technique, carried out entirely offshore in longlines, and the alternative option, in which the oyster seed pre-fattening phase was carried out in the lagoon, were calculated and compared. The results show that replacing the current pre-fattening phase with pre-fattening in a lagoon reduces CO2 emissions by approximately 12% and all other impact categories by approximately 9%. In addition, non-recyclable plastic materials and fuel consumption emerged as the main environmental hotspots. [ABSTRACT FROM AUTHOR]

Although Crassostrea nippona and C. gigas are occasionally found to be sympatric, little is known about the differences in tolerance against environmental stresses between species, which may potentially result in severe economic losses due to the neglect of species-specific biological characteristics in farming practices. Therefore, two independent and consecutive experiments were performed to evaluate the differences in temperature and salinity tolerance between C. nippona and C. gigas spat and determine the optimal environmental conditions for the aquaculture of C. nippona spat. The experimental results of dynamic treatment showed that the accumulative survival rate (ASR) of C. nippona spat was generally lower than that of C. gigas throughout temperature changes and salinity decreases, while the ASR of C. nippona spat was superior to that of C. gigas with increasing salinity. In addition, the daily growth rate (DGR) of both species was significantly inhibited at 18 °C and peaked at 25 °C with increasing temperature (p < 0.05) at each experimental salinity. At 32 °C, the survival rate (SR) of C. nippona spat was significantly lower than that of C. gigas on day 10 at all salinities tested (p < 0.05), whereas the difference in the SR between species at 35 psu gradually disappeared with prolonged stress time. The data indicated that C. gigas spat was suitable for rearing at temperatures of 25 and 32 °C at all salinity levels, except the combination of 32 °C and 35 psu. By contrast, combinations of 25 °C and salinities of 21–35 psu were considered as the optimal environmental conditions for the long-term culture of C. nippona spat. These present findings contribute to a better understanding of the tolerance of C. nippona spat to environmental stresses and suggest that particular attention should be paid to the inferior adaptability of C. nippona when farming in locations outside their natural habitats. [ABSTRACT FROM AUTHOR]

Coastal erosion in the lagoon systems is concerned as they are dynamic landscapes, often highly productive and beneficial to humankind. Cigu Lagoon contains rich and diverse ecosystems ranging from mangroves to salt fields, and from fish to birds (e.g., endangered black-faced spoonbill). As well as forming part of the country’s natural defenses against typhoons and storm surges, it is also economically important for oyster farming, fish-pond aquaculture and ecotourism. However, with the construction of reservoir, fishery harbors and breakwaters, sediment transport decreases and sand barrier islands have eroded, narrowed, lowered and moved landwards. Cigu is a rural area with decreasing, aging population, becoming a “super-aged society” as defined by World Health Organization. Therefore, it is imperative to study the socioeconomic impacts of these changes, and then to explore critical adaptation factors and potential adaptation strategies. In this research, we conducted interviews and a fuzzy analytic hierarchy process survey. Diverse stakeholders were identified and mapped using a stakeholder rainbow diagram and a power–interest grid. The results show that stakeholders consider the economy to be the most important adaptation factor, especially in relation to the employment opportunities. There are some forms of livelihood diversification in Cigu. Collaboration among young entrepreneurs is the key to socioeconomic adaptation. These factors and strategies may foster socioeconomic adaptation to coastal erosion or geomorphological change, to be aggravated by climate change and other stressors.

Oysters are one of the main aquatic products produced in Taiwan. However, because of the gradual changes in the environment of the Waisanding Sandbar, the oyster farming environment along the coast of Chiayi is shrinking, leading to greater operational risk and uncertainty. This study adopted a three-stage method to investigate the socioeconomic uncertainty that fishing communities face regarding environmental changes and to understand the environmental risk and fishery management awareness of different stakeholders as well as their views on adaptation strategies. In-depth interviews were used in the first stage. In Stage 2, two-round focus group interviews were conducted to organize views on the environment and climate, the oyster industry and management, and adaptation strategies. In the final stage, the AHP method was adopted to analyze the opinions of different stakeholders. The results showed factors affecting environmental change, oyster industry, and management among different stakeholders as well as the cognitive differences within the corresponding adaptation strategies. Therefore, socioeconomic and ecology complexities and uncertainties should be considered for enhancing social capital and promoting risk communication, more diverse social–ecological system data to assist fishery governance, and oyster industry development and adaptation strategies. [ABSTRACT FROM AUTHOR]

Abstract Due to the competition for food, space, oxygen and due to their role as diseases vector, epibionts can negatively affect oyster farming. We assessed the efficacy of six methods commonly used for the removal of epibionts from oyster shells during farming. The experiment was conducted at an oyster farm on the Paraná coast – South Brazil. Oysters (Crassostrea gasar) were acclimated for 90 d in the cultivation system and later exposed to cleaning treatments: i) freshwater; ii) hypersaline water; iii) sodium hypochlorite solution; iv) quaternary ammonia solution; v) exposure to air; vi) hydroblasting; and vii) no cleaning procedure (control). After treatment, oysters were kept in the cultivation system for 15 and 30 d – when the total incrustation and mortality were measured. Epibionts from nine phyla were identified. The most abundant were Arthropoda (Crustacea) (62.5%), Mollusca (33.8%) and Annelida (3.1%). Freshwater [15 (n = 2263 epibionts) and 30 days (n = 2822 epibionts)] and hydroblasting [15 (n = 1850 epibionts) and 30 days (n = 2389 epibionts)] treatments were the most efficient to reduce epibionts and caused lower rates of oyster mortality [15 (5.0 and 3.33%, respectively) and 30 days (1.67 and 6.67%, respectively)].

The Pacific oyster Crassostrea gigas is one of the world’s most cultivated and prized molluscs. Although it is usually considered a luxury product, it meets all the requirements to be included in a sustainable diet, and its production and consumption have great potential for growth in the coming years. Oyster farming is a worldwide activity, with China and France as the main producers, but recently, the possibility of implementing the Italian production, mainly focused on clams and mussels, has been considered an interesting issue, especially due to the growing local and global demand. The present study has been carried out by collecting data from the Sacca di Goro, north-east Italy, the most important national mollusc farming area. Life cycle assessment (LCA) methodology was applied to two different farming scenarios in order to improve the overall sustainability of the process. Using OpenLCA™ software (GreenDelta, Berlin, Germany) and the ReCiPe® midpoint (H) v.1.12 method, the environmental impacts of the traditional Italian farming technique, carried out entirely offshore in longlines, and the alternative option, in which the oyster seed pre-fattening phase was carried out in the lagoon, were calculated and compared. The results show that replacing the current pre-fattening phase with pre-fattening in a lagoon reduces CO2 emissions by approximately 12% and all other impact categories by approximately 9%. In addition, non-recyclable plastic materials and fuel consumption emerged as the main environmental hotspots.

Ocean space is of paramount importance to coastal regions worldwide. However, rapid coastal development has led to competition in marine spatial allocation, exacerbating conflicts within maritime domains. Despite significant progress in establishing regulations for coastal governance in Taiwan, conflicts across diverse maritime industries due to a lack of marine spatial planning (MSP) institutions remain a persistent challenge. Potential conflict areas were identified via geographic information system (GIS) maps to assist maritime governance and used in several rounds of coordination meetings with stakeholders for zoning. A regional MSP framework for improving maritime governance is proposed based on a case study, which shows that even without legal MSP institutions, local or certain central government departments can act as the key authorities for implementing the bottom-up planning concept with strong engagement from local communities. The proposed planning process includes: (1) establishing and employing a monitoring system to promptly identify marine activities that can facilitate efficient enforcement; (2) continuous communication with stakeholders led by the local government to improve amendment regulations and aid compliance; and (3) prioritizing the preservation of traditional use rights with community self-management to accelerate regional MSP processes. • GIS maps assist in identifying conflict-prone areas, aiding stakeholder coordination. • Lacking legal MSP frameworks, local governments facilitate bottom-up planning, engaging communities in maritime governance. • Implementing a monitoring system enhances enforcement efficiency by swiftly identifying various marine activities. • Prioritizing traditional use rights and involving communities in self-management expedites the regional MSP process. [ABSTRACT FROM AUTHOR]

The Santa Catarina Island Bay (SCIB) contributes with the largest production of cultivated oysters in Brazil, which is almost entirely based on hatchery produced cultchless oyster spat, whose metamorphosis is induced by an epinephrine solution. A production scale experiment was carried out to analyze the technical feasibility of the spat-on-shell system in SCIB. The experiment was carried out for 47 weeks, involving an internal phase, the larval settlement, and an external phase, encompassing nursery and growth. Nursery periods varied according to the experimental treatments: T3W - 3 weeks; T5W - 5 weeks; and T12W - 12 weeks. T3W and T5W showed lower survival during the two-week period shortly after transfer of the cultch from the nursery to the grow-out phase, likely linked to premature exposure of the spat in the cultch strings to predators such as fish. The 12-week nursery period showed the best results with clusters with a median of 6 animals and 11.4 g of meat per oyster at the end of the experimental period. Future studies could verify whether longer nursery periods or alternative methods to avoid exposure to predators can outperform these results.

The Pacific oyster (Crassostrea gigas) is an important species in oyster farming worldwide, including in Japan. Hiroshima Bay is one of the most important oyster farming areas in Japan. We investigated the occurrence of antifouling biocides used worldwide including diuron, Irgarol 1051 (Irgarol), and 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT), which have been detected at sub-ppb levels in seawater in Japan, and estimated their no observed effect concentrations (NOECs). In recent years, the spat settlement of Pacific oysters has become poor, which presents a challenge for oyster aquaculture in Hiroshima Bay; hence, we conducted embryotoxicity and larva settlement tests using Pacific oysters. Compared to diuron and Irgarol, DCOIT exhibited a higher toxicity toward oyster embryos, and the minimum 24-h NOEC toxicity value for the oyster embryos was <3 ng/L. The highest concentrations of diuron, Irgarol, and DCOIT in the environmental seawater in the Seto Inland Sea were 27.6, 3.2, and 24 ng/L, respectively. Considering the NOECs, the environmental concentrations of these biocides suggest that the ecological risks posed by diuron and Irgarol are low, whereas those posed by DCOIT are high. However, the rate of detection of DCOIT was low because it degraded rapidly in the seawater before treatment for chemical analysis, except in the case of the treatment on the research vessel. [ABSTRACT FROM AUTHOR]

The Santa Catarina Island Bay (SCIB) contributes with the largest production of cultivated oysters in Brazil, which is almost entirely based on hatchery produced cultchless oyster spat, whose metamorphosis is induced by an epinephrine solution. A production scale experiment was carried out to analyze the technical feasibility of the spat-on-shell system in SCIB. The experiment was carried out for 47 weeks, involving an internal phase, the larval settlement, and an external phase, encompassing nursery and growth. Nursery periods varied according to the experimental treatments: T3W - 3 weeks; T5W - 5 weeks; and T12W - 12 weeks. T3W and T5W showed lower survival during the two-week period shortly after transfer of the cultch from the nursery to the grow-out phase, likely linked to premature exposure of the spat in the cultch strings to predators such as fish. The 12-week nursery period showed the best results with clusters with a median of 6 animals and 11.4 g of meat per oyster at the end of the experimental period. Future studies could verify whether longer nursery periods or alternative methods to avoid exposure to predators can outperform these results. [ABSTRACT FROM AUTHOR]

Although Crassostrea nippona and C. gigas are occasionally found to be sympatric, little is known about the differences in tolerance against environmental stresses between species, which may potentially result in severe economic losses due to the neglect of species-specific biological characteristics in farming practices. Therefore, two independent and consecutive experiments were performed to evaluate the differences in temperature and salinity tolerance between C. nippona and C. gigas spat and determine the optimal environmental conditions for the aquaculture of C. nippona spat. The experimental results of dynamic treatment showed that the accumulative survival rate (ASR) of C. nippona spat was generally lower than that of C. gigas throughout temperature changes and salinity decreases, while the ASR of C. nippona spat was superior to that of C. gigas with increasing salinity. In addition, the daily growth rate (DGR) of both species was significantly inhibited at 18 °C and peaked at 25 °C with increasing temperature (p < 0.05) at each experimental salinity. At 32 °C, the survival rate (SR) of C. nippona spat was significantly lower than that of C. gigas on day 10 at all salinities tested (p < 0.05), whereas the difference in the SR between species at 35 psu gradually disappeared with prolonged stress time. The data indicated that C. gigas spat was suitable for rearing at temperatures of 25 and 32 °C at all salinity levels, except the combination of 32 °C and 35 psu. By contrast, combinations of 25 °C and salinities of 21–35 psu were considered as the optimal environmental conditions for the long-term culture of C. nippona spat. These present findings contribute to a better understanding of the tolerance of C. nippona spat to environmental stresses and suggest that particular attention should be paid to the inferior adaptability of C. nippona when farming in locations outside their natural habitats.

Norovirus is a significant global cause of viral gastroenteritis, with raw oyster consumption often linked to such outbreaks due to their filter-feeding in harvest waters. National water quality and depuration/relaying times are often classified using Escherichia coli , a poor proxy for norovirus levels in shellfish. The current norovirus assay is limited to only the digestive tracts of oysters, meaning the total norovirus load of an oyster may differ from reported results. These limitations motivated this work, building upon previous modelling by the authors, and considers the sequestration of norovirus into observed and cryptic (unobservable) compartments within each oyster. Results show that total norovirus levels in shellfish batches exhibit distinct peaks during the early depuration stages, with each peak's magnitude dependent on the proportion of cryptic norovirus. These results are supported by depuration trial data and other studies, where viral levels often exhibit multiphase decays. This work's significant result is that any future norovirus legislation needs to consider not only the harvest site's water classification but also the total viral load present in oysters entering the market. We show that 62 h of depuration should be undertaken before any norovirus testing is conducted on oyster samples, being the time required for cryptic viral loads to have transited into the digestive tracts where they can be detected by current assay, or have exited the oyster. • Several studies report multiphase decay of norovirus in oysters during depuration. • The model splits norovirus loads into cryptic (unobservable) and observable compartments within oysters. • Results synthesise reported multiphase decay of norovirus, with levels of cryptic norovirus dissipating after ≈ 62 hours of depuration. • To minimise food safety risks to consumers, any future legislation should assay oyster norovirus levels after 62 h of depuration to account for any cryptic norovirus levels present. [ABSTRACT FROM AUTHOR]

Purpose - To determine the sociocultural characteristics and unravel the ethnomathematics in Panaeaba or oyster farming of the fourteen Manugtaeaba (oyster farmer) purposively chosen as informants and paired the mathematical concepts and principles found in Panaeaba to K12 Mathematics. Method - This focused ethnographic study was generally governed by the epistemological umbrella of constructionism and symbolic interactionism as its interpretive approach for the thematic, ethnomathematical and document analyses. Data gathered through ethnographic interview and observation and collection of artifacts. Findings - Ethnomathematics along Numbers and Number Sense, Algebra, Measurement, and Geometry were used in Panaeaba. The Ethnomathematical Knowledge, Practices and Skills (EKPS) on numbers and number sense used by Manugtaeaba were rational numbers, counting, equality and inequality, estimation, fundamental, ratio and proportion. For EKPS along algebra includes the parabola, relations, and functions in line with size or area of oyster shell, density of spat collection, buoyancy, and navigational speed. Also, the EKPS along measurement includes how farmers used standard and alternative measurement on area, volume, distance, height, length, and time in oyster farming. The EKPS along geometry includes angles, and parallelism. These EKPS are influenced by the sociocultural characteristics in terms of Manugtaeaba's beliefs and attitude towards family and work. Significance - From the unraveled EKPS in Panaeaba, the researcher came up with the matrix of the mathematical concepts and principles and K-12 learning competencies known as TALAMATH. From this TALAMATH (Teaching A Localized and Actualized Mathematics), lesson exemplars that can be used in the teaching of mathematics and will serve as guide for the development of instructional materials contextualized in oyster farming were made. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Splendidus clade is predominant in oysters from central Chile. • Virulence is present in non-intensive farming environments. • Hemolytic activity was positive for 50% of the virulent strains. • Enzymes related to virulence are produced by the isolated vibrios. Farming intensification and climate change are inevitably linked to pathogen emergence in aquaculture. In this context, infectious diseases associated with vibrios span all developmental stages of the Pacific Oyster Crassostrea gigas. Moreover, virulence factors associated with pathogenicity spread among the vibrio community through horizontal gene transfer as part of the natural eco-evolutive dynamic of this group. Therefore, risk factors associated with the emergence of pathogens should be assessed before the appearance of mass mortalities in developing rearing areas. In this context, we characterized the vibrios community associated with oysters cultured in a non-intensive area free of massive mortalities located at Tongoy bay, Chile, through a culture-dependent approach. We taxonomically affiliated our isolates at the species level through the partial sequencing of the heat shock protein 60 gene and estimated their virulence potential through experimental infection of juvenile C. gigas. The vibrio community belonged almost entirely to the Splendidus clade, with Vibrio lentus being the most abundant species. The virulence potential of selected isolates was highly contrasted with oyster survival ranging between 100 and 30 %. Moreover, different vibrio species affected oyster survival at different rates, for instance V. splendidus TO2_12 produced most mortalities just 24 h after injection, while the V. lentus the most virulent strain TO6_11 produced sustained mortalities reaching 30 % of survival at day 4 after injection. Production of enzymes associated with pathogenicity was detected and hemolytic activity was positive for 50 % of the virulent strains and negative for 90 % of non-virulent strains, representing the phenotype that better relates to the virulence status of strains. Overall, results highlight that virulence is a trait present in the absence of disease expression, and therefore the monitoring of potentially pathogenic groups such as vibrios is essential to anticipate and manage oyster disease emergence in both established and under-development rearing areas. [ABSTRACT FROM AUTHOR]

In the past few decades, with the rapid economic development of China and Vietnam, the marine ecological environment of Beibu Gulf is facing increasing pressure. To understand the impact of anthropogenic inputs on marine ecology, high-performance liquid chromatography (HPLC) was used to study phytoplankton in this paper. We examined the influence of anthropogenic inputs on phytoplankton biomass and community structure in a subtropical estuary. Anthropogenic inputs had significantly increased the nutrient concentration in the estuary between 2010 and 2015. We observed that phosphorus limitation has been greatly relieved in 2015. However, the biomass of dominant phytoplankton was lower in 2015 than in 2010, possibly due to the expansion of oyster farming in the estuary. The coverage of oyster rafts was estimated to be 26.3 km2. The presence of dense oysters may significantly reduce the phytoplankton biomass. The proportion of Diatoms decreased while some nano- and pico-phytoplankton (like Cryptophytes and Prasinophytes) increased, which indicated that oysters changed not only the biomass but also the size of phytoplankton communities. This study improved our understanding of anthropogenic inputs on phytoplankton communities in subtropical estuary. [ABSTRACT FROM AUTHOR]

Oyster farming has been threatened by marine flatworms for over 40 years, but few studies have been done to address this issue. Here, we examine the predatory behavior of the polyclad flatworm Cryptostylochus sp. from Penghu, Taiwan. Its predation process consists of three parts: the attack, invasion, and ingestion period. During the attack period, which begins 4 or more hours before the invasion, protruding pharynges form fragments that we call "autonomic pharynges". The autonomic pharynx is translucent white, membrane-like, and variable in length. Using time-lapse photography, we show that the pharynx moves around slowly and independently for roughly 10 hours before losing mobility. The autonomic pharynx moved toward the edge of the oyster shell and increases the frequency at which the oyster or clam opens and closes compared to the control group. The passageway demonstrates negative phototactic behavior in petri dishes. Linear regression showed a positive correlation between the number of autonomic pharynges and the clam mortality rate. Histological dissections showed that clam mantle tissue is externally digested by the autonomic pharynx. The fragments of multi-branched ruffled pharynx from polyclad flatworms slowly detach and play a critical role during the period of the attack on bivalves.