The rapid, global spread of COVID-19, and the measures intended to limit or slow its propagation, are having major impacts on diverse sectors of society. Notably, these impacts are occurring in the context of other anthropogenic-driven threats including global climate change. Both anthropogenic stressors and the COVID-19 pandemic represent significant economic challenges to aquaculture systems across the globe, threatening the supply chain of one of the most important sources of animal protein, with potential disproportionate impacts on vulnerable communities. A web survey was conducted in 47 countries in the midst of the COVID-19 pandemic to assess how aquaculture activities have been affected by the pandemic, and to explore how these impacts compare to those from climate change. A positive correlation between the effects of the two categories of drivers was detected, but analysis suggests that the pandemic and the anthropogenic stressors affect different parts of the supply chain. The immediate measurable reported losses varied with aquaculture typology (land vs. marine, and intensive vs. extensive). A comparably lower impact on farmers reporting the use of integrated multitrophic aquaculture (IMTA) methods suggests that IMTA might enhance resilience to multiple stressors by providing different market options under the COVID-19 pandemic. Results emphasize the importance of assessing detrimental effects of COVID-19 under a multiple stressor lens, focusing on areas that have already locally experienced economic loss due to anthropogenic stressors in the last decade. Holistic policies that simultaneously address other ongoing anthropogenic stressors, rather than focusing solely on the acute impacts of COVID-19, are needed to maximize the long-term resilience of the aquaculture sector.
The COVID-19 global pandemic has had severe, unpredictable and synchronous impacts on all levels of perishable food supply chains (PFSC), across multiple sectors and spatial scales. Aquaculture plays a vital and rapidly expanding role in food security, in some cases overtaking wild caught fisheries in the production of high-quality animal protein in this PFSC. We performed a rapid global assessment to evaluate the effects of the COVID-19 pandemic and related emerging control measures on the aquaculture supply chain. Socio-economic effects of the pandemic were analysed by surveying the perceptions of stakeholders, who were asked to describe potential supply-side disruption, vulnerabilities and resilience patterns along the production pipeline with four main supply chain components: a) hatchery, b) production/processing, c) distribution/logistics and d) market. We also assessed different farming strategies, comparing land- vs. sea-based systems; extensive vs. intensive methods; and with and without integrated multi-trophic aquaculture, IMTA. In addition to evaluating levels and sources of economic distress, interviewees were asked to identify mitigation solutions adopted at local / internal ( i.e., farm-site) scales, and to express their preference on national / external scale mitigation measures among a set of a priori options. Survey responses identified the potential causes of disruption, ripple effects, sources of food insecurity, and socio-economic conflicts. They also pointed to various levels of mitigation strategies. The collated evidence represents a first baseline useful to address future disaster-driven responses, to reinforce the resilience of the sector and to facilitate the design reconstruction plans and mitigation measures, such as financial aid strategies.
The growth of the juvenile sea cucumber, Holothuria scabra, was studied under captivity to elucidate the growth variation pattern and determine the best-fit growth model to estimate age-and size-specific growth rates. Individual growth was extremely variable, with some individuals below the mean initial weight and some expanding their original body length (L) and weight (W) by up to 6.4 and 156 times, respectively; during 84 days of culture starting at 127 days of age. Some of the smallest individuals showed a higher condition factor than larger individuals in the presence of ample food, indicating that lack of food may not be the only impediment to growth. Among the three growth models compared (von Bertalanffy, Gompertz and logistic), the Gompertz model was considered optimal to express H. scabra growth; both in L and W. The age-and size-specific daily growth rate for L and W up to 365 days of age, as estimated by the Gompertz model, had a range of two and nine orders of magnitude in L (0.035 -0.96 mm/day) and W (3.4 × 10 -7 -3.5 g/day), respectively. Use of the Gompertz model over the linear model, which tends to overestimate growth rates, is encouraged to estimate the growth of H. scabra more accurately.
The ability of Holothuria scabra to digest nutrients, such as organic matter (OM), protein and carbohydrate from animal and plant feed ingredients was investigated. Four test feeds prepared by mixing sand with single ingredients from animal sources (shrimp and mussel) and plant sources (diatom and seaweed) were fed to H. scabra to estimate apparent digestibility coefficient (ADC). The total assimilated nutrient (TAN) increased with ADC, whereas ingestion rate (IR) varied slightly among the feeds suggesting that ADC might be a good indicator of nutrient availability to H. scabra. The ADC OM of shrimp and mussel was significantly higher than that diatom and seaweed: 86.2%, 77.1%, 55.1% and 32.3% respectively. ADC protein was similar for shrimp (88.7%), mussel (84.8%) and diatom (75.2%), but significantly lower in seaweed (34.4%). ADC carbohydrate was similar in mussel (58.5%) and diatom (58.3%) as well as in seaweed (31.6) and shrimp (28.0%). ADC protein was relatively higher than ADC carbohydrate suggesting that H. scabra generally digests more protein than carbohydrate. Furthermore, results indicated that nutrients from animal-based feeds are more efficiently digested by H. scabra; thus, animal ingredients rich in easily digestible protein could potentially provide an efficiently balanced diet for H. scabra fed with diatom containing high easily digestible carbohydrate.
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