The aquaculture supply chain in the time of covid-19 pandemic: Vulnerability, resilience, solutions and priorities at the global scale.

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.

Metabolomic analysis of heat-hardening in adult green-lipped mussel (Perna canaliculus): A key role for succinic acid and the GABAergic synapse pathway.

We evaluated the thermotolerance (LT50) of adult green-lipped mussels (Perna canaliculus) following an acute thermal challenge in the summer of 2012 and the winter of 2013. Mussels were grouped into two treatments, naïve (N, no prior heat treatment) and heat-hardened (HH = 1 h at 29 °C, 12 h recovery at ambient) before being immersed for 3 h in water of varying temperature, i.e. Ambient (Control), 25, 29, 31, 33, and 35 °C with subsequent mortality monitored for 30 days. As expected, naïve mussels were less thermotolerant than heat-hardened i.e. Summer LT50, N = 31.9, HH = 33.5 °C; Winter LT50, N = 31.4, HH = 33.8 °C. Moreover, at 33 °C no heat-hardened mussels died compared to 100% mortality in naïve specimens. At 35 °C all mussels died regardless of treatment. For the 'Summer' mussels, metabolite abundances in gill tissues of both naïve and heat-hardened mussels were quantified. For mussels at 33 °C, succinic acid was significantly higher in naïve mussels than heat-hardened mussels, indicating perturbations to mitochondrial pathways in these thermally stressed mussels. Additionally, analysis of biochemical pathway activity suggested a loss of neural control i.e. significantly reduced GABAergic synapse activity, in naïve vs. heat-hardened mussels at 33 °C. Taken together these findings suggest that heat-hardening improves mussel survival at higher temperatures by delaying the onset of cellular anaerobic metabolism, and by maintaining inhibition of neural pathways. Such results offer new perspectives on the complex suite of sub-cellular stress responses operating within thermally stressed organisms.

The role of body surfaces and ventilation in gas exchange of the abalone, Haliotis iris.

The archaeogastropod Haliotis iris possesses paired bipectinate gills and normally four to six shell holes. In still water, endogenous water flow entered the branchial chamber anteriorly to the left of the head and was exhaled primarily from the three most posterior holes. The first or second anterior aperture was occasionally weakly inhalant. Cardiac interaction superimposed an oscillatory component upon ciliary ventilation but did not augment mean flow. At normal endogenous flow rates 49% of oxygen was extracted from the branchial flow, increasing to 71% at lower flows. In still water, normoxic M(O(2)) was 0.47 micromol g(-1) h(-1). Oxyregulation occurred down to P(O(2)) approximately 80 Torr, with partial oxyregulation down to 45 Torr (P (crit)), and oxyconformity below this. The oxyregulatory plateau was absent in artificially ventilated animals but normoxic M(O(2)) was higher (0.65 micromol g(-1) h(-1)). Endogenous ventilation was unaffected by hypoxia to 15 Torr. Heart rate decreased by approximately 20% at 26 Torr before falling more steeply. Oxygen uptake from the branchial ventilation stream fully accounted for normoxic M(O(2)). In hypoxia (<30 Torr), no uptake occurred from the head or foot despite extensive eversion of the epipodium. Blood oxygen measurements excluded the right mantle as a significant gas exchange organ. Changes in oxygen uptake caused by changes in the velocity of external water currents support the concept of induced ventilation and suggest that in still water aerobic respiration was ventilation-limited. Although ciliary ventilation appears adequate to support resting aerobic metabolism, induced ventilation may provide increased aerobic scope for activity and repayment of oxygen debt.