The physiological response of the Arctic key species, Boreogadus saida, to environmental hypoxia: critical oxygen level and swimming performance

Since the beginning of the industrialization, uncontrolled greenhouse gas emission led to a distinct temperature increase on earth. Arctic environments are projected to experience the most severe changes due to climate change. Higher atmospheric temperatures caused already various environmental changes, for example a decrease in Arctic sea ice of 49 % (1979-2000) and increasing carbon dioxide concentrations which reduced the sea surface pH. A reduced sea ice formation will strengthen the summer stratification of warm, oxygen poor on top of cold, oxygen rich water masses, which may consequently cause local hypoxia in ground water layers. As a result, the deep cold water layers do not receive oxygen-rich water and oxygen consumption extends over more than one season. This can lead to local hypoxia in the ground water layers of the protected fjords. Especially endangered of this long-lasting stratification in winter are the deep fjord systems of the Svalbard archipelago. In this region, the change of winter temperatures from 1961–90 corresponded to an increase of 0.6 °C per decade. Corresponding, an additional increase of 0.9 °C per decade is projected for 2071–2100. Thus, the present study investigates the hypoxia tolerance of Polar cod, Boreogadus saida, one of the main Arctic key species. Therefore, different performance parameters were determined. The respiratory capacity as well as the swimming performance under declining oxygen concentrations were measured in two different experimental setups. A sample size of 30 Polar cod with similar body length and weight were chosen. All individuals were used several times during the experiments. First, the routine (RMR) and standard metabolic rate (SMR) were determined via flow-through respirometry. The calculated SMR for Polar cod accounted 0.44 μmol O2/g∙h. The RMR followed an oxygen regulating pattern, indicating that aerobic metabolic pathways such as lipid oxidation were used, rather than anaerobic pathways. This implies a relatively small contribution of anaerobic metabolism to the energy production in B. saida. This was confirmed in the swim tunnel experiments. However, Ugait (the speed at which the fish changed to anaerobically fuelled swimming) was not significantly affected by hypoxia, the total number of bursts (p = 0.025) and total active swimming time (p = 0.017) significantly decreased with decreasing oxygen saturation. The loss of anaerobic swimming capacity due to hypoxia may endanger this species in regard to predator-prey-interactions and loss of escape reactions. Under exercise Polar cod was able to up-regulate its maximum metabolic rate (MMR) until a threshold of 45 % PO2 was reached. Afterwards, the oxygen consumption significantly decreased with decreasing oxygen concentrations. Throughout both experiments neither RMR nor MMR decreased below SMR level. Furthermore, the present study revealed that Polar cod is an extremely hypoxia tolerant fish species, which is able to handle oxygen saturations down to a Pcrit of 4.81 % PO2. This outstanding capability could give the otherwise rather disadvantaged fish species an advantage under changing climate conditions

The physiological response of an Arctic key species Polar cod, Boreogadus saida, to environmental hypoxia: critical oxygen level and swimming performance

Since the beginning of the industrialization, uncontrolled greenhouse gas emission led to a distinct temperature increase on earth. Arctic environments are projected to experience the most severe changes due to climate change. Higher atmospheric temperatures caused already various environmental changes, for example a decrease in Arctic sea ice of 49 % (1979-2000) and increasing carbon dioxide concentrations which reduced the sea surface pH. A reduced sea ice formation will strengthen the summer stratification of warm, oxygen poor on top of cold, oxygen rich water masses, which may consequently cause local hypoxia in ground water layers. As a result, the deep cold water layers do not receive oxygen-rich water and oxygen consumption extends over more than one season. This can lead to local hypoxia in the ground water layers of the protected fjords. Especially endangered of this long-lasting stratification in winter are the deep fjord systems of the Svalbard archipelago. In this region, the change of winter temperatures from 1961–90 corresponded to an increase of 0.6 °C per decade. Corresponding, an additional increase of 0.9 °C per decade is projected for 2071–2100. Thus, the present study investigates the hypoxia tolerance of Polar cod, Boreogadus saida, one of the main Arctic key species. Therefore, different performance parameters were determined. The respiratory capacity as well as the swimming performance under declining oxygen concentrations were measured in two different experimental setups. A sample size of 30 Polar cod with similar body length and weight were chosen. All individuals were used several times during the experiments. First, the routine (RMR) and standard metabolic rate (SMR) were determined via flow-through respirometry. The calculated SMR for Polar cod accounted 0.44 μmol O2/g∙h. The RMR followed an oxygen regulating pattern, indicating that aerobic metabolic pathways such as lipid oxidation were used, rather than anaerobic pathways. This implies a relatively small contribution of anaerobic metabolism to the energy production in B. saida. This was confirmed in the swim tunnel experiments. However, Ugait (the speed at which the fish changed to anaerobically fuelled swimming) was not significantly affected by hypoxia, the total number of bursts (p = 0.025) and total active swimming time (p = 0.017) significantly decreased with decreasing oxygen saturation. The loss of anaerobic swimming capacity due to hypoxia may endanger this species in regard to predator-prey-interactions and loss of escape reactions. Under exercise Polar cod was able to up-regulate its maximum metabolic rate (MMR) until a threshold of 45 % PO2 was reached. Afterwards, the oxygen consumption significantly decreased with decreasing oxygen concentrations. Throughout both experiments neither RMR nor MMR decreased below SMR level. Furthermore, the present study revealed that Polar cod is an extremely hypoxia tolerant fish species, which is able to handle oxygen saturations down to a Pcrit of 4.81 % PO2. This outstanding capability could give the otherwise rather disadvantaged fish species an advantage under changing climate conditions

Neonatal Abstinence Syndrome: Eat, Sleep, Console vs Methadone

In addressing the growing rates of newborn admissions with neonatal abstinence syndrome the following evidence-based PICOT question was addressed: In neonates with neonatal abstinence syndrome, how effective is methadone compared to the eat, sleep, console model in controlling withdrawal symptoms during the postnatal period? The high rate of opioid use across the United States has directly impacted the growing incidence rate of neonatal abstinence syndrome. Diagnoses in the United States have increased from 1.2 per 1000 births in 2000 to 5.8 per 1000 births in 2012 and are still growing (Grossman et al., 2018). Due to this dramatic increase, the need for effective treatment of neonatal abstinence syndrome is more necessary than ever. A search for research articles was conducted within CINAHL and JORGNN using the terms and phrases “eat, sleep, console,” “methadone,” “neonatal abstinence syndrome,” “NAS,” and “substance use outcomes.” Search criteria required all research articles to have been published between 2017 and 2022. Articles that did not discuss the treatment of neonatal abstinence syndrome were excluded. 12 articles were chosen that fell within the search criteria. Research suggests that the eat, sleep, and console method decreases the length of stay in the hospital, decreases the use of pharmaceuticals, and is more effective in treating newborns with neonatal abstinence syndrome

Social Networks, Neighborhood Effects, and Credit Access: Evidence from Rural Guatemala

We measure the extent to which social networks determine sources of credit from a survey of 465 households in western Guatemala. We estimate correlated, contextual and endogenous effects of networks at the neighborhood, church, and village levels, finding that church networks display endogenous effects in credit access. We calculate an elasticity of social imitation (ESI) indicating if the percentage of people accessing microfinance in a church network doubles, the probability of an individual household accessing microfinance increases by 14.1 percent, a magnitude similar to our estimated ESIs for televisions and cell phones within church and neighbor networks

Skill assessment of models relevant for the implementation of ecosystem-based fisheries management

The advance of ecosystem-based fisheries management worldwide has made scientific advice on fisheries related questions more complex. However, despite the need to take interactions between fish stocks, and between stocks and their environment into account, multispecies and ecosystem models are still hardly used as a basis for fishery advice. Although reasons are numerous, the lack of high-level guidance for target-oriented skill assessments of such models contributes to the mistrust to use such models for advice. In this study, we propose a framework of guiding questions for a pragmatic and target-oriented skill assessment. The framework is relevant for all models irrespective of their complexity and approach. It starts with general questions on the advice purpose itself, the type of model(s) and data available for performance testing. After this, the credibility of the hindcasts are evaluated. A special emphasis is finally put on testing predictive skills. The skill assessment framework proposed provides a tool to evaluate a model's suitability for the purpose of providing specific advice and aims to avoid the bad practice of incomplete skill assessments. In the case of multiple models available, it can facilitate the evaluation or choosing of the best model(s) for a given advice product and intends to ensure a level playing field between models of different complexities. The suite of questions proposed is an important step to improve the quality of advice products for a successful implementation of ecosystem-based fisheries management

Naivasha as a development hub : What are relevant problems related to ongoing developments in Naivasha?

“It gives a feeling of security, when everyone is on board!” (Employee of NGO in Naivasha) Naivasha is known as an economic hub due to its flourish flower industry and divers landscape with the Lake Naivasha and several national parks in the area. Nevertheless, Naivasha struggles of socio-economic development and the fast population increase has reinforced it. A large number of international, regional and local non-governmental institutions (NGI) are working in Naivasha for a long time. Non-governmental institutions include all kinds of organizations who are working in the field of development, including non-governmental organizations (NGOs), FBIs, CBOs and many more. With this high density of NGIs in Naivasha, the question comes up, how these institutions coordinate their work to be efficient. Thereby, it is also important to take into consideration the cooperation with the sub-county of Naivasha, who is responsible for their coordination of government bodies. Therefore, the following main question will be asked: How is the cooperation of non-governmental institutions amongst themselves and the sub-county of Naivhasha’s administration? To get an overview of existing cooperations and also to get a better understanding of the meaning of cooperations with their benefits and challenges in Naivasha, the following four guiding questions will structure the research. 1. What cooperation and organization exist amongst non-governmental institutions and the sub-county? 2. What are the achievements of the cooperation amongst non-governmental institutions and the sub-county? 3. What are the challenges of these cooperations? 4. What are the expectations for existing and future cooperations? The research should give an idea, how the work of development cooperation is organized and structured in Naivasha. To answer these questions, several interviews with different non-governmental institutions and one interview with the Department of Social Development of the sub-county will be carried out

ART Suppresses Plasma HIV-1 RNA to a Stable Set Point Predicted by Pretherapy Viremia

Current antiretroviral therapy is effective in suppressing but not eliminating HIV-1 infection. Understanding the source of viral persistence is essential for developing strategies to eradicate HIV-1 infection. We therefore investigated the level of plasma HIV-1 RNA in patients with viremia suppressed to less than 50–75 copies/ml on standard protease inhibitor- or non-nucleoside reverse transcriptase inhibitor-containing antiretroviral therapy using a new, real-time PCR-based assay for HIV-1 RNA with a limit of detection of one copy of HIV-1 RNA. Single copy assay results revealed that >80% of patients on initial antiretroviral therapy for 60 wk had persistent viremia of one copy/ml or more with an overall median of 3.1 copies/ml. The level of viremia correlated with pretherapy plasma HIV-1 RNA but not with the specific treatment regimen. Longitudinal studies revealed no significant decline in the level of viremia between 60 and 110 wk of suppressive antiretroviral therapy. These data suggest that the persistent viremia on current antiretroviral therapy is derived, at least in part, from long-lived cells that are infected prior to initiation of therapy

Lessons for fisheries management from the EU cod recovery plan

The performance of the EU long-term management plan for cod stocks, in force since 2009, is analysed focusing on the human and institutional factors. The plan operates through landings quotas (TACs) and effort restrictions following a Harvest Control Rule, and deploys a novel instrument allowing Member States to ‘buy back’ or increase fishing effort for fleet segments engaged in cod-avoidance measures. The stipulated fishing mortality reductions have not been achieved. On the positive side, the ‘buy-back’ instrument has led to increased uptake of selective gear and implementation of permanent and real- time temporary closures. On the negative side, ignoring the dimension of fishers as reactive agents in the design, the impact assessment, and the annual implementation of the measures has contributed to the failure to adequately implement the plan and achieve its objectives.JRC.G.4-Maritime affair