Strong Influence of Baseline Respiration in an Oligotrophic Coastal Ecosystem

Respiration is a key metabolic process in the marine environment and contemporary phytoplankton production (PhP) is commonly assumed the main driver. However, respiration in the absence of contemporary PhP, termed baseline respiration, can influence the energetics of an ecosystem and its sensitivity to hypoxia. Direct studies of baseline respiration are currently lacking. This study aims to obtain a first estimate of baseline respiration in a sub-arctic estuary and determine its contribution to plankton community respiration. Three approaches used to define baseline respiration determined the average rate to be 4.1 ± 0.1 (SE) mmol O2 m–3 d–1. A hypsographic model at the basin scale accounting for seasonal variation estimated an annual contribution of 30% baseline respiration to planktonic respiration. There was no correlation between plankton respiration and PhP, but a significant linear dependence was found with the total carbon supply from phytoplankton and riverine input. The sum of dissolved organic carbon transported by rivers, provided by both benthic and pelagic algae, could sustain 69% of the annual plankton respiration, of which as much as 25% occurred during winter. However, only 32% of the winter season respiration was explained, indicating that unknown carbon sources exist during the winter. Nitrification had a negligible (≤2.4%) effect on baseline respiration in the system. The results show that baseline respiration accounted for a significant percentage of coastal plankton respiration when allochthonous sources dominated the carbon supply, weakening the respiration-to- PhP relationship

How the utilised SOC window in commercial Li-ion pouch cells influence battery ageing

In many lithium-ion battery (LIB) applications, e.g. hybrid vehicles and load-levelling storage systems, only part of the state-of-charge (SOC) range needs to be utilised. This offers the possibility to use an optimal SOC window to avoid LIB ageing. Here, a large test matrix is designed to study LIB ageing in a commercial 26 Ah pouch cell, in order to map the ageing behaviour at different SOC levels with respect to temperature and current. A quantification of the degradation modes, loss of lithium inventory (LLI), loss of active positive (LAM(PE)) and negative (LAM(NE)) electrode materials is made by analysing the change in the open circuit voltage (OCV). A key result is that lower SOC intervals significantly improved battery ageing. Even during harsh test conditions, such as high Crates and temperatures, the cells deliver more than three times the expected number of full cycle equivalents. High SOC combined with high C-rate increase ageing where the dominating ageing mechanisms are LLI, followed by LAM(PE)

Marine Strategy Framework Directive - Task Group 4 Report Food Webs

The Marine Strategy Framework Directive (2008/56/EC) (MSFD) requires that the European Commission (by 15 July 2010) should lay down criteria and methodological standards to allow consistency in approach in evaluating the extent to which Good Environmental Status (GES) is being achieved. ICES and JRC were contracted to provide scientific support for the Commission in meeting this obligation. A total of 10 reports have been prepared relating to the descriptors of GES listed in Annex I of the Directive. Eight reports have been prepared by groups of independent experts coordinated by JRC and ICES in response to this contract. In addition, reports for two descriptors (Contaminants in fish and other seafood and Marine Litter) were written by expert groups coordinated by DG SANCO and IFREMER respectively. A Task Group was established for each of the qualitative Descriptors. Each Task Group consisted of selected experts providing experience related to the four marine regions (the Baltic Sea, the North-east Atlantic, the Mediterranean Sea and the Black Sea) and an appropriate scope of relevant scientific expertise. Observers from the Regional Seas Conventions were also invited to each Task Group to help ensure the inclusion of relevant work by those Conventions. This is the report of Task Group 4 Food Webs.JRC.DDG.H.5-Rural, water and ecosystem resource

Melatonin secretion and excretion : a clinical study focusing on factors and disease states which might influence melatonin

The overall aim of this thesis was to find out whether other factors than the the light-dark changes influence the function of the pineal gland. Since melatonin (MT) itself, or its precursor serotonin, are of importance for sleep, mood, and pain perception, disease states - or situations in which these functions are disturbed - should be of interest to investigate in this context. Altogether 100 individuals (51 men and 49 women) participated in the study. Seventy were healthy volunteers and 30 were patients: 7 with Wernicke-Korsakoff syndrome (WKS), 9 with Obstructive Sleep Apnea Syndrome (OSAS), 8 with Fibromyalgic Syndrome (FMS), and 6 with primary Hypothyroidism. All experiments were carried out during the night (18(20)h-08h). The lights were switched off 23h- 07h. Serum MT concentrations were determined every second hour 18(20)h-08h. Urine was collected between 22h- 07h for determination of urinary MT excretion. I. Acute alcohol intoxication induced mild hypoglychernia and inhibited the nocturnal secretion of NIT by 20-33 % in healthy volunteers. The impaired NIT secretion could not have been caused by reduced glucose provision, since oral glucose supplementation during alcohol ingestion prevented the alcohol-induced hypoglychernia but still did not normalize MT secretion. II. Also patients with WKS, caused by chronic alcohol abuse, had a markedly reduced nocturnal secretion of MT. III. Acute exogenous hypercalcemia decreased the nocturnal MT secretion by 20 % in healthy subjects. Calcium antagonism, in the form of oral verapamil, had no significant influence on MT secretion in normal individuals. It also failed to affect urinary excretion of 6-sulphatoxy-MT, the main MT metabolite in the urine. By contrast, verapamil increased urinary excretion of unchanged MT by 67-145 %, This suggests that verapamil may alter the renal excretion of NIT and/or change the hepatic metabolism of the hormone. IV. Patients with OSAS usually complain of sleep disturbances and/or daytime fatigue. Although MT has sleeppromoting properties it is unlikely that the problems OSAS-patients report are caused by changed MT secretion, because this study showed that neither the nocturnal MT secretion nor the urinary MT excretion were different in these patients as compared with healthy controls. It also showed that although CPAP treatment efficiently prevented the occurrence of sleep apnea, it did neither influence the nocturnal secretion, nor the urinary excretion of MT. V. Two dominating symptoms in patients with FMS are (besides widespread muscle pain) fatigue and sleep disturbances. This investigation showed that these patients had a 31 % lower MT secretion during the dark part of the night (23-07h) than age-, BMI-, and sex-matched controls. Previous studies have shown that FMS patients have impaired tryptophan/serotonin provision, and a higher frequency of serotonin antibodies, not only when compared with healthy controls, but also when compared with patients with other rheumatic diseases. It is possible that such mechanisms contribute to the impaired MT secretion in this group of patients. VI. Exogenous somatostatin, in the form of subcutaneous injections of octreotide, was without significant influence on nocturnal MT secretion in normal individuals, and in patients with primary Hypothyroidism. This implies that endogenous sornatostatin may not be an important regulator of MT secretion in man

Vattenmassans biologi

En tydlig förändring av djurplanktonsamhällets sammansättning kanvisas för perioden 1994–2001. Hoppkräftor ökade i andel av den totaladjurplanktonbiomassan både i Bottenvikens utsjö och BottenhavetskustzonS1. Främst var det arten Limnocalanusmacrurus som ökade i Bottenviken. I Bottenhavets kustzonökade i stället släktena Acartia och Eurytemora

Miljöanalys av Rånefjärden 1997-2004

Vattenkvaliteten har under åren 1997–2004 undersökts vid tre stationer i Rånefjärdsområdet; Rånefjärden, Gussöfjärden och Fjuksöfjärden. Mätningarna utgör underlag för miljöövervakning av området, och skall användas för återkommande tillståndsbeskrivning. I rapporten föreslås modifi eringar i mätprogrammet, för att kunna uppnå en bättre och säkrare tillståndsbeskrivning och som en anpassning till Europeiska Unionens ramdirektiv för vatten. De föreslagna modifi eringarna omfattar fl er biologiska variabler, harmonisering med befi ntligt utsjöprogram, bättre rumslig täckning och val av mätperioder för anpassning till gällande bedömningsgrunder. Undersökningen visar att Rånefjärdsområdet är ett typiskt kustvattenområde i norra Bottenviken, starkt påverkat av sötvatten. Tillståndet avseende näringsnivå är enligt svenska bedömningsgrunder god i området. De höga halter av ammonium som förekommer är en naturlig karaktär för nordvästra Bottenviken, orsakat av älvburet löst organiskt material med en relativt hög kvävehalt. För kustvatten typiska nivåer för klorofyll-a, bakteriell syrekonsumtion och syrehalt stödjer också att produktiviteten i området ligger på förväntad nivå. Halten av de fl esta näringsämnen och nivån på planktonproduktionen är fl era gånger högre i det undersökta området än i norra Bottenvikens utsjö. Undantag utgör nitrat som visar något högre värden i utsjön, sannolikt som en konsekvens av bakteriell ammonifi ering och nitrifi kation. Det insamlade datamaterialet visar på få signifi kanta trender under 8-årsperioden, vilket tolkas som att näringssituationen varit stabil och endast varierat inom naturliga intervall. De enda signifi kanta trenderna som påvisats är en minskning av halten löst organiskt kol och humus i Gussö- och Fjuksöfjärden. Den minskade transporten av löst organiskt material från Råneälven är en möjlig förklaring till detta. Tidsseriernas förmåga att upptäcka förändringar motsvarade 0.3 till 15 % år -1 beroende på variabel, antaget 80% styrka och 10 år lång dataserie. Transporten av organiskt bundet fosfor från Råneälven har följaktligen också minskat under senare delen av perioden. Tillförseln av fosfor från älven visades styra halterna av både fosfat och totalfosfor i den mest kustnära fjärden. Råneälven har därmed en avgörande betydelse för regleringen av fosfor som begränsande ämne i Rånefjärden. Betydelsen av fosfor som begränsande ämne bekräftas i undersökningen genom snabbt sjunkande fosforhalter i en transekt från kust till utsjö. Halten av kväveföreningar minskar betydligt långsammare. Kvoten mellan kväve och fosfor är hög redan i kustbassängen, där kvoten stämmer väl överens med kvoten i Råneälvens vatten. Mot utsjön ökar värdena till över 100

Regulation of marine plankton respiration: A test of models

Plankton respiration is a major process removing oxygen from pelagic environments and constitutes one of the largest oxygen transformations in the sea. Where the O2 supplies due to dissolution, advection and oxygenic photosynthesis are not sufficient, hypoxic, or anoxic waters may result. Coastal waters with limited water exchange are especially prone to have low oxygen levels due to eutrophication and climate change. To support marine environmental management in a period of rapid climate change, we investigated the current knowledge of regulating plankton respiration based on field and experimental studies reported in the literature. Models for regulation of plankton respiration was tested on a three-year field data set. Temperature is the most reported predictor positively influencing plankton respiration (mean r2 = 0.50, n=15). The organic carbon supply driven by primary production has a similar coefficient of determination but fewer reported relationships (mean r2 = 0.52, n=6). Riverine discharges of dissolved organic carbon can override the influence of primary production in estuaries precluding effects of nutrient reductions. The median predictions of respiration regulation produced by current models vary by a factor of 2 from the median of observed values and extreme values varied even more. Predictions by models are therefore still too uncertain for application at regional and local scales. Models with temperature as predictor showed best performance but deviated from measured values in some seasons. The combined dependence of plankton respiration on temperature, phytoplankton production and discharge of riverine organic carbon will probably lead to increased oxygen consumption and reduced oxygen levels with projected climate change. This will be especially pronounced where increased precipitation is expected to enhance riverine discharges of carbon compounds. The biologically mediated transfer of carbon for long-term storage in deeper layers will slow down. Implementation of plankton respiration measurements in long-term ecological monitoring programs at water body and basin scales is advocated, which would enable future multivariate analyses and improvements in model precision across aquatic environments

Vattenmassans biologi

Inga statistiskt säkerställda förändringar kan påvisas bland de biologiska variabler som speglar näringstillgången i vattenmassan i Bottniska viken. Både växtplanktonarter och syrekonsumtion som redovisas nedan är exempel på detta. Tillsammans med stabila tidsserier av syre och närsalter tyder resultaten på en jämn näringstillgång i Bottniska vikens utsjöbassänger under övervakningsperioden

Importance of Bacterial Maintenance Respiration in a Subarctic Estuary : a Proof of Concept from the Field

Bacterial respiration contributes to atmospheric carbon dioxide accumulation and development of hypoxia and is a critical, often overlooked, component of ecosystem function. This study investigates the concept that maintenance respiration is a significant proportion of bacterial respiration at natural nutrient levels in the field, advancing our understanding of bacterial living conditions and energy strategies. Two river-sea transects of respiration and specific growth rates were analyzed representing low- and highproductivity conditions (by in situ bacterial biomass production) in a subarctic estuary, using an established ecophysiological linear model (the Pirt model) estimating maintenance respiration. The Pirt model was applicable to field conditions during high, but not low, bacterial biomass production. However, a quadratic model provided a better fit to observed data, accounting for the maintained respiration at low μ. A first estimate of maintenance respiration was 0.58 fmol O2 day−1 cell−1 by the quadratic model. Twenty percent to nearly all of the bacterial respiration was due to maintenance respiration over the observed range of μ (0.21– 0.002 day−1 ). In the less productive condition, bacterial specific respiration was high and without dependence on μ, suggesting enhanced bacterial energy expenditure during starvation. Annual maintenance respiration accounted for 58% of the total bacterioplankton respiration based on μ from monitoring data. Phosphorus availability occasionally, but inconsistently, explained some of the remaining variation in bacterial specific respiration. Bacterial maintenance respiration can constitute a large share of pelagic respiration and merit further study to understand bacterial energetics and oxygen dynamics in the aquatic environment