Susanne P. Eriksson

Evidence for complete denitrification in a benthic foraminifer

Benthic foraminifera are unicellular eukaryotes found abundantly in many types of marine sediments. Many species survive and possibly reproduce in anoxic habitats, but sustainable anaerobic metabolism has not been previously described. Here we demonstrate that the foraminifer Globobulimina pseudospinescens accumulates intracellular nitrate stores and that these can be respired to dinitrogen gas. The amounts of nitrate detected are estimated to be sufficient to support respiration for over a month. In a Swedish fjord sediment where G. pseudospinescens is the dominant foraminifer, the intracellular nitrate pool in this species accounted for 20% of the large, cell-bound, nitrate pool present in an oxygen-free zone. Similarly high nitrate concentrations were also detected in foraminifera Nonionella cf. stella and a Stainforthia species, the two dominant benthic taxa occurring within the oxygen minimum zone of the continental shelf off Chile. Given the high abundance of foraminifera in anoxic marine environments, these new findings suggest that foraminifera may play an important role in global nitrogen cycling and indicate that our understanding of the complexity of the marine nitrogen cycle is far from complete.

Uptake, accumulation and regulation of managanese during experimental hypoxia and normoxia by the decapod Nephrops norvegicus (L.)

A consequence of eutrophication in marine coastal waters is the increased oxygen demand of the sediments. This has resulted in repeated autumnal hypoxia of the bottom waters in many areas and an enhanced flux of manganese (Mn) from the sediment to the overlying waters. Manganese accumulation, subsequent uptake and regulation in the Norway lobster, Nephrops norvegicus, have been investigated. Nephrops norvegicus were continuously exposed for 2 weeks to 555, 1755 and 5555 μg l -1 manganese in combination with hypoxia (2.8-3.2 kPa) or normoxia. Net accumulation occurred in animals exposed to concentrations of 1755 μg l -1 Mn and higher. Accumulation was greatest in gills and haemolymph and least in muscle tissue. The oxygen level had no effect on the accumulation of bioavailable manganese or copper distribution in any tissue of N. norvegicus. In short term experiments using labelled manganese ( 54 Mn) lobsters were exposed to 100 μg Mn l -1 for up to 72 h. The results confirmed that haemolymph and gills were the main target tissues. Urine Mn excretion after pre-exposure to 100 μg Mn l -1 was constant in animals allowed to excrete into clean water for an additional 5 days.

Does the development of respiratory regulation always accompany the transition from pelagic larvae to benthic fossorial postlarvae in the Norway lobster Nephrops norvegicus (L.)

Abstract The ability to regulate O 2 uptake during exposure to acutely declining P O 2 s co-occurred with metamorphosis from a planktonic to a benthic existence in the Norway lobster Nephrops norvegicus when cultured under normoxic conditions in the laboratory. The onset of this regulation appears to be related to the presence of a hypoxia-related hyperventilation of extrabranchial exchange surfaces (telson/uropods) by the pleopods and a shift from a low to a high Hc O 2 affinity. This co-occured with a dramatic calcification of the exoskeleton at metamorphosis, which will restrict gas exchange over the general body surface. Evidence marshalled here points to a shift from a pleopod-based, hypoxia-related, hyperventilation of the uropods/telson as gas exchange surfaces to, in later postlarval stages, a scaphognathite-based response, where the gills are the main areas for gas exchange. This is the first time that experimental evidence has been put forward for the use of uropods/telson by larval lobsters as extrabranchial gas exchange surfaces. Pre-exposure of larval and postlarval N. norvegicus to reduced P O 2 , both in the laboratory and in the field, resulted in the “adult” pattern of M O 2 regulation present during exposure to declining P O 2 being established before metamorphosis. Bringing the ontogeny of this regulation forward in the development itinerary was to some extent a result of a shift from a low to a high Hc O 2 affinity well before metamorphosis and an increase in the magnitude of the hypoxia-related hyperventilatory response in the planktonic larval stages. Thus, the development of respiratory regulation does not always accompany the transition from pelagic larvae to benthic fossorial larvae in N. norvegicus as its onset can be influenced prevailing O 2 conditions, both in the laboratory and the field.

Accumulation and elimination kinetics of manganese from different tissues of the Norway Lobster Nephrops norvegicus (L.)

Abstract The exposure of marine benthic animals to dissolved manganese (Mn) occurs from metalliferous outlets or the enhanced flux of dissolved manganese from sediments during hypoxia. A prerequisite to valid interpretation of manganese concentrations measured in animals in situ is a thorough understanding of accumulation and elimination rates of this metal by relevant target tissues in organisms exposed to environmentally realistic manganese concentrations. Norway lobster, Nephrops norvegicus, accumulated manganese when exposed to solutions of

Effects of copper and hypoxia on two populations of the benthic amphipod Corophium volutator (Pallas)

The effects of elevated copper concentrations and oxygen deficiency on total body copper concentration, egg-production and mortality of two genetically separated populations of Corophium volutator were studied. The amphipods were exposed for 14 days to a three-level factorial design of <0.1, 50 and 100 μg Cul−1 in seawater combined with normoxia, moderate hypoxia (29% oxygen saturation) and hypoxia (19% oxygen saturation). Exposure to copper resulted in a significant (P < 0.01) increase in total body copper concentrations with a concomitant lowering of egg-production (P < 0.05). Results show C. volutator to be a net accumulator of copper, and copper exposure resulted in a lowered reproductive success rate. Mortality was higher (P = 0.05) at low oxygen saturations. The amphipods responded to low oxygen saturations (below 30%) by constructing mud tubes protruding from the sediment surface. Such an adaptation to oxygen depletion at the sediment-water interface might serve to raise the amphipods higher into the water column where water is more likely to be oxygenated. No differences were found between the two populations for any of the three variables measured.

Manganese in the haemolymph and tissues of the Norway lobster, Nephrops norvegicus (L.), along the Swedish west coast, 1993–1995

Spatial and temporal differences in manganese levels in Norway lobsters, Nephrops norvegicus, were compared with the concentrations of manganese in their environment. Animals were collected twice yearly (spring and autumn) from seven stations along the Swedish west coast and from one site in the Faroe Islands, during 1993–94, and analysed for manganese tissue concentration and content. Animals were also collected from the Swedish stations in the autumn of 1995 and compared with animals from a stressful environment, frequently exposed to hypoxia.

Supplementation with fatty acids influences the airway nitric oxide and inflammatory markers in patients with cystic fibrosis.

Objectives: To obtain a balance in the fatty acid (FA) metabolism is important for the inflammatory response and of special importance in cystic fibrosis (CF), which is characterized by impaired FA metabolism, chronic inflammation, and infection in the airways. Nitric oxide (NO) has antimicrobial properties and low nasal (nNO) and exhaled NO (FENO), commonly reported in CF that may affect bacterial status. The present study investigates the effect of different FA blends on nNO and FENO and immunological markers in patients with CF. Patients and Methods: Forty-three patients with CF and “severe” mutations were consecutively enrolled in a randomized double-blind placebo-controlled study with 3 FA blends containing mainly n-3 or n-6 FA or saturated FA acting as placebo. FENO, nNO, serum phospholipid concentrations of FA, and biomarkers of inflammation were measured before and after 3 months of supplementation. Results: Thirty-five patients in clinically stable condition completed the study. The serum phospholipid FA pattern changed significantly in all 3 groups. An increase of the n-6 FA, arachidonic acid, was associated with a decrease of FENO and nNO. The inflammatory biomarkers, erythrocyte sedimentation rate, and interleukin-8 decreased after supplementation with n-3 FA and erythrocyte sedimentation rate increased after supplementation with n-6 FA. Conclusions: This small pilot study indicated that the composition of dietary n-3 and n-6 FA influenced the inflammatory markers in CF. FENO and nNO were influenced by changes in the arachidonic acid concentration, supporting previous studies suggesting that both the lipid abnormality and the colonization with Pseudomonas influenced NO in the airways.

Fatty acid pattern in serum is associated with bone mineralisation in healthy 8-year-old children

Animal studies have shown that fatty acids (FA) are important for normal bone development. Human data are scanty and mostly related to diseases. We hypothesised that serum FA pattern might be related to bone mineralisation in healthy children. Serum phospholipid FA pattern was studied in relation to bone parameters in eighty-five healthy Caucasian 8-year-olds. Dual-energy X-ray absorptiometry and blood sampling for analysis of serum phospholipid FA by capillary GLC were performed on the same day. SFA concentrations were associated with bone mineral density (BMD) of the hip, lumbar spine and total body. There was a general trend that linoleic acid (LA; 18 : 2n-6) was negatively associated with BMD, since that was found both for the LA concentration, the total n-6 concentration and the ratio of n-6:n-3 FA. Arachidonic acid (AA; 20 : 4n-6) was positively correlated with bone mineral content (BMC) and BMD of total body, as was the corresponding z-score and the AA:LA ratio. Both saturated and polyunsaturated serum phospholipid FA were associated with BMC and BMD in healthy children. LA and AA were found to inversely influence bone mineralisation and the association with the n-6:n-3 ratio suggested that this balance might also be of importance. The general trend of a negative influence of high n-6 FA concentrations on bone mineralisation might be of concern in relation to the changes in the Western diet. Longitudinal studies are necessary to verify if different bone compartments and different grades of modelling are related to different FA patterns.

Embryonic response to long-term exposure of the marine crustacean Nephrops norvegicus to ocean acidification and elevated temperature.

Due to anthropogenic CO2 emissions, our oceans have gradually become warmer and more acidic. To better understand the consequences of this, there is a need for long-term (months) and multistressor experiments. Earlier research demonstrates that the effects of global climate change are specific to species and life stages. We exposed berried Norway lobsters (Nephrops norvegicus), during 4 months to the combination of six ecologically relevant temperatures (5–18°C) and reduced pH (by 0.4 units). Embryonic responses were investigated by quantifying proxies for development rate and fitness including: % yolk consumption, mean heart rate, rate of oxygen consumption, and oxidative stress. We found no interactions between temperature and pH, and reduced pH only affected the level of oxidative stress significantly, with a higher level of oxidative stress in the controls. Increased temperature and % yolk consumed had positive effects on all parameters except on oxidative stress, which did not change in response to temperature. There was a difference in development rate between the ranges of 5–10°C (Q10: 5.4) and 10–18°C (Q10: 2.9), implicating a thermal break point at 10°C or below. No thermal limit to a further increased development rate was found. The insensitivity of N. norvegicus embryos to low pH might be explained by adaptation to a pH-reduced external habitat and/or internal hypercapnia during incubation. Our results thus indicate that this species would benefit from global warming and be able to withstand the predicted decrease in ocean pH in the next century during their earliest life stages. However, future studies need to combine low pH and elevated temperature treatments with hypoxia as hypoxic events are frequently and increasingly occurring in the habitat of benthic species.

Effects of contaminants in roundnose grenadier (coryphaenoides rupestris) and Norway lobster (nephrops norvegicus) and contaminant levels in mussels (mytilus edulis) in the skagerrak and kattegat compared to the faroe islands

Abstract In situ biomonitoring of roundnose grenadier (Coryphaenoides rupestris) and Norway lobster (Nephrops norvegicus) and measurements of pollutants levels in caged common mussel (Mytilus edulis) were used to assess the environmental impact of contaminants in the Skagerrak and Kattegat and near the Faroe Islands. By comparing the responses of a suite of established and potential biomarkers, i.e. different liver detoxification enzymes and histopathology in roundnose grenadier in the Skagerrak, and at a reference site off the Faroe Islands, evidence was found that the deeper parts of the Skagerrak are affected by anthropogenic contaminants. Levels of polycyclic aromatic hydrocarbons (PAH) and organochlorines in caged mussels were compared with those sediment. The Skagerrak/Kattegat area was found to be more polluted than the Faroe area and the caged mussels bioaccumulated the PAHs to a higher degree than the organochlorines. This seems to indicate that the PAHs in the sediments are more bioavailable than the organochlorines and that the induced ethoxyresorufin-O-deethylase activities observed in Skagerrak roundnouse grenadier may be due to PAH exposure. The Norway lobster accumulated manganese to various degrees in the different parts of the organism. The excretion rate of manganese could not cope with the uptake rate at higher exposure concentrations. Enhanced manganese concentrations, especially in the gills and haemolymph, seem to be a useful indication of increased manganese levels in the water. Hypoxia makes a sediment-bound manganese much more bioavailable. The elevated levels of manganese in Norway lobster from the Skagerrak/Kattegat area therefore seem to reflect the increasing occurrence of hypoxic conditions in the Kattegat and coastal areas of the Skagerrak. Accumulated manganese in Norway lobster may thus serve as a biomarker of hypoxia. In conclusion, the use of a suite of different biomarkers in ecotoxicological and ecophysiological studies and analyses of contaminant levels have provided evidence of a large-scale environmental impact of pollutants and nutrients in the Skagerrak/Kattegat area. This should lead to further efforts to decrease transport into and deposition of waste compounds in the sea.