Species and genetic diversity relationships in benthic macroinvertebrate communities along a salinity gradient

BACKGROUND

Species- and genetic diversity can change in parallel, resulting in a species-genetic diversity correlation (SGDC) and raising the question if the same drivers influence both biological levels of diversity. The SGDC can be either positive or negative, depending on whether the species diversity and the genetic diversity of the measured species respond in the same or opposite way to drivers. Using a traditional species diversity approach together with ultra-conserved elements and high throughput sequencing, we evaluated the SGDCs in benthic macrofauna communities in the Baltic Sea, a geologically young brackish water sea characterised by its steep salinity gradient and low species richness. Assessing SGDCs from six focal marine invertebrate species from different taxonomic groups and with differing life histories and ecological functions on both a spatial and temporal scale gives a more comprehensive insight into the community dynamics of this young ecosystem and the extrinsic factors that might drive the SGDCs.

RESULTS

No significant correlations between species diversity and genetic diversity were found for any of the focal species. However, both negative and positive trends of SGDCs for the individual focal species were observed. When examining the environmental drivers, no common trends between the species were found, even when restricting the analysis to specific taxonomic classes. Additionally, there were no common environmental factors driving the diversity relationships for species sharing the same SGDC trend (positive or negative). Local population dynamics, together with the invasion history of the individual species and their unique adaptation to the distinctive environment of the Baltic Sea, are expected to be of major influence on the outcome of the SGDCs.

CONCLUSIONS

The present results highlight the importance of assessing SGDCs using multiple species, not just a single indicator species. This emphasises a need to pay attention to the ecology and life history of the focal species. This study also provides insight into the large differences in both patterns and drivers of genetic diversity, which is important when including genetic biodiversity in conservation plans. We conclude that the effects of environmental and biological factors and processes that affects diversity patterns at both the community and genetic levels are likely species dependent, even in an environment such as the Baltic Sea with strong environmental gradients.

The importance of phospholipids combined with long-chain PUFA in formulated diets for pikeperch (Sander lucioperca) larvae

Dietary phosphoglycerides and n-3 long-chain PUFA (LC-PUFA) play important functions in the development of pikeperch (Sander lucioperca) larvae. This study aimed to determine optimal dietary levels of soyabean lecithin (SBL)-derived phospholipids (PL) in starter feeds for pikeperch larvae 10-30 d post-hatch (DPH) and examine performance and ontogeny by additional supplementation of n-3 LC-PUFA in the form of Algatrium DHA 70 (glyceride product; 660-700 mg/g DHA; EPA 60-75 mg/g). In total, six isoproteic and isoenergetic extruded diets were formulated with increasing levels of PL (3·7, 8·3 or 14·5 % wet weight (w.w.), respectively); however, three of the diets were supplemented with three levels of Algatrium DHA 70 (0·6, 2·0 or 3·4 %, respectively). Liver proteomic analyses of larvae at 30 DPH were included for effects of PL and primarily DHA on performance, physiological expression and interactions in larval proteins. In addition, bone anomalies, digestive enzymatic activity, candidate gene expression and skeleton morphogenesis were examined. Results confirmed the importance of dietary PL levels of at least 8·2 % w.w., and an additional beneficiary effect of supplementation with DHA plus EPA. Thus, combined supplementation of SBL (up to 14·51 % w.w. PL) and n-3 LC-PUFA (1·004 % DM DHA and 0·169 % DM EPA) in the form of TAG resulted in highest growth and lowest incidence of anomalies, improved digestive enzyme activity and had differential effect on liver proteomics. The results denote that essential fatty acids can be supplemented as TAG to have beneficial effects in pikeperch larvae development.

Evaluation of the Myo armband for the classification of hand motions

Pattern recognition-based control systems have been widely investigated in prostheses and virtual reality environments to improve amputees' quality of life. Most of these systems use surface electromyography (EMG) to detect user movement intentions. The Myo armband (MYB) is a wireless wearable device, developed by Thalmic Labs, which enables EMG recordings with a limited bandwidth (<100Hz). The aim of this study was to compare MYB's narrow bandwidth with a conventional EMG acquisition system (CONV) that captures the full EMG spectrum to assess its suitability for pattern recognition control. A crossover study was carried out with eight able-bodied participants, performing nine hand gestures. Six features were extracted from the data and classified by Linear Discriminant Analysis (LDA). Results showed a mean classification error of 5.82 ± 3.63% for CONV and 9.86 ± 8.05% for MYB with no significantly difference (P = 0.056). This implies that MYB may be suitable for pattern recognition applications despite the limitation in the bandwidth.

Temporal genetic structure in a poecilogonous polychaete: the interplay of developmental mode and environmental stochasticity

Background

Temporal variation in the genetic structure of populations can be caused by multiple factors, including natural selection, stochastic environmental variation, migration, or genetic drift. In benthic marine species, the developmental mode of larvae may indicate a possibility for temporal genetic variation: species with dispersive planktonic larvae are expected to be more likely to show temporal genetic variation than species with benthic or brooded non-dispersive larvae, due to differences in larval mortality and dispersal ability. We examined temporal genetic structure in populations of Pygospio elegans, a poecilogonous polychaete with within-species variation in developmental mode. P. elegans produces either planktonic, benthic, or intermediate larvae, varying both among and within populations, providing a within-species test of the generality of a relationship between temporal genetic variation and larval developmental mode.

Results

In contrast to our expectations, our microsatellite analyses of P. elegans revealed temporal genetic stability in the UK population with planktonic larvae, whereas there was variation indicative of drift in temporal samples of the populations from the Baltic Sea, which have predominantly benthic and intermediate larvae. We also detected temporal variation in relatedness within these populations. A large temporal shift in genetic structure was detected in a population from the Netherlands, having multiple developmental modes. This shift could have been caused by local extiction due to extreme environmental conditions and (re)colonization by planktonic larvae from neighboring populations.

Conclusions

In our study of P. elegans, temporal genetic variation appears to be due to not only larval developmental mode, but also the stochastic environment of adults. Large temporal genetic shifts may be more likely in marine intertidal habitats (e.g. North Sea and Wadden Sea) which are more prone to environmental stochasticity than the sub-tidal Baltic habitats. Sub-tidal and/or brackish (less saline) habitats may support smaller P. elegans populations and these may be more susceptible to the effects of random genetic drift. Moreover, higher frequencies of asexual reproduction and the benthic larval developmental mode in these populations leads to higher relatedness and contributes to drift. Our results indicate that a general relationship between larval developmental mode and temporal genetic variation may not exist.

Do inactivated microbial preparations improve life history traits of the copepod Acartia tonsa?

We have tested a microbial preparation with probiotic effects (PSI; Sorbial A/S DANISCO) on the calanoid copepod Acartia tonsa (Dana) development time and reproduction effectiveness in culture. The hypotheses were that PSI increases the productivity and quality of copepods in culture (increased egg production and hatching success, HS). This was carried out because the use of copepods as live prey in aquaculture could increase the number of fish successfully raised through their entire life cycle. However, the availability of copepods is limited by their difficulty to be effectively raised. Our results show that the addition of PSI to the algal food increased the individual size of the adult females and their egg production. The PSI, together with Rhodomonas salina, also increased the HS of the eggs produced by PSI-treated females. These effects were observed despite that the biochemical analysis of the PSI revealed that it is a nutritionally poor food lacking essential fatty acids, and hence it cannot be used alone to raise copepods but instead as a food additive. This is the first demonstration that the effectiveness of copepod culturing can be improved using microbial preparations as a food additive.

Respiration rates of subitaneous eggs from a marine calanoid copepod: monitored by nanorespirometry

The oxygen consumption rate during embryogenesis of Acartia tonsa subitaneous eggs were measured at different temperatures (10, 15, 17, 21, 24 and 28 degrees C) with nanorespirometry. The oxygen consumption was constant during the embryogenesis but increased rapidly at hatching time. The mean +/- SD oxygen consumption rate increased exponentially with temperature and ranged from 0.09 +/- 0.04 (10 degrees C) to 0.54 +/- 0.09 nmol O(2) egg(-1) h(-1) (28 degrees C). The mean +/- SD Q(10)-value was 2.51 +/- 0.15. Calculations of energy consumption during embryogenesis ranged from 1.86 to 18.28 mJ depending on temperature and development time. We conclude that the effect of temperature on oxygen consumption rate was far less important than the prolonged development time when calculating the energy consumed during embryogenesis.

Influence of LAS on marine calanoid copepod population dynamics and potential reproduction

The toxicity of linear alkyl benzene sulfonate (LAS) to marine invertebrates is well documented under laboratory conditions using single-species tests. It is less known how LAS affects natural populations of aquatic organisms. We hypothesised that LAS was more toxic to the calanoid copepod Acartia sp. under natural conditions than Acartia tonsa under cultured conditions in the laboratory. This hypothesis was checked by a direct comparison of LAS toxicity in single-species and model (mesocosm) studies. The acute and sublethal effects of LAS on the survival and egg production of laboratory reared A. tonsa were examined by standard test, i.e. incubation with LAS without food for 24-72 h. The LC(50) and EC(50) values averaged 1.23 and 0.74 mg l(-1) for survival and egg production, respectively. These values are comparable to previous reports. The effects of LAS on a natural copepod community were also investigated under in situ conditions. A series of seven mesocosms (holding approx. 3 m(3) of seawater each) was established with two mesocosms being controls without LAS and five mesocosms with increasing concentrations of LAS ranging from 0.1 to 6.5 mg l(-1) applied as a single dose. The indigenous copepod community, dominated by Acartia sp. and Centropages sp., responded clearly to LAS concentrations above 0.1 mg l(-1). The calculated no effect value was 0.14 mg LAS l(-1) (95% CI=0.08-1.82 mg LAS l(-1)) for the entire copepod community including all development stages after 24 h exposure. The increased sensitivity under in situ conditions was probably promoted by the suboptimal growth conditions, e.g. no saturated food concentration or inadequate nutritive values of the food. The amount of food expressed as chlorophyll concentration was low (around 2 microg chl. a l(-1)) but was not affected by LAS. It appeared that the naupliar stages of Acartia and Centropages were the least affected by LAS and that new cohorts were able to develop 15 days after the dosing with LAS.

Comparing sensitivity of ecotoxicological effect endpoints between laboratory and field

Extrapolating toxicant effects with a fixed application factor (AF) approach or one of the species sensitivity distribution (SSD) models presumes that toxicant effects on single, individual-level endpoints reflect effects at the ecosystem level. Measured effect concentrations on plankton from multispecies field tests using tributyltin (TBT) and linear alkylbenzene sulfonates (LAS) were compared with published laboratory single-species test results and measured in situ concentrations. Extrapolation methods were evaluated by comparing predicted no-effect concentrations (PNECs), calculated by AF and SSD models with NOECs and E(L)C(50)s obtained from field studies. Overall, structural parameters were more sensitive than functional ones. Measured effect concentrations covered approximately the same range between laboratory and field experiments. Both SSD and AF approaches provide PNECs that appear to be protective for ecosystems. The AF approach is simpler to apply than the SSD models and results in PNECs that are no less conservative. Calculated PNEC values and the lowest field effect concentrations were lower than measured environmental concentrations for both substances, indicating that they may pose a risk to marine ecosystems.

Mesocosm study of Mytilus edulis larvae and postlarvae, including the settlement phase, exposed to a gradient of tributyltin

In a mesocosm study, the effects of a gradient of tributylin (TBT) (nominal TBT concentrations of 0.3, 2.3, 18.5, 146, and 1150 ng Sn liter-1) on Mytilus edulis larvae and postlarvae, including the settlement phase, were investigated over 15 days. Effects of TBT on mortality, growth measured as increase in shell length, shell dimensions, and settlement were evaluated. In general, mortality was high in all mesocosms including the control; during the first 24 h of the experiment, mortality was 63% at the highest TBT concentration (26% in the control). An LC50 (24 h) of 254 ng Sn liter-1 was estimated. The mortality rate of larvae/postlarvae increased 40% at 18.5 ng Sn liter-1 (0.41 day-1) compared with the control (0.30 day-1). For postlarvae, the growth rate decreased with increasing TBT concentration. The mean shell length at 2.3 ng Sn liter-1 was significantly reduced in comparison to the control on Day 15. Then EC10 (15 days) for shell growth was estimated to be 5.4 ng Sn liter-1. This is the lowest effect concentration ever reported in the literature. For postlarvae, shell dimensions in terms of shell length-shell width relations were affected by TBT at 1150 ng Sn liter-1, because the reduced growth led to the failure of adult mussels to secret a dissochonch shell. During the first days of exposure, the settlement monitored on polyethylene settling strips was stimulated by TBT, after which the settlement decreased due to the high mortality. Only a small portion of the population survived to the end of the test period. By comparison of the biotic conditions (in terms of larval abundance and particle concentration reflecting larval food) in the control mesocosm with those in the cove where the experiment was conducted, it was concluded that the mesocosm had successfully simulated the field conditions.

Acute illnesses in children. A description and analysis of parents' perception of illness threat

OBJECTIVES

To identify families in which the parents reported the child's illness as particularly stressful (high perception of illness threat), and to find out which health problems the parents perceive as particularly threatening.

DESIGN

The parents registered the diagnosis and perception of illness threat in relation to the child's latest illness within a four-week retrospective period. Selected psychosocial conditions of the families were recorded in the same questionnaire.

SETTING

18,949 families with at least one child under the age of 8 years, resident in the County of Ringkøbing in western Denmark at 1 March 1988.

SUBJECTS

An age-stratified random sample of 1982 families was entered in the study. 85% of the families returned the questionnaire.

RESULTS

There was a considerable variation in the parents' perception of illness threat. On the basis of a score it was possible to group parents with a high, medium, and low perception of illness threat. Every fourth family reported a high perception of illness threat. A multivariate analysis, with a high perception of illness threat as dependent and selected psychosocial conditions and the diagnosis as independent variables, led to the following main results: 1) parents with a high perception of the general health threat ("worried" parents) most frequently reported a high perception of illness threat, 2) the diagnoses were decisive; in particular, inflammation in the middle ear, bronchitis, pneumonia, and accidents led to the parents' reporting a high perception of illness threat, 3) parents without experience of children and children's illnesses more frequently perceived an actual illness as a high illness threat than parents with this experience, 4) parents more frequently perceive an illness in girls as a high illness threat.

CONCLUSIONS

"Worried" parents, without experience of children and children's illnesses, perceive the child's latest illness as a high illness threat. These families need special care.

Acute illnesses in children. A description and analysis of the cumulative incidence proportion

OBJECTIVES

To describe parent-reported morbidity in relation to the psycho-social conditions of the families and to characterize families whose children are frequently ill.

DESIGN

The parent-reported morbidity in a two-month prospective period, and the psychosocial conditions of the families were registered by means of a questionnaire. The conditioned probability of parents' reporting an episode of illness was estimated by means of logistic regression analysis, taking the psycho-social conditions into consideration.

SETTING

18,949 families with at least one child under the age of 8 years, resident in the County of Ringkjøbing in western Denmark at 1 March 1988.

SUBJECTS

An age-stratified random sample of 1982 families was entered in the study. 1588 (82%) families returned the questionnaire.

RESULTS

The parents reported considerable morbidity in their children. The cumulative incidence proportion (CIP) for the period was 48%. The multivariate analysis of the parent-reported morbidity led to the following main results: 1) the morbidity was greatest for children aged 6 to 18 months, after which it decreased with age, 2) there was interaction between the care conditions and the child's age--CIP for children up to two years was largest for the children who were cared for in daycare, while the CIP for the older children was largest for the children who were cared for at home, 3) if the parents reported that the child's siblings suffered from chronic or frequently recurring morbidity, the child's morbidity rate was significantly increased, 4) mothers with higher education reported more morbidity in their children than mothers without this education, and 5) parents with a high perception of the general health threat ("worried" parents) reported more morbidity than did parents with a low perception.

CONCLUSIONS

The results made it possible to characterize families whose children were frequently reported ill.

[The EMLA cream versus placebo in MMR vaccination of older children in general practice]

We investigated the effect of EMLA cream (active ingredients: 25 mg lidocaine and 25 mg prilocaine per gram of cream) on subjective experience of pain in connection with vaccination. The study was conducted as a double-blind, randomized, placebocontrolled trial in a general practice setting. The subjects were ten to fifteen year-olds, who were due to be inoculated with measles-mumps-rubella vaccine. Of the 118 children entering the trial, 117 completed the treatment (EMLA 58, placebo 59). Treatment time was at least 60 minutes for all children. The children reported similar degrees of pain immediately after vaccination in both groups, one third of both treatment and placebo groups reporting medium to strong pain (not significant). On the day after vaccination, more than half the families (59%) said that they would use the cream again in connection with future vaccinations; again, there was no statistically significant difference between the two groups in this respect. Based on these results, we conclude that use of EMLA cream as a topical local anaesthetic does not reduce the experience of pain in connection with the administration of measles-mumps-rubella vaccine to older children.

Subjective distresses of nasogastric tube feeding

Health care professionals assume that tube feeding is an unpleasant, distressing experience for patients, which is only partially substantiated by experience. Thirty patients were interviewed via a tube feeding and hospital experience checklist (a 47-item interview schedule). Common experiences were operationally defined as those felt by at least 50%; subjectively distressful experiences were those identified by patients as causing distress. The most common and most distressful experiences of nasogastric tube feeding were: sensory irritations and sensory deprivation. The psychosensory irritation experiences were: thirst, sore nose or throat, dry mouth, runny nose, a tube in the nose, taking food through a tube, breathing through the mouth, breathing with a tube in the nose, taking food in a treatment type container, and taking food with a different texture and smell than usual. The psychosensory deprivation experiences were: an unsatisfied appetite for certain foods, deprivation of tasting, chewing, swallowing food, and drinking liquids, limited mobility, and deprivation of regular food. Except for burping, gastrointestinal symptoms were not common though they were usually distressful. This information has been used to develop teaching programs which are being tested for effectiveness in reducing distress associated with nasogastric tube feeding.

Synchronous, sustained oscillation of C-peptide and insulin in the plasma of fasting monkeys

The previously reported synchronous oscillations in plasma glucose and insulin levels have been further studied to determine whether the phenomenon can be attributed to cyclic secretion or degradation of the hormone. Plasma C-peptide concentrations were measured and found to cycle with the same period as plasma insulin suggesting that the oscillations of insulin arise from changing secretion rather than degradation. The amplitude of C-peptide oscillation was 50 percent that of insulin. Assuming first order kinetics and the same relative rates of disappearance as in humans, this difference in amplitudes in consistent with equal secretion rates for the two peptides.

Regulation of appetite during total parenteral nutrition

To study effects of total parenteral nutrition (TPN) on appetite, in an effort to obtain an objective assessment of hunger separated from underlying pathology, caloric intake and levels of TPN were measured in two male rhesus monkeys. TPN was found to affect appetite by reducing voluntary food intake. One monkey showed precise regulation of daily oral caloric intake and maintained stable body weight during this period. The other monkey did not show such precise regulation. When TPN was stopped, both continued suppression of oral intake for a time. Implications are discussed.

Effects of enteral and parenteral nutrition on appetite in monkeys

Varied clinical observations of the presence of either hunger or anorexia during intragastric or intravenous alimentation have led to the current experiments. Nine rhesus monkeys (Macaca mulatta) were involved in studies of the long-term effects of enteral and parenteral nutrition on appetite as assessed by feeding behavior and gastric motility. The monkeys received either intragastric infusions of glucose or a complete liquid diet, or intravenous infusions of glucose or glucose/amino acid solutions. Oral intake was accurately adjusted to account for the calories administered by the intragastric route. Oral intake was also reduced in a calorically equivalent amount to account for the calories received during intravenous glucose. When glucose/amino acid solutions were administered parenterally, adjustments were less accurate, with resultant overeating and weight gain in some monkeys during parenteral nutrition, followed by prolonged suppression of appetite after cessation of the infusions. Further studies of the effects of varied compositions of parenteral nutrition, and varied methods of weaning from infusions, are indicated.