Preliminary Validation of a Short Form of the Perceived Stress Questionnaire for Use in Clinical Rehabilitation Counseling Research and Practice

Background

The purpose of this study was to develop and validate a short form of the Perceived Stress Questionnaire (PSQ) in people with spinal cord injury (SCI).

Methods

The sample consisted of 274 individuals with SCI. Measures administered were the PSQ-20, Center for Epidemiological Studies-Depression Scale, and Rand Short-Form 36 General Health Scale.

Results

Results showed that after selecting two items from each subscale of the PSQ-20, factor analysis results supported a unidimensional measure for the PSQ-8. The PSQ-8 total score demonstrated a high correlation with the PSQ-20 total score. The reliability of the PSQ-8 was adequate and similar to the PSQ-20. The PSQ-8 measurement correlated well with the external correlates of depression and health status. The mediation analysis indicated depression as a partial mediator for the relationship between perceived stress and health status, indicating people with higher levels of perceived stress had poorer health outcome in this study.

Conclusions

This study provides evidence to support the psychometric properties of PSQ-8 in people with SCI. The PSQ-8 is a brief, reliable, unidimensional, and psychometrically sound measure of perceived stress that can be used in clinical rehabilitation and mental health counseling research and practice.

Prevalence rates of arthritis among US older adults with varying degrees of depression: Findings from the 2011 to 2014 National Health and Nutrition Examination Survey

OBJECTIVE

Arthritis and depressive symptoms often interact and negatively influence one another to worsen mental and physical health outcomes. Better characterization of arthritis rates among older adults with different levels of depressive symptoms is an important step toward informing mental health professionals of the need to detect and respond to arthritis and related mental health complications. The primary objective is to determine arthritis rates among US older adults with varying degrees of depression.

METHODS

Using National Health and Nutrition Examination Survey 2011 to 2014 data (N = 4792), we first identified participants aged ≥50 years. Measures screened for depressive symptoms and self-reported doctor-diagnosed arthritis. Weighted logistic regression models were conducted.

RESULTS

Prevalence of arthritis was 55.0%, 62.9%, and 67.8% in participants with minor, moderate, and severe depression, respectively. In both unadjusted and adjusted regression models, a significant association between moderate depression and arthritis persisted. There were also significant associations between minor and severe depression with arthritis.

CONCLUSIONS

Arthritis is commonly reported in participants with varying degrees of depression. This study highlights the importance of screening for and treating arthritis-related pain in older adults with depressive symptoms and the need for future geriatric psychiatry research on developing integrated biopsychosocial interventions for these common conditions.

Differences in Self-Reported Physical Activity, Exercise Self-Efficacy and Outcome Expectancies, and Health Status by Body Mass Index Groups in People with Chronic Pain

The study purpose was to determine how self-reported lifestyle physical activity levels, exercise self-efficacy and outcome expectancies, and health status differ by body mass index for persons with chronic pain. From U.S. clinics and community networks, 209 adults reporting chronic musculoskeletal pain were recruited for the cross-sectional survey. Data were analyzed using analysis of variance. Participants with self-described obesity reported the lowest physical activity, reduced exercise self-efficacy and positive outcome expectancies, and poorer health status. Promoting graded activity while addressing motivational factors from health behavior theory for people with chronic pain and obesity should be encouraged in rehabilitation programs.

Personal and environmental contextual factors as mediators between functional disability and quality of life in adults with serious mental illness: a cross-sectional analysis

PURPOSE

To examine personal and environmental contextual factors as mediators of functional disability on quality of life (QOL) in a sample of individuals with serious mental illness (SMI).

METHODS

A cross-sectional analysis of 194 individuals with SMI (major depressive disorder = 38.1%; bipolar disorder = 35.6%; schizophrenia spectrum disorder = 25.8%) recruited from four psychosocial rehabilitation clubhouses was undertaken to test a multiple regression model assuming that personal (i.e., resilience, social competence, and disability acceptance) contextual factors and environmental (i.e., family support, support from friends, and support from significant others) contextual factors would mediate the relationship of functional disability on QOL. The bootstrap test for multiple mediators was then used to test for the significance of the indirect effects functional disability on QOL through the mediators.

RESULTS

In the simple regression model, functional disability had a strong relationship with QOL; however, after introducing the potential mediators, its effect was significantly reduced indicating partial mediation effects. The final regression model yielded a large effect, accounting for 44% of the variance in QOL. Controlling for all other potential mediating factors, social competence, disability acceptance, family support, and support from friends were found to partially mediate the relationship between functional disability and QOL. Bias-corrected bootstrap procedure results further supported the mediation model.

CONCLUSIONS

The findings from the study provide good support for the inclusion of person-environment contextual factors in conceptualizing the relationship between functional disability and QOL for individuals with SMI.

Towards an integration of the health promotion models of self-determination theory and theory of planned behavior among people with chronic pain

PURPOSE

People with chronic pain and related disability often report motivational difficulties with engaging in health-promoting behaviors. Although health promotion models of self-determination theory (SDT) and theory of planned behavior (TPB) have been shown to explain the motivational processes behind health behaviors in the general population, there is limited theoretical research among persons with chronic pain. This study examined the integration of such theories relevant to physical activity and exercise behavior among pain populations.

RESEARCH METHOD

Secondary data analyses were conducted using cross-sectional surveys from 198 participants with chronic musculoskeletal pain recruited from U.S. clinics and community networks. The primary outcome was self-reported physical activity and exercise participation. Predictor variables included pain intensity, functional disability, and SDT and TPB measures. Hierarchical regression analysis was conducted to examine the associations between these variables.

RESULTS

Findings demonstrated that in the first step, functional disability was associated with physical activity and exercise; and in the second step, all SDT factors were associated with physical activity and exercise. In the final step of the model, only certain SDT and TPB factors were associated with physical activity and exercise.

CONCLUSIONS

Despite preexisting pain and functional disability, the findings suggest that health behavior factors from both SDT and TPB are associated with physical activity and exercise participation. This line of research should encourage rehabilitation professionals to recommend regular physical activity and exercise, while simultaneously addressing and monitoring the SDT and TPB factors that are well-timed and appropriate for persons with chronic pain through motivation-oriented rehabilitation approaches. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Sociodemographic characteristics, health conditions, and functional impairment among older adults with serious mental illness reporting moderate-to-severe pain

OBJECTIVE

To compare adults aged ≥50 years with serious mental illness reporting moderate-to-severe pain to older adults with serious mental illness without pain with respect to sociodemographic characteristics, health conditions, and functional impairment.

METHOD

Secondary data analyses were conducted using baseline assessments of 183 participants recruited for the Helping Older People Experience Success (HOPES) study from three community mental health centers. The primary outcome was self-reported, nonexperimentally induced, moderate-to-severe pain (referent = no-to-mild pain). Predictor variables consisted of sociodemographic characteristics, health conditions, and functional impairment. We conducted univariable and multivariable logistic regression analyses to examine the associations between these variables.

RESULTS

Sixty-one participants (33.3%) from our sample reported pain. Pain was associated with all of the sociodemographic and health-related factors in univariable analyses. In the multivariable model, only older age, pain-related activity interference, and physical and emotional health-related social limitations were significantly associated with pain.

CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

The presence of moderate-to-severe pain in older adults with serious mental illness is associated with pain-attributable impairment of activities and social problems above and beyond the substantial functional limitations routinely experienced by this high-risk, high-need group. Given the high rates of preexisting conditions and persistent social impairment among these older adults, our findings suggest that pain may contribute to worse overall functional outcomes. Future research and clinical interventions focused on improving outcomes should include an evaluation of pain as a contributor to decreased functioning and assess the need for early intervention, nonpharmacological pain management, or other health promotion services in psychiatric rehabilitation. (PsycINFO Database Record

Validation of the Behavioural Regulation in Exercise Questionnaire-2 for adults with chronic musculoskeletal pain

BACKGROUND/AIMS

The Behavioural Regulation in Exercise Questionnaire-2 (BREQ-2) has demonstrated reliability and validity in the general population; yet the psychometric properties have not been tested among rehabilitation populations, such as persons experiencing chronic musculoskeletal pain. The objective of the current study was to examine the factorial structure and psychometric properties of the BREQ-2 in a sample of adults with chronic musculoskeletal pain.

METHODS

Adults with chronic musculoskeletal pain (n=211) were recruited from clinical and community networks in the United States. Data were collected using a cross-sectional online survey and analysed using confirmatory factor analysis, multiple indicators multiple causes analysis, and correlational techniques. Participants completed the BREQ-2 and other measures relevant to self-determination theory, including outcome expectancies, self-efficacy and family and friend support for physical activity and exercise.

FINDINGS

Results indicated the intercorrelated model fit the data well. The five factors of amotivation, external regulation, introjected regulation, identified regulation and intrinsic regulation toward physical activity and exercise demonstrated good reliability and construct validity.

CONCLUSIONS

This study provides evidence of factorial and construct validity for the BREQ-2 among people with chronic musculoskeletal pain. Implications for rehabilitation practitioners and researchers are discussed.

Characteristics of Medicaid recipients in Methadone Maintenance Treatment: A comparison across the lifespan

Methadone Maintenance Treatment (MMT) is utilized by an increasingly broad age-range of individuals with opioid use disorders. The present study aims to (1) describe health, behavioral, and psychosocial characteristics among adults aged 50 years and older compared with younger adults enrolled in MMT, (2) describe socioeconomic and clinical characteristics by age and time in MMT and (3) investigate whether age influences the associations between duration of MMT and health and psychosocial characteristics. Our sample consisted of 1364 recipients from four MMT programs (age ranged from 18 to 77 years; mean: 38 years: standard deviation: 11.1 years) in Southern New England Using descriptive analysis and logistic regression, we determined that one-third (33%) of adults 50 years of age and older had been admitted or readmitted into MMT within the previous 6 months, 27% had been in treatment for 7-47 months, while 40% had been in treatment for at least 4 years. Psychosocial problems and smoking were both common (>80%) at the time of MMT enrollment but declined with longer duration of MMT for all age groups. The prevalence of metabolic conditions was associated with increased duration of MMT for younger adults for both age (1.03; CI 1.02-1.05; p < 0.001) and time in treatment (1.29; 1.12-1.44; p < 0.001; interaction term 0.0996; CI 0.993-0.998). Tailored strategies to enhance engagement, retention, and prevention among MMT recipients should include considerations of age, health status upon enrollment, duration of treatment, and developmental context.

Feasibility, Acceptability, and Preliminary Effectiveness of a Peer-Delivered and Technology Supported Self-Management Intervention for Older Adults with Serious Mental Illness

To assess the feasibility, acceptability, and preliminary effectiveness of a peer-delivered and technology supported integrated medical and psychiatric self-management intervention for older adults with serious mental illness. Ten older adults with serious mental illness (i.e., schizophrenia, schizoaffective disorder, bipolar disorder, or major depressive disorder) and medical comorbidity (i.e., cardiovascular disease, obesity, diabetes, chronic obstructive pulmonary disease, hypertension, and/or high cholesterol) aged 60 years and older received the PeerTECH intervention in their homes. Three certified peer specialists were trained to deliver PeerTECH. Data were collected at baseline, one-month, and three-month. The pilot study demonstrated that a three-month, peer-delivered and technology-supported integrated medical and psychiatric self-management intervention ("PeerTECH") was experienced by peer specialists and participants as feasible and acceptable. PeerTECH was associated with statistically significant improvements in psychiatric self-management. In addition, pre/post, non-statistically significant improvements were observed in self-efficacy for managing chronic health conditions, hope, quality of life, medical self-management skills, and empowerment. This pre/post pilot study demonstrated it is possible to train peers to use technology to deliver an integrated psychiatric and medical self-management intervention in a home-based setting to older adults with serious mental illness with fidelity. These findings provide preliminary evidence that a peer-delivered and technology-supported intervention designed to improve medical and psychiatric self-management is feasible, acceptable, and is potentially associated with improvements in psychiatric self-management, self-efficacy for managing chronic health conditions, hope, quality of life, medical self-management skills, and empowerment with older adults with serious mental illness and chronic health conditions.

Perceived Mindfulness and Depressive Symptoms Among People with Chronic Pain

The study purpose was to evaluate pain catastrophizing and psychological distress as mediators for the relationship between perceived mindfulness and depressive symptoms in people with chronic pain. We conducted an online cross-sectional survey with 211 adults with chronic musculoskeletal pain recruited from U.S. clinics and community networks. A serial multiple mediation analysis was performed using ordinary least-squares regressions and a bootstrap testing approach. Pain catastrophizing and psychological distress, independently and jointly, mediated the relationship between mindfulness and depressive symptoms. Rehabilitation counseling professionals should consider targeting mindfulness, pain catastrophizing, and psychological distress in psychosocial treatment for people with chronic pain.

Perinatal substance use, residential instability, and negative behavioral outcomes among adolescents: Lessons from the maternal lifestyle study

PROBLEM

Both housing instability and prenatal substance use are known risk factors for behavioral problems among adolescents.

METHODS

The purpose of this study was to investigate the association between residential instability (residential mobility and homelessness) and delinquent behaviors among adolescents enrolled in the maternal lifestyle study (MLS), a 16-year research study that explored short-term and long-term effects of in-utero exposure to cocaine and/or opiates (N = 736). Logistic regression was used to measure the association between housing problems with youth crimes, school delinquency, and substance use at 11, 15, and 16 years of age.

FINDINGS

Both high-frequency residential mobility and homelessness were associated with deviant behaviors across the entire sample of children born with in-utero cocaine/opiate exposure and those without.

CONCLUSIONS

Psychiatric nursing care of youth should include a comprehensive assessment of residential instability to identify risk and target potential interventions.

Depression and Handgrip Strength Among U.S. Adults Aged 60 Years and Older from NHANES 2011-2014

OBJECTIVES

Sarcopenia is a gradual loss of muscle mass and strength that occurs with aging. This muscle deterioration is linked to increased morbidity, disability, and other adverse outcomes. Although reduced handgrip strength can be considered a marker of sarcopenia and other aging-related decline in the elderly, there is limited research on this physical health problem in at-risk groups with common biopsychosocial conditions such as depression. Our primary objective was to ascertain level of combined handgrip strength and its relationship with depression among adults aged 60 years and older.

DESIGN

Unadjusted and adjusted linear regression models were conducted with a cross-sectional survey dataset.

SETTING

Secondary dataset from the 2011-2014 National Health and Nutrition Examination Survey (NHANES).

PARTICIPANTS

Community-dwelling, non-institutionalized adults ≥60 years old (n=3,421).

MEASUREMENTS

The predictor variables included a positive screen for clinically relevant depression (referent=PHQ-9 score <10). The criterion variable of combined handgrip strength (kg) was determined using a dynamometer.

RESULTS

Mean age and BMI were 69.9 years (51.5% female) and 28.8 kg/m2, respectively. Mean combined handgrip strength in the overall cohort was 73.5 and 46.6 kg in males and females, respectively. Three hundred thirty-six (9.8%) reported symptoms of depression. In unadjusted and fully adjusted models, depression was significantly associated with reduced handgrip strength (B = -0.26±0.79 and B = -0.19±0.08, respectively; p<0.001).

CONCLUSION

Our findings demonstrate handgrip strength has a significant inverse association with depression. Future longitudinal studies should investigate the causal processes and potential moderators and mediators of the relationships between depression and reduced handgrip strength. This information may further encourage the use of depression and handgrip strength assessments and aid in the monitoring and implementation of health care services that address both physical and mental health limitations among older adult populations.

Smoking Predicting Physical Activity in an Aging America

OBJECTIVES

Tobacco smoking and physical inactivity are among leading behavioral risk factors for ill health in older adults. This study considers how smoking is associated with physical activity.

DESIGN

Using a Life-Course model, data are analyzed regarding this relationship, controlling for, and interacted with, life-course and other factors. Daily smokers and sometimes smokers were hypothesized to engage in less leisure-time physical activity than those who never smoked, while those who stopped smoking were expected to do more than never smokers. Analyses were performed using SAS-Callable SUDAAN.

SETTING AND PARTICIPANTS

Secondary data from ten years of a national sample of adults aged 18 and over of the National Health Interview Survey, 2001-2010, are used (N = 264,945, missing data excluded, of 282,313 total cases).

MEASUREMENTS

Daily smokers, occasional smokers, and smoking quitters are compared to never smokers with regard to requisite physical activity (150 minutes per week of moderate, 100 of vigorous, and/or 50 of strengthening activity). Life-course measures include birth cohorts, age, and year of survey, as well as gender, race/ethnicity, and education.

RESULTS

Overall, hypotheses are supported regarding daily smokers and quitters; but the hypothesis is strongly rejected among sometimes smokers, who are much more likely to do requisite physical activity. Findings differ by age, sometimes smokers age 65 and over being less likely to do physical activity. Findings among all men are similar to the overall findings, while those among all women are similar to those for older respondents. Associations of smoking status with physical activity vary greatly by race/ethnicity.

CONCLUSIONS

Daily smokers may be most in need of both smoking cessation and leisure-time physical activity interventions. Smoking-cessation efforts may pay greater physical activity benefits among women and the aged, while smoking-reduction efforts may provide better outcomes among men. Smoking reduction efforts may pay more exercise benefits among African-Americans and Hispanics.

Mindfulness as a protective factor against depressive symptoms in people with fibromyalgia

Background: Depressive symptoms complicate pain management for people with FM, with adverse consequences such as a greater need for pain medications and limited pain coping strategies. Determining risks and protective factors associated with depressive symptoms in persons with FM could inform the development and implementation of mental health interventions.Aims: To formulate and test a behavioral activation model of depression with mindfulness as a protective factor for people with FM.Methods: We conducted an online cross-sectional survey with 117 adults with FM from community and clinic networks. Path analysis was used to assess the relationships of pain intensity, perceived stress, activity interference, pain catastrophizing and mindfulness with depressive symptoms.Results: Mindfulness has a negative direct association with depressive symptoms and a negative indirect association with depressive symptoms through perceived stress, activity interference and pain catastrophizing. Perceived stress, activity interference and pain catastrophizing had direct associations with depressive symptoms. Finally, perceived stress, activity interference and pain catastrophizing had indirect associations with depressive symptoms through pain intensity.Conclusions: Mindfulness seems to play an important role as a protective factor against the negative effects of stress and depression among people with FM and should be included in mental health interventions for chronic pain.

Own and partner pain intensity in older couples: longitudinal effects on depressive symptoms

Chronic pain has been linked to depression among individuals and their partners. Yet, little is known about long-term mutual influences between pain intensity and depressive symptoms within couples as they age. Using a nationally representative U.S. sample of wives and husbands aged 50 and older (mean = 64.53, SD = 7.86), this study explored the links between own and partner pain intensity and depressive symptoms across an 8-year period. A total of 963 heterosexual married couples drawn from the Health and Retirement Study completed interviews biennially from 2006 to 2014. Dyadic growth curve models examined mutual associations within couples and controlled for sociodemographic characteristics, length of marriage, and marital quality, along with self-rated health, number of chronic health conditions, and functional disability. For wives and husbands, their own greater baseline pain intensity was significantly linked to their own higher levels of depressive symptoms. Unexpectedly, wives with greater baseline pain intensity reported decreases in their depressive symptoms over time. There were also partner effects such that husbands' greater pain intensity at baseline was associated with increases in wives' depressive symptoms over time. Findings highlight the importance of considering both individual and spousal associations between pain intensity and depressive symptoms in later life. Understanding how individual and couple processes unfold may yield critical insights for the development of intervention and prevention efforts to maintain mental health among older chronic pain patients and their spouses.

Preliminary Validation of a Short-Form Version of the Attachment Style Questionnaire for Use in Clinical Rehabilitation Counseling Research and Practice

The purpose of this study was to develop and validate a short-form version of the Attachment Style Questionnaire (ASQ) in people with disabilities. The construction sample consisted of 108 participants recruited from spinal cord injury (SCI) advocacy organizations. The cross-validation sample comprised 140 individuals with traumatic injuries recruited from a rehabilitation hospital. Measures administered were the ASQ, Trait Hope Scale, Sense of Coherence Scale, and Satisfaction With Life Scale. Results showed that the three subscales of secure, anxious, and avoidant attachment from the short-form ASQ had high correlations with the three subscales from the long-form ASQ. The reliability of the subscales for the short-form ASQ was adequate and similar to the long-form ASQ. Both the short- and long-form ASQ subscales were found to correlate with hope, sense of coherence, and subjective well-being in the expected theoretical directions. Confirmatory factor analysis also supported the three-factor measurement structure of the short-form ASQ. This study provides evidence to support the psychometric properties of the abbreviated ASQ in people with disabilities. The short-form version of the ASQ is a brief, reliable, and psychometrically sound measure of attachment that can be used in clinical rehabilitation counseling research and practice.

Relationships between self-determination theory and theory of planned behavior applied to physical activity and exercise behavior in chronic pain

This study examined the relationships between self-determination theory (SDT) and theory of planned behavior (TpB) applied to physical activity and exercise behavior (PA&E) in people with chronic pain. Two hundred and eleven adults with chronic musculoskeletal pain (28 males and 183 females, age range 18 to 82 years, mean age 43 years) were recruited from online support groups and clinic networks in the United States. Participants completed SDT measures relevant to PA&E on perceived autonomy support, autonomy, competence, and relatedness, as well as TpB measures relevant to PA&E on intention, attitudes, subjective norms, and perceived behavioral control. Correlational techniques and canonical correlation analysis were performed to examine the relationships and variance within and between theoretical dimensions. Overall, the SDT set accounted for 37% of the TpB variance and the TpB set accounted for 32% of the SDT set variance. The results indicate there are statistical similarities and differences between concepts in SDT and TpB models for PA&E. Using both empirical guidance and clinical expertise, researchers and practitioners should attempt to select and integrate non-redundant and complementary components from SDT, TpB, and other related health behavior theories.

Cell-specific and developmental expression of lectican-cleaving proteases in mouse hippocampus and neocortex

Mounting evidence has demonstrated that a specialized extracellular matrix exists in the mammalian brain and that this glycoprotein-rich matrix contributes to many aspects of brain development and function. The most prominent supramolecular assemblies of these extracellular matrix glycoproteins are perineuronal nets, specialized lattice-like structures that surround the cell bodies and proximal neurites of select classes of interneurons. Perineuronal nets are composed of lecticans, a family of chondroitin sulfate proteoglycans that includes aggrecan, brevican, neurocan, and versican. These lattice-like structures emerge late in postnatal brain development, coinciding with the ending of critical periods of brain development. Despite our knowledge of the presence of lecticans in perineuronal nets and their importance in regulating synaptic plasticity, we know little about the development or distribution of the extracellular proteases that are responsible for their cleavage and turnover. A subset of a large family of extracellular proteases (called a disintegrin and metalloproteinase with thrombospondin motifs [ADAMTS]) is responsible for endogenously cleaving lecticans. We therefore explored the expression pattern of two aggrecan-degrading ADAMTS family members, ADAMTS15 and ADAMTS4, in the hippocampus and neocortex. Here, we show that both lectican-degrading metalloproteases are present in these brain regions and that each exhibits a distinct temporal and spatial expression pattern. Adamts15 mRNA is expressed exclusively by parvalbumin-expressing interneurons during synaptogenesis, whereas Adamts4 mRNA is exclusively generated by telencephalic oligodendrocytes during myelination. Thus, ADAMTS15 and ADAMTS4 not only exhibit unique cellular expression patterns but their developmental upregulation by these cell types coincides with critical aspects of neural development.

A methanotrophic marine molluscan (bivalvia, mytilidae) symbiosis: mussels fueled by gas

An undescribed mussel (family Mytilidae), which lives in the vicinity of hydrocarbon seeps in the Gulf of Mexico, consumes methane (the principal component of natural gas) at a high rate. The methane consumption is limited to the gills of these animals and is apparently due to the abundant intracellular bacteria found there. This demonstrates a methane-based symbiosis between an animal and intracellular bacteria. Methane consumption is dependent on the availability of oxygen and is inhibited by acetylene. The consumption of methane by these mussels is associated with a dramatic increase in oxygen consumption and carbon dioxide production. As the methane consumption of the bivalve can exceed its carbon dioxide production, the symbiosis may be able to entirely satisfy its carbon needs from methane uptake. The very light (delta(13)C = -51 to -57 per mil) stable carbon isotope ratios found in this animal support methane (delta(13)C = -45 per mil at this site) as the primary carbon source for both the mussels and their symbionts.

Deep-sea hydrocarbon seep communities: evidence for energy and nutritional carbon sources

Mussels, clams, and tube worms collected in the vicinity of hydrocarbon seeps on the Louisiana slope contain mostly "dead" carbon, indicating that dietary carbon is largely derived from seeping oil and gas. Enzyme assays, elemental sulfur analysis, and carbon dioxide fixation studies demonstrate that vestimentiferan tube worms and three clam species contain intracellular, autotrophic sulfur bacterial symbionts. Carbon isotopic ratios of 246 individual animal tissues were used to differentiate heterotrophic (8(13)C = -14 to -20 per mil), sulfur-based (8(13)C = -30 to -42 per mil), and methane-based (8(13)C = <-40 per mil) energy sources. Mussels with symbiotic methanotrophic bacteria reflect the carbon isotopic composition of the methane source. Isotopically light nitrogen and sulfur confirm the chemoautotrophic nature of the seep animals. Sulfur-based chemosynthetic animals contain isotopically light sulfur, whereas methane-based symbiotic mussels more closely reflect the heavier oceanic sulfate pool. The nitrogen requirement of some seep animals may be supported by nitrogen-fixing bacteria. Some grazing neogastropods have isotopic values characteristic of chemosynthetic animals, suggesting the transfer of carbon into the background deep-sea fauna.

Thermogenic gas hydrates in the gulf of Mexico

Thermogenic gas hydrates were recovered from the upper few meters of bottom sediments in the northwestern Gulf of Mexico. The hydrates were associated with oil-stained cores at a water depth of 530 meters. The hydrates apparently occur sporadically in seismic "wipeout" zones of sediments in a region of the Gulf continental slope at least several hundred square kilometers in area.