| 1. |
- Bjorling, Patrik, et al.
(author)
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Ten Year Follow-up After Total Wrist Arthroplasty
- 2017
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Conference paper (peer-reviewed)abstract
- Hypothesis Total wrist arthroplasty (TWA) is an option in the management of wrist arthritis. The aim of the study was to evaluate the long-term results of TWA.Methods In this cohort study, we followed 56 cases that underwent TWA (Avanta, Biax, Universal 2 and Maestro) between 2005 and 2006 at a single-center. Data was collected preoperatively and 10 years postoperatively. Patient-related outcome measures, grip strength, range of motion (ROM), VAS pain scores were analyzed.Results VAS pain scores and patient-related measures were significantly improved at the 10-year follow-up. Jamar grip strength was also significantly improved. ROM remained largely unchanged, except for extension which improved significantly at the 10-year follow-up. Five of 56 TWAs were revised. Five patients died of unrelated causes and 10 were lost to follow-up.Summary Points This study shows good long-term results after TWA with a high level of patient satisfaction. The revision rate was acceptable.
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| 2. |
- Fischer, Per, 1981-, et al.
(author)
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Functional and kinematic analysis of a wrist radial hemiarthroplasty design
- 2017
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Conference paper (peer-reviewed)abstract
- Hypothesis A radial hemiarthroplasty could obviate difficulties related to distal component loosening of the total wrist arthroplasty. The aim of this study is to investigate kinematically, the feasibility of a new design for radial wrist hemiarthroplasty.Methods Six, fresh-frozen cadaveric wrist specimens were used. Testing was performed on the native wrist, after insertion of a radial hemi-arthroplasty with intact proximal carpal row (Hemi) and with proximal row carpectomy (Hemi+PRC). Each wrist was fixed to an experimental table with the tendons of the extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), extensor carpi ulnaris (ECU), flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), and abductor pollicis longus (APL) attached to the apparatus. Range of motion, axis of rotation, and muscle moment arms were recorded in manually controlled movements in wrist flexion/extension, radial/ulnar deviation, dart throwers motion, and circumduction.Results A statistically significant decrease in flexion range of motion occurred between the intact and Hemi conditions and between the intact and Hemi+PRC conditions with no significant differences in flexion range of motion occurring between the Hemi and Hemi+PRC conditions. No statistically significant changes in range of motion occurred in extension, radial deviation, ulnar deviation, flexion/ulnar deviation component of the dart throw, extension/radial deviation component of the dart throw, or circumduction functional tests.Summary Points This study indicates that the new wrist radial hemiarthroplasty can produce a stable wrist with range of motion similar to the native wrist. Overall, wrist kinematics appears to be equally acceptable in hemiarthroplasty with and without resection of the proximal row.
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| 3. |
- Fischer, Per, 1981-
(author)
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Hemi and total wrist arthroplasty
- 2019
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Doctoral thesis (other academic/artistic)abstract
- Aim: To study implant survival and implant loosening following primary total wrist arthroplasty (TWA) using four different implants. To report outcome following wrist revision arthroplasty. To evaluate a new radial wrist hemi arthroplasty (RWHA) design clinically and biomechanically.Method: The studies included 136 primary TWAs and 16 revision TWAs, both studies with prospectively collected data. Six fresh frozen cadaveric wrist specimen were used for biomechanical analysis. The RHWA was evaluated clinically in a pilot series of 20 cases.Results: Total implant survival was 92% but with high frequency of implant loosening of surviving Re-Motion implants. None of the surviving Maestro implants were considered radiographically loose. Implant survival following revision arthroplasty was 75%, considerably lower than following primary TWAs. However, none of the patients with surviving revision implants had pain at rest and little or no pain in activity. The surgical procedure and placement of the RHWA was feasible. Overall, the kinematic and functional changes appeared acceptable compared to the native wrist. None of the patients underwent revision following RHWA but reoperation was performed in 7 patients on the indication of persistent pain. However, patients reported relief of pain and improvement of patient-reported outcome measures.Conclusion: High long-term implant survival and no signs of radiographic loosening was found for the Maestro implant. However, the Maestro implant is no longer available on the market and we believe there is a need for new TWA designs. Revision arthroplasty is a valid option in the management of failed TWA. However, implant survival is lower than for primary TWAs and as many as 25% require additional surgery. Promising results were found using the new RHWA design but the implant needs modification before further testing.
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| 4. |
- Fischer, Per, 1981-, et al.
(author)
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Revision Arthroplasty of the Wrist in Patients With Rheumatoid Arthritis, Mean Follow-Up 6.6 Years
- 2018
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In: Journal of Hand Surgery-American Volume. - : Elsevier. - 0363-5023 .- 1531-6564. ; 43:5, s. 489.e1-489.e7
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Journal article (peer-reviewed)abstract
- PURPOSE: Management of failed total wrist arthroplasty (TWA) can be challenging; surgical treatment options include salvage arthrodesis, revision arthroplasty, and resection arthroplasty. There are few studies regarding salvage arthrodesis, and revision arthroplasty has been infrequently investigated. The aim of the study was to report the outcome after revision arthroplasty of the wrist.METHODS: A retrospective cohort of 16 revision TWAs was evaluated between 2003 and 2016. Data were collected before surgery and 1 and 5 years after surgery. The indication for revision arthroplasty was failed TWA. The primary end point was implant survival. Secondary outcome measures included visual analog scale (VAS) pain scores, range of motion, handgrip strength, and functional scoring with the Canadian Occupational Performance Measure (COPM), Patient-Rated Wrist Evaluation (PRWE), and Disabilities of the Arm, Shoulder, and Hand (DASH).RESULTS: Mean follow-up was 6.6 years. Synthetic bone graft was used in 9 cases, allograft corticocancellous bone graft in 1 case, and cement in 6 cases. Of the 16 revision TWAs, 4 were re-revised, 1 because of infection, and 3 cases underwent total wrist arthrodesis. In the non-re-revised cases, range of motion and grip strength was preserved compared with preoperative results. The VAS pain score in activity improved, but not significantly, at 1 (median, 1; range, 0-4.5) and 5 years after surgery (median, 0) compared with before surgery (median, 5). The COPM performance and satisfaction as well as PRWE scores improved significantly at 1 year (median COPM performance, 4.8; COPM satisfaction, 5.6; and PRWE, 24) and improved, but not significantly, at the 5-year follow (median COPM performance, 4.8; COPM satisfaction, 5.0; and PRWE, 37) in the non-re-revised cases.CONCLUSIONS: Revision arthroplasty of the wrist is a valid motion-preserving option to wrist arthrodesis in the management of failed TWA. However, the outcome is uncertain and as many as 25% require additional surgery.TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.
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| 5. |
- Hooke, Alexander W., et al.
(author)
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An anatomic and kinematic analysis of a new total wrist arthroplasty design
- 2015
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In: Journal of wrist surgery. - New York : Thieme Medical Publishers. - 2163-3916 .- 2163-3924. ; 4:2, s. 121-127
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Journal article (other academic/artistic)abstract
- Background: Total wrist arthroplasty (TWA) is a viable surgical treatment for disabling wrist arthritis. While current designs are a notable improvement from prior generations, radiographic loosening and failures remain a concern.Purpose: The purpose of this investigation is to evaluate a new total wrist arthroplasty design kinematically. The kinematic function of a native, intact cadaveric wrist was compared with that of the same wrist following TWA.Method: Six, fresh-frozen wrist cadaveric specimens were utilized. Each wrist was fixed to an experimental table and its range of motion, axis of rotation, and muscle moment arms were calculated. The following tendons were attached to the apparatus to drive motion: extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), extensor carpi ulnaris (ECU), flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), and abductor pollicis longus (APL). The wrist was then manually moved along a guide by an experimenter through a series of motions including flexion-extension, radial-ulnar deviation, and circumduction. The experiment was then performed on the specimen following implantation of the TWA.Results: Following the TWA procedure, there were statistically significant decreases in the ulnar deviation and the flexion/ulnar deviation component of dart throw ranges of motion. There were no statistically significant changes in flexion, extension, radial deviation, the extension/radial deviation component of the dart thrower motion, or the circumduction range of motion.Conclusions: Kinematic analysis of the new TWA suggests that a stable, functional wrist is achievable with this design.Clinical Relevance: While appreciating the limitations of a cadaveric study, this investigation indicates that the TWA design studied merits study in human populations.
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| 6. |
- Niklasson, Johan, et al.
(author)
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Pulp-to-palm distance is associated with functional outcome 3 months after combined plating for distal radius fracture
- 2019
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In: Abstract book IFSHT. - Freiburg : Intercongress GmbH. - 9783000635854
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Conference paper (peer-reviewed)abstract
- Clinical issue/s: Objective: The Distal Radius Fracture (DRF) is the most common fracture in adults. After surgical management, extensive rehabilitation programs are common in order to restore function. Some patients are not able to fully move their fingers during the first month after a DRF-surgery (Pulp-to-palm distance=PTP).Clinical reasoning: The purpose of this study was to investigate if increased PTP 4 weeks after DRF surgery is associated with an inferior functional outcome 3 months postoperatively after DRF-surgery.innovative, analytical or new approach: Materials and Methods: This prospective study involved 53 DRF-patients with intra-articular type C fractures according to the AO-classification. All patients were treated with combined volar and dorsal plating. The patients were assessed at 4 weeks and 3 months postoperatively according to PTP-distance, wrist range of motion, grip strength, VAS pain scores and self-assessed hand function. Rehabilitation was the same for all patients with focus on self-training instructions, regardless of individual finger and wrist status.Results: 20 patients had a PTP > 0 cm 4 weeks after surgery. Three months after surgery, all patients had regained full fingermotion. The group with PTP > 0 cm showed significantly inferior range of motion regarding dorsal- and volar flexion, radial- and ulnar deviation as well as grip strength and quick-DASH 3 months after surgery. Inferior outcomes for pro- and supination and PRWE-scores was seen but were not significant. Pain at rest and during activity showed no significant differences between the groups.Contribution to advancing HT practice: Conclusions: Impaired finger motion 4 weeks postoperatively is a significant predictor of functional outcome 3 months postoperatively in surgically treated DRFs. Measuring the PTP-distance can assist the physiotherapist in the allocation of rehabilitation resources.
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| 7. |
- Pettersson, Kurt, et al.
(author)
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Pyrolytic Carbon Hemiarthroplasty in the Management of Proximal Interphalangeal Joint Arthritis
- 2015
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In: Journal of Hand Surgery-American Volume. - : Elsevier BV. - 0363-5023 .- 1531-6564. ; 40:3, s. 462-468
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Journal article (peer-reviewed)abstract
- Purpose To review clinical, subjective, and radiographic results of pyrocarbon hemiarthroplasty for proximal interphalangeal (PIP) joint arthritis. Methods A total of 42 fingers in 38 patients underwent PIP joint hemiarthroplasty between 2005 and 2011. Preoperative diagnoses included 28 with osteoarthritis or posttraumatic arthritis and 10 with inflammatory arthritis. Average age at the time of surgery was 56 years. Digits treated included: index (10), middle (20), ring (9), and little (3). Average follow-up was 4.6 years (minimum, 2 y). Results There was considerable improvement in patient satisfaction measures including Canadian Occupational Performance Measure for both performance and satisfaction and Disabilities of the Arm, Shoulder, and Hand and visual analog scale pain scores. There was no significant change in motion or grip and pinch strength after surgery. Four joints were revised for failure: 3 underwent arthrodesis and 1 was converted to a silicone PIP joint arthroplasty. Radiographic outcomes in surviving implants demonstrated a Sweets and Stern grade 0 in 37 implants and grade 3 in 1. Conclusions Pyrocarbon hemiarthroplasty appears to be a viable alternative to total joint arthroplasty in the treatment of PIP joint arthritis. Clinical and patient satisfaction outcomes compared favorably with published outcomes of arthroplasty. Radiographic outcomes of PIP joint hemiarthroplasty were encouraging with respect to implant position and loosening. Compared with total joint arthroplasty, proximal hemiarthroplasty is a simple procedure that preserves more bone stock and would allow for better success of salvage options such as arthrodesis and revision arthroplasty. Copyright (C) 2015 by the American Society for Surgery of the Hand. All rights reserved.
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| 8. |
- Sagerfors, Marcus, 1977-, et al.
(author)
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Combined Volar T-Plate and Dorsal Pi-Plate for Distal Radius Fractures : A Consecutive Series of 80 AO type C2 and C3 Cases
- 2019
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In: Journal of wrist surgery. - : Thieme Medical Publishers. - 2163-3916 .- 2163-3924. ; 8:3, s. 180-185
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Journal article (peer-reviewed)abstract
- Background The distal radius fracture (DRF) is the most common fracture among adults. In recent years, there has been a shift toward volar locking plates in the treatment of DRFs, and this shift has taken place with a low degree of evidence.Question/purposes Can combined volar T-plating and dorsal pi-plating of AO type C fractures yield a good functional and radiographic outcome 1 year postoperatively?Patients and Methods In a retrospective cohort study, we evaluated 102 consecutive patients operated with combined dorsal and volar plating, of whom 80 completed the 1-year follow-up. The DRFs were operated between 2012 and 2013. All cases were AO type C2 and C3 fractures. The primary outcome was functional scoring including radiographic examination. Secondary outcome measures included range of motion, visual analog scale (VAS) pain scores, and hand grip strength.Results The median Batra radiographic score was 84.5. Wrist extension was 74% of the uninjured side, flexion was 70%, pronation was 94%, and supination was 90%. The Patient-Rated Wrist Evaluation score was 21 points, and the Disabilities of the Arm, Shoulder, and Hand score was 19.4 points. VAS pain scores were 0 at rest and 3 during activity. Hand grip strength was 80% of the uninjured side. Radiographic outcome did not correspond to a patient-reported outcome. Hardware removal was performed in 15/80 cases.Conclusions We conclude that a good outcome can be expected after combined dorsal and volar plating of DRFs. Radiographic outcome is not necessarily associated with functional outcome 1 year postoperatively. The rate of hardware removal was acceptable.
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| 9. |
- Sagerfors, Marcus, MD, PhD, 1977-, et al.
(author)
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Patient-Perceived Outcome After Total Wrist Arthroplasty : A Single-Center Study of 223 Cases
- 2016
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In: Hand. - : Sage Publications. - 1558-9447 .- 1558-9455. ; 11:1_suppl, s. 2S-2S
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Journal article (peer-reviewed)abstract
- Purpose: Total wrist arthroplasty (TWA) is an established surgical treatment for wrist arthritis. The aim of the investigation is to report patient-perceived outcome measures after TWA operated at a single referral center in Sweden.Methods: In a cohort study with prospective collection of data, we evaluated 193 consecutive patients with a TWA (223 wrists) preoperatively, 1 and 5 years postoperatively. The wrists were implanted between 2002 and 2014. Outcome measures studied were range of motion (ROM), visual analogue scale (VAS) pain scores, hand grip strength, and patient-related outcome measures. Secondary outcome measures included implant survivorship, which was estimated using the Kaplan-Meier method, and radiographic loosening 5 years postoperatively.Results: VAS pain scores and patient-related outcome measures improved significantly for all TWAs. Improved hand grip strength was noted for all TWAs except Universal 2. ROM improved somewhat, especially for the Biax and Maestro TWAs. Cumulative implant survival after 5 years was 99% for Remotion, 95% for Maestro, and 84% for Biax. Radiographic loosening was present in 26% of the Biax cases, 18% of the Remotion cases, and 2% of the Maestro cases.Conclusions: All TWA designs in this study offer a high level of patient satisfaction. The design of the implant may affect patient-perceived outcome 5 years postoperatively. Good mid to long-term results can be achieved in patients undergoing TWA.
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| 10. |
- Sagerfors, Marcus, 1977-, et al.
(author)
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Patient related functional outcome after total wrist arthroplasty : a single center study of 206 cases
- 2015
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In: Hand Surgery. - Singapore : World Scientific Publishing. - 0218-8104. ; 20:1
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Journal article (peer-reviewed)abstract
- Objectives: To prospectively evaluate patient related outcome measures after total wrist arthroplasty (TWA) using four different total wrist implants operated at a single referral center in Sweden.Methods: 206 primary TWAs were assessed preoperatively and after one year postoperatively with respect to the following eight outcome measures: Range of motion (flexion/extension, radial/ulnar deviation, pronation/supination), hand grip strength, Canadian Occupational Performance Measure (COPM), performance and satisfaction, Visual Analog Scale (VAS) pain scores at rest and in activity.Results: The Maestro TWA had a significantly greater improvement of radial/ulnar deviation than the Biax and Remotion TWAs. COPM performance and satisfaction improved more for the Maestro and Universal 2 prostheses than the Biax and Remotion.Conclusions All four TWAs offer reduced VAS-scores and improved COPM-scores with preserved hand grip strength and somewhat improved range of motion. The Maestro TWA performed favorably compared to the Remotion TWA. Implant design may affect patient related outcome.
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| 11. |
- Sagerfors, Marcus, 1977-, et al.
(author)
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Total Wrist Arthroplasty : A Single-Center Study of 219 Cases With 5-Year Follow-up
- 2015
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In: Journal of Hand Surgery-American Volume. - : Saunders Elsevier. - 0363-5023 .- 1531-6564. ; 40:12, s. 2380-2387
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Journal article (peer-reviewed)abstract
- Purpose: To assess implant survival and radiographic loosening after total wrist arthroplasty (TWA) operated at a single tertiary referral center in Sweden.Methods: In a prospective cohort study, we evaluated 189 consecutive patients with a TWA(219 wrists). The wrists were implanted between 2002 and 2013. The primary end point was revision for any reason. The mean follow-up period was 7 years (range, 2-13 years). In addition, radiological examination was done for evidence of prosthetic loosening 5 years postoperatively. Implant survival was estimated using the Kaplan-Meier method. Secondary outcome measures included range of motion, visual analog scale pain scores, hand grip strength, and patient-related outcome measures.Results: Cumulative implant survival after 8 years was 81% for Biax, 94% for Remotion, and 95% for Maestro implants. Radiographic loosening was present in 26% of wrists with the Biax design, 18% of those with Remotion, and 2% of those with Maestro. Visual analog scale pain scores and patient-related outcome scores improved significantly for all TWAs. Improved hand grip strength was noted for all TWAs except for the Universal 2. Range of motion improved somewhat, especially for the Biax and Maestro TWAs.Conclusions: Good midterm to long-term results were achieved in patients undergoing TWA. Radiographic loosening did not necessarily correlate with implant survival rates, but rather to severe arthritic destruction of the wrist preoperatively. All TWA implants studied offered a high level of patient satisfaction.
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| 12. |
- Sagerfors, Marcus, 1977-
(author)
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Total wrist arthroplasty : A clinical, radiographic and biomechanical investigation
- 2016
-
Doctoral thesis (other academic/artistic)abstract
- Aim: To study patient-related functional outcome measures, implant survival and radiographic loosening after total wrist arthroplasty (TWA) using four different implants. To evaluate a new TWA design biomechanically and clinically.Methods: The studies included two cohort studies with prospectively collected data (n=206 and n=219), an anatomic and kinematic analysis in a cadaveric model and a pilot study (n=20).Results: The Maestro TWA had a significantly greater improvement of radial/ulnar deviation than the Biax and Remotion TWAs. Summarized patientrelated functional outcome was significantly better for the Maestro than for the Remotion TWA. Cumulative implant survival after 8 years was 94% for Remotion, and 95% for Maestro implants. Radiographic loosening five years postoperatively was present in 26% of the Biax wrists, 18% of those with Remotion, and 2% of those with Maestro. Following TWA with the new implant design in a cadaveric model, there were no statistically significant changes compared to a native wrist regarding flexion, extension, radial deviation, the extension/radial deviation component of the dart-thrower’s motion, or the circumduction range of motion. Clinically, there was significant improvement of COPM, PRWE and VAS pain scores. Wrist extension and ulnar deviation improved, while grip strength remained largely unchanged.Conclusions: TWA is a surgical procedure which may offer a high level of patient satisfaction. Implant design may affect patient-related functional outcome after TWA. Implant survival as well as the frequency of radiographic loosening differed considerably between the four types of implants and might be a result of different implant design. Kinematic analysis of the new TWA design suggests that a stable and functional wrist is achievable with this design. Surgical placement of the new total wrist implant was reproducible and the implant yielded good patient-related outcome measures in the short term. Since TWA is an evolving procedure, further studies are warranted in order to refine indications and the place for TWA in modern hand surgery.
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| 13. |
- Singh, B. P., et al.
(author)
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Experimental access to Transition Distribution Amplitudes with the PANDA experiment at FAIR
- 2015
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In: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 51:8
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Journal article (peer-reviewed)abstract
- Baryon-to-meson Transition Distribution Amplitudes (TDAs) encoding valuable new information on hadron structure appear as building blocks in the collinear factorized description for several types of hard exclusive reactions. In this paper, we address the possibility of accessing nucleon-to-pion (pi N) TDAs from (p) over barp -> e(+)e(-)pi(0) reaction with the future PANDA detector at the FAIR facility. At high center-of-mass energy and high invariant mass squared of the lepton pair q(2), the amplitude of the signal channel (p) over barp -> e(+)e(-)pi(0) admits a QCD factorized description in terms of pi N TDAs and nucleon Distribution Amplitudes (DAs) in the forward aid backward kinematic regimes. Assuming the validity of this factorized description, we perform feasibility studies for measuring (p) over barp -> e(+)e(-)pi(0) with the PANDA detector. Detailed simulations on signal reconstruction efficiency as well as on rejection of the most severe background channel, i.e. (p) over barp -> pi(+)pi(-)pi(0) were performed for the center-of-mass energy squared s = 5 GeV2 and s = 10 GeV2, in the kinematic regions 3.0 < q(2) < 4.3 GeV2 and 5 < q(2) < 9 GeV2, respectively, with a neutral pion scattered in the forward or backward cone vertical bar cos theta(pi 0)vertical bar > 0.5 in the proton-antiproton center-of-mass frame. Results of the simulation show that the particle identification capabilities of the PANDA detector will allow to achieve a background rejection factor of 5 . 10(7) (1 . 10(7)) at low (high) q(2) for s = 5 GeV2, and of 1 . 10(8) (6 . 10(6)) at low (high) q(2) for s = 10 GeV2, while keeping the signal reconstruction efficiency at around 40%. At both energies, a clean lepton signal can be reconstructed with the expected statistics corresponding to 2 of integrated luminosity. The cross sections obtained from the simulations are used to show that a test of QCD collinear factorization can be done at the lowest order by measuring scaling laws and angular distributions. The future measurement of the signal channel cross section with PANDA will provide a new test of the perturbative QCD description of a novel class of hard exclusive reactions and will open the possibility of experimentally accessing pi N TDAs.
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| 14. |
- Yang, Yang, et al.
(author)
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Effects of winter severity on spring phytoplankton development in a temperate lake (Lake Erken, Sweden)
- 2016
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In: Hydrobiologia. - : Springer Science and Business Media LLC. - 0018-8158 .- 1573-5117. ; 780:1, s. 47-57
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Journal article (peer-reviewed)abstract
- Phytoplankton seasonal succession has been linked to a variety of serial environmental changes, especially weather- and climate-induced physical forcing. This study compared spring phytoplankton dynamics after winters of different severity (cold, normal, and warm) in Lake Erken, Sweden. The spring diatom bloom was dominated by different functional groups: group A (centric diatoms 5-10 mu m) after cold winters, B (centric diatoms > 15 mu m) after normal winters, and P (Aulacoseira granulata, Fragilaria crotonensis) after warm winters. Our results suggest that weather-related processes were the primary external drivers accounting for differences in spring phytoplankton dynamics in Lake Erken. Spring phytoplankton are influenced by overwintering species from the last autumn that can initiate the following spring bloom. Average taxonomic distinctness of the spring community was assessed using a new biodiversity measurement that incorporates taxonomic relatedness information. This value was lower than expected after warm and cold winters, which had winter air temperature 1A degrees C deviation from an average value calculated over 21 years. Such winters increased the level of disturbance or stress to the lake, resulting in a spring with less diverse phytoplankton by narrowing the niche for species with various ecological requirements.
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| 15. |
- Yang, Yang, 1985-
(author)
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Phytoplankton and Physical Disturbance : Seasonal dynamics in temperate Lake Erken, Sweden
- 2015
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Doctoral thesis (other academic/artistic)abstract
- Phytoplankton mirrors changes in the environment and plays an important role in biogeochemical processes. Phytoplankton dynamics is the outcome of both autogenic succession and external disturbances. This thesis focused on the seasonal variation of water column stability and its effects on phytoplankton, particularly considering the influence of mixing events on phytoplankton development. Lake Erken is a dimictic lake with weak and often interrupted summer stratification, which represents an intermediate case between a polymictic lake and a lake with strong summer stratification.There are two diatom phases annually. The spring bloom is caused by pioneer centric diatoms, and the autumn diatom phase is dominated by meroplanktonic diatoms induced by turnover. A summer Cyanobacteria bloom – mainly Gloeotrichia echinulata, depended on the length and stability of stratification.Winter and spring air temperature is found to play an important role in the annual succession of phytoplankton by initiating changes in ice/snow-cover and lake thermal stability and setting the basic status. Instead of starting from zero, the vernal phytoplankton piles up on the overwintering community, this trans-annual ecological memory influences both the composition and diversity and taxonomic distinctness of spring phytoplankton.Water column stability during summer in Lake Erken is mainly influenced by wind-induced turbulence and internal seiches. As thermal stratification develops from early until late summer, variations in stability and gradual deepening of the thermocline depth influence phytoplankton dynamics directly by changing its distribution, and also indirectly by altering the nutrient and light availability. A new disturbance index (DI) was defined to quantify environmental stability/disturbance and tested well to indicate phytoplankton equilibrium status in two summer stratification periods. The concept of species and functional groups was generally used in this study. However, a next generation sequencing based approach was also tested and proved to provide an excellent candidate for revealing distribution patterns of phytoplankton in inland waters.
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| 16. |
- Yang, Yang, 1985-, et al.
(author)
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Repetitive baselines of phytoplankton succession in an unstably stratified temperate lake (Lake Erken, Sweden) : a long-term analysis
- 2016
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In: Hydrobiologia. - : Springer Science and Business Media LLC. - 0018-8158 .- 1573-5117. ; 764:1, s. 211-227
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Journal article (peer-reviewed)abstract
- The seasonal development of phytoplankton is a sequence of consecutive events with waxes and wanes of biomass and compositional shifts. This study analyzed 16 years data in Lake Erken, Sweden and revealed four baselines of phytoplankton succession with their underlying drivers. Results showed that there were two diatom-dominated phases annually. The vernal community was dominated by centric diatoms larger than 15 A mu m (functional groups B and C) which were fast-growing diatoms being highly efficient in the use of nutrients. The autumn community was comprised mainly meroplanktonic mixing-dependent Aulacoseira granulata and Fragilaria sp. (MP and P) or/and large centric diatoms (B). Between the two mixing-phases with diatoms, a Gloeotrichia echinulata (H 2) bloom occurred due to its preference for a stratified water column with elevated water temperatures and high light availability. The summer stratification in Lake Erken was weak and short, thus, favoring meroplanktonic diatoms to peak once the lake turned over in early autumn. Lake Erken represents an intermediate case between a highly mixed polymictic lake and a lake with strong summer stratification, where the observed stratification patterns allowed the development of an autumn diatom phase similar, by extent, to the vernal one and mainly dominated by meroplanktonic diatoms.
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| 17. |
- Yang, Yang, 1985-, et al.
(author)
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Water column stability and summer phytoplankton dynamics in a temperate lake (Lake Erken, Sweden)
- 2016
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In: Inland Waters. - 2044-2041 .- 2044-205X. ; 6:4, s. 499-508
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Journal article (peer-reviewed)abstract
- Phytoplankton development in aquatic ecosystems is caused by interactions among multiple environmental factors. Physical processes, particularly development of thermal stratification, have been proposed to be important factors for regulating phytoplankton composition and abundance during summer. This study examined the temporal pattern of thermal stratification during summer in Lake Erken, Sweden, based on 21 years of historical data spanning 23 years and investigated the role played by water stability on phytoplankton development. Water column stability indexes were calculated from high frequency measurements during periods of summer thermal stratification. Clustering and ordination analyzed the dissimilarities between communities during different periods and extracted the significant environmental gradients controlling phytoplankton succession. Wind introduced the major external disturbance to Lake Erken during summer and played an important role for the progression of thermocline depth. Species-specific thermal stability preference or tolerance determined the response of individual species to the stratification and constitutes a mechanism of species selection in phytoplankton dynamics. Lake Erken is an unstably stratified lake during summer, caused by wind-induced turbulence and internal seiches. Adaptation to these unstable conditions is the major determinant of phytoplankton dynamics. Hydrodynamic variability, characterized by different stability indexes in early, mid, and late summer, was the key factor regulating phytoplankton dynamics, directly by changing phytoplankton distribution and indirectly by altering both the light and nutrient availability in the epilimnion.
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