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2. Long-term restoration of the human T-cell compartment after thymectomy during infancy : a role for thymic regeneration?

Author

van Gent, R., Schadenberg, A.W.L., Otto, S.A., Nievelstein, R.A.J., Sieswerda, G.T., Haas, F., Miedema, F., Tesselaar, K., Jansen, N.J.G., and Borghans, J.A.M.

Subjects
CD4-Positive T-Lymphocytes, Male, Interleukin-7, Infant, Newborn, Infant, Thymus Gland, CD8-Positive T-Lymphocytes, Thymectomy, Magnetic Resonance Imaging, Postoperative Complications, Humans, Regeneration, Female, Cardiac Surgical Procedures, Cell Division
Abstract

Thymectomy during early childhood is generally thought to have serious consequences for the establishment of the T-cell compartment. In the present study, we investigated the composition of the T-cell pool in the first 3 decades after thymectomy during infancy due to cardiac surgery. In the first 5 years after thymectomy, naive and total CD4(+) and CD8(+) T-cell numbers in the blood and T-cell receptor excision circle (TREC) levels in CD4(+) T cells were significantly lower than in healthy age-matched controls. In the first years after thymectomy, plasma IL-7 levels were significantly elevated and peripheral T-cell proliferation levels were increased by ∼ 2-fold. From 5 years after thymectomy onward, naive CD4(+) and CD8(+) T-cell counts and TRECs were within the normal range. Because TREC levels are expected to decline continuously in the absence of thymic output, we investigated whether normalization of the naive T-cell pool could be due to regeneration of thymic tissue. In the majority of individuals who had been thymectomized during infancy, thymic tissue could indeed be identified on magnetic resonance imaging scans. Whereas thymectomy has severe effects on the establishment of the naive T-cell compartment during early childhood, our data suggest that functional regrowth of thymic tissue can limit its effects in subsequent years.

Published
2011

4. Quantification of naive and memory T-cell turnover during HIV-1 infection

Author

Vrisekoop, N, Drylewicz, J, van Gent, R., Mugwagwa, T., van Lelyveld, SFL, Veel, E.M., Otto, S.A., Ackermans, M.T., Vermeulen, J.N., Huidekoper, H.H., Prins, J.M., Miedema, F, de Boer, Rob J., Tesselaar, NA, Borghans, JAM, Vrisekoop, N, Drylewicz, J, van Gent, R., Mugwagwa, T., van Lelyveld, SFL, Veel, E.M., Otto, S.A., Ackermans, M.T., Vermeulen, J.N., Huidekoper, H.H., Prins, J.M., Miedema, F, de Boer, Rob J., Tesselaar, NA, and Borghans, JAM

Published
2015

5. Quantification of naive and memory T-cell turnover during HIV-1 infection

Author

Experimentele Afdeling Longziekten, CTI Borghans, Infection & Immunity, MS Infectieziekten, CTI, Directie Raad van Bestuur, Vrisekoop, N, Drylewicz, J, van Gent, R., Mugwagwa, T., van Lelyveld, SFL, Veel, E.M., Otto, S.A., Ackermans, M.T., Vermeulen, J.N., Huidekoper, H.H., Prins, J.M., Miedema, F, de Boer, Rob J., Tesselaar, NA, Borghans, JAM, Experimentele Afdeling Longziekten, CTI Borghans, Infection & Immunity, MS Infectieziekten, CTI, Directie Raad van Bestuur, Vrisekoop, N, Drylewicz, J, van Gent, R., Mugwagwa, T., van Lelyveld, SFL, Veel, E.M., Otto, S.A., Ackermans, M.T., Vermeulen, J.N., Huidekoper, H.H., Prins, J.M., Miedema, F, de Boer, Rob J., Tesselaar, NA, and Borghans, JAM

Published
2015

9. Depletion of naive CD4 T cells by CXCR4-using HIV-1 variants occurs mainly through increased T-cell death and activation

Author

Hazenberg, Mette D., Otto, S.A., Hamann, D., Roos, M.T., Schuitemaker, H., Boer, R.J. de, and Miedema, F.

Subjects
naive T cells, T cell turnover, thymus, CXCR4-using HIV-1variants, Biologie, T cell subsets
Abstract

Using SCID-Hu mice models and in vitro culture systems, it has been shown that syncytium inducing/CXCR4 using (X4) HIV-1 variants affect thymic function through infection and killing of CXCR4 thymocytes. The effect of X4-emergence on naive, memory and effector T-cell subset kinetics in vivo is, however, not known. DESIGN: Prospective cohort study. METHODS: Analysis of changes in naive, memory and effector CD4 and CD8 T-cell numbers and cell division before and after the emergence of X4 variants. RESULTS: Significantly lower numbers of CD4 T cells in patients with X4 variants (n = 18) compared to patients with non-syncytium inducing/CCR5 using variants (n = 74) were due to increased loss of naive and CD27 memory CD4 T cells. In addition, emergence of X4 variants was associated with a small but significant decline in naive CD8 T-cell numbers and increased proportions of dividing CD4 and CD8 naive, memory and effector T cells. CONCLUSION: Loss of naive T cells may suggest thymic dysfunction, however, such an effect would explain only part of the accelerated naive CD4 T-cell decline because of the longevity of naive T cells. Our data suggest that the accelerated naive CD4 T-cell decline induced by X4 variants is caused mainly by increased death and recruitment to the memory compartment of these cells.

Published
2003

10. Early Detection of Ecosystem Regime Shifts: A Multiple Method Evaluation for Management Application

Author

Lindegren, M., Dakos, V., Groger, J.P., Gardmark, A., Kornilovs, G., Otto, S.A., Mollmann, C., Lindegren, M., Dakos, V., Groger, J.P., Gardmark, A., Kornilovs, G., Otto, S.A., and Mollmann, C.

Abstract

Critical transitions between alternative stable states have been shown to occur across an array of complex systems. While our ability to identify abrupt regime shifts in natural ecosystems has improved, detection of potential early-warning signals previous to such shifts is still very limited. Using real monitoring data of a key ecosystem component, we here apply multiple early-warning indicators in order to assess their ability to forewarn a major ecosystem regime shift in the Central Baltic Sea. We show that some indicators and methods can result in clear early-warning signals, while other methods may have limited utility in ecosystem-based management as they show no or weak potential for early-warning. We therefore propose a multiple method approach for early detection of ecosystem regime shifts in monitoring data that may be useful in informing timely management actions in the face of ecosystem change.

Published
2012

11. Maintenance of peripheral naive T cells is sustained by thymus output in mice but not humans.

Author

den Braber, A.J., Mugwagwa, T., Vrisekoop, N., Westera, L., Mögling, R, de Boer, A.B., Willems, N., Schrijver, E.H.R., Spierenburg, G.Th., Gaiser, J.F., Mul, E., Otto, S.A., Ruiter, A.F., Ackermans, M.T., Miedema, F., Borghans, J.A.M., de Boer, R.J., Tesselaar, Kiki, den Braber, A.J., Mugwagwa, T., Vrisekoop, N., Westera, L., Mögling, R, de Boer, A.B., Willems, N., Schrijver, E.H.R., Spierenburg, G.Th., Gaiser, J.F., Mul, E., Otto, S.A., Ruiter, A.F., Ackermans, M.T., Miedema, F., Borghans, J.A.M., de Boer, R.J., and Tesselaar, Kiki

Published
2012

12. Maintenance of peripheral naive T cells is sustained by thymus output in mice but not humans

Author

Infection & Immunity, CTI, Directie Raad van Bestuur, den Braber, A.J., Mugwagwa, T., Vrisekoop, N., Westera, L., Mögling, R, de Boer, A.B., Willems, N., Schrijver, E.H.R., Spierenburg, G.Th., Gaiser, J.F., Mul, E., Otto, S.A., Ruiter, A.F., Ackermans, M.T., Miedema, F., Borghans, J.A.M., de Boer, R.J., Tesselaar, Kiki, Infection & Immunity, CTI, Directie Raad van Bestuur, den Braber, A.J., Mugwagwa, T., Vrisekoop, N., Westera, L., Mögling, R, de Boer, A.B., Willems, N., Schrijver, E.H.R., Spierenburg, G.Th., Gaiser, J.F., Mul, E., Otto, S.A., Ruiter, A.F., Ackermans, M.T., Miedema, F., Borghans, J.A.M., de Boer, R.J., and Tesselaar, Kiki

Published
2012

14. Immune reconstitution in children following chemotherapy for haematological malignancies: a long-term follow-up.

Author

Child Health, Infection & Immunity, Other research (not in main researchprogram), Regenerative Medicine and Stem Cells, Haematologie, Cluster B, CTI, Immunologie/Reumatologie, Infectiezieken, van Tilburg, C.M., van Gent, R., Bierings, M.B., Otto, S.A., Sanders, E.A.M., Nibbelke, E.E., Gaiser, J.F., Janssens-Korpela, P.L., Wolfs, T.F.W., Bloem, A.C., Borghans, J.A.M., Tesselaar, K., Child Health, Infection & Immunity, Other research (not in main researchprogram), Regenerative Medicine and Stem Cells, Haematologie, Cluster B, CTI, Immunologie/Reumatologie, Infectiezieken, van Tilburg, C.M., van Gent, R., Bierings, M.B., Otto, S.A., Sanders, E.A.M., Nibbelke, E.E., Gaiser, J.F., Janssens-Korpela, P.L., Wolfs, T.F.W., Bloem, A.C., Borghans, J.A.M., and Tesselaar, K.

Published
2011

15. Decreased thymic output accounts for decreased naive T cell numbers in children with Down syndrome

Author

Child Health, Circulatory Health, Infection & Immunity, Other research (not in main researchprogram), Cancer, Cluster B, Infectiezieken, Pathologie, CTI, Bloemers, B.L.P., Bont, L.J., de Weger, R.A., Otto, S.A., Borghans, J.A.M., Tesselaar, K., Child Health, Circulatory Health, Infection & Immunity, Other research (not in main researchprogram), Cancer, Cluster B, Infectiezieken, Pathologie, CTI, Bloemers, B.L.P., Bont, L.J., de Weger, R.A., Otto, S.A., Borghans, J.A.M., and Tesselaar, K.

Published
2011

16. Long-term restoration of the human T-cell compartment after thymectomy during infancy: a role for thymic regeneration?

Author

Child Health, Circulatory Health, Infection & Immunity, CTI, Intensive care, Cluster B, Radiologie, Cardiologie, Cardiopulmonale chirurgie, Directie Raad van Bestuur, van Gent, R., Schadenberg, A.W.L., Otto, S.A., Nievelstein, R.A.J., Sieswerda, G.T., Haas, F., Miedema, F., Tesselaar, K., Jansen, N.J.G., Borghans, J.A.M., Child Health, Circulatory Health, Infection & Immunity, CTI, Intensive care, Cluster B, Radiologie, Cardiologie, Cardiopulmonale chirurgie, Directie Raad van Bestuur, van Gent, R., Schadenberg, A.W.L., Otto, S.A., Nievelstein, R.A.J., Sieswerda, G.T., Haas, F., Miedema, F., Tesselaar, K., Jansen, N.J.G., and Borghans, J.A.M.

Published
2011

17. Refined characterization and reference values of the pediatric T- and B-cell compartments

Author

Infection & Immunity, CTI, Haematologie, Cluster B, Infectiezieken, Immunologie/Reumatologie, van Gent, R., van Tilburg, C.M., Nibbelke, E.E., Otto, S.A., Gaiser, J.F., Janssens-Korpela, P.L., Sanders, E.A.M., Borghans, J.A.M., Wulffraat, N.M., Bierings, M.B., Bloem, A.C., Tesselaar, N.A., Infection & Immunity, CTI, Haematologie, Cluster B, Infectiezieken, Immunologie/Reumatologie, van Gent, R., van Tilburg, C.M., Nibbelke, E.E., Otto, S.A., Gaiser, J.F., Janssens-Korpela, P.L., Sanders, E.A.M., Borghans, J.A.M., Wulffraat, N.M., Bierings, M.B., Bloem, A.C., and Tesselaar, N.A.

Published
2009

18. In vivo dynamics of stable chronic lymphocytic leukemia inversely correlate with somatic hypermutation levels and suggest no major leukemic turnover in bone marrow.

Author

van Gent, R., Kater, A.P., Otto, S.A., Jaspers, A., Borghans, J.A.M., Vrisekoop, N., Ackermans, M.A., Ruiter, A.F.C., Wittebol, S., Eldering, E., van Oers, M.H.J., Tesselaar, N.A., Kersten, M.J., Miedema, F., van Gent, R., Kater, A.P., Otto, S.A., Jaspers, A., Borghans, J.A.M., Vrisekoop, N., Ackermans, M.A., Ruiter, A.F.C., Wittebol, S., Eldering, E., van Oers, M.H.J., Tesselaar, N.A., Kersten, M.J., and Miedema, F.

Published
2008

19. Restoration of the CD4 T cell compartment after long-term highly active antiretroviral therapy without phenotypical signs of accelerated immunological aging

Author

Vrisekoop, N., van Gent, R., de Boer, A.B., Otto, S.A., Borleffs, J.C.C., Steingrover, R., Prins, J.M., Kuijpers, T.W., Wolfs, T.F.W., Geelen, S.P.M., Vulto, I., Lansdorp, P., Tesselaar, N.A., Borghans, J.A.M., Miedema, F., Vrisekoop, N., van Gent, R., de Boer, A.B., Otto, S.A., Borleffs, J.C.C., Steingrover, R., Prins, J.M., Kuijpers, T.W., Wolfs, T.F.W., Geelen, S.P.M., Vulto, I., Lansdorp, P., Tesselaar, N.A., Borghans, J.A.M., and Miedema, F.

Published
2008

20. Restoration of the CD4 T cell compartment after long-term highly active antiretroviral therapy without phenotypical signs of accelerated immunological aging

Author

Infection & Immunity, CTI, MS Infectieziekten, Infectiezieken, Vrisekoop, N., van Gent, R., de Boer, A.B., Otto, S.A., Borleffs, J.C.C., Steingrover, R., Prins, J.M., Kuijpers, T.W., Wolfs, T.F.W., Geelen, S.P.M., Vulto, I., Lansdorp, P., Tesselaar, N.A., Borghans, J.A.M., Miedema, F., Infection & Immunity, CTI, MS Infectieziekten, Infectiezieken, Vrisekoop, N., van Gent, R., de Boer, A.B., Otto, S.A., Borleffs, J.C.C., Steingrover, R., Prins, J.M., Kuijpers, T.W., Wolfs, T.F.W., Geelen, S.P.M., Vulto, I., Lansdorp, P., Tesselaar, N.A., Borghans, J.A.M., and Miedema, F.

Published
2008

21. In vivo dynamics of stable chronic lymphocytic leukemia inversely correlate with somatic hypermutation levels and suggest no major leukemic turnover in bone marrow

Author

Infection & Immunity, CTI, van Gent, R., Kater, A.P., Otto, S.A., Jaspers, A., Borghans, J.A.M., Vrisekoop, N., Ackermans, M.A., Ruiter, A.F.C., Wittebol, S., Eldering, E., van Oers, M.H.J., Tesselaar, N.A., Kersten, M.J., Miedema, F., Infection & Immunity, CTI, van Gent, R., Kater, A.P., Otto, S.A., Jaspers, A., Borghans, J.A.M., Vrisekoop, N., Ackermans, M.A., Ruiter, A.F.C., Wittebol, S., Eldering, E., van Oers, M.H.J., Tesselaar, N.A., Kersten, M.J., and Miedema, F.

Published
2008

26. Early determinants of long-term T-cell reconstitution after hematopoietic stem cell transplantation for severe combined immunodefiiency

Author

Borghans, J.A.M., Bredius, R.G., Hazenberg, M.D., Roelofs, H., Jol-van der Zijde, E.C., Heidt, J., Otto, S.A., Kuijpers, T.W., Fibbe, W.E., Vossen, J.M., Miedema, F., Tol, M.J., Borghans, J.A.M., Bredius, R.G., Hazenberg, M.D., Roelofs, H., Jol-van der Zijde, E.C., Heidt, J., Otto, S.A., Kuijpers, T.W., Fibbe, W.E., Vossen, J.M., Miedema, F., and Tol, M.J.

Published
2006

27. Early determinants of long-term T-cell reconstitution after hematopoietic stem cell transplantation for severe combined immunodefiiency

Author

CTI, Borghans, J.A.M., Bredius, R.G., Hazenberg, M.D., Roelofs, H., Jol-van der Zijde, E.C., Heidt, J., Otto, S.A., Kuijpers, T.W., Fibbe, W.E., Vossen, J.M., Miedema, F., Tol, M.J., CTI, Borghans, J.A.M., Bredius, R.G., Hazenberg, M.D., Roelofs, H., Jol-van der Zijde, E.C., Heidt, J., Otto, S.A., Kuijpers, T.W., Fibbe, W.E., Vossen, J.M., Miedema, F., and Tol, M.J.

Published
2006

31. Corrigendum to “Refined characterization and reference values of the pediatric T- and B-cell compartments” [Clin. Immunol. 133 (2009) 95–107]

Author

van Gent, R., primary, van Tilburg, C.M., additional, Nibbelke, E.E., additional, Otto, S.A., additional, Gaiser, J.F., additional, Janssens-Korpela, P.L., additional, Sanders, E.A.M., additional, Borghans, J.A.M., additional, Wulffraat, N.M., additional, Bierings, M.B., additional, Bloem, A.C., additional, and Tesselaar, K., additional

Published
2010
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32. Increased cell division but not thymic dysfunction rapidly affects the T-cell receptor excision circle content of the naive T cell population in HIV-1 infection

Author

Hazenberg, Mette D., Borleffs, J.C.C., Otto, S.A., Cohen Stuart, J.W.T. (James Willem Theodoor), Verschuren, M.C.M. (Martie), Boucher, C.A.B., Coutinho, R.A., Lange, Joep M.A., Rinke de Wit, T.F. (Tobias), Tsegaye, A. (Aster), Dongen, J.J.M. (Jaques) van, Hamann, D. (Dörte), Boer, R.J. de, Miedema, F., Hazenberg, Mette D., Borleffs, J.C.C., Otto, S.A., Cohen Stuart, J.W.T. (James Willem Theodoor), Verschuren, M.C.M. (Martie), Boucher, C.A.B., Coutinho, R.A., Lange, Joep M.A., Rinke de Wit, T.F. (Tobias), Tsegaye, A. (Aster), Dongen, J.J.M. (Jaques) van, Hamann, D. (Dörte), Boer, R.J. de, and Miedema, F.

Published
2000

34. T-cell division in human immunodeficiency virus (HIV)-1 infection is mainly due to immune activation: a longitudinal analysis in patients before and during highly active antiretroviral therapy (HAART)

Author

Hazenberg, Mette D., Cohen Stuart, J.W.T. (James Willem Theodoor), Otto, S.A., Borleffs, J.C.C., Boucher, C.A.B., Boer, R.J. de, Miedema, F., Hamann, D. (Dörte), Hazenberg, Mette D., Cohen Stuart, J.W.T. (James Willem Theodoor), Otto, S.A., Borleffs, J.C.C., Boucher, C.A.B., Boer, R.J. de, Miedema, F., and Hamann, D. (Dörte)

Published
1999

36. Limited CD4 T-cell renewal in early HIV-1 infection : effect of highly active antiretroviral therapy

Author

Fleury, S., Boer, R.J. de, Rizzard, G.J., Wolthers, K.C., Otto, S.A., Welbon, C.C., Graziosi, C., Knabenhans, C., Soudeyns, H., Bart, P.A., Gallant, S., Corpataux, J.M., Gillet, M., Meylan, P., Schnyder, P., Meuwly, J.Y., Spreen, W., Glauser, M.P., Miedema, F., Pantaleo, G., Fleury, S., Boer, R.J. de, Rizzard, G.J., Wolthers, K.C., Otto, S.A., Welbon, C.C., Graziosi, C., Knabenhans, C., Soudeyns, H., Bart, P.A., Gallant, S., Corpataux, J.M., Gillet, M., Meylan, P., Schnyder, P., Meuwly, J.Y., Spreen, W., Glauser, M.P., Miedema, F., and Pantaleo, G.

Published
1998

38. Evidence that human CD8<SUP>+</SUP>CD45RA<SUP>+</SUP>CD27<SUP>-</SUP> cells are induced by antigen and evolve through extensive rounds of division

Author

Hamann, D., Kostense, S., Wolthers, K.C., Otto, S.A., Baars, P.A., Miedema, F., and Lier, R.A.W. van

Abstract

We recently showed that circulating human CD8+ effector cells have a CD45RA+CD27- membrane phenotype. In itself this phenotype appeared to pose a paradox: CD45RA, a marker expressed by unprimed cells, combined with absence of CD27, characteristic for chronically stimulated T cells. To investigate whether differentiation towards the CD45RA+CD27- phenotype is dependent on antigenic stimulation and involves cellular division, TCR Vβ usage and telomeric restriction fragment (TRF) length were analyzed within distinct peripheral blood CD8+ subsets. FACS analysis showed that the TCR Vβ repertoire of CD8+CD45RA+CD27- cells differed significantly from that of unprimed CD8+CD45RA+CD27+ cells. Moreover, in two out of six individuals large expansions of particular Vβ families were observed in the CD8+CD45RA+CD27- subset. CDR3 spectrotyping and single-strand confirmation analysis revealed that within the CD8+CD45RA+CD27- population most of the 22 tested Vβ families were dominated by oligoclonal expansions. The mean TRF length was found to be 2.3 ± 1.0 kb shorter in the CD8+CD45RA+CD27- subset compared with the unprimed CD8+CD45RA+CD27+ population, but did not differ substantially from that of memory type, CD8+CD45RA-CD27+ T cells. These findings indicate that the CD8+CD45RA+CD27- cytotoxic effector population consists of antigen-induced, clonally expanded cells and confirm that the expression of CD45RA is not a strict marker of antigen non-experienced T cells.

Published
1999

39. Dysfunction of Th1 cells and outgrowth of Th2 cells after HIV infection

Author

Meyaard, L., Otto, S.A., Keet, I.P.M., Lier, R.A.W. Van, and Miedema, F.

Subjects
T cells -- Physiological aspects, HIV infection -- Physiological aspects, Cytokines -- Physiological aspects, Cloning -- Research
Abstract

AUTHORS: L. Meyaard 1, S.A. Otto 1, I.P.M. Keet 2, R.A.W. Van Lier 1 and F. Miedema 1. 1Netherlands Red Cross Blood Transfusion Service, Central Laboratory, Amsterdam, Netherlands; and 2Municipal [...]

Published
1994

40. Preferential outgrowth of TH2 cells after HIV infection

Author

Meyaard, L., Otto, S.A., Jong, R. de, and Miedema, F.

Subjects
HIV infection -- Physiological aspects, T cells -- Physiological aspects
Abstract

AUTHORS: L. Meyaard, S.A. Otto, R. de Jong and F. Miedema. Central Laboratory of The Netherlands Red Cross Blood Transfusion Service and the Laboratory of Experimental and Clinical Immunology of [...]

Published
1993

41. Changes in cytokine secretion patterns of CD4+ T-cell clones in human immunodeficiency virus infection

Author

Meyaard, L., Otto, S.A., Keet, I.P.M., Vanlier, R.A.W., and Miedema, F.

Subjects
HIV infection -- Physiological aspects, Cytokines -- Physiological aspects, Cellular immunity -- Research
Abstract

According to the authors' abstract of an article published in Blood, "In addition to the loss of CD4+ T cells in later stages of human immunodeficiency virus (HIV) infection, functional [...]

Published
1995

42. A quantitative framework for selecting and validating food web indicators

Author

Maria Angeles Torres, Thorsten Blenckner, Saskia A. Otto, Martina Kadin, Michele Casini, Otto S.A., Kadin M., Casini M., Torres M.A., and Blenckner T.

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, Indicator-testing framework, Computer science, Performance criteria, Marine strategy framework directive (MSFD), General Decision Sciences, Ecological systems theory, 01 natural sciences, Pelagic fish, Zooplankton, Marine Strategy Framework Directive, Robustness (computer science), Biological sciences, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, Baltic sea, Ecology, business.industry, 010604 marine biology & hydrobiology, Environmental resource management, Data science, Food web, Data availability, Generalized additive modelling (GAM), State space approach, Marine food web indicator, business
Abstract

Finding suitable state indicators is challenging and cumbersome in stochastic and complex ecological systems. Typically, a great focus is given to criteria such as data availability, scientific basis, or measurability. Features associated with the indicator's performance such as sensitivity or robustness are often neglected due to the lack of quantitative validation tools. In this paper, we present a simple but flexible framework for selecting and validating the performance of food web indicators. In specific, we suggest a 7-step process in which indicator performances at a regional scale are quantified and visualized allowing for the selection of complementary indicator suites. We demonstrate its application by comparing the performance of pelagic food web indicators for three basins of the Baltic Sea and by assessing the food web status based on selected indicator suites. Our analysis sheds light on spatial differences in indicator performances with respect to direct and indirect pressures, the role of non-linearity and non-additivity in pressure responses, as well as relationships between indicators caused by species interactions. Moreover, our results suggest that the present food web states in the Bornholm and Gotland basins of the Baltic Sea deviate distinctly from an earlier reference period. We advocate the use of our quantitative framework as decision-support tool for selecting suites of complementary indicators under given management schemes such as the EU Marine Strategy Framework Directive.

Published
2018
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44. Trophic interactions, management trade-offs and climate change: The need for adaptive thresholds to operationalize ecosystem indicators

Author

Kadin M., Blenckner T., Casini M., Gardmark A., Torres M. A., Otto S. A., Kadin M., Blenckner T., Casini M., Gardmark A., Torres M.A., and Otto S.A.

Subjects
Baltic Sea, Coupled generalized additive model, Forage fish, Network, Marine strategy framework directive, Zooplankton
Abstract

Ecosystem-based management (EBM) is commonly applied to achieve sustainable use of marine resources. For EBM, regular ecosystem-wide assessments of changes in environmental or ecological status are essential components, as well as assessments of the effects of management measures. Assessments are typically carried out using indicators. A major challenge for the usage of indicators in EBM is trophic interactions as these may influence indicator responses. Trophic interactions can also shape trade-offs between management targets, because they modify and mediate the effects of pressures on ecosystems. Characterization of such interactions is in turn a challenge when testing the usability of indicators. Climate variability and climate change may also impact indicators directly, as well as indirectly through trophic interactions. Together, these effects may alter interpretation of indicators in assessments and evaluation of management measures. We developed indicator networks - statistical models of coupled indicators - to identify links representing trophic interactions between proposed food-web indicators, under multiple anthropogenic pressures and climate variables, using two basins in the Baltic Sea as a case study. We used the networks to simulate future indicator responses under different fishing, eutrophication and climate change scenarios. Responsiveness to fishing and eutrophication differed between indicators and across basins. Almost all indicators were highly dependent on climatic conditions, and differences in indicator trajectories > 10% were found only in comparisons of future climates. In some cases, effects of nutrient load and climate scenarios counteracted each other, altering how management measures manifested in the indicators. Incorporating climate change, or other regionally non-manageable drivers, is thus necessary for an accurate interpretation of indicators and thereby of EBM measure effects. Quantification of linkages between indicators across trophic levels is similarly a prerequisite for tracking effects propagating through the food web, and, consequently, for indicator interpretation. Developing meaningful indicators under climate change calls for iterative indicator validations, accounting for natural processes such as trophic interactions and for trade-offs between management objectives, to enable learning as well as setting target levels or thresholds triggering actions in an adaptive manner. Such flexible strategies make a set of indicators operational over the long-term and facilitate success of EBM.

Published
2019

45. Contribution to the symposium: 'sustainable use of baltic sea resources' original article a three-dimensional view on biodiversity changes: Spatial, temporal, and functional perspectives on fish communities in the baltic sea

Author

Frelat R., Orio A., Casini M., Lehmann A., Merigot B., Otto S. A., Sguotti C., Mollmann C., Frelat R., Orio A., Casini M., Lehmann A., Merigot B., Otto S.A., Sguotti C., and Möllmann C.

Subjects
Functional trait, Baltic Sea, Demersal fish community, Spatio-temporal dynamic, Multivariate analysi, Species distribution
Abstract

Fisheries and marine ecosystem-based management requires a holistic understanding of the dynamics of fish communities and their responses to changes in environmental conditions. Environmental conditions can simultaneously shape the spatial distribution and the temporal dynamics of a population, which together can trigger changes in the functional structure of communities. Here, we developed a comprehensive framework based on complementary multivariate statistical methodologies to simultaneously investigate the effects of environmental conditions on the spatial, temporal and functional dynamics of species assemblages. The framework is tested using survey data collected during more than 4000 fisheries hauls over the Baltic Sea between 2001 and 2016. The approach revealed the Baltic fish community to be structured into three sub-assemblages along a strong and temporally stable salinity gradient decreasing from West to the East. Additionally, we highlight a mismatch between species and functional richness associated with a lower functional redundancy in the Baltic Proper compared with other sub-areas, suggesting an ecosystem more susceptible to external pressures. Based on a large dataset of community data analysed in an innovative and comprehensive way, we could disentangle the effects of environmental changes on the structure of biotic communities-key information for the management and conservation of ecosystems. VC International Council for the Exploration of the Sea 2018.

Published
2018

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