Community dynamics and development of soft bottom macrozoobenthos in the German Bight (North Sea) 1969 - 2000 Dynamik und Entwicklung makrozoobenthischer Weichbodengemeinschaften in der Deutschen Bucht (Nordsee) 1969 - 2000 Alexander Schroeder Ber. Polarforsch. Meeresforsch. 494 (2005) ISSN 1618 - 3193 Alexander Schroeder Alfred-Wegener-Institut füPolar- und Meeresforschung Postfach 12 01 61 D - 27568 Bremerhaven Die vorliegende Arbeit ist die inhaltlich unverändert Fassung einer Dissertation, die in der Sektion Vergleichende Okosystemforschung bei Prof. Dr. W. E. Arntz angefertigt und 2003 dem Fachbereich 2 (BiologieIChemie) der UniversitäBremen vorgelegt wurde. 'Sie ist übedie Staats- und Universitätsbibliothe Bremen als pdf-Dokument erhältlic unter: http://elib.suub,uni-bremen.de/dissertafions/ Contents Zusammenfassung .............................................................................................................. IV Summary .................................................................................................................................. VI 1 . Introduction ...................................................................................................................... 1 2 . The German Bight (North Sea) ................................................................................. 4 2.1 Topography .......................................................................................................4 2.2 Climate ............................................................................................................... 4 2.3 Hydrography ......................................................................................................5 2.4 Sediments ..........................................................................................................6 2.5 Benthic fauna ....................................................................................................7 3 . Methods ........................................................................................................................... 10 3.1 Long term Stations ..........................................................................................10 3.2 Benthos data ...................................................................................................11 3.2.1 Sampling methodology ................................................................................... 11 3.2.2 Sample processing .........................................................................................12 3.2.3 Data sources ..................................................................................................13 3.2.4 Data quality control .........................................................................................13 3.2.5 Data selection for the long-term study ............................................................14 3.2.6 Spatial sampling ............................................................................................. 15 3.3 Environmental data .........................................................................................16 3.4 Analytical methods .........................................................................................16 3.4.1 Indices ............................................................................................................16 3.4.1. 1 Spatial distribution & variability ..................................................................17 3.4.1 .2 Diversity ..................................................................................................... 18 3.4.1.3 Multivariate similarity .................................................................................. 21 Multivariate analytical procedures .................................................................. 22 MDS ...........................................................................................................22 Cluster Analysis ......................................................................................... 23 Statistical tests ...............................................................................................23 Comparison of univariate measures ..........................................................23 Correlations ................................................................................................24 Smoothing of time series............................................................................ 24 Multivariate differences ..............................................................................24 Comparing multivariate pattern between stations ......................................25 Multivariate Mantel correlograms ...............................................................25 Multiple statistical fest ................................................................................26 3.4.4 Analysis of spatial variability ...........................................................................26 3.4.5 Samples size dependence .............................................................................27 3.4.6 Temporal community development ................................................................ 28 3.4.7 Environmental influences ...............................................................................29 4 . Results ............................................................................................................................. 30 4.1 Precision of sampling position ......................................................................30 4.2 Spatial variability .............................................................................................31 4.2.1 Spatial structuring ........................................................................................... 31 4.2.1. 1 Gradienfs.................................................................................................... 32 4.2.1.1.1 Community cornposition ....................................................................................32 4.2.1.1.2 Surn pararneter ..................................................................................................33 4.2.2 Benthic community composition .....................................................................34 4.2.2.1 SSd ............................................................................................................34 4.2.2.2 WB .............................................................................................................35 4.2.2.3 SIf ...............................................................................................................37 4.2.2.4 FSd............................................................................................................. 38 4.2.3 Precision of quantitative sum parameters ......................................................39 4.2.3.1 Sample size influence on densify ...............................................................40 4.2.3.2 Sample size influence on biomass .............................................................41 4.2.4 Community structure and sample size influences ..........................................42 4.2.4.1 Sample size influence on species number ................................................. 43 4.2.4.2 Sample size infiuence on evenness ........................................................... 47 4.2.4.3 Sample size influence on heferogeneify diversify ...................................... 48 4.2.5 Multivariate community similarity .................................................................... 49 4.2.5.2 Sample size influence on mulfivariafe similarify .........................................51 4.2.6 Temporal changes in spatial variability .......................................................... 52 4.3 Methodological changes ................................................................................54 4.3.1 Penetration depth & grab type ........................................................................54 4.3.2 Combination of different grabs .......................................................................55 43.21 Univariate measures .................................................................................. 55 4.3.2.2 Inter-sample similarify ................................................................................ 57 4.3.3 Sampling time .................................................................................................58 4.4 Benthos time series ........................................................................................59 Similarity between benthic communities ........................................................59 Similarity of temporal development ................................................................ 60 Community development at single stations .................................................... 61 SSd ............................................................................................................61 WB .............................................................................................................70 SIt ...............................................................................................................78 FSd............................................................................................................. 85 Temporal aufocorrelation ........................................................................... 92 4.5 Abiotic environmental time series .................................................................93