02424nas a2200229   4500008004100000245007300041210006900114260006600183300001200249490000800261520164200269653001401911653001701925653001801942653001401960653002201974653002601996100002302022700002202045700002002067856010702087       2007                        eng d00aThree-dimensional spatial structure: nematodes in a sandy tidal flat0 aThreedimensional spatial structure nematodes in a sandy tidal fl  aNORDBUNTE 23, D-21385 OLDENDORF LUHE, GERMANYbINTER-RESEARCH  a177-1860 v3363 aBenthic infauna live in a three-dimensional world, and patterns of horizontal distribution may vary with depth in the sediment, as may the mechanisms that determine those patterns. This study examines how horizontal spatial structure varies with depth in a semi-exposed coarse-sand flat adjacent to St Martin's, one of the Isles of Scilly, UK. Nematode samples were collected from 3 sediment depth horizons (0 to 5, 5 to 10 and 10 to 15 cm) in a nested hierarchical design, with samples 0.1, 1 and 10 m apart. Results show that spatial patterns are strongest amongst samples of intermediate depth (5 to 11) cm), and generally insignificant amongst samples collected from 10 to 15 cm. There is short-order spatial autocorrelation in surface (0 to 5 cm) samples, with samples collected 10 cm apart being significantly more alike than samples collected further apart. We postulate that this is because spatial structure of nematodes in surface sediments is determined by patchiness induced by interactions between the water column and the physical structure of the surface layers of the sediment, which are constantly reworked by wind and tides. The deeper layers, 10 to 15 cm below the surface, are constantly reworked by a dense population of heart urchins Echinocardium cordatum. It is only in the intermediate horizon that relatively stable conditions allow nematode assemblages to establish spatial structure over a range of scales. It is concluded that the interaction between sediment permeability, and therefore interfacial advection, and bioturbation in controlling infaunal diversity and spatial patterns is potentially important.10aadvection10abioturbation10aEchinocardium10anematodes10aspatial structure10avertical distribution1 aSomerfield, P., J.1 aDashfield, S., L.1 aWarwick, R., M.  uhttps://nematoda.myspecies.info/content/three-dimensional-spatial-structure-nematodes-sandy-tidal-flat02634nas a2200301   4500008004100000245010100041210006900142260006600211300001000277490000800287520163000295653001701925653001901942653001501961653001401976653001801990653002402008100001902032700002202051700002002073700002002093700001602113700001502129700001602144700001902160700001802179856013502197       2009                        eng d00aEffects of CO2 induced seawater acidification on infaunal diversity and sediment nutrient fluxes0 aEffects of CO2 induced seawater acidification on infaunal divers  aNORDBUNTE 23, D-21385 OLDENDORF LUHE, GERMANYbINTER-RESEARCH  a59-750 v3793 aA mesocosm experiment was conducted to quantify the effects of short- (2 wk) and long-term (20 wk) exposure to acidified seawater on the structure and diversity of macrofaunal and nematode assemblages in 2 different sediment. types. The impact of acidified seawater on sediment nutrient fluxes was also determined. Using carbon dioxide (CO2) gas, seawater was acidified to pH 7.3 (mimicking ocean acidification), 6.5 or 5.6 (mimicking leakage from a sub-seabed CO2 store site). Control treatments were maintained in natural seawater [pH approximate to 8.0). Exposure to acidified seawater significantly altered community structure and reduced diversity for both macrofaunal and nematode assemblages, However, the impact on nematodes was less severe than that on macrofauna. While the communities in both sediment types were significantly affected by changes in seawater pH, impacts on sandy sediment fauna were greater than those on muddy sediment fauna. Sandy sediments also showed the greatest effects with respect to nutrient fluxes. In sand, the efflux of nitrite, nitrate and silicate decreased in response to increased acidification while the efflux of ammonium increased, In mud, acidification increased the efflux of ammonium but had no effect on the other nutrients. We conclude that both leakage from carbon storage and ocean acidification could cause significant changes in the structure and diversity of coastal sediment communities. Lowered seawater pH could also affect nutrient cycling directly by altering bacterial communities and indirectly through impacts on the abundance and activity of key bioturbators.10aBiodiversity10aCarbon storage10aMacrofauna10ameiofauna10aNutrient flux10aOcean acidification1 aWiddicombe, S.1 aDashfield, S., L.1 aMcNeill, C., L.1 aNeedham, H., R.1 aBeesley, A.1 aMcEvoy, A.1 aOxnevad, S.1 aClarke, K., R.1 aBerge, J., A.  uhttps://nematoda.myspecies.info/content/effects-co2-induced-seawater-acidification-infaunal-diversity-and-sediment-nutrient-fluxes