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The significance of distance along the beach-dune transect and different moisture conditions as regards the decay of Zostera marina leaf litter was investigated in simple field experiments in three temperate, medium- to fine-quartz-sediment, sandy beaches of the Gulf of Gdańsk in Poland. 1800 replicate litterbags of freshly stranded Zostera marina leaves were placed in beach sediments at different strata and levels on each of the beaches. The litterbags were sampled after 5, 10, 50, 100 and 150 days in the field and the remaining material was then dried and weighed. Under similar conditions of sediment composition, salinity and wave inundation, ANOVA tests revealed significant differences in breakdown through time and site. Thus there were some differences in the decay process between the low and high beach. In the former, degradation proceeded rapidly in the initial stages and then stabilised, while in the latter it remained linear throughout the study period.Matter loss in each stratum was also seasonally dependent. This may, however, be more closely linked to successional changes in the chemistry and/or microflora of the beach wrack than to its physical breakdown. Differences between organic matter degradation in the high and low beaches may be explained by differences in the moisture regime and nutrient status, and not by differences in the decay processes themselves. Therefore, two decay centres were found in the beach-dune system: the low beach together with the strandline (wrack consumption 12–21 % day−1 in the warm season, and 4–10 % day−1 in the cold season) and the dune (active consumption 2–6 % day−1 in the warm season only).
This paper evaluates the second part of a three-year field study to investigate the effects of the beach macro- and meiofauna community structure on the decay of stranded wrack on Hel Beach (see Jędrzejczak 2002),f ocusing on successional changes and the colonisation of wrack by beach fauna. The investigation enabled the associated faunal assemblages to be characterised. Zostera marina tissue was colonised by the supralittoral fauna in two distinct phases. The macrofauna, including the talitrid amphipod Talitrus saltator,ad ult Diptera and Coleoptera, colonised the wrack within a day,with maximum numbers being recorded after 3 days. Thereafter,their numbers in the samples declined and the meiofauna, consisting of nematodes, oligochaetes,tur bellarians and dipteran larvae, became increasingly abundant. After 18 days,the wrack surface was dominated by meiofauna. This faunal succession was not directly related to the degradation of the seagrass tissue,whic h proceeded linearly throughout the study period. Exclusion of macrofauna from the wrack by the use of < 1 mm mesh litterbags had no appreciable effect on the rate of dry matter loss. Therefore,the major macrofaunal wrack consumers,including T. saltator and Coleoptera,d id not affect the rate of seagrass disintegration. The effect of meiofaunal nematodes, oligochaetes,gast rotrichs and turbellarians on wrack breakdown could not be accurately determined. However,the development of the meiofaunal community suggested that changes in the fauna community were linked more closely to successional changes in the chemistry and/or microflora of the beach wrack than to its physical breakdown.
The effects of the beach community structure of macro- and meiofauna on the process of beach wrack decay were investigated by means of a simple field colonisation experiment in a temperate, fine quartz sediment, sandy beach at the end of the Hel Peninsula in Poland. 1260 replicate litterbags of three mesh sizes (12 mm, 0.5 mm, 48 μm) containing fresh wrack were used to assess the role of faunal and non-faunal components in the breakdown of stranded Zostera marina. Wrack breakdown was determined during a three-year field study. This paper presents the first part of the results of this field experiment, which refer to the effects of fragmentation detritivory, leaching and decay rates. Material was lost from the bags at a rapid rate, with only 22–32% of the original dry mass remaining after 27 days in the field. This degradation was not directly related to the faunal succession of the eelgrass tissue, which proceeded in two distinct phases throughout the study period. Exclusion of macrofauna from the wrack by the use of finer-mesh litterbags (< 1 mm) had no appreciable effect on the rate of dry matter loss. Microbial decay, and abiotic leaching and fragmentation are probably the major causes of seagrass weight loss from the litterbags.
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