 |
| Titel |
The effects of clam fishing on the properties of surface sediments in the lagoon of Venice, Italy |
| VerfasserIn |
R. J. Aspen, S. Vardy, R. G. Perkins, I. R. Davidson, R. Bates, D. M. Paterson |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1027-5606
|
| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 8, no. 2 ; Nr. 8, no. 2, S.160-169 |
| Datensatznummer |
250005493
|
| Publikation (Nr.) |
 copernicus.org/hess-8-160-2004.pdf |
|
|
|
|
|
| Zusammenfassung |
| Harvesting of clams(Tapes philippinarum) has important socio-economic and
environmental implications for the Venice lagoon area, Italy. Clam harvesting disrupts the
structure of benthic communities but the effects upon sediment stability and surface structure
remain unclear. The effect of clam fishing on the sediment properties of the lagoon bed was
investigated at two different sites, a heavily fished site (San Angelo) and an infrequently
fished site (San Giaccomo). Both sites were assessed for immediate impacts of fishing, using
indicators of biogenic sediment stabilisation. Samples were taken at three points along three
100 m linear transects at each site prior to and post fishing. Paired samples were also taken
parallel to each transect at a distance of 5m, to allow for temporal variation. Sediment
stability, measured with a cohesive strength meter (CSM), was significantly higher at the less
impacted site (F1,34 = 6.23, p < 0.018), was correlated with indicators of
biogenic sediment stabilisation and decreased by approximately 50% following the trawling
event. Concomitant decreases in chlorophyll a (chl a), colloidal-S carbohydrate
and dry bulk density were observed on the transect after fishing but not adjacent to the
fishing path. At the heavily impacted site, clam fishing by trawling had, in general, no
significant effect on the biological and physical properties (although chl a did
decrease significantly after fishing). The lack of a significant impact from fishing at the
impacted site was attributed to the higher frequency of fishing occurring in this area. Hence,
frequent fishing of the lagoon prevents establishment of biotic communities, preventing
biostabilisation and thus reduces the stability of the surface sediment.
Keywords: clam harvesting, erosion threshold, microphytobenthos, sediment, stability |
| |
|
| Teil von |
|
|
|
|
|
|
|
|