@article{Fock:334336,
      recid = {334336},
      author = {Fock, Heino and Dammann, Robin and Mielck, Finn and  Lauerburg, Rebecca A. M. and López Ganzález, Alfonso and  Nielsen, Pernille and Nowicki, Margarethe and Pauli,  Matthias and Temming, Axel},
      title = {107Auswirkungen der Garnelen-fischerei auf Habitate und  Lebensgemeinschaften im Küstenmeer der Norddeut-schen  Bundesländer Schleswig- Holstein, Hamburg und Niedersachsen  (CRANIMPACT)},
      address = {2023-05-03},
      number = {1421-2023-625},
      series = {107},
      pages = {V, 227},
      month = {May},
      year = {2023},
      note = {DOI:10.3220/REP1681989003000},
      abstract = {Study design The CRANIMPACT project investigated the  effects of beam trawl shrimp fisheries on 2 predominant  fisheryrelevant habitat types in the sublittoral of the  Wadden Sea National Parks of the northern German states.  Two complementary approaches were used to investigate the  short-term effects following an experimental fishing event  and the chronic changes caused by sustained fishing  pressure of varying intensity. In the experimental  approach, the short-term, small-scale effects on endo- and  epifauna after experimental fishing and their effect  duration were investigated on a total of 4 study sites (A,  B, B2 in the tidal flat system of the Sylt backshore tidal  flat; C in the tidal flat system near Norderney). The  experiments were conducted as before-after-control-impact  studies (BACI) exclusively in habitat type fine and medium  sands with ripple structure (a sufficiently large lanice  field could not be sampled). The large-scale and chronic  effects of fishing were determined along gradients of  fishing intensity in the Wadden Sea of Lower Saxony,  Schleswig-Holstein and Denmark. For this purpose, among  other things, methods were developed to represent  small-scale differences in fishing effort using satellite  data in tidal flat systems. Gradient analysis (GA) was  carried out on fine and medium sands with ripple structure  as well as on fields with colonization of the tree tube  worm Lanice conchilega for the endofauna alone. All surveys  were conducted in the sublittoral. A total of 427 endofauna  samples and 52 epifauna samples were examined from 2019,  2020, and 2021. Results Results from 28 stations were  included in the gradient analysis (GA). As a reference  area, 5 sites were located on tidal flats in the Danish  Wadden Sea, where fishing has been prohibited since 1977.  The community analysis of all stations in the GA revealed 2  main associations: A Bathyporeia spp. association on fine  and medium sand and a Lanice conchilega association on  substrates with increased silt content. In both  associations, sub-associations could be identified that  could be differentiated based on fishing intensity. Besides  fishing intensity, only silt content in the sediment  exerted a significant effect on faunal composition. The  explicitly included natural disturbance was not  significant. However, these two factors explained only just  under 20 % of the total variability of the endofaunal  community. Of this, 10.3% explanatory contribution came  from the level of silt content and 8.9% from differences in  fishing intensity. The high similarity of some stations  from the no-fishing area with stations with low fishing  intensity can be interpreted as the endofauna being  resilient to low fishing intensity, which can be explained  by adaptation to the existing, comparatively high natural  disturbance in the Wadden Sea. In contrast, at stations  with high fishing intensity, the total biomass of endofauna  increased with increasing fishing intensity in both  associations. The significant highest value of 39.5 g  ash-free dry weight per m² was measured in the intensively  fished Lanice conchilega sub-association at about 100 hours  of fishing per year and km². The 'biological-traits'  analysis showed that at these stations with high fishing  intensity, community characteristics also changed and the  abundance of small species < 1 cm body size decreased,  while the abundance of larger predatory species increased.  Disturbance in the Before-After-Control-Impact experiments  (BACI) was established by 4-fold fishing with a commercial  shrimper to ensure that the area of the experiment was  affected by short-term but significant fishing disturbance.  Significant spatiotemporal variability was detected for the  endofauna through ANOSIM analysis. Significant differences  were also found for individual variables or taxa between  the experimentally fished and control plots. In the fewest  cases, the differences were consistent across all  experiments. In the sum of all considered taxa as well as  total number and biomass of all analyzed animals in the  respective experiments, no statistical clustering of  significant results was found for the differences between  disturbance and control after experimental fishing  (p=0.23). Where significant negative abundance effects  occurred, caused by changes in Bathyporeia spp. or  spionids, among others, the modeled effect duration was in  the range of 13-20 days and can thus be characterized as  short-term. The epifauna was characterized by a few species  with high continuity, i.e. species that appeared in almost  every sample. In the BACI experiments, in contrast to the  endofauna, no significant small-scale variability could be  detected in the undisturbed samples. Reasons for this are,  on the one hand, the high constancy of the species  inventory, but on the other hand also a small number of  samples resulting from the comparatively large space  required for the hauls with the beam trawl. There was also  no statistical clustering of significant test results for  the difference between control and disturbance. Individual  effects at the species level were detected for Crangon  crangon and Asterias rubens. In experiment B2 off List, the  so-called "scavenger effect", i.e. the immigration of  epibenthic, scavenging species after the fishing  disturbance, was additionally investigated. Such an  overcompensation effect by food opportunists could not be  proven. Conclusions The close-meshed sampling from the  experiments showed that the habitat types studied are  characterized by considerable small-scale variability in  the predominant communities, which made the detection of  fishing impacts difficult. Nevertheless, for individual  parameters or species of both endo- and epifauna,  significant influences by experimental fishing could be  detected. In the overall picture, however, this was not  reflected in a statistically significant accumulation of  effects due to fishing disturbance. Where effects were  measured at the species level, the modeled effect duration  ranged from 13 to 20 days. In the summary meta-analysis of  all experiments, fishing effects were confirmed for total  abundance and biomass of endofauna at 4-fold impact level  while being insignificant if scaled to a single haul, and  for Crangon crangon among epifauna. Consistent with these  experimental results, communities in gradient analysis (GA)  were found to be resilient to low fishing intensities and  changed at high fishing intensities. The former can be  interpreted as an adaptation to the comparatively high  natural disturbance in the Wadden Sea and by small-scale  local exchange processes of drift fauna between disturbed  and undisturbed areas, which overlaid possible effects of  shrimp fishing. At higher fishing intensities, shifts in  communities to so-called "high fishing effort  subassociations" occurred in the gradient analysis. The  transition to these communities was observed at fishing  intensities of 19.7 to 23.2 hours per year per km2. From  the gradient analysis, the overall fish-free effect on  endofaunal composition can be reported as 8.9%. Against the  background of the heterogeneous distribution of fishing  intensity in tideway systems and the local exchange  processes between disturbed and undisturbed areas, which  are essential for recolonization times, it can be concluded  that the benthic communities on fine and medium sand with  ripple structure in unfished and lightly fished tideway  areas are in a resilient state. To what extent the present   communities are also a result of the long-term fishing  exploitation of the North Sea cannot be answered with the  research approaches from CRANIMPACT, as well as the  question of the fishing impact on other, rare or especially  sensitive habitats not considered in this study. The impact  of fishing is always a result of the specific combination  of fishing gear, habitat and species community and is not  directly transferable to other combinations.},
      url = {http://ageconsearch.umn.edu/record/334336},
      doi = {https://doi.org/10.22004/ag.econ.334336},
}