title: Benthic molluscan macrofauna structure in heavily trawled sediments (Thermaikos Gulf, North Aegean Sea): spatiotemporal patterns.
abstract: BACKGROUND
  Spatio-temporal patterns on benthic molluscan macrofauna structure and function (feeding guilds) were investigated in a commercial fishing ground in Thermaikos Gulf (N Aegean Sea). Fishery management measures in this area include a trawling period of 8 months per year (October to May). Macrofauna samples were collected before and after 30 and 120 days of the commencement of the trawling period (temporal axis) along a southward transect (spatial axis) and down through the sediment profile (vertical axis).
  
  
  RESULTS
  Main results revealed no recognizable changes in community diversity and structure at temporal scales. This finding can probably be attributed to the fact that the examined communities are subjected to continuous disturbances deriving from multiple natural and anthropogenic stressors acting simultaneously in Thermaikos Gulf. Molluscan assemblages were already stressed before the commencement of the trawling period, indicating that the time period in which bottom trawling is prohibited is not sufficient for the recovery of benthic communities. Significant shifts in the trophic structure of molluscan assemblages were also detected. The direct mortality of herbivorous species and the loss of filter feeding organisms may be attributed to the passage of the fishing gear and to sediment re-suspension, respectively. Trawling disturbance may have created the observed vertical patterns of the community structure since hauling induces profound changes in the geochemical profile of the sediment.
  
  
  CONCLUSIONS
  Our findings sustained the notion that bottom trawling, alongside with other types of human induced stressors, can have considerable effects on the structure and function of the benthic domain. Therefore, our results highlighted the need of an Ecosystem Based Fishery Management (EBFM) perspective in Thermaikos Gulf to ensure both fisheries and ecosystem sustainability.
authors.affiliation: Department of Marine Sciences, Faculty of Environment, University of the Aegean, 81000 Mytilene Lesvos Island, Greece ; National Marine Park of Zakynthos, El. Venizelou 1, 29100 Zakynthos Island, Greece.
authors.forename: Charalampos
authors.initials: C
authors.lastname: Dimitriadis
authors.affiliation: Department of Marine Sciences, Faculty of Environment, University of the Aegean, 81000 Mytilene Lesvos Island, Greece ; National Marine Park of Zakynthos, El. Venizelou 1, 29100 Zakynthos Island, Greece.
authors.forename: Drosos
authors.initials: D
authors.lastname: Koutsoubas
authors.affiliation: Department of Marine Sciences, Faculty of Environment, University of the Aegean, 81000 Mytilene Lesvos Island, Greece.
authors.forename: Zoi
authors.initials: Z
authors.lastname: Garyfalou
authors.affiliation: Department of Maritime Studies, University of Piraeus, G. Lambraki 21 & Distomou, 18534 Piraeus, Greece.
authors.forename: Anastasios
authors.initials: A
authors.lastname: Tselepides
keywords: Bottom trawling; Macrofauna; Sediment profile; Thermaikos gulf