Linking Species Functional Traits to Specific Biogeochemical Processes under Trawling Pressure

Abstract

The impact of otter trawling on the relationship between functional traits of benthic invertebrates and specific biogeochemical processes were investigated in the oligotrophic Cretan Sea. The fishery is managed through a seasonal closure during the summer. During two seasons (winter and summer) replicate samples were taken from the field from a commercial trawl ground and an adjacent control area. Environmental parameters related to sediment biogeochemistry were measured including particulate organic carbon, sedimentary organic carbon, bottom water and sedimentary chlorophyll a and phaeopigment concentrations as well as benthic oxygen consumption. A significant impact of trawling was recorded only for bottom water chlorophyll and sedimentary organic carbon. Furthermore, the links between species traits and specific ecosystem processes were affected by trawling, highlighting the importance of unique functional modalities on ecosystem functioning. The traits that mostly influenced benthic biogeochemistry in the control sites were related to bioturbation and burrowing activities. In contrast, in the trawled sites, the associated traits were related to more opportunistic lifestyles and deposit feeding species that do not act as bioturbators. Thus, under trawling disturbance, this shift can decouple the species-sediment relations and affect nutrient cycling.

Trawling-induced change in benthic effect trait composition – A multiple case study

“…As already reported in other studies (Tillin et al, 2006;van Denderen et al, 2015;Pommer et al, 2016;Howarth et al, 2018;Beauchard et al, 2021;McLaverty et al, 2021;De la Torriente Diez et al, 2022;Tsikopoulou et al, 2022), our results show that bottom trawling can have a selective effect on benthic trait composition, likely because of fishing gear-induced mortality. However, the present study is novel due to the specific use of effect traits with a very strong emphasis on trait compositional variation that could be solely due to trawling effect by controlling for habitat variations (partial RLQ axis), as evidenced (H1).…”

Understanding the impact of sand extraction on benthic ecosystem functioning: a combination of functional indices and biological trait analysis

“…These proxies for ecosystem functioning have already been individually applied to assess the impact of anthropogenic activities such as demersal fish trawling (Fleddum et al, 2013;Van Denderen et al, 2015;Hinz et al, 2021;Tsikopoulou et al, 2022), dredge disposal (Birchenough et al, 2012;Bolam et al, 2016;Bolam et al, 2021), sewage discharge (Nasi et al, 2023), noise pollution (Wang et al, 2022) and sand extraction (Barrio Frojań et al, 2011;Wan Hussin et al, 2012;Festjens et al, 2023) on ecosystem functioning. However, no proxy represents all processes within the ecosystem.…”