Theme session K
Introducing man-made structures in marine systems: assessing ecological effects, knowledge gaps and management implications
Thursday 21 September, 10:30–12:00 & 14:00–16:00
Room: Grand ballroom H
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Marine systems are increasingly being populated by a large variety of man-made structures, including oil and gas installations, anchored buoys, ship wrecks, pipelines and recently an exponential increment in renewable energy structures.
Aforementioned structures may present small oases for sessile epifauna as they modify the area, introducing artificial hard substrate onto a predominantly soft sediment environment. The biomass on these structures is estimated to be up to 500-fold the biomass as found on surrounding soft sediment. Very little is known about the likely effect of increased biomass may have on their immediate surroundings. Particularly, it is important to understand the level of influence that man-made structures will have in the environment and what will be the specific ecological footprints on a particular ecosystem.
The effects of introduced structures are expected to be dependent on the type of structure, as well as manifold over many levels in the marine ecosystem. For example, large offshore man-made structures such as oil and gas installations, and wind turbines span the entire water column, thereby connecting surface layers with the seafloor sediments and consequently differ from seafloor restricted natural and man-made hard substrate (e.g. pipelines, ship wrecks). Offshore structures can alter biodiversity with direct consequences on ecological functioning on different scales. Furthermore, these structures provide habitat for a fouling community, often new to offshore regions, potentially serve as stepping stones for range-expanding (non-indigenous) species, provide habitat and shelter for marine (fish) species, and alter biological and biogeochemical processes in the water column and at the seafloor, either directly (e.g. scouring, organic matter export from piles) or indirectly (e.g. cessation or displacement of fisheries).
Scientific knowledge on structural impacts on ecosystem components has significantly increased over the last years. An understanding of the effects at the ecosystem functioning level (e.g. trophic interactions, nutrient cycling and dispersion) is still in its infancy. However, knowledge on the key functions (structure and processes) that support stability and resistance of the benthos is inevitable. Thereby, it is most important to consider scales that are ecologically relevant in time and space.
Understanding on the cause-effect relationship and the consequences for ecological functioning is an indispensable prerequisite to discriminate effects through offshore structures from the natural background variability and thus forms a scientific base to underpin the development and the application of advanced management and conservation tools to enable the sustainable use of these ecosystems.
This session welcomes all contributions considering the effects of offshore structures on marine systems, including direct effects on organisms and ecosystems, but also considering the wider societal perspective. In this session, we welcome submissions on the following topics:
man-made structures as new hard substrate habitats and interactions with the soft bottom community;
effects of man-made structures on the surrounding habitats;
modelling approaches to understand effects of offshore structures on the seafloor;
changes in ecological functioning, e.g. such as biogeochemistry and food web interactions;
large-scale effects of habitat changes and ecosystem functioning;
spatial management strategies accounting for large-scale man-made structures;
the effect of man made structures as vectors on the spatial distribution of species (e.g. Stepping stones effects)
