Functional differences in trophic structure of offshore wind farm communities: A stable isotope study

Mavraki, Ninon; Degraer, S.; Moens, Tom; Vanaverbeke, Jan

doi:10.1016/j.marenvres.2019.104868

Cited by 27 publications

(29 citation statements)

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“…Necora puber is a predator/omnivore and feeds on a combination of primary resources and invertebrate fauna. Isotope values (δ 13 C and δ 15 N) for its possible invertebrate prey resources (Table 1) were obtained from Mavraki et al (2020), who sampled these candidate prey species during the same sampling period and at the same site as reported here.…”

Section: Discussionmentioning

confidence: 99%

“…This implies that these organisms have access to a wide range of sedimentary sources, which are enriched around the base of the turbine foundations. Indeed, the biodeposition of faces and pseudofaeces by filter-feeders (mainly Mytilus edulis) growing on offshore wind turbines enriches the nearby surroundings (Coates et al, 2014), increasing both the availability, diversity and quality range of resources in the SPL and the soft substrate close to the turbines (Mavraki et al, 2020). This may well explain why organisms from deeper zones generally exhibited isotopic niches that were more stretched along the x-axis (high E values and θ < 45 • ), compared to their conspecifics from shallower zones (Reid et al, 2016;Tabak et al, 2016).…”

Section: Food Resources and Isotopic Nichesmentioning

confidence: 99%

“…Despite this general zonation pattern, some species occur in multiple depth zones or along the entire depth gradient of the turbine. These include both sessile organisms, such as the blue mussel Mytilus edulis and the anemone Metridium senile, and mobile species, such as the porcelain crab Pisidia longicornis, the brittle-star Ophiothrix fragilis and the crab Necora puber (Mavraki et al, 2020). The latter are not considered fouling organisms, but their presence is highly linked to the presence of artificial hard substrates (Lindeboom et al, 2011;De Mesel et al, 2015;van der Stap et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

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Resource Niches of Co-occurring Invertebrate Species at an Offshore Wind Turbine Indicate a Substantial Degree of Trophic Plasticity

et al. 2020

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Offshore wind farms (OWFs) in the North Sea are proliferating, causing alterations in local ecosystems by adding artificial hard substrates into naturally soft-bottom areas. These substrates are densely colonized by fouling organisms, which may compete for the available resources. While the distribution of some species is restricted to specific parts of the turbine, others occur across depth zones and may therefore face different competitive environments. Here we investigate the trophic niches of seven invertebrate species: three sessile (Diadumene cincta, Metridium senile, and Mytilus edulis), one hemi-sessile (Jassa herdmani) and three mobile species (Ophiothrix fragilis, Necora puber, and Pisidia longicornis) that occur in multiple depth zones. We hypothesized that these species would be trophic generalists, exhibiting trophic plasticity by selecting different resources in different depth zones, to cope with the different competitive environments in which they occur. We analyzed δ 13 C and δ 15 N of these species and their potential resources across depth zones. Our results show that most of these invertebrates are indeed trophic generalists which display substantial trophic plasticity, selecting different resources in different zones. Degree of trophic plasticity was not related to mobility of the species. There are two possible explanations for these dietary changes with depth: either consumers switch diet to avoid competition with other (dominant) species, or they benefit from the consumption of a non-limiting resource. Only Diadumene cincta was a trophic specialist that consumed suspended particulate organic matter (SPOM) independent of its zone of occurrence. Altogether, trophic plasticity appears an important mechanism for the coexistence of invertebrate species along the depth gradient of an offshore wind turbine.

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Section: Discussionmentioning

confidence: 99%

Section: Food Resources and Isotopic Nichesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Resource Niches of Co-occurring Invertebrate Species at an Offshore Wind Turbine Indicate a Substantial Degree of Trophic Plasticity

et al. 2020

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“…Fouling organisms inhabiting vertical hard substrates such as oil and gas platforms and offshore wind turbines produce biodeposits that sink on the seabed, causing very local accumulation of organic matter (Coates et al, 2014). The increased local organic matter accumulation provides resources for multiple species, increasing the local trophic diversity and attracting species with distinct feeding habits (Mavraki et al, 2020a). Therefore, organisms with different feeding traits are to be expected at the base (i.e.…”

Section: Ecological Importance Of the Halfweg Gbs Structurementioning

confidence: 99%

“…fouling fauna (Reubens et al, 2013(Reubens et al, , 2011. Furthermore, the introduction of scour protection layers increases the local food web complexity, supporting a high diversity of trophic levels (Mavraki et al, 2020a). The biodeposition processes of fouling organisms create organic-matter rich soft sediments near the base of offshore wind foundations, which in turn increases the abundance and species richness of the macrofaunal communities (Coates et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Ecological implications of removing a concrete gas platform in the North Sea

Coolen

Bittner²,

Driessen

et al. 2020

Preprint

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ABSTRACTArtificial structures such as offshore oil and gas platforms can significantly alter local species communities. It has been argued that this effect should be considered during decisions over their removal during decommissioning. In the North Sea, leaving such structures in place is prohibited but derogations are allowed for large concrete installations. To assess removal options for one such installation, the Halfweg GBS (gravity-based structure) a concrete platform foundation off the Dutch coast, we studied it’s resident fouling macrofauna community. The faunal structure, biomass and trophic composition of the Halfweg was then compared with those from the surrounding seabed sediments, other local artificial structures and a natural rocky reef.In total, 65 macrofaunal species were observed on the concrete (52 species), steel legs (32) and surrounding rock dump (44) of Halfweg. Mean Simpson’s diversity per sample was highest on the rock dump (0.71) but concrete (0.54) and steel (0.60) of the GBS were lower than seabed (0.69). Fourteen of the species observed on the concrete were not reported on other substrates while 10 of the species were also observed in the surrounding seabed. The GBS structure was numerically dominated by Arthropoda which comprised 98% of the total abundance. Mean ash free dry weight (AFDW) was significantly higher (p<0.001) on the Halfweg substrates (204 g AFDW per m2) than in the surrounding seabed (65 g AFDW per m2). Over 94% of the biomass on Halfweg consisted of the plumose anemone Metridium senile.While common on other reefs, this species was absent from the surrounding seabed. Macrofaunal feeding mechanisms of the concrete and rock dump communities on the GBS were comparable to those of nearby sediments, although these differed from those on the Halfweg steel legs. Multivariate analysis revealed that taxonomic structure of the GBS and other artificial structures significantly differed from that of the sedimentary habitats.Our data show that the Halfweg structures significantly increase local biodiversity and biomass. Removal of the concrete and steel legs of the GBS (leaving the rock dump) will significantly reduce local macrofauna biodiversity. The long-term impact on macrofaunal biomass is considered low. Leaving the complete Halfweg structure in place will result in the highest localised macrofaunal biodiversity.

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Widespread variation in stable isotope trophic position estimates: patterns, causes, and potential consequences

Kjeldgaard

Hewlett

Eubanks

2021

Ecological Monographs

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Stable isotope analysis is one of the most widely used techniques to estimate trophic position and provides fundamental insight into the structure and management of ecological communities. To account for the effects of geographic variation in isotope levels, trophic position is typically estimated relative to an isotope “baseline” (i.e., material representing geographic variation) using a methodology such as a formula or statistical analysis. There is, however, remarkable variation in the baselines and methodologies used to estimate trophic position from stable isotopes. The consequences of this lack of standardization are unknown but could result in biased or erroneous conclusions. We conducted a literature review to quantify the variation in baselines and methodologies used to estimate trophic position from stable isotopes. Next, we assessed the consequences of this variation on individual species estimates and food web structure by extracting published trophic positions and applying various baselines and methodologies to existing data sets. We identified 10 baselines and eight methodologies, the use of which varied by ecosystem studied. Moreover, we found that different baselines and methodologies yield significantly different trophic position estimates for individual species, as well as different conclusions about food web structure. Authors should avoid biological interpretations of absolute, stand‐alone trophic positions (as these are prone to a number of biases). We recommend pairing stable isotope analysis with other techniques for more robust conclusions. Increased sample size may mitigate some of the variation caused by different baselines and methodologies; however, an alarmingly large proportion of studies collected only one sample in at least one trophic group (41% of all reviewed studies). Authors should collect a minimum of five samples per trophic group (but ten for best practices) from as many trophic groups as possible to increase statistical power and redundancy in comparisons. When sample size is unavoidably constrained, we recommend using compound‐specific isotope analysis with a taxon‐specific trophic discrimination factor, because it may be more accurate and require fewer samples to maintain appropriate statistical power. Implementing our recommendations will increase the robustness and accuracy of conclusions based on stable isotopes, resulting in better management decisions and a more accurate understanding of ecological communities.

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Functional differences in trophic structure of offshore wind farm communities: A stable isotope study

Cited by 27 publications

References 50 publications

Resource Niches of Co-occurring Invertebrate Species at an Offshore Wind Turbine Indicate a Substantial Degree of Trophic Plasticity

Resource Niches of Co-occurring Invertebrate Species at an Offshore Wind Turbine Indicate a Substantial Degree of Trophic Plasticity

Ecological implications of removing a concrete gas platform in the North Sea

Widespread variation in stable isotope trophic position estimates: patterns, causes, and potential consequences

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