Macroalgal vegetation on a north European artificial reef (Loch Linnhe, Scotland): biodiversity, community types and role of abiotic factors

Konstantinos Tsiamis,Martin D J Sayer,Andrew O M Mogg,Vasilis Gerakaris,Elizabeth S Porter,Frithjof C Küpper,Maria Salomidi

doi:10.1007/s10811-019-01918-2

Abstract

Very little is known about the marine macroalgae of artificial reefs—especially in the North Atlantic—despite the growing number and extent of man-made structures in the sea, and even though seaweed communities have paramount importance as primary producers, but also as feeding, reproductive and nursery grounds in coastal ecosystems. This paper explores the macroalgal diversity of a large system of artificial reefs in Loch Linnhe, on the west coast of Scotland, in a quantitative and qualitative study based on diving surveys and correlates the observations with the prevalent abiotic factors. The study was conducted in order to test the hypothesis that artificial reefs can enhance seaweed habitats—in particular, for kelps—and that there is a clear correlation with substrate type. While the reef is home to a large range of biota and abundance of early-successional species of turf and bushy macroalgae, totalling 56 taxa and with Delesseria sanguinea as the dominant species, canopy-forming perennial kelp species are conspicuously relatively rare. Macroalgal vegetation is explored in correlation with reef geometry/geography and depth. Statistical analysis shows benthic communities were strongly affected by substrate type, with turf algae and invertebrates dominating the artificial reefs, while bushy algae dominate the natural ones. Common macroinvertebrates associated with the phytobenthic communities are assessed qualitatively.

Highlights

IntroductionOther approaches aim at diverting existing impacts from recreational scuba diving from heavily impacted natural reefs (Tynyakov et al 2017)
Electronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.Artificial reefs (ARs) are artificial underwater structures which are usually built to protect or enhance marine biodiversity, including commercial species, in areas with an otherwise featureless sea bed (Sayer 2019)
Kelps (Laminariales) and fucoids (Fucales), are major structuring elements on rocky shores of the UK, forming large intertidal and subtidal forest-like communities. Such brown algal forests are important feeding, reproductive and nursery grounds for a plethora of marine animals, and enhance coastal protection (Bartsch et al 2008) and coastal atmospheric/climatic processes. Despite their overall ecological importance, algae have rarely been studied in the context of artificial reefs—even though such structures are getting more and more common, in the UK and worldwide, intentionally and unintentionally

Summary

Introduction

Other approaches aim at diverting existing impacts from recreational scuba diving from heavily impacted natural reefs (Tynyakov et al 2017). In many cases, they are built with objects which originally had a different purpose—such as oil platforms, shipwrecks, vehicle tires or subway carriages. There is growing interest in artificial reefs in the context of offshore oil platform decommissioning. The increasing development of offshore wind farms and other marine renewable energy installations has raised interest in artificial reefs—ideally, in order to address several objectives in parallel such as power generation, coastal protection and enhancement of fish stocks and marine biodiversity (Lopes de Almeida 2017).

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