Rapid re-establishment of top-down control at a no-take artificial reef

Abstract

Establishment of artificial reefs and no-take areas are management measures available for restoring deteriorated marine ecosystems, compensating for habitat loss and strengthening harvested populations. Following the establishment of no-take artificial reefs in western Sweden to compensate for hard bottoms lost to a shipping lane, we detected rapid positive effects on crustaceans and demersal fish compared to fished reference areas. The relative abundance and size structure of European lobster (Homarus gammarus) increased strongly in the no-take area indicating more than doubled and tripled egg production in 5 and 10 years, respectively. For benthic fish and crustacean communities, the abundances of gadoids and wrasses increased and the abundances of small decapod crustaceans decreased in the no-take area, likely indicating cascading effects of increased predation. The study demonstrates that relatively small no-take areas, enhanced by artificial reefs, can rapidly invigorate populations of lobster and fish that in turn may re-initiate local top-down control.

Assessing the Conservation Value of Artificial and Natural Reefs via Ichthyoplankton Spatio-Temporal Dynamics

“…The results show a patchy distribution of ichthyoplankton with a clear spatial distribution characteristic for both the ARs and NRs in the studied area, suggesting that ARs, as no-take sites, can be an effective tool for both fishery management and biodiversity conservation [25,76]. However, to ensure that ARs indeed enhance productivity, further research is needed, specifically extended temporal and spatial (different depths) sampling, which will provide a comprehensive and more reliable layout of the long-term distribution patterns.…”

“…Since the reproductive activities of fish determine the presence and distribution of their early developmental stages [16,53,54], the predominance of the egg stage (mainly early development) and yolk sac larvae in the ichthyoplankton samples implies that the studied reefs may serve as spawning grounds for various reef species [21][22][23][24][25]. Although the dominant ichthyoplankton species in both the natural and artificial reefs were nearly identical, supporting the hypothesis that a mimicking of fish communities may occur when artificial reefs are closer to natural reefs [40], the ichthyoplankton community assemblages varied at the species level.…”

Contrasting management regimes indicative of mesopredator release in temperate coastal fish assemblages

“…Implementing MPAs in areas that are showing signs of ecosystem dysfunctions have recently shown promising results (Kraufvelin et al, 2022;Soler et al, 2015), especially for top predator abundance in species result in more complete food webs (Rooney et al, 2006;Worm & Duffy, 2003), MPAs offer better prey choices and availability which leads to increased abundance and better diet composition of species (Dell et al, 2015). Greater phenotypic diversity (see Fernández-Chacón et al, 2020) of protected species may also confer ecosystem benefits, reinforcing the effect of functional roles changing throughout ontogeny and lifetime of long-lived, large-bodied species often absent from heavily harvested seascapes.…”

“…In the adjacent Öresund (The Sound), a de facto ban on bottom trawling in effect since 1932 has allowed cod to prosper, and the population maintained broad size and age structure also during periods of adverse environmental conditions (Lindegren et al., 2010 ; Sundelöf et al., 2013 ). Implementing MPAs in areas that are showing signs of ecosystem dysfunctions have recently shown promising results (Kraufvelin et al., 2022 ; Soler et al., 2015 ), especially for top predator abundance (Colléter et al., 2012 ; García‐Rubies et al., 2013 ). As greater diversity in species result in more complete food webs (Rooney et al., 2006 ; Worm & Duffy, 2003 ), MPAs offer better prey choices and availability which leads to increased abundance and better diet composition of species (Dell et al., 2015 ).…”

Securing sustainable access to aquatic foods

“…Additionally, there are other ongoing projects with reconstruction of lost habitats such as artificial lobster reefs in the Gothenburg archipelago (Kraufvelin et al 2022).…”