Foraging behaviour and movements of an ambush predator reveal benthopelagic coupling on artificial reefs

Abstract

The behaviour of coastal fishes to new habitats and trophic opportunities provided by artificial reefs may reveal the key processes which sustain fish production at these reefs. We quantified the trophic link between benthic predators and pelagic forage fish from the movement and foraging behaviour of an ambush predator, the bluespotted flathead Platycephalus caeruleopunctatus, around an artificial reef in relation to schools of small pelagic fish. We used a network of acoustic receivers to monitor the fine-scale movements of 48 acoustically tagged flathead around 5 groups of artificial reef modules for 8 mo in conjunction with acoustic surveys of pelagic baitfish and sustained monitoring of current speed and direction. Flathead were highly associated with the artificial reef, with 44% of detections within 10 m of the modules. Flathead had a considerable degree of fidelity to the reef system, with an average residency period of 84 d yr-1 (residency index = 0.23, SD = 24 d). Low activity was recorded by accelerometers in the north-east of the artificial reef. This coincided with high densities of forage fish which were also found inside the stomachs of the flathead. Artificial reefs with high vertical relief allow planktivores to feed through more of the water column, fixing more pelagic biomass into the system. Defining the residency and trophic connectivity of fish at artificial reefs is critical to clarify the production-attraction debate and the sustainability of fishing at artificial reefs.

Restoring marine ecosystems: Spatial reef configuration triggers taxon‐specific responses among early colonizers

“…We did not record any round gobies in this study and found no evidence that the restored reefs promoted comb jelly, which is a holoplanktonic species (Jaspers et al, 2018), relative to reference sites (Table S2). Still, these mechanisms highlight the importance of investigating effects of reef construction on soft-bottom taxa (Puckeridge et al, 2021) and of conducting long-term monitoring studies to assess temporal variabilities in restoration effects.…”

Theory, practice, and design criteria for utilizing artificial reefs to increase production of marine fishes

“…Thus, a substantial amount of literature documented specific effects of individual artificial reef deployments, the mechanisms through which increased production occurred, and design considerations for achieving these objectives. Recently there has been more focus in the literature on the specific mechanisms, sometimes referred to as "enhanced ecological functions" (Glarou et al, 2020), that lead to increased secondary production of fish on artificial reefs, even above rates observed on natural reefs (e.g., Cresson et al, 2014a;Glarou et al, 2020;Rouse et al, 2020;Puckeridge et al, 2021). These mechanisms provide benefits to individual species, typically through provision of shelter and/or food supporting survival or growth.…”

“…Zooplanktivorous fishes on artificial reefs are often the key trophic link between zooplankton and the larger reef-associated community (Bray et al, 1981;Cresson et al, 2014a;Holland et al, 2021;Puckeridge et al, 2021). Schooling water column and zooplanktivorous fishes were in greater abundance above higher relief purpose-built artificial reefs in temperate Australia (Puckeridge et al, 2021) and wrecks off of North Carolina, USA (Lemoine et al, 2019), when compared to lower relief natural reefs within each region.…”

“…Zooplanktivorous fishes on artificial reefs are often the key trophic link between zooplankton and the larger reef-associated community (Bray et al, 1981;Cresson et al, 2014a;Holland et al, 2021;Puckeridge et al, 2021). Schooling water column and zooplanktivorous fishes were in greater abundance above higher relief purpose-built artificial reefs in temperate Australia (Puckeridge et al, 2021) and wrecks off of North Carolina, USA (Lemoine et al, 2019), when compared to lower relief natural reefs within each region. An Australian study directly documented the trophic link between Bluespotted Flathead (Platycephalus caeruleopunctatus), a resident benthic ambush predator, feeding on pelagic forage fish above the high relief artificial reef modules (Holland et al, 2021).…”

Crabs ride the tide: incoming tides promote foraging of Giant Mud Crab (Scylla serrata)

“…To account for this and ensure catch rate data is a reliable index of abundance, so-called ‘catch rate standardization’ (i.e., some form of regression between catch rate and environmental covariates) must be undertaken to remove the effect of environmental variation [ 4 , 5 ]. As such, identifying specific behaviours (e.g., foraging; [ 7 , 8 ]) and quantifying the influence of environmental variation on them can be useful in standardization and interpretation of catch-per-unit-effort data [ 9 ]. Furthermore, assessing how these behaviours are allocated among different habitats can be used to inform the design of marine protected areas [ 10 , 11 ] and abundance surveys, prioritize restoration of degraded habitats [ 12 , 13 ] and target release locations for stocking of hatchery reared individuals.…”