Icelandic intertidal fish communities and effects of knotted wrack (Ascophyllum nodosum) harvesting

Magnússon, JT, Hawkins, SJ, Gunnarsdottir, L, Svavarsson, J and Gunnarsson, J 2025 Icelandic intertidal fish communities and effects of knotted wrack (Ascophyllum nodosum) harvesting. Journal of the Marine Biological Association of the United Kingdom, 105. 10.1017/S0025315425100301

Full text not available from this repository.

Abstract/Summary

In Iceland, sheltered rocky intertidal zones like Breiðafjörður bay are dominated by monospecific stands of Ascophyllum nodosum, providing key habitats for marine organisms. Increasing demand for A. nodosum has led to its commercial exploitation, yet impacts on fish assemblages remain poorly known. Using a novel multi-mesh netting approach, we characterised seasonal patterns in fish composition, abundance, size structure, age, and diet. Additionally, to assess the local effects of seaweed harvesting, commercial harvesting was conducted, with comparisons being made between treatment and control unharvested areas during different seasons. Nine fish species were identified, with Pollachius virens, Myoxocephalus scorpius, and Gadus morhua being the most common. Fish abundance peaked in summer, and declined the following spring, suggesting cohort turnover with juvenile gadoids relying on these habitats as nurseries. P. virens showed increased length through seasons, whereas no trends in length or abundance were observed for M. scorpius. Effects of seaweed harvesting were minimal, although fish diversity was slightly higher and G. morhua significantly larger in control plots. Stomach contents exhibited a greater diversity of prey types in harvested sites, suggesting potential impacts on trophic dynamics. These findings underscore the importance of A. nodosum-dominated habitats as nursery grounds for commercially valuable gadoids and highlight the need for a precautionary approach to seaweed harvesting to maintain ecosystem health

Item Type:	Publication - Article
Additional Keywords:	commercial seaweeds, juvenile gadoids, nursery habitats, rocky shores, sub-Arctic
Subjects:	Aquaculture Ecology and Environment Marine Sciences
Divisions:	Marine Biological Association of the UK > Coastal Ecology
Depositing User:	Ms Kristina Hixon
Date made live:	07 Aug 2025 08:27
Last Modified:	07 Aug 2025 08:27
URI:	https://plymsea.ac.uk/id/eprint/10487

Actions (login required)

View Item