A modern perspective on the commercial seaweed landscape of Ireland

Abstract

In Ireland, seaweed was historically commercially used as a raw material to produce high-volume, low-value commodities, mostly animal feed. More recently, and due to the increasing mainstream acceptance of seaweed, there has been a renewed vigour in the Irish seaweed industry. The harvesting and gathering of “wild” seaweeds continue to play an integral role in many coastal societies, often being intrinsically linked to the cultural identity of those coastal communities. However, given the increasing commercial interest in seaweed, certainly now at a point greater than at any stage in Irish history, it is critically important that the sustainability of the resource is ensured. This thesis describes themes important to the continued evolution of the Irish seaweed commercial landscape. Chapters 2 and 3 focus first on the seaweed resources of Irish waters and how the seaweed industry has changed, adapted, and progressed in the 21st century. The second part (Chapters 4 and 5) focuses on the potential issues relating to levels of arsenic in seaweed. Seaweed has a long history of use as a supplemented livestock feed, providing nutrients and vitamins essential to maintaining animal health. However, seaweeds such as Ascophyllum nodosum are well-known accumulators of the metalloid arsenic. As the global demand for livestock produce grows, there exists concern that consumption of livestock produce reared on a diet supplemented with seaweed may pose a threat to the human population due to the potential transfer of naturally occurring arsenic present in seaweed. A population-exposure assessment was carried out using arsenic data from a commercially available seaweed meal from 2012 to 2017. A “Monte Carlo” simulation model was developed to characterise the feed to food transfer of Arsenic from animal feed to animal produce such as beef, milk, chicken, and eggs. To further address potential concerns and provide end-users, including industry, consumers, policymakers, and regulators, with information on the exposure associated with arsenic in commercial seaweed animal feed, the estimated daily intake of arsenic was calculated to evaluate potential human exposure levels. Chapters 6 and 7 describe the use of “Earth Observation” technologies to monitor some native and invasive seaweed blooming species in eutrophic North-East Atlantic estuaries and reconstruct the historical development of seaweeds using free-to-access satellite imagery (Landsat and Sentinel) utilising appropriate modelling to express the influence of environmental factors on bloom-forming seaweed development. Studies described in Chapters 6 and 7 are the first to utilise satellite imagery to reconstruct the historical development of blooms in European waters. Finally, in Chapter 8, a general discussion of the thesis is provided, concluding the thesis's primary findings while providing recommendations supporting the continued development of Ireland's commercial seaweed industry.