Successional changes of epibiont fouling communities of the cultivated kelp Alaria esculenta: predictability and influences

Abstract

There has been an increase in commercial-scale kelp cultivation in Europe, with fouling of cultivated kelp fronds presenting a major challenge to the growth and development of the industry. The presence of epibionts decreases productivity and impacts the commercial value of the crop. Several abiotic and biotic factors may influence the occurrence and degree of fouling of wild and cultivated fronds. Using a commercial kelp farm on the SW coast of Ireland, we studied the development of fouling communities on cultivated Alaria esculenta fronds over 2 typical growing seasons. The predictability of community development was assessed by comparing mean occurrence-day. Hypotheses that depth, kelp biomass, position within the farm and the hydrodynamic environment affect the fouling communities were tested using species richness and community composition. Artificial kelp mimics were used to test whether local frond density could affect the fouling communities. Species richness increased over time during both years, and species composition was consistent over years with early successional communities converging into later communities (no significant differences between June 2014 and June 2015 communities, ANOSIM; R = −0.184, p > 0.05). The timing of species occurrences was predictable across years for all shared species. Variations in biomass, depth and position within the farm had no significant effect on species richness and composition. Results from artificial kelp mimics suggest possible hydrodynamic effects. The ability to understand succession and the timing of occurrences of fouling organisms and predict their arrival has significant benefits for the seaweed cultivation industry.

Latitudinal, seasonal and depth-dependent variation in growth, chemical composition and biofouling of cultivated Saccharina latissima (Phaeophyceae) along the Norwegian coast

“…We observed a succession of species inhabiting the surface of S. latissima, with diatoms and filamentous algae as the first visible taxa, later replaced by M. membranacea. The same pattern of variation was observed on cultivated Alaria esculenta in Ireland (Walls et al 2017). This is in agreement with the latter of the four phases of succession proposed by Wahl (1989).…”

Biofouling in marine aquaculture: a review of recent research and developments

“…Epiphytic biofouling can be controlled by growing seaweeds at high densities in rope cultures in the sea or in tank cultures on land (reviewed in L€ uning and Pang 2003), although the efficacy of this method appears species-specific, with the culture density for some species such as Gracilaria sp. and the kelp Alaria esculenta not affecting the abundance, species richness or composition of fouling species (Kuschel and Buschmann 1991;Walls et al 2017).…”

Modelling potential production of macroalgae farms in UK and Dutch coastal waters

“…Worldwide macroalgae (seaweed) production is in excess of 28 million tons per year and has doubled between 2000 and 2014 (FAO, 2014). The majority of this production ( > 95 %) is from the southeast Asian region where macroalgal cultivation is well established (FAO, 2014;West et al, 2016). The harvested macroalgae biomass is mainly used directly for human consumption, although other uses include the extraction of phycocolloids (gelling agents), animal feed, fertiliser, water remediation and probiotics in aquaculture (see Van der Burg et al, 2016;West et al, 2016).…”

“…These macroalgae aggregations have been shown to modify the surrounding environment by reducing water velocity and attenuating waves (Jackson, 1997;Gaylord et al, 2007), and by modifying sedimentation rates of suspended particles (Eckman et al, 1989). They are also associated with high biodiversity (Burrows, 2012), providing numerous ecosystem services including habitat, shelter and food for many species including fish (Hartney, 1996), benthic organisms (lobster, crabs; Bologna and Steneck, 1993;Daly and Konar, 2008), herbivorous organisms (Kang et al, 2008) and birds (Fredriksen, 2003); see also Walls et al (2017).…”