Browsing by Author "Pinochet Romero, Javier Antonio Roberto"

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    Intrinsic and extrinsic factors controlling biofouling dynamics on floating substrata.
    (Universidad de Concepción, 2024) Pinochet Romero, Javier Antonio Roberto; Urbina Foneron, Octavio; Thiel, Martin
    The availability of artificial floating substrata in marine ecosystems has significantly increased in recent decades, facilitating the settlement of sessile species, both native and introduced, especially in areas where natural substratum is scarce. This gives plastic a progressively more relevant role in the creation of habitats for these fouling communities. The colonization of these substrata is influenced by intrinsic factors such as surface roughness, the presence of biofilms, and larval selection. On the other hand, extrinsic factors, such as benthic predation, have a significant effect on community structure. In Chapter 1, intrinsic factors were evaluated through larval selection, using two invasive bryozoan species, Bugulina flabellata and Bugula neritina, commonly found in fouling communities. Energy expenditure during the planktonic and benthic stages, swimming and exploration behaviors prior to settlement, as well as larval selectivity in laboratory conditions on different substrata plastics, wood, and concrete—were quantified. It was observed that energy expenditure was higher in planktonic larvae than in settled larvae. Larvae of both species swam less and explored more when exposed to plastic surfaces, suggesting a preference for this substratum and lower energy expenditures associated with habitat searching. The larvae actively chose to settle on plastics rather than on wood or concrete substrata. The results suggest that Bugula larvae prefer to colonize plastic surfaces over other materials, and that the faster they adhere to artificial substrata, the lower their energy expenditure, which may contribute to greater fitness in these individuals. In Chapter 2, the structure and biomass of the fouling community were evaluated in response to benthic prefación during summer and winter. Floating PVC plates were installed during both seasons in central Chile (36˚S) until the growing fouling community caused them to sink. The plates were then moved to the seabed, where they were exposed to benthic predation, while control plates were kept in a mesh cage to prevent predator access. It was found that in summer all plates refloated, while in winter only 60% did so, with differences observed in dominant species according to their buoyancy and resistance to predation. Therefore, the structure of the fouling community influences how predation facilitates the recovery of buoyancy, as predators cannot consume all epibionts. Although previous studies had shown how fouling organisms cause the sinking of floating debris, this is the first study to provide experimental evidence that predation can reverse this process and allow debris to resurface, making it available again as vectors for the dispersal of native and invasive species. These two chapters help us understand the importance of larval selection and how settlement timing could favor the growth of certain species within the fouling community, which could potentially lead to the sinking of these floating substrata. Additionally, they demonstrate how benthic predation could recover lost buoyancy by removing epibionts.
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