Dataset for the "Seasonal dynamics and environmental regulation of sessile invertebrate assemblages in natural and farmed kelp habitats" Manuscript

The study tested the hypothesis that seasonal and environmental variability influences the composition and relative abundance of sessile invertebrate assemblages, and that these patterns differ between habitats inside a kelp farm and natural reference sites. The study had two objectives: (i) to assess whether marine environmental conditions, including temperature, salinity, and total dissolved solids, influence the spatio-temporal patterns of sessile invertebrates at shearwater Bay kelp farm and Diaz Point native kelp forest; and (ii) to investigate seasonal dynamics in the composition and abundance of these assemblages, providing insights into their ecological roles in natural and farmed kelp systems.

Two complementary datasets were collected. The quarterly survey (QS), conducted at Diaz Point and Shearwater Bay, recorded abundance of sessile invertebrates on structures alongside environmental parameters. Counts and percentage cover were normalized to calculate relative abundances, and Redundancy Analysis (RDA) was used to assess correlations between environmental variables and assemblage composition. These data show that environmental factors, particularly temperature, salinity, and total dissolved solids, are correlated with relative abundances of key taxa, indicating their influence on community structure.

The experimental survey (ES), conducted at Shearwater Bay inside and outside the kelp farm, monitored specific quadrats (10 x 10cm) on structures (float tops, rope sides with tags, and block surfaces). Due to dense red algae growth, a semi- and later full-destructive approach was employed to accurately assess percent cover and visibility of sessile taxa. Temporal patterns in assemblage composition were analyzed using the Friedman test, revealing clear seasonal variability across sites and structure components.

These datasets provide detailed records of species identity, abundance, percent cover, environmental parameters, and structure-specific observations. They can be used to explore seasonal dynamics, environmental drivers, and habitat-specific assemblage patterns. Researchers can reproduce the surveys by deploying similar structures, applying fixed quadrats, recording environmental variables, and using comparable statistical approaches. Percent cover, visibility scores, and normalized abundances allow interpretation of community composition and ecological responses to environmental variability in natural and farmed kelp systems.