Effects of stalked barnacle extraction on a rocky shore intertidal community: Species coverage data

Description

Species coverage data were collected in an experiment conducted between 2017 and 2019 in Asturias, North Spain, at the south shore of Biscay Bay in three locations: La Cruz (43°33N, 7°01W), Las Salsinas (43°35N, 6°14W), and Las Llanas (43°33N, 6°06W). The experiment was performed on 35 x 35 cm square plots, situated approximately in the middle of the vertical distribution of Pollicipes pollicipes populations. Half of the plots were covered with cages to prevent and control exploitation, while the other half were left uncovered to allow exploitation by harvesters. The same experimental setting was used in two different years, with distinct durations. The first setting began in July 2017 and ended in July 2019 (2-year treatment duration). The second setting started in July 2018 and ended in July 2019 (1-year treatment duration). The plots were photographed at the beginning of the experiment and every 3 months thereafter, to document changes over time. Experimental harvests were photographically documented in each plot before and after the extraction. Organisms were identified to the lowest taxonomic level possible using image analysis. All species present were recorded, and their percentage cover was quantified using the point intercept method with a 100-point grid overlaid on the picture of each plot. Species present but without detectable cover were assigned an arbitrary 0.1% cover. The net coverage change (%) of P. pollicipes was calculated as 100*(final coverage - initial coverage)/initial coverage, and the extraction intensity was estimated by calculating the cumulated removal throughout the entire experiment, detected with the image analysis. The data includes the following variables: Site (Cruz, Salsinas, Llanas); Cage (Yes, No); Scientific extraction (Yes, No); Replicate (1, 2, 3); Experiment duration (1 year, 2 years); Year (2017, 2018, 2019); Month (July, October, December, April); Before/After (B = Before harvest, A = After harvest); Species coverage data in percentage. Changes in the community structure were analyzed using analysis of variance for univariate data and non-parametric PERMANOVA for multivariate, community data. To determine the species responsible for the differences among treatments, SIMPER was used, and the Shannon-Wiener index was applied to measure ecological diversity.

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