## 4 Discussion
The impact of fishing activities on rhodoliths and corolligenous beds in the Menorca Channel was assessed in the study developed by [PERSON] et al. [38]. Their results were not conclusive in relation to the intensity effect of bottom trawling on rhodoliths beds, so changes in size and morphology of rhodoliths in the area were better explained by current velocity, depth, and rhodoliths coverage. However, the results also suggest that the reduction of the complexity of size and morphologic structure of rhodoliths could be related with the incipient effects of fishing intensity in the area, where its impact was not detected by changes in algal biomass and megafaunal species composition [68]. On the contrary, thanks to the block of environmental conditions and the comparison of areas with different bottom trawling pressure, the results obtained in the present study have shown clear effects of bottom trawling on the composition and diversity of epibenthic communities of Non-impacted compared to Low effort history areas and some recovery signals by comparing Medium effort history and High effort areas. The decrease in abundances of sponges and ascidians, a structured habitat species on sedimentary bottoms, in higher impacted areas could be related to the sensitivity of those species [69; 70] and its higher capturability by bottom trawling activity. The wide presence of megabethite species in the Menorca channel makes them a good proxy to determine the effects of fishing activities. In fact, species such as _Ascidia mentula_, _Aplidium nordmanni_, and _Suberites domuncula_ are important by-catch species of the trawling fleet in the Menorca Channel and in the whole Balearic Islands [21; 24]. The presence of those species in lower impacted areas may indicate that epibenthic communities have started to recover from the effects of bottom trawling. The same occurs with _Spatangus purpureus_, an echinoderm species that is also an important capture of the commercial fleet in the southern part of the Menorca Channel, which showed higher abundances in the Medium effort history compared to the High effort area. Another proxy to determine the effect of any impact is to evaluate the variability in size and morphology of fragile species. Ramified rhodoliths are good indicators to detect the effect of the physical impact, and changes in size and roundness in ramified (_Lithothumion valens_ and _Phynmatolith calcareum_) and nucleated (_Spongites frticulousus_) species have been found in previous works [22]. However, the low growing rates of rhodolith species [71] could be the cause that the three species considered had not yet recovered after three years of bottom trawling exclusion in the Medium effort history area. Contrary to the expected results, biomass and size of _P. calcareum_ do not seem to be affected by bottom trawling, whereas higher roundness values were found in Non-impacted and Medium effort history areas, compared to Low effort history and High effort areas, respectively. The explanation focuses on the smallest size of _P. calcareum_, with a mean size lower than 30 mm in the four areas, and this could make it less sensitive to the pass of the bottom trawl net, suffering just changes in roundness. In fact, the nets used by the trawling fleet on the continental shelf of the Balearic Islands have a 40 mm square mesh, and they are traditionally adapted to reduce by-catch of non-commercial benthic species to improve the quality of landings. The comparison of mean density of rhodoliths, estimated from beam trawl samples (130,000 kg/km\({}^{2}\) in the central part of the Menorca Channel and 309,649 kg/km\({}^{2}\) in the southern part) and commercial haults (12 kg/km\({}^{2}\) in the central part of the Menorca Channel and 52 kg/km\({}^{2}\) in the southern part) of the trawling fleet, confirms that these nets avoid rhodolith captures. The decrease in frictions between rhodoliths and commercial species by means of the reduction of the capture of rhodoliths is a relevant measure to improve the quality of landings.