Subtidal Rocky Shore Communities of the Azores: Developing a Biotope Survey Method

Abstract

At 23 sites selected randomly around the island of Sã o Miguel (Azores), video records were made at the depths of 5, 10, 15, 20, 25, and 30 m where a rocky substratum was present. Semiquantitative abundance data of the most common benthic organisms (algae and fixed/sedentary macroinvertebrates) were recorded in the vicinity of each depth reference point. Qualitative samples of the more conspicuous organisms were taken for confirmation of identification in the laboratory. At each site, substratum type, geographical orientation, and depth level were recorded. Multivariate analysis (nonmetric multidimensional scaling; analysis of similarity [Anosim] tests; similarity percentages [Simper] analysis) on the collected data enabled patterns of community distribution to be identified, as well as their relationship to abiotic factors. Since depth was found to be the sole determining factor for communities, it was the only one considered in the subtidal biotope survey protocol proposed here. ADDITIONAL INDEX WORDS:Methodologies, rocky shores, quantification, image.

Effects of coastal orientation and depth on the distribution of subtidal benthic assemblages

“…As expected, and unlike coastal orientation, there were generally differences in the structure of benthic assemblages associated with depth, as had been previously described for the region (Wallenstein et al . ,b). However, in 10 of the 13 taxa examined, such differences were highly variable among locations.…”

“…whereas at deeper levels (~30 m), communities are dominated by Zonaria tournefortii and encrusting coralline algae (Wallenstein et al . ,b). At intermediate depths (10–20 m), communities are a mixture of both shallow and deeper water communities (Wallenstein et al .…”

“…At intermediate depths (10–20 m), communities are a mixture of both shallow and deeper water communities (Wallenstein et al . ,b). Invertebrates, although common, rarely occur at high densities.…”

Non-Native Marine Macroalgae of the Azores: An Updated Inventory

“…Northwestern Pacific [10] São Miguel [10,11,24,29]; Santa Maria [10,11,22,30]; Terceira [10]; Graciosa [10,11,21,29,31]; Pico [10]; Faial [10,11,29]; Flores [23] Unknown [10] 1990 [29] Family Scytosiphonaceae…”

“…Formigas [16]; Santa Maria [22]; Graciosa [21]; Pico [20]; Faial [17]; Flores [23] Unknown 1989 [20] Petalonia binghamiae Western Pacific [10] São Miguel [9][10][11]24,[31][32][33], Terceira [9][10][11]19,31,32]; Graciosa [10,11,21,31]; Pico [9][10][11]20,31,32]; Faial [9][10][11]32,34] Ballast water, Hull fouling [10] 1989 [34] Scytosiphon dotyi + 1 Indo-Pacific [35] Formigas [16]; São Miguel [26] Hull fouling [36] 1990 [26] Table 1. Cont.…”