Spatial variability in intertidal macroalgal assemblages on the North Portuguese coast: consistence between species and functional group approaches

Abstract

Natural assemblages are variable in space and time; therefore, quantification of their variability is imperative to identify relevant scales for investigating natural or anthropogenic processes shaping these assemblages. We studied the variability of intertidal macroalgal assemblages on the North Portuguese coast, considering three spatial scales (from metres to 10 s of kilometres) following a hierarchical design. We tested the hypotheses that (1) spatial pattern will be invariant at all the studied scales and (2) spatial variability of macroalgal assemblages obtained by using species will be consistent with that obtained using functional groups. This was done considering as univariate variables: total biomass and number of taxa as well as biomass of the most important species and functional groups and as multivariate variables the structure of macroalgal assemblages, both considering species and functional groups. Most of the univariate results confirmed the first hypothesis except for the total number of taxa and foliose macroalgae that showed significant variability at the scale of site and area, respectively. In contrast, when multivariate patterns were examined, the first hypothesis was rejected except at the scale of 10 s of kilometres. Both uni-and multivariate results indicated that variation was larger at the smallest scale, and thus, smallscale processes seem to have more effect on spatial variability patterns. Macroalgal assemblages, both considering species and functional groups as surrogate, showed consistent spatial patterns, and therefore, the second hypothesis was confirmed. Consequently, functional groups may be considered a reliable biological surrogate to study changes on macroalgal assemblages at least along the investigated Portuguese coastline.

The role of annual macroalgal morphology in driving its epifaunal assemblages

“…meters) (e.g. Veiga et al, 2013). Recent studies have also shown the importance of the surrounding landscape in shaping the diversity and structure of invertebrate assemblages in rocky shores (Jungerstam et al, 2014).…”

“…1). Previous studies showed that annual species were abundant in these shores (Rubal et al, 2011;Veiga et al, 2013). Based on these studies and their a priori different morphologies, we selected the following six macroalgae as model species: Chondracanthus teedii (Mertens ex Roth) Kützing, 1843; Codium tomentosum Stackhouse, 1797; Dictyota dichotoma (Hudson) J.V.…”

New records of Sea Spiders (Arthropoda: Pycnogonida) for continental Portugal and notes on species distribution

“…and Mastocarpus stellatus; Foz: assemblages dominated by Chondracanthus acicularis, Codium tomentosum and Osmundea pinnatifida and Aguda: assemblages dominated by Ulva spp., Chondracanthus acicularis and Corallina officinalis. For a detailed list of macroalga species in each shore see Veiga et al (2013a).…”

Escalas de variação de comunidades bentônicas de infralitoral em ilhas pertencentes a uma área de proteção ambiental no Sudeste do Brasil: reflexões sobre processos estruturadores e subsídios para monitoramento

“…These have been tested by researchers as species surrogates to detect adequate representation of patterns of spatial variability on multiple scales, which would reduce thus the time and resources necessary for taxa identification (Smale, 2010). Veiga et al (2013) showed consistent patterns, when using functional groups and species in algal assemblages in temperate environments. Apart from a certain loss of information on wider scales, due to the increase in rare species, they confirmed that functional groups may be used as surrogates for monitoring studies and assessing spatial variability in such communities.…”

“…While presence of species varies, in the same community, a functional group remains relatively stable in time and space, thereby facilitating the observation of patterns (Steneck & Dethier, 1994). Concepts of functional groups and taxonomic resolution were proposed, based on morphological and ecological attributes (Veiga et al, 2013). These have been tested by researchers as species surrogates to detect adequate representation of patterns of spatial variability on multiple scales, which would reduce thus the time and resources necessary for taxa identification (Smale, 2010).…”