Effect of algal phenology on seasonal dynamics of gammarid assemblages: differences between canopy and understory strata in a Sargassum yezoense bed

Asymmetric effects of changes in the habitat‐forming algae Sargassum on different associated mobile faunas along São Paulo coast, Brazil

“…Overall, increasing habitat size and structural complexity is known to have a positive effect on associated mobile macrofauna, which benefits from more available refuge areas and food sources (Christie et al, 2009;Norderhaug et al, 2007;Veiga et al, 2014). This general pattern is also consistent and has already been registered separately for each of the main associated groups: for mollusks, a higher abundance, species diversity, and functional diversity were observed for assemblages associated with morphologically more complex macroalgae (Chemello & Milazzo, 2002;Veiga et al, 2018;Barbosa et al, 2019 andDuarte et al, 2020); for crustaceans, similar results were found for amphipods in Sargassum beds, presenting higher abundance and diversity in association with higher biomass and/or more complex fronds (Carvalho et al, 2018;Kodama et al, 2020); and for polychaetes, a higher abundance and diversity was observed when in association with increased biomass of an invasive macroalgae (Box et al, 2010). These positive effects are also observed in smaller organisms, such as meiofaunal assemblages, which are influenced by the macroalgal cover (Ape et al, 2018;Hicks, 1980;Losi et al, 2018).…”

“…Thus, higher biomass is usually associated with higher abundance of associated macrofauna (i.e., crustaceans, mollusks and polychaetes), as reported by Torres et al (2015) and by Chen et al (2020), that found higher abundances of the main associated groups with increasing biomass among different macroalgae species and in Sargassum beds, respectively. Studies evaluating the relationship between specific invertebrate groups and macroalgae morphological features also found similar results (Barbosa et al, 2019;Box et al, 2010;Carvalho et al, 2018;Chemello & Milazzo, 2002;Kodama et al, 2020).…”

“…In the other hand, when algae biomass and E. brasiliensis decreased, an increase in species diversity and evenness but not in species richness was observed in Spring. Detritivorous species, such as E. brasiliensis, do not directly benefit from algae biomass as a food resource and have a higher density in the algae defoliation period when the large amounts of thalli and detritus would be deposited in the understory with the algal holdfasts functioning as a trap, what happens in the lower temperature months (Kodama et al, 2020). On the other hand, when algae biomass increases from Fall to Spring (Porcos), we observe a reduction in species diversity and species evenness, due to the increase in density and dominance of hyalid species (Hyale niger, Hyale macrodactyla and Apohyale media).…”

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“…x X X X X X X X 2.0-5.9 Barnard (1969) as J. falcata thick form; Lim et al (2008); Kodama et al (2017Kodama et al ( , 2020 VAL 14-17 16-34 0-17 X X X X X X X X 2.5-6.1 Thomson (1883); LeCroy (2007); Winfield et al (2021) .......continued on the next page Delesseria, Ellisolandia, Fucus, Gelidium, Halidrys, Laminaria, Lithothamnion, Mastocarpus, Palmaria, Phyllophora, Phymatolithon, Polysiphonia, Ptilota, Saccharina, Sargassum, unidentified HER 5-18 30.5- Acoz (1993); Zintzen et al (2006Zintzen et al ( , 2008 1 Riera et al (2014) collected "Jassa marmorata" from 150 m depth at Tenerife but did not indicate that they had considered the possibility that these specimens are J. slatteryi which resembles their photographs and description and is also widespread. This depth would considerably extend the depth range known for either of these species.…”

“…Conspecifics are also known to partition algae that they cohabit, with J. marmorata preferring the algal interior over the periphery (Beermann & Boos 2015). An algal canopy can provide greater access to passing detritus but the understory can be more stable year-round when the canopy seasonally sloughs (Kodama et al 2020). This explains the differential distribution of J. morinoi in Sargassum.…”