Canonical ordination plots (CAP) of gastropod assemblage composition on reefs and seagrass meadows with varying proximity to reefs.

<p>(a) <i>Posidonia</i>; (b) <i>Amphibolis</i>. ×: Reef, ▴: 0 m, ▾: 10 m ▪: 50 m, •: >300 m.</p

Total abundance (mean + SE, n = 60) of gastropods on reefs and seagrass meadows with varying proximity to reefs.

<p>(a) <i>Posidonia</i>; (b) <i>Amphibolis</i>.</p

Pairwise comparisons testing for differences in the composition of gastropod assemblages among each reef and adjacent seagrass meadows at varying proximity from each reef.

<p>Results are presented for each seagrass species and survey (survey 1 = austral summer-autumn 2006, survey 2 = austral summer-autumn 2007). The number and percentage of reefs (from a total of 6 reefs per seagrass and survey) where we detected a significant difference (P<0.01) is indicated.</p

Patterns of species density (species/area; a, b) and species richness (species/individuals; c, d) of gastropods on reefs and seagrass meadows with varying proximity to reefs.

<p>Values are means ±95% confidence intervals.</p

Contrasting patterns of amphipod dispersion in a seagrass meadow between day and night: consistency through a lunar cycle

<div><p>ABSTRACT</p><p>Changes in light intensity, typically over the course of a day, affect the dispersion of aquatic organisms at short temporal scales. Amphipods, for example, have strong behavioural responses to light conditions. In this study, we used amphipod assemblages inhabiting a <i>Cymodocea nodosa</i> seagrass meadow on the east coast of Gran Canaria Island (eastern Atlantic) to test whether short-term dispersion of seagrass-associated amphipods differed between day and night, testing the consistency throughout an entire lunar cycle. Replicated artificial seagrass units were deployed, and subsequently retrieved, during the day (from 8:00 am to 18:00 pm) and the night (from 18:00 pm to 8:00 am) on three consecutive days within each of the four moon phases of a complete lunar cycle. We collected 13,467 amphipods corresponding to 32 species and 17 families. Significantly larger abundances of amphipods were collected during the night through the entire moon cycle. The total abundance of amphipods was also affected by the moon phases; under full moon, larger abundances of amphipods dispersed into the artificial seagrass units followed by the third quarter, the new moon and the first quarter. The species density of amphipods per unit followed the same pattern. In conclusion, the short-term dispersion of amphipods living in a seagrass meadow was considerably greater during the night than the day, while dispersion of amphipods was more intense under full moon.</p></div

Uni and multivariate-ANOVA testing for differences in total gastropod abundance and gastropod assemblage composition, respectively.

<p>Results for differences in total gastropod abundance and composition between locations, reefs within locations, and distances away from reefs for each seagrass species and survey.</p

Total number of gastropod species on reefs and seagrass meadows with varying proximity to reefs.

<p>(a) <i>Posidonia</i>; (b) <i>Amphibolis</i>. The number of shared taxa between reefs and seagrass meadows at varying proximity from reefs is nested (i.e. black bar) inside each bar.</p

Mean decalcified surface percentages (n = 17) of <i>P. pavonica</i> (A) and mean pH_F levels (n = 10 to 15) (B) per site and time in an acute OA response.

<p>Sites are distributed at increasing distance from the submarine eruption from left to right. The different letters above error bars refer to significant differences (P<0.05) between sites separately for each time (<i>post hoc</i> comparisons). Error bars are + SE of means.</p

Calcified surface trend of <i>P. pavonica</i> thalli from 1978 to 2013 (A) and oceanic pH_T levels from ESTOC dataset between 1995 and 2009 (B).

<p>The X value in the equation represents the binned group number (1–12) in three year periods. s_est stands for standard error of estimate.</p

Relationship between decalcification and pH_F for an acute OA response.

<p>Relationship between mean decalcified surfaces (%) in <i>P. pavonica</i> and coastal pH_F values for all sites and times (n = 15): (RH) ‘La Restinga harbour’, (R) ‘La Restinga’, (AB) ‘Arenas Blancas’, (CM) ‘Charco Manso’ and (C) ‘La Cometa’ (control). s_est stands for standard error of estimate.</p