BENTHOS 2003-2005

Benthic cover data for the study sites between 2003-200

Dynamics of Coral Reef Benthic Assemblages of the Abrolhos Bank, Eastern Brazil: Inferences on Natural and Anthropogenic Drivers

<div><p>The Abrolhos Bank (eastern Brazil) encompasses the largest and richest coral reefs of the South Atlantic. Coral reef benthic assemblages of the region were monitored from 2003 to 2008. Two habitats (pinnacles' tops and walls) were sampled per site with 3–10 sites sampled within different reef areas. Different methodologies were applied in two distinct sampling periods: 2003–2005 and 2006–2008. Spatial coverage and taxonomic resolution were lower in the former than in the latter period. Benthic assemblages differed markedly in the smallest spatial scale, with greater differences recorded between habitats. Management regimes and biomass of fish functional groups (roving and territorial herbivores) had minor influences on benthic assemblages. These results suggest that local environmental factors such as light, depth and substrate inclination exert a stronger influence on the structure of benthic assemblages than protection from fishing. Reef walls of unprotected coastal reefs showed highest coral cover values, with a major contribution of <em>Montastraea cavernosa</em> (a sediment resistant species that may benefit from low light levels). An overall negative relationship between fleshy macroalgae and slow-growing reef-building organisms (i.e. scleractinians and crustose calcareous algae) was recorded, suggesting competition between these organisms. The opposite trend (i.e. positive relationships) was recorded for turf algae and the two reef-building organisms, suggesting beneficial interactions and/or co-occurrence mediated by unexplored factors. Turf algae cover increased across the region between 2006 and 2008, while scleractinian cover showed no change. The need of a continued and standardized monitoring program, aimed at understanding drivers of change in community patterns, as well as to subsidize sound adaptive conservation and management measures, is highlighted.</p> </div

Selected aspects of rhodolith beds and individual rhodoliths.

<p>(A) SSS sonogram showing flat and highly reflective bottom typical of rhodolith beds. (B) ROV image showing the typical physiognomy of the rhodolith beds. (C) Individual rhodolith consisting primarily of <i>Lithothamnion crispatum</i> with high proportion of live tissue. (D) Superficial view of a rhodolith section observed via a stereomicroscope, showing the reddish band (arrow) corresponding to the staining performed six months earlier.</p

Stereomicroscopy and scanning eletron microscopy images of a isotopic dated rhodolith.

<p>(A) A section of the rhodolith made along its longest axis. The red squares indicate the regions where fragments were removed for isotopic analysis. (bar = 2 cm); (B and C) Scanning electron microscopy images showing the typical cellular organization of CCA species circumscribing the region where the fragments were collected for isotopic dating. Note in image “C" the presence of “secondary pit-connections" (arrow) and of cell fusions (arrow head) among mineralized cell walls (Bars: B = 150 um and C = 80 um).</p

Temporal dynamics in cover (mean ± SE) of benthic organisms in the Abrolhos Bank between 2003 and 2008 considering different reef areas and habitats.

<p>Reef areas: ITA-NT – Itacolomis Reef (no-take), ITA – Itacolomis Reef (multiple-use), TIM – Timbebas Reef (no-take) and UNP – Unprotected coastal reefs. The dashed line separates the two sampling periods in which different methodologies were used (see Materials and Methods).</p

Multidimensional scaling (MDS) of benthic assemblages (i.e. relative cover of different organisms) based on Bray–Curtis similarities.

<p>Top panel: samples classified according to habitat; Bottom panel: samples classified according to reef areas. Reef areas: ARC – Archipelago, ITA-NT – Itacolomis Reef (no-take), ITA – Itacolomis Reef (multiple-use), PAB – Parcel dos Abrolhos (no-take), TIM – Timbebas Reef (no-take) and UNP – Unprotected coastal reefs.</p

Temporal dynamics in cover (mean ± SE) of benthic organisms in the Abrolhos Bank between 2003 and 2008.

<p>The dashed line separates the two sampling periods in which different methodologies were used (see Materials and Methods). Analyses of Variance (ANOVA) results: *P<0.05, **P<0.01, ***P<0.001. Homogeneous groups are identified by equal letters.</p

Map of the Abrolhos Bank, eastern Brazil, showing study sites and marine protected areas.

<p>A - Itacolomis Reef (no-take zone: sites 1–3; multiple-use zone: sites 4–10), B - Timbebas Reef, C - Abrolhos Archipelago, D - Parcel dos Abrolhos Reef, E – Unprotected coastal reefs.</p

Benthic cover (mean + SE) of the top five most abundant reef corals (secleractinians) in the Abrolhos Bank.

<p>Benthic cover (mean + SE) of the top five most abundant reef corals (secleractinians) in the Abrolhos Bank.</p

Benthic cover (mean + SE) of the top five most abundant organisms in the Abrolhos Bank.

<p>Benthic cover (mean + SE) of the top five most abundant organisms in the Abrolhos Bank.</p