Total sponge bioerosion.

<p>Final rates of total erosion by the six sponge species (top) acquired through flow-through incubation (FT) and buoyant weight loss over a three week period (BW). The different bioerosive components (FT) are based on a 12 h day/night diurnal cycle. Mechanical bioerosion rates based on long-term collection are provided separately (LT). Here, a distinction is made between actual sponge chips and other CaCO₃ fragments that have been dislodged through sponge bioeroding activity. Rates are given in mg CaCO₃ cm^-2 d^-1 and kg CaCO₃ m^-2 y^-1. Error bars indicate the 95% confidence intervals for each individual element. Species and boring strategies are provided at the top of each panel, <i>CF</i>: cavity-forming, <i>GF</i>: gallery-forming; <i>NF</i>: network-forming.</p

Modelled effect of incubation time on sponge chemical bioerosion rates.

<p>Black regression lines represent the modelled (GAM) mean dissolution in mg cm^-2 h^-1 by <i>Cliona caribbaea</i> (left panel) and <i>Cliona delitrix</i> (right panel) in standing incubations. 95% confidence limits are indicated by the grey band. Solid dots show the calculated mean dissolution rates at T₁, T₂, T₄ and T₆ (ST). Open dots represent rates derived from running flow-through incubations at T₁, T₂, T₃ and T₄, dotted lines here indicate 95% confidence limits. All rates are obtained using alkalinity anomaly techniques.</p

Scanning Electron Microscopy (SEM) image of material produced by <i>C</i>. <i>caribbaea</i>.

<p>The provided image shows only a fraction of the total material produced over the 7-day collection experiment. Black arrows: some characteristic sponge chips, white arrows: other CaCO₃ fragments. Scale is provided in lower-right corner.</p

In situ close-up of the six studied excavating sponge species.

<p><b>A.</b><i>Cliona amplicavata</i> (α-stage) <b>B.</b> <i>Cliona aprica</i> (α-stage) <b>C.</b> <i>Cliona caribbaea</i> (β-stage) <b>D.</b> <i>Cliona delitrix</i> (α-stage) <b>E.</b> <i>Siphonodictyon brevitubulatum</i> (α-stage), please note that the yellow fistules of <i>S</i>. <i>brevitubulatum</i> are surrounded by a different sponge species (pink coloured) <b>F.</b> <i>Suberea flavolivescens</i> (α-stage). Black arrows in <b>A</b>, <b>E</b> and <b>F</b> point out oscula and ostia of the studied sponges.</p

Summary of all calculated sponge bioerosion rates.

<p>Summary of all calculated sponge bioerosion rates.</p

Summary of nutrient dynamics in the incubation chambers.

<p>Summary of nutrient dynamics in the incubation chambers.</p

Chemical bioerosion.

<p>Hourly rates of chemical dissolution (mg CaCO₃ cm^-2 d^-1) are given for the six studied sponge species (top). Both day (light grey) and night (dark grey) erosion rates are included. Rates are derived from alkalinity change in flow-through incubation. Error bars indicate the 95% confidence limits.</p

Matrix of pairwise population differentiation values (Φ_st) between populations of <i>Montastraea cavernosa</i> at Saba Bank and in the wider Caribbean and Gulf of Mexico.

<p>Significant values (p < 0.05) are provided in bold.</p

Population Genetic Structure, Abundance, and Health Status of Two Dominant Benthic Species in the Saba Bank National Park, Caribbean Netherlands: <i>Montastraea cavernosa</i> and <i>Xestospongia muta</i>

<div><p>Saba Bank, a submerged atoll in the Caribbean Sea with an area of 2,200 km², has attained international conservation status due to the rich diversity of species that reside on the bank. In order to assess the role of Saba Bank as a potential reservoir of diversity for the surrounding reefs, we examined the population genetic structure, abundance and health status of two prominent benthic species, the coral <i>Montastraea cavernosa</i> and the sponge <i>Xestospongia muta</i>. Sequence data were collected from 34 colonies of <i>M</i>. <i>cavernosa</i> (nDNA ITS1-5.8S-ITS2; 892 bp) and 68 <i>X</i>. <i>muta</i> sponges (mtDNA I3-M11 partition of COI; 544 bp) on Saba Bank and around Saba Island, and compared with published data across the wider Caribbean. Our data indicate that there is genetic connectivity between populations on Saba Bank and the nearby Saba Island as well as multiple locations in the wider Caribbean, ranging in distance from 100s–1000s km. The genetic diversity of Saba Bank populations of <i>M</i>. <i>cavernosa</i> (π = 0.055) and <i>X</i>. <i>muta</i> (π = 0.0010) was comparable to those in other regions in the western Atlantic. Densities and health status were determined along 11 transects of 50 m² along the south-eastern rim of Saba Bank. The densities of <i>M</i>. <i>cavernosa</i> (0.27 ind. m^-2, 95% CI: 0.12–0.52) were average, while the densities of <i>X</i>. <i>muta</i> (0.09 ind. m^-2, 95% CI: 0.02–0.32) were generally higher with respect to other Caribbean locations. No disease or bleaching was present in any of the specimens of the coral <i>M</i>. <i>cavernosa</i>, however, we did observe partial tissue loss (77.9% of samples) as well as overgrowth (48.1%), predominantly by cyanobacteria. In contrast, the majority of observed <i>X</i>. <i>muta</i> (83.5%) showed signs of presumed bleaching. The combined results of apparent gene flow among populations on Saba Bank and surrounding reefs, the high abundance and unique genetic diversity, indicate that Saba Bank could function as an important buffer for the region. Either as a natural source of larvae to replenish genetic diversity or as a storehouse of diversity that can be utilized if needed for restoration practices.</p></div

Frequency and distribution of haplotypes in populations of <i>Montastraea cavernosa</i> (A) and <i>Xestospongia muta</i> (B) in the wider Caribbean region.

<p>Haplotype frequencies provided as pie-chart per location, number of samples in brackets. Haplotype network of ITS (A) and I3-M11 (B), baes on all sequences collected throughout the wider Caribbean region. Size of circle reflects the number of individuals with a specific haplotype. Each line represents the genetic distance between haplotypes. Specific haplotype colors match those presented in the pie-charts. White circles (ITS) are haplotypes private to a certain location.</p