Symbiont-bearing Foraminifera from Reefal Areas: a Case Study from Rio Grande Do Norte (rn, Brazil)

Abstract

We examined the abundances of two species of benthic foraminifera that host algal endosymbionts (SBF) in two sedimentary reefal areas (Pirangi and Maracajaú) of Rio Grande do Norte (RN, Brazil). The original dataset is based on 95 samples collected in winter in 2013 and 2014 by divers or grab samplers, and is compared to other known Brazilian reefs. The tests of Amphistegina gibbosa were conspicuous in sediments associated with coral and coral-rubble substrata, whereas tests of Amphisorus hemprichii were best represented in sediments associated with seagrass. Our studies also have revealed that populations of these species are depauperate near tourism sites in Pirangi, as the area is affected by trampling from tourist activities. In the Maracajaú area, these populations are healthier, except at sites severely affected by tourism. Differences in microhabitats of the two taxa are likely to be associated with the degree of anthropogenic influence on the inner shelf at Pirangi compared to the offshore Maracajaú area.

Checklist, assemblage composition, and biogeographic assessment of Recent benthic foraminifera (Protista, Rhizaria) from São Vincente, Cape Verdes

“…In fact, 17 of 26 well preserved Amphistegina specimens of the dead assemblage from Sao Pedro are dextrally coiled and show 12 to 14 chambers. The Cape Verdean specimes show a high variability from plano-convex to biconvex shape, as it has been observed off Brazil (Eichler et al 2019). The thickness of most tests resembles the High Light morphotype of Hallock et al (1986, there Figure 4).…”

On the Impact of Brazil's Largest Recent Oil Spill on Regional Oceans

“…This specific site of Pirangi was studied in 2013 and 2014 with no spotting of oil patches or other forms in the sediment and in the water in according to [24] . After the oil spill, we sampled new sediment sites in October 2019 to compare with the same methodology described in by the abovementioned authors.…”

“…In October of 2019, after the oil spill, we focused on the Pium river area and sampled 15 more sediment, reefs and microalgae, and water samples to observe the presence of oil. Processing of marine sediments followed standard procedures from [24,54] where a fixed volume of 50 cm 3 of sediment was washed over a 63 µm sieve to retire silt and clay and spot oil in analyzed sediment.…”

“…The organisms that do not die may chronically incorporate the toxic substance in their tissues, which then accumulates along the food chain [25] . Another serious consequence of crude oil in the sediment is the acidification and subsequent dissolution of calcium carbonate shells, ranging from microorganisms (foraminifera) to macro organisms (mollusks) as already evidenced by [24] .…”

“…Our paper deals with a specific site, the "Pirangi Reef area", which was subjected to the oil spill In October 2019, and was previously studied in 2013 and 2014 with no spotting of oil patches in the sediment or in the water [24] . After the oil spill, we sampled new sites to compare and discuss questions on the human-induced changes on the reef system; therefore, water and surface sediments were recovered from areas of small reef patches near tourism boating sites.…”