BENTHIC FORAMINIFERA AS ENVIRONMENTAL PROXIES IN COASTAL HABITATS OF RAS MOHAMED NATURE RESERVE, SOUTHERN SINAI, RED SEA, EGYPT

The Red Sea is globally recognized for its exceptional diversity of marine environments. Unfortunately, as elsewhere, anthropogenic activities are resulting in degradation of its coastal environments, including its coral reefs. We examined foraminiferal distributions, from which we calculated diversity and other indices to assess the ecological potential for coral-reef environments to thrive in the coastal area of the Ras Mohamed Nature Reserve in the southern Sinai region. Sediment samples were collected in mangrove, shallow-lagoon, nearshore, and coral-reef habitats. Overall, 95 species were recorded. Five benthic foraminiferal species that host algal symbionts dominated the assemblages, representing ~60% of the assemblages, along with one porcelaneous heterotrophic species (Quinqueloculina seminulum, ~8%). The symbiont-bearing species were three porcelaneous forms (Amphisorus hemprichii, Peneroplis pertusus, P. planatus) and two hyaline species (Amphistegina lobifera, A. lessonii). Peneroplis and Amphisorus dominated the hidden bay and mangrove-channel assemblages whereas Amphistegina were most abundant in reef sediments. The results of diversity and heterogeneity indices, including the Shannon–Wiener index (H'), the Simpson index, and the Evenness index (E); were remarkably consistent. The foraminiferal assemblages are characterized by moderate diversity and evenness, and high dominance. Values of the FoRAM index consistently exceeded 4, indicating water quality suitable for reef growth and accretion. The high water quality also was reflected in high percentages of foraminifers collected live (stained), up to 18% of the total assemblage in some localities. The seemingly low Fisher-alpha indices and commonly observed “abnormal” specimens reflect that these metrics must be used with caution when assessing tropical-subtropical shallow-water assemblages. Benthic species that host algal symbionts are a tiny fraction of total numbers of benthic species, yet photosynthesis by the algal symbionts allow dominance of those few in clear, relatively shallow, reef-associated waters where particulate food is limited. In addition, morphological variability is extremely common in peneroplids and soritids for reasons not fully understood.