Leão Zelinda M A N, Kikuchi Ruy K P
Universidade Federal da Bahia, CPGG-IGEO, Rua Caetano Moura 123, Federação, Salvador, 40210-340, Bahia, Brazil.
Mar Pollut Bull. 2005;51(5-7):599-611. doi: 10.1016/j.marpolbul.2005.04.024.
Coral species composition of drilled cores from emergent bank reefs, and coral cover of the surface of old and living reefs located along the coast of the state of Bahia, Eastern Brazil, revealed that there is a marked change in the occurrence of the major building coral species in different time intervals of the reef structure, as well as in the living surface of reefs located in two different geographical sites. Holocene core sections from two reef areas (12 degrees 40'S-38 degrees 00'W and 18 degrees 00'S-39 degrees 00'W) have as major reef builders, on its topmost core interval (3 to 4 ky old), the endemic coral Mussismilia braziliensis Verrill, 1868, which also dominate on the 2.5-3.5 ky old surfaces of truncated reef tops. At the base of the cores (the 2m lower interval, older than 4 ky BP), another endemic coral Mussismilia harttii Verrill, 1868 is the dominant reef component. The relative abundance of M. braziliensis on the living surfaces of shallow reefs from both areas, shows that in the southern area, it is up to 98% on reefs located 60 km off the coast, in depths between 3 and 4m, but do not exceed 1.3% on the surface of the northern reefs located 1-2 km off the coast in depths 4-5m. The Holocene falling sea level that occurred along the coast of Brazil since 5.1 ky BP, causes an increasing runoff into the area of coastal reefs. This phenomenon may have affected the nearshore reef building fauna, replacing a more susceptive coral fauna with one better adapted to low light levels and higher sediment influx. The high turbidity associated with early Holocene shelf flooding, should also be responsible for the absence of M. braziliensis during the initial stages of reef buildup in Brazil. At the present time, the rapidly increasing human pressure, due to changes in land uses of the coastal zone (increasing sedimentation rate, nutrification of coastal waters, industrial pollution) and underwater practices, such as overfishing and an intense tourism, is aggravating the recovery capacity of this already naturally threatened coral community. If this situation coupled with increasing sea surface temperature persists, modern coral reef growth, in Brazil cannot be maintained and the major reef building coral species of the reefs in Bahia, a remnant endemic coral fauna will very soon appear in the list of endangered species.
对巴西东部巴伊亚州沿海露出水面的岸礁钻孔岩芯的珊瑚物种组成，以及古老和现存珊瑚礁表面的珊瑚覆盖情况进行研究后发现，在礁体结构的不同时间间隔内，以及在两个不同地理位置的珊瑚礁活表面上，主要造礁珊瑚物种的出现情况存在显著变化。来自两个礁区（南纬12度40分 - 西经38度00分和南纬18度00分 - 西经39度00分）的全新世岩芯剖面，在其最顶部的岩芯间隔（距今3至4千年），主要的礁体建造者是地方性珊瑚巴西缪氏珊瑚（Mussismilia braziliensis Verrill，1868年），在截顶礁顶2.5 - 3.5千年的表面上它也占主导地位。在岩芯底部（下部2米间隔，距今超过4千年），另一种地方性珊瑚哈氏缪氏珊瑚（Mussismilia harttii Verrill，1868年）是主要的礁体组成部分。这两个区域浅礁活表面上巴西缪氏珊瑚的相对丰度表明，在南部区域，离岸60公里、水深3至4米的珊瑚礁上其占比高达98%，但在北部离岸1 - 2公里、水深4 - 5米的珊瑚礁表面，其占比不超过1.3%。自距今5.1千年以来巴西沿海发生的全新世海平面下降，导致流入沿海珊瑚礁区域的径流量增加。这种现象可能影响了近岸礁体建造动物群系，用一种更适应低光照水平和更高泥沙流入量的珊瑚动物群系取代了更易受影响的珊瑚动物群系。全新世早期陆架洪水带来的高浊度，也应该是巴西礁体形成初期巴西缪氏珊瑚缺失的原因。目前，由于沿海地区土地利用变化（沉积速率增加、沿海水体富营养化、工业污染）以及水下活动，如过度捕捞和密集的旅游业，导致人类压力迅速增加，这正在削弱这个本已受到自然威胁的珊瑚群落的恢复能力。如果这种情况加上海面温度上升持续下去，巴西现代珊瑚礁的生长将无法维持，巴伊亚州珊瑚礁的主要造礁珊瑚物种，一种残存的地方性珊瑚动物群系很快将出现在濒危物种名单中。
