GEOGRAPHY

Individual corals become smaller and adapt to land-source debris imports during the Late Paleozoic Ice Age


Recently, Le Duo, associate researcher of Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, revealed the relationship between terrestrial debris input and individual size changes of reef-building corals at the beginning of the late Paleozoic ice age through systematic research. The research results were published online in the Proceedings of the Royal Society Series B on May 24.

“Today’s land-based debris imports have a severe impact on marine coral reefs, often accompanied by the death or morphological changes of reef-building corals.” “Similar phenomena have occurred in geological history, but the current understanding of how reef-building corals respond to land-based debris inputs is still unclear,” Joy said. ”

It is understood that the late Paleozoic ice age is the only period close to the concentration of CO2 in the modern atmosphere since the flourishing of automatic plants on Earth. Therefore, the study of the marine bio-environmental evolution of the late Paleozoic era can provide reference and enlightenment for the evolution of today’s marine ecosystem.

Significant Hercynian orogeny and land plant flourishing occurred during the Middle to Late Mississippian Period (Constitutional Period-Schörphoff period), which together led to increased terrestrial chemical weathering and increased land-based detritus and nutrient input, which in turn led to rapid global climate cooling and sea level reduction.

The latest study found that a significant positive bias occurred in the oxygen isotope of the brachiopod shell in the late Venetian period, which in turn indicates that the temperature of the paleo sea water decreased significantly during this period, which may represent the beginning of the main curtain of the late Paleozoic ice age. In addition, marine coral reef systems collapsed during this period, with attendant declines in benthic biodiversity.

“The study of the morphological size of reef-building corals in the middle to late Mississippian period can provide new insights into the evolution trend of reef-building corals under the influence of terrestrial source imports.” Yao Le told China Science News.

Yao Le et al. counted the individuals, sizes, parameters (single skeleton diameter, transverse belt diameter and number of next doors) of four different sedimentary facies profiles in Yashui, Hunan Malanbian, Anhui Wangjia Village and Jianshanzi in Inner Mongolia, and studied the elemental content of reef-building corals and surrounding rocks.

The results show that in the Shelpuhof period, the individual reef-building corals gradually become smaller from shallow-water open carbonate facies, carbonate-clastic excessive facies to shallow clastic facies in the South China Plate, and the content of silicon, aluminum and phosphorus in the surrounding rock increases significantly.

“On a long-term scale, based on the individual size data of Lithostrotion decipiens and Siphonodendron pauciradiale in the middle to late Mississippian period in China, Western Europe and North Africa, we found that the individual reef-building coral decreased significantly in the late Constitutional period, which is consistent with the increase in terrestrial weathering and land-based debris input accompanying the main curtain of the late Paleozoic glaciation.” ”

“Our study suggests that the onset of the Late Paleozoic Ice Age and the increase in terrestrial debris and nutrient input are the main factors controlling the phenotypic plasticity of reef-building corals, which can adapt to the paleoenvironmental changes accompanying the Late Paleozoic Ice Age by becoming smaller individuals.” “The study also found that reef-building corals with strong phenotypic plasticity, that is, reef-building corals that can make individuals smaller, may be more adaptable to environmental changes such as terrestrial debris input and water hypoxia,” Joy concluded. (Source: Shen Chunlei, China Science News)

Reef-building coral fossils Photo courtesy of interviewee

Related paper information:https://doi.org/10.1098/rspb.2023.0220



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