Evolution of life in the ocean changed 170 million years ago

July 1, 2019
Source:
University of Plymouth
Summary:
New research identifies a previously overlooked global event which changed the course of the evolution of life in the oceans. It coincided with a rise in calcium carbonate-secreting plankton and their subsequent deposition on the ocean floor.

The ocean as we understand it today was shaped by a global evolutionary regime shift around 170 million years ago, according to new research.

Until that point, the success of organisms living within the marine environment had been strongly controlled by non-biological factors, including ocean chemistry and climate.

However, from the middle of the Jurassic period onwards (some 170 million years ago), biological factors such as predator-prey relationships became increasingly important.

Writing in Nature Geoscience, scientists say this change coincided with the proliferation of calcium carbonate-secreting plankton and their subsequent deposition on the ocean floor.

They believe the rise of this plankton stabilised the chemical composition of the ocean and provided the conditions for one of the most prominent diversifications of marine life in Earth’s history.

The research was led by academics from the University of Plymouth’s School of Geography, Earth and Environmental Sciences and School of Computing, Electronics and Mathematics, in cooperation with scientists from the University of Bergen in Norway, and the University of Erlangen-Nuremberg in Germany.

PhD candidate Kilian Eichenseer, the study’s lead author, explained the impact of calcifying plankton: “Today, huge areas of the ocean floor are covered with the equivalent of chalk, made up of microscopic organisms that rose to dominance in the middle of the Jurassic period. The chalky mass helps to balance out the acidity of the ocean and, with that balance in place, organisms are less at the mercy of short-term perturbations of ocean chemistry than they might have been previously. It is easier to secrete a shell, regardless of its mineralogy, if the ocean chemistry is stable.”

The aim of the research was to test the hypothesis that the evolutionary importance of the non-biological environment had declined through geological time.

Since its emergence more than 540 million years ago, multicellular life evolved under the influence of both the non-biological and the biological environment, but how the balance between these factors changed remained largely unknown.

Calcified seashells provide an ideal test to answer this question, as aragonite and calcite — the minerals making up seashells — also form non-biologically in the ocean.

In their study, the authors used the vast global fossil record of marine organisms that secreted calcium carbonate, which encompasses more than 400,000 samples dating from 10,000 years BC up to around 500 million years ago.

Using reconstructions of the temperature and the ocean water composition of the past, the authors estimated the proportion of aragonite and calcite that formed inorganically in the ocean in 85 geological stages across 500 million years.

Through a series of specially developed statistical analyses, this inorganic pattern of aragonite-calcite seas was then compared with seashell mineral composition over the same time.

The results show that up until the middle of the Jurassic period, around 170 million years ago, the ecological success of shell-secreting marine organisms was tightly coupled to their shell composition: organisms that secreted the mineral that was environmentally favoured had an evolutionary advantage.

However, the Earth-Life system was revolutionised forever by the rise of calcifying plankton, which expanded the production of calcium carbonate from continental shelves to the open ocean.

This ensured that the evolutionary impact of episodes of severe climate changes, and resulting ocean acidification, was less severe than comparable events earlier in Earth history.

Dr Uwe Balthasar, Lecturer in Palaeontology, first published research exploring the dominance of aragonite and calcite in the marine environment in 2015. He said: “During the Earth’s history there have been several major events that shaped the evolution of life on our planet, such as the five big mass extinctions or the radiation of complex animals during the ‘Cambrian Explosion’. Our research identifies a previously overlooked event of this magnitude around 170 million years ago when the emergence of calcium carbonate-secreting plankton lifted constraints on the evolution of other marine organisms that we did not know existed. As a result, life in the ocean has diversified to levels far beyond what existed before.”

Story Source:

Materials provided by University of PlymouthNote: Content may be edited for style and length.


Journal Reference:

  1. Kilian Eichenseer, Uwe Balthasar, Christopher W. Smart, Julian Stander, Kristian A. Haaga, Wolfgang Kiessling. Jurassic shift from abiotic to biotic control on marine ecological successNature Geoscience, 2019; DOI: 10.1038/s41561-019-0392-9

Cite This Page:

University of Plymouth. “Evolution of life in the ocean changed 170 million years ago.” ScienceDaily. ScienceDaily, 1 July 2019. <www.sciencedaily.com/releases/2019/07/190701143804.htm>.

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Author

Dursun Yıldız

dursun.yildiz@hidropolitikakademi.org

Civil Engineer-Expert on Hydropolitics

He was born in Samsun in 1958. He was graduated from İstanbul Technical University Civil Engineering Faculty in 1981. After completing his military service in 1983 he began to work in State Hydraulic Works Technical Research and Quality Control Department. While working here he participated graduate professional education and investigation programs in Holland and USA Bureu of Reclamation and US Army Corps of Engineers.

In 1998 he participated first “EU Master Education” program and later “International Affairs Proficiency” program in Ankara University European Union Research and Application Center. In 2000 he completed his MS thesis in the topic of water politics in Hacettepe University Hydropolitics and Strategy Research Center.
He worked for five years as the section head and for following 10 years as department deputy Director in State Hydraulic Works Technical Research and Quality Control Department. During this period he published more than 100 technical and scientific reports and papers. Then he worked as the department Deputy Director in State Hydraulic Works Domestic Water Supply Department and worked at the Planning and Investigation Department of the same institution and retired in 2007.

Dursun YILDIZ while working in State Hydraulic Works he lectured in the topics of water works in Gazi University Engineering and Architectural Faculty, Civil Engineering Department and water resources and hydropolitics in Hacettepe University, Hydropolitics and Strategy Research Center.

Dursun YILDIZ worked also as a executive committee member , Vice President in Chamber of Civil Engineers and Vice President of Union of Chambers of Turkish Engineers and Architects .

Dursun YILDIZ, experienced in water,hydro energy management and consultancy for 25 years, wrote ten books and besides published several papers and technical reports in the topics of water engineering and hydroenergy in national and international periodicals.
He has awarded Successful Water Resarcher Prize of Year of 2008 by Agriculturers Associations of Türkiye .

He is a member of Scientific Commitee of Turkish Foundation for Combating Soil Erosion (TEMA).

He is a member of Water-Soil-Energy Working Group that has followed development of water,soil and energy sectors since 2009. He is head of Ada Hydro-Energy , Strategy & Engineering Consultancy Co. Since 2007