Early Aquatic and Terrestrial ecosystem.pptx

Basic info about the topic

1. Early Aquatic and Terrestrial ecosystem

2. Today’s ecosystems are amazing in the complexity of the interdependent relationships between the organisms that make up them. Energy and biomass circulate through food webs that unite bacteria, unicellular organisms, plants/algae and animals of extremely varied nature and size. The stability of these biological systems is based on dynamic balances that are nevertheless very sensitive to environmental and anthropogenic factors. 

3. Early Aquatic Ecosystem An aquatic ecosystem is an ecosystem in a body of water. Communities of organisms that are dependent on each other and on their environment live in aquatic ecosystems. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems. Early aquatic ecosystems were mostly marine ecosystem. Some water bodies like rivers and lakes were formed due to melting of glaciers .

4. For more than three billion years, marine ecosystems have been dominated by microbial organisms (bacteria, archaea) or unicellular eukaryotes. While these organisms have played a key role in the biogeochemical cycles of carbon or nitrogen and in raising the level of oxygen on our planet, they have never formed complex food webs as we know them in nature today . A little over 500 million years ago, the appearance of multicellular and macroscopic organisms at the end of the Precambrian and the advent of the animal kingdom during the Precambrian-Paleozoic transition revolutionized the marine world and its mode of operation. Early Aquatic Ecosystem

5. Early Terrestrial Ecosystem A community of organisms and their environment that occurs on the land masses of continents and islands. Terrestrial ecosystems are distinguished from aquatic ecosystems by the lower availability of water and the consequent importance of water as a limiting factor . Terrestrial ecosystems are characterized by greater temperature fluctuations on both a diurnal and seasonal basis than occur in aquatic ecosystems in similar climates. The availability of light is greater in terrestrial ecosystems than in aquatic ecosystems because the atmosphere is more transparent than water.

6. Gases are more available in terrestrial ecosystems than in aquatic ecosystems. Those gases include carbon dioxide that serves as a substrate for photosynthesis, oxygen that serves as a substrate in aerobic respiration, and nitrogen that serves as a substrate for nitrogen fixation. Terrestrial environments are segmented into a subterranean portion from which most water and ions are obtained, and an atmospheric portion from which gases are obtained and where the physical energy of light is transformed into the organic energy of carbon-carbon bonds through the process of photosynthesis. Early Terrestrial Ecosystem

7. The establishment of complex continental ecosystems is probably the most important event in the history of multicellular life after the Cambrian and Ordovician radiations that revolutionized the marine world and led to the formation of the first complex ecosystems. Plants were the first to colonize the mainland during the Ordovician, 470 million years ago, fundamentally changing the geosphere through oxygenation of the atmosphere, soil formation and the establishment of new climatic and sedimentary regimes. Early Terrestrial Ecosystem

8. Arthropods were the first animals to take the first steps on land along with myriapods (“centipedes”) and arachnids (spiders, scorpions, mites) at the end of the Silurian, 430 million years ago, then hexapods (insects) followed at the beginning of the Devonian (- 410 million years). Terrestrial vertebrates, tetrapods , only appeared in the middle of the Devonian (-380 million years ago), while the first complex terrestrial ecosystems, formed by highly diversified forest communities, were already well established. Early Terrestrial Ecosystem

9. First Vascular Plant The simplest and presumably most primitive vascular plants from the Late Silurian and Early Devonian periods (about 419.2 million to 393.3 million years ago) were the Rhyniopsida . They included plants such as Cooksonia and Rhynia , which were herbaceous colonizers of moist habitats. Most were less than 30 cm (12 inches) tall. The plant body was not differentiated into stems, leaves, and roots; rather, the forking aboveground axes bore terminal sporangia and produced stomata, which demonstrate that the plants were green and photosynthetic. Surface or underground axes served to root the plant and were anchored by rhizoids. Because such plants produced only one type of spore, they were nonseed plants with a homosporous life cycle and free-living gametophytes. A small number of such gametophytes have been described from Devonian deposits.

10. Cooksonia The now-extinct Cooksonia rose just a few centimeters above the ground, with branching stems capped by sporangia (showing it is a sporophyte) but without roots or leaves. In at least one of the five species, a dark stripe suggests the remnants of vascular tissue.

11. Cooksonia