![]() Grouping these ecosystems into just a few biome categories obscures the great diversity of the individual ecosystems within them. Terrestrial ecosystems, also known for their diversity, are grouped into large categories called biomes, such as tropical rain forests, savannas, deserts, coniferous forests, deciduous forests, and tundra. ![]() Lakes, rivers, streams, and springs comprise these systems they are quite diverse, and they support a variety of fish, amphibians, reptiles, insects, phytoplankton, fungi, and bacteria. Such ecosystems exist even at the bottom of the ocean where light is unable to penetrate through the water.įreshwater ecosystems are the rarest, occurring on only 1.8 percent of the Earth’s surface. Although not as diverse as the other two, deep ocean ecosystems contain a wide variety of marine organisms. These two environments are especially important to aerobic respirators worldwide as the phytoplankton perform 40 percent of all photosynthesis on Earth. The shallow ocean ecosystems include extremely biodiverse coral reef ecosystems, and the deep ocean surface is known for its large numbers of plankton and krill (small crustaceans) that support it. Ocean ecosystems are the most common, comprising 75 percent of the Earth’s surface and consisting of three basic types: shallow ocean, deep ocean water, and deep ocean surfaces (the low depth areas of the deep oceans). Within these broad categories are individual ecosystem types based on the organisms present and the type of environmental habitat. There are three broad categories of ecosystems based on their general environment: freshwater, ocean water, and terrestrial. (credit a: modification of work by “takomabibelot”/Flickr credit b: modification of work by Ivan Mlinaric) Ecosystems can be small, such as the tide pools found near the rocky shores of many oceans, or large, such as the Amazon Rainforest in Brazil (Figure 1).įigure 1: A (a) tidal pool ecosystem in Matinicus Island in Maine is a small ecosystem, while the (b) Amazon Rainforest in Brazil is a large ecosystem. These are all important environmental variables that determine which organisms can exist within a particular area.Īn ecosystem is a community of living organisms and their interactions with their abiotic (non-living) environment. Other critical factors influencing community dynamics are the components of its physical and geographic environment: a habitat’s latitude, amount of rainfall, topography (elevation), and available species. The resources for which organisms compete include organic material from living or previously living organisms, sunlight, and mineral nutrients, which provide the energy for living processes and the matter to make up organisms’ physical structures. Competition in communities (all living things within specific habitats) is observed both within species and among different species. These results suggest that the repeated introduction of pollutants could accelerate microbial succession in microcosms, resulting in the rapid re-equilibration of microbial communities.Ĭonditionally rare taxa environmental pollution microbial succession microcosm temporal dynamics.Life in an ecosystem is often about competition for limited resources, a characteristic of the theory of natural selection. ![]() In addition, conditionally rare taxa that were specific to the treatments exhibited higher betweenness centrality values in the co-occurrence network, indicating a strong influence on other interactions in the community. The rate of appearance for new taxa and the temporal turnover within microbial communities were higher than the rates reported in other studies of microbial communities in air, water and soil samples. Specifically, the repression and induction of microbial taxa were dominant, and the fluctuation was not significant. The dynamics of microbial communities in response to different pollutants alone and in combination displayed similar patterns during enrichment. Subculturing was performed at 10-day intervals, followed by high-throughput sequencing of 16S rRNA genes. To investigate the temporal dynamics of microbial communities in response to pollutants, we analysed the microbial community structure in batch microcosms that were inoculated with soil bacteria following exposure to individual or combined pollutants (phenanthrene, n-octadecane, phenanthrene + n-octadecane and phenanthrene + n-octadecane + CdCl 2 ). Given the increasing human pressure on the environment and natural resources, responses to the repeated introduction of organic and inorganic pollutants are of particular interest. ![]() Elucidating the mechanisms underlying microbial succession is a major goal of microbial ecology research.
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