Chapter 8: The Conservation of Aquatic Systems Flashcards
Compared to air, water has a higher ____. It can absorb and store large quantities of heat with relatively little change in temperature. This makes aquatic environments more stable in temperature than terrestrial environments, and their biotic communities less well adapted to rapid temperature changes
heat capacity
The greater density of water, compared to air, affects
transmission of light. As light passes through water, it
changes in wavelength and weakens in intensity. Such
changes create a ___ in which light penetrates to some maximum depth, determined in part by the relative clarity of the water.
photic zone
in aquatic environments like lakes, a ____ of high light intensity (more shallow water) dominated by the process of photosynthesis. Below this is a ____ of lower light intensity in which the dominant process is
decomposition.
trophogenic zone
tropholytic zone
Freshwater ecosystems:
1. like lakes and ponds, in which there is less internal movement of water, and therefore where zonation and stratification are more pronounced.
- like rivers and streams where water is constantly flowing. Such
ongoing movement of water in streams makes them more
resistant to physical stratifications.
Lentic systems
Lotic systems
the stream increases in magnitude or ___
stream order
Threats to Freshwater Ecosystems
Overexploitation
Water pollution
Flow modification
Species Invasion
Habitat degradation
occurs when nutrients are released into aquatic systems from upstream or surrounding agricultural areas (in the form of fertilizer runoff) or from towns and cities
Eutrophication
is a process through which the pH of surface freshwaters declines (becomes more acidic) because of inputs of acidic precipitation in the form of rain, snow, or fog.
Acidification
____ or pollution can take many forms in lakes and streams, but two of the most common are eutrophication and acidification
Chemical alteration
_____pose a greater threat in
aquatic habitats than terrestrial ones.
Introductions of exotic species
Because streamflow is the “master variable” limiting distribution of riverine species and regulating ecological integrity of flowing water systems, human-caused flow modification or ____ is, as we have already noted one of the most dangerous threats to freshwater species worldwide. Such alteration most commonly occurs as a result of building dams to create artificial impoundments of water.
alteration of flow regimes
But dams have even more devastating impacts on populations of____ which move from fresh water to salt water in their normal life cycle.
diadromous fish species
Dams are but one threat to the ___ of riverine aquatic ecosystems, defined as “water-mediated
transport of matter, or organisms within or between elements
of the hydrologic cycle”
hydrologic connectivity
Management for Freshwater Habitats:
Because problems like sedimentation, eutrophication and
acidification are input-driven, their solution lies in ___
Remedies for this problem are ___ (3)
input regulation.
dredging, chemical manipulation, and biomanipulation.
directly removes sediment from a lake, pond, or wetland, usually by physically scraping it off the bottom with large, earth-moving machines.
Dredging
attacks the eutrophication problem by altering the biotic community. First, densities of zooplanktivorous fish (usually the cyprinids) are reduced, either by
adding piscivorous (fish-eating) species or by extracting the
cyprinids directly by trawling with gill nets. If the number of
zooplanktivorous fish decline, zooplankton populations
should increase and the grazing rate on algae and phytoplankton will rise.
Bio-manipulation
Today aquatic habitat conservationists are increasingly
employing a strategy in the design and management of freshwater protected areas known as ____. This assumes the validity of the “landscape filter” model , a theory of aquatic community structure that sees freshwater aquatic
ecosystems, particularly rivers and streams, as products of
terrestrial environmental constraints or “filters” which control inputs of abiotic and biotic inputs to the stream ecosystem.
Whole catchment management or WCM
consists of a central, well-protected core surrounded by a series of buffer zones in which varying amounts of human activity are permitted. When it is not possible to protect an entire catchment, one alternative is to apply the
Multiple-Use Module (MUM)
A Four-tiered Approach
to Aquatic Conservation (TNC)
- aquatic zoogeographic unit
- ecological drainage units
- aquatic ecological systems
- macrohabitat
have been defined as lands transitional between terrestrial and aquatic systems where the water table is at or near the surface or the land is covered by
shallow water
Wetlands
Wetlands are unique in their ___- their characteristics of presence,
abundance, and sources or water. Hydrology interacts with
their second and third distinctive characteristics – their physico-chemical environment (geography, geology, and soil characteristics) and their unique biota (distinctive species of plants and animals).
hydrology
The year-round presence and abundance of all types of
wetlands not only maintains their unique ecological structure
and function but drives the second of their most distinctive
characteristics – the formation of ____. Due in part to their water-logged soils, wetlands are distinctive in their abundance of ____ (literally, “waterloving”) vegetation.
hydric (water-logged) soils.
hydrophytic
What is benthic environments?
ecological regions at the bottom of water bodies, such as oceans, seas, lakes, or rivers. This includes the sediment surface and sub-surface layers, where various organisms live, including bacteria, fungi, worms, crustaceans, and bottom-dwelling fish.
a keystone species that provides foundational habitat for multiple species of marine species, both vertebrate and invertebrate, especially in shallow water areas
Seagrass
One of the major threat to corals- is a response that occurs in temperature-stressed corals. When this occurs, there is loss of endosymbiotic dinoflagellates (zooxanthellae) living within the coral polyp that occurs as part of the coral’s stress response to temperature
bleaching
Destruction of coral reefs also occurs through ____, a form of direct destruction of coral reefs in which explosives are used to harvest fish from the reef. A single
blast can devastate thousands of cubic meters of coral reef,
destroying not only individual fish but the structure upon
which the community depends.
blast-fishing
Threats posed to marine ecosystems do not arise merely from overexploitation of targeted commercial species, but also
from mortality of non-target species which suffer as a result
of commercial fishing operations. In some fisheries, such as
shrimp, worldwide discarded biomass of non-targeted species exceeds the targeted catch. By far the most dangerous and pervasive threat of all to larger marine
vertebrates occurs “accidentally,” an insidious form of “unintended” mortality known as ___.
Bycatch
Areas closed to all types of marine fishing and harvesting. These are designed to protect a particular commercial stock or group of stocks from over-exploitation. At large scales, some “biosphere reserves,” administered by the
United Nations’ Educational, Scientific, and Cultural Organization (UNESCO), include marine reserves, like the
Palawan
Harvest refugia or no-take zones.
Is a conservation strategy
that attempts to simultaneously address biological, cultural,
economic, and political concerns through collaboration and
integration in conservation efforts between local
communities and government authorities.
Co-management
marine habitats that cover __of the earth’s surface and more than __ of its livable volume
71%, 90%
