Download Fundamental Nearshore Ecosystem Processes

Nearshore Processes
Definition1
We define ecosystem processes as any interaction among physiochemical and biological
attributes of an ecosystem that involve changes in character or “state” of the ecosystem
and its components.
These changes involve composition and quantity, as well as reorganization (movement)
of materials. Processes operate at various spatial and temporal scales, and have inherent
variability over different scales; variability can be very predictable, such as the cycles of
the tide, or stochastic, such as freshwater flood events.
These nearshore processes are all accommodated to some degree in the NST Conceptual
Model, and the interactions among processes (see aggregate processes, below)
specifically captured in the Conceptual Model’s Level 3 Scenarios.
Fundamental Nearshore Ecosystem Processes
All ecosystems are characterized by fundamental processes, most of which are involved
to some degree in promoting the structure and functions of nearshore ecosystems such as
found in Puget Sound. Thus, the relative importance of these nearshore ecosystem
processes depends extensively upon the nearshore setting and the functions being
considered. Definitions and brief examples of the most obvious and consequential
processes are:
1. atmospheric and climatic
a. deposition of precipitation in various forms and accompanying dissolved
and particulate matter, including contaminants
b. light, heat and force energy, involving sunlight radiance and forces applied
by winds and other atmospheric forcing
2. tectonic
a. earthquake—changes produced by large-scale deformations in the earth’s
crust, such as subsidence and uplifting caused by earthquakes
b. volcanic—production of particulate, gaseous and dissolved material from
volcanic eruptions that intercepts nearshore nearshore (involving hydraulic
processes when routed through watersheds and atmospheric processes
when deposited with precipitation)
3. hydrology
1
Where possible, definitions were selected to conform to scientific lexicons, based on Lincoln et al. (1985;
A dictionary of Ecology, Evolution and Systematics, Cambridge Univ. Press), Collin (1988; Dictionary of
Ecology and the Environment, Peter Collin Publ.) and American Geological Institute (1976; Distionary of
Geological Terms, Anchor Press).
a. tidal—rise and fall of tides, incorporating neap-spring variability and the
influence of freshwater inflow
b. freshwater—precipitation, point and groundwater inflow, and the
influence of lateral freshwater plumes in nearshore water column
c. wave—energy transmitted from waves intercepting the shoreline
4. sedimentological/geomorphological
a. erosion—removal of sediments and mineral particulate material by water,
wind and other forces, such as removal of sand from a barrier spit by
storm waves
b. accretion—deposition of sediments and mineral particulate matter, such as
the building and maintaining of salt marsh surface by settlement of
suspended particular matter from the water flooding the marsh
c. transport—movement of sediments and other matter, including organic
and dissolved matter, carried by water and wind, such as long-shore
transport of sediments by waves and currents
5. nutrient transformation and translocation
a. dissolved organic to particulate organic—conversion of dissolved organic
matter to particulate matter by physical (e.g., flocculation) or biochemical
(e.g., uptake by organisms) processes
b. inorganic to organic form—conversion of inorganic nutrients into organic
(e.g., uptake of N2 gas by plants and incorporation into the organic
structure of the plant), which is a critical process of plant photosynthesis
c. inorganic species change—changes in inorganic nutrient states and species
(e.g., nitrification, involving oxidation of ammonium nitrogen to nitrate or
nitrite in aerobic environments, or volatilization, where ammonium in
sediments is converted to ammonia and released to the atmosphere
6. primary production and reproduction
a. assimilation of organic matter by plants (autotrophs)—the process of
photosynthesis
b. production of seeds and other propagules—maintaining vegetation and
providing sources of recolonization
7. food web—involving the transfer of organic matter, from production through
consumption, through increasing trophic levels of organisms in a community
a. primary consumption—eating of living plant material, by herbivorious
animals
b. excretion and respiration—loss of organic matter and energy through
release of heat and gases in respiration and of organic waste matter
c. decomposition and detritus consumption—physicochemical and biological
reduction of non-living organic matter and reincorporation into living
organisms
d. secondary and tertiary production—accumulation of organic matter by
animals consuming other animals
i. consumption—animals eating other animals
ii. growth—incorporation of organic matter into an organisms tissues
iii. reproduction—production of offspring by an organism
8. ecological
recruitment—appearance of offspring within the ecosystem, from both
internal and external sources
predation—consumption processes (see 7. food web) affecting the biological
structure of an ecosystem and its component communities by influencing the
strength of key food web, competition and other linkages
competition—competitive interactions among organisms
symbiosis—mutualistic and other interactions between two organism living
together, including intraspecific associations; can include detrimental
interactions (e.g., parasitism) or mutually beneficial interactions (i.e.,
mutualism)
Aggregate Processes
These discrete processes interact in aggregate to comprise what might be considered
“metaprocesses” that develop and maintain nearshore ecosystems. For instance, the
migration of nearshore lagoon barriers involves the net effect of erosion, accretion and
sedimentary processes driven by wind, wave and tidal current energy that influences the
transport of sediments into, away from and within the barrier region. The spatial and
temporal variability of barrier movement depends upon the frequency, intensity and
duration of the climatic events that initiate these processes.
Similarly, food web structure and support of important nearshore organisms involves the
highly complex interaction of internal and external (e.g., watershed) processes that make
primary-produced and detrital organic matter available to consumers in nearshore
ecosystems, in addition to primary and detrital bases of food webs originating directly
within nearshore ecosystems.