1
Q
P/R Ratio
A
Primary Productivity to respiration ration (P/R<1 shredders/collectors, P/R>1 collectors/grazers, P/R<1 collectors/predators)
2
Q
Detrital energy
A
Allochthonous: Leaf/litter, soil particulates, compounds dissolved in soil water
Autochthonous: dying macrophytes, animal carcasses and feces, extracellular release of dissolved compounds
3
Q
Pros of using biotic data
A
Snapshot vs longterm data, shows effects that are hard to measure, cheaper, tangible data
4
Q
IBI
A
Index of Biological Integrity, main categories: species composition, trophic composition, fish abundance and condition
5
Q
Human-induced alterations, BIOTIC INTERACTIONS
A
- increased frequency of diseased fish
- altered primary and secondary production
- altered trophic structure
- altered decomposition rates and timing
- disruption of seasonal rhythms
- shits in series composition and relative abundances
- shifts in invertebrate functional groups
- shift in trophic guilds
- increased frequency of fish hybridization
6
Q
Human-induced alterations, FLOW REGIME
A
- altered flow extremes
- increased max flow velocity
- decreased min flow velocity
- reduced diversity of microhabitat velocities
- fewer protected sites
7
Q
Human-induced alterations, HABITAT QUALITY
A
- decreased stability of substrate and banks due to erosion and sedimentation
- more uniform water depth
- reduced habitat heterogeneity
- decreased channel sinuosity
- reduced habitat area
- decreased instream cover and riparian vegetation
8
Q
Human-induced alterations, WATER QUALITY
A
- expanded temperature extremes
- increased turbidity
- altered diurnal cycle of DO
- increased nutrients
- increased suspended solids
9
Q
Human-induced alterations, ENERGY SOURCE
A
- decreased coarse particulate OM
- increased fine particulate OM
- increased algal pollution
10
Q
Threats to cold water steam fishes
A
- Introduced species (competition and introgression)
management option: population management (isolation/removal) - Habitat degradation (temperature and dams)
management option: best management practices (buffers, channel improvements, dam removal) - Climate change
management option: creation of refugia
11
Q
Coldwater streams
A
- max summer T: 22°C
- flowing waters, typically low order streams
12
Q
What affects stream temperatures
A
- air-water surface exchange
- stream discharge
- ground water/hyporheic exchange
- topography
- shading
- small impoundments act like lakes, warmer in fall and winter but colder in spring and summer than surrounding streams
13
Q
Xylophagous
A
Feeding or boring into wood
- presence of wood substantially increases the number of taxa at a site
- wood makes up a small % of habitat but contributes to a lot of biomass
14
Q
Macrophytes
A
Aquatic plants growing in or near the surface
- provide structural complexity
- support more abundant and richer communities of invertebrates
- periphyton: complex mixture of algae, cyanobacteria, heterotrophic microbes, and detritus
15
Q
Fine particles
A
< 1-2 mm
cause a decline in tot abundance and taxonomic richness (EPT taxa particularly sensitive)
16
Q
Taxon diversity
A
structural complexity and heterogeneity are considered to influence both individual abundance and taxon richness
17
Q
Niche theory
A
Describes how an organism or population responds to the distribution of resources and competitors ( Biotic vs Abiotic vs Movement/Dispersal limitations)
18
Q
Why flow rate is a master variable?
A
it affects channel slope, substrate composition, flow preferences, and spawning cues
19
Q
Types of flows
A
Laminar: fluid particle movement is regular and smooth
Turbulent: irregular movement of water, unpredictable and dissipative
Transitional: intermediate conditions
20
Q
Ecological processes affected by flow
A
- Dispersal
- Habitat use
- Resource aquisition
- Competition
- Predator-prey interactions
21
Q
Key abiotic features
A
- current
- substrate
- temperature
- water chemistry
- DO
- alkalinity
- physical habitat
22
Q
Bankfull flow
A
Flow that fills the channel up to the top of banks prior to flooding
23
Q
Thalweg
A
Deepest, fastest part of a stream channel
24
Q
Sinuosity
A
Length of stream channel / length of straight line distance
25
Colluvium
Loose, heterogeneous, and incoherent mass of soil material and/or rock fragments deposited by rainwash
26
Alluvium
Deposit of clay, silt, sand, and gravel left by flowing streams in a river valley or delta
27
Alkalinity
It's the buffering capacity of a water system (limestone makes streams more basic)
28
Factors affecting stream pH
- natural rain water pH 5.7
- soil buffering capacity
- organic acids
- sulfur/soda springs
- pollution
29
DO
Dissolved Oxygen
Hypoxic: DO < 2 mg/l
Anoxic: DO 0 mg/l
30
Major components of streamwater chemistry
- suspended inorganic matter
- gases (N2, CO2, O2)
- dissolved ions (Ca, HCO3)
- dissolved nutrients (N, P)
- organic matter
- trace metals
31
Urban watershed
- impervious surfaces
- rapid runoff
- flashy streams, peak discharge has a short duration
32
Forested watershed
- soil can store more water
- infiltration processes dominate
- lower magnitude, long duration
33
Vadose zone
Water between soil surface and top of the water table
34
Natural Flow Regime components
1. Magnitude
2. Frequency
3. Duration
4. Timing
5. Rate of change
Modification of flow has a cascading effect on the ecological integrity of rivers
35
Hydrologic alteration
- dams
- diversion weirs
- water abstraction
36
Perennial vs Ephemeral stream
Perennial: continuous flow during the entire year
Ephemeral: flowing only during wet periods
37
Fluvial geomorphology
The study of channel forms and the processes and interactions among channel, floodplain, river network, and catchment
38
Convergent evolution
Processes in which organisms that are not closely related independently evolve similar features
e.g. Dr. Stiassny studying blind fishes in the Congo River
39
Factos affecting hydrographs
- dams / releases
- riparian zone in good vs poor condition
- presence vs absence of parking lots / impervious surfaces
- evapotranspiration
- channelization
40
Hyporheic zone
Is the region of sediment and porous space beneath and alongside a stream bed, where there is mixing of shallow groundwater and surface water
41
Highest velocities in streams
They are found where friction is least, generally at or near the surface and near the center of the channel
42
Discharge
Volume of water/flow moving past a point over some time interval
43
Degradation
Erosion, or removal of sediment in a river. Kinetic energy increases and the sediment is not able to settle out
44
Aggradation
The deposition of material by a river, stream, or current
45
Advection
Unidirectional force of current
46
Ecosystem engineer
A species that significantly modifies habitat, often influencing habitat heterogeneity and species diversity
47
Natural bank and bed erosion
- promotes riparian vegetation succession
- creates habitats for aquatic plants and animals
- above ground biomass of plants modifies flows and retains sediment
- below ground biomass affects soil moisture and susceptibility to erosion
48
Floodplain
Is a generally flat area of land next to a river or stream. It stretches from the banks of the river to the outer edges of the valley
49
Serial Discontinuity Concept
Theoretical construct that views impoundments as major disruptions of longitudinal resource gradients along river courses
50
Natural Flow Regime Paradigm
Naturally occurring temporal fluctuations in streamflow are necessary for maintaining natural ecological communities
51
4 Dimensions of Streams
1. Longitudinal (upstream-downstream)
2. Lateral (Riparian/floodplain)
3. Vertical (Hyporheic zone)
4. Temporal (response time following disturbance)
52
Primary producers
Macrophytes, Periphyton, and Phytoplankton
Functions:
- nutrient uptake
- biomass
- pollutant sink
- photosynthesis and respiration
53
Aufwuchs
mosaic of periphyton and heterotrophic organisms
53
Major algae groups
Cyanobacteria, Diatoms (most abundant in the US rivers), and Green algae
54
Temporal and Spatial Variability
Temporal:
- frequent disturbance results in low but constant biomass
- less frequent disturbance results in cycles of accumulation and loss
Seasonal Variation:
- temperate locations are dominated by diatoms
- biomass is highest in spring, followed by fall
Spatial:
- habitat, landscape position, and climate
55
Phytoplankton distribution
- higher discharge, lower abundance
- higher turbidity, lower productivity
- higher light availability, higher productivity
- higher grazing, lower phytoplankton abundance
- higher nutrients, higher productivity
56
Factors driving fish diversity
1. Age
2. Depth
3. Adaptations for dispersal
4. Continental drift
5. Species invasions
6. Location
7. Anthropogenic impacts
57
Species area relationship
There should be more species the larger the area that's sampled (species richness highest in South America and lowest in Europe)
58
Congo River Case Study
Hydraulic complexity as a driver of fish diversity
59
Diadromous
fish migrating between fresh and marine ecosystems
60
Anadromous
fish migrating from oceans to rivers
61
Catadromous
fish migrating from rivers to oceans
62
Amphidromous
fish migrating from fresh to salt water at some point other than breeding
63
Potadromous
migrates within freshwater habitats
64
Common Fish Families
1. Leuciscidae
2. Centrarchidae
3. Catostomidae
4. Percidae
5. Ictaluridae
6. Moronidae (White Bass)
65
Functional Feeding Groups
- Shredders (CPOM)
- Collectors/Gatherers (fine benthic OM/ FPOM)
- Collectors/Filterers (FPOM)
- Scrapers (biofilms)
- Predators (other insects)
66
What affects macroinvertebrate abundance?
1. Flow regime
2. Stream location
3. Pollutants/human activities
67
Key Macroinvertebrate orders
- Odonata (dragonflies, damselflies)
- Plecoptera (stoneflies)
- Ephemeroptera (mayflies)
- Trichoptera (caddisflies)
- Megaloptera (hellgrammites)
68
Contribution of macros in the nutrient cycling
They ingest a large portion of the available nitrogen
69
Major factors that determine the presence and abundance of a hyporheic fauna
hydraulic permeability
70
Groundwater - macro
Insects are poorly represented in true groundwater habitats; presumably due to their dependence on access to the surface for one or more stages of their life
e.g. Edwards Aquifer, Stygobitic dytiscids
71
What is drift?
Downstream transport of stream insects/other invertebrates in stream currents
72
Why do organisms drift?
- on of the major factors is food limitation
- recolonization after disturbance
- variables affecting drift also include water depth, velocity, and settling time
73
Drift categories
1. Catastrophic: results from disturbance of the benthos
2. Constant: continual drift of low numbers of most species of stream insects
3. Behavioral: indicated by characteristic patterns of behavior resulting in a predictable diel periodicity
74
What type of macros are more likely to drift?
Ephemeroptera, Simuliidae, Plecoptera, and Trichoptera are the most common
75
Drift Cues
- Photoperiod
- Current velocity/discharge (increased shear stress results in substrate removal)
- water chemistry/temperature (low DO causes species to move)
- benthic density
- predators
- life cycle stages
- catastrophic (flooding, sedimentation, fish spawning)
76
Stream Drift Paradox
In streams, a long-standing question, dubbed 'the drift paradox', asks why aquatic insects faced with downstream drift are able to persist in upper stream reaches
77
Dispersal
Main mechanism that drives geneflow within and between populations
78
Key concepts related to drift
- alters distribution and colonization
- alters energy flow
79
Nutrient Spiraling Hypothesis
- Webster and Pattern 1979, pointed out that nutrients in stream don't cycle in place, but are displaced downstream as they complete the cycle
- N and P cycling are a cornerstone of ecosystem biogeochemistry because all biota depend on these elements for critical cellular processes
80
Assumptions for the Serial Discontinuity Concept
- RCC and Nutrient Spiraling Hypothesis are true
- the watershed is free of pollution and impoundments
- undisturbed lotic reaches (riparian zones)
- impoundment releases are not hyporheic and thermally stratified
81
Serial Discontinuity Concept
Views impoundments as major disruptions of longitudinal resource gradients along river courses
82
Flood Pulse Concept
- Littoral zone, lateral dimension is more important for biota than longitudinal dimension
83
Fish Life-History Strategies:
Fish Life-History Strategies: periodic (Sturgeon), opportunistic (Killifish), and equilibrium (Blue gill) spawners
84
Fish assemblage responses
- IBI estimates changes in the health of a fish community
- assessment of changes in taxonomic distribution
- changes in recruitment assessed through functional groups, feeding classes, reproductive guilds, and habitat guilds
85
Species interactions
- predation +/-
- competition -/-
- commensalism +/0
- mutualism +/+
- amensalism -/0
- neutralism 0/0
86
Definition of Keystone species
keystone species help to keep an ecosystem together and functioning by shaping it in various ways, from being apex predators to ecosystem engineer
e.g. Serengeti Rules, Mary Power
87
Trophic cascades
It's an ecological phenomenon triggered by the addition or removal of top predators and involving reciprocal changes in the relative populations of predator and prey through a food chain, which often results in dramatic changes in ecosystem structure and nutrient cycling.
88
Herbivory
Consumption of autotrophic basal resources in lotic food webs (primary producers such as algae, cyanobacteria, bryophytes, vascular plants)
89
Bottom-up effects
Higher productivity driven by nutrient enrichment potentially can propagate along food chains, increasing productivity of consumers and possibly lengthening food chains by supporting the addition of another trophic level
90
Herbivory basal resources
N and P content are key predictors of bottom-up effects
91
Top-down effects
predators typically reduce abundance of their prey, which benefits the next trophic level down the food chain. This pattern is widely observed when predators reduce grazers, leading to an increase of algae. When the effect extends over multiple trophic levels it's called *trophic cascade*
92
Effects of grazers on ecosystem processes
- impact on gross primary productivity
- downstream transport of carbon
- nutrient cycling
- plant abundance and composition
- modify habitats
93
Why does predation fall more intensively on some individuals or species relative to others?
1. Predator choice, preference for a specific prey
2. Prey vulnerability, product of size/body plan, palatability/energy content, life style/habitat preferences
94
Prey detection
- Vision
- Hearing
- Pressure/current detection
- Chemoreception
- Electroreception
95
Primary factors influencing selectivity of prey items
1. Abundance
2. Size
3. Motion
4. Contrasting coloration/body plan
96
Learned/Acquired Specialization
Predator behavior changes in relation to experience, tendency arises to forage on prey items which the predator consumes most frequently, with energetically-driven preferences
97
Prey detection
Happens primarily by mechanical means
Two common tactics:
- sit and wait/ambush
- actively searching stream bottoms
98
Primary factors affecting foraging of aquatic macroinvertebrates
- light <0.1 is a common threshold for visual cues
- increased habitat heterogeneity may increase prey availability but may also decrease foraging efficiency
- predation rates increase with increasing temperature
99
Optimal Foraging Theory
Optimal foraging theory states that natural selection favors foraging strategies that balance the benefits of a particular food, such as energy and nutrients, with the costs of obtaining it, such as energy expenditure and the risk of predation. Optimal foraging maximizes benefits while minimizing costs
100
Trophic level
position an organism occupies in food cain
101
Trophic structure
Pathways by which energy is transferred
102
Properties of Trophic Interactions
Only a portion of the energy of one trophic level is available for transfer and use by higher trophic levels
103
What limits the number of trophic levels in an ecosystem?
Loss of energy at each trophic level is the reason which limits the number of trophic levels in a food chain
104
What are some stream characteristics that could impact the trophic makeup of an ecosystem?
- physical template (fluvial geomorphology)
- hydrology
- climate
- land use
- drainage/watershed position
105
Connectivity in streams
High degree of connectivity between stream-riparian zones and surrounding ecosystems are derived from position in valley bottoms and its elongated form, which leads to high ratio of edge length to core area
106
Riverine Landscapes
A riverine landscape includes the ecosystems (all living things including plants and animals) in and around the area of a river. A riverine may also be defined as a network of rivers and the surrounding land
107
ICI
Invertebrate Community Index
108
Why measure stream metabolism?
Measuring stream metabolic state is important to understand how disturbance may change the available primary productivity, and whether and how that increase or decrease in NEP influences foodweb dynamics, allochthonous/autochthonous pathways, and trophic interactions
Stream ecosystem metabolism is concerned with quantifying the balance of production and respiration
109
Gross primary production (GPP)
Total amount of new C fixed
110
Net primary production (NPP)
Total amount of new C minus autotrophic respiration
111
Net ecosystem production (NEP)
Total amount of new C, minus total respiration (autotrophs + heterotrophs)
112
Different P/R among streams
- most streams tend to be net heterotrophic (P/R < 1)
- some can have (P/R > 1)
e.g. desert streams
113
Drivers of stream metabolism
- region characteristics
- land use
- OM
- hydrology
- nutrients
- light
114
Forest vs desert streams OM budgets
forest: GPP 3.5, CBOM 610
desert: GPP 1888, CBOM 5.2
115
Seasonal patterns of C turnover
Streams can be more efficient in early/late summer in terms of C turnover
116
Stream ecosystem metabolism
- Stream metabolism: measures DO to quantify GPP, Ecosystem Respiration (ER), and the relative importance of each
- Organic matter budgets: quantify all inputs, standing stocks and outputs of OM in a reach
- Stream ecosystem efficiency: measure of carbon/organic matter turnover time and length and gives an ecosystem scale view of OM processing and C retention in streams
117
Ecosystem Services
1. Provisioning services: include the production of directly consumed resources, such as fish, drinking water, and hydropower
2. Regulating services: are the benefits obtained from regulating processes, including waste decomposition and water purification, flood control, and pest suppression
3. Supporting services: include basal resources, nutrient and other biogeochemical cycles, degradation of organic wastes, and species habitat
4. Cultural services: include educational, recreational, aesthetic, and spiritual benefits
118
Rheophilia
Love for nature broadly, and for rivers specifically
119
Goals in River Management
Restoration, Rehabilitation, and Improvement
120
Integrated River Basin Management
Integrated river basin management (IRBM) is the process of coordinating conservation, management and development of water, land and related resources across sectors within a given river basin, in order to maximise the economic and social benefits derived from water resources in an equitable manner while preserving and, where necessary, restoring freshwater ecosystems
121
Ecosystem-based management
Advocates a holistic approach that recognizes the full array of interactions within an ecosystem, including people and their activities, and the need for cooperative management over large jurisdictional areas
122
Adaptive management
It's an integrated, interdisciplinary approach that emphasizes on-going cycles of learning through management interventions, whether they succeed or fail, and the harmonizing of environmental and societal goals as the guiding framework
123
EPA
The Environmental Protection Agency (EPA) creates and enforces laws designed to protect the environment and human health
124
Major acts
- Endangered Species Act
- National Environmental Policy Act
- Wild and Scenic Rivers Act
- Surface Mining control and Reclamation Act
- Clean Water Act
125
US Clean Water Act (CWA)
In effect since 1972, enforces the total maximum daily load (TMDL) for all pollutants identified as causing impairment
126
Three Pillars of River Management
1. Fundamental science
2. Measurement of progress
3. Societal support
127
Proximate causes of ecosystem changes
- urbanization
- industry/mining
- land use/agriculture
- watercourse alterations
128
Ultimate forcing factors of ecosystem changes
- ecosystem destruction
- physical habitat alteration
- water chemistry
- direct species additions/removals
129
Freshwater biodiversity components
- overexploitation
- flow modification
- water pollution
- habitat degradation
- species invasions
130
Inland waters values
- economic
- cultural
- aesthetic
- scientific
- educational
STREAM ECOLOGY
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