Persistent Green Smelly Lakes
Low phytoplankton biomass, abundant macrophytes, high water transparency, and stable Daphnia populations are all characteristics of this alternative stable state in lakes.
What is oligotrophic state?
This stage in the invasion sequence involves species transported beyond native range by a human vector. Intentional examples include sport fish stocking, aquaculture, and the aquarium trade. Other unintentional examples include ballast water exchange, hull fouling and shipping canals associated with global shipping of goods.
What is Introduction
Aquatic insect drift is passive and unidirectional so upstream populations should go extinct. Yet upstream invertebrate populations persist. This is referred to as the _____________.
Cyanobacteria
This functional feeding group feeds on course particulate organic matter (leaves, twigs, detritus) and is more dominant in headwater streams (stream order 1-4).
What are shredders?
Reduced light penetration and macrophyte suppression due to high phytoplankton biomass, high internal phosphorus loading, and dominance of cyanobacteria are all feedback mechanisms that can limit recovery to a clear water state from this trophic state.
What is eutrophic lakes?
Self-sustaining reproducing populations outside of captivity indicate the ___________ phase of the invasion sequence has occured.
What is Establishment
Many taxa crawl upstream against stream flow. These movements increase in lower velocity areas and occur more at night.
What is rheotaxis?
Increased _____________ frequency and duration can alter dilution capacity and concentrate nutrients in lakes.
What is drought
What is heterotrophic?
A substantial change in the structure and processes of a complex system, such as an ecosystem, climate, or financial system, which leads to a new, persistent state is referred to as a _____________.
Regime shift
Increasing range and associated undesirable impacts including ecological (predation, competition, disease, etc) and/or economic (industrial fouling, fishery collapse, tourism loss, etc) indicate what final ________stage has happened.
What is Invasion
Production rates exceed drift rates of invertebrates.
What is excess production?
A consequence of climate change is less frequent but more intense rainfall events. This can lead to _____________
What is greater pulse loads of nutrients to lakes in shorter periods of time?
The ratio of course to fine particulate matter (CPOM/FPOM) increases with ____________ stream order.
What is decreasing?
This concept is depicted by an ecosystem that cannot be returned to the previous regime by simply returning to the same external conditions. For example a eutrophic lake may not return to a mesotrophic condition simply by preventing more nutrients from entering the lake.
What is hysteresis?
This fish is a popular dish in Asian culture. It's large size and fast growth rates (4-5 pounds in 1st year), high reproductive rate (females produce 597,000 to 4.3 million eggs per year, and diet (consume phytoplankton, algae and detritus) are all natural history traits that allowed for it to become a successful invader of midwestern streams in the U.S.
What is Asian carp
As local density increases, drift rate increases providing a negative feedback that redistributes resources to the remaining local population. This provides more resource per individual which can increase fitness and maintain the upstream population.
What is density-dependent drift regulation?
Warming temperatures extend the period of thermal _____________ in lakes.
What is stratification?
Mid-order streams (4-6) have less canopy cover which can lead to a more autotrophic (P/R >= 1) energy base. Under these conditions, this functional feeding group would exhibit a positive increase in relative abundance.
What is grazer?
Phosphorus and nitrogen that have accumulated in soil, groundwater, or lake sediments over decades due to previous fertilizer application, and continue to affect water quality or contribute to crop growth long after they were applied.
What are legacy nutrients?
The Asian Carp was introduced, became established, and has expanded its range across the Mississippi River Basin. This unintentional vector could lead to its expansion into the Great Lakes.
What are canals
Stable isotope evidence from mayflies in Alaska streams estimated between 1/3 to 1/2 of adult mayflies fly approximately 1613 m upstream to lay eggs (oviposit).
What is upstream adult flight dispersal?
Prolonged hypolimnetic anoxia as a consequence of extended thermal stratification, increases this biogeochemical process in lake sediments.
What is internal loading of phosphorus?
Shredders feeding on leaf material get most of their nutrition from ______________.
What are biofilms?