Lake Communities & Phytoplankton

What is lacustrine?

meaning related to or associated with lakes.

What is riverine?

related to or associated with rivers or streams

What is lentic? What are examples?

inhabiting or situated in still, non-flowing freshwater systems

-Lake, pond, swamp, marsh, bog

What is lotic? What are examples?

inhabiting or situated in flowing freshwater systems

-River, stream, spring, brooks

What are the four zones in Lacustrine zonation?

littoral zone

limnetic zone

profundal

Benthic

What is the littoral zone?

open water and near the shore

What is the limnetic zone? What is another name for this zone?

open water.

-pelagic zone

What are the two main subdivision of the limentic zone?

Trophogenic (euphotic)

Tropholytic (Profundal)

What is the limnetic (pelagic) zone dominated by?

planktonic organisms

What are plankton?

they have limited locomotion, they cannot usually swim against minimal currents

What are phytoplankton?

photosynthetic algae, other autotrophic protists, cyanobacteria

What are examples of zooplankton of the limnetic zone?

heterotrophic protists, rotifers, microcrustaceans (copepods, cladocerans), insect and fish larvae

How do zooplankton disperse?

they are subject to dispersal via turbulence and other H2O movements

Are zooplankton the same density as water?

no, they are typically more dense than H2O so they tend to continually sink to greater depths unless they are resuspended.

What are nektonic organisms? What are examples?

they live in the limnetic zone.

-they are animals capable of swimming independently of turbulence

-Fish, certain zooplankton, insects and their larvae

The limnetic zone may also contain? What are they adapted to?

may also contain Neuston & Pleuston

-they are specially adapted to live at air/H2O interface

What are neuston? What are examples?

microscopic organisms that include bacteria, algae, and protists

What are pleuston? What are examples?

larger organism.

-water striders, duckweed, mosquito larvae

What is the benthic zone?

this refers to the bottom of freshwater (or marine) habitats

What are organisms that live in the benthic zone called?

benthos

-living in, on, or in association with the bottom.

What are Aufwuchs?

typically used for organisms that are attached to surfaces.

What is periphyton?

means attached microflora.

-adds specificity to the Aufwuchs organisms.

The benthic regions in lakes are divided into what four zones?

epilittoral

littoral zone

sublittoral

profundal zone

What is the epilittoral zone?

are above high water line and wave splash

What is the sublittoral zone?

scattered photosynthetic algae and cyanobacteria; no vascular macrophytes; may correspond to metalimnion

What is the profundal zone?

remainder of benthic area of lake; generally free of photosynthetic organisms (in tropholytic zone)

What are phytoplankton? What are they the key for?

they are autotrophs and important for ecological functions.

-they are the key for aquatic food webs. usually the base of the web (except in small-med rivers)

How important is the carbon cycle of phytoplankton?

VERY. it is 1/2 of global photosynthesis and O2 production but only 1% of plant biomass.

Do phytoplankton respond fast to climate changes?

they have high turnover rates (days) of community and they respond RAPIDLY on a global scale to climate variations.

How can so many taxa occupy plankton niche?

1 partial explanation is that they utilize different wavelengths of light.

-"Paradox of the Plankton"

What is the competitive exclusion principle?

two species which compete for same limited resource cannot coexist at constant population values.

What is the number one group that causes algal blooms?

cyanobacteria. they can occur naturally but more frequent due to cultural influences.

Are all phytoplankton in a single taxonomic entity?

NO. they are not all in the kingdom Protista.

-They are in 4+ kingdoms.

What are cyanophyta?

blue-green algae.

prokaryotes.

bacteria that are 2.1 billion years old.

Describe the cell of Cyanophyta.

unicellular, filamentous (trichomes: cells end to end) or colonial, mucliginous sheath

What are heterocysts?

nitrogen-fixing cells. formed by some cyanophyta.

-inactivated by O2

-3 cell walls with glycolipid barrier + produce proteins to bind O2

What are two filamentous forms of cyanophyta?

Oscillatoria

Nostoc

When do algal blooms generally occur?

in warm nutrient rich H2O

-after heavy rainfall or drought

Algal blooms can be?

non-toxic or toxic (HABs)

What are HABs?

harmful algal blooms

What is the annual cost to deal with algal blooms?

roughly $2.2 million