lake ecology unit 1: module 2/3 part 2 - organisms january 2004

LAKE ECOLOGY

Unit 1: Module 2/3 Part 2 - Organisms January 2004

Developed by: R.Axler and C. Hagley Draft Updated: January 13 , 2004 U1-m2/3Part2-s2

Modules 2/3 overview

Goal – Provide a practical introduction to limnology

Time required – Two weeks of lecture (6 lectures) and 2 laboratories

Extensions – Additional material could be used to expand to 3 weeks. We realize that there are far more slides than can possibly be used in two weeks and some topics are covered in more depth than others. Teachers are expected to view them all and use what best suits their purposes.


Modules 2/3 outline

1. Introduction2. Major groups of organisms; metabolism3. Basins and morphometry4. Spatial and temporal variability – basic

physical and chemical patchiness (habitats)5. Major ions and nutrients 6. Management – eutrophication and water

quality


2. Lake organisms

Aquatic organisms may be classified as: Those that go where they choose Those that go where the water takes them Those that live on the lake bottom


Those that go where they choose

Organism photos

MN DNR

MN DNR


Dead stuff = detritusLiving things = plankton

Animals = zooplankton

Plants = phytoplankton

Bacteria = bacterioplankton

Internal = autocthonous(produced in the lake)External = allocthonous

(washed in from watershed)

Those that go where the water takes them

http://www.saskschools.ca


Those that live on the lake bottom

BENTHOS = animals crustaceans, worms molluscs, insects


Those that live on the lake bottom - cont.

PLANTS higher plants (macrophytes) and attached algae

(periphyton)

NRRI image


Those that live on the lake bottom - cont.

BACTERIA & FUNGI sewage sludge, aufwuchs (slime of algae, fungi,

bacteria


Plants – phytoplankton – major habitats

Algae Phytoplankton (float freely in the water) Periphyton (attached to aquatic vegetation,

rocks, wood and other substrates) Benthic algae (grow on the lake

bottom/sediments); also sometimes called periphyton


Plants – phytoplankton – major groups 1

Greens grass-like pigments; unicells, filaments, colonies; starch

storage Diatoms

silica walls, preserve well in lake sediments (paleolimnology); edible; high light and cool water; lipid storage

•http://www.microscopy-uk.org.ukhttp://www.susqu.edu/biology/algae/



Blue-greens – cyanobacteria “inedible” (less-edible); bloom/scum forming; N2-

fixers; P-storage; toxic forms

NRRI image

Aphanizomenon Aphanizomenon

NRRI Image

“Annie” “Fannie”

http://microbes.limnology.wisc.edu/outreach/importance.php

“Mike”

Microcystis Microcystis Chroococcus Chroococcus

Anabaena Anabaena

Aphanizomenon Aphanizomenon



Dinoflagellates, cryptophytes, chrysophytes Edible Flagella - some can “migrate” to optimal light, temp Taxa-specific accessory pigments Bloom forming toxic tides (red and brown; harmful

algal blooms; Pfisteria hysteria)

NRRI Image


Algae – major growth forms

colonialcolonial

unicellularunicellular

filamentousfilamentous

scumscum

branched branched

unicellunicell


Too much can yield a nasty bloom

•http://microbes.limnology.wisc.edu/outreach/importance.php


Phytoplankton – succession

There are always many species abundant “somewhere” in the water column or littoral zone


Phytoplankton succession cont.

Algal biomass is low in early spring due to low light and cool temperatures

As sunlight increases diatom biomass will often increase due to high nutrients from turnover and spring runoff

Greens do well as water warms, high light from long days

Blue-greens do well in warmer water can store P some fix N2 most are “less edible” buoyancy helps with light

Late summer-fall brings mixing and light-limitation, nutrient inputs, decreased grazing


Chlorophyll-a: a good estimator of algae

The primary photosynthetic pigment in all plants

“Easily” measured with a spectrophotometer or fluorometer

Accessory pigments now used for estimating the major groups of algae


But increased algae isn’t always bad…

Although increased algal growth results in decreased water clarity…..

More food at base of food web leads to increased fish yield

But not always the fish you want

Schematic from NALMS. 1990. The lake and reservoir restoration guidance manual. 2nd edition. North American Lake Management Society and USEPA Office of Water, Washington, D.C. EPA-440/4-90-006 August 1990.


Attached algae – periphyton

Periphyton is often categorized by the substrate on which it grows: Epilithic (rocks) Epiphytic (on plants) Epipelic (soft sediments) Epipsammic (sand)


Attached algae – periphyton cont.

Ecological differences from phytoplankton Fixed depth re light, wave action and

temperature zones Closer to sediment nutrient sources Exposed to higher levels of nutrients from

watershed May act as biofilter on the sediments in

unproductive lakes Interactions with macrophytes


Plants – macrophytes – growth forms

• Floating-leaf: near-shore unless sheltered, rooted or floating roots

• Submergent: rooted and growing underwater from shoreline to several meters deep; leaves may be floating • Emergent: above shoreline to about knee-deep; roots may be underwater but grow and flower aerially; tolerate fluctuating water levels; dense stands can dampen wave action

http://aquat1.ifas.ufl.edu/\


Macrophytes- floating leaved

Floating-leaved macrophytes

NRRI image

Watermeal Watermeal (Wolffia)(Wolffia)Water liliesWater lilies duckweedduckweed

duckweedduckweed


Macrophytes- submergent

Submergent macrophytes

MilfoilMilfoil

water celerywater celery

curly-leaved pondweed

PotamogetonPotamogeton

(pondweed) (pondweed)

CharaChara (an alga)(an alga)

Isoetes (quillwort)Isoetes (quillwort)

Pondweed?Pondweed?


Higher aquatic plants (macrophytes)- emergent

Emergent macrophytes

Pitlake emergent vegetationMead Xmas tree bloom

reeds cattails bulrushes Spirodella

carnivorous


Plants – macrophytes – key features

Macrophytes are vascular (rooted) plants Often called “weeds” Can be excessive from nutrient enrichment –

especially by exotic, invasive species at disturbed sites

Difficult to re-establish once removed


Plants – macrophytes – key features

Ecological importance: structural habitat & spawning site food for invertebrates, fish, and

wildlife stabilize shoreline and bottom

sediments important in nutrient cycling

(sediment nitrogen and phosphorus)

may light-limit phytoplankton in productive systems

Prevent the spread of invasive species


Bacterioplankton – Microbial loop: major food chain pathway through

microzooplankton Nutrient (C, N, P) recyclers (water & sediments)

Pathogens (disease-causing) Fecal coliform bacteria = indicator of human feces E.coli – more specific But – only a warm-blooded animal indicator

Microbes – importance

9b.jpg


Ciliated protozoans Rotifers Crustaceans

Cladocerans Copepods

Migrating benthos (Mysids, Neomysids, Diaporeia, etc)

Insects

Zooplankton – Major groups

http://www.biosci.ohio-state.edu/~eeob/eeob405/labs/protista.html

VorticellaVorticella

KeratellaKeratellahttp://www.stetson.edu/~kwork/favorite.htm

amphipodamphipod cyclopoidcyclopoid


Zooplankton – key features - cladocerans

Cladocerans (e.g. water fleas) Size: 100 –300 microns Migration – can be ten’s of meters daily Slow moving (relative to copepods and hungry fish) Selective feeders (edible vs inedible algae) Parthenogenic – “r-selection”, rapid reproduction Very effective at clearing the water column

HolopediumHolopediumChydorusChydorusBosminaBosmina

DaphniaDaphnia


Zooplankton – key features - copepods

Calanoids, Cyclopoids and Harpacticoids : Size: wide range overlaping cladocerans Cyclopoids often predatory Faster moving – less affected by fish predation Selective feeders (edible vs inedible algae) Many life stages and slower growing – “k-selection” Distributed more evenly over day, seasons, depth

calanoidcalanoidcyclopoidcyclopoid harpacticoidharpacticoid


Zooplankton - Rotifers

Size: small <150 microns Some able to migrate 10’s of meters daily Slow moving but small size offers some

protection from adult planktivorous fish Less selective feeders (algae, bacteria,

protozoans, detritus); not well understood Parthenogenic – “r-selection”, rapid reproduction

Kellicottia

PolyarthraKeratella


Protozoa - animal-like, single-celled organisms: amoebas, ciliates

• The terms algae and phytoplankton are used for the more plant-like forms that are photosynthetic

• euglenoids, cryptomonads, dinoflagellates• All these organisms together = Kingdom Protista• Not well studied – very important to bacterioplankton and

nutrient cycling in unproductive systems

Zooplankton - ciliated protozoans


Zooplankton – ciliated protozoans

© www.micrographia.com


• Predatory & filter feeding insects• Raptorial predators• Amphipods & migrating benthos• Includes:

• Mysids (oppossum shrimp), • Diaporeia and other amphipods (sideswimmers/scuds;

Hyallela for toxicity testing)• Chaoborus (phantom midge extremely predacious)

Leptodora

Mysid Chaoborus Scuds

Diporeia

Big zooplankton - diversity


Big zooplankton - ecology

• Play an important role in fish-less lakes by structuring the smaller zooplankton communities through predation or competition

• Some migrate hundreds of meters (mysids) from benthos

• Extremely important as fish food in larger lakes


Benthos – wormsBenthos – worms


Fish

The best known group of aquatic consumers Different species exploit different habitats (niches)

Bass and pike are found in lakes that have beds of aquatic macrophytes suitable for spawning

Walleyes, on the other hand, spawn on a gravel bottom. Lake trout live only in very clear lakes with cold, well-

oxygenated deep water In contrast, carp are adapted to warm turbid, low oxygen

lakes with mucky, high organic matter bottoms


Fish – feeding guilds

Most fish are somewhat opportunistic in their feeding habits but in general, the majority of the food they eat enables fishery biologists to place them into feeding guilds. Planktivores – consume zooplankton Benthivores – consume benthos Piscivores – consume fish Detritivores – consume organisms that live on detritus or

mud (biofilm) Omnivores – consume a variety of foods opportunistically

Walleye - drawn by Bob Savannah for the US FWSTop minnow – WI DNR image


Fish – thermal guilds

Temperature is important to fish at all levels of biological organization.

Temperature effects fish both: Individually

Affects development and growth rates And at the population level

SurvivorshipMortalityPopulation yield


Fish – thermal guilds - coldwater

Coldwater prefer temperatures

below 15 C Upper lethal

temperature is ~ 24 C Includes trout,

salmon, sculpins

brook troutbrook trout

chinook salmonchinook salmon

sculpinsculpin

http://www.gen.umn.edu/research/fish


Coolwater Prefer temps between

18 and 23 C Upper lethal temp is

~31-32 C Includes perch,

walleye, suckers

Fish – thermal guilds - coolwater


http://www.cnr.vt.edu/efish/families/clupeidae.html

suckersucker

walleyewalleye

perchperch


Fish – thermal guilds - warmwater

Warmwater Prefer temps above 25 C Upper lethal temperature exceeds 33 C Includes basses and sunfish


bluegillbluegill large mouth basslarge mouth bass


Food chains and webs - simple

Organisms can be organized into food chains & food webs of varying complexity


Food webs - sublime

Probably more realistic ecologically, but perhaps useless to managers

But be aware of not-so-obvious complexities


Microbial loop

Food and energy transfers in lakes


Metabolism

Organisms need: Energy source(s) Carbon for structure and for synthesizing

enzymes, nucleic acids, sugars, lipids, etc Mineral nutrients – CHNOPS, trace metals


Metabolism

Essentially two categories of metabolism: Autotrophic (self-feeding) – produce organic

matter by yourself Heterotrophic (other-feeding) – eat living or

dead organic matter Plants photosynthesize; most of their mineral

nutrition is from the water (inorganic form) Animals eat mostly organic stuff


Energy metabolism - Autotrophic

Photosynthetic – using light energy to fix CO2

Plants (aerobic); certain anaerobic bacteria Chemosynthetic – using chemical energy to fix CO2

Certain aerobic bacteria (oxidize NH4, H2S, Fe+2, CH4, and more)

DICCO2: dissolved inorganic carbon

POCParticulate organic carbon


Energy metabolism - Heterotrophic

Aerobic respiration - uses O2 Algae, plants, animals, many bacteria

Anaerobic fermentation - uses nitrate, sulfate, … Various groups of bacteria that may only survive in the

absence of oxygen, or may switch their metabolism based on the presence or absence of oxygen

POC + DOCParticulate + dissolved organic carbon

DICDissolved inorganic carbon


Trophic (feeding metabolism) terminology

Oligotrophic – low nutrients and “productivity;” usually high clarity

Mesotrophic – moderate nutrients, “productivity” and clarity

Eutrophic – high nutrients and “productivity;” low clarity

lake ecology unit 1: module 2/3 part 2 - organisms january 2004

Documents

hagley draft

lake bottombenthos

lake bottomsediments

lake bottomdeveloped

lake ecologyunit

water qualitydeveloped

substratesbenthic algae

weeks of lecture