Ways to categorize groups of populations(from Fauth et al. 1996)

guild: organisms that use a shared resource

ensemble

assemblage

taxa: phylogenetically related organisms

hyphenated

Lake Baikal zooplankton

pond-breeding salamanders

local guild

Lake Michigan piscivores

community: all organisms at a location

detritus feeding caracidae (family of fish) in an Andean stream

Community vs Ecosystem

Community = all organisms in area

Ecosystem = all organisms + physical properties of area (rocks, sunlight, weather……)

community structure: types of species, trophic relationships, physical characteristics

community function: rate of energy flow, resilience to perturbation, productivity

Lakes; pelagic, littoral, benthic- more later on types of lakes

Rivers; habitat defined by flow and depth

Estuaries; meeting of river & ocean

Wetlands; defined along gradients- more later

Oceans; most of world’s water- pelagic, littoral, benthic

Miscellaneous habitats; many small out of the way places

Major Aquatic Habitats & Communities

Within-Lake Zonation

First distinction: pelagic zone vs. bottom

Pelagic zone (pelagia) is the open water column

Bottom can be further subdivided

epilittoral

supralittoraleulittoral

spray zone

spray & wavesbetween high & low water

upper littoral; emergent veg

middle littoral; floating veg

lower littoral; submerged veg

littoriprofundal; photosynthetic bacteria & algae

profundal; no vegetation or algae

litto

ral

pelagia

Within-Lake Zones

planktonnekton

benthos

River habitats

pool: deep, slow velocity, fine substrates run: between pool & riffle riffle: shallow, high velocity, gravel cobble substrate

RR

R R

P PP P

flow

P R

P R

P

gravel bars

Oceans

most of the worlds water, most of earth’s surface area

- 4,500m

- 10,000m

-130m

photic zone

littoral zone

neritic waters

continentalshelf

continentalslope

abyssal plain

mid oceanic

ridge

trench

aphotic zone

Oceanic habitats

Miscellaneous aquatic habitats

Natural ponds: can be permanent or ephemeral tree trunks: especially in rainforests pitcher plants: hold simple invertebrate communities

Man madepondsdrainage areas

What interactions among the species adapted to live in a particular place affect the observed community of that place?

Types of interactions between species

consumer - resource interactions

resource consumer

+

-

predation

+

+

competition-

-

consider direction and effect

-

resource consumer

+ mutualism

+

Interactions that involve habitat modification

direction and effect vary depending on interaction

Consider a steam with a beaver dam. Beaver changes stream (lotic habitat) to pond (lentic habitat) & changes some terrestrial habitat to aquatic. The beaver affects every organism living in the area. Doesn’t involve consumption of resources.

Categories of competition

intraspecific competition: between members of same spp density dependent population regulation evolutionary change

Time

po

pu

lati

on

siz

e

K= # that resources can support

resources scarce, competition

interspecific competition: occurs between members of different species (community)

mutually depressing effect on both populations depends on relative efficiency of each population

Interference competition: one individual directly interferes with another’s access to a resource

Chemical: some organisms release chemicals that have negative effect on others- not that common in freshwater

Mechanical: have negative effects due to physical contact

settlement space in marine littoral and streams, maybe lakes too, zebra mussels & native unionids foraging territory defence

Exploitative competition: individuals use the same resource, but at different times,

Strayer & Lane suggest exploitative competition is more important in the Hudson River even though there is often fouling

1991 & 92= low zm, 1993- 95=high zm

zebra mussels found in Hudson in 1991 and became common by 1992

Strayer and Lane. 1998 . Effects of the zebra mussel (Dreissena polymorpha) invasion on the macrobenthos of the freshwater tidal Hudson River. Can. J. Zool. 76(3): 419–425

Zebra mussel infestation of unionids is low in the Hudson

expected #/clam based on observations in other systems

number observed in Hudson

infested proportion observed in Hudson

expected proportion infested clams

but ……. clams are still dying

white = live clamblack = dead clam

Elliptio complanatamost common spp

Anodonta implicata

Leptodea ochracea

low high

Three possible explanations1) decline in live clams part of natural population cycle

long lived 3 spp breed at different times of year, all affected same way

2) even very low fouling can be leathal

many dead shells had no evidence of zebra mussel attachment (byssal threads)

3) zebra mussels out compete unionids for food

phytoplankton 10 -20 % of 1986-1991 levels

Conservation implications

Unionid population at risk identified by level of zebra mussel infestation

May also need to look at populations that experience decline in food level

Ways that aquatic organisms avoid competition

Environmental specialization: ex paradox of the plankton

Habitat partitioning: rotifers & Chydoridae

Resource partitioning: Daphnia vs copepod approach to feeding, live in the same place but use different resources

See pages 166-168 in Dodson

Most Cladocerans filter feed

Ceriodaphnia

Chydorus

Diaphanosoma thorasic legs

Lower particle size determined by how fine ‘spines’ are on filtering comb Upper size set by width of mandibles or carapace gape

http://www.cnas.smsu.edu/zooplankton

carapace gape

Most copepods are raptorial (bite off chunks)

DiacyclopsDiaptomusAcanthocyclops

Can use ‘taste’ chemical properties to discriminate particles

When spp coexist in nature they usually differ somewhat in the way they utilize resources and thus avoid competitive exclusion. Suppose that there are 2 species of chironomid larvae in a pond you are studying. They are the same size, are both active during the same time of day, and live in the same kind of sediment. Explain the observations or experiments that you would undertake to determine how their ecology differed.

How do you explain their coexistence if you can’t find a difference?

In class

Pterygoplichthys scrophus (formerly Glyptoperichthys) Photo by L.M. Page

Megalancistrus aculeatus, photo by K.S. Cummings

scraping mouth parts

Periphyton grazers

http://www.dnr.cornell.edu/sarep/fish/Cyprinidae/stoneroller.html

Stoneroller (Campostoma anomalum)

http://george.cosam.auburn.edu/usr/key_to_loricariidae/lorhome/lorhome.html

some fish

many tadpoles

scraping mouth parts

http://www.whose-tadpole.net/key-to-tadpoles/R-temporaria-LARVAE.htm

Many invertebrates:

snails scrape w/ radulacaddis fly larvae w/ blade-like mandilesmayflies w/ chewing mouth parts

w/ brush-like structures

Predation (animals that eat animals)

Encounter

Attack

Capture

Ingestion

probability predation=PE*PA*PC*PI

P always <1.0, all must happen

Encounter

Ambush: Wait for prey to come to you. Burst speed. Pike, muskie, barracuda, gar, many camouflaged fish, Chaoborus, dragonfly larvae.

Rover: Actively search for food. Constant motion. Bass, perch, copepods, some insect larvae.

http://fcn.state.fl.us/fwc/fishing/Fishes/gar.html

Lepisosteus osseus

Attack: forward (most fish) or sideways (gar) lunge special grasping organs

http://insects.ummz.lsa.umich.edu/michodo/test/index.htm

Odonate larvae mentum extends to grasp prey

Capture:

prey have adaptation to avoid capture piscivores have lots of teeth

two prey fish have different efficiency of capture and handling time

Selectivity

=ri / pi

(ri / pi)

proportion of prey in diet proportion of prey in environment

sum of proportions for m prey itemsm

I=1

X 6 X 10 X 10

Put a bass in a tank w/ above fish. It eats 3 goldfish, 1 bluegill & 3 herring. Calculate selectivity for each.

Almost all fish eat zooplankton early in development

some filter (like a strainer), alewife, gizzard shad & the baleen whales (really really big mammals)

Blue Whale 100 ft, up to 220 tons

http://www.calpoly.edu/~jiturrir/ED480/whales/baleen.html

Planktivory

most fish select individual particles

reaction distance changes with characteristics of the prey and environmental conditions

adult fish tend to select largest, most visible prey, most energy return.

Benthic fish are also size selective; more variability in the strength of the effect of predation on benthic invertebrates.

Planktivorous fish tend to shift the size distribution of plankton to smaller animals

before plantivore introduced

after introduction

Brooks & Dodson 1965

Invertebrate Predators

Most use mechanical or chemical means of detection (a few use vision like fish)

Attack strategies

Encounter:

engulfers: ingest all or most of prey in chunks or whole; most invertebrates, prey usually smaller than predator

pierces: inject digestive enzymes and ingest prey in liquid form; backswimmers, some beetles, leeches; prey can be larger than predator

Invertebrate predators are not much bigger than their prey (compared to adult fish)

probability of encounter is greater for bigger prey

larger prey are harder to subdue and handle

But

Invertebrates may preferentially consume intermediate sized prey

So

Defenses of prey

Coloration: reduce visibility

zooplankton are very clearbenthos have other cryptic colors

Don’t make waves

Bosmina plays dead trade off between feeding and avoiding detection

http://www.cnas.smsu.edu/zooplankton/bosmina.htm

be hard to eat: works best against invertebrate predators or very small fish

gelatinous sheath protuberances

D. ambigua

D. retrocurvaD. lumholtzi

Benthic organisms stay close to the bottom

hide in crevasses make burrows make cases

Timing of activity

time drift when visual feeding fish least efficient time grazing “ “

The cost of defense

constitutive: always turned on

snail shell constant or unpredictable predation no too costly to make

induced: only turn on when threat of predation detected

change in zooplankton body size (mostly) periodic or predictable predation don’t incur the cost till you need it

examples of costs

Energy spent constructing case, shell, body protrusion not devoted to reproduction & may take extra energy to swim

Time spent hiding not spent foraging, avoid death, but lower growth & reproduction

There’s almost always a trade off (no free lunch)

Stream invertebrates must deal with fish (visual) and predatory invertebrates (tactile), good defense for fish may make you vulnerable to inverts.

parasitism(one benefits, at

expense of other)

commensalism (one benefits,

other unaffected)

mutualism (both benefit)

Symbiosis: unlike organisms living together

sea lamprey coral & algae

ectoparasites: found on the outside of hosts

endoparasites: found on the inside of hosts

Epibionts common on Daphnia, including ciliates.

http://www.unibasel.ch/dib/zoologie/ebert/hostpara/daphpato.html

D pulex w/ fungal infection. Fungus grows inside the body cavity and penetrates into all organs and into the extremities.

http://www.unibasel.ch/dib/zoologie/ebert/hostpara/daphpato.html

The Sea Lamprey(Petromyzon marinus)

Native to the Atlantic Ocean Probably entered Great Lakes via the Hudson River and its artificial extension, the Erie Canal (opened to Lake Ontario in 1819)

Gained access to Lake Erie through Welland Canal around Niagara Falls (completed 1829), but not noted in Lake Erieuntil 1921 Thereafter invasion quickened; found in Lake Huron in 1932, Lake Michigan in 1936, and Lake Superior in 1946.

http://www.glfc.org/slft.htm

Lampreys devastated lake trout populations in Great Lakes

Removal of top predator allowed smaller fish such as alewife (also introduced through canals) to boom

Lamprey control (pesticide applied to juvenile form in streams)

Coho & Chinook salmon easier to grow in hatcheries than lake trout. These exotic species were heavily stocked

coral - dinoflagellate associationcoral = invertebrate, phylum Cnidaria

dionoflagelate = unicellular algae (photosynthetic protist) called zooxanthellae

Coral animal gets photosyntheticly produced carbon, algae may also speed production of calcium carbonate in reef producing corals

Algae gets metabolites and and some protection from coral.

soft coral,Xenia, w/ zooxanthellae http://207.254.123.101/solarpow.htm.

Coral reefs widespread and important in marine systems

Many organisms associate with structure formed by reefs (ecosystem engineers) Recent events of coral bleaching (lose of zooxanthellae) related to

rise in ocean temperatureincreased UV-Beutrophication & sedimentation

Organisms that directly or indirectly modulate the availability of resources other than themselves to other species, by causing physical state changes in biotic or abiotic materials. In so doing, they modify, maintain and or create habitats

Jones et al. 1994

Ecosystem Engineers

Examples extensively studied, e.g. beaver, but only recently recognized as important category of interactions

http://sevilleta.unm.edu/data/species/mammal/profile/american-beaver.html

Engineers as keystone specieskeystone species: dominating influence on community, usually regarded as a trophic interactor

autogenic engineers

allogenic engineers

keystone predator

http://life.bio.sunysb.edu/marinebio/kelpforest.html