Lecture 17- Marine/Pelagic Food Webs

Question 1

pelagic

Answer 1

the water column environment

Question 2

benthic

Answer 2

• the sea floor environment

- includes coral reefs and rocky intertidal

Question 3

plankton

Answer 3

unable to swim horizontally against ocean currents but may move vertically in the water column

Question 4

nekton

Answer 4

• able to swim against ocean currents

- fish, squids, sea turtles, dolphins, whales

Question 5

holoplankton

Answer 5

• planktonic organisms that live their entire life in fluid suspension
• copepods, shrimp, arrow worms, some jellyfish

Question 6

meroplankton

Answer 6

• planktonic organisms that spend only part of their life in fluid suspension
• crabs, barnacles, oysters, fish larvae

Question 7

autotrophs

Answer 7

• group of organisms whose energy/carbon come from nonorganic sources
• ex. phytoplankton because they use sunlight and CO2 for their energy and carbon needs

Question 8

heterotrophs

Answer 8

• group of organisms whose energy/carbon for growth comes from previously formed organic carbon material
• Ex. Herbivorous zooplankton are heterotrophs because they consume phytoplankton for their energy/carbon needs
• Carnivores are also heterotrophs

Question 9

trophic level

Answer 9

nutritional feeding level within a food chain or web

Question 10

first trophic level

Answer 10

primary producers (phytoplankton)

Question 11

top trophic level

Answer 11

fourth consumers

Question 12

primary consumer

Answer 12

herbivore

Question 13

secondary consumer

Answer 13

first carnivore

Question 14

first question to assign organism to particular trophic level

Answer 14

autotrophic or heterotrophic?

Question 15

if organism is an autotroph

Answer 15

it contains chlorophyll

Question 16

second question to assign organism to particular trophic level

Answer 16

if the organism is heterotrophic, is it primary, secondary, etc. consumer?

Question 17

optimal prey size

Answer 17

• set by consumer’s mouth size

- usually 1/10 the size

Question 18

marine food webs are said to be

Answer 18

strongly size structured

Question 19

overall trophic transfer efficiency are affected by

Answer 19

• exploitation efficiency
• gross production efficiency
• trophic transfer efficiency

Question 20

exploitation efficiency

Answer 20

efficiency with which a consumer population is able to find, capture, and ingest all of the potential prey present in the environment

Question 21

gross production efficiency

Answer 21

the physiological/biochemical efficiency of converting ingested prey into consumer biomass

Question 22

trophic transfer efficiency

Answer 22

exploitation efficiency X gross production efficiency

Question 23

strategies for finding prey

Answer 23

• locomotion

- perception

Question 24

locomotion

Answer 24

• cruising: rely on your own locomotion to encounter prey

- ambush: rely on the locomotion of your prey to come to you

Question 25

perception

Answer 25

• visual perception
• mechanosensory
• chemisensory

Question 26

strategies for capturing prey

Answer 26

• raptorial
• direct interception
• filtering
• entanglement

Question 27

raptorial

Answer 27

grasp prey with appendages

Question 28

filtering

Answer 28

sieve large volumes of water

Question 29

strategies to avoid/escape predation

Answer 29

• avoid encounter or detection
• frustrate the capture process
• bioluminescence

Question 30

frustrate the capture process

Answer 30

• very small or large size
• spines: mechanical defense
• escape response
• schooling

Question 31

diel vertical migration

Answer 31

• much of the zooplankton community migrates up to the surface layer of the ocean at night to feed in the dark
• during the day, they migrate down to the safety of the darkness

Question 32

spring blooms in the temperate North Atlantic region

Answer 32

• during the long winter periods, large grazers sink into the ocean and enter diapause (hibernation)
• in spring, phytoplankton grow to high density
• low exploitation efficiency because grazers aren’t there to eat the phytoplankton

Question 33

tropical environment

Answer 33

• small grazers remain active throughout they year and consume phytoplankton as fast as it is made
• exploitation energy is very high: almost all phytoplankton is consumed by grazers

Question 34

gross growth (production) efficiency

Answer 34

amount of consumer biomass produced divided by amount of prey ingestion

Question 35

gross growth (production) efficiency range

Answer 35

between 20 and 60%

Question 36

overall trophic transfer efficiency

Answer 36

about 10-20% but we will use 10%

Question 37

coastal upwelling regions

Answer 37

number of trophic levels between phytoplankton and harvestable fish is smaller in high nutrient regions

Question 38

open oceans

Answer 38

7 trophic levels

Question 39

continental shelf

Answer 39

4 trophic levels

Question 40

upwelling regions

Answer 40

3 trophic levels

Question 41

highest production of harvestable fish is in the

Answer 41

coastal ocean region

Question 42

upper limit on the total biomass of harvestable fish in a given ocean province is determined by

Answer 42

• intensity of primary production- number of trophic levels between primary producers and harvestable fish and the trophic transfer efficiencies