Seagrass Systems

Question 1

Sea-Otter Social Justice

Answer 1

Demographic component to what is important
First Nations values small intertidal invertebrates
Non-first nations value large commercial fish

The value that otters have, and kelp forest health have a cultural perspective

Question 2

Why are the coastal edge ecosystems (mangroves, salt marshes and seagrass) grouped together?

Answer 2

They are formed by terrestrial plants that have adapted to living in and near the ocean (angiosperms)

“Recent” fully terrestrial ancestor
Convergent evolutionary history
They have similar adaptations for dealing with life in saltwater

Rooted in soft sediment, more connected with soft shore ecosystems

Question 3

Necessary adaptions for life in water (6)

Answer 3

Gas exchange is more difficult
Light attenuation
Osmotic issues with getting rid of salt and retaining water
(Life in water requires more energy)

Stable while rooted in soft sediments
Dealing with anoxic waterlogged sediments
Periodic wholesale tissue and organism loss

Question 4

What is a seagrass

Answer 4

Vascular, flowering plants
Angiosperms, monocots, not true grasses

From large meadows

Exposed to air only during the very low tides

Question 5

Distribution of seagrass

Answer 5

They are widely distributed in temperate and tropical systems
They do not extend as far to the poles as kelp does

Question 6

Productivity of seagrass

Answer 6

They are significant primary producers
550-1100
Less than kelp systems but more steady

They do not rely on upwelling (high nutrient flux of nitrogen)

They have steady nutrient levels so they have relative steady-state productivity

Question 7

Flux

Answer 7

movement with measured parameter and a spatial scale

Question 8

Seascape connectivity

Answer 8

The movements of those measurable parameters across ecosystem boundaries.
Can be biotic or abiotic

Question 9

Allochthonous

Answer 9

Refers to materials that are found remotely from their place of origin
This normally refers to dissolved nutrients

Question 10

Zoster marina

Answer 10

Northern hemisphere seagrass
Favours cooler water
North Atlantic and North Pacific
In the warmer southern range, dies off during warmer seasons

Question 11

Sebastes ssp

Answer 11

Genus of marine fish (rockfish)
>100 species on the west coast (very diverse)
Long-lived and culturally important food source

Question 12

Nearshore seascape connectivity enhances seagrass meadow nursery function - QMM

Answer 12

Question: do adjacent habitats alter the status of the fauna of seagrass systems

Metric: YOY rockfish abundance and condition

Method: Visual abundance surveys and diet/body condition

Question 13

Nearshore seascape connectivity enhances seagrass meadow nursery function - Central Figure `

Answer 13

Figure 4 Reporting Body condition and its relative food source
More abundant and healthier fish at sites with more Calanoid copepod (full of fat)

Question 14

Diversity and species composition

Answer 14

~60 species worldwide
more species diversity in tropics
distribution depends largely on species tolerance and requirements

Question 15

What determines the distribution of seagrass?

Answer 15

Substrate: soft substrates, too much sediment can suffocate plant, too loose sediment can cause biomass loss

Light Availability: very high light requirement (photosynthesis inefficient in seawater), the lower limit set by light availability, turbidity can limit seagrass distribution in shallow environments

Question 16

Basic seagrass morphology

Answer 16

Above ground: strap-like laminate leaves that grow from the sheath as the base of the root

Below Ground: extensive rhizome systems which connect members of the clone

Question 17

Nutrient level effects in seagrass phase shifts

Answer 17

At nitrogen levels above a certain level, seagrass growth saturates.
Algae continue to grow faster and outcompete seagrass
Causes phase shift and algae dominated alternative stable state

Question 18

Reproduction in seagrass

Answer 18

Sexual reproduction is rare and inefficient, allows for the formation of new beds

Vegetative (asexual) growth is more common but still slow (through rhizomes)

Question 19

The seagrass food web

Answer 19

Primary producers: seagrass and epiphytes and other macrophytes

Epiphytes: fouling plants/animals (epifauna) which are animals that attach to the seagrass

Grazers: Mesograzers (small invertebrates such as marine snails) and Macrograzers (sea cows, turtles taking the stalks)

Suspension feeders: taking advantage of the phytoplankton and zooplankton in the water

Detritivores: shredder and deposit feeders

Predators
Mesopredators: medium carnivorous fish feed on mesograzers
Macropredators: shark feed on smaller sharks

Question 20

Mesograzers (small invertebrates

Answer 20

consume algal epiphytes, not the seagrass itself

Unless left unchecked by their predators

Question 21

Macrograzers: Green sea turtle

Answer 21

Young turtles are omnivores
But older turtles become increasingly herbivorous

Long guts and special enzymes to digest seagrass
Selective feeders: choose younger plants more nutritious and easier to digest. Stimulate the growth of new plants
Can be considered gardeners

Question 22

Manatees/Sea cows/Dugongs

Answer 22

Order Sirenia
Only herbivorous marine mammals

Dugong
Feed-in large herds leave feeding trail
massive guts (>30m)
Also cultivation feeders gardeners, prefer Halophila (high nitrogen), dugong grazing stimulates the growth of preferred food

Question 23

Queen Conch

Answer 23

Graze on seagrasses, algae

Predators: eagle ray, loggerhead turtle, southern stingray, hermit crab, spiny lobster, octopus

Question 24

Seagrass in peril

Answer 24

Losing habitat: 15% cover lost 1993-2003

Losing animals: 74 species of concern, fish most affected, seahorses, water quality, overfishing