1. Lect07 Marine Ecosystems

2. Lect07 Marine Ecosystems
Estuaries
Marine Shores
Shallow Marine Waters
Oceans

3. An estuary is a transition area between river and sea
Estuaries
An estuary is a transition area between river and sea
Barrier to flooding
Filter for terrestrial pollutants
Usually found where rivers meet the sea
Salinity varies with the rise and fall of the tides
Estuaries are nutrient rich and highly productive
Primary production: salt marsh grasses, algae
An abundant supply of food attracts marine invertebrates and fish
Worms, oysters, crabs – etc – support water fowl, fish
Important as nurseries of many fish spp.

4. Salt Marshes and Mangrove Forests

5. Characteristic Regions of Estuarine Habitat Important factors:
Sediment size
Exposure during tidal flux
Aquatic Bed
Eelgrass – supports epiphytes, prevents erosion, traps sediment
Tidal Flats
Store heat, varied salinity, oxygen issues
Low and Middle Marsh/salt march – pickle weed, cord grass, mangrove

10. Issues in Estuaries
Excessive nutrients from adjacent terrestrial areas  eutrophication  anoxia
Silt accumulation
Invasive species
Impacts of development

11. Elkhorn Slough One of a limited number of estuaries along CA coast
Relatively well preserved, still – many issues

12. Changes in Elkhorn Slough Diversion of Salinas River
Increased tidal flow
Sediment loss
Construction of railway embankment
Loss in salt marsh habitat (50% since 1931)
Soil compaction and subsidence
Channel widening

16. Coral reefs: formed from the calcium carbonate skeletons of corals (phylum Cnidaria)
require a solid substrate for attachment
mutualistic relationship with algae provides corals with organic molecules
Highly diverse community

17. A coral reef in the Red Sea
Fig i
Figure Aquatic biomes
A coral reef in the Red Sea

18. Intertidal Zones
An intertidal zone is periodically submerged and exposed by the tides
variations in temperature and salinity
the mechanical forces of wave action
structural adaptations that enable attachment hard substrate

19. Rocky intertidal zone on the Oregon coast
Fig g
Figure Aquatic biomes
Rocky intertidal zone on the Oregon coast

20. Oceans - Geography Cover 70% of earth’s surface Average Depth
Pacific - 4,000 m
Atlantic - 3,900 m
Indian - 3,900 m
Undersea Trenches
Marianas - 10,000 m deep
Would engulf Mt. Everest with 2 km to spare.

21. Marine Systems – Regions
Littoral: intertidal
Benthic: refers to sea bottom
Neritic: ocean over continental shelf - ~ m
Oceanic: Continental slope to open ocean

22. Oceans - Structure Oceanic Zone: Beyond continental shelf.
Epipelagic m
Mesopelagic ,000 m
Bathypelagic 1, ,000 m
Abyssal 4, ,000 m
Hadal 6,000 + m
Benthic: Habitat on bottom of ocean.
Pelagic: Habitat off the bottom of the ocean.

23. Neritic Zone – Over continental shelf
Oceanic Zone – From continental shelf to open ocean

24. Ocean Currents: movement of large masses of water
Driven by steady winds, interrupted by land masses
Influenced by temperature + salinity differences
Gyres: large circular movements that circulate around an oceanic basin
counterclockwise in southern hemisphere
clockwise in northern hemisphere

25. Impact of Gyres
move warm waters northward or southward  warm the climate of the land
example is the Gulf Stream in the North Atlantic, which so warms western Europe that palm trees grow in southern Ireland
move cool water south
Example: California Current  cools west coastal climate

26. What affects life in the ocean?
Light – only penetrates to upper few meters
Nutrients – absorbed quickly by living things – become limiting factor
Temperature
Salinity
expressed as parts per thousand
0/00
Varies with depth, region (evaporation, fw inputs)

27. Carbon and oceanic waters
CO2 dissolves in surface waters  bicarbonate ions
Slow mixing with deeper waters
Reaches equilibrium with atmospheric CO2
Bicarbonate in water
Incorporated into organic compounds and animal shells as CaCO3 & falls to bottom
Incorporated into rock (limestone sediments)
Adds to carbon reservoir
Acidification of surface waters

28. From wikimedia

29. Temperature Stratification: Sunlight waters warmer – less dense
Cooler waters are more dense
Thermocline: area of temperature transition – between temperature strata

30. Nutrients in oceanic ecosystems
Less in euphotic zone due to scavenging by phytoplankton
Greater below euphotic
Nutrients tend to be limiting
Iron especially a factor
Enrichment may lead to phytoplankton blooms
Upwellings: bring nutrients in deeper waters to surface – stimulate entire food chain

31. Aquatic Food Chains and Pyramids
An inverted pyramid – larger biomass in consumers than in producers
Populations able to increase rapidly
Nutrient turnover much more rapid than in other ecosystems
Producers short-lived - die or are consumed
Energy in producer level converted to biomass of consumers

32. Deep-Sea Waters – no primary producers, rely on energy from photosynthetic activity of euphotic
Little light penetrates beyond the top 300 meters
Relatively few, bizarre, organisms live there
Some fish have bioluminescent body parts
Sea anemones use glass-sponge stalks to catch falling particles

33. Hydrothermal vent systems (deep-sea vents) support a broad array of living organisms
Autotrophic prokaryotes obtain energy by chemosynthesis
Extract energy from hydrogen sulfide to manufacture food
Live symbiotically within the tissues of heterotrophic animals

34. Summary – Marine Ecosystems
Various factors impact life in the ocean – most limiting are light and nutrients
Marine ecosystems may be considered an inverted pyramid, energy cycles quickly through system resulting in greater biomass of consumers than producers/prey
Factors that introduce nutrients to marine systems result in rapid increase in growth/development of food web