exam 3 lecture

Positive feedback

(amplifiers): increase leads to increase, decrease to decrease

Negative feedback

(stabilizers): increase leads to decrease, decrease to increase

Properties of all cellular life (unity and diversity)

-Compartmentalization and metabolism - Growth - Evolution

How do we know timescales

-Direct observations -Stratigraphy and Fossil records -Radiometric dating -Time

Earth = closed system to all elements* heavier than He

-Finite resources - Changes propagate through system - Powerful constraint on our understanding -(also, no throwing things "away")

What role do mangroves play in coastal communities?

-capture carbon dioxide through primary production -protect our coasts from the destructive forces of hurricanes -create safe nurseries for young fish

Three key principles for chemical processes:

1) Mass is conserved: # atoms of each element does not change 2) Energy is conserved: total energy is constant, but can change form 3) Process takes time: rates of reactions

Coral reefs cover less than [A] % of the seafloor, yet they are home to [B] of all marine species.

1, 1/4

Simple tools for understanding biogeochemical cycles

1. Define your system (Earth is open system to energy, nearly closed system to matter) 2. Identify components of system - Reservoirs -"Fluxes" (Sources and sinks) - Budget = list of sources and sinks

Charles Darwin's Main points

1. In any group of organisms, more offspring are produced than can survive to reproductive age. 2. Random variations occur; some are inherited by offspring 3. Some inherited variations make offspring better suited to environment 4. Reproduction of offspring with new trait allows traits to accumulate in population. 5. The natural (physical + biological) environment selects favorable traits. examples: camouflage reduces predation, beak shape and/or enhanced vision make new food sources accessible. If environment changes, selection changes

The Biological Pump (carbon and nutrients)

1. Primary production: 2. Export: 3. Regeneration:

The sea's fringing lands make up less than [A] of the world's oceans', yet, astonishingly, [B] % of all marine creatures live in these coastal waters. This super abundance is due to the fact that the seafloor is within reach of sunlight.

1/10, 90%

When did scientists first discover communities surrounding unusual "underwater lakes" at the bottom of the ocean?

1990

The geological processes that produce methane also produce sulfides, therefore it was not surprising that scientist also found tube worms near the the cold seep community. However, unlike the fast-growing Riftia tube worms found at hot hydrothermal vents, these tube worms are slow growing and long lived. How old were these tube worms?

200 YRS

Through primary production, "seagrasses absorb ________ as much CO2 as the same area of rainforest, and that reduces the damage caused by the recent warming of our seas."

35x

The Pompeii worm is record-breaking polychaete worm that survives in seawater reaching a temperature of [A]°C; no other animal was known to tolerate such high temperatures

80

sources

= amounts added (e.g., 2.8 × 108 m3 H2O / yr from rivers + rain)... ...

sinks

= amounts removed (e.g., 2.8 × 108 m3 H2O / yr evaporated)

Cell

= compartment that takes up nutrients from environment, transforms them, and releases waste

Natural Selection

A mechanism of evolution that results in the continuation of only those forms of life best adapted to survive and reproduce in their environment

Regeneration:

CO2 & nutrients regenerated by respiration of OM in deeper ocean

Compartmentalization and metabolism

Cell = compartment that takes up nutrients from environment, transforms them, and releases waste

Evolution

Cells contain genes (DNA instructions) and evolve to display new biological properties. Relationships shown on "phylogenetic trees"

Growth

Chemicals from environment are turned into new cells under genetic direction of preexisting cells.

salt marshes

Coastal wetlands that are regularly flooded at high tide and characterized by salt tolerant plants growing in nutrient-rich, hypoxic sediments. Much of their high primary productivity comes from sea grasses, mangroves, and other vascular plants that can prosper in a marine (or partly marine) environment.

coral reefs

Linear masses of calcium carbonate (aragonite and calcite) assembled from coral organisms, algae, molluscs, worms, and so on. Coral may contribute to less than half of the reef material. The coral animals themselves construct the reefs by secreting hard skeletons of a crystalline form of calcium carbonate.

What is the main energy source for chemosynthesis in the marine community surrounding this cold-seep pool of brine?

Methane bubbling out of the seabeds

Given what you have already learned about plate tectonics, why do you think that the tube worms growing near hot hydrothermal vent systems on mid-ocean ridges and near hot spots evolved to grow so much faster than the tube worms growing near the cold seep in the Gulf of Mexico? Explain your answer.

Mid-ocean ridges are caused by seafloor spreading when the new oceanic crust is being formed. When hydrothermal vent systems develop on mid-ocean ridges, the worms living there are very-short lived because of the new crust that is always forming. Because of this process, the tubeworms adapted to growing faster. On the other hand, cold seeps are more stable and the organisms living there are some of the longest-lived.

Direct observations

Organisms with short generation times can be observed (bacteria, fruit flies, etc.)

Radiometric dating

Radioactive elements in fossils and rocks record their ages

Stratigraphy and Fossil records

Rocks accumulate in horizonal layers, with more recently deposited layers on top, older layers beneath; - Fossils in deeper layers are relatively older

Briefly, explain why sea otters are such an important component of Kelp forest communities

Sea otters need to eat a lot to stay warm and consume about a quarter of their body weight a day. They are an important component of Kelp forest communities because they help keep the number of sea urchins normal by eating them. Id sea urchins are left to stay around, they will graze on the kelp and eat through their stems. If there is no balance from the sea otters eating the sea urchins, they will take over the seabed.

2. Export:

Some densely packaged organic particles sink .

At the surface of the ocean, water becomes steam at 100°C, but down here under the immense pressures at the bottom of the sea, water can remain a liquid at temperatures of almost 400°C.

T

Net primary production (NPP) should increase the concentration of organic matter and decrease the concentration of CO2 in the euphotic zone.

T

The "water" in the underwater lake was actually a thick brine (which is very salty water) that is denser than the surrounding seawater and which settled into a depression on the seafloor

T

The concentration of phosphate (PO43-) in the deep ocean (~2000 m below the sea surface) is highest in the North Pacific Ocean.

T

The hot hydrothermal vent communities typically last for only a few decades. They are populated by some of the fastest growing species, including the large red tube worms (Riftia) that reach approximately 2 meters long (approximately 6.5 feet long).

T

The lowest concentrations of dissolved O2 in the deep ocean (about 2000 below the surface) are found in the North Pacific Ocean.

T

Until the symbiotic tube worms (Riftia), crabs, clams and other creatures surrounding hydrothermal vents were discovered (in 1977), we believed that all life on earth was dependent on the sun.

T

rocky intertidal zone

The band between highest high-ticde and lowest low-tide on a rocky shore. These are one of Earth's most densely populated areas. Hundreds of species and individuals crowd this junction of land and sea.

1. Primary production:

consumes CO2 & nutrients, makes organic matter (OM) in euphotic zone

Sinking POC flux decreases with depth due to

decomposition • dissolution • net disaggregation • NOT MAGIC!

What is the main source of energy used by chemosynthetic primary producers in the hot hydrothermal community surrounding the "black smoker"

hydrogen sulfide dissolved in the hot hydrothermal fluid

A ________ is "a species that play a significant ecological role in the structure and function of an ecosystem. If removed, the loss of the species can have a dramatic effect on community structure."

keystone species

Biogeochemistry

movement & transformation of materials through living & non-living forms & locations

Biogeochemical cycle

movement & transformation of materials through living & non-living forms & locations -As name implies, the materials are processed by living & non-living parts of Earth

The open water environment (extending from the seasurface to the seafloor) is called the [A] zone and is divided into two subsections: the [B] zone is the water environment that is nearshore and above the continental shelf; and the deep water [C] zone, is the water environment beyond the continental shelf. The bottom environment is labeled [D] and begins with the intertidal littoral zone, which is the band of coast that is alterately covered and uncovered by the flood and ebb of the tides.

pelagic, neritic, oceanic, benthic

Primary productivity

rate of organic matter synthesis from inorganic materials by organisms per unit area or unit volume

"Fluxes":

rates of addition or removal from reservoir (dimensions = amount /time) Could be "routes" or "reactions"

What are the defining primary producers in this community?

seagrass

What roles do giant kelp play in kelp forests?

shelter food source nurseries

List at least two animals that live in this cold seep community?

shrimp, spot lobsters, and red polychaete wormS

Steady State:

when sources = sinks; no apparent change in reservoir over time

Earth = open system with respect to energy

• Intercepts sunlight; absorbs/reflects & re-radiates

vent and seep communities

These systems are characterized fluids that emerge from the seafloor, often containing a mixture of solutes that is distinguishable from overlying seawater. Some of these systems in the deep ocean are far from sunlight, but still support thriving communities because some chemosynthetic primary producers have evolved to extract the energy contained in these solutes (for example, from hydrogen sulfide), rather than sunlight, to synthesize organic molecules. An example of a remarkable, mutually beneficial relationship between two organisms, are the Riftia tube worms. These worms are heterotrophs, and their bodies contain masses of chemosynthetic bacteria that provide the nutrition that they need.

kelp forests

These underwater forests are dominated by large marine multicellular algae (that we informally call seaweeds) called kelp, which can grow at a rate of 50 cm per day (!) and reach a legth of 40 meters! When light and nutrient conditions are optimal, large algae can make carbohydrate molecules so rapidly that they leak from their tissues like tea from a tea bag. They provide shelter and nutrition for organisms, serve as nurseries for others, and host a diverse community of pelagic and benthic organisms (including sea urchins). Sea otters may eventually move in to eat the urchins and act as keystone species that dramatically shift the structure and composition of the kelp forest community.

How do large numbers of powerful top predators, like sharks, assist in maintaining the health of reefs

They help to keep a balance in the community, but hunting the predators that feed on smaller fish; the smaller grazers then clean the corals of seaweeds and parasites.

Budget:

a balance sheet of sources and sinks. Example: Budget of water in lake

Reservoirs:

amounts of material in a form of interest

Residence time (τ):

average time spent in reservoir, or "time to empty reservoir with constant sinks but no sources"

Tree of Life

Evolutionary Relationships between all species -Closer together = more closely related. - Branches closer to trunk = less similar, and evolutionary divergence in more distant past

The concentrations of dissolved CO2 and nutrients such as nitrate (NO3-) and phosphate (PO43-) are generally lower in the surface ocean than they are in the deep ocean. This is because ______ moves these substances from the surface ocean to the deeper ocean via three processes: 1. Primary production consumes the CO2 and nutrients in the euphotic zone to make organic matter. 2. Some of that organic matter sinks to deeper water. 3. Respiration of the sinking organic matter regenerates the CO2 and nutrients in the deeper waters.

biological pump