Marine Ecology Exam 3

T or F: Most of Earth’s surface is under the ocean?

True

What are some adaptations to the challenges of living in the deep ocean?

1) Handle long periods of time without food

2) Not have a swim bladder because of high pressure

3) Bioluminescence to attract other members of same species

Why are deep oceans suprisingly species rich despite low biomass? 

Niche diversification, low comp for resources, slow (allows things to coexist) 

Long term stability of conditions 

Why is there a latitudinal trend? 

Higher productivity → get more stuff coming down = higher species deep sea richness along coast + equator 

Hydrothermal vents - where do they occur, what is the smoke?

“Black smokers”

water emerges at 400 degrees

occur at spreading of tectonic plates, heating by magma, seeps where water can enter 

smoke is mostly sulfides emitted by the vent 

WIs water more or less turbid at vents and why?

More turbid (cloudy) because of higher productivity

What factors drive hydrothermal vent systems? In other words what are the challenges of the deep sea that vents can counteract? 

žHigh pressure

žLow temperature

žLack of sunlight

žLack of photosynthesis

žScarcity of food resources

žEnormous volume of water further reduces encounter probability

How do vents counteract those challenges?

žChemosynthetic bacteria (primary producers)

CO₂ + O₂ + 4H₂S → CH₂O + 4S + 3H₂O

žHot, mineral-rich water

žOne Location (meeting place hypothesis) 

How long are vents active for?

Are species the same or different at vents? 

žVents active for years or decades

žAnimals species remarkably similar at widely separated vents (fill same niche)

—Larvae drift from site to site

—“Dead whale hypothesis”

Succession in hydrothermal vents

žNew vent forms at diverging plates

žChemosynthetic bacteria (oxidize inorganics e.g., H₂S)

žGrazers: Amphipods, copepods, limpets

žFilter feeders: limpets, clams, mussels

žScavengers: vent crabs, worms, fish

žPredators: vent crabs, octopi

žSymbiotic with primary producers (bacteria): vestimentiferan worms, giant clams (tube worms/giant clams have bacteria in them which get energy from sulfide in vents, these org only house the bacteria, not heterotrophic)

Why deep sea org pigment free except red? 

They can’t be seen, no light available to bounce off (don’t need to produce pigments), red is first color on spectrum to be filtered out by water, can’t see them at certain depth 

Global methane seeps/cold seep

Frequency higher along areas of plates for vents

subduction zones -/ = methane seeps 

What factors drive methane vent/cold seep?

Same deep sea challenges

How do methane seeps counteract these challenges?

žChemosynthetic bacteria (primary producers)

žCold, mineral-rich water

žOne Location

How are methane seeps different than vents?

žChemosynthetic bacteria typically use methane

žMore stable than hydrothermal vents

žContain longer lived organisms

žIncluding: Lamellibranchia worms which may be the longest lived non-colonial inverts

What is an estuary?

žPartially enclosed body of water where two different bodies of water meet and mix

—E.g. Freshwater from rivers and the saltwater from the ocean OR small rivers meet a very large lake that are chemically distinct from each other (Freshwater estuaries common to the Great Lakes)

—Salt and fresh mix = brackish water

žClose interaction between the land and sea

—Estuaries and estuarine biology closely tied to watersheds

○The surrounding land that provides water input to the estuary

Estuaries are the most productive ecosystems on earth and have the most impact from and to people? T or F 

T

How are types of estuaries differentiated? What are the diff types? 

žDifferences are based on surrounding landforms
and geomorphology

žCoastal plain/ Drowned river valleys

—rising sea levels filling an existing river valley

žTectonically produced estuaries

—tectonic plates shifting together and drifting apart

žBar-built / lagoon

—body of water protected from the ocean by a sand bar
or a barrier island

žFjord-type estuary

—created by glaciers carving out a deep, steep valley

What is an estuary in CT? Where are the river inputs from? What kind of estuary is it?

—River inputs from NY, CT, MA and RI watersheds (Connecticut River)

Coastal plain estuary 

Salinity and temperature in an estuary?

—Temporally, spatially, and vertically

—Time (temporal): seasonality, daily weather, tides

—Place (spatially): where in an estuary

—Depth (vertically)

Which is heavier?

—Salt water or fresh water

Which is heavier?

—Hot water or cold water

Salt is more dense, cold more dense

Vertical differences in estuaries are based on:

—densities of water input

—speed of water input

—Circulation depth of estuary

Are estuaries classified by how fresh and salt water mix?

Yes

Salt wedge: River>>Tidal currents

Partially mixed / slightly stratified: deep, River>Tidal current

Well mixed/ vertically mixed: shallow, River<Tidal currents

Inverse: River<<Tidal currents; salinity in estuary higher than the ocean, typically found in very dry climates

Why were hydrothermal vents such a paradigm-shifting discovery?

• extremeophiles, lots of life living under extreme conditions

• autotrophs using things other than sunlight

Apart from a lack of primary productivity, what other deep sea challenges are mitigated by hydrothermal vents and methane seeps?

• finding mates, serves as a central meeting point 

• hard substrate 

• easier to find foof (org gathering producing larvae, larvae can be filter fed)

•The physical characteristics of an estuary define the communities that live there T or F

True

What is one of the greatest challenges that estuarine organisms need to adapt to in order to live in an estuary?

• changes in salinity 

Diff types of organisms by ability to handle salt

•Euryhaline (wide range of salinity)

•Stenohaline (narrow range of salinity) 

•Osmoconformers (have same salinity as environment: jellyfish)

•Osmoregulators: can be less salty than environment, can regulate salt

Types of osmoregulators: Anadromous = go from fresh to salty, salmon Catadromous = go from salty to fresh, eel 

Why anadromous and catadromous? Latitudinal trends: WHy might they have evolved?

A = Strategy more common in higher latitude, open ocean more productive 

C = more common in lower latitude, because avoiding predation (more prodcutve place is freshwater) 

Makes sense to breed in area where other members of the same speices are and where larvae can survive 

Different species adapt and handle salinity differently, T or F

True, estuaries have salinity gradients and zonation from these gradients

What estuarine species live with salt through osmoregulation? Trhough movement/life cycles and locations? 

•Through osmoregulation: Fish and marine inverts, Sharks, birds, reptiles have salt glands

•Through movement: Life cycles and locations (A vs. C) 

Challenges estuaries face from humans:

•Coastal development: Increasing human population and Cities fitting more people in a small space

•Pollution: Nonpoint sources, Point sources

•Climate Change

How are estuaries changing due to climate change:

Temp: phenology (changing of the seasons, climate change will alter behavior of org that responds to changes in season based on temp), but not to org that respond to daylight (Physiology and behavior changes)

Ocean acidification: shell making becomes more costly in acidic oceans

Rising sea levels: Saltmarshes/ wetlands/ coastal habitats
getting inundated, Not keeping up with
sea level rise (RAE, Climate Central, NERRA)

Sandy shores: particle size influences water retention

small particle = inc water retention, burrowing into the sediment

•Wave action & its effect on sediment particle size

•Particle size influences water retention & burrowing into the sediment

•Organisms in fine-sand sediment are less subject to desiccation than organisms in coarse-gravel beach

•Wave action creates unstable, constantly moving substrate on open sand beaches

Comparison of the physical conditions found on fine-grained and coarse-grained beaches

Adaptations of organisms to sandy shores

•Adaptations to unstable substrate

•Burrow deeply into the substrate below the depth of sediment affected by the passing wave (e.g. Large clams such as Tivella stultorum)

•Burrow very quickly as soon as the passing wave has removed the animal from the substrate (e.g. many annelid worms, small clams, crustaceans)

•May also burrow to anchor and filter feed.

Open sand beaches: types of organisms

•No large plants on open sand beaches

•Primary producers are certain benthic diatoms & various phytoplankton living in the surf; protected sand flats support diverse flora of benthic diatoms, dinoflagellates, cyanobacteria

•Sessile animals such as barnacles, mussels are absent

•Dominated by polychaete worms, bivalve mollusks, crustaceans

Feeding biology of organisms on sandy beaches 

•Animals on sandy beaches depend on phytoplankton from seawater, organic debris brought in by waves or other beach animals

•Invertebrates on open sand beaches dominated by filter feeders (e.g. surf clam), detritus feeders (e.g. polychaetes, sand dollars), scavengers

•Protected sand flats: microflora films, seagrasses, ephemeral macroalgae

•Predators include shorebirds (at low tide), fishes (at high tide)

Generalized pattern of distribution of organisms on sandy beaches

Supra = driest part

•Dominated by deposit feeders

•Main biological factors that structure sand flat communities are: predation or predation combined with disturbance; competition may may be less important

Ex. of predators having impact in sand flats

•Moon snails (Polinices sp.) prey on bivalves

•Large crabs (blue crab, green crab) dig into the sediment to locate prey

•Horseshoe crab (Limulus), seasonal predator that dig into sediment searching for infauna

•Whelks (Busycon, Thais spp.)

COMPETITION LESS IMPORTANT FOR ZONATION, predation has higher impact

Muddy shores physical factors

•Slopes are much flatter than those of sandy beaches, hence muddy shores are known as mudflats

•Muddy shores are more stable than sandy substrates; more permanent burrows could be established

•High water retention; oxygen depletion below  the 1^st few cms of the sediment (anaerobic condition)

Adaptations of organisms to muddy shores

•Most organisms in this area are adapted to burrowing or inhabit permanent tubes in the substrate

•Adapted to live under anaerobic conditions or must have some way of bringing the overlying surface water with its oxygen supply down to them

•Adaptations to live at low oxygen tensions: hemoglobin; use of glycogen stores for anaerobic metabolism when O2 is little or unavailable

What faunal differences do you expect between sandy shores and muddy shores?

Stable tunnels, burrows to bring water down to anoxic later in muddy (relatively stable) 

Why do estuaries face particular challenges due to human impacts? 

Human dev, interface btwn ocean river land, overfishing, pollutants from river (terrestrial nutrient input but also toxic stuff like pesticides) 

What is a coral?

niderians

have nematocysts (stinging structure to capture prey/food or for defense)

within coral are photosynthetic algae 

corals are heterotrophic but gets products of photosynthesis from algae and give algae place to survive 

Hermatypic (reef building corals) have what ….

zooxanthellae (ALGAE) , need symbiosis with algae, laying down calculumcarbonate skeleton as they grow (need energy) 

Do coral reefs make up a large percentage of planet, are they well described, do they help with carbon?

•Cover 0.71% of area of planet

•~1 million species, only 100,000 described

•Remove ~700 billion kg of C/yr

What are the conditions for coral reef growth?

Water temp = 18-40C WARM

Light requirements : to 1% surface intensity ~70m depth

Salinity: 32-35 psu

Low sediment (can’t tolerate sediment)

Short (<1hr) emersion (can’t handle intertidal zone well)

Moderate-high water motion

Coral world wide distribution. Where and why? 

Located in tropics, near equator. Pacific split before others, had more time to accumulate species and undergo extinction 

4 diff types of reefs

Rangiroa Reef: What makes a healthy reef?

Lots of diff species together and wide range of sizes

Clear water (low productivity in water column) 

Rangiroa Reef: What are the primary threats to coral reefs?

Climate change = coral bleaching, water more acidic, sea level rise, intense storms. 

Crown of thorns sea stars (invasive species) 

Rangiroa Reef: What are the primary tools/methods researchers use to study reefs?

Types of fish present in a radius, bethic surveys at diff depths, coral identification and what size it is/how healthy it is, collect sediment samples 

Rangiroa Reef: Advantages/disadvantages of private funding?

Advantage: Get good quality equipment

Disadvantage: Biases 

How do corals thrive despite oligotrophic conditions?

Corals thrive in nutrient-poor (oligotrophic) waters through a symbiotic relationship with algae called zooxanthellae, which live within their tissues. This partnership allows corals to efficiently recycle nutrients, and the algae provide the coral with energy from photosynthesis, while the coral host provides the algae with essential nutrients by recycling waste

Spur and groove architecture

Wvaes carrying sand and sediment over the reef, creates grooves btwn reefs that are all sand 

Zonation of corals

farther off shore and deeper

Coral trends in diversity

Low diversity at high depths (wave energy, intense conditions, very few species can handle conditions) 

Low diveristy at low depths (light limitation, comp for space, very few species) 

Intermediate diversity at medium depths 

Structure provides protection

Why do we care about reefs? Biodiversity

Reefs contain a large number of the world’s species (some estimates are >million)

Why do we care about reefs? Food

They are important sources of sustenance for populations adjacent to reefs.

Why do we care about reefs? Economics 

Some economies rely primarily on reef-related tourism  ($$)

Why do we care about reefs? Protection 

Prevent storm-driven wave energy from reaching coastal habitats (ecosystem services).

Why do we care about reefs? Nurseries

Reefs and the coastal zones they protect are important nursery habitats for commercial important species

Major players of coral reefs? 

Primary Producers (algae, corals)

Herbivores (fish, urchins)

Corallivores (fish, urchins)

Filter Feeders (sponges, tunnicates)

Suspension Feeders (corals, sea stars)

Deposit Feeders (sea cucumber)

Predators (fish)

Bioeroders what are they and why are they an issue? 

Coral tissue or algae embedded in coral skeleton. Problem because coral provides structure to support biodiversity, so eating corals = erodes it into rubble 

Competition among corals. Why?

Competing for space to get light due to limited substratum

Ex. comp reduces ability to grow/offspring in stony corals

Tabular morphologies limit competitors - what did Bair and Hughes find? 

Recruitment was limited in the acropora understory on the GBR 

Limitation is attributable to low light/habitat suitability and not larval supply 

How frequent is competition?

Connell (1976) found 82 competitive interactions between twelve species of corals in ONE square meter on Heron Island, GBR

What role does competition play? COMPLICATED/IT DEPENDS 

Variations in environmental conditions, habitat, colony sizes and positions etc. make it difficult to predict community structure from simple competitive interactions

e.g., there are often different winners under different conditions

What did Lang propose about competitve hierarchies vs. Buss and Jackson? 

Lang (1973) proposed that corals can be arranged into hierarchies based on competitive interactions

i.e., A<B<C

Buss and Jackson (1979) suggest that competitive relationships are networks rather than hierarchies

i.e., A<B<C but C<A

Networks change with environmental conditions

One coral could be the clear champion and is the best competitor, but is nearly absent, why?

Sucks at everything else. Investing a lot of energy in ability to compete not larvae and growth 

What is competition network? Why not hierarchy?

Who survives in based on what it is next to, this explains high biodiversity of corals 

Do algae have faster growth rates and how do they response to nutrients?

Faster growth rates

Faster growth response to available nutrients

Are algae outcompeting corals?

Probably not. Corals are likely to be killed by numerous other stressors and algae quickly use the open space. 

corals are killed, algae are there to take over:

coral dec → crown of thorns (eat coral) inc → algae inc → fish inc (eat algae) → algae dec → coral grows back

On some reefs, we see a lot of macroalgae instead of living coral. Does algae outcompete and kill coral?

No, coral dies from various factors, algae uses that space. Coral does not come back because nutrient input may be providing stuff for algae, when coral try to settle back the algae are in the way, not enough herbivorous fish to control algae (climate change, overfishing)

Why do reefs form “spur and groove” architecture?

Drainage channels, water and sand has got to go somewhwere, coral won’t grow there

As corals are killed by disease and bleaching, why are we concerned about bioeroders? What are some bioeroders?

Taking away physical structure, turned into rubble field. parrot fish, sea urchins

Feeding preference - what happens to corals neighboring acropora

Corals neighboring acroporia will be eaten by starfish

Positive interactions: when are they more important? What are the types in ocean:

Tend to be important in stressful or resource limited environment (deep ocean: nutrient poor, dense with predators)

Mutualism/Commensalism (Coral Crab Mutualism)

Facilitation:

• Generation of habitat

• Availability of resources

• Refuge from predation

Coral as facilitators what do they do?

• provide habitat/refuge from predators

• things can grow on and in the coral

• calcium carbonate = hard substratum

• lots of niches (cryptic, coelobitic, low flow, high flow, low light, high light)

• suitable settlement space for sessile invertebrates

• fix carbon and exude mucus which can be consumed or attract bacteria which can then be consumed

Why is there a positive relationship between coral species richness and estimated invertebrate richness?

more richness = more niches (can have big coral, small coral, each which attract diff types of invertebrates)

Coral-crab mutualism

Crabs use corals as a refuge from predators and a source of food

coral provides mucus that crabs benefit from, crabs remove algae from coral

only happens in high light conditions because there is more light energy to make mucus and more light for algae to grow

Without crabs what are the trends of coral mortality, growth, and bleaching?

Mortality = high

Growth = low

Bleach = high

Shows that there is coral/crab mutualism where corals need crabs to survive

Sponge/sponge mutualisms: why do they need each other and what do they do to help each other?

Sponges are susceptible to predation and storm-induced breakage

Sponge species have differing chemical defense, tissue density, spicule structure etc

sponge is next to a diff type of sponge that doesn’t taste very good so predators will also avoid sponge 1 (sponges growing next to dissimilar sponges = benefits)

Vermetid gastropods where have they increased in density? What do they do to corals?

Eliat (Red Sea)

Gastropods extend mucus net to get food, the mucus overlaying the corals then changes their morphology which impacts their ability to survive (ex. ability to gather light, food)

As you get farther away from gastropod = morphology ok

close to gastropod = wide range of morphological differences

What are the main threats to coral reefs on global, regional, and local scales?

Global: warming, bleaching (takes more energy to make good skeleton), acidification

Regional: disease outbreaks (ex. stony coral tissue loss outbreak)

Local: overfishing, sediment/agricultural runoff