Marine Ecology Exam 4

Coral reef

large, wave resistant structure accumulated from slow growth of corals and coralline algae

Coral distribution and biogeography

concentrated on the equator with high species richness in the coral triangle

Factors limiting reef growth

High temperature, high light, basic pH, open marine salinities, low turbidity

Coral reef form diversity

large number of closely related species with strong phenotypic plasticity

What factors are coral phenotypic plasticity dependant on

flow and depth

Corals further from coasts are ___, corals close to coast are ___ to be resistant to high energy waves

branched/plated; flat and robust

Fringing reef

close to land with little to no intervening lagoon, well-illuminated, shallow water. border shorelines of continents and islands

Barrier reef

Large lagoon between island and reed due to volcano movement, erosion, and coastal subsidence

Atoll reef

open ocean stucture away from coast. Lagoon is most prominent feature as volcanic island has sunken

Hermatypic corals

reef framework building, have many zooxanthellae, high calcification, colonies of similar polyps, divided into branching and massive forms

Ahermatypic corals

not framework builders, low calcification

Hermatypic phylogeny

Phylum Cnidaria, Class Anthozoa, Order Scleractinia

Branching hermatypic growth

grow in linear dimension fairly rapidly, 20cm per year

Massive hermatypic growth

produce lots of calcium carbonate but grow more slowly in linear dimensions, about 1 cm per year

Zooxanthellae

photosynthetic dinoflagellates found in multiple species. Holobionts

Holobionts

interactive assemblages of species that form ecological units

Symbiotic benefits to coral

provides nutrients, facilitate calcification- increasing pH, sequester toxic compounds by algae

Symbiotic benefits to zooxanthellae

protection from UV damage, stable substrate and nutrients

Why do corals host so many species

greater area, climate stability reduces extinction rates, fragmented nature of island studded archipelagos, faster demographic rates at higher temperatures leading to higher speciation, 

How does coral reef island studded achipelagos increase diversity

provide 3D habitat which drives regional diversity, increasing habitat thru reef growth allows more species to thrive, “islands” of reef have different environmental conditions which leads to genetic drift

Ultimate niche partitioning

similar species divide resources to reduce competition- seen heavily in coral reefs

Reef fish diversity

Hebivores dominate, reef fish and selective and specialized feeders, fish and urchins consume about 100% of daily reef production

Grazers

consume epilithic algal matrix from substrate. maintain successional community and prevents growth of upright macroalgae. maintains coral dominance from coral-algal shift

Browers

consume large, established macroalgae

Coral-Algal phase shift

significant change in the reef’s composition. Alternate stable state typically algal barren

Coral dominated system (phase shift)

3D space to provide shelter, fish and urchins graze algae,  fish and urchins keep space clear for new coral polyps to settle and grow

Algal dominated system (phase shift)

absense of fish and urchins because of lack of habitat. Algae outcompete coral polyps for space of seafloor

How do human pressures impact coral-algal phase shift

algae get competitive edge. overfishing, nutrient inputs, disease, and warming and acidification are all anthropogenic and harmful for corals

Alternate states of coral-algal phase shift

overfishing of echinoid predators can lead to sea urchin barren state, then rock state

Coral biological interactions

endosymbiosis, predation and grazing, competition, disturbance, larval recruitment, disease

Coral bleaching

expulsion of zooxanthellae from stress (temp, disease) mechanisms are poorly understood. zooxanthellae cells appear to die and be expelled.

Mass spawning

Corals on GBR and texas spawn at same time once a year at night likely to avoid predation. Most corals have planktonic gametes

Coral competition

shading, overgrowth, interspecific digestion, sweeper tentacles, allelopathy

Speciation

group of within a species seperates from other members in species and develops unique characteristics

Allopatric speciation

origin of species as a result of seperation by extrinsic barriers

Peripatric speciation

small group of individuals breaks off to form a new species

Parapatric speciation

species spread out over a large geographical area, resulting in mating with individuals in their immediate vicinity

Sympatric speciation

no geographic barrier, but gene flow restricted in another way

What extrinsic factors influence speciation rates

habitat age, habitat area/geographic range, temperature

species-energy hypothesis

species richness is higher in habitats that recieve more of the energy needed to power metabolism

What intrinsic factors influence speciation rate

body size, life history and dispersal ability, resource specialization

Polar productivity characteristics

seasonally light limited, not nutrient limited, no thermal stratification

Artic ocean

semi-enclosed sea, wide continental shelves, central deep water isolated, significant river input, permanent pack ice

Antarctic

deep ocean ring around continental land mass, no river input, mostly temporary pack ice, strong surrounding currents

Antartic chlorophyll concentration origins

upwelling

Arctic chlorophyll concentration origins

river input, nutrients, stratification

Arctic food web structure

fish based

Antarctic food web structure

krill based

Pack ice

mixture of ice crystals and brine chanels

Krill (Euphausiids) v. Salps in antarctic

Planktonic grazer, high interannual variation: Krill high ice, Salps low ice

Coupling

important in Antartic between Benthic-Pelagic communities

Arctic Benthos

live in soft sediment, distubance dominated from N. Atlantic

Antarctic Benthos

live in hard bottom with minor soft bottom, physical disturbance, high endemism

Polar disturbances

waves, ice scours, salinity variation, macrofauna

Antarctic zonation

zone 1 (persistent ice-scour) zone 2 (anchor ice) zone 3 (stable, predator dominated)

Polar gigantism hypothesese

oxygen availability, silica chemistry, carbonate chemistry, biogeographic and ecological (monsters from the deep)

Fluctuations

regular, cyclic changes

Disturbances

a discrete event in time that disrupts ecosystem, community, or population structure and changes resources, substratum, or the physical environment

Natural disturbances in the marine environment

weather, sediment processes, harmful algal blooms, anoxic/hypoxic events, disease, variable recruitment leading to high/low abundance of key organisms

Weather natural disturbances

storm waves, el nino/la nina, hyper/hyop salinity, extreme hot and cold events, ice scour

Anthropogenic disturbances in the marine environment

Direct physical disturbances to habitats, overfishing, climate change and acidification, pollution/eutrophication

What marine ecosystems are frequently disturbed

shallow water/intertidal environments, estuaries, storm-exposed coasts, heavily trawled/trafficked/polluted coastal waters, shallow continental shelves in wave-exposed areas

What marine ecosystems are rarely disturbed

Deep sea environments, open ocean pelagic environments, some arctic/antarctic environments, deep seamounts

Disturbance impact on ecosystem

alters populations, communities, and physical/chemical features of the environment, typically decreases biodiversity and habitat structure initially

Resistance

how well the ecosystem resists disturbance; how little it changes from its original state

Resilience

how quickly the ecosytem returns to its original state after the disturbance

Ecosystem resistant properties

strong biogenic structures, large, healthy populations of hardy organisms, high biodiversity, including species immune to the disturbance

Ecosystem resistant properties

Quick growing, quick reproducing species, recruitment from nearby, undisturbed areas, high biodiversity, including species able to recover quickly

Succession

the process of gradual change in the species composition of an ecological community over time

Connell’s Intermediate distubance hypothesis

medium disturbance yields the highest diversity

What can predators tell us about ecosystem

production, community, evolution

How can ocean drilling tell about the future

calcareous and planktonic parts layer, then we can dtermine accumulation rates of fossils

What can we learn from ocean bottom fossils

fish in the past followed warmer temperatures

Major GHGs

Water vapor, CO2, Methane

What causes oxygen dead zones

eutrophication

How do we influence invasives

Ballast water on ships transport non-natives across sea

Global climate change CO2

CO2 increasing and flucauates with seasons in spring blooms

Ocean acidification

pH in ocean declines as ocean absorbs CO2, which is harmful to food chains and organims with calcium carbonate shells/skeletons b/c increased carbonic acid

Phenological shifts

mismatches result as species adapt at different rates to cyclic events such as plankton and fish blooms