EMES 442/BIOL 457 Final Exam Spring 2025

Benthos

animals and plants associated with the seafloor

Plankton

organisms that live suspended in the water (may have some ability to move but cannot counteract ocean currents or turbulence)

Nekton

free-swimming animals that can move throughout the water column

Epifaunal

organisms living on the seabed surface

Infaunal

organisms that can burrow within the soft seabed

Neuston

organisms associated with the sea surface (including microorganisms)

Intertidal

ranges of depths between highest/lowest extent of the tides

subtidal

entire remainder of the sea from low water tidemark to greatest depth of the ocean

Neritic

(aka continental shelf) includes all seafloor and open water habitats between the high water mark and the shelf edge

Epipelagic

the surface layer or sunlight layer of the ocean (upper 200 m)

Mesopelagic

200-1000m, twilight zone

Bathypelagic

1000-4000m

Abyssopelagic

4000-6000m

Hadal

Below 6000m

Deep sea

the marine environment that lies below the light level necessary for photosynthesis, exclusive of continental shelves

Aphotic zone

Layer of ocean that receives no light (95% of total ocean volume)

Species richness

the number of species in a given area

Photic zone

sunlight ocean layer near the surface of water (5% of total ocean volume)

Southern ocean

body of water surrounding Antarctica

Coriolis effect

a phenomenon that causes fluids, like water and air, to curve as they travel across or above Earth's surface

Ekman transport

net motion of fluid as the result of Coriolis and turbulent drag forces

zooplankton

small free-floating eukaryotes (protists and animals)

meroplankton

organisms that spend part of their time in the water column but also spend time in the benthos

holoplankton

organisms that spend all their life in the water column and not on/in the seabed

icthyoplankton

the eggs and larvae of fish

planktotrophic

feed in plankton stage, spend 10-40 days in plankton stage, small/many eggs per spawn, better dispersal

lecithotrophic

use egg sac for nourishment, large/fewer eggs per spawn, spend 0-5 days in plankton stage, poorer dispersal

keystone predator

a predator that reduces the density of the strongest competitors in a community, helps maintain species diversity

keystone species

a species on which other species in an ecosystem largely depend (if it were removed the ecosystem would change drastically)

chemosynthesis

process by which a living organism harnesses energy from chemical processes to make sugars

deposit feeder

feeding on particulate organic matter that settles on the seafloor

suspension feeder

feeding on particulate organic matter suspended in the water

motile benthic

benthic organsim that can move, macrobenthos

macrobenthos

animals > 0.5 mm, epifaunal and infaunal

meiobenthos

animals< 0.5 mm (all infaunal)

upwelling

upward movement of cold, nutrient rich water from the deep to surface

wave action

movement of waves in an area, strong wave action

tidal mixing

1. Gravitational pull of moon and sun in same plane: spring tides

2. Gravitational pull of moon and sun perpendicular: neap tides

types of estuarine circulation

salt wedge, partially mixed, well mixed

ecosystem engineer

an organism that can create or modify habitats for other species

Laminaria

brown algae commonly found in kelp ecosystems

Hermatypic corals

corals that build with CaCO3

Ahermatypic corals

corals that do not build with CaCO3

Mounding corals

hermatypic coral, mound-shaped, grows slowly (ex- Siderastrea sp.)

Branching corals

hermatypic corals, tree-like/elkhorn shape, grows rapidly (ex- Acropora sp.)

Mesenterial filaments

filaments of coral used for defense and competition

Symbiodinium

photosynthetic dinoflagellate symbiont of coral (coral-zooxanthellae symbiosis) and other marine hosts, nine major clades with sub-clades

gastrodermis

cells lining the interior of polyp, serves as digestive system of the coral

endosymbiont

microbial symbiont that livies within its host

ectosymbiont

microbial symbiont located on the surface of its host

biodiversity

the variety of life, at all levels of organization, classified both by evolutionary and ecological criteria

trophosome

"feeding body" of Riftia tube worms, location of chemosynthetic bacteria

seamounts

isolated elevated areas, usually of volcanic origin, found through all oceans (but mostly near oceanic island arcs and mid-oceanic ridges), have hard substrata on top

Lophelia

deep sea coral community, slow growing stony coral, no photosynthetic symbionts

counterillumination

bioluminescence that allows organism to camoflauge by matching the light from above (ex- hatchetfish)

mudflats

form in sheltered areas of the coast where large quantities of silt are deposited, sediment is stable and community has high biomass of invertebrates

sandy beaches

occur where wave action or strong tides prevent silt deposition (open coast beaches/bays), mobility of sediment limits the species that can inhabit it, inhabitants are robust including amphipod crustaceans

rocky intertidal zones

located on active margins, intertidal habitats have distinct vertical zonation where dominant species occur in distinct horizontal bands

succession

replacement of organisms through time

invasion

human-aided transport of species, occurs by ship travel, aquaculture, ballast water

inhibition

process where one species limits activity/establishment of another

Tolerance

range of conditions an organism can withstand

facilitation

occurs when the presence of one species permits the establishment of another

stilt roots

support trunk of mangrove tree

prop roots

provide stability to mangrove tree

plank roots

Vertical structure of roots thought to help with aeration and snaking horizontal expansion provides stability in sediment

pneumatophores

roots that allow for oxygen uptake and can protect soil from wave action, grow in response to soil anoxia

anoxia

absence of oxygen

nursery grounds

habitats that are particularly suitable for juvenile species to grow

coastal plain estuary

formed at end of last ice age, when rising seas invaded low-lying coastal river valleys

bar-built estuary

formed as sandbars build up along the coastline , partially cutting off the waters behind them from the sea

tectonic estuary

created when the sea fills in the "hole" or basin that was formed by the sinking land from plate movement

fjords

valleys that have been cut deeper by moving glaciers and then invaded by the sea

salt-wedge estuary

where a river discharges into a virtually tideless sea

partially-mixed estuary

occurs where rivers discharge into a sea with a moderate tidal range

well-mixed estuary

Broad, shallow, estuaries where the tidal range is high, and the tidal currents are strong relative to the river flow

residual circulation

The mixing of seawater and river water as it meets in an estuary. For salt wedge and partially mixed estuaries the residual circulation is vertical, for well-mixed estuaries the residual circulation is horizontal, due to Coriolis effect.

two-phase life history

life cycle is in two distinct stages, can be separated by location

Zostera (eelgrass)

common in temperate zones

Thalassia (turtle grass)

common in tropics

Labyrinthula (wasting disease)

pathogenic protist, secondary decomposer that affects old leaves, infection linked to stressed eelgrass (healthy tissue can resist infection)

wasting disease

seagrass diseases causing near-collapse of Zostera and its associated animals, erosion of soft sediments

Elkhorn and staghorn corals

key coral species in the Caribbean and Florida for shallow reef building

hybridization

occurs when egg of one species is fertilized by sperm of another

spawning

release of eggs and sperm into the surrounding water

asexual reproduction

in corals- occurs by division of polyps in large areas of reef being covered with a single genotype

photosynthesis vs chemosynthesis

photosynthesis uses sunlight as its energy source, chemosynthesis uses chemicals as energy source, both produce organic carbon as an end product

characteristics of marine macroalgae found in kelp habitats and what restricts their growth

Fast growing, require clear water, hard substrate, high nutrients, lower water temps. Warmer temps, sediment loading, and reduced nutrients (ex. from lack of upwelling) can restrict growth

passive vs active margins

passive: sandy shoreline with gentle slopes

active: rocky shorelines with steep depths

relationship between temperature, salinity, and seawater density

density increases with increasing salinity and decreasing temperature

thermohaline circulation

Facilitated by ice formation at the poles and drives deep sea currents in the global conveyor belt

common/scientific names of two types of sea grasses and primary consumers

Sea grasses: Thalassia (turtle grass), Zostera (eelgrass)

Grazers: Dugongs, Manatees, Green Sea Turtles

Food webs of Arctic and Antarctic and animals found in one or both ecosystems

Arctic food web: ice algae -> zooplankton (copepods) -> jellyfish -> arctic cod -> seals -> polar bear. Also, benthic inverts -> walrus -> polar bears (sometimes). Polar bear is apex predator

Antarctic food web: algae -> zooplankton (krill) -> squids and fish -> seals -> orca. Also, krill/fish -> penguins -> leopard seals. Orcas are apex predator

penguins belong to which order

Sphenisciformes

example of keystone species discussed in class

Krill are a keystone species in the Antarctic: penguins, petrel, herrings, anchovies, squid, seals depend on krill as a food source

Factors that change with increasing depth

decreasing light, increasing pressure, decreasing temperature, decreasing food availability, decreasing oxygen levels

calculations of pressure (in atm) at a given depth

pressure (atm) = (depth in meters/10) + 1

Habitat, symbiosis, and metabolism of Riftia tube worms

habitat: hydrothermal vent communities

symbiosis/metabolism: chemosynthetic bacteria inhabit trophosome and release carbohydrates for the Riftia to metabolize

characteristics of seamounts

rise more than 1km off the seafloor, have hard substrata on top because deep-sea currents prevent sediment from settling (making it a great location for invertebrate larvae to settle)

organisms found at specific intertidal zones along the rocky shore

lower intertidal: seaweeds, surf grass, anemones, sea stars

middle intertidal: mussels, barnacles

upper intertidal: periwinkles, limpets, lichens, encrusting algae