marine ecology quiz 2 (rocky and sandy shores)

basin mangroves

* large areas behind riverine and fringe mangals
* least productive
* rarely flooded, low tidal/wave action
* salinity highly variable

hypo osmotic

lose water via osmosis

littoral zone of rocky and sandy shores

only part of marine environment that faces regular exposure to air (emersion)

large particles

* stable substrate for attachment
* support epifauna and flora

fina particle sands

* too unstable for surface attachment
* support meiofauna and infauna

intermediate particles

* don’t support microbiota
* spaces too big to hide, particles too small for attachment

rocky shores

* occur on steep coasts with minimal amounts of sediment
* recently uplifted or still rising

where do rocky shores form

* west coast where active margins have been uplifted
* eastern Canada and New England melting of glaciers

sandy shores

* gently sloping coasts with abundant sediment
* southern Atlantic and gulf coasts along passive margins

upper limit of rocky shore zones determined by

physical factors

lower limit of rocky shore zones determined by

biological factors

extensive wave action

can wash away sediment resulting in rocky shores

species living in shore communities must be able to tolerate

changes in

* moisture
* wave action
* salinity
* temperature

species with exposure at low tide

* prevent or tolerate desiccation from emersion
* move, hide, use protective coverings
* tolerate wide range of temperatures

wave shock

* force of striking waves
* strongly affects intertidal organisms

characteristics that help tp resist wave shock

* firmly secure themselves
* find shelter (trade of of moving fast/holding tight)
* low profile/compact shape (barnacles, limpets)
* soft bodies or hard shells

organisms that secure themselves during high wave activity

* seaweed: holdfasts
* mussels: byssal threads
* gobi fish: modified fins

waves created when

wind drags across water taking surface layer with it

supra tidal (supralittoral) zone

* only submerged at extreme high tides
* species must be well adapted to emersion
* wave splash provides moisture to area

organisms within supra tidal zones

* lichens
* limits green, brown, red algae in moist spots
* air-breathing isopods/amphipods at times
* periwinkles and limpets
* occasional shore crab or land predator

intertidal (littoral) zone

* regularly submerged and uncovered by tides
* upper, middle, lower intertidal

variation in tide heights

* produce variation in emersion times
* results in vertical zonation within intertidal zone

zonation patterns

result from combination of

* larval settlement
* tolerance to desiccation
* competition and predation

lower intertidal

* submerged most of day

organisms of lower intertidal

* dog whelks/sea stars dominate mussel populations
* red, green, brown seaweeds that can’t tolerate emersion (high growth rates)
* urchins, sea anemones, snails, sea slugs, fishes, crabs

upper tidal organisms

* barnacles
* lichens
* periwinkles
* limpets
* encrusting algae

organisms of middle intertidal

* mussels
* gooseneck barnacles
* brown seaweed

grazing and competition for light/space

* important
* ex:green and red algae

least likely to find keystone species in

* tropical intertidal zones
* temperate estuaries
* sandy shores

recruitment strength of dominant competitor

can lead to competitive exclusion of inferior competitors

soft bottom systems (sandy shores)

* found where sediment accumulates
* unstable ad shift with tides

zonation patterns difficult to observe in soft bottom communities

* have to disturb habitat to manipulate or observe
* 3 dimensional environment with horizontal and vertical zonation

living in the sediment

* desiccation not usually an issue
* detritus main food source
* deposit feeders extract organic matter from sediments

grain size affects oxygen availability

* infauna depend on circulation of water
* must adapt to oxygen shortages
* many species pump water from surface via siphons or through burrows

bioturbators

* species who live in, move through, ingest and egest sediment
* draw water down from surface

organisms of sandy shores

* clams
* cockles
* sand crabs
* ghost/mud shrimp
* sand dollars

human impacts on sandy shores

* accelerated sea level rise
* urbanization along coastlines

estuary

* inlet of sea reaching into a valley as far as the upper limit tidal rise
* usually divisible into three sectors

lower estuary sector

* free connection with open sea
* dilution of sea water no longer measurable

middle estuary sector

* characterized by mudflats and low tides
* subject to strong salt and freshwater mixing

upper estuary sector

* spatially fixed, upper limit of tidal influence
* characterized by freshwater but subject to daily tidal action
* coastal salt marshes and mangroves

estuary head

* dominated by river flow
*

upper reaches

* main area of mixing for FW and SW
* salinity high and variable
* current negligible
* fine, muddy sediment

middle reaches

* flow dominated by tidal currents
* salinity 18-25 psu
* extensive intertidal flats mainly muddy but increasing sand content

lower reaches

* faster tidal currents
* salinity 25-34 psu
* sediment mainly sand

mouth

* estuary meets ocean
* strong tidal currents
* salinity >35 psu
* clean sand, shell fragments or rocks
* dominated by marine species
* bivalve beds common

coral plain estuaries

* most common type
* result of flooding in low land areas when sea levels rose at last ice age
* Chesapeake bay, mouth of Delaware river

Fjords

* u-shaped valleys created by retreating glaciers
* flooded when sea level rose
* eastern Alaska, Norway, Greenland
* limited diversity

sill

* at mouth of fjords
* limits exchange with SW resulting in low oxygen or anoxic deeper waters

Bar-built estuaries

* accumulation of sediment along coasts from barter islands or sand bars
* texas gulf coast, outer banks

tectonic estuaries

* form when the land subsides due to tectonic activity
* San Francisco Bay

tidal range

* key factor in dynamics and ecology of an estuary
* affects various physiochemical parameters that affect organisms function, survival, and distribution

micro tidal

range of less than 2 m

mesotidal

range between 2 and 4 m

macro tidal

range between 4 and 6 m

hypertidal

tidal range greater than 6 m

Salinity

* fluctuates longitudinally, hourly, seasonally, and with depth in middle of estuary

what influences distribution of salinity

* shape of estuary
* its bottom
* wind
* evaporation
* seasonal variation in surface runoff
* changes in tides

what impacts salinity longitudinally and with depth

volume & flow rate of SW and FW moving in opposite directions

salt wedge effect

limited mixing in middle reaches

two layer flow

* low salinity at surface
* higher salinity at depth

well mixed estuary

even salinity

sand and coarse sediment

settles into the upper reaches

fine particulates and silt

* carried further
* most settling out in mid-reaches forming mudflats

sediment

* extensive in estuaries with large tidal ranges & gentle sloping bottoms
* rich in organic matter but difficult to colonize

interstitial water

* water btw sediment particles
* often anoxic below first few cm of depth

anaerobic bacteria

* abundant in mudflats
* black color
* hydrogen sulfide smell

aerobic bacteria

* dominate decomposition of organic material in estuaries
* use up lots of oxygen via aerobic respiration

O2 levels

* normal at mouth and head of estuary

DO sag mid estuary

due to bacterial action within mudflats

temperature

* varies in estuaries (except fjords) because shallow depth and large surface area
* dominant factor in fish abundance in estuaries

warmer temps

* increase microbial action (tropics/summer)
* DO sags more prominent

poikilotherm

* thermal conformers
* allow body temp to adjust width external temp

standard performance curves show

* increase in performance below the optimum
* an optimum with maximized performance
* decline in performance at temps higher than optimum

at or above critical thermal maximum

* individual may lose ability to move or function

key to survival in estuary

ability to tolerate salinity

euryhaline

* tolerates large range of salinities

stenohaline

tolerate narrow range of salinities

osmosis

passive movement of water from region of high water concentration to region of low concentration

hyper osmotic

gain water via osmosis

isosmotic

no net water flux

osmoconformeers

allow osmolarity of body fluids to change with environmental changes

animals can adapt to changes in behavior

* closing shell
* burrowing mud
* swimming away

osmoregulators

maintain slat/fluid balance of their body regardless of environmental changes

most marine vertebrates

hypo osmotic to sea water

many crustaceans

* excellent regulators
* some species osmoregulate at lower salinities and osmoconform at higher salinities

ecological significance of estuaries

* buffer zones, protecting lands from crashing waves and storms and helping erosion
* filter out sediment and pollutants from terrestrial sources
* feeding/nursery habitats for fish, invertebrates, and migratory birds

sedimentation restricts light penetration

* cam limit primary productivity, even when density of phytoplankton is high

fish in estuaries

* rich variety
* many dependent on estuary for reproduction
* exploit food availability in form of infauna and mobile invertebrates

juveniles of many marine species

* use estuaries as nurseries
* abundant food, hiding places and warmer temperatures

anadromous

* sea water origin
* salmon, smelt, shads

catadromous

* freshwater origin
* freshwater eel

estuarine specialist

* spend entire life cycle in estuary
* killifish

infuana

* dominant animals of mudflats
* feed on detritus
* bivalves, grass shrimp, ghost shrimp

meiofauna

* live in interstitial water


* protozoans, nematodes


* most deposit feeders

epifauna

* live on mud


* mud snails, amphipods, some crabs and shrimp

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mudflats

* formed when fine particles and silt settle out

birds and estuaries

* migratory stopovers
* birds predators of mudflats (bioturbators)
* feed on all trophic levels invertebrates
* size of estuary and density of prey affect bird distributions

ideal free distribution

* birds choose to forage in patches where food intake is greatest
* no impediments to movement or foraging
* bird utopia

ideal despotic distribution

* territoriality impedes movement and foraging of birds
* influences distribution