Marine Communities exam 3
Foundation/dominant species
-some species high in abundance and have high importance -ex: Coral
Black rush
-species of flowering plant -lies along coastline of Southern U.S. and GOM
Paine's experiment results
- presence of predator permits a higher number of species to co-exist; increase in the number of prey species - this experiment was also performed in New Zealand where the community is a bit larger --Here, the top predator is the starfish Stichaster australis - We see the same basic results that were found in Washington
How are oyster reefs doing worldwide?
-85% of oyster reefs have been lost globally
Connell Study on barnacles
-Adult Semibalanus extend from mean low water to above mid tide line. Chthamalus extends from upper limit of Semibalanus to upper intertidal. -Adult barnacles do not overlap -Larval settlement overlaps --Distribution not due to larval settlement but post-settlement mortality -Transplant experiments suggest Semibalanus cannot withstand physical stress in the upper intertidal --transplanted barnacles die due to temperature or desiccation stress --he moved some rocks that were covered with Semibalanus up and they died because they could not tolerate
Why is eutrophication (excess nutrients) bad?
-Algal blooms -Hypoxia and anoxia --fatal to many benthic inverts -Increases in copepods and microzooplankton -Increase in ctenophores, jellyfish, sea nettle --not a lot of things that eat jellyfish and sea anemones
Marsh ecology: Plant zonation
-Along US east coast: --Spartina alterniflora, S. patens, Salicornia and Juncus zone along tidal creek to upland forest gradient --Inundation and elevation gradients combine with competitive differences to cause zonation -Zonation related to stress and competition: --Inundation at lower elevations causes O2 and H2S stress or toxicity --Lower limits of plants set by tolerances ---Upper elevation limited by competitive ability ---this is opposite the rocky intertidal --the most stressful region for plants is the lower intertidal --lower limits set by its tolerance --what is stressful is the lack of oxygen or the build up of hydrogen sulfides under the salt
How are plants zoned in New England salt marshes?
-Along the water edge, there is tall spartina alterniflora and then shorter spartina -after the water evaporates, the salt is left behind, stunting its growth making it shorter -Lower marshes closer to coast
Keystone species concept
-Also Paine -Keystone species influence community composition more than expected by their relative abundance or biomass -Species with low biomass but large effects on community structure -ex: Starfish -Keystone species is where a species can suppress or control an area so that the dominant species won't take over -species low in abundance but have high importance
Oyster reefs
-American oyster is a sessile, reef-building bivalve as adult -Range from Canada to GOM --local adaptations for spawning and growth -Survive and grow from 5-42‰ and can withstand a rapid 15-20‰ change -oysters reefs are another intertidal community -this one species has a huge range -survive and grow in a pretty big range of salinity --Low salinity provides a refuge from predation and disease -are osmoconformers, as salinity changes, so does their blood -very tolerant to salinity changes
Zonation in North America
-Black lichen - supra-tidal fringe -Periwinkle zone - snails in the genus Littorina. Algal scrapers --get a lot of algae and periwinkle snails in the periwinkle zone -Barnacles in the genera Semibalanus and Chthamalus in mid-intertidal Lower mid-intertidal: -Bivalves in the genus Mytilus; Suspension feeders in lower mid-intertidal -Macroalgae - kelp zone - sub-tidal fringe; Red algae and kelp (Laminaria) - can withstand only limited exposure to air
Impact of predators on macrofauna (experiment)
-Blue crab (Callinectes sapidus) and 2 bottom-feeding fishes, spot (Leiostomus xanthurus) and hogchoker (Trinectes maculatus) either excluded from or confined to small wire mesh cages -Infauna responded to decreased predation with increased density and diversity within 2 mo. -Densities of all infauna increased in exclosures, suggesting no competition -Predation pressure and sediment instability keep populations far below carrying capacity *by excluding the predators, the density of the macrofauna density increased *no competition amongst the macrofauna (prey)
appearance of salt marshes
-Broad, flat expanse of low land with grasses cut by channels leading to larger tidal creeks (bayous) -Mudflats (with benthic microalgae) interface with creeks and are exposed to air at low tide
Kelp communities
-Brown macroalgae common in temperate regions with hard bottoms -In shallow, clear (need light penetration to bottom for young kelp), nutrient-rich water -Well developed near upwellings --California has excellent kelp forests
How is intertidal soft sediments different from rocky intertidal/ RSP?
-Bury deeper in the intertidal --Lessens desiccation -Benthos can be densely packed and vertically stratified -Competition important - but mostly exploitative -Space less limiting --space isn't really limiting in this system --different from rocky shore paradigm
Connell study results
-Chthamalus lives well if transplanted down and if Semibalanus is removed --Chthamalus has refuge above Semibalanus' distributional range -Semibalanus is superior competitor for space and competition sets lower distributional limit for Chthamalus -Balunus grows real fast and crowds out Chthamalus -competitive exclusion -excludes Chthamalus from this intertidal zone -Chthamalus has a tolerance refuge from Balanus -upper limits are set by tolerance -lower limits are set by competition -lower limits of the barnacle are set by predators
The rocky subtidal and the "rocky shore paradigm"
-Competition for space is keen, and in absence of predators, monopolies are common --space is limiting -Presence of sea urchins often dictates plant community --sea urchins, a grazer of kelps, can affect that kelp community (consumer does inhibit a dominant competitor from taking over) -there is a tolerance refuge --Light related with kelp --once you get deep enough, light can determine kelp growth -Disturbance --More related to predation and smaller scale removals --disturbance can increase diversity and suppress dominant competitors --Can increase diversity, however --like the rocky shore paradigm
Explain the role of waves in the rocky shore. Impact on diversity, competition, lichen distribution, succession.
-Competition, disturbance and space use in the NW US rocky intertidal -Wave exposure, battering by logs, and desiccation affect distribution and abundance of sessile species -Wave shock enlarges patch created by log damage by wrenching mussels from substratum at periphery of bare patch --once a log smashes into a rock and forms a hole, waves continue to crash up into the hole made and make it bigger -Competition for space results in dominance of barnacles over algae. -Mytilus californianus (mussel) capable of growing over all other sessile species and is competitive dominant --Mytilus is the dominant competitor
How does meiofauna change with depth?
-Density decreases from slope to deep sea but diversity increases
Macrofauna ecology
-Deposit feeders and suspension feeders often separated -Deposit feeding is messy -May clog suspension feeding apparatus
Qualifiers in rocky intertidal
-Differences between walls and floor less pronounced at>30m, where light limits algae --greater than 30m, light is more limiting, so you get less kelps -Tropics have few kelps so not great difference between walls and floor --there are fewer kelps in the tropics
Do artificial reefs attract fish or reduce fish?
-Difficult to study because of confounding factors -Important fisheries management question -Perhaps fish are more productive near the reefs and more are produced because of the increased food supply or fish just aggregate there (by behavior) not increasing the number of fish -No definitive answer but big implications for management -production vs. attraction hypothesis
Rocky intertidal zonation
-Distinct bands of dominant species at various tidal elevation standards (e.g., mean low tide position) -relative banding zones consists of: •Supratidal •Upper intertidal -periwinkles dominant, limpets, lichens, encrusting algae also common •Mid intertidal -upper mid: barnacles dominant -lower mid: mussels, barnacles, seaweed •Lower intertidal -seaweeds, surf grass
3 Major groups of seaweeds
-Distinguished by photosynthetic pigments 1.) Green seaweed: Chlorophyta 2.) Red seaweed: Rhodophyta 3.) Brown seaweed: Phaeophyta
Fucus sp.
-Dominant seaweed in rocky intertidal -Especially Pacific Coast -have gas bladders that allow them to float when the water is high
Fiddler crabs as deposit feeders
-Fiddler crabs deposit feed on sediments in salt marshes --important deposit feeders --have an effect on meiofauna --they take mouthfuls of sediment and filter out the food particles and spit out ball of sand -Removal of fiddler crabs resulted in 10-fold increase in nematodes and meiofauna and four-fold increase in annelids ---when they removed the fiddler crabs, the meiofauna increased -deposit-feeding introduces air into marsh sediments, but does not change particle size or nutrient content -Fiddler crabs may dictate distribution of meiofauna in salt marsh habitats -secondarily reduces decomposition rates by removing meiofauna --fiddler crabs suppress meiofauna, and meiofauna are good decomposers
Meiofauna composition in New England estuaries
-From 1,184 to 5,163/10 cm2 , and wet weights from 8.5 to 62.5 mg/10 cm2 -Nematodes dominant averaging 83% of numbers and 64% of biomass. -Among nematodes, epigrowth-feeding species dominant -deposit-feeding species abundant at three stations where detritus was high
Why are seagrasses declining? (2 things)
-Globally declining at a rate of 7% annually 1.) Turbidity and epiphytic algae reduce light available to seagrasses -Eutrophication may enhance phytoplankton and epiphyte growth --Epiphytic algae blocks some of the light from reaching the seagrasses --eutrophication: having a surplus of nutrients 2.) Loss of large fish might alter food webs in a trophic cascade
Does the rocky subtidal follow the RSP?
-I do not know as of now
Does Menge and Sutherland's Consumer Stress Model apply to the rocky subtidal?
-I do not know yet
How is zonation of snails in the intertidal soft sediments similar to rocky intertidal barnacle zonation?
-I do not know yet
How does variation in salinity and predation risk affect estuarine bivalve distributions in Barataria Bay? What factors affect the distribution of oysters in estuaries? What limits them in low salinity? High salinity?
-If salinity is too low, it causes stress --Less than 5 --larvae don't do well in less than 10 and less than 2 is lethal -In higher range like 30, there are more predators and disease
How is intertidal soft sediments similar to rocky intertidal/RSP?
-Ilyanassa obsoleta dominant species -Cerithidea californica competitively inferior and restricted to upper intertidal (greater desiccation tolerance) -While phytoplankton may be homogenous (lots of mixing), benthic algae are patchy -Ilyannassa prefer areas with Ulva
Succession in rocky intertidal (Alaskan kelp forest)
-In Alaska, succession ultimately leads to Laminaria dominated community -Two different climax communities possible -Grazing by urchins causes the difference -As in the rocky intertidal, disturbance and predators can suppress the dominant competitor, allowing for other species to coexist. -Alternate steady states (climax communities)
The effect of levees and dams on subsidence
-Levees and dams have: --Reduced sediment load in the rivers --Restricted the flow out to the coast -the levees and dams confine rivers, but reduce the amount of sediment in the river
Is rocky shore paradigm widespread?
-Limiting larval supply may prevent it --few barnacles on coast of northern California because currents transport larvae elsewhere -It may or may not work in soft bottomed marine habitats (space not limiting as are two dimensional) --soft bottomed habitiat: soft sediment; space is limiting because they can dig to different depths in the sediment
Economic services of oyster reefs in LA
-Louisiana accounts for 1/3 of oysters in US -$317 million annual economic impact -4,000 jobs -One of the top two states in oyster production
Artificial reefs
-Man made structures (including oil rigs) become fouled with a wide variety of organisms -Often a good place to fish -Over 7,000 rigs in GOM (3,000 current) -Oil rigs operate for finite time period -Any structure designed to enhance existing habitat or create new habitat -enhanced local fisheries result -10% of coastline < 200 m in Japan is artificial -Artificial reefs "grow" biomass (algae and barnacles, bryozoans, corals, amphipods) that may feed fish -Reefs also provide shelter from predation -Oil rigs are artificial reefs, but not all artificial reefs are oil rigs -shipwrecks attract fish
Diversity of benthos
-Many marine species are benthic -Most animal phyla, many plants (microalgae, foliose macroalgae and seagrasses), fungi and microbes (attached to sediment particles or in pore water and more abundant than in the water column)
Describe a trophic cascade that occurs in salt marshes.
-Marsh periwinkles, Littoraria irrorata, rasp on Spartina causing fungal growth --Consume fungus. -Periwinkles consumed by mud crabs, blue crabs -periwinkles eat a fungus that grows on the Spartina -if densities of periwinkles are high enough, can actually wipe out
Trophic cascade on oyster reefs
-May compete with commensal hooked mussels --mussels tend to grow on top of oysters -Oyster toad fish --> mud crabs --> oyster spat (fish may indirectly facilitate spat) --the oyster toad fish eat mud crabs who eat oyster spat (juvenile oysters) -Most mortality of mud crabs on simple reefs is direct --"trait mediated indirect effects" occur on complex reefs --oyster toad fish lead to a decrease in oyster spat
Meiofauna ecology
-Meiofauna > 63 µm and < 0.5 mm -Interstitial in water between sand grains -25 - 40 phyla, classes and species -Vermiforms -Highest abundance/diversity in coarse sands
Positive interactions with facilitation
-More recent studies have also looked into the role of facilitation and microhabitat. -Seaweeds can reduce heat stress on molluscs -Higher latitude snails hide between rocks to stay warm
How does the vertical distribution of O2 and H2S affect infauna (both meiofauna and bacteria)?
-Most abundant and diverse in upper 4 cm --probably limited by oxygen ---there is water flowing through sands ---the meiofauna and microbes use that oxygen in the water ---the source of the oxygen is in the water above the sand ---as the sand trickles down, they use up the oxygen ---less oxygen in the bottom layers because they use the oxygen before it trickles down deep -Species often segregate vertically -Assemblage of prokaryotes and protists below deepest oxygen penetration (thiobios = sulfur) -Much deeper in sands than mud --Effect of grain size
Suspension feeding
-Most epifauna are suspension (filter) feeders when submersed -Feeding structures delicate -many infauna (clams, burrowing shrimp) capture particles from water, some live communally or secondarily in tubes and burrows -Infauna: things that live in sediment (sand and mud) --80% of sea floor
Food of meoifauna
-Most ingest bacteria, benthic microalgae or detritus -Phytodetritus= the organic particulate matter resulting from phytoplankton and other organic material in surface waters falling to the seabed -DOM or symbionts -A few are predators and eat other meoifauna
Numerical trends of meoifauna
-Nematodes first in density and diversity --most abundant and most diverse (~100 species in a sample) -copepods second (~20 species) -Density of meiofauna in mud >> sand -Species diversity of meiofauna in sand > mud --densities in mud is a lot higher than in sand but abundance a lot higher in sand than in mud
Characteristics of Salt marshes (vegetated intertidal)
-Non-tropical, associated with estuaries --don't find them as much as in the tropics -Flooded intertidal meadows dominated by halophyte grasses -Spartina alterniflora has: --aerenochyma (a soft plant tissue containing air spaces, found especially in many aquatic plants) --adventitious (shallow) roots --salt glands --high lignin content ---lignin= a tough witty component of the plant
Meiofauna and hypoxia
-On GOM continental shelf, dominant taxa were Nematoda (91.8%), Copepoda (3.2%) and Kinorhyncha (2.5%) -All taxa declined during summer in response to hypoxia --meiofauna don't like hypoxia -Copepods most dramatically impacted, effect on nematodes and kinorhynchs not as dramatic -dissolved oxygen can diffuse easier in long, skinny things (large surface area-volume ratio) better than short, fat things (small surface area-volume ratio)
Diversion structures
-Opens up the levee and let water and sediment out -2 diversions thus far -Mixed results -Land is building, but mostly near the diversion -Sediment load not what it used to be -Alters salinity regime - unhappy oystermen
Louisiana Artificial Reef Program
-Operating in all states in GOM -400 obsolete platforms have been converted (300 in La) -Louisiana Artificial Reefs Program began in 1986 -71 oil and gas related companies involved
Subsidence in more detail
-Over time, water logged sediments compact and condense --the sediments compact over time and new sediment is piling on -Natural process called subsidence -New sediment piles on -Parts along the coast no longer getting fresh sediment piled on
Paine's Exclusion experiment
-Paine excluded Pisaster from area near mussel bed -The mussel bed extended down the intertidal by 2 m -Pisaster predation sets the lower distribution of Mytilus -Diversity decreased from 18 to 5 other macroinvertebrates -built an exclusion experiment by building little cages -diversity decreased because the mussels outcompete the other species (competitive exclusion principle) -dominant competitor is the Mytilus (Pisaster eats Mytilus)
Kelps
-Phaeophyta -nereocystis (genus) is the most dominant -form dense kelp forests in rocky subtidal zones -provide structure for many species of nekton, and benthic organisms to live -have gas bladders -Form forests under the water which creates a habitat and food for other species and to hide from predators
Paine's study
-Pisaster ochraceus in lower to mid intertidal preys on barnacles, chitons, snails etc. --Pisaster orchraceus= type of sea star -Pisaster prefers Mytilus californicus --Mytilus californicus= type of mussel -It leaves open space behind where inferior competitors to mussels can colonize
What is the RPD layer and why is it important?
-Redox Potential Discontinuity (RPD layer)= boundary between oxygenated zone and anoxic zone -H2S produced by sulfate-reducing bacteria (use sulfate as oxidizing agent reducing to sulfide) -oxygen poor layers, gray layer above the black anaerobic layer separate aerobic bacteria from fermenting bacteria sulfate reducing bacteria and methanogenic bacteria -at the surface of the sediment, the sediment is pretty well oxygenated -as you move into the reduced black layer, there is a transition called a RPD layer -the amount of oxygen in the water between the sand grains declines with depth -the amount of hydrogen sulfides increases -that is what gives a salt marsh it's rotten egg smell
Sea otters in Alaska
-Sea otters (Enhydra lutris) hunted to near extinction in 1800's by fur traders -Currently re-colonizing islands in southeast Alaska --Some islands have them, some don't and "natural experiments" are possible
Effects of meiofauna on macrofauna
-Settling macrofauna larvae compete with meiofauna -In experiments, increased flatworms and meiofauna reduced recruitment of suspension feeding polychaetes and deposit feeders --recruitment declines so some competition between meiofauna and larval macrofauna
Borers
-Several species of insects and larvae that tunnel into timber -Chemically/mechanically abrade substrate -Molluscs are good borers -rock, wood and ship hulls are damaged by shipworms
Energy flow in a salt marsh
-Spartina has high lignin content --Spartina is really tough -Herbivorous insects graze, but aquatic organisms don't break down detritus --there are some insects that will graze on it --the detritus (dead spartina), when it dies and sinks into the water, not really eaten and broken down -broken down by the Microbial stripping hypothesis --this is the gradual process to get some spartina in the water -Algae much more nutritious food source --Used by more species
Explain Menge and Sutherland's Consumer Stress Model. Draw the basic model and be able to explain the advanced model that includes recruitment and trophic level. In depth. (Picture 11/8 3:52 pm)
-Stress highest at lower intertidal -abiotic stress is most important as you move into high stress environment -At medium environmental stress, competition is most important -At low stress, intertidal predation is most important
Lesson's from Paine's study
-System specific: --Predation inhibits dominant competitor, increasing diversity -General ecology: --Biotic interactions (esp. predation) limits distribution --Predators can suppress dominant competitors --Keystone species concept
Lessons from Connell's studies
-System specific: --Upper limits set by tolerance to heat/desiccation --Lower limit of Chthamalus set by competition -General ecology: --Biotic interactions (esp. competition and predation) limits distribution
Explain other factors that affect kelp forest communities
-Taller kelps can get into a habitat where there is laminaria and you'd think they would shade out laminaria but laminaria grow faster, choking them out -Climax community is laminaria dominating
Temperature tolerance
-Temperatures increase with intertidal height -Cells have higher mortality: less stability --mortality increases with temperature -Upper intertidal more tolerant of high temperatures
Mangroves
-Tropical, intertidal semi-terrestrial plants (shrub to tree size) that tolerate seawater --most dominant in tropical locations -Found in estuaries and behind reefs -Mangal is the habitat -an intertidal community -about 25 genera -provide habitat and structure
Phaeophyta
-Type of seaweed -Eukaryotic protists, multicellular; bottom-dwelling; alternation of generations, present in some primary producers -Dominant component of kelp forests
Cold-water, non-reef building corals
-Very common -Fish nursery -Threat from trawling (fishing with a trawl net) -lots of invertebrates -different from coral reefs
Epifauna
-benthic animals that live on top of rocky substrate
Explain figure 16.4 in the powerpoint (picture in phone 11/8 3:35 pm)
-Wave shock plays big role at low intertidal zone, disturbance form waves important -Desiccation big role at high zone -mid tide competition is most important -Low intertidal predation is becoming important -Distribution on rocky shores of Scotland of adult and newly settled larvae of the barnacles SemiSemibalanus balanoides and Chthamalus stellatus -Width of the bars indicates the relative effects of principal limiting factors -MHW, mean high water -MLW, mean low water -in the upper intertidal zone, tolerance restricts organisms up there -the upper mid intertidal, competition is most important here -below that, predators most importance and the disturbance (wave shock)
Explain the role of predators on the rocky shore. What are the major predators? Prey? How do the predators affect distributions and communities.
-Without Pisaster, mussel distribution extends further down the shore --So predation limits distribution -Limpet grazing of algae very important -Clears algae, but also clears out freshly settled barnacles --As they graze they clear off algae on the rocks --Limpets are a type of mussel that look like little tanks --when there is an open patch of rock, they feed on the algae, as they feed, since built like a tank, tend to crush other larvae on there --so it prevents other larvae from colonizing
Rocky subtidal in Pacific coast U.S.
-Zonation driven largely by depth -Waves weaker in deeper waters --waves weaker in deeper waters than in intertidal waters -Must be shallow enough for light to reach bottom, however --water must be shallow enough for light to penetrate -Giant kelps (Macrocystis) where wave action is weak and water is shallow enough for light -Laminaria, Egregia in shallower inshore waters with stronger wave action --giant kelps do not dominate, laminaria actually dominates
Trawling
-a conservation concern --destroys the habitat -Trawling on hard bottoms (fishing with a trawl net) --Trawls scrape bottom, disturbing or killing benthic animals --Many species are slow growers and slow to recover
heterocyst
-a differentiated cyanobacterial cell that carries out nitrogen fixation
Ephiphytes
-a plant that grows on another plant but is not parasitic
Salt hay
-a slender and wiry plant that grows in thick mats 1 to 2 feet high -type of Spartina -found in salt marshes
Aerenchyma
-a soft plant tissue containing air spaces, found especially in many aquatic plants -allows exchange of gases between the shoot and the root
Mudflat
-a stretch of muddy land left uncovered at low tide
Trophic cascade in rocky subtidal
-a trophic cascade with otters -On islands with otters, kelp is lush and is dominant space holder -On islands without otters, kelp is rare -Sea otters do not eat kelp --So they influence kelp numbers via sea urchins --the otters feed on the urchins, the urchins feed on the kelp, so the otters have a indirect positive effect on the kelp -a 4 level trophic cascade --killer whales ate the otters so otter abundance went down, so kelp sea urchins went up
Mangal
-a tropical community of mangrove plants and associated organisms
What special adaptations do mangroves have to survive in an estuary? (4 adaptations)
-all 25 genera have... 1.) shallow roots with tangled prop roots 2.) aerial root extensions 3.) succulent leaves 4.) Salt glands
Salt glands
-an organ for excreting excess salts -mangroves use these to survive in estuaries
Laminaria
-another type of phaeophyta -dominant algae in some rocky subtidal zones
tophat: the Connell study data suggests... A) Chthamalus can't survive in the lower intertidal B) Balanus is negatively affecting Chthamalus C) Both statements are correct
-answer: B) Balanus is negatively affecting Chthamalus
tophat: To this point, the inequality between subsidence rates and sedimentation rates has been the biggest driver or coastal wetland loss, however, ____ will ____ (increase/decrease) the problem.
-answer: DIVERSION STRUCTURES will DECREASE the problem --the diversion structure (hole) is designed to let more sediment through
tophat: we are losing our wetlands at a rate of 1 football field per______.
-answer: Hour
New England salt marshes
-at high tide, the marsh goes underwater --when they take up water, they take up the salt also, which is bad for the plants -at low tide, it's exposed
Disturbance and Diversity in the Intertidal Zone
-at low levels of disturbance, over half of the boulders only had 2-3 species on it -disturbances in intermediate levels, are frequent enough to remove dominant competitors and allow inferior competitors to colonize --but not so frequent that it inhibits other species from colonizing
How could you design experiments to get at the key question (where the fish on artificial reefs come from)?
-creating an artificial reef in close proximity to a natural reef and monitor population sizes -migration studies -tagging studies -can do caging experiments -can use stable isotopes
Predation on meoifauna
-deposit feeders in sediment, nekton that bite sediment, or suspension feeders on suspended meiofauna -Many juvenile fish with small mouths consume meiofauna -Typically, 90% of meiofauna in fish gut contents are copepods
Problems of oyster reefs
-disease --Infection rate correlates positively with temperature and salinity ---as temps and salinity increase, diseases do better -Dermo --disease caused by Perkinsus marinus: --Important in GOM and Atlantic coast --we have Dermo in LA --Louisiana oysters more resistant to infection -MSX- Haplosporidium nelsoni: --Protozoan --Not found in GOM --do not have MSX here, but a big deal in Chesapeake Bay --Low salinity provides refuge from predators and disease-causing microbes ---there are fewer species of predators and disease in lower salinities
mangroves
-dominant in the tropics
What factors affect RPD depth? How do those factors affect RPD depth?
-donation related to stress and competition -inundation at lower elevations that causes -lower limits of plants set by tolerances -upper elevation limited by competitive ability
Seagrasses
-flowering, submerged plants -about 50 species -eelgrass (Zostera) and turtlegrass (Thalassia) are very common
Algal mats
-forms on the surface of water or rocks -typically composed of blue-green cyanobacteria and sediments -Formation occurs when alternating layers of blue-green bacteria and sediments are deposited or grow in place, creating dark-laminated layers
Balanus
-genus of barnacles
Chthalamus
-genus of barnacles
Pisaster
-genus of huge sea stars
Mytilus
-genus of mussel/bivalve
What might happen if blue crabs went extinct in the GOM?
-get a increase of Littoraria which negativelty affect the spartina
Kelp zonation in Pacific coast U.S.
-giant kelp is a lot taller than laminaria so it gets more sunlight -do not see laminaria growing down low because cannot get that sunlight
Chlorophyta
-green seaweed -Ulva -Codium -Very common, can make the environment more tolerable in rocky intertidal
Oyster Salinity Gradient
-have a lower limit to salinity that they can tolerate -disease pressure increases so have a nice window between 5-15 where Dermo and MSX are not a big deal
Seagrass beds
-hot spots for nekton and infauna -Density and species diversity high in the beds compared to non vegetated sediments -tend to find them in the pacific (tropical and temperate) and in estuaries -tend to be in shallow water because they need sunlight (1-5 m) -form pretty dense beds -only make up 0.1% of the ocean floor
Horizontal or gentle slopes (with light) in Rocky intertidal
-leafy macroalgae (kelp) dominant, although inverts present -sea urchins graze kelp --Note that urchins are important - in the presence of urchins, foliose algae is replaced by calicified (or coralline) algae.
Deposit feeding
-macrofauna -live in tubes for protection -feed outside the tube or move water into tubes for feeding and ventilation -Many infauna mix sediment in a process called bioturbation -messy type of feeding -take mouthfuls of sediment and ingest it --in that mouthful, there is sand that may not have much nutritional value --but also microbes, and other calories in there -may clog suspension feeding apparatus Types: -Tentacles and mucus -Siphons -Break Particulate Organic Matter (POM) into smaller bits -Ex: Fiddler crabs
4 Characteristics of mangals
-mangal= a group of mangroves 1.) depositional, land building environments 2.) distinct animal communities 3.) nursery function 4.) export POM (but crabs may ingest or bury leaves) -POM= particulate organic matter
What caused the decline of oysters in Chesapeake Bay?
-oyster populations <1% of historic populations -Due to: 1.) overharvesting 2.) MSX 3.) Dermo -Previous to 1880, oysters could filter the entire bay in 3.3 days! -Now it takes almost a full year -lot of pollution in the Chesapeake Bay and oysters are a probable cause
Sargassum
-phaeophyta -Sargassum is the genus name -GOM has one of the largest concentration of Sargassum in the world -Recent outbreaks in Caribbean -Habitat for fish, invertebrates
Worm tubes
-pipes or tubes inserted into the soil -commensalism relationship -good for the fish and the crab but not real a benefit for the worm
Experimental design of seagrass beds in Sharkbay, Australia
-put cages around the seagrass beds --Edge habitats - low risk of shark attack --Interior habitats - high risk of shark attack --Exclusions showed sea turtles and dugongs to be significant grazers of the grass RESULTS -Little grazing in interior -Heavy grazing in edge habitat, although varied among grasses CONCLUSION -seagrasses did a lot better in exclusion cages -The presence of tiger sharks in the interior cascaded down the food web leading to increased seagrass (relative to edge) -the tiger sharks reduced the impact of the sea grazers --top-down control
Rate of subsidence vs. rate of sedimentation
-rate of subsidence < than rate of sedimentation = increases land because adding sediment faster than sediment of compacting -rate of subsidence > rate of sedimentation= land sinks faster than new sediment poured on top so land sinks and decreases
Vermiform
-resembling or having the form of a worm -small body with reduced complexity -type of meiofauna
Explain succession on the rocky shore.
-see succession in the rocky intertidal -can go in a variety of direction -the climax community depends on the circumstances -When clear, algae start to grow, the limpets feed and stay with the algae, the limpets are clearing the mussels from being there -If there aren't limpets the next organism that comes in and takes over algae is seaweed -Seaweed can't compete with barnacle so then it comes in and moves seaweeds -If there are no sea stars then the mussels take over
How do mangals show zonation?
-see zonation with salt marshes and also in mangroves -see lots of red mangroves in lower tides -the roots of the mangroves help them hold in in the very loose sediment -the black mangroves (what we have in LA) do not have the root system like the red mangroves, so cannot hold on as easily -black mangroves cannot really grow here -the most stressful ends are in the lower portion (like the salt marshes and opposite from the rocky intertidal zone)
Vertical or steep slope in Rocky intertidal
-sessile inverts (suspension-feeding bryozoans, ascidians, brachiopods, sponges, soft corals and predaceous anemones) -dominant with little leafy macroalgae
mesograzers
-small invertebrate herbivores less than 2.5 cm in length -can include juveniles of some larger species
What is the microbial stripping hypothesis?
-there are lots of particulate organic matter (POM) in deposit feeder guts, but isn't digested very well -Lots of microbes on the POM, much more efficiently digested *Microbial Stripping Hypothesis= microbes are the source of nutrients for deposit feeders -POM decomposed and changed into microbial tissue -Lots of excess plant material = detritus (seagrasses, seaweeds) --when you look into the guts of bottom feeders, see lots of detritus and dead plant material -High C:N content - not easily digested, most animals lack cellulose digesting enzymes --they are not terribly good at digesting plant material -Microbes decrease C:N ratio - more digestible --Waste consumed --the C:N ratio on that particle is declining --also a lot of microbes growing on the plant/detritus; they get digested easily --gets lots of nutrients from the microbes and not the detritus itself -Detritivores consuming microbe heavy detritus which is more nutritious --easier for the deposit feeders to digest --gradually breaks that material down *so microbes play a big role -Cycle that breaks down detritus
Why are cord grass, sea grass, and mangroves foundation species?
-they enhance abundance and species richness of nekton and benthic invertebrates
TMII trophic cascade in seagrass beds in Shark Bay, Australia
-tiger sharks eat dugongs and sea turtles -dugongs eat sea grass -sea turtles eat sea grass -tiger sharks have a direct negative effect on the dugongs and sea turtles -sea turtles and dugongs have a direct neg. effect on the sea grasses -trophic cascade: tiger sharks have an indirect positive effect on the seagrasses (PREDATOR HAS AN INDIRECT POSITIVE EFFECT) -top-down vs. bottom-up control: all about what has the greatest influence on predators -this is top-down control
cordgrass
-type of Spartina -erect, tough, long-leaved plants that range from 0.3 to 3 metres (1 to 10 feet) in height -found in salt marshes
Effect of grazers on kelp diversity
-urchins are big grazers -if you remove the urchins, Laminaria takes over
Menge Model with recruitment added (picture 11/8 4:01 pm)
-will not be asked to draw these figures on the exam -third dimension is the recruitment -less waves move the barnacle larvae -as you move to lower and lower recruitment, less adults, so the importance of competition declines -make sure you understand the 86 model and this model
Ecological roles of seagrasses (7 things)
1.) Dense root mats with intertwined rhizomes stabilize sediment: -sediment in beds differs (muddier) from surrounding non-bed areas -deposition of small particles (sediment and larvae) by baffling inside beds (trap little larvae fish or larvae mollusk) -Increase elevation by 31 mm/yr 2.) Food for large herbivores including birds, turtles, manatees, some fishes: -half of seagrass mass is not consumed by the herbivore -About 50% of seagrass enters detrital food web 3.) Small grazers (shrimp, snails, amphipods) graze epiphytic algae (algae on top of seagrass) 4.) Filter water 5.) Nursery for many commercial fish: -Seagrass beds are hot spots for nekton and infauna --density and species diversity high in the beds compared to non-vegetated sediments -fish grow here until their juvenile stage 6.) Carbon sink : -"carbon sequestration" -11% of organic carbon buried in ocean 7.) One ha seagrass estimated to be worth $19,000/yr
Some common characteristics that salt marshes, mangroves, kelp beds, and seagrass beds share
1.) Detrital food webs -plant material is hard to digest, a lot of animals do not have the cellulose digesting enzyme to break it down 2.) have foundation species that enhance abundance and species richness of nekton and benthic invertebrates 3.) a nursery function -lots of juvenile fish hang out in these habitats -like to hang out where there's structure
Facilitation vs. Competition
1.) Facilitation: -interactions that benefit at least one of the participants and cause harm to neither -either mutualism or commensalism -more likely to occur in physically stressful environments than in favorable environments 2.) Competition: -an interaction between organisms or species in which both the organisms or species are harmed -due to limited supply of a resource
3 reasons to use artificial reefs
1.) Fisheries Production -More habitat = more fish 2.) Restoration/Conservation -Mitigate destroyed habitat, shoreline protection, etc. 3.) Water Quality Enhancement -Adding filter feeders to the water is a good thing
Roles of seaweeds in ecosystems (4 things)
1.) Food -often consumption rates 30% or lower -most ends up as detritus -a theme for seaweeds, seagrasses, marsh grasses, mangroves 2.) Provides structure and habitat: -kelp forests especially 3.) Intertidal seaweeds can facilitate existence of other species by reducing desiccation and buffering temperatures 4.) Can also dominate substrate and outcompete other species
Five factors that cause bands on the rocky shore (zonation)
1.) For sessile species, selection by larvae possible 2.) Homing behavior for mobile species -some limpets territorial -periwinkles will return to a preferred location if swept away 3.) Tolerance -temperature, desiccation, and reduced feeding lead to increasing stress up the intertidal --Temp extremes are greater (winter vs. summer differences). --stress increases as you move up the intertidal zone -Evaporative cooling increases stress -Tolerance to physical stress often sets the upper distributional limit of a species --upper limit where you find a distributional zone is set by what they can tolerate 4.) Wave energy/turbulence -direct (dislodgement) and indirect effects possible -Turbulence increases down intertidal gradient, peaking at mean low water 5.) Predation and competition -Studies by Joe Connell and Robert Paine
Characteristics of rocky subtidal
1.) From intertidal/subtidal boundary to about 200 m 2.) Hard bottoms, bedrock, boulder fields, cobble, and rock walls 3.) Vertical, horizontal or overhanging slopes 4.) Rock stems from geologic uplift 5.) Common but not omnipresent habitat -NOT found in the GOM -North America has been moving west, leaving soft sediments on the eastern side
Production argument
1.) High densities of fish observed at artificial reefs leads to.. 2.) Artificial reefs provide extra nursery, refuge, forage habitat leads to... -there is a lot of fish larvae out there, but there is a limited amount of space for the fish larvae to grow and find food -Wasted larvae that do not have a place to colonize 3.) Artificial reefs are improving stocks, helping conservation -By adding more habitat you give more places for the fish larvae to hide, feed, etc... so by increasing habitat, you increase fish abundance *by increasing habitat, you increase fish stock
Attraction argument
1.) High densities of fish observed at artificial reefs leads to... -have lots of red fish on the natural reef 2.) Artificial reefs merely aggregate fish via behavioral preference; 'steal' from natural leads to... -by creating artificial reefs, taking fish from natural reef and moving to artificial reef -the fish you see in artificial reefs are migrants -the fish prefer to aggregate 3.) Artificial reefs NOT helping conservation but rather, grouping populations for easy fishing -stealing fish to go to an area where they are more likely to get caught by fishing -Stealing individuals from the hard to find reef and bringing them to easier to find reefs -group the fish for more easy fishing around the oil rigs *by increasing habitat, you make the fish more likely to be caught by fishing because easier to find
The 4 major causes of wetland loss in Louisiana
1.) Hurricanes: - marshes weaken hurricanes but get damaged in the process -1 storm can equal 10 yrs of damage -more frequent hurricanes = marsh loss 2.) Canals, Dredging: -cut through the marsh for navigation -Increases erosion -really common -more canals you dig, the more erosion you are going to have -lot of dredging done to get boats through 3.) Invasive species: -Nutria --Myocaster coypus -Invasive rodent from South America -they like to dig burrows in the ground, and the burrows damage the marsh grass roots 4.) Subsidence: -subsidence=the gradual caving in or sinking of an area of land -A river delta is a landform that forms at the mouth of a river, where the river flows into an ocean, sea, estuary, lake, or reservoir. -Young changing systems --rivers do change due to nature --not a stable thing that lasts millions of years --the weight of the sediment on top presses down on the sediment on bottom --squeezing out water out of the sediment
Characteristics of Intertidal soft sediments (Intertidal mud/sand flat) (7 characteristics)
1.) Intertidal mudflats 2.) Sandy bottoms as well 3.) Competition important - but mostly exploitative -more exploitative= less direct interference 4.) Space less limiting, food is more limiting -limiting resource is space on the rock 5.) Suite of predators, no keystone 6.) Predation may be major limiting factor 7.) Likely ample larval supply
Problems that face marshes
1.) Invasive species- Phragmites australis (a broad-leafed grass) -Roseau cane -Invasion in some parts of eastern North America 40,000 years ago -Haplotype M (invasive) becoming much more prominent --We do have haplotype M in LA as well -Dominates marshes upon invasion -Recent invasion of scale insect affecting noninvasive Phragmites
Ecological importance of kelp communities (4 reasons)
1.) Kelp forests monopolize space and act as "foundation" species -Provide food source and protection 2.) Home to grazing food chain and many invertebrates, fish and mammals -Up to 1000 species of plants, fish and inverts 3.) Export detritus to surrounding waters -only 10% of kelp grazed by urchins -like before, plant material is not digested, it ends up as detritus 4.) Evidence for top-down control by sea urchins
What conflicting hypotheses try to explain the decline in seagrass beds?
1.) Light mediated hypothesis 2.) Grazer mediated hypothesis
Types of infauna by size (3 size categories)
1.) Macrofauna: -greater than 0.5 mm diameter (the bigger things) -low density -high biomass /m2 -0.5 - 10 Million species -Bioturbate and influence sediment chemistry -Consumed by bottom-feeding nekton 2.)Meiofauna: -in between 63 µm and 0.5 mm -One 1"core may yield 100 species and 3000 individuals -mostly nematodes and copepods 3.)Microbenthos: -less than 63 µm -Bacteria, fungi, microalgae and protist decomposers -less than 1g /m2 and billions or more/m2 -a lot per square meter -number of species unknown
Grazer mediated hypothesis
1.) Overfishing leads to... 2.) decline of large predators leads to... 3.) increase in small fish predators leads to... 4.) decreased mollusk and crustacean grazers leads to... 5.) increases epiphytes leads to... 6.) gradual loss of seagrass leads to... 7.) decreased recruitment of economically important finfish *top-down hypothesis --remove top predators, add top predators
Why are salt marshes important? (4 reasons)
1.) Protect coasts from erosion and storms -Storm surge attenuated ~8 cm per km of intact wetlands -the waves break up as it goes across the marsh 2.) Support fisheries and migrating birds -lots of migrating birds and fish that hang out in marshy habitats -a lot of Spartina biomass -salt marshes are not very diverse at all 3.) May export energy to surrounding areas -Among the most productive ecosystems in the world -Buffer human impacts especially for nutrient/eutrophication; More and more people live close to coasts (70%) -Rival coral reefs and tropical rain forests in productivity (not diversity) 4.) Remove/store nutrients and sediments
4 Consequences of reduced saltwater marshes
1.) Reduced protection from erosion and storms 2.) Reduced fisheries and migrating birds 3.) Reduced export of energy to surrounding areas 4.) Reduced water filtration
Compare the rocky intertidal to rocky subtidal. How are they similar? Different? With regard to zonation patterns?
1.) Rocky intertidal: -distinct bands of dominant species at various tidal elevation standards -zones are splash and spray, high tide --> mid tide --> low tide -Chlorophyta: green seaweed, photosynthetic, ulva, codium --very common and make rocky intertidal more tolerable -Fucus: type of phaeophyta; dominant seaweed in rocky intertidal, especially pacific coast --very common and abundant brownish band 2.) Rocky subtidal: -important areas where there are a lot of fish and a lot of predators -Kelps -Laminaria- type of brown algae
Differentiate between salt marshes, mangroves, kelps, and seagrasses. What ecological functions do all provide? How do they differ ecologically? In what climate, substrate would you expect to find each?
1.) Salt marshes (vegetated intertidal): -non-tropical -associated with estuaries -flooded intertidal meadows dominated by halophyte grasses -broad, flat expanse of low land with grasses cut by channels leading to larger tidal creeks -mudflats interface with creeks and are exposed to air at low tide 2.) Mangroves: -tropical intertidal semi-terrestrial plants that tolerate seawater -found in estuaries and behind reefs -25 genera that all have: --shallow roots with tangled prop roots --aerial root extensions --succulent leaves --salt glands 3.) Kelps: -Kelp communities well developed near California -Described as a foundation species -monopolize space -provide food source and protection -home to grazing food chain and invertebrates -export detritus to surrounding waters -evidence for top-down control by sea urchins 4.) Seagrasses: -Located at depths 1-5 m -0.1% of the ocean floor are made of seagrasses -stabilize sediment; dense root mats with intertwined rhizomes (sediment in beds are muddier from surrounding areas)( deposition of small particles sediment and larvae by baffling inside beds -increase elevation by 31mm/yrA -used for large herbivores including birds, turtles, manatees, some fishes and about 50% of seagrass enters detrital food web -nursery for many commercial fish -carbon sink -hot spots for density and species diversity high in beds compared to nonvegetated sediments
Types of sediment grains (3 types)
1.) Sand: -largest grain size and less packed together 2.) Silt: -intermediate grain size -more surface area for microbes in silt because there is lots of nooks and crannies 3.) Clay: -smallest grain size and more packed together
Stress adaptations of epifauna to turbulence (4 things)
1.) Short, squat body near surface: -Boundary layer reduces dislodgement -Sea anemones have muscular foot, Barnacles have cement 2. )Rigid body protrudes above boundary layer: -mussels attach by byssal threads and oysters cement themselves to rocks 3.) In crevices or next to neighbors: -reduce shear stress for mussels aggregated in beds -Individuals are stripped from rocks more easily than when in a bed -However when mussels grow on top of each other, they may become unstable and be easily stripped from rocks. 4.) Tall, bendable forms: -help them stay in place when there is high current
Rocky Shore Paradigm. Identify all 5 parts and be ready to apply it to other systems. (essay question before)
1.) Space is a limiting resource 2.) community dominated by superior competitor for space unless: -within this space, there is one species that will drive out and dominate other species and form a monopoly UNLESS 3 conditions: --3.) disturbance or --4.) predation reduces abundance of superior competitor or --5.) tolerance provides refuge for inferior competitors -Works best in the mid-intertidal -This is an organizing principle -explains why the community looks like it does -explains why zonation occurs, what happens if a species can dominate, why it might not -It is a model for other systems -Competition is to out grow other species for space....Simple forms of competitive interactions - by interference... -oriented toward algae -stress includes too much light high in the intertidal
Top-down vs. Bottom-up control
1.) Top-down control= focuses on interactions at top level consumers (predators) and their prey influence on lower trophic forms 2.) Bottom-up control= concentrates attention on how resources (space and nutrients) influence higher trophic forms
Ecological services provided by oyster reefs (4 things)
1.) Wave Breaks 2.) Habitat for Commensal Organisms 3.) Water Filtration 4.) Benthic-Pelagic Coupling
Ecological services provided by oyster reefs (Wave breaks)
1.) Wave breaks: -Intertidal oyster reefs function as a barrier that breaks up wave action -Reduces erosion -Lots of projects to increase oyster habitat -oysters help to break up waves which means that the waves are not as big and as strong, so they do not erode as much of the marsh edge
Light mediated hypothesis
1.) increased nutrient loading leads to.. 2.) increased epiphyte and phytoplankton leads to.. 3.) gradual loss of seagrass leads to... 4.) decomposition of seagrass leads to... 5.) remineralized seagrass nutrients *bottom-up hypothesis --seagrasses are declining due to increased nutrients --add lots of nutrients and fertilizers
Explain the intermediate disturbance hypothesis using Souza's rocky shore experiment as an example. Why is diversity low in 1.) low disturbance? 2.) High disturbance? Why is it high in 3.) intermediate disturbance?
1.) low disturbance: -may be a large boulder because they are heavy and therefore turnover less frequent -low frequencies came from large boulders 2.) high disturbance: -with small boulders that are light in weight and constantly turning over. -High frequencies of disturbances come from small boulders 3.) Intermediate disturbance hypothesis: -where there is not necessarily a high or low frequency of disturbance -where you can find highest species richness -Mid size boulders had the most diversity
Trophic cascades (DMII and TMII)
1.)DMII= density mediated indirect interaction -Often we discuss trophic cascades with regard to affects on density (DMII) 2.) TMII= Trait Mediated Indirect Interaction -predators can also cause trophic cascades by altering traits (often behaviors) of prey -A TMII trophic cascade has been documented in seagrass beds in Shark Bay, Australia
Ecological services provided by oyster reefs (Habitat for commensal organisms)
2.) Habitat for commensal organisms: -all sorts of things hang out on or near oyster reefs -find more fish around an oyster reef, so great for fisheries
Ecological services provided by oyster reefs (Walter filtration)
3.) Water filtration: -help filter out the water column -Reduce eutrophication (excessive nutrients) by filter feeding on plankton -Filter nutrients, phytoplankton, PIM, POM --PIM and POM= particular inorganic matter and particular organic matter
Ecological services provided by oyster reefs (Benthic-pelagic coupling)
4.) Benthic-pelagic coupling: -benthic-pelagic coupling= processes that connect these 2 process (benthic and pelagic) -Filter nutrients, phytoplankton, sediment particles, PIM, POM- keeps 70% for its nutrition -oysters deposit out 30% of what they eat as pseudofeces --pseudofeces= particles that are the wrong size that do not actually pass through the guy of the oysters so are filtered and packaged and expelled out of the oyster as pseudofeces --oysters help filter out the benthic stuff out of the water and package it as pseudofeces --lots of things eat the pseudofeces -Food resource for other benthic organisms
tophat: Which factor is most important in preventing organisms from colonizing the lower intertidal? A)Predation B)Competition C)Stress
A) predation
Tophat: The RPD layer is deeper in .... a.) sand b.) silt c.) clay
Answer: Sand
tophat: Which factor is most important in preventing organisms from colonizing the mid intertidal? A)Predation B)Competition C)Stress
B) Competition
tophat: Given that kelps are in high abundance and have a large impact on the community, they can be described as ____. A.) Keystone species B.) Foundation species
B.) Foundation species -keystone species= have large impact on community, but have small abundance
tophat: Bare rock + algae + barnacles + mussels = A)Diverse community B)Algae and limpets C)Mussel bed
C) Mussel bed
tophat: The importance of _____ will decline as you move up the food web. A)Stress B)Competition C)Predation
C) Predation
tophat: Which factor is most important in preventing organisms from colonizing the upper intertidal? A)Predation B)Competition C)Stress
C) stress
tophat: _____ could lessen the importance of competition. A)Limiting resources B)High density of species C)Limiting space D)Limiting larval supply (low recruitment)
D) Limiting larval supply (low recruitment) -everything else increases competition
tophat: Which of the following is NOT part of the RSP? A.) space is limiting B.) monopolies form C.) unless disturbance suppresses the dominant competitor D.) unless predators suppress the dominant competitor E.) unless there is a tolerance refuge F.) unless competitive networks reduce competition
F.) Unless competitive networks reduce competition
Tophat: Stress ________ as intertidal height _______. A)decreases...increases B)Increases...increases C)Increases...decreases
answer: B) increases... increases
Tophat: The RPD layer will be most shallow in summer or winter?
answer: Summer (because water column is stratified; benthic oxygen is decreased; so oxygen does not pentrate)
tophat: What suppresses diversity at low disturbance?
answer: competition -mussels drive out the other species
Tophat: Which region is the least stressful? •Supratidal •Upper intertidal •Mid intertidal •Lower intertidal
answer: lower intertidal
