The Shallow OceanThe Shallow Ocean

Factors and processes in the shallow oceanFactors and processes in the shallow ocean

Habitats:Habitats:estuariesestuariestidal flatstidal flatslittoral zone littoral zone continental shelfcontinental shelf

Benthic effectBenthic effect““Benthic Effect”Benthic Effect”

Ocean: Ocean: independent of ocean floor; vertical zonesindependent of ocean floor; vertical zonesCoastal zone: Sediment, water column coupledCoastal zone: Sediment, water column coupled

Water Water oxygenated: algaeoxygenated: algae, microbial loop, microbial loopTop sed oxygenated: algae, microbial loopTop sed oxygenated: algae, microbial loopBeneath: dysoxic to anoxicBeneath: dysoxic to anoxic

Environmental Environmental VariabilityVariability

Daily variability: T, salinity, tides, wind strength etc.Daily variability: T, salinity, tides, wind strength etc.

Annual variability: Seasonality, stormsAnnual variability: Seasonality, stormsSediment input, freshwaterSediment input, freshwater

10’s – 1000’s yrs: Sea level change, climate change10’s – 1000’s yrs: Sea level change, climate changeMY’sMY’s: : Plate tectonics, conveyer circulationPlate tectonics, conveyer circulation

Nutrients, oxygen, carbon dioxide: daily through MY’sNutrients, oxygen, carbon dioxide: daily through MY’s

EstuariesEstuariesEstuary: where freshwater (i.e., river) meets the oceanEstuary: where freshwater (i.e., river) meets the ocean

Requirements to be an estuary:Requirements to be an estuary:1. FW input1. FW input2. Open connection to ocean2. Open connection to ocean3. Area of FW/SW interaction3. Area of FW/SW interaction

3 zones: 3 zones: Tidal river zone; mixing zone; nearshore turbid zoneTidal river zone; mixing zone; nearshore turbid zone

Estuaries: EcologyEstuaries: EcologyVery productive and very sensitive habitatVery productive and very sensitive habitat

High biomass: plants, microbesHigh biomass: plants, microbesLarge nutrient, sediment fluxLarge nutrient, sediment fluxFish nurseriesFish nurseriesDepth, salinity, T vary w/ seasonality, tides, FW QinDepth, salinity, T vary w/ seasonality, tides, FW Qin

Can have FW top, SW benthosCan have FW top, SW benthosSeasonal variationsSeasonal variationsPollutant filterPollutant filter

Example: Laguna MadreExample: Laguna Madre

Shallow: most <1m deep with Shallow: most <1m deep with

0.5m tidal range0.5m tidal rangeTides 2X dayTides 2X day

Inlets on each end of barrier Inlets on each end of barrier islandisland

Reversed salt wedgeReversed salt wedge

Hypersaline, high evaporationHypersaline, high evaporationTX weather: varies TX weather: varies

between between arid and monsoonal arid and monsoonal stormsstorms

Example: Laguna MadreExample: Laguna MadreSea grass behind barrier Sea grass behind barrier islandisland

Invertebrates: oysters, Invertebrates: oysters, clams, polychaetes, crabs; clams, polychaetes, crabs; fish fish

Sand and euryhaline Sand and euryhaline succulents on barrier islandsucculents on barrier island

Sea birds, feral cats, Sea birds, feral cats, rattlesnakes, rodents, rattlesnakes, rodents, insectsinsects

Barrier island stabilized, not Barrier island stabilized, not allowed to migrateallowed to migrate

Drowned river valley since LGMDrowned river valley since LGM

Major fishery: oysters, crabs, fishMajor fishery: oysters, crabs, fish

Oysters where FW, SW meet and Oysters where FW, SW meet and mixmix

1900: enough oysters to recycle 1900: enough oysters to recycle H2O in 3 daysH2O in 3 daysnow: 1.5 yearsnow: 1.5 years

Example: Chesapeake Example: Chesapeake BayBay

Example: Chesapeake Example: Chesapeake BayBay

Seasonal stratification, anoxiaSeasonal stratification, anoxia

Spring: a lot of FW: strong pycno- and Spring: a lot of FW: strong pycno- and haloclinehalocline

Stratification: anoxia on bottomStratification: anoxia on bottom

Seasonal variations in biomass, Seasonal variations in biomass, communitiescommunities

MangrovesMangrovesTropical estuaryTropical estuaryTrees instead of marshTrees instead of marshImportant nursery habitat, local fisheryImportant nursery habitat, local fisheryClear cut for development, aquacultureClear cut for development, aquaculture

Littoral ZoneLittoral ZoneWithin tidal rangeWithin tidal rangeEffected by beach processes, sedimentsEffected by beach processes, sediments

Rocky or sandyRocky or sandyHigh energy environmentHigh energy environmentOrganisms:Organisms:

Infauna common: polychaetes, molluscsInfauna common: polychaetes, molluscsMussels, limpets, chitons, arthropodsMussels, limpets, chitons, arthropods

Communities:Communities:Algae gardens, sea grass beds, Algae gardens, sea grass beds, infauna patches, hard surfacesinfauna patches, hard surfaces

Example: Bathtub RockExample: Bathtub RockLa Jolla, CALa Jolla, CA

West coast: erosional: hard surfacesWest coast: erosional: hard surfacesUneven sour --> pools of water, rough sidesUneven sour --> pools of water, rough sides““Bathtub” on topBathtub” on top

Biotic zonesBiotic zones

Low tide: Low tide: rock is exposedrock is exposedMussels closed tightMussels closed tightVagile organisms stillVagile organisms stillCrabs at workCrabs at workExposure to predatorsExposure to predators

High tide: rock sides under water, but high EHigh tide: rock sides under water, but high EOrganisms feed, vagile critters move and feedOrganisms feed, vagile critters move and feed

Shallow ShelfShallow ShelfMany invertebrates, vertebrate organismsMany invertebrates, vertebrate organismsAlgae if shallow enoughAlgae if shallow enough

Floating algae: Floating algae: SargasmSargasmAttached algae: KelpAttached algae: Kelp

Complex food webs:Complex food webs:types producers + sessile benthos + vagile predatorstypes producers + sessile benthos + vagile predators

Storm eventsStorm events --> stable environment with occasional perturbations--> stable environment with occasional perturbations

Shallow shelf: active marginShallow shelf: active marginUpwelling in spring, summerUpwelling in spring, summer

Cold water, oxygen, nutrientsCold water, oxygen, nutrientsPlankton bloom --> albacore, Plankton bloom --> albacore,

others --> sharksothers --> sharksKelp forestsKelp forests

Sea urchins, lobsters, diverse Sea urchins, lobsters, diverse attachers, benthic invertsattachers, benthic inverts

fish, seals, sea otters, killer fish, seals, sea otters, killer whaleswhales

Fairly stable environment, complex Fairly stable environment, complex food websfood webs

Example: Offshore CAExample: Offshore CA