SUBTIDAL SUBTIDAL ECOSYSTEM ECOSYSTEM

BAT 213

SUBTIDAL ECOSYSTEMSUBTIDAL ECOSYSTEM

Marine areas that are never exposed during low tide ie always submerged

Also known as sublittoral zone

Marine Zonation

SUBTIDAL ABIOTIC FACTORSSUBTIDAL ABIOTIC FACTORS

i) temperature fluctuates from one area to another especially with depth

ii) 1 atm increase in pressure with 10 m depth

iii) strong influence of currents and waves especially those in the shallow depths

iv) turbulence may prevent stratification

SUBTIDAL ABIOTIC FACTORSSUBTIDAL ABIOTIC FACTORS

v) rich in nutrients (brought in from river discharges)

vi) influenced by sedimentation processes (especially shallow areas)

- lithogenic sediments (physical and chemical weathering of rocks)

- biogenic sediments (shells and skeletons of marine organisms)

SUBTIDAL ORGANISMSSUBTIDAL ORGANISMS

Plankton (suspended in water column)

Nekton (able to swim against current)

Benthos (on/in bottom sediment)

SUBTIDAL ORGANISMS

Factors that may influence subtidal organisms:

1. Water depth

2. Distance from land.

Distribution of Marine Life

A. Pelagic

Distribution of marine life

Distribution of Marine Life

A. Pelagic B. Benthos

Distribution of marine life

Distribution of Marine Life

A. Pelagic B. Benthos

1. Demersal

2. Epifauna

3. Infauna

Epifauna

Infauna

SUBTIDAL COMMUNITIESSUBTIDAL COMMUNITIES

A. Soft-bottom Subtidal Communities

B. Hard-bottom Subtidal Communities

SOFT-BOTTOM SUBTIDAL COMMUNITIES

Made up of :

A. Muddy substrate

B. Sandy substrate

SOFT-BOTTOM SUBTIDAL COMMUNITIES

Influenced by:1. Particle size distribution2. Sediment stability3. light4. salinity5. temperature

CHARACTERISTICS OF SOFT-BOTTOM SUBTIDAL COMMUNITIES

Type of dominant substrate ie sand, mud etc.

Most infauna, some epifauna and almost no sessile organisms

SOFT-BOTTOM SUBTIDAL COMMUNITIES

More abundant than soft-bottom intertidal communities

Less abiotic problems :1. No problem with desication2. Temperature and salinity more stable

DISTRIBUTION OF ORGANISMS

Particle size influence distribution of infauna (?)

Particle size distribution (depending on depth)

Easier for organisms to borrow in sand compared to mud (water drainage better in sand)

Patchy sediment type – patchy distribution of organisms

DISTRIBUTION OF ORGANISMS

Some larvae choose substrate before undergoing metamorphosis

Some larvae can detect adults and settle close by

SOFT-BOTTOM SUBTIDAL ORGANISMS

1. infauna Benthic organisms that bury

themselves in the sediment2. epifauna

Organisms that inhabit the surface of the bottom sediment

No. of subtidal sp. > intertidal (more stable, no dessication)Distribution of organisms influenced by particle size (mud or

sand)

PRODUCTIVITY

Minimum productivity(by diatoms and other microalgae)

Most communities based on ditritus

DEPOSIT FEEDERS

1. Polychaetes : accumulation using tentacles or by ingestion of sediment

2. Sand dollars : use mucus to bring food to mouth

3. Bent nosed clam : collect sediment using siphon

4. Brittle stars : collect detritus using tube-feet

5. Peanut worms, sea cucumber, ghost shrimp

Proboscis

Gills

Tube feeding by polycheate, Arenicola Marina. Black arrows show water flow and open arrows show sediment flow. Sediment brought to anoxic area, digested and deposited at upper region of shaft

SUSPENSION/ FILTER FEEDERS Cockles : water intake via siphon Polychaetes and amphipods Brittle star : traps particles using tube feet Sea pens : traps particle from water column

Scavenger dan Predator Shrimps and large crustaceans (scavenger) Whelks dan moon snail : feed on other bivalves Sea stars and crabs (can act as scavenger or

predator) Rays and skates Flounder, halibut and sole

Soft Bottom Communities

Soft Bottom Benthic Communities

HARD-BOTTOM SUBTIDAL COMMUNITIES

Small subtidal communities

Some time they may be in the form of coral reefs

Hard substrate may include organisms that produce calcium carbonate

Rich in epifauna but less as infauna

HARD-BOTTOM SUBTIDAL COMMUNITIES Rocky shore

Coral reefs

Most important organisms are the sea weeds (able to settle on rocks/hard substrate

PRODUCERS

Most important communities - seaweeds

Strong competition

Amount of light influence distribution of sea weeds

Weeds that live in deep ocean. Sea weeds established themselves.

Weeds found in area have higher chlorophyll concentration

grazers Invertebrates that move slowly. : sea urchin,

limpets, chitons, abalone

Algal defence against predators- By having food that are not tasty- Fast regenaration- Calcification (formation of calcium)

Epipelagic

From surface to about 200 m depth (euphotic zone)

Most inhabited depth of the Ocean

Presence of light - photosynthesis

Mesopelagic From about 200 m to 1000 m depth ‘twilight’ or disphotic zone Available light mainly blue Seasonal and diurnal vertical

migration (search for food) Vertical migration can be up to 600 m

Fish (lanternfish – myctophids), zooplankton (particularly crustaceans)

Lantern fish: Myctophidmost abundant fish in deep ocean

Myctophiid: Diaphus holti. About 7 cm long Found at depth 40 – 275 night 225 – 650 day

Bathypelagic From1000 to 3000 m depth Zone of eternal darkness (aphotic

zone) Abundance and diversity of organisms

sharply reduced (mainly due to lack of food)

Abyssopelagic From 3000 m to deepest part of Ocean Zone of eternal darkness (aphotic

zone) Organisms usually colourless Animals normally without eyes but

have ‘flashing’ organs that help them catch food

Angler fish: Cryptopsaras couesi (18 in long)

Anoplogaster cornuta: Commonly calle ‘fangtooth’

Found at around 16,000 feet depth