Week 9- Coastal Eutrophication and Case Studies

Define oligotrophic

Low nutrient status aquatic environment

e.g. gyres

Define eutrophic

Nutrient rich region

e.g. coastal regions

Define mesotrophic

Intermediate

e.g. most coastal shelf

Define hypernutrification

Excess nutrients in estauries

Define eutrophication

Enrichment of environment with nutrients and associated priduction of undesirable effescts

What is undesirable disturbance

Pertubation of marine ecosystem degrading health/threatens sustainable use of it

How does eutophication occur

1. Increased plant nutrient conc predominantly nitrate and phosphate

2. Increase nutrient conc and increase plant production

3. = Changes species composition e.g. some have advantage

   abnormal algal blooms

   toxic algal bloom

   deoxygenation (system swamped with phytoplankton)

   adverse affects on fish/invertebrates

   changes structure of benthic communities

Define nutrient pollution

Excess nitrogen and phosphrous in aquatic systems

• One of the leading causes of poor water quality

Where are the natural levels of nutrients in sea from

1. Rivers

2. Air (atmospheric dust)

3. Natural excretion/fixation

4. Oceanic mixing

Human activities add to natural processes causing nutrients in sea what are the anthropogenic things that change nutrient level

1. Sewage

2. Fertiliser run off

3. Livestock waste

4. Industrial effluence

Stages of eutrophication

1. Excess nutrients= decreased oxygen

2. Excess algal growth= harmful algal blooms

3. Reduced sunlight

4. Algal death

5. Bacteria digest dead plants= use remaining oxygen= give off carbon dioxide

6. If they cant swim away fish/other wildlife become unhealthy/die without oxygen (particularly bad for shellfish)

What has become one of the biggest problems overall

Sewage - water companies only just beginning to get penalised

Used to be sludge boats

Define sewage

A mixture of all liquid domestic waters

include human body waste, fecal, urine, household, chemical/indistrail wasteb

What type of pollutant is sewage

oxygen demanding

How do you measure biochemical oxygen demand

Take water bottle and put in dark and then see how much bacteria grows

What is the different measurements of biochemical oxygen demands in a river

<2mg/l - unpolluted

>10mg/l grossly

Urban sewage has around 500mg/l

Ways to treat sewage

Preliminary treatment, primary treatment, secondary treatment, tertiary treatment

What is preliminary treatment

Screening large objects, maceration/grit removal.

Removes wood paper and bottles

What is primary treatment

Suspended soils separated out as sludge

What is secondary treatment

Dissolved/colloidal organics are oxidised in micro-organisms presence

What is tertiary treatment

High quality effluent required

May involve removal of further BOD, bacteria, suspended solid toxic compounds and nutrients

When do dry spills occur

Can take place when lots of rain

lIlegal dry spill- untreated wastewater spills straight out of river into seas when no rain

How does normal operation sewage discharge flow

Wastewater flows smoothly through system to sewage treatment plant

Desribe a legal sewage spill

Water companies can spill untreated wastewater at times of heavyprolonged rainfall

How is sewage discharge recorded

Water level sensors detect release at designated points (start and end of overdlow)

Allows untreated sewage into environment

Sensors measure start of overflow at end which gives us a duration

Only 80% is measured

Any discharge in first 12 is 1 spill

Any additional spill in 24 hours is 1 additional spill block

What is a balanced marine ecosystem defined by

1. An pelagic food chain that effectively couples production to consumption and minimises potential for excess decomposition

2. Natural species composition of plankton and benthic organisms

3. Natural distribution of submerged aquatic vegetation

What can eutrophication cause

Dead zones- hypoxia (decreased oxygen in water)

Where is really hypsoix water

Baltic as inland sea

How will oxygen minimum zones increase

Intermediate deots within ocean

Oxygen decrease in 300-700m layer is 0.09 to 0.34 micro mole/kg per year

What does remineralisation do

Decreases ixygen

Describe dead zone in Oregon coast

Upwelling in Summer brings large source of nutrients/iron

Fuels phyto blooms= large amount of krill

Upwelling stops an phytoplankton die and sink and decomposition = low oxygen

Crabs/bottom fish cab’t die/move out of hypoxic zone

Describe another dead zone

Gulf of Mexico

• Excess nutrients from cities/farm in upland watersheds drain into Gulf and stimulate phyto growth in spring and summer

What have hypoxic water found to do

Effect fish diets/growth/reproduction/habitat

Is Southampton water eutrophic

Can be

• Measured using automated data buoy (do get variability tho)

What does southampton water data buoy measure

temp, salinity, dissolved oxygen, oxygen saturation, chlorophyll, turbidity

What water blooms were found in southampton in 2019

3 different species - globosa, delicatula, rubru,

What can you see from algal blooms

Surface organic blooms

What leads to red tide

Mesodinium rubrus- harmful red tides

Is fleet lagoon eutrophic

Yes, very commonly

As not getting mixed often has a barrier

Huge algal blooms/mats

What sort of signs do you see near fleet lagoon

Toxic shellfish

What is lough neagh in n.ireland like

Largest freshwater crucial for drinking water

Good for looking at laws etc

site of special scientific interest

Clearly see blue/green algae

Where do cyanobacteria thrive

Anywhere, often oligotrophicm can from harmful algal blooms in warm nutrient rich areas, health risk, disrupt aquatic ecosystem, skin irritation to neurological damage

What is the cause at Loch neagh

Large rise in nutrient pollution from land-agricultural run off

Swage discharge increase

Large nitrate and phosphate increase

What % of storm overflows in N.Ireland drain into rivers that flow into lough neah

28%

What are the ecological consequences of storm overlows at lough neah

80% decrease in migratory birds

66% decrease in insect/small species

Large decrease in fish species

Very large toxic blooms

How do you get from a worseing situation to improving

Water friendly agricultural practice

Urban runoff and sewage management

Wetland restoration

Community engagement

Real time monitoring

What are water friendly agricultural practices

Work wtih farmers

Install livestock fencinf

Soil testing

Tree planting

Buffer zones

How to improve water quality of sewage treatments

Enhance stom water management and sewage treatment

Soft engineering solutions with sustainable urban drainage systems

Reed beds/wetlands installed

What is another big way in improving practice

Community engagement / people power

How is real time monitoring important

Implement real time and open access data

Enable swift response to pollution incidents

Protects ecosystems and public health