FACTORS

What are the factors that can affect seagrass growth/ cause seagrass loss?
How does the changing environment impact the seagrass?

Based on notes from Dr Len McKenzie’s Seagrass Workshop last year, here’s a general list of factors that can affect the growth of seagrass!

Factors affecting Seagrass Growth

  • Sediment Quality        
  • Water Depth        
  •  Water Quality  
    • Temperature
    • Salinity
    • Clarity        
  • Nutrients         
  • Current & Hydrodynamic (water movement) processes ·        
  • Interactions with other species (e.g. there must be epiphytes to prevent the seagrass from “sunburn”, but too much epiphytes will suffocate the seagrass.) 

(All this differs for different species types. ) 

*epiphyte: according to “http://en.wikipedia.org/wiki/Epiphyte”, An epiphyte is an organism that grows upon or attached to a living plant.’ In this case, the living plant would be the seagrass.  

Also based on the Seagrass Workshop conducted last year, here’s a list of the factors contributing to seagrass loss

Causes for seagrass loss (due to environment/machinery) to seagrass meadows

  • dredging: removes plants and reduces light availability        
  • grazing (by turtles and dugongs): removes plants       
  • bait & clam digging: physical disturbances of plants, removes plants       
  • anchors & propellers: physical disturbances of plants (cuts up rhizomes, during storms, whole meadows can get uprooted)       
  • flooding: lots of deepwater/freshwater input, sedimentation, herbicide input        
  • increased sedimentation can lead to topography changes such as a raised seabed: overexposure to sunlight      
  • loss of shelter : loss of protection from wind/wave action       
  • Diseases: e.g. labyrinthula – slime mould·        
  • Elevated nutrients: too much epiphytes can smother leaves        
  • Poor catchment practices (diffuse & chronic inputs from modified catchment): sedimentation, herbicides
  • Aquaculture: can result in increased algae blooms, increased sedimentation (block sunlight)       
  • Coastal land development: runoff, acid sulphate soils (sulphuric acid, washed out to seagrass meadow, kills animals), sedimentation       
  • Industrial ports: physical damage (ports often in protected areas, seagrass as well, they have to co-exist), change in topography and water flow, point source discharge (oil spills, sewage and industrial discharge)
  • Shipping: physical damage from grounding, point source discharge        
  • Trawling: physical damage from intensive trawling       
  • Fishing: poisoning, blasting (high in phosphites, algae blooms), set nets (when they drag the nets to catch fish, they uproot sea grass) 
  • Physical damage by ignorant children/ adults

     Finally, here’s a list of the impacts of climate change on seagrass. 

    Impacts of climate change on seagrass        

    • increase in temperature: burnoff, affects distribution and reproduction        
    • sea level rise, increasing water depth so exposure to light is reduced        
    • disturbances through increased number and intensity of hurricanes/cyclones·        
    • elevated flooding frequency and amplitude 
    • slight rise in temperature (1-2 degrees Celcius) even for short period breaks down the enzymes needed for photosynthesis.

       

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s




%d bloggers like this: