[Coral-List] Ulva fasciata

[Klaas Pauly]

Dear David and list,

Ulva fasciata (and other similar species within the genus; identifications
on the specific level within Ulva are often unreliable among authors when
based on morphology/anatomy only) can be regarded as the "nettle of the
sea". It responds very quickly and efficiently to an abundance of nutrients.
These can be provided in a natural way, e.g. through coastal upwelling, as
seen by the abundance (up to 2 or 3 kg/m²) of intertidal Ulva along the
southern, nearly uninhabited and desert-lined coast of Oman), but in other
cases the input of nutrients is anthropogenic, often influenced by naturally
fluctuating conditions (both oceanographical and biological), in a very
complex and hardly predictable way. 
As a consequence, dealing with anthropogenic Ulva blooms implies dealing
with nutrient inputs from estuaries and coastal cities. Building walls to
alter currents might even have an adverse effect, as disturbing sediments
during construction might also stir up precipitated nutrients. 

It might be too late for the main solution in this particular case, but it
often means leaving all naturally occurring habitats as intact as possible.
For instance, seagrass beds are natural and very efficient "nutrient
strippers": they require and absorb a great deal of nutrients from the water
column for their own complex growth and reproduction. Remove these seagrass
beds (often done because they too may cause a bad odour when leaves are
seasonally renewed, and they often harbour sea urchins, a turn-off for
tourists) and the excess of nutrients can trigger an algal bloom. In short,
a difficult task for any local conservation agency, I would say...

Best regards,

Klaas

---
 
Klaas Pauly - Teaching Assistant, PhD Student
Phycology Research Group, Biology Dept., Ghent University
Krijgslaan 281/S8, B-9000 Gent, Belgium
Tel. + 32 9 264 8507
Fax. + 32 9 264 8599
http://www.phycology.ugent.be



-----Original Message-----
From: Medio, David [mailto:MedioD at halcrow.com] 
Sent: maandag 19 mei 2008 16:41
To: coral-list at coral.aoml.noaa.gov
Subject: [Coral-List] Ulva fasciata

Dear Coral list

a coastal tourism development in Peru has an issue with this particular
seaweed growing and/or populating its proposed beaches especially at low
tide. Consequences include bad odour, difficulty with access to the beach
etc.
Similar developments elsewhere I understand have built walls that prevent
(in part) the moving of the seaweed and its infesting beaches set aside for
recreation. This is bound to cause other (hydrodynamic related) problems.
Does anyone have experience in dealing with similar problems.




Dr David Medio
Principal Environmental Scientist
Halcrow Group Ltd, Arndale Centre, Otley Rd, Headingley, Leeds, LS6 2UL, UK
tel: switchboard +44 (0)113 2208220, direct line: +44 (0)113 220 8253,
mobile: +44 (0)773 919 0968
fax: +44 (0)113 274 2924   email: mediod at halcrow.com
www.halcrow.com
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