Testing DUMO Algacleaner ultrasound technology as a control strategy of freshwater bryozoans in Guadalquivir basin irrigation plants.

1. TESTING ULTRASOUND AS A CONTROL STRATEGY OF FRESHWATER BRYOZOANS
IN GUADALQUIVIR BASIN IRRIGATION PLANTS
Sánchez-Carmona, R.1, Giráldez,J1, Toscano, L.1, Calvo-Júdici R.2 & Toscano, F.1.
1División de Agua y Medioambiente. TOSCANO Línea Electrónica S.L. Autovía A-92, Km 6,5, Alcalá de Guadaíra, 41500 Sevilla. www.toscano.es
2Comunidad de Regantes del Valle Inferior del Guadalquivir. C/Trajano, 2. 41002. Sevilla
E-mail: rsanchez@toscano.es
Freshwater bryozoans are small sessile invertebrates (< 1mm) that grow forming
colonies. In the Guadalquivir Basin have been detected three different species:
Paludicella articulata, Urmatella cf. gracilis and Plumatella sp. (Confederación
Hidrográfica del Guadalquivir, 2014). Results of this work are referred mainly to
Plummatella sp. (Figure 1.A and 1.B).
They grow on hard surfaces, in water pipes of irrigation canals and through the filters
hall at irrigation plant. Their presence affects the normal operation of the plant.
Bryozoans living in pipes may also reduce effective pipe diameter, increasing the
friction and thus slowing water velocities (Figure 2). Definitely, the presence of
biofouling bryozoans increases workloads, reduce efficiency and impedes the delivery of
irrigation water in the Guadalquivir Basin.
Control of the bryozoans proliferation is difficult due to the resistant stage
(statoblast) (Figure 1.C and 1.D), which acts like a seed bank, allowing re-colonisation
when conditions improve (Smith, 2005). Statoblasts enable the recovery of populations
after unfavourable winter conditions. They have the capacity to resist desiccation,
freezing and ingestion by birds (Figuerola et al., 2004).
Control strategies must be directed at reducing settlement and growth of young
colonies. In the absence of any precedent, we are assessing the effect of ultrasound in
the growth of freshwater bryozoans. So, this work arises from de collaboration
between Toscano Línea Electrónica S.L. and the CRVIG to design control strategies
using an ultrasonic treatment. A pilot trial is carrying out in the filters hall of two
irrigation plants of CRVIG to test the effects of the ultrasonic device DUMO
algacleaner, which is manufactured by Toscano Línea Electrónica S.L. (www.toscano.es).
INTRODUCTION
MATERIAL AND METHODS
On 17 March 2014, a weekly monitoring was initiated to describe
growth and development of freshwater bryozoans in two filters
plants of CRVIG (Sector 9 and Sector 7). A device DUMO
algacleaner AC-150 was installed in the Sector 9 to get an ultrasonic
treatment (Figure 3.A,3.B and 3.C) while the Sector 7 was
untreated. Three settling plates were placed at different depths in
each sector. Each settling plate was a 25×25 cm square sheet of
PVC plastic with holes drilled in the corners (Figure 3.D.). Each
stack of plates was tied to the bars and suspended in the water.
The top plate was immersed about 70 cm, the middle one about 140
cm and the bottom one about 210 cm below the water surface.
Settling plates were photographed and observed weekly. Percentage
of statoblasts germination and changes in the growth were
described in treated and untreated plates. In each sampling we
taken data of temperature, pH, conductivity and turbidity.
RESULTS AND DISCUSSION
More than 11 visits had been made so far. No
significant differences were found between water
parameters in treated and untreated filters
plants (Kruskall-wallis test results: Temperature:
F= 0,008, p=0,931, pH: F=0,404, p= 0,525,
Conductivity: F= 0,101, p= 0,751 and Turbidity: F=
2,431, p= 0,119 ) (Figure 4).
REFERENCES
* Confederación Hidrográfica del Guadalquivir, 2014. Manual de las buenas prácticas en instalaciones afectadas por briozoos.
* Figuerola, J., Green A.J., Black, K. And Okamura B. 2004. Influence of gut morphology on passive transport of freshwater bryozoans by waterfowl in Doñana (southwestern
Spain)
* Smith, A.M., 2005. Growth and development of biofouling freshwater bryozoans, Southern Reservoir, Dunedin, New Zealand, November 2000 to June 2004. Denesia 16,
zugleich Kataloge der OÖ. Landesmuseen Neue Serie 28: 209-222.
* Wood, T., 2005. the pipeline menace of freshwater bryozoans. Denesia 16, zugleich Kataloge der OÖ. Landesmuseen Neue Serie 28 : 203-208.
1) Information about growth pattern of freshwater bryozoans in Guadalqivir Basin is scarce.
2) Ultrasound reduces germination percentage of statoblasts.
3) Ultrasound could to affect the development of maduration of Plumatella sp colonies.
4) Ultrasound could significantly affect the statoblasts production. Studies about the viability of statoblasts produced under ultrasonic treatment are
needed. They could provide us information to design a control strategy of massive growth of freshwater bryozoans.
5) Ultrasonic treatment of water in irrigation plants shows some potential for significantly lessening settlement and growth of freshwater bryozoans and
mainly cause damages in the statoblasts production.
6) Full scale trial are needed to assess the viability of ultrasonic treatment to resolve the great problems that freshwater bryozoans are causing in
irrigation plants.
CONCLUSIONS
Figure 1. A) Freshwater
bryozoan belonging to
genus Plumatella sp. B)
Plumatella sp under
binocular microscope. C)
Plumatella sp producing
statoblast. D) Statoblast:
resistant stage of
Plumatella sp.
A C
D
B
Figure 2. Damages caused by freshwater bryozoans in the irrigation plants of CRVIG
(Comunidad de Regantes del Valle Inferior del Guadalquivir).
Figure 3. Installation of DUMO algacleaner in Sector 9 of CRVIG (A, B, C).
Settling plates used in the sampling (D).
A
B
C
D
We observed how Plumatella sp colonies had also
grown in treated plates (Figure 5). They mainly
have covered the undersides of the
plates. Bryozoans are among the invertebrate
animals that thrive in dark places where
continuously flowing water brings an unlimited
supply of particulate food (Wood, 2005).
It is observed that a lot of mud is accumulated
forming a great and consistent stratum when
colonies grow This probably difficult the
infiltration of any chemical product to remove
them. Moreover, probably this also form a
favorable environment to the settlement of other
invasive species like as Corbicula fluminea.
Figure 4. Data of temperature, pH, conductivity and turbidity in
both sampled filters hall water (Sector 9:treated and Sector7:
untreated).
Figure 6. EFFECTS ON STATOBLASTS GERMINATION. Treated
plates (left) showed lower germination percentages than untreated (right).
However, we have found three highlight in the preliminary results. They could help us to design effective and
possible strategies to mitigate the massive growth of these invertebrates using the ultrasound:
1) Effects on statoblasts germination (Figure 6).
Figure 5. Plumatella sp. colonies growing in the undersides of treated plates.
2) Effects on mature colonies formation (Figure 7).
Colonies began to mature from early June. Treated and untreated colonies show some differences: different colour,
zooids density and zooids length. Untreated colonies were softer than the treated. Ultrasound would disrupt the
capacity of the colony to form some of their body parts.
3) Effects on statoblasts production (Figure 8).
Untreated colonies are starting to produce statoblasts, resistant structures which are the “seeds” to start a new colony
growth when conditions are favorable . However, colonies under stress caused by ultrasound are producing significantly
lower amounts.
Another issue is to assess if statoblasts produced under ultrasonic treatment are viable and competent to hatch later on.
We are currently designing laboratory experiments to observe the viability of these statoblasts.
Any method that remove freshwater bryozoans colonies provides a temporary solution, because it is not prevent new
colonies forming the next summer. The long-term solution lies in controlling germination or production of reproductive
units of the invading species, i.e. statoblasts. Further researches in this issue are required to deal the problem of
massive proliferation of freshwater bryozoans.
FULL SCALE TRIAL
Full scale trial are ongoing in other affected sector of CRVIG (Sector 6) since 7th April. We are using an ultrasonic device
with a power ten times greater than the used in the pilot test in filterers hall. We will know the results at the end of the
summer season.
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Temperature (ºC)
Sector 9 (TREATED) Sector 7 (UNTREATED)
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pH
Sector 9 (TREATED) Sector 7 (UNTREATED)
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Conductivity (µS/cm)
Sector 9 (TREATED) Sector 7 (UNTREATED)
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Turbidity (NTU)
Sector 9 (TREATED) Sector 7 (UNTREATED)
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26_MARCH_14 2_APRIL_14 9_APRIL_14 23_APRIL_14
Sector 9 (TREATED) Sector 7 (UNTREATED)
Percentage of statoblasts germination were significantly
lower in treated plates than in untreated ones (Mann-
Whitney test: F= 0,000, p< 0,005). After nine days of
ultrasonic treatment only 9,24% of statoblasts germinated
in treated plates while 94,29% of statoblast germinated
in untreated plates.
Percentages of germination closed to 100% remained in the
next samplings in untreated plates while this percentage
remained under 10% in treated plates. Tiny colonies began
to grow from 6 May. (Figure 6.1)
Figure 6.1. Percentages germination of statoblast
in treated and untreated plates .
TREATED
UNTREATEDTREATED
UNTREATEDTREATED
Figure 7. EFFECTS ON MATURE COLONIES FORMATION.
Colonies that grow under ultrasonic treatment (left) show different features than
colonies untreated (right).
Figure 8. EFFECTS ON STATOBLASTS PRODUCTION. Plumatella sp
colonies under binocular microscope. Untreated colonies (right) are producing a
greater amounts of statoblasts than treated colonies (left) significantly.
Ultrasound could reduces statoblast production.
UNTREATED