JBL Workshop 2007 Philippines

Research tasks and results

Water analysis – marine: water samples were taken at the surface above the reef at depths of 5, 10, 20 and 30 meters and evaluated immediately on our return to the resort. JBL water tests and a WTW 340i multi-test instrument were used for the analyses. For water tests taken underwater, the following procedure has proven the best: fill the sample bottle with surface water. The bottle is opened at the corresponding depth and inverted. Divers then fill their bottle with air from their reserve cylinder (Octopus). The air forces the water out of the bottle, so that the bottle can now be turned the right way up and water from the corresponding depth flows in. As an alternative, fish transport bags have proven to be very useful. They scarcely take up any room when folded up and can be filled by simply moving them backwards and forwards through the water. All containers have to be labelled before the dive, to ensure correct identification later.

Results

Results found Depth 0m 3 m 10 m 20 m 30 m
Date Jun 07        
Time 10:00 a.m. 10:10 a.m. 10:15 a.m. 10:20 a.m. 10:30 a.m.
Temperature in °C 29 29 26 25 24
Salt content in per mille 1.023 1.023 1.022 1.022 1.022
CH 7 7 7 7 7
pH (electr./JBL) 8.35/8.2 8.29/8.2 8.30/8.2 8.25/8.2 8.22/8.2
Calcium in mg/l 400 400 400 410 420
Magnesium in mg/l 1500 1500 1500 1700 1800
Nitrate in mg/l 0 0 0 0 0
Phosphate in mg/l 0 0 0 0 0
Conductivity in mS/cm 49.3 49.2 49.5 49.6 49.7
Oxygen in mg/l (electr./JBL) 5.0/5.0 5.2/6.0 5.2/5.0 5.0/5.0 5.0/4.5

Zoning trials

Each group noted all the sessile (stationary) animals along an imaginary line from the shore to the floor of the reef. Such zoning gives a section through the reef and the immediate biotope. It provides information on the animals to be found and can be compared with other zoning. Zoning has already been carried out in the first JBL Workshop at the Red Sea and on the Maldives.

Artificial reef

The participants constructed two artificial reefs made of aerated concrete underwater. The first reef was at a “snorkelling depth” of only 3 m approx. The second reef was built by the divers at a depth of 10.8 m on a sand bed five meters from the natural reef. Immediately after construction, colonisation by fish and their behaviour was studied. Colonisation of the snorkelers´ reef could also be compared with that of the divers´ reef. The project was headed by Prof. Dr. Ellen Thaler who personally observed the snorkellers´ reef.

Observations

Both artificial reefs were constructed on 23.06.07. Construction of the snorkel reef at a depth of 3 m was completed at 11:15 Uhr and by 12:00 the first inhabitants had appeared.

  • Abudefduf sp. 2 – 3 individuals
  • Various sweetlips swim in and out. Thalassoma lunare adult and juvenile, 3 – 5 individuals. Thalassoma sp. and halichoeres hortulanus juv, 1 individual.
  • Cautious approach by a sapphire reef cichlid (chrysiptera cyanea).
  • Juvenile sweetlips (plectorhynchus lineatus) moves in at the bottom.
  • 1 pomacentrus sp (black/grey) can be observed

24./25.06.07

  • 09:00: pomacentrus lives down below and cleans other fish!
  • Abudefduf number has risen to 8 individuals
  • 1 apogon has joined them.
  • Other colonisation as on previous day

25.06.07

  • 10:30: 3 dascyllus trimaculatus spawning on the top rock. All other fish chased away (11:00)
  • 15:30: Even the young sweetlips avoid the area.
  • 20:00 with UV lamp: sweetlips , apogon and abudefduf are allowed to return to the rocks at night!

26.06.07

No change on the previous day. Male dascyllus guarding the spawn. All other fish keeping their distance.

27.06.07

  • Male dascyllus still guarding the spawn.
  • In the middle of the reef were 2-3 abudefduf, which were constantly chased away, but returned time and again.
  • The apogon gave up and moved out .
  • Thalassoma going in and out (4-6 individuals).
  • 2-3 saphire cichlid have set up home below.
  • A second painted sweetlips has moved in with the first one at the bottom.
  • The blacj/grey pomacentrus has disappeared.

Observations on the divers´ reef

  • Initial colonisation about 3 hours after the construction of the reef.
  • As on the snorkel reef, the first inhabitant was a dascyllus .
  • In the next few hour of the day it was joined by a painted sweetlips and a few abudefduf.
  • At night, too, no further inhabitants could be discovered.
  • After three days colonisation had not changed.

Observations on the artificial tyre reef

  • This reef was built 7 years ago. Several tyres were linked together and lowered about 18 m onto a sand bed. In the meantime the tyres have become so densely colonised by invertebrates that only the shape of the tyre can be discerned. Fish density in the area of the tyres was significantly higher than on the reef slopes nearby. The tyres provided larger caves and shelters than the reef slopes and therefore there were more large fish there. Only small invertebrates, such as slugs and crustaceans were more common in the naturally formed reef.
  • It remains to be seen whether our artificial reef of stone is colonised just as well/faster as the old tyres by invertebrates. The rough surface of the stones ought to favour colonisation by invertebrates better than the smooth rubber surface. We will receive a brief interim report from the dive instructors in Atlantis every year.

Underwater feeding trials

All particpants took a food can (JBL MariPerls) with them when snorkelling or diving. They observed which fish ate JBL MariPerls and which did not. The results were immediately noted on writing pads underwater. Special features of unidentified fish were noted and then identified with the help of literature and expert guidance.
Results table as download (PDF -48KB)

UV measurements

Using a UV measuring instrument (PCE-UV 34) the total UV radiation was measured at different locations on land. The instrument measures both UV-A and UV-B. Using a photo filter (Hama UV-A 390), the UV-A rays could be eliminated and only the remaining UV-B rays measured. The objective was to quantify UV radiation at the Equator, to give terrarium enthusiasts precise information on the conditions their animals when kept species-appropriately.

UV-A and UV-B together: 0.83 – 0.84 mW (light cloud)
UV-A and UV-B in the shade together: 0.036 mW
UV-A eliminated by filter, remaining UV-B proportion: 0.025 mW (= 69 %)
Resulting UV-A proportion: 0.036 – 0.025 = 0.011 mW (= 31 %)
UV-A and UV-B together in rainforest: 0.104 mW
With UV-A filter at front. Resulting UV-B level: 0.060 mW (= 58 %)
Resulting UV-A proportion: 0.044 mW (= 42 %)

In Germany (Neuhofen/Pfalz) total UV level measured with cloudy sky:
1.26 mW.
Measured with UV-A filter: 0.48 mW (= UV-B. Corresponds to 38 %)
Resultiny UV-A level: 0.78 mW (= 62 %).

Rainforest / freshwater

Two trips visited the rainforest on Negros Island. Water analyses were carried out on small rivers and lakes, fish were caught and the temperature and humidity were measured.

Freshwater results

Date 25 June, 2007
Time 11:45
Temperature in °C 25 °C
TH 4
KH 2
pH (electr./JBL) 7.5
Nitrate in mg/l 0
Phosphate in mg/l 0

Results for waterfall

Date 26 June 2007
Time 10:50
Temperature in °C In the waterfall: 24.5;
Quiet zone behind: 25.5 °C
GH in ° dGH 3
KH in ° dKH 0
pH (electr./JBL) 5,5/< 6,0
Nitrate in mg/l 0
Phosphate in mg/l 0
Conductivity in µS/cm 162
Humidity in % (relat. humidity) 74
Air temperature in °C 31

Underwater behavioural studies of cleaning stations

  • Labroides dimidiatus (bluestreak cleanerfish): a „cleaning session“ took on average five minutes.
  • We were unable to observe that the host fish gave any sign to the cleaner fish to indicate that it wanted cleaning to finish. It simply swam away.
  • The fish did not look for cleaning fish, but rather deliberately visited the cleaning stations which they seemed to know.
  • If the cleaning station happens to be occupied, they swim further or wait in the vicinity until a cleaning fish is free.

Visiting the Silliman University in Dumaguete

Silliman University was founded by the Americans in 1901 abd is the oldest US university in Asia. The university is named after Dr. Horace Brinsmade Silliman who donated the funds for the Presbyterian Church.

About 500 staff look after 6000 enrolled students. The JBL team visited the marine biology area of the university and were shown the current projects as well as the research facilities. On the tour Bernd Schmölzing spotted the German flag: but it was hanging upside-down. To the dismay of the staff, he immediately took it off the wall and corrected the error.

Although the Marine Biology Faculty is the leading one in the Philippines, the JBL team was very disappointed. Coral communities were kept in large concrete ponds which look more like neglected ponds. For behavioural studies, anemone fish languished in mini aquariums.

But the first signs of ecological thinking are very important in this country. Marine life will no longer be seen as an endless source of food, but rather as part of nature, which has to be cherished, looked after and above all valued. Amongst the younger generation, this change of attitude has in part already taken place.