Wyprawa badawcza 2015

Catalina Island: from Gobies till to the Great White Shark

When we left Los Angeles by ferry for Catalina early in the morning we could hardly believe that we would find crystal-clear water with fascinating fauna and flora just half an hour away from L.A. Because we planned to continue flying at midnight, we had to calculate our dives very carefully to avoid any avoid health problems during the flight. Divers have to observe a waiting period after diving before they fly again. We calculated a maximum depth of 8 m for max. 30 min and stuck to that 100 %. In return we experienced the cold Pacific from its most beautiful side: clear water with well over 20 °C, plenty of orange-coloured garibaldis (which belong to the family of Pomacentridae). The beauty of the garibaldi is only surpassed by their own young, whose orange is flecked with luminous light-blue. Water measurements indicated a relatively low calcium and magnesium content (360/1084 mg/l). The only corals we found were gorgonians which, like those in the Mediterranean, can tolerate very low water temperatures. One of our reasons for coming here was to observe the incredibly colourful Catalinia goby (Lythrypnus dalli). We didn’t have to search for long. In the rocky habitat of the shallow water they were to be found in large numbers. The small gobies, which grow up to 6 cm in size, are unfortunately only suitable for cold saltwater aquariums, and all attempts to keep them at 25 °C have failed. After completing our investigations and observations we still had some time left to drive to a platform, anchored in a depth of 70 m, where sea lions were sunbathing. As we snorkelled up to them, the animals slid into the water to greet us and then swam elegantly around us. But we kept an eye on the deep blue ocean, because the skipper had told us that great white sharks and hammerheads had often been sighted here. Unfortunately or thankfully no sharks did appear and, after about an hour, we set off on our return journey. For anyone going to visit L.A., we can only warmly recommend a trip to Catalina Island.