Um es vorweg zunehmen, auch dem Aquarium ist es nicht gelungen die Muricella zu der Zeit am Leben zu erhalten. Ob sie es noch mal versucht haben, entzieht sich meiner Kenntniss.
Dieser Text ist in Englisch.
PRELIMINARY NOTES ON THE HUSBANDRY
OF THE PYGMY SEAHORSE, Hippocampus bargibanti WHITELEY, 1970
AND ITS CORAL “HOST”, Muricella plectana, VERRILL, 1869
AT THE WAIKIKI AQUARIUM, HONOLULU, HAWAII, USA
Norton Chan and J. Charles Delbeek
Waikiki Aquarium, Honolulu, HI, USA
The pygmy seahorse, Hippocampus bargibanti Whitely, 1970, is considered one of the smallest marine vertebrates in the world at a maximum size of about 1.5-2.0 cm. Given its diminutive size and striking appearance, they have long been sought after for display by public aquariums around the world. They were first discovered in 1969 by Georges Bargibant of the Noumea Aquarium in New Caledonia clinging to a newly collected gorgonian (Lourie and Randall, 2003). These seahorses are further unique in that they are only found living in close association with two species of gorgonian, Muricella plectana (pale grey or purple with pink or red tubercules) and Muricella paraplectana (yellow with orange tubercules) and perhaps Anthogorgia to which it is closely related (Fabricius and Alderslade, 2001; Lourie and Randall, 2003).
Photo 1. Pygmy seahorse, Hippocampus bargibanti, in situ on the gorgonian
Muricella plectana, Lembeh Strait, Sulawesi, Indonesia. J.C. Delbeek
Muricella spp. are commonly found growing along reef slopes and drop-offs, where they encounter strong tidal currents and high particulate loads. The are found at depths exceeding 20 m (~65 ft) (Kuiter, 2001) throughout the Indo-Pacific region and southern Japan, but are not common. In areas where cooler waters come closer to the surface, it can be found somewhat shallower e.g. Lembeh Strait, Sulawesi, Indonesia (C. Delbeek, pers. obs. 1997; Kuiter, 2001). As a result, the optimum temperatures for these corals mostly likely lie between 25 oC (78 oF) and 18 oC (65 oF), depending on geographic location and depth. Large and fan-like in appearance they can be brown, yellow, pink, orange or white with the polyp colour often strongly contrasting that of the coenenchyme (Fabricius and Alderslade, 2001).
The key to keeping H. bargibanti is the husbandry and survival of its host; Muricella. Unless one can keep Muricella alive, the chances of successfully keeping H. bargibanti is probably close to zero. The reason for this is that H. bargibanti relies on the polyps of Muricella to trap food items that it then plucks from the tentacles of the coral. This behaviour led to claims that the seahorse actually consumed the coral polyps (Kuiter, 2001) and to the unaided eye, observing underwater through a SCUBA mask, it may certainly appear to do so, but from our observations this was not the case. This differs from the newly described species Hippocampus denise, which is distinguished from H. bargibanti by being smaller, more elongate with fewer bumps and being found mostly on pink or orange Melithea spp. sea fans, Annella, Echinogorgia as well as Muricella (Louie and Randall, 2003). This species appears to pick food more from the water column or from the surface of the coral than the polyps and is more active than H. bargibanti, making it perhaps, a better husbandry candidate (C. Delbeek, pers. obs. 1998; Lourie and Randall, 2003). Kuiter (2003) has recently described what could be a third species of pygmy seahorse, H. colemani form Lord Howe Island, Australia.
Collection and Transport
While on a trip to southern Japan in September of 2003, the Waikiki Aquarium was fortunate to have the chance to acquire two pieces of Muricella plectana and two specimens of H. bargibanti from local collectors. These were collected using small collecting bottles for the seahorses, at a depth of about 50 m (~120 ft.). The seahorses were brought up slowly (several hours) from that depth by line to the collecting boat and taken back to shore. The seahorses were shipped separately from the gorgonians directly from the collection site to the exporter where one of us (JCD) took delivery when they arrived. The gorgonians were then immediately packed separately with seawater and oxygen (50:50) and each of the seahorses was placed in its own shipping bag with water and oxygen (50:50) with a volume of about 2 liters. In addition, thin PVC rod (2mm dia.) was folded into a pretzel shape and placed in each shipping bag. This provided a hitching post for the seahorses, so that they would not tire themselves by having to remain in the water column by continually swimming.
After a return trip to Hawaii of about 12 hours (packing, holding and flight time) the gorgonians were added to a 15 gallon glass holding tank that was plumbed as an open system. An airstone was used for circulation and the water temperature was 78 oF. The seahorses arrived in good condition, were added to the gorgonians, and immediately reattached themselves. The polyps of the gorgonian began to extend themselves in a few hours and all appeared well. For the next three days, the gorgonians were observed to release eggs each day for about an hour. At first, this created some excitement but then it soon became apparent that this was most likely a response to stress, possibly shipping but more likely the warmer water temperature. The seahorses were seen to move from branch to branch and orient themselves in a variety of positions as they carefully searched every square millimeter of the corals surface.
Photo 2. Hippocampus bargibanti at the Waikiki Aquarium exhibiting ist typical behaviour … searching the gorgonian, Muricella plectana, for food. N. Chan
We fed a variety of foods to the system. Live Artemia nauplii, live Euterpina acutifrons, copepods (adults and naupilli), live rotifers Branchionus plicatilis, frozen Cyclop-eeze copepods and live phytoplankton (Chaetoceros gracilis and Tetraselmis chuii). We also made a “mash” consisting of clams, shrimp, fish, phytoplankton and powdered Spirulina algae. Feedings were done every other day with one, some, or all of the food items. Despite these foods, the Muricella slowly began to loose tissue. By early December, fully 90% of the tissue had been lost. However, during this time, the seahorses appeared to be doing well. Due to the small size of the fish and the food items used, it was difficult to directly observe any feeding. However, using a hand magnifying glass they were observed to consume Artemia that had been trapped by the tentacles of the polyps (N. Chan, pers. obs.). We assume they also consumed the copepods and rotifers in a similar manner but we could not verify this. On December, 10th, we found the smaller of the two seahorses dead. At the time of this writing (December, 17th, 2003), the second seahorse is still alive. We hope to receive a few more pieces of Muricella in the new year and plan to construct a better holding system for the corals. This will again consist of an open system but a sump will be constructed to allow a chiller to be installed. Several powerheads will also be used to create stronger flows that can be alternated via timers. We hope that this will allow us to address two of the major factors that were not handled well by the current system namely water temperature and water motion. As was mentioned previously, we believe the key to keeping H. bargibanti is the successful husbandry of its host coral, Muricella. We hope that we will have better success with the next Muricella specimens before we attempt to obtain any more pygmy seahorses. There fore, our advice to any institution that is interested in obtaining these unique seahorses is to first ensure that you can keep Muricella alive, without tissue loss, for several months before even entertaining the notion of obtaining these unique and uncommon seahorses.
Fabricius, K. and P. Alderslade. 2001. Soft Corals and Sea Fans: A Comphrehensive Guide to the Tropical Shallow-water genera of the Central-West Pacific, the Indian Ocean and the Red Sea. AIMS, Townsville, Queensland, Australia, 264 pp.
Kuiter, R.H. 2001. Revision of the Australian seahorses of the genus Hippocampus (Syngnathiformes: Syngnathidae) with descriptions of nine new species. Records of the Australian Museum. 53: 293-340.
Kuiter, R. 2003. A new pygmy seahorse (Pisces: Syngnathidae: Hippocampus) from Lord Howe Island. Records of the Australian Museum (2003) Vol. 55: 113–116. (In Press).
http://www.amonline.net.au/pdf/publications/1382.pdf (first page only)
Lourie, S.A. and J.E. Randall. 2003. A new pygmy seahorse, Hippocampus denise (Teleostei: Sygnathidae), from the Indo-Pacific. Zoological Studies 42(2):284-291.
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