The occurrence of black corals in Jamaican reef environments, with special reference to Stichopathes lutkeni (Antipatharia: Antipathidae)

The purpose of this study was to record the species of Antipatharia on Jamaican reefs and to carry out limited studies on densities and sizes of the common species.In addition,a cliff face created by dredging in 2002 provided the opportunity to study growth of newly settled colonies.Observations since 1998 and measurements since 2001 were made using SCUBA at depths down to 35 m.Seven species of Antipatharia were observed on steep coral reef escarpments below 25 m depth.The commonest species was the unbranched "wire coral " Stichopathes lutkeni .Other common species included the fan-shaped black corals Antipathes atlantica and A. gracilis .Frequently encountered species included commercially important A.caribbeana and a species with an unusual,scrambling growth form, A. rubusiformis.The other major commercial species in the Caribbean, Plumapathes pennacea ,and a cave-dwelling species,A.umbratica ,were rarely observed.Greatest black coral abundance occurred on steep slopes of hard substrata in low light intensity but exposed to the long-shore current. Combined densities of the commoner Antipatharia at 30 m deep at Rio Bueno on the north coast,ranged from 0.1 to 2.5 m-2 (eleven 10 m x 1 m belt transects,1-25 colonies per transect,68 colonies in total).Forty-six of the 68 colonies were S.lutkeni ,while nearby at Discovery Bay at 30-35 m,55 out of 59 colonies were S.lutkeni. There was a significant difference between the mean length of colonies in these two populations of S.lutkeni (100 cm and 80 cm,respectively),probably relating to habitat.A third population of S.lutkeni growing at 15-20 m deep on the recently dredged cliff had a much smaller mean length of 36.6 cm (n=27).The largest individual measured 83 cm long,indicating a minimum growth rate of the unbranched corallum of 2.1 mm per day

The occurrence of black corals in Jamaican reef environments, with special reference to Stichopathes lutkeni (Antipatharia: Antipathidae).

The purpose of this study was to record the species of Antipatharia on Jamaican reefs and to carry out limited studies on densities and sizes of the common species. In addition, a cliff face created by dredging in 2002 provided the opportunity to study growth of newly settled colonies. Observations since 1998 and measurements since 2001 were made using SCUBA at depths down to 35 m. Seven species of Antipatharia were observed on steep coral reef escarpments below 25 m depth. The commonest species was the unbranched "wire coral" Stichopathes lutkeni. Other common species included the fan-shaped black corals Antipathes atlantica and A. gracilis. Frequently encountered species included commercially important A. caribbeana and a species with an unusual, scrambling growth form, A. rubusiformis. The other major commercial species in the Caribbean, Plumapathes pennacea, and a cave-dwelling species, A. umbratica, were rarely observed. Greatest black coral abundance occurred on steep slopes of hard substrata in low light intensity but exposed to the long-shore current. Combined densities of the commoner Antipatharia at 30 m deep at Rio Bueno on the north coast, ranged from 0.1 to 2.5 m(-2) (eleven 10 m x 1 m belt transects, 1-25 colonies per transect, 68 colonies in total). Forty-six of the 68 colonies were S. lutkeni, while nearby at Discovery Bay at 30-35 m, 55 out of 59 colonies were S. lutkeni. There was a significant difference between the mean length of colonies in these two populations of S. lutkeni (100 cm and 80 cm, respectively), probably relating to habitat. A third population of S. lukeni growing at 15-20 m deep on the recently dredged cliff had a much smaller mean length of 36.6 cm (n= 27). The largest individual measured 83 cm long, indicating a minimum growth rate of the unbranched corallum of 2.1 mm per day.

Effects of dieldrin on life stages of the African catfish, Clarias gariepinus (Burchell).

Early life stages of Clarias gariepinus were found to be less sensitive to acute dieldrin toxicity than were those of Nile tilapia, Oreochromis niloticus; 96-h LC50 values for 37-day-old fry were 11. 7 and 4.95 microg liter-1, respectively. The growth of C. gariepinus fry was unaffected by 30 days of exposure to 2.4 microg liter-1 dieldrin under static conditions with water renewal every 96 h, whereas growth of O. niloticus fry was significantly reduced. Adult C. gariepinus exposed to dieldrin for 30 days, with water changes every 96 h, rapidly absorbed dieldrin from aqueous solution. Dieldrin concentration was measured just before water changes and from an initial concentration of 4.0 microg liter-1, stabilized after 12 days at about 0.075 microg liter-1, indicating that a balance between uptake and excretion and metabolism had been achieved. Dieldrin accumulated in the tissues during these exposures, especially in the liver, where after 30 days the bioconcentration factor relative to initial concentration was about 900. Chronic exposure of C. gariepinus to dieldrin had no effect on blood hematocrit and hemoglobin, but appeared to slow the growth of catfish and had a clear negative effect on the reproductive potential of mature females.

Biosynthesis of the antibiotic 2,5-dihydrophenylalanine by Streptomyces arenae.

The biosynthesis of L-2,5-dihydrophenylalanine (DHPA) in Streptomyces arenae strain Tü 109 was studied in tracer experiments with [U-14C]- and [1,6-14C]shikimic acid followed by chemical degradation of the labeled product. The results indicate that shikimic acid (II) provides only the ring carbons of DHPA, that the side chain of DHPA is attached at the carbon derived from C-1 of II, and that in the transformation of II into DHPA the asymmetry of the ring of II is preserved, with C-6 of II giving rise to C-6' of DHPA. Both generally 14C-labeled chorismate and prephenate, but not L-[3-14C]serine, are incorporated into DHPA. By preparing and feeding 5,6-dihydro[4-3H]prephenate it was shown that this compound is not an intermediate in the biosynthesis of DHPA. A reaction sequence is proposed for the conversion of prephenate to DHPA, involving an allylic rearrangement, followed by 1,4 reduction of the resulting conjugated diene and a combined decarboxylation/dehydration.