The natural recruitment and recovery process of corals at Green Island

The hard coral community at Green Island Reef is in the early stages of recovery following major damage caused from predation by Acanthaster between 1979 and 1981. Five years after the outbreak, in 1985, the coral community was dominated by juvenile corals mainly of the family Acroporidae. Of 20 sites surveyed by line transect, only 5 had a hard coral cover greater than 10%. Some Pocillopora damicornis was apparently undamaged by A. planci, and some staghorn Acropora thickets were regenerating from small parts of colonies which escaped predation. There was no significant change in hard coral cover at any of 12 sites resurveyed one year later in 1986. The absence of an increase in hard coral cover over the one year period is probably partly due to the early successional stage of the coral community, but it might also be partly attributable to the effects of Cyclone Winifred which passed through the area in February 1986

The effects of increased sedimentation on the recruitment and population dynamics of juvenile corals at Cape Tribulation, North Queensland

The aims of this study were to investigate the effects of increased sedimentation on the early life history stages of the corals, i.e. coral recruitment onto settlement plates and the recruitment and mortality of small corals. The region was divided into three zones which were predicted to be affected by the construction of the road to varying degrees. Two reefs were studied in each of the three zones, and the coral population parameters were compared among the zones

The John Brewer Reef floating hotel : a case-study in marine environmental monitoring : proceedings of a GBRMPA workshop reviewing the environmental monitoring program, held in Townsville, Australia in December 1989

Although the John Brewer Reef Floating Hotel remained in operation for only one year from March 1988, its construction and installation triggered a major environmental assessment and monitoring program which was innovative in many ways. First, the hotel was the first of its kind in the world so the potential impacts were largely unknown and, second, there was increasing community pressure for comprehensive assessments of environmental impacts given the high conservation value placed on the Great Barrier Reef Marine Park - a World Heritage Area. As a result, the environmental impact assessment and monitoring procedure which was implemented was probably the most complex that had been attempted for a project of that scale in Australia and proved, in many ways, to be a pilot for studies within the Great Barrier Reef Marine Park since then. The program involved many individuals and several institutions working in areas such as oceanography, water quality, biological monitoring and social impact studies, with the program coordinated by the Centre for Coastal Management at the University of New England - Northern Rivers (then known as the Northern Rivers College of Advanced Education) on behalf of the proponent

Reproductive biology of three congeneric sea cucumber species, holothuria atra, h. Impatiens and h. edulis, at heron reef, great barrier reef

Three Holothuria species at Heron Reef showed considerable variation in reproductive seasonality, magnitude of gonad index, egg size and numbers, and frequency of asexual reproduction by transverse binary fission. H. atra from the shallow lagoon spawned biannually (in summer and winter), females produced a large number of small ova, and asexual reproduction was frequent. H. impatiens from the reef flat spawned annually in late spring or summer, with females producing a small number of large ova; signs of asexual reproduction were never observed. H. edulis from the deep lagoon showed no annual reproductive pattern, produced an intermediate size and number of eggs, and reproduced asexually moderately frequently. Preliminary results indicated that reproductive maturation and magnitude of gonad index might vary between sites for H. atra. There was little temporal overlap in spawning by the three species at the sites sampled, and this may be a factor in the maintenance of their genetic isolation

Reproductive seasonality, settlement, and post-settlement mortality of Pocillopora damicornis (Linnaeus), at Lizard Island, Great Barrier Reef

Pocillopora damicornis (Linnaeus) has seasonal gametogenesis and planula release at Lizard Island, Great Barrier Reef, in contrast with several previous reports on the species at other locations. The number of planulae released and gonad development varied considerably among colonies sampled at the same time, but reproductive activity occurred predominantly in winter. P. damicornis planulae settled preferentially on algal-covered substrata, rather than bare coral substrata, but showed subsequent mortality inversely related to this settlement preference. Competition with algae and biological disturbance contribute to spat mortality at different stages of settlement and growth

Reproductive ecology of four scleratinian species at Lizard Island, Great Barrier Reef

Reproductive ecology of four scleractinian species, Lobophyllia corymbosa, Favia favus, Porties lutea and Porites australiensis was studied for two years on a patch reef near Lizard Island. Two major reproductive patterns were found: L. corymbosa and F. favus were simultaneous hermaphrodites and released gametes over several days in summer; and P. lutea, and P. australiensis were dioecious and released gametes over several weeks to several months respectively, in summer. Three of the four species spawned predominantly in the lunar period between the full and last quarter moon. In all four species, ovaries began developing several months earlier than testes. Number of ova per colony varied greatly amongst the species and was inversely related to mature egg size. The results presented here contrast with earlier assumptions of almost uniform viviparity of corals and supports the generalization that a brief annual spawning period with larvae developing externally may prove to be the dominant form of sexual reproduction in hermatypic corals

Response of Antarctic terrestrial microarthropods to long-term climate manipulations

The terrestrial biota of the Antarctic Peninsula region are experiencing marked changes in climate, especially rising temperatures, precipitation, and UV-B radiation-a combination unique worldwide. These changes, combined with the inherent simplicity of terrestrial communities, have led to their use as "model systems" to predict the future climate change responses of biota at lower latitudes. However, studies integrating responses at different levels of the community trophic structure are lacking. We report here the consequences on the soil microarthropod community of a four-year, multivariate, climate-manipulation experiment carried out over vegetation near Palmer Station, Anvers Island, western Antarctic Peninsula. The experiment used a multifactorial randomized-block design, deploying filters to raise temperatures and reduce ultraviolet (UV)-B (280-320 nm) or both UV-B and UV-A (320-400 nm) radiation of existing vegetation, with further water and fertilizer amendment treatments. Seven microarthropod species recovered in sufficient numbers for statistical analyses showed considerable spatial aggregation independent of treatment, a feature typical of many soil invertebrates. Analyses using negative binomial generalized linear modeling identified further significant and consistent treatment impacts on both individual species and species groups. Relative to controls, manipulations increasing temperature decreased numbers of microarthropods (particularly Collembola), as did exposure to near-ambient levels of UV radiation (separate significant effects for both UV-A and UV-B), while water amendment increased numbers. The impacts of temperature and water are consistent with our understanding of the importance of these two environmental variables and their interaction in Antarctic terrestrial ecosystems. The negative impact of UV (-A or -B) on arthropod heterotroph and detritivore populations in the Antarctic terrestrial food web is likely to be a secondary consequence of UV impact on vegetation characteristics. This is, again, consistent with general predictions of the impact of changing UV climate on ecosystem function

Reef development at high-latitudes during multiple interglacial cycles: New evidence from Lord Howe Island, southwestern Pacific

Reef development during past Interglacial periods, when sea level and sea surface temperatures were higher than today, provide unique insights into how reef systems may respond to projected human-induced global warming. Lord Howe Island currently represents the southernmost limit of reef development in the Pacific. Reef growth of Pleistocene age has been inferred to have occurred around the island, and this paper provides the first detailed descriptions on the character of this development. Two phases of reef growth are identified, which occurred as isolated fringing reefs along the edge of the basaltic hills of the island. Uranium-series dating indicates that the upper part of the sequence is of Last Interglacial age, however extensive calcite recrystallisation meant the lower part of the sequence does not yield reliable ages. Calcite cements suggest that several phases of recrystallisation have occurred meaning the lower part of the sequence is most likely to represent reef of Penultimate Interglacial age. Component analysis of the sedimentary matrix within the reef indicates coralline algae dominated sands which are very similar to the modern reef environment. This suggests that the environment at Lord Howe Island has remained at or close to the environmental limits for reef growth during the past few interglacials, despite lithospheric plate motion moving this island further north into reef building seas