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1.
Spatial, temporal and habitat-related variation in the abundance of large predatory fish at One Tree Reef, Australia 总被引:1,自引:1,他引:0
Patterns of abundance of large piscivorous fish (>200 mm TL) were documented at two spatial and four temporal scales within
the main lagoon of One Tree Reef on Australia’s Great Barrier Reef. Grouper (Serranidae), snapper (Lutjanidae) and wrasses
(Labridae) were the most abundant large piscivores. On a large scale (hundreds of metres), patterns of predator abundance
were consistently greater on the inner edge than centre of the lagoon over a range of temporal scales: days, weeks, months
and years. On a small spatial scale (tens of metres), the abundance of large predatory fish was patchy. At both spatial scales,
fish were consistently aggregated in particular areas and associated with specific structural features of the reef habitat.
Predator abundance was high where live corals were predominant and the topography was more complex. Hence, predation pressure
and its potential effects on the distribution and abundance of prey populations, both in time and space, may vary greatly
within lagoonal environments.
Accepted: 25 May 1997 相似文献
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Trap sampling over reefs in deep (mean = 20 m) and shallow (mean = 10 m) waters along c. 1500 km of coastline in tropical north‐western Australia during both day and night and in wet and dry periods yielded 23 377 fishes, representing 32 families, 58 genera and 119 species. Individuals of the Serranidae, Lutjanidae, Lethrinidae and Carangidae contributed 88·9% to the total catch. The ichthyofaunal compositions of the Kimberley, Canning and Pilbara bioregions were relatively discrete. Species composition was influenced far more by location (latitude) than by water depth, period and time of day, and underwent a gradational change southwards. The latter change reflected differences in the trends exhibited by the relative abundances of certain species with increasing latitude and the confinement of other species largely to particular regions. The three most abundant species, i.e. Lethrinus sp. 3, Lutjanus carponotatus and Lethrinus laticaudis contributed 34·8, 20·8 and 11·6% to the total catch, respectively. The first species was rarely recorded in the two most northern locations and was abundant in the four most southern locations, whereas the last two species were relatively more abundant in northern than in southern locations. Lutjanus bitaeniatus and Lutjanus johnii were found exclusively at the two locations in the Kimberley region, whereas Abalistes stellatus, Pentapodus emeryii and Lethrinus nebulosus were not caught in this region but were found in both locations of the Canning and Pilbara regions. The species composition in deep and shallow waters at each location almost invariably differed significantly between day and night and between dry and wet periods, with species such as L. bitaeniatus, L. johnii, Lutjanus sebae and A. stellatus being more abundant over deep reefs, whereas L. carponotatus, L. laticaudis, Siganus fuscescens and Lethrinus lentjan were more numerous over shallow reefs. Species such as L. johnii and Lethrinus atkinsoni were relatively more important in night‐time than daytime catches, whereas the reverse applied to Lethrinus lentjan, L. laticaudis and Choerodon cyanodus. Lethrinus sp. 3 and L. laticaudis were relatively more important in catches during the dry than wet period. 相似文献
5.
Global species delimitation and phylogeography of the circumtropical ‘sexy shrimp’ Thor amboinensis reveals a cryptic species complex and secondary contact in the Indo‐West Pacific 下载免费PDF全文
6.
Coral reefs are generally considered to be the most biologically productive of all marine ecosystems, but in recent times these vulnerable aquatic resources have been subject to unusual degradation. The general decline in reefs has been greatly accelerated by mass bleaching in which corals whiten en masse and often fail to recover. Empirical evidence indicates a coral reef bleaching cycle in which major bleaching episodes are synchronized with El Niño events that occur every 3–4 years on average. By heating vast areas of the Pacific Ocean, and affecting the Indian and Atlantic Oceans as well, El Niño causes widespread damage to reefs largely because corals are very sensitive to temperature changes. However, mass bleaching events were rarely observed before the 1970s and their abrupt appearance two decades ago remains an enigma. Here we propose a new explanation for the sudden occurrence of mass bleaching and show that it may be a response to the relative increase in El Niño experienced over the last two decades. 相似文献
7.
After c. 30 years without sighting or capture, Anthias salmopunctatus was rediscovered at the type locality, St Peter and St Paul's Rocks, Mid-Atlantic Ridge. To date, the known distribution is restricted to depths varying from 35 to 55 m in vertical drop offs around the perimeter of the islands ( c. 400 m). This may be the smallest geographic range known for a marine fish species. 相似文献
8.
Claude E. Payri Stéphane Maritorena Christophe Bizeau Michel Rodière 《Journal of phycology》2001,37(2):223-234
Pigment concentration, in vivo absorption, and photosynthetic parameters of the coralline alga Hydrolithon onkodes (Heydrich) Penrose and Woelkerling were compared among samples from a lagoon and from a reef crest of Tahiti Island. Four groups of specimens were considered, differing in their natural exposure to PAR. For specimens collected from the lagoon, the tissues from low-light samples had significantly higher pigment concentration, particularly chl a and phycobilins, compared with the high-light exposed plants that contained more total carotenoids. The in vivo absorption spectra normalized to chl a (called a* values) also revealed differences. The low-light samples had a reduced absorption capacity and a well-marked phycobilin absorption signature, whereas sunlit samples showed a greater absorption at wavelengths absorbed mainly by chl a and carotenoids. The decrease of a* when pigment concentration increased is interpreted as a consequence of the pigment packaging. Significantly lower α (chlorophyll basis) and higher Ek values were found in the shaded plants. The values of P max for the four groups of specimens were not significantly different. The samples showed various degrees of photoinhibition depending on the light exposure during growth, and this effect was more pronounced in the shaded plants. The specimens from the reef crest deviate from the general model presented for the lagoon samples and show a mix of sun- and shade-exposed characteristics. We have shown that the coralline alga H. onkodes responds to its light environment, probably by acclimation rather than ecotypic genetic variation, by adjusting its physiology, but some morphological differences are also involved. Photoacclimation can explain partly the wide distribution of this species over the reef ecosystem and its major contribution to the building of the reef. 相似文献
9.
Shape analysis of two sympatric coral species: Implications for taxonomy and evolution 总被引:1,自引:0,他引:1
JOHN M. PANDOLFI COLLETTE DICK BURKE 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1989,22(2):183-193
Fourier shape analysis of Pleurodictyum americanum and P. dividua , favositid tabulate corals, from the Middle Devonian Hamilton Group of New York State, indicates that colony growth form is variable within species between environments, but that the range of variability in growth form is static through time. Pleurpdictyum dividua displays a columnar morphotype; however, P. dividua and P. americanum cannot be discriminated from one another based on colony shape alone. A major prediction of the punctuated equilibrium model of evolution is morphological stasis throughout the duration of a species. Harmonic means of assemblages of P. americanum show no persistent temporal trends. The range of harmonic means present among the oldest assemblages (Centerfield Limestone) are comparable to those among the youngest assemblages (Windom Shale) and to those in the intervening intervals. Character stasis in colony growth form lasted throughout a 2.5-3.5 my interval. In tabulate corals, where reproductive modes such as fragmentation have not been demonstrated, growth form may be useful in interpreting ancient environments. In addition, the tempo of evolution of growth form can be analyzed when sufficient morphological data are available from a wide distribution of environments. Thus, Fourier shape analysis of growth form provides a powerful tool for paleontologists to interpret the ecology and evolution of colonial marine animals. 相似文献
10.
The fossil record of the Pomacentridae has been based on species from six genera. The status of these taxa is reviewed. Only two are tentatively accepted as belonging to the Pomacentridae: Chromis savomini from the Miocene of Algeria and Izuus nakamurai from the Miocene of Japan. In addition, a new genus and species Palaeopomacentrus orphae is described from the lower Middle Eocene of Monte Bolca, Northern Italy. This is the first substantiated record of a pomacentrid from the Eocene, and represents the oldest record of the family. 相似文献