Ecological and conservation significance of the subtidal rocky reef communities of northern New South Wales, Australia

1999 ◽  
Vol 50 (4) ◽  
pp. 299 ◽  
Author(s):  
Vicki J. Harriott ◽  
Simon A. Banks ◽  
Roland L. Mau ◽  
Darren Richardson ◽  
Lisa G. Roberts

The subtropical rocky reefs of Cook Island, Julian Rocks and the South West Rocks area form part of a chain of islands and reefs with significant coral cover from the Queensland border (28˚S) to the southern extent of extensive coral communities in coastal Australia (31˚S). Benthic communities at 18 subtidal sites at the three localities were surveyed quantitatively by video-transects, and coral species lists were compiled. Twenty-eight coral species previously unrecorded for these localities were identified, increasing the species richness of hermatypic corals reported for the northern NSW region (excluding the Solitary Islands) from 14 to 43. Coral species richness declined with latitude. Benthic communities were generally dominated by turfing and macroalgal species, with Pyura, sponges, and barnacles locally abundant. Scleractinian coral cover ranged from 0% to 42.6% per site, with highest coral cover at the most southern site. Julian Rocks is a designated Aquatic Reserve, and Marine Parks have been suggested for all three localities. Selection of Marine Protected Areas requires information on their ecological significance. These surveys report the first quantitative information on the shallow- water, rocky-reef communities in the region, which is a vital step in assessing their ecological significance.

1995 ◽  
Vol 46 (8) ◽  
pp. 1137 ◽  
Author(s):  
SA Banks ◽  
VJ Harriott

The Gneering Shoals and Mudjimba Island are coastal rocky-reef communities approximately 250 km south of the Great Barrier Reef. Ten sites from 700 m to 12 km offshore were investigated with the use of video-transects to determine percentage cover of benthic organisms. The marine benthic communities were dominated by hard corals, soft corals and turf algae. Three community types were identified: (1) offshore communities, (2) island-associated communities, and (3) a nearshore algae-dominated community. Inshore sites were dominated by flat encrusting hard corals, whereas offshore sites were dominated by foliose and plating hard corals, particularly Acropora solitaryensis and Turbinaria spp. There was a notable scarcity of branching species, particularly from the Family Acroporidae. Seventy-seven species of scleractinian coral, representing 30 genera in 11 families, have been recorded from the Gneering Shoals region. The Gneering Shoals had low coral species richness relative to the southern Great Barrier Reef (244 species) and Flinders Reef, 50 km to the south-east (118 species). Possible explanations for the relatively low coral species richness in the Gneering Shoals region include the physical attributes of the site and the hypothesized failure of the East Australian Current to be a major influence on the region.


1997 ◽  
Vol 45 (1-2) ◽  
pp. 35-43 ◽  
Author(s):  
Roberto Villaça ◽  
Fábio B. Pitombo

The benthic communities of fringing and mushroom-shaped shallow-water reefs of the Abrolhos region (southern coast of Bahia) were surveyed. Line transects were used to estimate coral and algal percentage cover. Mussismilia braziliensis is the most conspicuous coral species in the majority of the communities surveyed, but turf algal make up the dominant cover in all but one studied reef. In general, communities on mushroom-shaped reefs have higher diversity and higher coral cover than on fringing reefs. For both reef morphologies, the coral to alga cover ratio does. not show marked differences between annual surveys, despite the high productivity characteristic of the dominant algal species.


1999 ◽  
Vol 50 (5) ◽  
pp. 427 ◽  
Author(s):  
R. van Woesik ◽  
T. Tomascik ◽  
S. Blake

Benthic communities were assessed and 22 environmental variables were monitored at seven leeward localities (L1ŒL7) in the Whitsunday Islands, Queensland, Australia. L1 was near the Proserpine and O’Connell river mouths and L7 ~80 km north of the river mouths. Distinct physico Œchemical and biological gradients were evident. Sparse scleractinian coral communities, dominated by faviids, Montipora spp. and encrusting Porites colonies, were present at L1, L2 and L3, whereas diverse reef-building communities, dominated by Acropora spp., were more common at and beyond L4. The number of coral recruits (age <6 months) did not differ significantly among localities, suggesting that coral recruitment was near random and that the environment shapes the adult community from those recruits. The study demonstrates strong negative relationships between chlorophyll a and the following: percentage coral cover, coral species richness and coral abundance. The reef-building capacities of the coral communities and the extent of Holocene reef development were inconsistent at L2 and L3, which is interpreted as a sign of anthropogenic effects.


2007 ◽  
Vol 343 ◽  
pp. 77-85 ◽  
Author(s):  
JI Sonnenholzner ◽  
LB Ladah ◽  
KD Lafferty

2021 ◽  
Author(s):  
Christopher Jury ◽  
Keisha Bahr ◽  
Evan Barba ◽  
Russell Brainard ◽  
Annick Cros ◽  
...  

Abstract Coral reefs are among the most sensitive ecosystems affected by ocean acidification and warming, and are predicted to shift from net accreting calcifier-dominated systems to net eroding algal-dominated systems over the coming decades. Here we present a long-term experimental study examining the responses of entire mesocosm coral reef communities to acidification (-0.2 pH units), warming (+ 2°C), and combined future ocean (-0.2 pH, + 2°C) treatments. We show that under future ocean conditions, net calcification rates declined yet remained positive, corals showed reduced abundance yet were not extirpated, and community composition shifted while species richness was maintained. Our results suggest that under Paris Climate Agreement targets, coral reefs could persist in an altered functional state rather than collapse.


2021 ◽  
Vol 8 ◽  
Author(s):  
Juan L. Torres-Pérez ◽  
Carlos E. Ramos-Scharrón ◽  
William J. Hernández ◽  
Roy A. Armstrong ◽  
Maritza Barreto-Orta ◽  
...  

Land-based sediment stress represents a threat to many coral reefs in Puerto Rico primarily as a result of unrestricted land cover/land use changes and poor best management practices. The effects of such stresses have been documented along most coasts around the island. However, little attention has been paid to reefs located on the north coast, and very little is known about their composition and current state. Here, we present a study characterizing riverine inputs, water quality conditions, and benthic composition of two previously undescribed coral reefs (Tómbolo and Machuca reefs) located just eastward of the Río Grande de Manatí outlet in north-central Puerto Rico. This study utilizes a time series of remotely sensed ocean color products [diffuse vertical attenuation coefficient at 490 nm (Kd490) and chlorophyll-a concentration (Chl-a) estimated with data from the Visible Infrared Imaging Radiometer Suite (VIIRS)] to characterize water quality in this coastal region. In general, the months with relatively high mean daily river streamflow also coincide with months having the highest proportion of eastward wave direction, which can promote the eastward influence of river waters toward the two coral reefs sites. Kd490 and Chl-a showed a higher riverine influence closer to the watershed outlet. Kd490 and Chl-a monthly peaks also coincide with river streamflow highs, particularly at those pixels closer to shore. Tómbolo Reef, located farther eastward of the river outlet, shows a well-developed primary reef framework mainly composed of threatened reef-building species (Acropora palmata, Pseudodiploria) and high coral cover (19–51%). The benthos of Machuca Reef, located closer to the river outlet, is dominated by macroalgae with a significantly lower coral cover (0.2–2.7%) mainly composed of “weedy” coral species (Porites astreoides and Siderastrea radians). Cover of major benthic components correlates with distance from the river outlet, and with gradients in Kd490 and Chl-a, with higher coral cover and lower macroalgal cover farther from the river outlet. Coral cover at Tómbolo Reef is higher than what has been reported for similar sites around Puerto Rico and other Caribbean islands showing its ecological importance, and as up until now, an unrecognized potential refuge of reef-building threatened coral species.


2019 ◽  
Vol 15 (10) ◽  
pp. 20190493 ◽  
Author(s):  
T. Edward Roberts ◽  
Sally A. Keith ◽  
Carsten Rahbek ◽  
Tom C. L. Bridge ◽  
M. Julian Caley ◽  
...  

Natural environmental gradients encompass systematic variation in abiotic factors that can be exploited to test competing explanations of biodiversity patterns. The species–energy (SE) hypothesis attempts to explain species richness gradients as a function of energy availability. However, limited empirical support for SE is often attributed to idiosyncratic, local-scale processes distorting the underlying SE relationship. Meanwhile, studies are also often confounded by factors such as sampling biases, dispersal boundaries and unclear definitions of energy availability. Here, we used spatially structured observations of 8460 colonies of photo-symbiotic reef-building corals and a null-model to test whether energy can explain observed coral species richness over depth. Species richness was left-skewed, hump-shaped and unrelated to energy availability. While local-scale processes were evident, their influence on species richness was insufficient to reconcile observations with model predictions. Therefore, energy availability, either in isolation or in combination with local deterministic processes, was unable to explain coral species richness across depth. Our results demonstrate that local-scale processes do not necessarily explain deviations in species richness from theoretical models, and that the use of idiosyncratic small-scale factors to explain large-scale ecological patterns requires the utmost caution.


Paleobiology ◽  
2019 ◽  
Vol 45 (4) ◽  
pp. 652-675 ◽  
Author(s):  
Jonathan B. Antcliffe ◽  
William Jessop ◽  
Allison C. Daley

AbstractArchaeocyaths are the most abundant sponges from the Cambrian period, having formed the first animal reef communities more than 500 million years ago. The Archaeocyatha are index fossils for correlating rocks of similar ages globally because of their abundance, extensive geographic distribution, detailed anatomy, and well-established taxonomy. Their ecological significance remains incompletely explored, yet they are known to have strongly competitively interacted, unlike modern sponges. This study examines the feeding ecology of the fossil remains of Siberian archaeocyath assemblages. As suspension feeders, archaeocyaths filtered plankton from the water column through pores in their outer wall. Here we outline a new method to estimate the limit on the upper size of plankton that could be consumed by an archaeocyath during life. The archaeocyaths examined were predominantly feeding on nanoplankton and microplankton such as phytoplankton and protozooplankton. Size-frequency distributions of pore sizes from six different Siberian archaeocyath assemblages, ranging from Tommotian to Botoman in age, reveal significantly different upper limits to the prey consumed at each locality. Some of the assemblages contain specimens that could have fed on larger organisms extending into the mesoplankton, including micro-invertebrates as a possible food resource. These results show that during the establishment of the first animal reef systems, prey partitioning was established as a way of reducing competition. This method has applicability for understanding the construction and the functioning of the first reef systems, as well as helping to understand modern reef systems and their development though time and space.


2015 ◽  
Vol 12 (2) ◽  
pp. 365-372 ◽  
Author(s):  
S. Comeau ◽  
R. C. Carpenter ◽  
C. A. Lantz ◽  
P. J. Edmunds

Abstract. Ocean acidification (OA) poses a severe threat to tropical coral reefs, yet much of what is know about these effects comes from individual corals and algae incubated in isolation under high pCO2. Studies of similar effects on coral reef communities are scarce. To investigate the response of coral reef communities to OA, we used large outdoor flumes in which communities composed of calcified algae, corals, and sediment were combined to match the percentage cover of benthic communities in the shallow back reef of Moorea, French Polynesia. Reef communities in the flumes were exposed to ambient (~ 400 μatm) and high pCO2 (~ 1300 μatm) for 8 weeks, and calcification rates measured for the constructed communities including the sediments. Community calcification was reduced by 59% under high pCO2, with sediment dissolution explaining ~ 50% of this decrease; net calcification of corals and calcified algae remained positive but was reduced by 29% under elevated pCO2. These results show that, despite the capacity of coral reef calcifiers to maintain positive net accretion of calcium carbonate under OA conditions, reef communities might transition to net dissolution as pCO2 increases, particularly at night, due to enhanced sediment dissolution.


Ecology ◽  
2013 ◽  
Vol 94 (7) ◽  
pp. 1636-1646 ◽  
Author(s):  
Jarrett E. K. Byrnes ◽  
Bradley J. Cardinale ◽  
Daniel C. Reed

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