Nitrogen ecophysiology of Heron Island, a subtropical coral cay of the Great Barrier Reef, Australia

2004 ◽  
Vol 31 (5) ◽  
pp. 517 ◽  
Author(s):  
Susanne Schmidt ◽  
William C. Dennison ◽  
Gordon J. Moss ◽  
George R. Stewart

Coral cays form part of the Australian Great Barrier Reef. Coral cays with high densities of seabirds are areas of extreme nitrogen (N) enrichment with deposition rates of up to 1000 kg N ha–1 y–1. The ways in which N sources are utilised by coral cay plants, N is distributed within the cay, and whether or not seabird-derived N moves from cay to surrounding marine environments were investigated. We used N metabolite analysis, 15N labelling and 15N natural abundance (δ15N) techniques. Deposited guano-derived uric acid is hydrolysed to ammonium (NH4+) and gaseous ammonia (NH3). Ammonium undergoes nitrification, and nitrate (NO3–) and NH4+ were the main forms of soluble N in the soil. Plants from seabird rookeries have a high capacity to take up and assimilate NH4+, are able to metabolise uric acid, but have low rates of NO3– uptake and assimilation. We concluded that NH4+ is the principal source of N for plants growing at seabird rookeries, and that the presence of NH4+ in soil and gaseous NH3 in the atmosphere inhibits assimilation of NO3–, although NO3– is taken up and stored. Seabird guano, Pisonia forest soil and vegetation were similarly enriched in 15N suggesting that the isotopic enrichment of guano (δ15N 9.9‰) carries through the forest ecosystem. Soil and plants from woodland and beach environments had lower δ15N (average 6.5‰) indicating a lower contribution of bird-derived N to the N nutrition of plants at these sites. The aquifer under the cay receives seabird-derived N leached from the cay and has high concentrations of 15N-enriched NO3– (δ15N�7.9‰). Macroalgae from reefs with and without seabirds had similar δ15N values of 2.0–3.9‰ suggesting that reef macroalgae do not utilise 15N-enriched seabird-derived N as a main source of N. At a site beyond the Heron Reef Crest, macroalgae had elevated δ15N of 5.2‰, possibly indicating that there are locations where macroalgae access isotopically enriched aquifer-derived N. Nitrogen relations of Heron Island vegetation are compared with other reef islands and a conceptual model is presented.

2021 ◽  
pp. 1329878X2110558
Author(s):  
Kerrie Foxwell-Norton ◽  
Claire Konkes

An obituary for the Great Barrier Reef (the Reef) by travel and food writer Rowan Jacobsen (2016) commemorated its ‘lifetime accomplishments’ in Outside, the US outdoor recreational magazine. ‘News’ of the Reef's demise went viral and the economic and political furore that followed was immense. Tourism industries, especially reliant on international arrivals, were impacted as potential visitors accepted the Reef's passing as fact. Politicians scampered to reassure Australians and the globe that the Reef was indeed still alive and beautiful. In the Australian public sphere, climate science deniers, alongside those advocating for climate action, collided over the impacts of global warming to Reef health. Subsequent mass coral bleaching events in 2016, 2017 and 2020 sustained at the very least, the idea that the Reef was, or was soon to be, dead. Our paper follows the idea of a ‘dead Reef’ in the context of historical and recent debates about Reef protection. Using Google Trends, we identify Jacobsen's article as the source of increased Australian and global ideation of a ‘dead Reef’. As a site of local and global environmental communication – where human relations to nature are expressed and understood - the Reef holds extraordinary story telling power. At the current junction then, the way we communicate the Reef is critical to public understanding and political action on climate change. We conclude Jacobsen's article is an example of the problems of satirical communication, serving to amplify existing conflicts and undermine efforts to foster to climate action.


2017 ◽  
Author(s):  
Mikhail V. Matz ◽  
Eric A. Treml ◽  
Galina V. Aglyamova ◽  
Madeleine J. H. van Oppen ◽  
Line K. Bay

AbstractCan genetic adaptation in reef-building corals keep pace with the current rate of sea surface warming? Here we combine population genomic, biophysical modeling, and evolutionary simulations to predict future adaptation of the common coralAcropora milleporaon the Great Barrier Reef. Loss of coral cover in recent decades did not yet have detectable effect on genetic diversity in our species. Genomic analysis of migration patterns closely matched the biophysical model of larval dispersal in favoring the spread of existing heat-tolerant alleles from lower to higher latitudes. Given these conditions we find that standing genetic variation could be sufficient to fuel rapid adaptation ofA. milleporato warming for the next 100-200 years, although random thermal anomalies would drive increasingly severe mortality episodes. However, this adaptation will inevitably cease unless the warming is slowed down, since no realistic mutation rate could replenish adaptive genetic variation fast enough.


1997 ◽  
Vol 48 (4) ◽  
pp. 303 ◽  
Author(s):  
Rufus M. G. Wells ◽  
John Baldwin ◽  
Roger S. Seymour

Concentrations of methaemoglobin (the oxidized non-functional ferric form of haemoglobin) in the blood of marine fish are poorly documented. Although high concentrations have been reported for fish maintained in captivity, baseline values for wild populations are unknown. Two techniques, the cyanide derivative method and the multiple wavelength method, were used to determine methaemoglobin concentrations in blood samples from 25 species of marine teleosts and elasmobranchs captured on the Australian Great Barrier Reef. Although methaemoglobin generally accounted for less than 2% of total haemoglobin, systematic errors occurred when these two standard methods, developed for mammalian blood, were applied to the blood of some fish species. Most problems arose from reactions of various blood components with the reagents used in the cyanide derivative method. Consequently, the multiple wavelength method generally was more reliable for estimating methaemoglobin in the blood of marine fish. The low methaemoglobin concentrations in fish studied on the Great Barrier Reef indicate high water quality and healthy physiological condition.


Cryobiology ◽  
2012 ◽  
Vol 65 (2) ◽  
pp. 157-158 ◽  
Author(s):  
Mary Hagedorn ◽  
Madeleine J.H. van Oppen ◽  
Virginia Carter ◽  
Mike Henley ◽  
David Abrego ◽  
...  

1995 ◽  
Vol 46 (4) ◽  
pp. 707 ◽  
Author(s):  
NA Moltschaniwskyj ◽  
PJ Doherty

This paper describes the cephalopod genera caught with light-traps at different locations and depths in the waters of the central Great Barrier Reef (GBR). Multiple stations were sampled in four locations: (I) the coastal GBR Lagoon, (2) inter-reef passages (Magnetic and Palm), (3) near-reef environments (Keeper, Helix, Faraday and Myrmidon) ranging from mid- to outer-shelf locations, and (4) the Coral Sea. A total of 13 cephalopod genera was caught from monthly cruises conducted from October to January of 1990-91 and 1991-92. Octopus, the most abundant juvenile cephalopod, was present in relatively high numbers at all shelf locations; few were caught in the Coral Sea. Photololigo, the most abundant squid, was rarely caught outside the GBR Lagoon. In contrast, Sthenoteuthis, the second most abundant squid, was caught at all locations. Deep samples from most locations were dominated by Octopus. Abralia was found only near the bottom of the GBR Lagoon; in contrast, Euprymna, the fourth most abundant genus, was collected only at the surface. Cephalopod communities from the GBR Lagoon had higher abundances of Octopus, Photololigo and Abralia compared with communities from the three other areas. Reef passages and reef locations shared similar communities, with the squid component dominated by Sthenoteuthis. Very low numbers of cephalopods were caught in the Coral Sea by light attraction. High concentrations of cephalopods detected in the middle of the GBR Lagoon are consistent with present knowledge about oceanographic processes over this shelf.


1988 ◽  
Vol 39 (1) ◽  
pp. 19 ◽  
Author(s):  
GB Jones ◽  
FG Thomas

Studies carried out over several years on a tropical estuary, the Ross River Estuary, have shown that copper speciation is influenced by both terrestrial and marine humic substances. While terrestrial humic substances are mobilized by high freshwater runoff in the monsoonal season, Trichodesmium blooms mobilize high concentrations of marine humics to the inshore zone and increase labile forms of copper. The marine humics are more soluble than the terrestrial humics and persist in coastal waters of the Great Barrier Reef lagoon for many months prior to the wet season.


1978 ◽  
Vol 29 (3) ◽  
pp. 345 ◽  
Author(s):  
GR Cresswell ◽  
MA Greig

Current meter recordings were made for 18 days at a site near Low Islets in the Great Barrier Reef lagoon and at another site in the nearby Trinity Opening. Hydrological data were collected inside the Barrier Reef and in the adjacent Coral Sea at the start of the experiment. The current records were analysed to gauge the effects of tides, wind, and open ocean circulation features. The lagoon flow was northward with a slight modulation due to the tides. The flow was reduced for several days at a time when there was enhanced eastward flow through Trinity Opening and out to the Coral Sea. The relatively low salinity, cool water in the lagoon is believed to have come from farther south and to have been diluted en route by river runoff.


Forests ◽  
2015 ◽  
Vol 6 (12) ◽  
pp. 1557-1575 ◽  
Author(s):  
Paul Rogers ◽  
Roderick Rogers ◽  
Anne Hedrich ◽  
Patrick Moss

PLoS Genetics ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. e1007220 ◽  
Author(s):  
Mikhail V. Matz ◽  
Eric A. Treml ◽  
Galina V. Aglyamova ◽  
Line K. Bay

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