Seawater carbonate chemistry and net ecosystem calcification and production in a coral community Kaneohe Bay, Oahu, Hawaii, 2011

Net ecosystem calcification rates (NEC) and net photosynthesis (NP) were determined from CO2 seawater parameters on the barrier coral reef of Kaneohe Bay, Oahu, Hawaii. Autosamplers were deployed to collect samples on the barrier reef every 2 hours for six 48-hour deployments, two each in June 2008, August 2009, and January/February 2010. NEC on the Kaneohe Bay barrier reef increased throughout the day and decreased at night. Net calcification continued at low rates at night except for six time periods when net dissolution was measured. The barrier reef was generally net photosynthetic (positive NP) during the day and net respiring (negative NP) at night. NP controlled the diel cycles of the partial pressure of CO2 (pCO2) and aragonite saturation state resulting in high daytime aragonite saturation state levels when calcification rates were at their peak. However, the NEC and NP diel cycles can become decoupled for short periods of time (several hours) without affecting calcification rates. On a net daily basis, net ecosystem production (NEP) of the barrier reef was found to be sometimes net photosynthetic and sometimes net respiring and ranged from -378 to 80 mmol m-2 d-1 when calculated using simple box models. Daily NEC of the barrier reef was positive (net calcification) for all deployments and ranged from 174 to 331 mmol CaCO3 m-2 d-1. Daily NEC was strongly negatively correlated with average daily pCO2 (R2 = 0.76) which ranged from 431 to 622 µatm. Daily NEC of the Kaneohe Bay barrier reef is similar to or higher than daily NEC measured on other coral reefs even though aragonite saturation state levels (mean aragonite saturation state = 2.85) are some of the lowest measured in coral reef ecosystems. It appears that while calcification rate and ?arag are correlated within a single coral reef ecosystem, this relationship does not necessarily hold between different coral reef systems. It can be expected that ocean acidification will not affect coral reefs uniformly and that some may be more sensitive to increasing pCO2 levels than others.

Seawater carbonate chemistry, calcification and dissolution of a coral reef in the northern Red Sea, 2007

In this study we investigated the relations between community calcification of an entire coral reef in the northern Red Sea and annual changes in temperature, aragonite saturation and nutrient loading over a two year period. Summer (April-October) and winter (November-March) average calcification rates varied between 60 ± 20 and 30 ± 20 mmol·m-2·d-1, respectively. In general, calcification increased with temperature and aragonite saturation state of reef water with an apparent effect of nutrients, which is in agreement with most laboratory studies and in situ measurements of single coral growth rates. The calcification rates we measured in the reef correlated remarkably well with precipitation rates of inorganic aragonite calculated for the same temperature and degree of saturation ranges using empirical equations from the literature. This is a very significant finding considering that only a minute portion of reef calcification is inorganic. Hence, these relations could be used to predict the response of coral reefs to ocean acidification and warming.

Seawater carbonate chemistry and community calcification during Reunion Island coral reef community study, 2007

To assess the contribution of soft-bottoms to the carbon cycle in coral reefs, the net community production (p) was measured in winter at 3 stations on La Saline inner reef flat (Reunion Island). Changes in pH and total alkalinity at different irradiances (I) were assessed using benthic chambers (0.2 m2) during a 1-h incubation. Mean grain size, the silt and clay load and chlorophyll a content of the sediments were analysed in each chamber. Daily community production (P), gross community production (Pg) and community respiration (R) were estimated from p-I curves and daily irradiance variations (PAR, 400-700 nm). Sediment characteristics and chlorophyll a contents did not differ between the three sites, except for the silt and clay fraction at one station. R being higher than Pg (84.88 ± 7.36 and -62.29 ± 3.34 mmolC m-2 d-1 respectively), P value reached 22.59 ± 5.66 mmolC m-2 d-1. The sediments were therefore heterotrophic with a mean Pg/R lower than 1 (0.74 ± 0.05) and appear to be a carbon source. Our data suggested the importance of the degradation process in the functioning of near-reef sediments.

Seawater carbonate chemistry and calcification rate during mesocosm experiments with coral Montipora capitata, 2008

A long-term (10 months) controlled experiment was conducted to test the impact of increased partial pressure of carbon dioxide (pCO2) on common calcifying coral reef organisms. The experiment was conducted in replicate continuous flow coral reef mesocosms flushed with unfiltered sea water from Kaneohe Bay, Oahu, Hawaii. Mesocosms were located in full sunlight and experienced diurnal and seasonal fluctuations in temperature and sea water chemistry characteristic of the adjacent reef flat. Treatment mesocosms were manipulated to simulate an increase in pCO2 to levels expected in this century [midday pCO2 levels exceeding control mesocosms by 365 ± 130 µatm (mean ± sd)]. Acidification had a profound impact on the development and growth of crustose coralline algae (CCA) populations. During the experiment, CCA developed 25% cover in the control mesocosms and only 4% in the acidified mesocosms, representing an 86% relative reduction. Free-living associations of CCA known as rhodoliths living in the control mesocosms grew at a rate of 0.6 g buoyant weight per year while those in the acidified experimental treatment decreased in weight at a rate of 0.9 g buoyant weight per year, representing a 250% difference. CCA play an important role in the growth and stabilization of carbonate reefs, so future changes of this magnitude could greatly impact coral reefs throughout the world. Coral calcification decreased between 15% and 20% under acidified conditions. Linear extension decreased by 14% under acidified conditions in one experiment. Larvae of the coral Pocillopora damicornis were able to recruit under the acidified conditions. In addition, there was no significant difference in production of gametes by the coral Montipora capitata after 6 months of exposure to the treatments.

Cape Lookout cold-water coral area, coral ages and environmental parameters for the last glacial cycle

Climatic and oceanographic changes, as occurring at a glacial-interglacial scale, may alter the environmental conditions needed for the development of prolific cold-water coral reefs and mounds. Studies constraining the temporal distribution of cold-water corals in the NE Atlantic suggested the cyclic changes of the Atlantic Meridional Overturning Circulation as the main driver for the development and dispersal of cold-water coral ecosystems. However, conclusions were hindered by lack of data from the NW Atlantic. Aiming to overcome this lack of data, the temporal occurrence of cold-water corals in the Cape Lookout area along the southeastern US margin was explored by U-series dating. Furthermore, the local influence of the regional water masses, namely the Gulf Stream, on cold-water coral proliferation and occurrence since the Last Glacial Maximum was examined. Results suggest that the occurrence of cold-water corals in the Cape Lookout area is restricted to interglacial periods, with corals being present during the last ~7 kyr and also during the Eemian (~125 ka). The reconstructed local environmental conditions suggest an offshore displacement of the Gulf Stream and increased influence from the Mid-Atlantic Bight shelf waters during the last glacial period. During the deglacial sea level rise, the Gulf Stream moved coastward providing present-day-like conditions to the surface waters. Nevertheless, present-day conditions at the ocean sea floor were not established before 7.5 cal ka BP once the ultimate demise of the Laurentide ice-sheet caused the final sea level rise and the displacement of the Gulf Stream to its present location. Occasional presence of the Gulf Stream over the site during the Mid- to Late Holocene coincides with enhanced bottom current strength and a slightly higher bottom water temperature, which are environmental conditions that are favorable for cold-water coral growth.

Annotated record of the detailed examination of Mn deposits on the coral banks of the continental shelf in the south-western coastal area of the Gulf of Mexico off Texas

During U.S. Department of Interior, Bureau of Land Management (BLM) public hearings held in 1973, 1974 and 1975 prior to Texas Outer Continental Shelf (OCS) oil and gas lease sales, concern was expressed by the National Marine Fisheries Service, scientists from Texas A&M and the University of Texas and private citizens over the possible environmental impact of oil and gas drilling and production operations on coral reefs and fishing banks in or adjacent to lease blocks to be sold. As a result, certain restrictive regulations concerning drilling operations in the vicinity of the well documented coral reefs and biostromal communities at the East and West Flower Gardens were established by BLM, and Signal Oil Company was required to provide a biological and geological baseline study of the less well known Stetson Bank before a drilling permit could be issued. Considering the almost total lack of knowledge of the geology and biotic communities associated with the South Texas OCS banks lying in or near lease blocks to be offered for sale in 1975, BLM contracted with Texas A&M University to provide the biological and geological baseline information required to facilitate judgments as to the extent and nature of restrictive regulations on drilling near these banks which might be required to insure their protection. In pursuit of this, scientists from Texas A&M University were to direct their attention toward assessments of ground fish populations, unique biological and geological features, substratum type and distribution, and the biotic and geologic relationships between these banks and those farther north.

Seawater carbonate chemistry and calcification during an experiment with a coral Porites lutea, 2004

Using living corals collected from Okinawan coral reefs, laboratory experiments were performed to investigate the relationship between coral calcification and aragonite saturation state (W) of seawater at 25?C. Calcification rate of a massive coral Porites lutea cultured in a beaker showed a linear increase with increasing Waragonite values (1.08-7.77) of seawater. The increasing trend of calcification rate (c) for W is expressed as an equation, c = aW + b (a, b: constants). When W was larger than ~4, the coral samples calcified during nighttime, indicating an evidence of dark calcification. This study strongly suggests that calcification of Porites lutea depends on W of ambient seawater. A decrease in saturation state of seawater due to increased pCO2 may decrease reef-building capacity of corals through reducing calcification rate of corals.

Mediterranean cold-water coral measurements

This study presents aggradation rates supplemented for the first time by carbonate accumulation rates from Mediterranean cold-water coral sites considering three different regional and geomorphological settings: (i) a cold-water coral ridge (eastern Melilla coral province, Alboran Sea), (ii) a cold-water coral rubble talus deposit at the base of a submarine cliff (Urania Bank, Strait of Sicily) and (iii) a cold-water coral deposit rooted on a predefined topographic high overgrown by cold-water corals (Santa Maria di Leuca coral province, Ionian Sea). The mean aggradation rates of the respective cold-water coral deposits vary between 10 and 530 cm kyr?1 and the mean carbonate accumulation rates range between 8 and 396 g cm?2 kyr?1 with a maximum of 503 g cm?2 kyr?1 reached in the eastern Melilla coral province. Compared to other deep-water depositional environments the Mediterranean cold-water coral sites reveal significantly higher carbonate accumulation rates that were even in the range of the highest productive shallow-water Mediterranean carbonate factories (e.g. Cladocora caespitosa coral reefs). Focusing exclusively on cold-water coral occurrences, the carbonate accumulation rates of the Mediterranean cold-water coral sites are in the lower range of those obtained for the prolific Norwegian coral occurrences, but exhibit much higher rates than the cold-water coral mounds off Ireland. This study clearly indicates that cold-water corals have the potential to act as important carbonate factories and regional carbonate sinks within the Mediterranean Sea. Moreover, the data highlight the potential of cold-water corals to store carbonate with rates in the range of tropical shallow-water reefs. In order to evaluate the contribution of the cold-water coral carbonate factory to the regional or global carbonate/carbon cycle, an improved understanding of the temporal and spatial variability in aggradation and carbonate accumulation rates and areal estimates of the respective regions is needed.

Changes in microbial diversity associated with two coral species recovering from a stressed state in a public aquarium system:Microbial diversity associated with aquarium corals

Coral diseases are a major factor in the decline of coral reefs worldwide, and a large proportion of studies focusing on disease causation use aquaria to control variables that affect disease occurrence and development. Public aquaria can therefore provide an invaluable resource to study the factors contributing to health and disease. In November 2010 the corals within the main display tank at the Horniman Museum and Gardens, London, UK, underwent a severe stress event due to reduced water quality, which resulted in death of a large number of coral colonies. Three separate colonies of two species of reef coral, Seritopora hystrix and Montipora capricornis showing signs of stress and acute tissue loss were removed from the display tank and placed in a research tank with improved water quality. Both coral species showed a significant difference in 16S rRNA gene bacterial diversity between healthy and stressed states (S. hystrix; ANOSIM, R=0.44, p=0.02 and M. capricornis; ANOSIM, R=0.33, p=0.01), and between the stressed state and the recovering corals. After four months the bacterial communities had returned to a similar state to that seen in healthy corals of the same species. The bacterial communities associated with the two coral species were distinct, despite them
being reared under identical environmental conditions. Despite the environmental perturbation being identical different visual signs were seen in each species and distinctly different bacterial communities associated with the stressed state occurred within them. Recovery of the visually healthy state was associated with a return of the bacterial community, within two months, to the pre-disturbance state. These observations suggest that coral-associated microbial communities are remarkably resilient and return to a very similar stable state following disturbance.

Implementación de un detector de coral utilizando filtros Gabor Wavelets y máquinas de aprendizaje

Este trabajo se enfoca en la implementación de un detector de arrecife de coral de desempeño rápido que se utiliza para un vehículo autónomo submarino (Autonomous Underwater Vehicle, AUV, por sus siglas en inglés). Una detección rápida de la presencia de coral asegura la estabilización del AUV frente al arrecife en el menor tiempo posible, evitando colisiones con el coral. La detección de coral se hace en una imagen que captura la escena que percibe la cámara del AUV. Se realiza una clasificación píxel por píxel entre dos clases: arrecife de coral y el plano de fondo que no es coral. A cada píxel de la imagen se le asigna un vector característico, el mismo que se genera mediante el uso de filtros Gabor Wavelets. Éstos son implementados en C++ y la librería OpenCV. Los vectores característicos son clasificados a través de nueve algoritmos de máquinas de aprendizaje. El desempeño de cada algoritmo se compara mediante la precisión y el tiempo de ejecución. El algoritmo de Árboles de Decisión resultó ser el más rápido y preciso de entre todos los algoritmos. Se creó una base de datos de 621 imágenes de corales de Belice (110 imágenes de entrenamiento y 511 imágenes de prueba).

International workshop on "Different survey methods for coral reef fish, including methods based on underwater video"

In September 2013, staff from the University of the South Pacific (USP) Honiara campus, the Secretariat of the Pacific Community (SPC) and IFREMER (UR LEADNC, AMBIO project) in New Caledonia, and the French Institute for Pacific Coral Reefs (IRCP) in Moorea, French Polynesia, co-facilitated a workshop entitled “Different survey methods of coral reef fish, including the methods based on underwater video”. The workshop was attended by students from USP, NGO and fisheries officers. They were trained to several underwater visual census techniques and to the STAVIRO video-based technique, including both field work and data analysis.

Investigating Stakeholders’ Preferences for Coral Reef Research Funding in Florida

Abstract: Heavily used and highly valuable, the Florida Reef is one of the world's most threatened ecosystems. Stakeholders from a densely urbanized coastal region in proximity to the reef system recognize its degradation, but their comprehension of climate change and commitment to pay for sustainable management and research funding have been opaque. With an emphasis on recreational anglers, residential stakeholders were surveyed online about their marine activities, perceptions of resources and threats, and willingness to pay (WTP) for dedicated coral reef research funding in Florida. The majority of stakeholders are wealthy, well educated, and politically independent. Supermajorities favored the two scenarios of taxation for a Florida Coral Reef Research Fund, and the scenario with matching federal funds earned higher support. In regression analyses, several factors emerged as significant contributors to stakeholders’ preferences, and the four recurring factors in extended models were prioritizing the environment over the economy, donating to environmental causes, concern about coral reefs, and concern about climate change, with the latter indicating a recent shift of opinion. Status in terms of income and education were found insignificant, and surprisingly income was negatively correlated with WTP. Perceptions through lenses of environmental and emotional attachments appear to overwhelm conventional status-based factors. Applied statewide, the first scenario's extrapolated WTP (based on a sales tax rate of 2.9%) would generate $675 million annually, and the extrapolated WTP under the second scenario, with matching federal funds (based on a sales tax rate of 3.0%) would generate $1.4 billion. Keywords: willingness to pay, coral reef research, taxation, climate change, stakeholder, perceptions, Florida Reef, recreational fishing, anglers

Herbivores strongly influence algal recruitment in both coral- and algal-dominated coral reef habitats

Coral reefs can exist as coral- and macroalgae-dominated habitats often separated by only a few hundred metres. While herbivorous fish are known to depress the abundance of algae and help maintain the function of coral-dominated habitats, less is known about their influence in algae-dominated habitats. Here, we quantified herbivorous fish and benthic algal communities over a 6 mo period in coral-dominated (back-reef) and algal-dominated (lagoon) habitats in a relatively undisturbed fringing coral reef (Ningaloo, Western Australia). Simulta - neously, we tested the effects of herbivorous fish on algal recruitment in both habitats using recruitment tiles and fish exclusion cages. The composition of established algal communities differed consistently between habitats, with the back-reef hosting a more diverse community than the Sargassum-dominated lagoon. However, total algal biomass and cover only differed between habitats in autumn, coinciding with maximum Sargassum biomass. The back-reef hosted high coral cover and a diverse herbivorous fish community, with herbivore biomass an order of magnitude greater than the lagoon. Despite these differences in herbivore composition, exclusion of large herbivores had a similar positive effect to foliose macroalgae recruitment on experimental tiles in both back-reef and lagoon habitats. Additionally, territorial damselfish found in the backreef increased turf algae cover and decreased crustose coralline algae cover on recruitment tiles. Collectively, our results show that disparate herbivorous fish communities in coral- and algaedominated habitats are similarly able to limit the recruitment of foliose macroalgae, but suggest that when herbivorous fish biomass and diversity are relatively low, macroalgal communities are able to escape herbivore control through increased growth.

Data collection, storage and retrieval with an underwater sensor network

In this paper we present a novel platform for underwater sensor networks to be used for long-term monitoring of coral reefs and �sheries. The sensor network consists of static and mobile underwater sensor nodes. The nodes communicate point-to-point using a novel high-speed optical communication system integrated into the TinyOS stack, and they broadcast using an acoustic protocol integrated in the TinyOS stack. The nodes have a variety of sensing capabilities, including cameras, water temperature, and pressure. The mobile nodes can locate and hover above the static nodes for data muling, and they can perform network maintenance functions such as deployment, relocation, and recovery. In this paper we describe the hardware and software architecture of this underwater sensor network. We then describe the optical and acoustic networking protocols and present experimental networking and data collected in a pool, in rivers, and in the ocean. Finally, we describe our experiments with mobility for data muling in this network.

Flower animals

The coral reefs around the world may be likened to canaries down the mineshaft of global warming. These sensitive plant-like animals have evolved for life in tropical seas. Their needs are quite specific – not too cold, not too hot. A rise of as little as one degree Celsius is enough to cause some bleaching of these colourful jewels of the sea. Many climate models indicate we can expect sea temperature increases of between two and six degrees Celsius. Research - such as that detailed in a 2004 report by the University of Queensland’s Centre for Marine Studies – indicates that by the year 2050 most of the worlds major reef systems will be dead. Many of us have heard this kind of information, but it remains difficult to comprehend. It’s almost impossible to imagine the death of the Great Barrier Reef. Some six to nine thousand years old and visible from space, it is the world’s largest structure created by living organisms. Yet whilst it is hard to believe, this gentle, sensitive giant is at grave risk because it cannot adapt quickly enough to the changes in the environment. This cluster of fluffy felt brain coral sculptures are connected in real time to temperature data collected by monitoring stations within the Great Barrier Reef, that form part of the Australian Institute of Marine Science’s Great Barrier Reed Ocean Observing System. These corals display illumination patterns showing changes in sea temperature at Heron Reef, one of the 2,900 reefs that comprise the Great Barrier Reef. Their spectrum of colour ranges from cool hues, through warm tones to bright white when temperatures exceed those that tropical corals are able to tolerate over sustained periods. The Flower Animals also blush in colour and make sound when people come within close proximity. In a reef, fishes and other creatures generate significant amounts of sound. These cacophonies are considered an indicator of reef health, and are used by reef fish to determine where they can best live and forage.