Effects of the herbicide diuron on the early life history stages of coral

The effects of the herbicide diuron on the early life history stages of broadcast spawning and brooding corals were examined in laboratory experiments. Fertilisation of Acropora millepora and Montipora aequituberculata oocytes were not inhibited at diuron concentrations of up to 1000 mu gl(-1). Metamorphosis of symbiont-free A. millepora larvae was only significantly inhibited at 300 mu gl(-1) diuron. Pocillopora damicornis larvae, which contain symbiotic dinoflagellates, were able to undergo metamorphosis after 24h exposure to diuron at 1000 mu gl(-1). Two-week old P. damicornis recruits on the other hand were as susceptible to diuron as adult colonies, with expulsion of symbiotic dinoflagellates (bleaching) evident at 10 mu gl(-1) diuron after 96 h exposure. Reversible metamorphosis was observed at high diuron concentrations, with fully bleached polyps escaping from their skeletons. Pulse amplitude modulation (PAM) chlorophyll fluorescence techniques demonstrated a reduction in photosynthetic efficiency (Delta F/F'(m)) in illuminated P. dami- cornis recruits after a 2h exposure to 1 mu gl(-1) diuron. The dark-adapted quantum yields (F-v/F-m also declined, indicating chronic photoinhibition and damage to photosystem H. Crown Copyright (c) 2004 Published by Elsevier Ltd. All rights reserved.

Enhanced energy status of corals on coastal, high-turbidity reefs

Sedimentation and high turbidity have long been considered a major threat to corals, causing world-wide concern for the health of coral reefs in coastal environments. While studies have demonstrated that sediment conditions characteristic of inshore reefs cause stress in corals, the consequences of such conditions for the physiological status of corals require testing in field situations. Here, I compare the size of energy stores (as lipid content), a proxy for physiological condition, of 2 coral species (Turbinaria mesenterina and Acropora valida) between coastal and offshore environments. Corals on coastal reefs contained 4-fold (T mesenterina) and 2-fold (A. valida) more lipid than conspecifics offshore, despite 1 order of magnitude higher turbidity levels inshore. Results were consistent across 4 sites in each environment. Reproductive investment in A. valida (a seasonal mass spawner) did not vary between environments, suggesting that the larger lipid stores in corals on coastal reefs are mainly somatic energy reserves. These results demonstrate that the environmental conditions on inshore, high-turbidity reefs do not always impact negatively on the physiology of corals. The contrasting lipid levels of T. mesenterina between environments may explain its greater success on coastal reefs.

Genetic structure of a reef-building coral from thermally distinct environments on the Great Barrier Reef

Adaptation to localised thermal regimes is facilitated by restricted gene flow, ultimately leading to genetic divergence among populations and differences in their physiological tolerances. Allozyme analysis of six polymorphic loci was used to assess genetic differentiation between nine populations of the reef-building coral Acropora millepora over a latitudinal temperature gradient on the inshore regions of the Great Barrier Reef (GBR). Small but significant genetic differentiation indicative of moderate levels of gene flow (pairwise F-ST 0.023 to 0.077) was found between southern populations of A. millepora in cooler regions of the GBR and the warmer, central or northern GBR populations. Patterns of genetic differentiation at these putatively neutral allozyme loci broadly matched experimental variation in thermal tolerance and were consistent with local thermal regimes (warmest monthly-averages) for the A. millepora populations examined. It is therefore hypothesized that natural selection has influenced the thermal tolerance of the A. millepora populations examined and greater genetic divergence is likely to be revealed by examination of genetic markers under the direct effects of natural selection.

Viruses: agents of coral disease?

The potential role of viruses in coral disease has only recently begun to receive attention. Here we describe our attempts to determine whether viruses are present in thermally stressed corals Pavona danai, Acropora formosa and Stylophora pistillata and zoanthids Zoanthus sp., and their zooxanthellae. Heat-shocked P. danai, A. formosa and Zoanthus sp. all produced numerous virus-like particles (VLPs) that were evident in the animal tissue, zooxanthellae and the surrounding seawater; VLPs were also seen around heat-shocked freshly isolated zooxanthellae (FIZ) from P. danai and S. pistillata. The most commonly seen VLPs were tail-less, hexagonal and about 40 to 50 nm in diameter, though a diverse range of other VLP morphotypes (e.g. rounded, rod-shaped, droplet-shaped, filamentous) were also present around corals. When VLPs around heat-shocked FIZ from S. pistillata were added to non-stressed FIZ from this coral, they resulted in cell lysis, suggesting that an infectious agent was present; however, analysis with transmission electron microscopy provided no clear evidence of viral infection. The release of diverse VLPs was again apparent when flow cytometry was used to enumerate release by heat-stressed A. formosa nubbins. Our data support the infection of reef corals by viruses, though we cannot yet determine the precise origin (i.e. coral, zooxanthellae and/or surface microbes) of the VLPs seen. Furthermore, genome sequence data are required to establish the presence of viruses unequivocally.

Data compilation on the biological response to ocean acidification: environmental and experimental context of data sets and related literature

The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.

Preferência e competição alimentar em um grupo de Sapajus flavius em fragmento de Mata Atlântica em Caaporã – Paraíba – Brasil

Feeding is the primary selective pressure in all forms of animals. Nutritional ecological models predict consequences of preferred and non-preferred food consumption on behavioural, physiological and morphological adaptations. At same time, socioecological models infer socio-organizarion patterns based on feeding competition faced by animals. A list of preferred foods, and inferences regarding the intensity of feeding competition and its behavioural consequences are information of much importance for management of populations in fragments. In this work we observed the feeding behavior and spatial positioning of a group of more than 100 blond capuchin monkeys (Sapajus flavius) that inhabit a fragment of Atlantic forest, surrounded by sugarcane plantation. We compared the consumption of different food items with their monthly availability in the area to define the preferred and fallback food items. We recorded the vocalizations of aggression and the inter-individual distance (area of Minimum Convex Polygon/n individuals) to infer the type of food competition experienced by animals. In the year studied the fruit feeding time correlated with top consumed fruit productivity, indicating preference for fruits. Our data indicate that the species Elaeis sp., Cecropia palmata, Inga spp. and Simarouba amara are the preferred food items in the diet. Available all year round and uniformly distributed, sugarcane was a regular item in the diet and its was characterized as a staple fallback food for this group. Although fruits are preferential food items, direct competition rate did not correlate to fruit productivity in the area, maintaining the high rates throughout the year (2.45 events/ hour). The inter-individual distance index positively correlated with rain fall indicating scramble food competition. The number of neighbours of females carrying infants was smaller when fruit productivity is low, indicating that females carrying infants are suffering increased indirect competition. Our data indicates that blond capuchins in this fragment make use of sugar cane as a staple fallback food, which evidence the importance of sugar cane landscape for the survival of this critically endangered capuchin species in fragmented habitats in Northeast Brazil. A preliminary list of preferred and important foods is offered, and can assist in the choice of trees for reforestation, better fragments to be preserved and areas of release and translocation of animals. We did not observe an increase of contest competition while using preferred foods, but when using staple FBF. This may be due the altered environment, which results in high competition food throughout the year. Both the food preference as the social and behavioral consequences of high food competition experienced by animals in this fragment must be accompanied over the years to ensure the survival of this population.

Preferência e competição alimentar em um grupo de Sapajus flavius em fragmento de Mata Atlântica em Caaporã – Paraíba – Brasil

Feeding is the primary selective pressure in all forms of animals. Nutritional ecological models predict consequences of preferred and non-preferred food consumption on behavioural, physiological and morphological adaptations. At same time, socioecological models infer socio-organizarion patterns based on feeding competition faced by animals. A list of preferred foods, and inferences regarding the intensity of feeding competition and its behavioural consequences are information of much importance for management of populations in fragments. In this work we observed the feeding behavior and spatial positioning of a group of more than 100 blond capuchin monkeys (Sapajus flavius) that inhabit a fragment of Atlantic forest, surrounded by sugarcane plantation. We compared the consumption of different food items with their monthly availability in the area to define the preferred and fallback food items. We recorded the vocalizations of aggression and the inter-individual distance (area of Minimum Convex Polygon/n individuals) to infer the type of food competition experienced by animals. In the year studied the fruit feeding time correlated with top consumed fruit productivity, indicating preference for fruits. Our data indicate that the species Elaeis sp., Cecropia palmata, Inga spp. and Simarouba amara are the preferred food items in the diet. Available all year round and uniformly distributed, sugarcane was a regular item in the diet and its was characterized as a staple fallback food for this group. Although fruits are preferential food items, direct competition rate did not correlate to fruit productivity in the area, maintaining the high rates throughout the year (2.45 events/ hour). The inter-individual distance index positively correlated with rain fall indicating scramble food competition. The number of neighbours of females carrying infants was smaller when fruit productivity is low, indicating that females carrying infants are suffering increased indirect competition. Our data indicates that blond capuchins in this fragment make use of sugar cane as a staple fallback food, which evidence the importance of sugar cane landscape for the survival of this critically endangered capuchin species in fragmented habitats in Northeast Brazil. A preliminary list of preferred and important foods is offered, and can assist in the choice of trees for reforestation, better fragments to be preserved and areas of release and translocation of animals. We did not observe an increase of contest competition while using preferred foods, but when using staple FBF. This may be due the altered environment, which results in high competition food throughout the year. Both the food preference as the social and behavioral consequences of high food competition experienced by animals in this fragment must be accompanied over the years to ensure the survival of this population.

R-codes, and coral abundance, water temperature and transect characteristics of nearshore reefs in Belize

Coral reefs are increasingly threatened by global and local anthropogenic stressors, such as rising seawater temperature and nutrient enrichment. These two stressors vary widely across the reef face and parsing out their influence on coral communities at reef system scales has been particularly challenging. Here, we investigate the influence of temperature and nutrients on coral community traits and life history strategies on lagoonal reefs across the Belize Mesoamerican Barrier Reef System (MBRS). A novel metric was developed using ultra-high-resolution sea surface temperatures (SST) to classify reefs as enduring low (lowTP), moderate (modTP), or extreme (extTP) temperature parameters over 10 years (2003 to 2012). Chlorophyll-a (chl a) records obtained for the same interval were employed as a proxy for bulk nutrients and these records were complemented with in situ measurements to "sea truth" nutrient content across the three reef types. Chl a concentrations were highest at extTP sites, medial at modTP sites and lowest at lowTP sites. Coral species richness, abundance, diversity, density, and percent cover were lower at extTP sites compared to lowTP and modTP sites, but these reef community traits did not differ between lowTP and modTP sites. Coral life history strategy analyses showed that extTP sites were dominated by hardy stress-tolerant and fast-growing weedy coral species, while lowTP and modTP sites consisted of competitive, generalist, weedy, and stress-tolerant coral species. These results suggest that differences in coral community traits and life history strategies between extTP and lowTP/modTP sites were driven primarily by temperature differences with differences in nutrients across site types playing a lesser role. Dominance of weedy and stress-tolerant genera at extTP sites suggests that corals utilizing these two life history strategies may be better suited to cope with warmer oceans and thus may warrant further protective status during this climate change interval. Data associated with this project are archived here, including: -SST data -Satellite Chl a data -Nutrient measurements -Raw coral community survey data For questions contact Justin Baumann (j.baumann3 gmail.com)

Coral energy reserves and calcification in a high-CO2 world at two temperatures

Rising atmospheric CO2 concentrations threaten coral reefs globally by causing ocean acidification (OA) and warming. Yet, the combined effects of elevated pCO2 and temperature on coral physiology and resilience remain poorly understood. While coral calcification and energy reserves are important health indicators, no studies to date have measured energy reserve pools (i.e., lipid, protein, and carbohydrate) together with calcification under OA conditions under different temperature scenarios. Four coral species, Acropora millepora, Montipora monasteriata, Pocillopora damicornis, Turbinaria reniformis, were reared under a total of six conditions for 3.5 weeks, representing three pCO2 levels (382, 607, 741 µatm), and two temperature regimes (26.5, 29.0°C) within each pCO2 level. After one month under experimental conditions, only A. millepora decreased calcification (-53%) in response to seawater pCO2 expected by the end of this century, whereas the other three species maintained calcification rates even when both pCO2 and temperature were elevated. Coral energy reserves showed mixed responses to elevated pCO2 and temperature, and were either unaffected or displayed nonlinear responses with both the lowest and highest concentrations often observed at the mid-pCO2 level of 607 µatm. Biweekly feeding may have helped corals maintain calcification rates and energy reserves under these conditions. Temperature often modulated the response of many aspects of coral physiology to OA, and both mitigated and worsened pCO2 effects. This demonstrates for the first time that coral energy reserves are generally not metabolized to sustain calcification under OA, which has important implications for coral health and bleaching resilience in a high-CO2 world. Overall, these findings suggest that some corals could be more resistant to simultaneously warming and acidifying oceans than previously expected.

Seawater carbonate chemistry and processes during experiments with a coral community, 2008

Ocean acidification represents a key threat to coral reefs by reducing the calcification rate of framework builders. In addition, acidification is likely to affect the relationship between corals and their symbiotic dinoflagellates and the productivity of this association. However, little is known about how acidification impacts on the physiology of reef builders and how acidification interacts with warming. Here, we report on an 8-week study that compared bleaching, productivity, and calcification responses of crustose coralline algae (CCA) and branching (Acropora) and massive (Porites) coral species in response to acidification and warming. Using a 30-tank experimental system, we manipulated CO2 levels to simulate doubling and three- to fourfold increases [Intergovernmental Panel on Climate Change (IPCC) projection categories IV and VI] relative to present-day levels under cool and warm scenarios. Results indicated that high CO2 is a bleaching agent for corals and CCA under high irradiance, acting synergistically with warming to lower thermal bleaching thresholds. We propose that CO2 induces bleaching via its impact on photoprotective mechanisms of the photosystems. Overall, acidification impacted more strongly on bleaching and productivity than on calcification. Interestingly, the intermediate, warm CO2 scenario led to a 30% increase in productivity in Acropora, whereas high CO2 lead to zero productivity in both corals. CCA were most sensitive to acidification, with high CO2 leading to negative productivity and high rates of net dissolution. Our findings suggest that sensitive reef-building species such as CCA may be pushed beyond their thresholds for growth and survival within the next few decades whereas corals will show delayed and mixed responses.

Seawater carbonate chemistry and settlement of a spawning coral on three common species of crustose coralline algae

Concern about the impacts of ocean acidification (OA) on ecosystem function has prompted many studies to focus on larval recruitment, demonstrating declines in settlement and early growth at elevated CO2 concentrations. Since larval settlement is often driven by particular cues governed by crustose coralline algae (CCA), it is important to determine whether OA reduces larval recruitment with specific CCA and the generality of any effects. We tested the effect of elevated CO2 on the survival and settlement of larvae from the common spawning coral Acropora selago with 3 ecologically important species of CCA, Porolithon onkodes, Sporolithon sp., and Titanoderma sp. After 3 d in no-choice laboratory assays at 447, 705, and 1214 µatm pCO2, the rates of coral settlement declined as pCO2 increased with all CCA taxa. The magnitude of the effect was highest with Titanoderma sp., decreasing by 87% from the ambient to highest CO2 treatment. In general, there were high rates of larval mortality, which were greater with the P. onkodes and Sporolithon sp. treatments (~80%) compared to the Titanoderma sp. treatment (65%). There was an increase in larval mortality as pCO2 increased, but this was variable among the CCA species. It appears that OA reduces coral settlement by rapidly altering the chemical cues associated with the CCA thalli and microbial community, and potentially by directly affecting larval viability.

Presence of competitors influences photosynthesis, but not growth, of the hard coral Porites cylindrica at elevated seawater CO2

Changes in environmental conditions, such as those caused by elevated carbon dioxide (CO2), potentially alter the outcome of competitive interactions between species. This study aimed to understand how elevated CO2 could influence competitive interactions between hard and soft corals, by investigating growth and photosynthetic activity of Porites cylindrica (a hard coral) under elevated CO2 and in the presence of another hard coral and two soft coral competitors. Corals were collected from reefs around Orpheus and Pelorus Islands on the Great Barrier Reef, Australia. They were then exposed to elevated pCO2 for 4 weeks with two CO2 treatments: intermediate (pCO2 648) and high (pCO2 1003) compared with a control (unmanipulated seawater) treatment (pCO2 358). Porites cylindrica growth did not vary among pCO2 treatments, regardless of the presence and type of competitors, nor was the growth of another hard coral species, Acropora cerealis, affected by pCO2 treatment. Photosynthetic rates of P. cylindrica were sensitive to variations in pCO2, and varied between the side of the fragment facing the competitors vs. the side facing away from the competitor. However, variation in photosynthetic rates depended on pCO2 treatment, competitor identity, and whether the photosynthetic yields were measured as maximum or effective photosynthetic yield. This study suggests that elevated CO2 may impair photosynthetic activity, but not growth, of a hard coral under competition and confirms the hypothesis that soft corals are generally resistant to elevated CO2. Overall, our results indicate that shifts in the species composition in coral communities as a result of elevated CO2 could be more strongly related to the individual tolerance of different species rather than a result of competitive interactions between species.

Seawater carbonate chemistry and calcification rate of colonies of Stylophora pistillata, 1998

The carbonate chemistry of seawater is usually not considered to be an important factor influencing calcium-carbonate-precipitation by corals because surface seawater is supersaturated with respect to aragonite. Recent reports, however, suggest that it could play a major role in the evolution and biogeography of recent corals. We investigated the calcification rates of five colonies of the zooxanthellate coral Stylophora pistillata in synthetic seawater using the alkalinity anomaly technique. Changes in aragonite saturation from 98% to 585% were obtained by manipulating the calcium concentration. The results show a nonlinear increase in calcification rate as a function of aragonite saturation level. Calcification increases nearly 3-fold when aragonite saturation increases from 98% to 390%, i.e., close to the typical present saturation state of tropical seawater. There is no further increase of calcification at saturation values above this threshold. Preliminary data suggest that another coral species, Acropora sp., displays a similar behaviour. These experimental results suggest: (1) that the rate of calcification does not change significantly within the range of saturation levels corresponding to the last glacial-interglacial cycle, and (2) that it may decrease significantly in the future as a result of the decrease in the saturation level due to anthropogenic release of CO2 into the atmosphere. Experimental studies that control environmental conditions and seawater composition provide unique opportunities to unravel the response of corals to global environmental changes.

Seawater carbonate chemistry and calcification during experiments with corals, 2003

Biogenic calcification is influenced by the concentration of available carbonate ions. The recent confirmation of this for hermatypic corals has raised concern over the future of coral reefs because [CO3] is a decreasing function of increasing pCO2 in the atmosphere. As one of the overriding features of coral reefs is their diversity, understanding the degree of variability between species in their ability to cope with a change in [CO3] is a priority. We cultured four phylogenetically and physiologically different species of hermatypic coral (Acropora verweyi, Galaxea fascicularis, Pavona cactus and Turbinaria reniformis) under 'normal' (280 µmol/kg) and 'low' (140 µmol/kg) carbonate-ion concentrations. The effect on skeletogenesis was investigated quantitatively (by calcification rate) and qualitatively (by microstructural appearance of growing crystalline fibres using scanning electron microscopy (SEM)). The 'low carbonate' treatment resulted in a significant suppression of calcification rate and a tendency for weaker crystallization at the distal tips of fibres. However, while the calcification rate was affected uniformly across species (13-18% reduction), the magnitude of the microstructural response was highly species specific: crystallization was most markedly affected in A. verweyi and least in T. reniformis. These results are discussed in relation to past records and future predictions of carbonate variability in the oceans.