Recent density decline in wild-collected subarctic crustose coralline algae reveals climate change signature

Geology ◽  
2019 ◽  
Vol 48 (3) ◽  
pp. 226-230 ◽  
Author(s):  
P.T.W. Chan ◽  
J. Halfar ◽  
W.H. Adey ◽  
P.A. Lebednik ◽  
R. Steneck ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Benthic Communities ◽  
Crustose Coralline Alga ◽  
Coralline Algae ◽  
Co2 Uptake ◽  
Strong Correlations ◽  
Crustose Coralline Algae ◽  
Skeletal Density ◽  
Surface Ocean

Abstract Warming surface ocean temperatures combined with the continued diffusion of atmospheric CO2 into seawater have been shown to have detrimental impacts on calcareous marine organisms in tropical and temperate localities. However, greater oceanic CO2 uptake in higher latitudes may present a higher oceanic acidification risk to carbonate organisms residing in Arctic and subarctic habitats. This is especially true for crustose coralline algae that build their skeletons using high-Mg calcite, which is among the least stable and most soluble of the carbonate minerals. Here we present a century-long annually resolved growth, density, and calcification rate record from the crustose coralline alga Clathromorphum nereostratum, a dominant calcifier in Pacific Arctic and subarctic benthic communities. Specimens were collected from the Aleutian Islands, Alaska (USA), a region that has undergone a long-term decline of 0.08 ± 0.01 pH units since the late 19th century. Growth and calcification rates remain relatively stable throughout the record, but skeletal densities have declined substantially since A.D. 1983. Strong correlations to warming sea-surface temperatures indicate that temperature stress may play a significant role in influencing the ability of corallines to calcify. Decreasing algal skeletal density may offset the benefits of continued growth and calcification due to a weakening in structural integrity, which could have detrimental consequences for the diverse reef-like communities associated with algal structures in mid-to-high latitudes.

scholarly journals Bacterial Communities Associated With Healthy and Bleached Crustose Coralline Alga Porolithon onkodes

2021 ◽  
Vol 12 ◽  
Author(s):  
Fangfang Yang ◽  
Zhiliang Xiao ◽  
Zhangliang Wei ◽  
Lijuan Long
Keyword(s):  
Community Structure ◽  
Bacterial Community ◽  
Bacterial Communities ◽  
Larval Settlement ◽  
Crustose Coralline Alga ◽  
Coralline Algae ◽  
Pocillopora Damicornis ◽  
Crustose Coralline Algae ◽  
Settlement And Metamorphosis ◽  
Relative Abundances

Crustose coralline algae (CCA) play vital roles in producing and stabilizing reef structures and inducing the settlement and metamorphosis of invertebrate larvae in coral reef ecosystems. However, little is known about the bacterial communities associated with healthy and bleached CCA and their interactions with coral larval settlement. We collected samples of healthy, middle semi-bleached, and bleached CCA Porolithon onkodes from Sanya Bay in the South China Sea and investigated their influences on the larval settlement and metamorphosis of the reef-building coral Pocillopora damicornis. The larval settlement/metamorphosis rates all exceeded 70% when exposed to healthy, middle semi-bleached, and bleached algae. Furthermore, the compositions of bacterial community using amplicon pyrosequencing of the V3–V4 region of 16S rRNA were investigated. There were no obvious changes in bacterial community structure among healthy, middle semi-bleached, and bleached algae. Alphaproteobacteria, Bacteroidetes, and Gammaproteobacteria were dominant in all samples, which may contribute to coral larval settlement. However, the relative abundances of several bacterial communities varied among groups. The relative abundances of Mesoflavibacter, Ruegeria, Nautella, and Alteromonas in bleached samples were more than double those in the healthy samples, whereas Fodinicurvata and unclassified Rhodobacteraceae were significantly lower in the bleached samples. Additionally, others at the genus level increased significantly from 8.5% in the healthy samples to 22.93% in the bleached samples, which may be related to algal bleaching. These results revealed that the microbial community structure associated with P. onkodes generally displayed a degree of stability. Furthermore, bleached alga was still able to induce larval settlement and metamorphosis.

Low growth resilience of subarctic rhodoliths (Lithothamnion glaciale) to coastal eutrophication

2020 ◽  
Vol 642 ◽  
pp. 117-132 ◽  
Author(s):  
D Bélanger ◽  
P Gagnon
Keyword(s):  
Renewable Resources ◽  
Prolonged Exposure ◽  
Slow Growth ◽  
Cold Water ◽  
Coralline Algae ◽  
Nutrient Concentrations ◽  
Crustose Coralline Algae ◽  
Coastal Marine ◽  
Coastal Marine Ecosystems

Eutrophication is one of the most important drivers of change in coastal marine ecosystems worldwide. Given their slow growth, rhodoliths and the biodiverse communities they support are regarded as non-renewable resources threatened by human activity. Consequences of nutrient enrichment on growth and calcification in crustose coralline algae are equivocal, and even more so in cold-water rhodoliths. We paired a 183 d laboratory mesocosm experiment with a 193 d field experiment on Newfoundland (Canada) rhodoliths (Lithothamnion glaciale) to test the hypothesis that nutrient (nitrate, ammonia, and phosphate) enrichment and biofouling reduce rhodolith growth. Rhodoliths in the laboratory were exposed to 1 of 3 nutrient concentrations (ambient, intermediate, or high) and either of 2 levels of manual cleaning (cleaned or uncleaned) to control biofouling. We exposed rhodoliths in the field to 1 of 2 nutrient concentrations (ambient or elevated). Eutrophication in the laboratory did not affect biofouling; however, manual cleaning reduced biofouling by ~4 times relative to uncleaned rhodoliths. Rhodoliths grew 2 times slower at elevated than ambient nutrient concentrations, and ~27% more in cleaned than uncleaned rhodoliths at all concentrations. Rhodoliths in the field also grew significantly slower under elevated than ambient phosphate concentrations, but only during the first 6 wk, indicating some capacity for long-term recovery. We conclude that despite some growth resilience to low and infrequent increases in nutrient concentrations, subarctic L. glaciale rhodoliths cannot cope with prolonged exposure to modest eutrophication.

scholarly journals Effects of naturally acidified seawater on seagrass calcareous epibionts

2008 ◽  
Vol 4 (6) ◽  
pp. 689-692 ◽  
Author(s):  
Sophie Martin ◽  
Riccardo Rodolfo-Metalpa ◽  
Emma Ransome ◽  
Sonia Rowley ◽  
Maria-Christina Buia ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Total Mass ◽  
Coralline Algae ◽  
Seagrass Habitat ◽  
Seagrass Beds ◽  
Benthic Organisms ◽  
Short Term ◽  
Seawater Acidification ◽  
Surface Ocean

Surface ocean pH is likely to decrease by up to 0.4 units by 2100 due to the uptake of anthropogenic CO 2 from the atmosphere. Short-term experiments have revealed that this degree of seawater acidification can alter calcification rates in certain planktonic and benthic organisms, although the effects recorded may be shock responses and the long-term ecological effects are unknown. Here, we show the response of calcareous seagrass epibionts to elevated CO 2 partial pressure in aquaria and at a volcanic vent area where seagrass habitat has been exposed to high CO 2 levels for decades. Coralline algae were the dominant contributors to calcium carbonate mass on seagrass blades at normal pH but were absent from the system at mean pH 7.7 and were dissolved in aquaria enriched with CO 2 . In the field, bryozoans were the only calcifiers present on seagrass blades at mean pH 7.7 where the total mass of epiphytic calcium carbonate was 90 per cent lower than that at pH 8.2. These findings suggest that ocean acidification may have dramatic effects on the diversity of seagrass habitats and lead to a shift in the biogeochemical cycling of both carbon and carbonate in coastal ecosystems dominated by seagrass beds.

scholarly journals Changes in coral reef communities across a natural gradient in seawater pH

2015 ◽  
Vol 1 (5) ◽  
pp. e1500328 ◽  
Author(s):  
Hannah C. Barkley ◽  
Anne L. Cohen ◽  
Yimnang Golbuu ◽  
Victoria R. Starczak ◽  
Thomas M. DeCarlo ◽  
...  
Keyword(s):  
Coral Reef ◽  
Ocean Acidification ◽  
Benthic Communities ◽  
Coral Community ◽  
Low Ph ◽  
Coralline Algae ◽  
Negative Effects ◽  
Skeletal Density ◽  
Coral Communities ◽  
Coral Reef Ecosystems

Ocean acidification threatens the survival of coral reef ecosystems worldwide. The negative effects of ocean acidification observed in many laboratory experiments have been seen in studies of naturally low-pH reefs, with little evidence to date for adaptation. Recently, we reported initial data suggesting that low-pH coral communities of the Palau Rock Islands appear healthy despite the extreme conditions in which they live. Here, we build on that observation with a comprehensive statistical analysis of benthic communities across Palau’s natural acidification gradient. Our analysis revealed a shift in coral community composition but no impact of acidification on coral richness, coralline algae abundance, macroalgae cover, coral calcification, or skeletal density. However, coral bioerosion increased 11-fold as pH decreased from the barrier reefs to the Rock Island bays. Indeed, a comparison of the naturally low-pH coral reef systems studied so far revealed increased bioerosion to be the only consistent feature among them, as responses varied across other indices of ecosystem health. Our results imply that whereas community responses may vary, escalation of coral reef bioerosion and acceleration of a shift from net accreting to net eroding reef structures will likely be a global signature of ocean acidification.

scholarly journals Intra-Annual Variation in Mesophotic Benthic Assemblages on the Insular Slope of Southwest Puerto Rico as a Function of Depth and Geomorphology

2021 ◽  
Vol 8 ◽  
Author(s):  
Richard S. Appeldoorn ◽  
David L. Ballantine ◽  
Milton Carlo ◽  
Juan J. Cruz Motta ◽  
Michael Nemeth ◽  
...  
Keyword(s):  
Puerto Rico ◽  
Benthic Communities ◽  
Temporal Patterns ◽  
Coralline Algae ◽  
Small Scale ◽  
Percent Cover ◽  
Limited Information ◽  
Crustose Coralline Algae ◽  
Benthic Assemblages ◽  
Disturbance Processes

There is limited information on the intra-annual variability of mesophotic coral ecosystems (MCEs), worldwide. The benthic communities, measured as % cover, of two geomorphologically different mesophotic sites (El Hoyo and Hole-in-the-Wall) were examined during 2009–2010 in southwest Puerto Rico. Depths sampled were 50 and 70 m. At each site/depth combination, two permanent transects, measuring 10-m long by 40-cm wide, were surveyed by successive photoquadrants, 0.24 m2 in area. Scleractinian corals, octocorals, macroalgae, crustose coralline algae (CCA), sponges and unconsolidated sediment were the main components along the transects. Significant community differences were observed both among sites and among depths. Differences among sites were greater at 50 m than at 70 m. The El Hoyo site at 50 m was the most divergent, and this was due to a lower coral and sponge cover and a higher algal cover (Amphiroa spp., Peyssonnelia iridescens, turf) relative to the other site/depth combinations. As a consequence, the differences in community structure with depth were larger at El Hoyo than at Hole-in-the-Wall. The communities at 70 m were distinguished from those at 50 m by the greater proportion of the corals Agaricia undata, Madracis pharensis and CCA, and a reduced cover of the cyanobacterium Schizothrix. Temporal variation in the benthic assemblages was documented throughout the year. For both mesophotic sites, the magnitude of change at 50 m was significantly greater than at 70 m. For both depths, the magnitude of change at El Hoyo was significantly greater than at Hole-in-the-Wall. All assemblages experienced almost the same temporal patterns, despite the differences in species composition across sites and depths. Changes in temporal patterns are driven by an increase in the percent cover of the macroalgae Dictyota spp., and a decrease in the percent cover of non-colonized substrata (sand, pavement or rubble). Relatively rapid, intra-annual changes are dictated by the negative correlation between cyclic Dictyota spp. cover and open substrata cover. Other observed mechanisms for rapid community changes in the photoquadrants were diseases and collapses of substrata along with their associated fauna indicating that small-scale disturbance processes may play an important role within MCEs.

scholarly journals Seasonal shifts in the competitive ability of macroalgae influence the outcomes of coral–algal competition

2020 ◽  
Vol 7 (12) ◽  
pp. 201797
Author(s):  
Kristen T. Brown ◽  
Dorothea Bender-Champ ◽  
Ove Hoegh-Guldberg ◽  
Sophie Dove
Keyword(s):  
Coral Reef ◽  
Competitive Ability ◽  
Benthic Communities ◽  
Coralline Algae ◽  
Crustose Coralline Algae ◽  
Chemical Mechanisms ◽  
Chemical Defences ◽  
Natural Processes ◽  
Coral Reef Ecosystems ◽  
Algal Competition

Understanding the effects of natural processes on coral–algal competition is an important step in identifying the role of macroalgae in perturbed coral reef ecosystems. However, studies investigating coral–algal interactions are often conducted in response to a disturbance, and rarely incorporate seasonal variability. Here, naturally occurring coral–algal interactions were assessed in situ four times a year over 2 years across eight sites spanning diverse benthic communities. In over 6500 recorded coral–algal interactions, cyanobacteria and turf algae were found to be the most damaging regardless of season, resulting in visible damage to coral in greater than 95% of interactions. Macroalgae that primarily compete using chemical mechanisms were found to be more damaging than those that compete using physical mechanisms (e.g. abrasion), with both groups demonstrating decreased competitive ability in summer. While crustose coralline algae were the least damaging to competing coral, during summer, it became three times more competitive. Our results demonstrate that the competitive ability of macroalgae and the outcomes of coral–algal competition can fluctuate in seasonal cycles that may be related to biomass, production of chemical defences and/or physical toughness. The results of this study have important implications for understanding the trajectory and resilience of coral reef ecosystems into the future.

scholarly journals Colonization and growth of crustose coralline algae (Corallinales, Rhodophyta) on the Rocas Atoll

2005 ◽  
Vol 53 (3-4) ◽  
pp. 147-156 ◽  
Author(s):  
Alexandre Bigio Villas Bôas ◽  
Marcia A. de O. Figueiredo ◽  
Roberto Campos Villaça
Keyword(s):  
Growth Rate ◽  
Reef Flat ◽  
Crustose Coralline Alga ◽  
Coralline Algae ◽  
Reef Crest ◽  
Crustose Coralline Algae ◽  
Dark Bottle ◽  
The World ◽  
Cryptic Habitats ◽  
Tidal Pools

Crustose coralline algae play a fundamental role in reef construction all over the world. The aims fo this study were to identify and estimate the abundance of the dominant crustose coralline algae in shallow reef habitats, measuring their colonization, growth rates and productivity. Crusts sampled from different habitats were collected on leeward and windward reefs. Discs made of epoxy putty were fixed on the reef surface to follow coralline colonization and discs containing the dominant coralline algae were fixed on different habitats to measure the crusts' marginal growth. The primary production experiments followed the clear and dark bottle method for dissolved oxygen reading. Porolithon pachydermum was confirmed as the dominant crustose coralline alga on the Rocas Atoll. The non-cryptic flat form of P. pachydermum showed a faster growth rate on the leeward than on the windward reef. This form also had a faster growth rate on the reef crest (0.05 mm.day-1) than on the reef flat (0.01 mm.day-1). The cryptic protuberant form showed a trend, though not significant, towards a faster growth rate on the reef crest and in tidal pools than on the reef flat. Colonization was, in general, very slow as compared to that presented by other reef studies. P. pachydermum was a productive crust both in non-cryptic and cryptic habitats.

Ocean Acidification Reduces Skeletal Density of Hardground‐Forming High‐Latitude Crustose Coralline Algae

2021 ◽  
Vol 48 (5) ◽  
Author(s):  
B. Williams ◽  
P. T. W. Chan ◽  
I. T. Westfield ◽  
D. B. Rasher ◽  
J. Ries
Keyword(s):  
Ocean Acidification ◽  
High Latitude ◽  
Coralline Algae ◽  
Crustose Coralline Algae ◽  
Skeletal Density

scholarly journals Tropical crustose coralline algal individual and community responses to elevated pCO2 under high and low irradiance

2015 ◽  
Vol 73 (3) ◽  
pp. 803-813 ◽  
Author(s):  
Elizabeth Dutra ◽  
Marguerite Koch ◽  
Katherine Peach ◽  
Carrie Manfrino
Keyword(s):  
Benthic Communities ◽  
Co2 Enrichment ◽  
High Irradiance ◽  
Elevated Pco2 ◽  
Coralline Algae ◽  
Algal Community ◽  
Crustose Coralline Algae ◽  
Cayman Island ◽  
Pco2 Treatment ◽  
Diel Cycles

Abstract Crustose coralline algae (CCA) cement reefs and create important habitat and settling sites for reef organisms. The susceptibility of CCA to increasing ocean pCO2 and declining pH or ocean acidification (OA) is a growing concern. Although CCA are autotrophs, there has been little focus on the interaction of elevated pCO2 and irradiance. We examined elevated pCO2 effects on individual CCA and macroalgal benthic communities at high and low irradiance (205–13 µmol photons m−2 s−1) in an aquaria experiment (35 d, June–August 2014) on Little Cayman Island, Caribbean. A dominant Cayman reef wall CCA (Peyssonnelia sp.) in its adult lobed form and individual CCA recruits were used as experimental units. Changes in CCA, fleshy macroalgae (branching and turfs), and microalgae (including microbial biofilm) per cent cover and frequency were examined on macroalgal communities that settled onto plates from the reef. Reef diel cycles of pCO2 and pH were simulated using seawater inflow from a back reef. Although CO2 enrichment to year 2100 levels resulted in 1087 µatm pCO2 in the elevated pCO2 treatment, CaCO3 saturation states remained high (Ωcal ≥ 2.7). Under these conditions, elevated pCO2 had no effect on Peyssonnelia sp. calcification rates or survival regardless of irradiance. Individual CCA surface area on the bottom of settling plates was lower under elevated pCO2, but per cent cover or frequency within the community was unchanged. In contrast, there was a strong and consistent community assemblage response to irradiance. Microalgae increased at high irradiance and CCA increased under low irradiance with no significant pCO2 interaction. Based on this short-term experiment, tropical macroalgal communities are unlikely to shift at pCO2 levels predicted for year 2100 under high or low irradiance. Rather, irradiance and other factors that promote microalgae are likely to be strong drivers of tropical benthic algal community structure under climate change.

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