Reef Stations Research Articles

Species composition and distribution of mollusca on dead coral from Central to North Vietnam

A study on Mollusks’ species composition and distribution on dead coral from Quang Ngai to Cat Ba was conducted during the field survey between Vietnam and Russia on the AKADEMIC OPARIN RC vessel in 2021 at 39 reef stations in 14 study areas. By comparative morphology method, the authors have identified 135 taxa of Mollusca belonging to 48 families, 4 classes on coral reefs. The species composition of Mollusca was slightly different between study areas.

Dynamics of the Benthic Communities of Pigeon Islets (Guadeloupe Island, Lesser Antilles) from 2012 to 2021 Monitored by a Photo-Quadrats Technique

Since 2012, the benthic communities of the Pigeon Islets (Guadeloupe Island, Lesser Antilles) have been monitored biannually by the National Park of Guadeloupe using photo—quadrats. This monitoring was carried out at 12 coral reef stations distributed around the islets. The data collected from 2012 to 2021 highlight the significant events that disrupted the coral communities of Guadeloupe. Among these remarkable phenomena, an episode of coral bleaching occurred in 2019, followed by the appearance of a new coral disease, Stony Coral Tissue Loss Disease (SCTLD), in 2020. As a result of these threats, a drop of 54% of coral cover was observed in the monitored sites, accompanied by a rise of 16% of the surface occupied by macroalgae. The protocol set up by the National Park of Guadeloupe was found to be efficient to follow the temporal dynamics of benthic reef communities.

Status of Coral Reefs in Lagonoy Gulf, Eastern Bicol, Philippines with Emphasis on Marine Protected Areas

Status of coral reef health of 8 Marine Protected Areas (MPA), 6 adjacent MPA reefs and 5 regular reefs of Lagonoy Gulf were assessed from December 2017 to August 2018 and compared with previous gulf-wide assessment results in 1994 and 2004. Underwater photo transect (UPT) method was utilized to collect benthic lifeform information and coral point count with excel extensions (CPCe) was used to analyzed benthic data. Results showed that present live coral cover in MPAs are low with 26% as compared to adjacent MPA reef areas (30%) and regular reef stations (33%). A downtrend was noted from 1993 – 2004 with 10% decline of MPA reefs while from 2004 to 2018 decrease was almost 20% and from 1993 to 2018 an average fall of 25% was detected. Overall, Lagonoy Gulf reef health is declining and can be attributed to both natural and fisheries activities, as evidenced by almost 20 typhoons affecting the Region per year with a super typhoon at least every 5-10 years and the heavy dependence of fishing communities on reef fishes respectively. However, non-MPA reefs decline was observed to very minimal as compared for both MPA and adjacent MPA reefs ranging from 1% to 6%. With this, MPA management schemes should be revisited and amended to improve and strengthen MPA governance, direction and strategies.

Implications of 2D versus 3D surveys to measure the abundance and composition of benthic coral reef communities

A paramount challenge in coral reef ecology is to estimate the abundance and composition of the communities residing in such complex ecosystems. Traditional 2D projected surface cover estimates neglect the 3D structure of reefs and reef organisms, overlook communities residing in cryptic reef habitats (e.g., overhangs, cavities), and thus may fail to represent biomass estimates needed to assess trophic ecology and reef function. Here, we surveyed the 3D surface cover, biovolume, and biomass (i.e., ash-free dry weight) of all major benthic taxa on 12 coral reef stations on the island of Curaçao (Southern Caribbean) using structure-from-motion photogrammetry, coral point counts, in situ measurements, and elemental analysis. We then compared our 3D benthic community estimates to corresponding estimates of traditional 2D projected surface cover to explore the differences in benthic community composition using different metrics. Overall, 2D cover was dominated (52 ± 2%, mean ± SE) by non-calcifying phototrophs (macroalgae, turf algae, benthic cyanobacterial mats), but their contribution to total reef biomass was minor (3.2 ± 0.6%). In contrast, coral cover (32 ± 2%) more closely resembled coral biomass (27 ± 6%). The relative contribution of erect organisms, such as gorgonians and massive sponges, to 2D cover was twofold and 11-fold lower, respectively, than their contribution to reef biomass. Cryptic surface area (3.3 ± 0.2 m2 m−2planar reef) comprised half of the total reef substrate, rendering two thirds of coralline algae and almost all encrusting sponges (99.8%) undetected in traditional assessments. Yet, encrusting sponges dominated reef biomass (35 ± 18%). Based on our quantification of exposed and cryptic reef communities using different metrics, we suggest adjustments to current monitoring approaches and highlight ramifications for evaluating the ecological contributions of different taxa to overall reef function. To this end, our metric conversions can complement other benthic assessments to generate non-invasive estimates of the biovolume, biomass, and elemental composition (i.e., standing stocks of organic carbon and nitrogen) of Caribbean coral reef communities.

Coral reef condition in the coastal waters of Kei Besar Island, Southeast Maluku-Indonesia

A study on coral reefs condition in the coastal waters of Kei Besar Island was conducted in 2019 with the aimed to provide data on taxa composition, density and colony diameter of stony corals, coral reefs condition, and ecological indices of the coral community. It was found during the study that there are 17 families of stony coral, which consist of 62 genera and 206 species. Among those species of stony coral, 79 species are classified as protected species and 50 species as ornamental coral. Coral families of Acroporidae, Faviidae, Fungiidae, and Poritidae have high species richness. The density of stony coral colonies between reef stations ranged from 3.0 colonies m−2 (low) with a relatively large colony diameter until 16.3 colonies m−2 (high) with a small coral colony diameter. The only one reef station was in Excellent condition, while seven reef stations in Good, four reef stations in Fair, and two coral reef sites were in Poor condition. The coral community in the coastal waters of Kei Besar Island had moderate species diversity of stony coral and low species dominance with stable condition.

A potential new threat on the coral reefs of Puerto Rico: The recent emergence of Ramicrusta spp.

AbstractThe rapid appearance of Ramicrusta spp. is described and analyzed from 40 permanent monitoring coral reef stations in Puerto Rico. Before 2016, Ramicrusta had not been observed from any of the reef monitoring stations. By 2018, it was present at 76% of all the monitoring stations. Ramicrusta was the dominant substrata type at all of the shallow reef sites sampled on the east coast (e.g., Fajardo, Culebra, and Vieques), reaching a cover (±SE) as high as 63.0 ± 5.8%. The spread of Ramicrusta occurred at the expense of historically resilient living benthic elements, such as turf algae. Since its detection in 2016, colonization of hard substrata by Ramicrusta remained constant, with the exception of two shallow reefs in Fajardo and Culebra, where the cover was significantly reduced by the scouring and or abrasive effects of two major hurricanes. The ecological implications of Ramicrusta prevalence on Puerto Rican reefs remain unclear; however, increasing herbivory might be a useful mitigation tool in the reduction of Ramicrusta abundance on coral reefs.

SPECIES COMPOSITION AND DISTRIBUTION OF MOLLUSCA AND ECHINODERMATA ON CORAL REEFS IN SURVEY ON AKADEMIK OPARIN RC IN 2016–2017

A study on the species composition and distribution of Mollusca and Echinodermata on coral reefs from Quang Tri to Binh Thuan was conducted during the field survey between Vietnam and Russia on the AKADEMIK OPARIN RC vessel in 2016 and 2017 at 39 reef stations. 150 species were identified belonging to 100 genera, 50 families, 22 orders, 7 classes distributed on coral reefs. The species composition of mollusca and echinodermata was different between study areas.

Summer micro- and mesozooplankton from the largest reef system of the South Atlantic Ocean (Abrolhos, Brazil): Responses to coast proximity

Zooplankton samples were collected in summer and in three distinct Neotropical areas (the coastal reef arc, the outer reef arc and the Abrolhos Archipelago). Two stations in each sampling area were established (a reef station and an outer station) to sampling zooplanktonic assemblage with two different mesh sizes (64- and 200-μm plankton nets). Approximately 110 taxa were identified, and the assemblages from the two nets were significantly different. Zooplankton abundances were three orders of magnitude higher in the 64-μm net samples with an average abundance of 217,000 ± 93,418 ind m−3 (64-μm net) and 189 ± 122 ind m−3 (200-μm net). A permutational multivariate analysis of variance (PERMANOVA) of the zooplankton community structure revealed significant differences between all three regions and showed a heterogeneous distribution of these animals, even though no significant differences were observed in terms of abundance for both net catches (two-way ANOVA, P > 0,05). SIMPER analyses showed that most highly abundant taxa occurred in all sampling areas. Though, some other taxa were clearly identified as characteristic of a particular area by their relative frequency, rather than relative abundance. It is hypothesized that variations in suspended particle concentration play an important role in the observed differences in community composition. Our results suggest that the pelagic components of these reef zooplankton assemblages may be as important as demersal zooplankters to benthic-pelagic coupling. Because the much higher abundance of the microzooplankton assemblages compared to the mesozooplankton is a common feature of reef communities, the studies that use only coarse nets miss assessing the contribution of a large and important portion of the reef zooplankton assemblage and therefore misinterpret the community as a whole.

Is gardening corals of opportunity the appropriate response to reverse Philippine reef decline?

Hard coral cover (HCC) in the Philippines has been declining over the past decades. Restoration practices that utilize “gardening” corals of opportunity (COPs) are actively being adopted throughout the country. However, the use of COPs in coral gardening has not yet been examined in terms of its effectiveness in addressing nationwide‐scale reef decline. The feasibility of using COPs for coral gardening was determined through a spreadsheet model that derives COP numbers needed to increase HCC in a reef. The model showed that 280,112 COPs of 5‐cm radius need to be transplanted to increase HCC in a hectare of reef from 0% to 22%, the current national average. Annual COP mortality must be less than 31.5% to achieve an increase in HCC above 22% over a span of 10 years following a gardening effort. Actual counts and generic composition of available COPs were recorded from transects in 20 reef stations across three locations in the Philippines (Lian, Luzon; Lubang Island; and Balabac, Palawan). Natural COP densities suggest that large areas of healthy reefs must be searched to obtain enough COPs for an effective gardening effort. Furthermore, the COPs measured in Lian were below the recommended fragment size for transplantation, thus needing nursery rearing to attain the 5‐cm radius prescribed for increased probability of transplant survivorship. These findings indicate that applying coral gardening at a nationwide scale is not likely to be feasible, effective, or sustainable.

Mortality, recovery, and community shifts of scleractinian corals in Puerto Rico one decade after the 2005 regional bleaching event.

This work analyzes the mortality, recovery, and shifts in the composition of scleractinian corals from Puerto Rico one decade after the 2005 regional coral bleaching event. Temporal and spatial patterns of coral community structure were examined using a stratified, non-random sampling approach based on five permanent transects per reef at 16 reef stations. A negative correlation between percent coral cover loss and light attenuation coefficient (Kd490) was observed, suggesting that light attenuation, as influenced by water turbidity and depth, played a major role in coral protection during the bleaching event (“sunblock effect”). Responses of coral assemblages varied after the bleaching event, including shifts of cover from massive corals (Orbicella spp.) to opportunistic (Porites astreoides) and branching corals (Madracis auretenra, P. porites) and/or turf algae; partial recovery of reef substrate cover by O. annularis complex; and no measurable changes in coral assemblages before and after the event.

Coral bleaching in the Caramuanas reef (Todos os Santos Bay, Brazil) during the 2010 El Niño event

Episodes of coral bleaching related to El Niño events have been increasing in frequency and severity. This phenomenon is cited as a major cause of degradation of coral reefs. This study evaluates the effects of coral bleaching on the Caramuanas reef community, which occurred during the southern hemisphere summer of 2009/2010. Within this period the sea surface temperature of 31°C and thermal anomalies up to almost 1°C were recorded. During and after this El Niño event, frequency and severity of bleaching, live coral cover, number of colonies, class size, disease occurrence, and mortality rate were monitored on corals larger than 20 cm in diameter. The samples were taken at twelve fixed transects, in three reef stations. Statistical analysis showed that the severity of bleaching was different between the two periods, during and after the 2010 ENSO event. The Caramuanas reef showed sublethal bleaching effects indicating that this reef is tolerant to bleaching when the temperature anomalies do not exceed 0.75°C within one week.

In hospite Symbiodinium photophysiology and antioxidant responses in Acropora muricata on a coast-reef scale: implications for variable bleaching patterns

Understanding susceptibility to bleaching may indicate how corals cope with increasing seawater temperatures resulting from climate change. In Belle Mare lagoon, Mauritius, Acropora muricata colonies at reef sites but not near the coast exhibited bleaching. We compared seawater temperatures and light intensity both on a summer day and a winter day at a reef station and a near-coast station. The total phenolic contents, non-enzymatic antioxidant activities of the coral holobiont, in situ photophysiological parameters of in hospite Symbiodinium as well as their cladal diversity were assessed. Both sites had comparable maximum temperatures but fluctuations were higher in the near-coast station (2–3 °C) compared to the reef station (1–1.5 °C) on both days. Light intensity was higher on the summer day than the winter day at both stations. Higher total phenolic contents and ferrous reducing antioxidant potential were observed in near-coast colonies than in reef colonies on the summer day. Only Clade A-like Symbiodinium sp. variants were detected at both locations, but higher maximum relative electron transport rates and maximum non-photochemical quenching were measured in near-coast colonies. Our data show that the near-coast colonies exhibited enhanced photophysiological responses, antioxidant activities and increased total phenolic contents in response to higher thermal and light fluctuations. This acclimatization may explain the variability in bleaching along a coast-reef scale.

Over a Decade of Change in Spatial and Temporal Dynamics of Hawaiian Coral Reef Communities

The Hawai‘i Coral Reef Assessment and Monitoring Program (CRAMP) was established in 1999 to describe spatial and temporal variation in Hawaiian coral reef communities in relation to natural and anthropogenic factors. In this study, we analyzed changes over a 14-yr period (1999 to 2012) based on data from 60 permanent reef stations at 30 sites in the main Hawaiian Islands. Overall mean statewide coral cover, richness, and diversity did not vary significantly since the initial surveys, although local variations in coral cover trends were detected. The greatest proportion of stations with significant declines in coral cover was found on the island of Maui (0.4), and Hawai‘i Island had the highest proportion of stations with significant increases (0.67). Trends in coral cover at some stations varied over time due to acute (e.g., crown of thorns outbreak) and chronic (e.g., sedimentation) disturbances. Stations with increasing coral cover with the potential for recovery from disturbances were identified for possible management actions in the face of future climate change. The Hawaiian archipelago, located in the center of the subtropical Pacific, has experienced a temporary reprieve from steadily increasing temperatures over the past several decades due to a downturn of temperatures at the end of the last cycle of the Pacific Decadal Oscillation (PDO) in 1998. In 2014, however, temperatures increased dramatically in Hawai‘i, resulting in a major coral bleaching event with associated mortality. Temperature models predict severe bleaching events to increase in frequency and intensity in coming decades with concomitant decline in Hawaiian corals. Trends reported in this study provide a baseline that can later be used to test this predicted decline associated with future warming.

Use of Integrated Landscape Indicators to Evaluate the Health of Linked Watersheds and Coral Reef Environments in the Hawaiian Islands

A linkage between the condition of watersheds and adjacent nearshore coral reef communities is an assumed paradigm in the concept of integrated coastal management. However, quantitative evidence for this "catchment to sea" or "ridge to reef" relationship on oceanic islands is lacking and would benefit from the use of appropriate marine and terrestrial landscape indicators to quantify and evaluate ecological status on a large spatial scale. To address this need, our study compared the Hawai'i Watershed Health Index (HI-WHI) and Reef Health Index (HI-RHI) derived independently of each other over the past decade. Comparisons were made across 170 coral reef stations at 52 reef sites adjacent to 42 watersheds throughout the main Hawaiian Islands. A significant positive relationship was shown between the health of watersheds and that of adjacent reef environments when all sites and depths were considered. This relationship was strongest for sites facing in a southerly direction, but diminished for north facing coasts exposed to persistent high surf. High surf conditions along the north shore increase local wave driven currents and flush watershed-derived materials away from nearshore waters. Consequently, reefs in these locales are less vulnerable to the deposition of land derived sediments, nutrients and pollutants transported from watersheds to ocean. Use of integrated landscape health indices can be applied to improve regional-scale conservation and resource management.

Epilithic community development on artificial reefs deployed along a cross-shelf environmental gradient off Paraná state, southern Brazil

Concrete modules were deployed on the bottom of the 11, 18 and 30 meters isobaths along a cross-shelf hydrographic gradient off Paraná State, Southern Brazil, with the purpose of studying the colonization of sessile epilithic macroinvertebrates on artificial surfaces. After one year of submersion a total of 63 species of epilithic organisms were identified, dominated by Ostrea puelchana, Chthamalus bisinuatus, Balanus cf spongicola, Astrangia cf rathbuni, Didemnum spp, poryphers and bryozoans. Diversity index and percent cover at reef stations placed at 11, 18 and 30 meters isobaths were respectively 2.28 and 66.7%, 2.79 and 96.6% and 1.66 and 77.4%. Differences of general community structure among the three assemblages were not clearly related to the general environmental conditions at the bottom layers near the reef stations. Turbidity and larval abundance are discussed as important factors affecting colonization processes. Results indicate that depths between 15-20 meters are more suitable for the implementation of large scale artificial reef systems in the inner shelf off Paraná and, possibly, throughout the inner shelves off southern Brazil with similar hydrographic conditions.

Low community photosynthetic quotient in coral reef sediments

Fluxes of dissolved inorganic carbon and oxygen at the water–sediment interface were measured at eight coral reef stations (Indian Ocean) in summer and winter. The dark fluxes provided the community respiratory quotient (CRQ = dissolved inorganic carbon release / oxygen uptake) and the diurnal fluxes corrected from the dark fluxes gave the community photosynthetic quotient (CPQ = oxygen gross release / dissolved inorganic carbon gross uptake). The CRQ and the winter CPQ were not significantly different from 1. Summer CPQ (0.79; SD 0.02) was significantly lower than 1 due to the combined effect of the daily evolution of the community respiration and the discrepancy between the daily evolution in community oxygen respiration and community carbon respiration. These results highlight the importance of measuring simultaneously the benthic community production and respiration for long term integrated data sets, instead of the traditional daily or seasonal budget calculations from limited measures of community respiration. To cite this article: D. Taddei et al., C. R. Biologies 331 (2008).

Actividad alimentaria de los peces herbívoros y su impacto en arrecifes con diferente nivel de degradación antrópica

The feeding activity of three herbivorous fishes (Sparisoma viride, Scarus iserti and Acanthurus coeruleus) and its impact on two coral reefs were studied during the dry (February) and rainy (August) seasons of 2006 in Cuba. One of the reef stations is at the "Acuario" dive point in the Guanahacabibes National Park, and is relatively pristine. The second one is located at the north coast of Havana City facing the Instituto de Oceanología (IdO) and is subject to pollution and fishing pressures. Herbivore fish composition was analized, and foraging intensity was measured for all Acanthurid and Scarid species, by counting fish bites in 1 m2 during five minute intervals (25 replicates). Concurrently, species foraging intensity was measured for juvenile, intermediate, and adult phases, counting fish bites during 10 minutes intervals (10 replicates). Algal consumption rate was estimated using a coefficent of consumed biomass per bite, for each size class. The algal cover was sampled at 20 m linear transects with four replicates at each site. Food items were assessed sampling algae at the observed bitten substrates. Compared to Acuario, herbivores in IdO showed lower species richness and higher density of small size fishes, but large-sized parrotfish was almost absent due to intense fishing. The highest bite rate was observed for the smallest fish size, but net consumption rate was three times greater for medium and great size fishes, which were more abundant in the protected area. Algal cover was lower in Acuario, while in IdO it was very high, and coral cover was very low. In both locations epiphytic algae were the preferred food. These results support generalizations referring to the importance of great size herbivores fishes in controlling excesive algal proliferation on coral reefs.

Establishment and Initial Analysis of Deep Reef Stations (32-40 M) at the East Flower Garden Bank

Establishment and Initial Analysis of Deep Reef Stations (32-40 M) at the East Flower Garden Bank

Factors influencing the short-term variation in phytoplankton composition and biomass in coral reef waters

The short-term temporal dynamics of phytoplankton composition was compared among coral reef waters, the adjacent ocean and polluted harbour water from July until October along the south-western coast of Curacao, southern Caribbean. Temporal variations in phytoplankton pigment 'fingerprints' (zeaxanthin, chlorophyll b, 19′-hexanoyloxyfucoxanthin, fucoxanthin, 19′-butanoyloxyfucoxanthin, chlorophyll c 2 and c 3 relative to chlorophyll a) in the ocean were also observed in waters overlying the reef. However, with respect to specific pigments and algal-size distribution, the algal composition in reef waters was usually slightly different from that in the oceanic water. Phytoplankton biomass (chlorophyll a) was either higher or lower than in the oceanic water. The relative amount of fucoxanthin and peridinin was usually higher, and the relative and absolute amount of zeaxanthin was significantly lower than in oceanic water. Zeaxanthin-containing Synechococci were significantly reduced in reef water. Average algal cell size increased from the open water to the reef and the harbour entrance. Large centric diatoms (>20 m O) were better represented in reef than in oceanic water. In reef-overlying waters, the nitrate and nitrite concentrations were higher than in oceanic water. In front of the town, anthropogenic eutrophication (sewage discharge and ground water seepage) resulted in higher NH4, NO3 and PO4 concentrations than at other reef stations. This concurred with significantly enhanced phytoplankton biomass (chlorophyll a), chlorophyll c 2 and peridinin amounts at Town Reef compared with the other reef stations. Polluted harbour water usually showed the highest phytoplankton biomass of all stations, dominated by diatoms and dinoflagellates. Conditions in reef waters and harbour water promoted the occurrence and the relative abundance of diatoms and dinoflagellates. Harbour water did not influence the phytoplankton composition and biomass at reef stations situated >5 km away from the harbour entrance. We conclude that phytoplankton undergoes a shift in algal composition during transit over the reef. The dominant processes appear to be selective removal of zeaxanthin-containing Synechococcus (by the reef benthos) and (relative) increase in diatoms and dinoflagellates. The difference in the phytoplankton composition between reef and oceanic waters tends to increase with decreasing dilution of reef water with ocean water.

Linkage of small-scale spatial variations in DOC, inorganic nutrients and bacterioplankton growth with different coral reef water types

This study focuses on links of dissolved organic carbon (DOC), inorganic nutrients (DIN and DIP) and bacterioplankton growth with specific coral reef water types. At 5 reef stations along the SW coast of Curacao (Netherlands Antilles), 6 different water types (4 reef water types (live coral surface contact water, reef crevice water, reef bottom water, reef overlying water) and 2 reference water types collected offshore from each station at 2 and 8 m depth) were analysed for DOC, DIN and DIP, bacterial production and abundance. Consistent patterns were found: reef waters were enhanced in DIN, DIP and specific bacterial growth rate (µn) compared to offshore waters. DOC, DIP, and µn were higher close to the reef bottom than in the reef overlying water. Coral surface contact water was significantly enhanced in DOC compared to reef crevice and reef bottom water, suggest- ing that the major source of DOC in reef waters are the live corals. DIN concentration was highest in reef crevice water, suggesting that crevices are the major net N-regenerating spaces on reefs, more important than the reef bottom between corals. Small-scale DIP distribution suggested net P regen- eration in reef crevice and coral surface contact water. The highest specific growth rates of bacterio- plankton were found in the coral surface contact water, with slightly lower rates in reef crevice water. Experiments showed that the labile DOC fraction (LDOC) in reef crevice water was substantially smaller than in coral surface contact and reef overlying water, which suggests that crevices are apparently sinks of LDOC. In reef crevice and reef bottom water the low substrate LDOC:DIN ratios suggest that LDOC might be the growth-limiting factor of bacterioplankton in these water types. In coral surface contact and reef overlying water the substrate LDOC:DIN ratios of more than 40 (and LDOC:DIP ratios of over 800) and the significant relations between µn and DIN (DIP) suggest nutrient limitation of bacterioplankton growth in these water types. This study clearly illustrates the close link in reef waters between coral reef benthos and bacterioplankton trophodynamics.