Reef Edge Research Articles

Coral boulders on Melekeok reef in the Palau Islands: An indicator of wave activity associated with tropical cyclones

Waves generated by tropical cyclones and tsunamis cause various impacts such as coastal erosion and damage to infrastructure. The intensity of tropical cyclones will probably increase in the near future as a result of global warming; therefore, predicting the likely impacts of these storms is a prime concern. Boulder deposits are one of the key proxies that assist our understanding of previous tropical cyclones and tsunamis, and are important if we are to accurately project their future impacts. In December 2012, Typhoon Bopha hit the Palau Islands and many boulders were probably deposited on the east coast of Babeldaob Island during the event. This area is one of the few locations where it is possible to distinguish between deposits that were generated by tropical cyclone waves and tsunamis. This study records the distribution of boulders from the shore to the reef crest at Melekeok reef on Babeldaob Island and evaluates the relationship between the movement of boulders and the hydraulic forces generated by the waves using a hydrodynamic model and wave calculations. In addition, this study projects the coastal impacts of tropical cyclone waves in the near future. Many boulders have been deposited on the reef crest within 100 m of the reef edge, and the maximum weight of the boulders is 2.2 tons. The boulders are composed of massive corals (e.g., Platygyra) and they originated from the upper reef slope. The results of the hydrodynamic modeling indicate that these boulders were transported and deposited by the waves generated by Typhoon Bopha (significant wave height = 8.7 m) or TCs with a similar intensity of Typhoon Bopha. Moreover, there are no boulder deposits at the shore, which implies that the reef has not been affected by tsunamis. Even if one or more tsunamis have inundated the reef, the associated hydraulic forces appear to have been lower than those of Typhoon Bopha. These findings indicate that Typhoon Bopha has probably generated the most intense wave event in recent times. However, it is likely that tropical cyclones more intense than Typhoon Bopha will affect the reef in the near future as the climate continues to warm through the 21st century. Consequently, the study site will probably face an increased risk of coastal erosion and destruction of property, if no plans are developed to reduce and manage such impacts.

Boulder emplacement and remobilisation by cyclone and submarine landslide tsunami waves near Suva City, Fiji

The characteristics of a reef-top boulder field created by a local submarine landslide tsunami are presented for the first time. Our examination of large reef-derived boulders deposited by the 1953 tsunami near Suva City, Fiji, revealed that shorter-than-normal-period tsunami waves generated by submarine landslides can create a boulder field resembling a storm boulder field due to relatively short boulder transport distances. The boulder-inferred 1953 tsunami flow velocity is estimated at over 9ms−1 at the reef edge. Subsequent events, for example Cyclone Kina (1993), appear to have remobilised some large boulders. While prior research has demonstrated headward retreat of Suva Canyon in response to the repeated occurrence of earthquakes over the past few millennia, our results highlight the lingering vulnerability of the Fijian coastlines to high-energy waves generated both in the presence (tsunami) and absence (storm) of submarine failures and/or earthquakes. To explain the age discrepancies of U-Th dated coral comprising the deposited boulders, we introduce a conceptual model showing the role of repeated episodes of tsunamigenic submarine landslides in removing reef front sections through collapse. Subsequent high-energy wave events transport boulders from exposed older sections of the reef front onto the reef where they are deposited as ‘new’ boulders, alongside freshly detached sections of the living reef. In similar situations where anachronistic deposits complicate the deposition signal, age-dating of the coral boulders should not be used as a proxy for determining the timing of the submarine landslides or the tsunamis that generated them.

Environmental Drivers of Variation in Bleaching Severity of Acropora Species during an Extreme Thermal Anomaly

High sea surface temperatures caused global coral bleaching during 2015-2016. During this thermal stress event, we quantified within- and among-species variability in bleaching severity for critical habitat-forming Acropora corals. The objective of this study was to understand the drivers of spatial and species-specific variation in the bleaching susceptibility of these corals, and to evaluate whether bleaching susceptibility under extreme thermal stress was consistent with that observed during less severe bleaching events. We surveyed and mapped Acropora corals at 10 sites (N = 596) around the Lizard Island group on the northern Great Barrier Reef. For each colony, bleaching severity was quantified using a new image analysis technique, and we assessed whether small-scale environmental variables (depth, microhabitat, competition intensity) and species traits (colony morphology, colony size, known symbiont clade association) explained variation in bleaching. Results showed that during severe thermal stress, bleaching of branching corals was linked to microhabitat features, and was more severe at reef edge compared with lagoonal sites. Bleaching severity worsened over a very short time-frame (~1 week), but did not differ systematically with water depth, competition intensity, or colony size. At our study location, within- and among-species variation in bleaching severity was relatively low compared to the level of variation reported in the literature. More broadly, our results indicate that variability in bleaching susceptibility during extreme thermal stress is not consistent with that observed during previous bleaching events that have ranged in severity among globally dispersed sites, with fewer species escaping bleaching during severe thermal stress. In addition, shaded microhabitats can provide a refuge from bleaching which provides further evidence of the importance of topographic complexity for maintaining the biodiversity and ecosystem functioning of coral reefs.

The effects of intertidal oyster reef habitat characteristics on faunal utilization

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 581:57-70 (2017) - DOI: https://doi.org/10.3354/meps12261 The effects of intertidal oyster reef habitat characteristics on faunal utilization Marc H. Hanke1,2,*, Martin H. Posey1, Troy D. Alphin1 1Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 S. College Road, Wilmington, NC 28403, USA 2Present address: Honors College, University of Houston, 212 MD Anderson Library, 4333 University Dr., Houston, TX 77204-2001, USA *Corresponding author: marc.h.hanke@gmail.com ABSTRACT: The presence, abundance, and distribution of organisms within a landscape are highly dependent on the composition, quality, and configuration of habitat patches. Intertidal oyster Crassostrea virginica reefs provide a structured habitat for many organisms; however, declining oyster populations have induced reef fragmentation and loss. Over 2 years (2011-2012), we evaluated naturally occurring fringing and patch intertidal oyster reefs in southeastern North Carolina, USA, to determine how varied reef type, size, and distance from edge to interior influenced the associated benthic macrofauna and mobile nekton. In addition, the effects of size and edge vs. interior were examined on constructed intertidal reefs at 2 different locations. On the natural reefs, species richness of benthic macrofauna and mobile nekton were significantly increased on fringing reefs. Benthic macrofauna richness significantly decreased on large natural reefs, whereas mobile nekton richness significantly increased off of large reefs. Further, associated benthic macrofauna richness significantly decreased along the reef edge, whereas mobile nekton diversity increased along the reef/open bottom interface. Species richness and densities for benthic macrofauna increased with created reef size, while there was greater species richness and diversity and dissimilar communities for mobile nekton along constructed reef edges. Habitat specificity may influence utilization for mobile nekton, as resident organisms with limited vagility had a stronger response to habitat characteristics. Thus, utilization of intertidal oyster reefs can be highly structured by habitat characteristics on many scales, and should be considered when examining species interactions, ecosystem management, and future restoration efforts. KEY WORDS: Habitat characteristics · Habitat heterogeneity · Patch size · Edge effects · Mobile nekton · Benthic macrofauna · Habitat fragmentation · Habitat restoration · Oyster reefs · Crassostrea virginica Full text in pdf format PreviousNextCite this article as: Hanke MH, Posey MH, Alphin TD (2017) The effects of intertidal oyster reef habitat characteristics on faunal utilization. Mar Ecol Prog Ser 581:57-70. https://doi.org/10.3354/meps12261 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 581. Online publication date: October 13, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.

Do they stay or do they go? Acoustic monitoring of whale sharks at Ningaloo Marine Park, Western Australia.

Whale sharks Rhincodon typus were monitored via acoustic transmitters at the northern end of Western Australia's Ningaloo Marine Park to establish the extent to which the species inhabits the region beyond the whale-shark ecotourism industry season, which usually extends from March to August in each year. Despite the vast majority (c. 98%) of photographic submissions of R. typus from Ningaloo Reef being between March and August, acoustic detections from the tagged R. typus at Ningaloo were recorded in all months of the year, but do not preclude the occurrence of extended absences. It is concluded that as a species, R. typus occurs year round at Ningaloo, where it generally remains in close proximity to the reef edge, but that some individuals move outside of the detection range of the array for extended periods.

Applications of unmanned aerial vehicles in intertidal reef monitoring

Monitoring of intertidal reefs is traditionally undertaken by on-ground survey methods which have assisted in understanding these complex habitats; however, often only a small spatial footprint of the reef is observed. Recent developments in unmanned aerial vehicles (UAVs) provide new opportunities for monitoring broad scale coastal ecosystems through the ability to capture centimetre resolution imagery and topographic data not possible with conventional approaches. This study compares UAV remote sensing of intertidal reefs to traditional on-ground monitoring surveys, and investigates the role of UAV derived geomorphological variables in explaining observed intertidal algal and invertebrate assemblages. A multirotor UAV was used to capture <1 cm resolution data from intertidal reefs, with on-ground quadrat surveys of intertidal biotic data for comparison. UAV surveys provided reliable estimates of dominant canopy-forming algae, however, understorey species were obscured and often underestimated. UAV derived geomorphic variables showed elevation and distance to seaward reef edge explained 19.7% and 15.9% of the variation in algal and invertebrate assemblage structure respectively. The findings of this study demonstrate benefits of low-cost UAVs for intertidal monitoring through rapid data collection, full coverage census, identification of dominant canopy habitat and generation of geomorphic derivatives for explaining biological variation.

Surf beat-induced overwash during Typhoon Haiyan deposited two distinct sediment assemblages on the carbonate coast of Hernani, Samar, central Philippines

Wave set-up steepened and accentuated the storm surge during Typhoon Haiyan in November 2013 resulting in bore-like flooding with surge heights of 7m and flow velocities reaching 5ms−1 on the open-sea coastal plain near Hernani. This study investigates two distinct sediment assemblages left behind by the coastal flooding associated with this surge. The first assemblage consists of numerous coastal boulders that now occupy the reef flat, and the second pertains to a laterally extensive sand sheet that blanketed the coastal plain up to ~300m inland. The majority of the boulders has b axes between 1 and 2m, weigh no >10t, and were originally submerged on the reef edge. The boulders found more landwards of the reef edge were potentially lying loosely on the reef flat prior to Haiyan. In contrast, the coarse carbonate sand sheet starts at ~10m inland of the current shoreline and has a maximum thickness of 10cm and gradually thins to 3mm at ~300m inland. The Haiyan sand contains moderate concentrations of foraminifera (Amphistegina spp., Baculogypsina sphaerulata, and Peneroplis spp.) that were both abraded and unaltered, pointing to a reef flat and beach source for the sand. Sediment transport inverse modeling complements previous flow velocity estimates using numerical modeling, which altogether indicate sustained high-velocity overland flow despite the presence of coral reefs and mangroves as natural defenses to extreme waves.

Study on wave-induced setup over fringing reefs in the presence of a reef crest

It has been well observed that a reef crest (ridge) may be present at the reef edge, but so far very few published studies focusing on the effects of such reef-crest on the wave dynamics over fringing reefs. To understand the role of a reef-crest configuration in determining breaking-wave induced setup over the reef flat, a series of experiments were carried out in a wave flume using an idealized fringing reef model with a reef crest. Experimental results were reported for a trapezoidal reef crest with five reef-crest widths under a series of monochromatic waves. Also examined was the reef without a reef crest. Data analysis shows that larger energy dissipation associated with smaller surfzone width around the reef edge occurred with a wider reef crest. The maximum wave-induced setup on the reef flat in the presence of the reef crest was significantly larger than that without, and it also increased with increasing reef-crest width. The reef-crest submergence was found to be a primary parameter controlling the magnitude of wave setup on the reef flat provided that the reef crest was sufficient wide. An alternative semi-analytical 1DH model based on the balance of cross-shore momentum was proposed. The model was validated by present laboratory data as well as three existing 1DH laboratory studies. Comparing with other two representative semi-analytical models in the literature showed that the proposed model was capable of better reproducing the maximum wave-induced setup on the reef flat for a variety of reef profiles with/without a reef crest, different reef-crest water levels, as well as both monochromatic and spectral waves. The model parameter was physically related to the two characteristic lengths in the surf zone and its value was dependent on the fore-reef slope as well as the presence of a reef crest. The 1DH model was also satisfactorily applied to a fringing reef in field conditions where the effects of fore-reef friction and back-reef lagoon were not important.

Importance of outer reef slopes for commercially important fishes: implications for designing a marine protected area in the Philippines

A passive acoustic telemetry survey was conducted to determine occurrence patterns of commercially important fishes on a steep reef slope along a marine protected area (MPA) in the southern Philippines, where the outer reef edge is often set as an offshore MPA boundary. Based on 4–61 days of tracking data from 21 detected individuals of five species (Lutjanus argentimaculatus, Lutjanus monostigma, Lethrinus atkinsoni, Lethrinus obsoletus, and Siganus guttatus; 20.7–69.2 cm fork length) caught near the reef slope of the MPA, S. guttatus occurred most frequently on the reef flat of the MPA, whereas all individuals of the four lutjanid and lethrinid species were primarily (99.4–100%) detected near the reef slope, and nine individuals (56.3% of these four species) of three of these species (not L. obsoletus) most likely used the shallow (≤10 m) and deep (≥20 m) layers, and thus, middle layers of the slope. These findings indicate that commercially important lutjanid and lethrinid species predominantly and vertically used the areas near the reef slope, suggesting the importance of fully including reef slopes in MPAs to enhance their effectiveness for the conservation of such fishes.

Distribution of platform edge reefs and beach as well as their major controlling factors over the Changxing-Feixianguan formations in northeast Sichuan Basin, China

The platform facie, platform edge facie, slope, and basin facie were developed in the Chengkou-Western Hubei Trough zones during the Upper Permian Changxing Formation's Early Triassic Feixianguan period; during this time the platform edge had the most favorable sedimentary facie. The Changxing Formation was composed of three sections in which the second section was rich in framework reef, whereas the third one was rich in micro-reefs at the bottom. Recently, it has been discovered that abundant platform edge shoals are developed in the third member and that oolitic shoals with large thickness are widely distributed. This paper systematically investigated the influence of the changes in reef-building organism system on the development of organic reefs. The results show that the distribution of bank belts is determined through paleogeography framework. The rapid change of relative sea level affects the formation and movement of bank belts. In addition, the regional tectonic activity controls the distribution and transformation of the bank belts. Finally, the prospective zone in the Chengkou-Western Hubei area was evaluated and divided into four favorable zones, in which the Wanyuan-Yunyang area was deemed to be most advantageous.

Two new methods for sampling zooplankton and larval assemblages in tropical reef ecosystems

Sampling mobile zooplankton on reefs is a major challenge, mainly due to the problems faced when towing plankton nets inside complex reef mosaics. This study presents two new systems that permit precise point sampling of micro- and mesozooplankton and larvae of invertebrates and fish: the Channel Midwater Neuston Net (CMNN) and the Reef Edge Net (REN). Both are moored systems that are equipped with 64- and 300-μm mesh nets. The CMNN system was designed for continuous sampling in tidal channels between reef patches. It samples at three precise depth layers (epineuston: 0m to 0.075m, hyponeuston: 0.075m to 0.225m, 1m layer: 0.925m to 1.075m depth). The REN system allows sampling at precise, adjustable depths at given distances from the reef edge. The objective of the REN is to collect organisms that are washed from reef tops and reef edges with the ebb flow. The performance of these two new systems was evaluated and compared with results obtained by using common Ring nets in horizontal subsurface tows. Fieldwork was performed at two reef patches of the Tamandaré reef system (Brazil) in November 2015. The CMNN and REN showed similar performance in comparison with Ring net tows, capturing microzooplankton communities as well as veliger, polychaete, decapod and barnacle larvae in similar abundances. For the mesozooplankton, the REN presented a similar performance to the Ring net tows, efficiently capturing decapod crustacean and fish larvae as well as fish eggs. The CMNN showed lower abundance of decapod larvae and fish eggs but showed a good performance for the quantification of fish larvae. The two new passive nets showed a high effectiveness in collecting larvae and advantages over tows with Ring nets since they stay for several hours continuously capturing larval aggregations during spawning events. This high capturing efficiency is probably related to the avoidance of sample reflux in the long nets that sink and close at slack tide for the CMNN, and due to the long, trap-like design with funnel-shaped internal “anti-reflux” nets, for the REN. Navigation safety and easy handling are further advantages of these moored systems, as compared to towing plankton nets at nighttime between reefs. CMNN and REN may become useful tools for the study of zooplankton and larval ecology and for integrated long-term studies in marine protected areas and reefs under multiple human impacts.

Typhoon Haiyan's sedimentary record in coastal environments of the Philippines and its palaeotempestological implications

Abstract. On 8 November 2013, category 5 Supertyphoon Haiyan made landfall on the Philippines. During a post-typhoon survey in February 2014, Haiyan-related sand deposition and morphological changes were documented at four severely affected sites with different exposure to the typhoon track and different geological and geomorphological settings. Onshore sand sheets reaching 100–250 m inland are restricted to coastal areas with significant inundation due to amplification of surge levels in embayments or due to accompanying long-wave phenomena at the most exposed coastlines of Leyte and Samar. However, localized washover fans with a storm-typical laminated stratigraphy occurred even along coasts with limited inundation due to waves overtopping or breaching coastal barriers. On a recent reef platform off Negros in the Visayan Sea, storm waves entrained coral rubble from the reef slope and formed an intertidal coral ridge several hundreds of metres long when breaking at the reef edge. As these sediments and landforms were generated by one of the strongest storms ever recorded, they not only provide a recent reference for typhoon signatures that can be used for palaeotempestological and palaeotsunami studies in the region but might also increase the general spectrum of possible cyclone deposits. Although a rather atypical example for storm deposition due to the influence of infra-gravity waves, it nevertheless provides a valuable reference for an extreme case that should be considered when discriminating between storm and tsunami deposits in general. Even for sites with low topography and high inundation levels during Supertyphoon Haiyan, the landward extent of the documented sand sheets seems significantly smaller than typical sand sheets of large tsunamis. This criterion may potentially be used to distinguish both types of events.

Environmental sensitivity of Neogoniolithon brassica-florida associated with vermetid reefs in the Mediterranean Sea

Vermetid reefs in the Mediterranean Sea are increasingly affected by both anthropogenic actions and global climate change, which are putting this coastal ecosystem at risk. The main species involved in building these reefs are two species of intertidal vermetid gastropods and the crustose calcareous alga, Neogoniolithon brassica-florida, which cements the gastropod shells and thus solidifying the reef edges. In the present study, we examined the pattern of distribution in the field and the environmental sensitivity (thermal tolerance, resilience to low pH, high light intensity and desiccation) of N. brassica-florida along the coasts of Sicily and Israel by means of chlorophyll fluorescence and total alkalinity measurements in situ and in the laboratory. Tidal regimes did not affect photosynthesis of N. brassica-florida but light intensity in the intertidal did. Sensitivity to increased light intensity was amplified by elevated temperature and reduced pH. Winter temperature above 16 °C caused a decrease in the photosynthetic performance of photo-system II. Similarly, a decrease in pH resulted in decreased maximum photosynthetic yield and electron transport rate. Calcification was significantly lower at pH 7.9 as compared with ambient (8.1) pH. In fact, dissolution at pH 7.9 at night was higher than net calcification during the day, suggesting that N. brassica-florida may not be able to contribute to reef accretion under the levels of seawater warming and ocean acidification projected by the end of this century.

Population biology and recruitment of a vulnerable sea cucumber, Stichopus herrmanni, on a protected reef

AbstractPopulations of tropical sea cucumbers, harvested for bêche‐de‐mer, are in a perilous state of conservation, yet there remains a paucity of information on the biology of many harvested species. We examined the population biology of the commercially important curryfish, Stichopus herrmanni, across 2 years on Heron Reef, a protected zone in the Great Barrier Reef (GBR) Marine Park. Stichopus herrmanni, a species recently listed as vulnerable to extinction, is a major target species for the fishery operating in the GBR. The size class distribution and density of S. herrmanni were documented for six sites across Heron Reef. There was distinct spatial variation in the size and density of S. herrmanni across sites, with no significant difference between the 2 years. The smallest individuals found were 10 cm long, some of the only juvenile S. herrmanni documented in nature. Juvenile and sub‐adult populations were found along the leeward reef edge of Heron Reef, a habitat characterized by shallow channels of sand between inter‐tidal coral reef and crustose coralline algae (CCA). Juvenile nurseries of sea cucumbers are rarely observed in nature, making this an important observation for understanding the recruitment and population biology of S. herrmanni. The presence of juveniles in the consolidated CCA habitat each year in autumn following the summer spawning period, and the absence of small individuals several months later in spring, suggests an ontogenetic migration or displacement of these individuals to adult habitat. The distribution of larger S. herrmanni suggests intra‐reef connectivity and migration into deeper lagoon areas. This study contributes to understanding the population dynamics of this vulnerable species, a consideration for fisheries management in light of increasing global harvest.

Kondisi Sumberdaya Ikan &amp; Terumbu Karang di Pulau Maratua, Kabupaten Berau, Provinsi Kalimantan Timur

This research aims to obtain describe about the condition of coral reefs and fish around maratua island. Parameter measured to support this research are the percentages of coral cover, abundance of coral fishes, and composition the types of coral fihes. The data field survey was conducted in maratua waters on July 2014. Research sites consisting of 20 station surrounding this island. Result shows that average of coral reefs in reef edge zone in good condition with a coral covered (life coral) 61 % and hard coral composition is 55 % dan soft coral 6 %. The coral reefs covered (stony coral) about 62% in depth 3-6 meters consisting of : 36 % Acropora and 26% non acropora ; and 5% others fauna ; and dead coral abour 22 %. Fish who associated with coral inhabiting waters surrounding maratua island consist of ornamental fish and reef fish consumption, which many found are Pomacentridae, Labridae, Acanthuridae, Chaetodontidae, and Nemipteridae. Result based on field observtion was found about 33 species with diversity index (H’) average 1.57 (relatively small), Uniformity index (E) average 0.3 (depressed community), and donination Index (C) average 0.42 (low).

Ability to home in small site-attached coral reef fishes.

The ability of two common, site-attached coral-reef fishes to return to their home corals after displacement was investigated in a series of field experiments at One Tree Island, southern Great Barrier Reef. The humbug Dascyllus aruanus was displaced up to 250 m, with 42% of individuals returning home, irrespective of body size, displacement, direction (up or across currents) and route complexity, while for the lemon damselfish Pomacentrus moluccensis 35% of individuals returned overall, with 33% from the greatest displacement, 100 m along a reef edge. Given that the home range of both species is <1 m(2) , over their 10+ year life span, the mechanisms and motivations for such homing ability are unclear but it may allow resilience if fishes are displaced by storm events, allowing rapid return to home corals.

Quantitative comparison of Pleistocene and Recent coral reef habitats in the northern Red Sea (El Quseir, Egypt)

Fossil reefs have the potential to provide important data for studies of climate and environmental change. This is particularly true for Pleistocene-Holocene coral reefs, which predominantly consist of communities undisturbed by anthropogenic impact and therefore provide a baseline for evaluating the status of modern reefs. We used photo transects and point-counting to quantitatively compare two Pleistocene reef terraces of two Pleistocene sites, tentatively assigned to marine isotope stage 5e, with habitats (reef flat, reef edge, reef slope at 5- and 10-m water depth) of a modern reef near El Quseir, Egypt. The modern reef exhibits a clear trend of increasing taxonomic richness and diversity from the reef flat towards the reef slope at 10-m water depth. The most abundant genera are Pocillopora, Acropora, Millepora, and massive Porites, but strong differences between individual habitats were evident. The most abundant genera in the fossil reefs are massive Porites and Dipsastraea. With regard to quantitative composition, all modern reef habitats differed significantly from each other as well as from the fossil reefs. The fossil reef composition is most similar to the modern reef slope habitat at 10-m water depth. There are two conflicting hypotheses on geodynamic processes for this area—these are tectonic uplift and tectonic stability. Considering tectonic stability, the fossil reefs would have to be interpreted as lagoonal patch reefs, for which no modern counterparts exist in the study area. However, in the case of tectonic uplift, we conclude that the fossil reefs studied were once situated at around 10-m water depth.

Interspecific variation in the spawning time of labrid fish on a fringing reef at Iriomote Island, Okinawa

The diel timing of pelagic spawning in reef fish has been discussed in the context of adaptation to local environmental conditions. However, interspecific variations in spawning time are also known to occur at a single locality. The family Labridae, composed of wrasses and parrotfishes, is one of the largest groups of fish on coral reefs. We investigated the spawning behavior and interspecific interactions of 30 species of wrasse at the same spawning site, a reef edge off Iriomote Island, Okinawa, Japan, where we previously studied 13 species of parrotfish. Six patterns in spawning time, related to time of day and high tide, were distinguished at the spawning site. Most wrasses spawned around high tide in the daytime and a few spawned at dusk only, whereas most parrotfishes spawned in the early morning, and some species exhibited intermediate (mixed) patterns. The interspecific variation in spawning time can be explained at least in part by phylogenetic constraints. Physiological constraints on spawning time are also discussed in relation to the different external cues that activate oocyte maturation.

Review of Long Wave Dynamics over Reefs and into Ports with Implication for Port Operations

This paper reviews the dynamics of infragravity (long-period) waves over reef systems and the consequences of these waves for operations in ports located behind reefs with particular attention to Western Australia. Swells which originate in the Southern Ocean generate long (infragravity) waves, which propagate to the coast. On the reef edge, the swell waves are largely dissipated, transferring energy to turbulence and heat but also in that process generating long wave energy. The remaining swell waves are dominated by the infragravity waves and propagate towards the mainland and into port basins where they cause moored ship motions with consequences for the operational downtime of the port’s operations. When contemplating solutions to mitigate the impact of the long wave problems, these may be addressed from two sides: from the load side (waves) and the strength side (mooring). The former will be discussed in this paper.

Linking sewage pollution and water quality to spatial patterns of Porites lobata growth anomalies in Puako, Hawaii

Sewage pollution threatens the health of coastal populations and ecosystems, including coral reefs. We investigated spatial patterns of sewage pollution in Puako, Hawaii using enterococci concentrations and δ15N Ulva fasciata macroalgal bioassays to assess relationships with the coral disease Porites lobata growth anomalies (PGAs). PGA severity and enterococci concentrations were high, spatially variable, and positively related. Bioassay algal δ15N showed low sewage pollution at the reef edge while high values of resident algae indicated sewage pollution nearshore. Neither δ15N metric predicted PGA measures, though bioassay δ15N was negatively related to coral cover. Furthermore, PGA prevalence was much higher than previously recorded in Hawaii and the greater Indo-Pacific, highlighting Puako as an area of concern. Although further work is needed to resolve the relationship between sewage pollution and coral cover and disease, these results implicate sewage pollution as a contributor to diminished reef health.