Coral Reef Fauna Research Articles

Elevated Tropical Sea Surface Temperatures During the Globally Warm Miocene Caused Heat Stress for Caribbean Coral Reefs

ABSTRACTThe warm Miocene (23.0–5.3 Ma) is considered a model case for the global climate of the near future. In view of the current coral reef crisis, studies on Miocene reefs can contribute to predictions regarding the stress resilience of today's reefs against global warming. A Late Miocene (6.2–5.5 Ma) reef coral fauna from Hispaniola Island (Caribbean) characterised by ecologically tolerant taxa was originally interpreted to reflect cool‐eutrophic waters. However, the associated planktonic foraminifer assemblage and new TEX86H–based temperature reconstructions document an oligotrophic shallow‐water environment harbouring 30–31°C. Thus, in conjunction with unusually low vertical growth rates and erratic trace element signatures of massive reef corals, the coral fauna documents critically high temperatures and a response to heat stress rather than cool upwelling. The findings demonstrate the relevance of understanding shallow‐water ecosystems from past warm periods for developing scenarios of a future, warmer world.

Reduced small-scale structural complexity on sponge-dominated areas of Indo-Pacific coral reefs

Corals provide a complex 3D framework that offers habitat to diverse coral reef fauna. However, future reefs are likely to experience reduced coral abundance. Sponges have been proposed as one potential winner on future coral reefs, but little is known of how they contribute to reef 3D structure. Given the ecological importance of structural complexity, it is critical to understand how changes in the abundance of structure-building organisms will affect the three-dimensional properties of coral reefs. To investigate the potentially important functional role of coral reef sponges as providers of structural complexity, we compared the structural complexity of coral- and sponge-dominated areas of an Indonesian coral reef, using 3D photogrammetry at a 4 m2 spatial scale. Structural complexity of 31 4 m2 quadrats was expressed as rugosity indicating reef contour complexity (R), vector dispersion indicating heterogeneity of angles between reef surfaces (1/k), and fractal dimension indicating geometrical complexity at five different spatial scales between 1 and 120 cm (D1–5). Quadrats were identified as high- or low-complexity using hierarchical clustering based on the complexity metrics. At high structural complexity, coral- and sponge-dominated quadrats were similar in terms of R and 1/k. However, smallest-scale refuge spaces (1–5 cm) were more abundant in coral-dominated quadrats, whereas larger scale refuge spaces (30–60 cm) were more abundant in sponge-dominated quadrats. Branching and massive corals contributed the most to structural complexity in coral-dominated quadrats, and barrel sponges in sponge-dominated quadrats. We show that smaller-scale refugia (1–5 cm) are reduced on sponge-dominated reefs at the spatial scale considered here (4 m2), with potential negative implications for smaller reef fauna.

δ13C and δ15N stable isotopes demonstrate seasonal changes in the food web of coral reefs at the Wuzhizhou Island of the South China sea

With a high species diversity of coral reefs, Wuzhizhou (WZZ) is a tropical marine ranch built by China. In the present study, we investigated the structure and function of coral reef food webs on WZZ in Sanya to understand how climate change and human activities affected coral reef ecosystems. Using carbon and nitrogen stable isotopes and the Bayesian mixture models, we assessed the major organic matter pathways and causes of seasonal variation in coral reef fauna and isotope values to delineate ecosystem function. Macroalgae and benthic microalgae were the primary food sources feeding this food web, while there were also some notable seasonal variations. Nutrient changes caused by temperature, upwelling, and tropical cyclones might be the primary reasons for the changes in consumer community composition and carbon or nitrogen isotopes. Seasonal environmental changes did not affect the stability of the nutrient structure of the coral reef food web on WZZ.

A coral hotspot from a hot past: The EECO and post-EECO rich reef coral fauna from Friuli (Eocene, NE Italy)

The early Paleogene “greenhouse” is the warmest geological period of the Cenozoic and a suitable source to unlock crucial information for better understanding how ecosystems such as coral reefs reacted to a climate much warmer than the present.Herein, we analyse in detail the rich museum coral collections from Friuli region (NE Italy) focusing only on the so-called reef corals, mostly colonial, and on those localities for which the age constraints are well-defined. We grouped the localities into four time-intervals within the Ypresian-Lutetian and thus within EECO (Early Eocene Climatic Optimum) and post-EECO phase, in order to assess the main changes in the following traits: 1) richness and relative abundance at the generic and species level; 2) relative abundance of growth forms; 3) colony size.By systematic revision we recognized a total of 37 genera and 103 species. During the EECO interval (late Ypresian or Cuisian), the diversity at both genus and species level was relatively low (21 genera, 37 species). An abrupt increase is then recorded in the post-EECO 1 interval (latest Ypresian), whereas a peak is reached in the earliest Lutetian (post-EECO 2) (35 genera, 90 species). These results undoubtedly show that a coral hotspot occurred in the region during the late Ypresian-early Lutetian time and highlight that corals of Friuli reacted positively immediately after the warming event of the EECO.This coral hotspot was the most diverse at global scale during the Ypresian and formed in a deltaic depositional setting, most probably in mesophotic conditions as suggested by the dominant growth forms, where rapid sediment accumulation, enhanced nutrient delivery and stressful climatic conditions reduced frame-building capacity.We finally document that corals were resilient to climate stressors and recovered before reefs which, in contrast, required much more time to achieve their buildup potential.

A Coral Hotspot from a Hot Past: The Eeco and Post-Eeco Rich Reef Coral Fauna from Friuli (Eocene, Ne Italy)

A Coral Hotspot from a Hot Past: The Eeco and Post-Eeco Rich Reef Coral Fauna from Friuli (Eocene, Ne Italy)

Vocal behavior of the endangered splendid toadfish and potential masking by anthropogenic noise

AbstractVessel‐related noise is a potential stressor for coral reef fauna. The Parque Nacional Arrecifes de Cozumel (PNAC) is a Mexican Marine Protected Area that is exposed to pervasive vessel traffic. PNAC is also the primary range of splendid toadfish (Sanopus splendidus, family Batrachoididae), an IUCN red‐listed soniferous fish for which vessel noise may represent a threat. We conducted a passive acoustic monitoring survey during summer of 2017 at Paraiso Reef in PNAC and obtained the first scientific recordings from splendid toadfish, enabling a vocal characterization of the species. We simultaneously collected data on sound levels of vessels passing near the reef. High noise levels of cruise ship and small motorboat traffic caused elevated anthropogenic sound pressure levels for up to 15 hr per day in the same bandwidth as toadfish vocalizations. A single cruise ship added up to 4 dB above nighttime ambient levels while small motorboat traffic added up to 7 dB. The overlap of toadfish vocalizations and vessel‐related noise highlights the susceptibility of splendid toadfish to acoustic masking and reduction in communication space throughout the day, warranting further study. Because acoustic communication is critical to toadfish reproductive success, noise from cruise ships and small motorboats may threaten splendid toadfish individuals or population viability.

Decadal variability in sponge abundance and biodiversity on an Indo-Pacific coral reef

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 620:63-76 (2019) - DOI: https://doi.org/10.3354/meps12968 Decadal variability in sponge abundance and biodiversity on an Indo-Pacific coral reef Alberto Rovellini1,*, Matthew R. Dunn2, Elizabeth A. Fulton3, Nicole S. Webster4,5, David J. Smith6, Jamaluddin Jompa7, Abdul Haris7, Jade Berman8, James J. Bell1 1School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand 2National Institute of Water and Atmospheric Research (NIWA), Wellington 6021, New Zealand 3CSIRO Oceans and Atmosphere, Hobart, Tasmania 7004, Australia 4Australian Institute of Marine Science, Townsville, Queensland 4810, Australia 5Australian Centre for Ecogenomics, The University of Queensland, Brisbane, Queensland 4072, Australia 6Coral Reef Research Unit, School of Biological Sciences, University of Essex, Colchester CO4 3SQ, UK 7Universitas Hasanuddin, Department of Marine Science, Makassar 90245, Indonesia 8Ulster Wildlife, Belfast, Northern Ireland BT3 9LE, UK *Corresponding author: alberto.rovellini@vuw.ac.nz ABSTRACT: Natural communities can undergo large temporal changes in abundance and species composition that may be difficult to detect without long-term ecological monitoring. Characterizing temporal variability in coral reef fauna is critical for predicting how reef ecosystems will be impacted by environmental change. Sponges are an ecologically important component of coral reefs, yet descriptions of temporal dynamics of multi-species sponge assemblages are scarce. We studied temporal changes in abundance and biodiversity of an Indonesian coral reef sponge assemblage over 13 yr (2005-2017). Mean (±SE) sponge abundance (sponge patches m-2) initially increased from 124.06 ± 8.46 to 183.73 ± 12.12 in 2005-2007 (p < 0.001), declined to 66.53 ± 10.62 in 2007-2014 (p < 0.001), and increased to 105.87 ± 15.42 in 2014-2017 (p < 0.001). These patterns in sponge abundance did not depend on water temperature. Overall, we recorded 141 sponge taxa. However, species composition showed strong temporal patterns driven by a few abundant taxa (e.g. Protosuberites sp., Sycon sp., and Pericharax sp., respectively accounting on average for ~25, 20, and 5% of total sponge abundance). Species richness increased with sponge abundance (p < 0.001), whereas evenness decreased due to dominance of some taxa in years of high sponge abundance (p = 0.002). Our study highlights that the abundance and biodiversity of Indo-Pacific sponge assemblages undergo dramatic temporal changes driven by species-specific population variability. This variability has important implications for designing monitoring programs, for interpreting experimental studies, and for understanding long-term responses of coral reefs to perturbations. KEY WORDS: Sponge assemblage · Porifera · Indo-Pacific · Population variability · Long-term monitoring · Sponge diversity Full text in pdf format Supplement 1Supplement 2 PreviousNextCite this article as: Rovellini A, Dunn MR, Fulton EA, Webster NS and others (2019) Decadal variability in sponge abundance and biodiversity on an Indo-Pacific coral reef. Mar Ecol Prog Ser 620:63-76. https://doi.org/10.3354/meps12968 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 620. Online publication date: June 18, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Bleaching-Associated Changes in the Microbiome of Large Benthic Foraminifera of the Great Barrier Reef, Australia.

Ocean warming is known to cause detrimental effects in coral reef fauna that rely on photo-symbiosis for survival. Microbial associations can facilitate the success of species across a range of environmental conditions, and play a role in the capacity of organisms to respond to climate change. In 2016, the Great Barrier Reef experienced its third mass bleaching event, with sea surface temperature rising to 1.3°C above long-term monthly summer averages. Here, I investigate the effects of ocean warming on the chlorophyll a (chl a) content and microbiome of the large benthic Foraminifera Amphistegina radiata. Samples were collected in January and April 2016, before and after the mass bleaching event. In total, 71 specimens were collected from two different depths (6- and 18-m) to investigate depth-dependant responses associated with changes in chl a and microbiome. Pigment analysis showed a significant reduction in chl a between time points in specimens collected at both depths. Reduction in pigmentation was accompanied by changes in the microbiome, and a significant interaction of depth and time was observed. Genus-level bacterial community associated with A. radiata was significantly different across depth and time. However, ocean warming affected populations at both depths to a similar extent, and resulted in change from a Betaproteobacteria-dominated assemblage in January to a more diverse bacterial community by April. Analysis of presence/absence and relative abundance of bacterial taxa revealed significant differences between time points at both depths analyzed. OTUs classified as Firmicutes, which were either absent, or present in very low relative abundances (<0.1%) across all sample groups in January, were identified in abundances as high as ∼20% in specimens collected from 18-m depth in April. Class-level shifts were observed in shallow-dwelling specimens, from high abundances of Betaproteobacteria to a high abundance and diversity of Actinobacteria. These results demonstrate the sensitivity of LBF to the effects of ocean warming, for which depth did not provide protection, and highlights the capacity of LBF to re-assemble bacterial communities after a disturbance. This study provides the first molecular-based demonstration of changes in foraminifera-associated bacterial assemblages during a bleaching event on a natural reef system.

Taxonomic richness and abundance of cryptic peracarid crustaceans in the Puerto Morelos Reef National Park, Mexico.

Background and AimsCryptic peracarids are an important component of the coral reef fauna in terms of diversity and abundance, yet they have been poorly studied. The aim of this study was to evaluate the taxonomic richness and abundance of cryptic peracarids in coral rubble in the Puerto Morelos Reef National Park, Mexico (PMRNP), and their relationship with depth.MethodsThree reef sites were selected: (1) Bonanza, (2) Bocana, and (3) Jardines. At each site six kilograms of coral rubble were collected over four sampling periods at three depths: 3 m (back-reef), 6–8 m (fore-reef), and 10–12 m (fore-reef).ResultsA total of 8,887 peracarid crustaceans belonging to 200 taxa distributed over five orders and 63 families was obtained; 70% of the taxa were identified to species and 25% to genus level. Fifty species of those collected represent new records for the Mexican Caribbean Sea. Isopoda was the most speciose order while Tanaidacea was the most abundant.DiscussionCryptic peracarid taxonomic richness and abundance were related to depth with higher values of both parameters being found in the shallow (3 m) back-reef, possibly due to a higher reef development and a greater accumulation of coral rubble produced during hurricanes. Peracarid data obtained in the present study can be used as a baseline for future monitoring programs in the PMRNP.

Exploring the genetic diversity of shallow-water Agariciidae (Cnidaria: Anthozoa) from the Saudi Arabian Red Sea

Scleractinian corals ascribed to the family Agariciidae represent an important component of Red Sea coral reef fauna, though little genetic data are currently available for this group, and existing information shows polyphyly in the examined mesophotic taxa from the Pacific Ocean. In this work, we provide a first genetic survey of Agariciidae from the Saudi Arabian Red Sea, based on a collection of shallow-water material (<30 m) from the Gulf of Aqaba to the Farasan Islands. Two molecular markers were sequenced to infer morphospecies monophyly and relationships, the intergenic region between COI and 16S rRNA from mitochondrial DNA and the ribosomal ITS1 region from nuclear DNA. A total of 20 morphospecies were identified based on classical macromorphological characters. Six, namely Gardineroseris planulata, Pavona maldivensis, Pavona clavus, Pavona decussata, Leptoseris fragilis, and Leptoseris yabei, were resolved with both DNA loci. The molecular boundaries among the remaining 14 species remain unclear. Our results further confirm that the morphology-based taxonomy of most agariciid species is in disagreement with genetics. In order to disentangle the systematics of these taxa, the inclusion of more sampling locations, additional variable loci, and a micromophological approach are likely needed. Our genetic data represent a first step towards the comparison of biodiversity and connectivity between the Red Sea and the rest of the Indo-Pacific.

Upper Triassic reef coral fauna in the Renacuo area, northern Tibet, and its implications for palaeobiogeography

Upper Triassic reef corals from the Riganpeicuo Formation in northern Tibet represent important scleractinian coral fauna that help explain the palaeobiogeography of the eastern Tethys region during the Late Triassic period. The corals were discovered in bedded limestone in patch reefs or biostromes of the Renacuo area. In this paper, 15 genera and 25 species are identified and categorized, the systematic composition of these corals and their relationships with other Triassic coral faunas are also discussed. The results show that these corals are composed of the typical elements of the western Tethys, with the following genera and species that are endemic to China: Radiophyllia cf. astylatus, Margarosmilia zogangensis and Conophyllopsis qamdoensis, and the genera Retiophyllia, Margarosmilia, Hydrasmilia, Procyclolites, Pamiroseris, Araiophyllum, Stylophyllopsis, Stylophyllum and Guembelastraea provide important links to the Tethys province. The coral fauna also highlights the connection between the Qiangtang terrane and the Songpan-Ganzi fold belt, but shows that the areas are distinct from the Himalayan terrane. It has been interpreted that the Qiangtang terrane and the Songpan-Ganzi fold belt were in the vicinity of the gradually-closed Paleo-Tethys Ocean, which resulted in the free transmigration of the benthonic organisms of these areas. On the other hand, the Himalayan terrane was separated from the Qiangtang terrane by a wide ocean–meso Tethys during the Late Triassic period, which made it impossible for the benthonic organisms on both flanks to freely migrate toward the opposite continental margins.

Report of Four Imperative Marine Macrobenthic Fauna from the Gulf of Kachchh, Gujarat, India

Report of Four Imperative Marine Macrobenthic Fauna from the Gulf of Kachchh, Gujarat, India The coral reef ecosystems world over are in danger of bleaching due to climate change and global warming. These coral reefs because of their high productivity support huge diversity of fauna. These fauna are also likely to face dangers due to coral bleaching and climate change. Hence documenting the rare fauna becomes important. Gulf of Kachchh bestowed with coral reef fauna, forms one of the four major reefs in India. Though the study of Coral reef fauna from Gulf is more than a century old, it is one of the least studied reefs in India. During our visits to Pirotan, Kalumbhar and Asaba peer Islands in the Southern Gulf of Kachchh, we encountered some interesting species; three Sea anemone i.e. Anemonia viridis (Forsskal, 1775), Aiptasia diaphana (Rapp, 1829), Heteractis crispa (Hemprich & Ehrenberg in Ehrenberg, 1834) and one Crab i.e. Actaea savignyii (Milne Edwards, 1834). The sea anemones have not been reported form Gulf of Kachchh reef whereas Crab that was reported in 1970 had not been discovered in recent studies. The present report is probably 2nd record with photographic evidence. This paper describes presence of above four species from islands in the region.

Temporal dynamics and persistence of sponge assemblages in a Central Pacific atoll lagoon

AbstractSponges are important components of coral reef fauna, although little is known of their temporal dynamics. Sponges dominate the lagoon system at Palmyra Atoll in the Central Pacific, which may not be its natural state. Here we examined the temporal variability and recruitment rates of these sponge assemblages to determine if they are stable and examined the evidence that a recent transition has occurred from a coral‐ to sponge‐dominated system. We found 24 sponge species in permanent quadrats in the lagoon between 2009 and 2011, and 11 species on our recruitment panels. The sponge assemblage composition and abundance did not vary significantly between years and appear stable. Many sponge recruits were found in both years that the panels were examined although higher rates were recorded in the second year of the study. While it seems very possible that a change to a sponge‐dominated lagoon is associated with declining environmental quality at Palmyra as a result of modifications over 70 years ago, without pre‐modification data on reef assemblage composition this remains speculative. Our observations of short‐term temporal stability in the sponge assemblages at Palmyra highlight the potential for sponge‐dominated reef states to be maintained in degraded reef environments that are seemingly unsuitable for coral survival.

Decline in abundance and health state of an Atlantic subtropical gorgonian population

Losses in coral cover have been widely reported for the Caribbean. In contrast, much less is known about the health state of the Brazilian reef fauna, which was declared as a priority for Atlantic biodiversity conservation due to its high degree of endemism. In the present study, we assessed the general health state of Phyllogorgia dilatata assemblages at the subtropical reefs of Arraial do Cabo (southeastern Brazil), where observations suggest that the abundance of this endemic gorgonian species has declined. We found that about 49% of the sampled colonies were dead, and 73% of the living colonies were affected by tissue loss. Tissue loss initially manifested as multifocal holes in the planar colonial coenenchyme and peripheral tissue retraction leaving denuded skeletal axes. In combination with other recent studies, our results raise the awareness for an increasingly threatened Southwestern Atlantic reef coral fauna.

On the origin of endemic species in the Red Sea

AbstractAimThe geological and palaeo‐climatic forces that produced the unique biodiversity in the Red Sea are a subject of vigorous debate. Here, we review evidence for and against the hypotheses that: (1) Red Sea fauna was extirpated during glacial cycles of the Pleistocene and (2) coral reef fauna found refuge within or just outside the Red Sea during low sea level stands when conditions were inhospitable.LocationRed Sea and Western Indian Ocean.MethodsWe review the literature on palaeontological, geological, biological and genetic evidence that allow us to explore competing hypotheses on the origins and maintenance of shallow‐water reef fauna in the Red Sea.ResultsPalaeontological (microfossil) evidence indicates that some areas of the central Red Sea were devoid of most plankton during low sea level stands due to hypersaline conditions caused by almost complete isolation from the Indian Ocean. However, two areas may have retained conditions adequate for survival: the Gulf of Aqaba and the southern Red Sea. In addition to isolation within the Red Sea, which separated the northern and southern faunas, a strong barrier may also operate in the region: the cold, nutrient‐rich water upwelling at the boundary of the Gulf of Aden and the Arabian Sea. Biological data are either inconclusive or support these putative barriers and refugia, but no data set, that we know of rejects them. Genetic evidence suggests that many endemic lineages diverged from their Indian Ocean counterparts long before the most recent glaciations and/or are restricted to narrow areas, especially in the northern Red Sea.Main conclusionsHigh endemism observed in the Red Sea and Gulf of Aden appears to have multiple origins. A cold, nutrient‐rich water barrier separates the Gulf of Aden from the rest of the Arabian Sea, whereas a narrow strait separates the Red Sea from the Gulf of Aden, each providing potential isolating barriers. Additional barriers may arise from environmental gradients, circulation patterns and the constriction at the mouth of the Gulf of Aqaba. Endemics that evolved within the Red Sea basin had to survive glacial cycles in relatively low salinity refugia. It therefore appears that the unique conditions in the Red Sea, in addition to those characteristics of the Arabian Peninsula region as a whole, drive the divergence of populations via a combination of isolation and selection.

Spongivory in the Wakatobi Marine National Park, Southeast Sulawesi, Indonesia

Abstract: Sponges are functionally important coral reef fauna and there is strong evidence from the Caribbean that predation has important impacts on sponge-assemblage dynamics; whether the same is true for Indo-Pacific sponges remains unknown. As a first step toward understanding the potential effects of spongivores on sponge diversity and abundance, we identified sponge predators at nine sites in Wakatobi Marine National Park, Indonesia, and conducted a short-term caging experiment to examine the effects of excluding predators on noncryptic reef sponges at this location. Nudibranchs were the most abundant invertebrate spongivores, although their low densities are likely to limit their influence on sponges. Fish were the most abundant vertebrate spongivores with 16 species from six families observed feeding on sponges. Based on their abundance and our feeding observations, the fish with the greatest potential to influence sponge assemblages in Wakatobi Marine National Park were Zanclus cornutus, Chaetodo...

Scleractinian corals (Fungiidae, Agariciidae and Euphylliidae) of Pulau Layang-Layang, Spratly Islands, with a note on Pavonamaldivensis (Gardiner, 1905).

Layang-Layang is a small island part of an oceanic atoll in the Spratly Islands off Sabah, Malaysia. As the reef coral fauna in this part of the South China Sea is poorly known, a survey was carried out in 2013 to study the species composition of the scleractinian coral families Fungiidae, Agariciidae and Euphylliidae. A total of 56 species was recorded. The addition of three previously reported coral species brings the total to 59, consisting of 32 Fungiidae, 22 Agariciidae, and five Euphylliidae. Of these, 32 species are new records for Layang-Layang, which include five rarely reported species, i.e., the fungiids Lithophyllon ranjithi, Podabacia sinai, Sandalolitha boucheti, and the agariciids Leptoseris kalayaanensis and Leptoseris troglodyta. The coral fauna of Layang-Layang is poor compared to other areas in Sabah, which may be related to its recovery from a crown-of-thorns seastar outbreak in 2010, and its low habitat diversity, which is dominated by reef slopes consisting of steep outer walls. Based on integrative molecular and morphological analyses, a Pavona variety with small and extremely thin coralla was revealed as Pavona maldivensis. Since specimens from Sabah previously identified as Pavona maldivensis were found to belong to Pavona explanulata, the affinities and distinctions of Pavona maldivensis and Pavona explanulata are discussed.

Benthic Crustacea on coral reefs: a quantitative survey

Benthic crustaceans are an important component of the coral reef fauna, yet our understanding of their ecological significance is incomplete. To determine the community structure, abundance, biomass and productivity of benthic Crustacea at Lizard Island, a mid-shelf reef on the Great Barrier Reef, Australia, we investigated 5 major microhabitats: dead coral, coral rubble, sand, epilithic algal matrix (EAM) and fine-branching live coral. Crustacean communities differed significantly among habitats, with the exception of dead coral and coral rubble. Dead coral was the most important microhabitat type in terms of crustacean abundance (7838 ± 628 ind. 100 cm-2, mean ± SE), biomass (0.75 ± 0.13 g m-2, wet weight) and estimated productivity (0.17 ± 0.043 g 100 cm-2 yr-1 ash free dry weight). These values were 2 to 3 orders of magnitude greater than those for the least important habitats (EAM and fine-branching live coral). Despite their abundance, the average crustacean body length was just 0.79 ± 0.32 mm, largely due to the dominance of harpacticoid copepods. In contrast, decapods exhibited very low abundances, but yielded the greatest biomass and productivity and were particularly abundant in dead coral and coral rubble. The results highlight the importance of small crustaceans and dead coral microhabitats as valuable contributors to the trophic structure of coral reefs.

Thinking outside the barrier: neutral and adaptive divergence in Indo-Pacific coral reef faunas

Population divergence in marine species frequently occurs where there is no conspicuous geographic feature to mark a population boundary. In the absence of a discernible barrier to gene flow, strong conclusions about the processes that drive population divergence in the ocean are often elusive. Because our knowledge of patterns far outpaces our understanding of processes, there is a need to expand hypotheses regarding population divergence in marine species. Here, I posit that certain population-level processes (range expansion, spatial diffusion constraints and metapopulation dynamics) are primary causes of spatial structuring in marine populations rather than auxiliary factors that aid divergence across an incomplete physical barrier to gene flow. In particular, I use examples from Indo-Pacific coral reef organisms to illustrate this point. In connection, spatial patterns of adaptive divergence are unlikely to be correlated with patterns of selectively neutral divergence in many cases, as the processes affecting adaptive and neutral genetic markers are different.

Contrasting responses of coral reef fauna and foraminiferal assemblages to human influence in La Parguera, Puerto Rico

Coral reef biota including stony corals, sponges, gorgonians, fish, benthic macroinvertebrates and foraminifera were surveyed in coastal waters near La Parguera, in southwestern Puerto Rico. The goal was to evaluate sensitivity of coral reef biological indicators to human disturbance. Proxies for human disturbance were measured as distance to town (DTT) and rankings of a low-level sediment contamination gradient analyzed from a previous study. Contaminant rank and DTT showed that percent mud, stony coral taxa richness, reef rugosity, and numbers of invertebrates and sponges were higher at sites closer to human disturbance, but a foraminiferal assemblage index was significantly lower at sites with higher proxies for human disturbance. Fish indicators showed no significant relationships with human activity, but associations between fish community measures and certain measures of stony corals, gorgonians and sponges were found. Contrasting responses between foraminifera and reef organisms may be due to greater exposure and sensitivity of foraminifera to sediment contaminants.