Distinguishing the molecular diversity, nutrient content, and energetic potential of exometabolomes produced by macroalgae and reef-building corals.

Metabolites exuded by primary producers comprise a significant fraction of marine dissolved organic matter, a poorly characterized, heterogenous mixture that dictates microbial metabolism and biogeochemical cycling. We present a foundational untargeted molecular analysis of exudates released by coral reef primary producers using liquid chromatography-tandem mass spectrometry to examine compounds produced by two coral species and three types of algae (macroalgae, turfing microalgae, and crustose coralline algae [CCA]) from Mo'orea, French Polynesia. Of 10,568 distinct ion features recovered from reef and mesocosm waters, 1,667 were exuded by producers; the majority (86%) were organism specific, reflecting a clear divide between coral and algal exometabolomes.

Extreme spatial heterogeneity in carbonate accretion potential on a Caribbean fringing reef linked to local human disturbance gradients.

The capacity of coral reefs to maintain their structurally complex frameworks and to retain the potential for vertical accretion is vitally important to the persistence of their ecological functioning and the ecosystem services they sustain. However, datasets to support detailed along-coast assessments of framework production rates and accretion potential do not presently exist. Here, we estimate, based on gross bioaccretion and bioerosion measures, the carbonate budgets and resultant estimated accretion rates (EAR) of the shallow reef zone of leeward Bonaire - between 5 and 12 m depth - at unique fine spatial resolution along this coast (115 sites).

pH Regulation and Tissue Coordination Pathways Promote Calcium Carbonate Bioerosion by Excavating Sponges.

Coral reefs are threatened by a multitude of environmental and biotic influences. Among these, excavating sponges raise particular concern since they bore into coral skeleton forming extensive cavities which lead to weakening and loss of reef structures. Sponge bioerosion is achieved by a combination of chemical dissolution and mechanical chip removal and ocean acidification has been shown to accelerate bioerosion rates.

In-situ incubation of a coral patch for community-scale assessment of metabolic and chemical processes on a reef slope.

Anthropogenic pressures threaten the health of coral reefs globally. Some of these pressures directly affect coral functioning, while others are indirect, for example by promoting the capacity of bioeroders to dissolve coral aragonite. To assess the coral reef status, it is necessary to validate community-scale measurements of metabolic and geochemical processes in the field, by determining fluxes from enclosed coral reef patches.

Spatio-temporal variation in stable isotope signatures (δC and δN) of sponges on the Saba Bank.

Sponges are ubiquitous on coral reefs, mostly long lived and therefore adaptive to changing environmental conditions. They feed on organic matter withdrawn from the passing water and they may harbor microorganisms (endosymbionts), which contribute to their nutrition. Their diets and stable isotope (SI) fractionation determine the SI signature of the sponge holobiont.

Quantification of chemical and mechanical bioerosion rates of six Caribbean excavating sponge species found on the coral reefs of Curaçao.

Excavating sponges are among the most important macro-eroders of carbonate substrates in marine systems. Their capacity to remove substantial amounts of limestone makes these animals significant players that can unbalance the reef carbonate budget of tropical coral reefs. Nevertheless, excavating sponges are currently rarely incorporated in standardized surveys and experimental work is often restricted to a few species.

Niche overlap between a cold-water coral and an associated sponge for isotopically-enriched particulate food sources.

The cold-water coral Lophelia pertusa is an ecosystem engineer that builds reef structures on the seafloor. The interaction of the reef topography with hydrodynamics is known to enhance the supply of suspended food sources to the reef communities. However, the reef framework is also a substrate for other organisms that may compete for the very same suspended food sources.

Wave-swept coralliths of Saba Bank, Dutch Caribbean.

During a recent reef coral survey at the submarine Saba Bank (Eastern Caribbean), an uncommon and diverse assemblage of unattached scleractinian corals (coralliths) was encountered, which has not been reported from the Atlantic before. Four different types of these free-living (unattached) corals were distinguished. They were observed on a relatively flat seafloor (15-20 m deep) with poor coral cover and full exposure to oceanic swell.

DOC concentrations across a depth-dependent light gradient on a Caribbean coral reef.

Photosynthates released by benthic primary producers (BPP), such as reef algae and scleractinian corals, fuel the dissolved organic carbon (DOC) production on tropical coral reefs. DOC concentrations near BPP have repeatedly been observed to be elevated compared to those in the surrounding water column. As the DOC release of BPP increases with increasing light availability, elevated DOC concentrations near them will, in part, also depend on light availability.

Effect of light and nutrient availability on the release of dissolved organic carbon (DOC) by Caribbean turf algae.

Turf algae increasingly dominate benthic communities on coral reefs. Given their abundance and high dissolved organic carbon (DOC) release rates, turf algae are considered important contributors to the DOC pool on modern reefs. The release of photosynthetically fixed carbon as DOC generally, but not always, increases with increased light availability.

Coral mucus fuels the sponge loop in warm- and cold-water coral reef ecosystems.

Shallow warm-water and deep-sea cold-water corals engineer the coral reef framework and fertilize reef communities by releasing coral mucus, a source of reef dissolved organic matter (DOM). By transforming DOM into particulate detritus, sponges play a key role in transferring the energy and nutrients in DOM to higher trophic levels on Caribbean reefs via the so-called sponge loop. Coral mucus may be a major DOM source for the sponge loop, but mucus uptake by sponges has not been demonstrated.

High dissolved organic carbon release by benthic cyanobacterial mats in a Caribbean reef ecosystem.

Benthic cyanobacterial mats (BCMs) are increasing in abundance on coral reefs worldwide. However, their impacts on biogeochemical cycling in the surrounding water and sediment are virtually unknown. By measuring chemical fluxes in benthic chambers placed over sediment covered by BCMs and sediment with BCMs removed on coral reefs in Curaçao, Southern Caribbean, we found that sediment covered by BCMs released 1.

Natural diet of coral-excavating sponges consists mainly of dissolved organic carbon (DOC).

Coral-excavating sponges are the most important bioeroders on Caribbean reefs and increase in abundance throughout the region. This increase is commonly attributed to a concomitant increase in food availability due to eutrophication and pollution. We therefore investigated the uptake of organic matter by the two coral-excavating sponges Siphonodictyon sp.

Fast detection of nutrient limitation in macroalgae and seagrass with nutrient-induced fluorescence.

Background: Rapid determination of which nutrients limit the primary production of macroalgae and seagrasses is vital for understanding the impacts of eutrophication on marine and freshwater ecosystems. However, current methods to assess nutrient limitation are often cumbersome and time consuming. For phytoplankton, a rapid method has been described based on short-term changes in chlorophyll fluorescence upon nutrient addition, also known as Nutrient-Induced Fluorescence Transients (NIFTs).

Nutrient fluxes through sponges: biology, budgets, and ecological implications.

Marine sponges are able to process a variety of carbon (C), nitrogen (N), phosphorous (P), and silicon (Si) dissolved compounds, in addition to the particulate C, N, and P obtained through regular feeding. While Si fluxes through sponges are exclusively related to the elaboration of their skeleton of biogenic silica, C, N, and P fluxes derive from a complex combination of metabolic processes that include feeding, respiration, egestion, excretion, as well as hosting of large microbial populations within the sponge body. Because of the remarkable abundance of sponges in many benthic marine communities, they have the potential to impact the availability of the compounds they take up and release, affecting the benthic-pelagic coupling and cycling rates of chemical elements that are crucial to determine growth of bacterioplankton and primary producers at the ecosystem level.

Coral cavity sponges depend on reef-derived food resources: stable isotope and fatty acid constraints.

The diet of cavity sponges on the narrow fringing reefs of Curaçao, Caribbean was studied. The origin and resources of the bulk food of these sponges, i.e.

Cell kinetics of the marine sponge Halisarca caerulea reveal rapid cell turnover and shedding.

This study reveals the peculiar in vivo cell kinetics and cell turnover of the marine sponge Halisarca caerulea under steady-state conditions. The tropical coral reef sponge shows an extremely high proliferation activity, a short cell cycle duration and massive cell shedding. Cell turnover is predominantly confined to a single cell population, i.

Organic sedimentation and macrofauna as forcing factors in marine benthic nanofagellate communities.

We investigated how benthic nanoflagellate communities in marine sediments respond to sedimentation of organic material and to the presence of macrofaunal organisms in controlled boxcosms. An input of 24 g C m(-2) resulted in a sharp increase in densities, from 93 to 477 × 10(3) flagellates cm(-3) within 11 days. At the onset, this increase was paralleled by enhanced bacterial production and bacterial numbers.