Periodic Report Summary 1 - ANIMAL FOREST HEALTH (Multiple stressor effects in the photobiology of Caribbean<br/>symbiotic octocorals and its repercussion in the population fitness and reproductive output)
The ocean transformation due to direct or indirect human interference is a fact. During the last decades, the acceleration and expansion of the so-called “ecological footprint” increase the need to develop solid tools to face the synergic problems that affect coastal and ocean ecosystems. Global threats require urgent and clear responses based on a more solid understanding of the mechanisms that affect species fitness and ecological processes. Coastal areas are the most threatened, and, paradoxically, are those which provide human communities of more services and economical, social, and health.
Our capability to understand global change phenomena and coastal communities´ responses will be essential to develop regional models which support management decisions related to environmental protection as well as sustainable fisheries, aquaculture, tourism, etc. Among the most fragile coastal ecosystems to global and local anthropogenic impact are coral reefs. Small thermal anomalies above the summer maximum temperature average (± 1 to ± 2 ºC) can induce massive coral bleaching events, and iterative eutrophication may change the biogeochemical cycles affecting the reef builders. Scleractinian and soft corals build the primary reef framework and, therefore, are fundamental for the maintenance and survival of coral reefs.
Coral reefs, as we used to know or were common decades ago, will be scarcer. Species diversity and connectivity will decrease associated with the reduction in reef rugosity and substrate, affecting the quality of life of hundreds of million persons. The main unknown is how fast these processes are affecting nowadays the fauna and flora of the reefs. Thus, an important step is to identify the most sensitive species and their role in the reef community in order to know how to mitigate such transformation. In coral reefs, hexacorals and octocorals are, with sponges, the most important contributors to the living three-dimensional structures that give complexity to the system. Their diversity and health status contribute to the correct functioning of the biogeochemical cycles, as well as to the productivity and nursing effect of the complex structures.These survival of the “animal forests” (sensu Rossi et al 2012), present all over the world with different dominance of autotrophic or heterotrophic species, depend on the surrounding environment (temperature, pH, salinity, currents, sedimentation rates, nutrients, available food, etc. In coral reefs, most of the sessile anthozoa (part of the ecosystem engineering species) are symbiotic, so the key to understand the capacity of the coral community to respond to the environmental stress, the degree of population impact (health condition) and the potential species ability to recover after the stress, requires a good understanding of the photobiology of the species and its effects on the population performance and fitness.
Most of the photobiological approaches and the analysis of the predicted global changes impact on species fitness in coral reefs have been done on hexacorals. Octocorals, in this complex panorama, have been largely neglected. Octocorals are important components of these “animal forests” including coral reefs, having a paramount role all over the world in benthic communities. In fact, octocorals are essential in the three dimensional conformation of coral reefs, their biogeochemical cycles, retention of carbon in long lived structures and the biodiversity of the system, and in some places are substituting the scleractinians as ecosystem engineer species. The analysis of their response to light and the impact of light stress in their fitness and reproductive output are completely unknown. It is therefore urgent to incorporate octocorals to the powerful photobiological approach, and to expand this approach to the entire life-history, as most experiments are short term and focus on a single life-history stage, ignoring processes such as acclimation, selection and carry-over between successive and different life-history stages.
The main objective of this project is to generate multidisciplinary tools to understand the role of the photosynthetic performance of the symbiotic algae in tropical octocorals on population fitness and potential reproduction patterns under multiple environmantal factors. The specific objectives will are 1) Make an accurate photobiological description of different species of Caribbean zooxanthellate octocorals. 2) Perform different seasonal ex-situ experiments describing the photobiology, energy storage and reproductive output of two morphologically different Ceribbean octocorals (Plexaurella nutans and Pterogorgia anceps) using temperature and acidification as the main stress factors. 3) Make a monitoring of population variability in the photobiology, energy storage, growth and reproductive characteristics along an annual cycle two chosen species. Make an accurate approach to the C translocation from Symbiodinium (algal cells) to the host and calculate the autotrophic-heterotrophic contribution to the energy input to the general C budget of the species.This effort will allow describing natural variability plasticity associated with seasonality. 4) Generation of a detailed map of the two chosen gorgonians (presence, density, population structure) in the study area with video-image treatment to generate general budgets in productivity, biogeochemical cycles and reproductive effort using the information obtained in the previous objectives, defining different scenarios and its potential impact on the coral reef diversity and structure.5) Dissemination of the results with the regular tools used in scientific projects (papers, conferences, workshops) and new tools (a scientific book, a novel and internet tools as blogs and video-blogs).
So far, the results obtained up to now show clear differences in the photosynthetic efficiency depending on the species. Morphology (spicule density, colour and size; simbiont distribution; branching pattern, S/V relationship and height/width of the colonies) but also the trophic strategy (heterotrophy-autotrophy balance) seems to play a definitive role in the adaptation of the species and its presence depending on the depth. Interestingly, the photobiological aspects are definitively less efficient compared to scleractinian or similar species in its architectural composition (e.g. hydrocorals like the fire coral), but the capability to shift to the heterotrophy in the energy input may be the one of the keys to understand its successful progress in this coral reef transition. The photobiological seasonal trends shown by Plexaurella nutans and Pterogorgia anceps follow the same pattern shown by the scleractinians, having a lower Symbiodinium and Chlrorophyll a concentration in the warm season (spring-summer) respect the slightly colder season (autumn-winter). The differences between both species is also evident in the algal concentration, the PI (photosynthesis-irradiance) curve and Q10 curves, probably related with the very different morphology of the species. The heterotrophic input, growth investment, reproductive cycle and metabolic patterns have to be analyzed to complete the picture given up to now.
The final results will help to explain coral reef transformation. If the trend is transforming the coral reefs being the calcium carbonate ecosystem engineer species (scleractinian corals) substituted by octocorals and sponges, the ecosystem services offered to the coastal human populations will be radically different. Understanding how octocorals may be more successful than scleractinians in this changing world will be essential to preview this change and give tools to the society to react during the next decades. All this information will be gather and synthesized in a single book edited by the researcher with Springer (Marine Animal Forests - The Ecology of Benthic Biodiversity Hotspots), comparing different benthic ecosystem based in suspension feeders as main builders of the complex three dimensional structure that is changing all over the world.
Our capability to understand global change phenomena and coastal communities´ responses will be essential to develop regional models which support management decisions related to environmental protection as well as sustainable fisheries, aquaculture, tourism, etc. Among the most fragile coastal ecosystems to global and local anthropogenic impact are coral reefs. Small thermal anomalies above the summer maximum temperature average (± 1 to ± 2 ºC) can induce massive coral bleaching events, and iterative eutrophication may change the biogeochemical cycles affecting the reef builders. Scleractinian and soft corals build the primary reef framework and, therefore, are fundamental for the maintenance and survival of coral reefs.
Coral reefs, as we used to know or were common decades ago, will be scarcer. Species diversity and connectivity will decrease associated with the reduction in reef rugosity and substrate, affecting the quality of life of hundreds of million persons. The main unknown is how fast these processes are affecting nowadays the fauna and flora of the reefs. Thus, an important step is to identify the most sensitive species and their role in the reef community in order to know how to mitigate such transformation. In coral reefs, hexacorals and octocorals are, with sponges, the most important contributors to the living three-dimensional structures that give complexity to the system. Their diversity and health status contribute to the correct functioning of the biogeochemical cycles, as well as to the productivity and nursing effect of the complex structures.These survival of the “animal forests” (sensu Rossi et al 2012), present all over the world with different dominance of autotrophic or heterotrophic species, depend on the surrounding environment (temperature, pH, salinity, currents, sedimentation rates, nutrients, available food, etc. In coral reefs, most of the sessile anthozoa (part of the ecosystem engineering species) are symbiotic, so the key to understand the capacity of the coral community to respond to the environmental stress, the degree of population impact (health condition) and the potential species ability to recover after the stress, requires a good understanding of the photobiology of the species and its effects on the population performance and fitness.
Most of the photobiological approaches and the analysis of the predicted global changes impact on species fitness in coral reefs have been done on hexacorals. Octocorals, in this complex panorama, have been largely neglected. Octocorals are important components of these “animal forests” including coral reefs, having a paramount role all over the world in benthic communities. In fact, octocorals are essential in the three dimensional conformation of coral reefs, their biogeochemical cycles, retention of carbon in long lived structures and the biodiversity of the system, and in some places are substituting the scleractinians as ecosystem engineer species. The analysis of their response to light and the impact of light stress in their fitness and reproductive output are completely unknown. It is therefore urgent to incorporate octocorals to the powerful photobiological approach, and to expand this approach to the entire life-history, as most experiments are short term and focus on a single life-history stage, ignoring processes such as acclimation, selection and carry-over between successive and different life-history stages.
The main objective of this project is to generate multidisciplinary tools to understand the role of the photosynthetic performance of the symbiotic algae in tropical octocorals on population fitness and potential reproduction patterns under multiple environmantal factors. The specific objectives will are 1) Make an accurate photobiological description of different species of Caribbean zooxanthellate octocorals. 2) Perform different seasonal ex-situ experiments describing the photobiology, energy storage and reproductive output of two morphologically different Ceribbean octocorals (Plexaurella nutans and Pterogorgia anceps) using temperature and acidification as the main stress factors. 3) Make a monitoring of population variability in the photobiology, energy storage, growth and reproductive characteristics along an annual cycle two chosen species. Make an accurate approach to the C translocation from Symbiodinium (algal cells) to the host and calculate the autotrophic-heterotrophic contribution to the energy input to the general C budget of the species.This effort will allow describing natural variability plasticity associated with seasonality. 4) Generation of a detailed map of the two chosen gorgonians (presence, density, population structure) in the study area with video-image treatment to generate general budgets in productivity, biogeochemical cycles and reproductive effort using the information obtained in the previous objectives, defining different scenarios and its potential impact on the coral reef diversity and structure.5) Dissemination of the results with the regular tools used in scientific projects (papers, conferences, workshops) and new tools (a scientific book, a novel and internet tools as blogs and video-blogs).
So far, the results obtained up to now show clear differences in the photosynthetic efficiency depending on the species. Morphology (spicule density, colour and size; simbiont distribution; branching pattern, S/V relationship and height/width of the colonies) but also the trophic strategy (heterotrophy-autotrophy balance) seems to play a definitive role in the adaptation of the species and its presence depending on the depth. Interestingly, the photobiological aspects are definitively less efficient compared to scleractinian or similar species in its architectural composition (e.g. hydrocorals like the fire coral), but the capability to shift to the heterotrophy in the energy input may be the one of the keys to understand its successful progress in this coral reef transition. The photobiological seasonal trends shown by Plexaurella nutans and Pterogorgia anceps follow the same pattern shown by the scleractinians, having a lower Symbiodinium and Chlrorophyll a concentration in the warm season (spring-summer) respect the slightly colder season (autumn-winter). The differences between both species is also evident in the algal concentration, the PI (photosynthesis-irradiance) curve and Q10 curves, probably related with the very different morphology of the species. The heterotrophic input, growth investment, reproductive cycle and metabolic patterns have to be analyzed to complete the picture given up to now.
The final results will help to explain coral reef transformation. If the trend is transforming the coral reefs being the calcium carbonate ecosystem engineer species (scleractinian corals) substituted by octocorals and sponges, the ecosystem services offered to the coastal human populations will be radically different. Understanding how octocorals may be more successful than scleractinians in this changing world will be essential to preview this change and give tools to the society to react during the next decades. All this information will be gather and synthesized in a single book edited by the researcher with Springer (Marine Animal Forests - The Ecology of Benthic Biodiversity Hotspots), comparing different benthic ecosystem based in suspension feeders as main builders of the complex three dimensional structure that is changing all over the world.