12.2 Abstracts of Oral Presentations
12.2.1 The Future Is Now: Anthropogenic Impacts Are Reshaping Coral Reef Ecosystems
Sebastian C.A. Ferse
1∗
1
Department of Marine Ecology, FB2 Biology/Chemistry, University of Bremen, 28359 Bremen, Germany
∗invited speaker, corresponding author: sebastian.ferse@leibniz-zmt.de
Keywords: Anthropocene, Ecosystem services, Functional ecology, Human impacts, Novel ecosystems, Reef restoration, Resilience, Social-ecological systems
At the beginning of the twenty-first century, coral reefs have become under widespread pressure from anthropogenic stressors. The recognition that humans have become a primary driver of natural processes and ecosystems has led to the characterization of the present geological epoch as the Anthropocene. The majority of reefs nowadays are within reach of human populations, and very few, if any, remain free from human impacts. This poses particular challenges for coral reef ecology. Environmental stressors are affecting reefs in non-random ways, leading to changes and potential homogenization in community composition and functioning. In many cases, there is no historical precedent for the environmental conditions and composition of coral reef ecosystems. This presentation will review the current state of coral reefs under the impact of multiple anthropogenic stressors, tracing the effects of human activities on reefs, and discuss challenges and trends of coral reef research in the Anthropocene, where reef systems are becoming increasingly homogenized as a result of non-random environmental filtering.
12.2.2 Response of Benthic Reef Communities to Manipulated In situ Eutrophication in the Central Red Sea
Denis B. Karcher
1∗
, Florian Roth
1,2
, Arjen Tilstra
1
, Yusuf El-Khaled
1
, Susana Carvalho
2
, Burton Jones
2
, Christian Wild
1
1
Marine Ecology Department, Faculty of Biology and Chemistry, University of Bremen, Bremen, Germany
2
Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
∗corresponding author: dkarcher@uni-bremen.de
Keywords: Coral reefs, Nutrients, Stable isotopes, Phase shifts, Picture analysis
Local eutrophication may heavily affect coral reef communities in the oligotrophic Red Sea, but related knowledge is scarce. As such, we investigated how a simulated 2-month eutrophication event influenced coral reef communities in an in situ experimental approach using a slow release fertilizer. Community development and elemental (C and N) composition of four major functional groups (hard corals, soft corals, turf algae, sediments) were analyzed pre- and post-nutrient manipulation using digital photographs along with elemental and stable isotope analyses. With this approach, we investigated which functional groups were best in utilizing introduced nutrients and how this is related to community development. Water samples confirmed successful in situ eutrophication with fourfold increased dissolved inorganic nitrogen (DIN) relative to background. Preliminary results (based on the photographs) show that the reef community structure was affected by eutrophication. Soft coral abundance declined in 75% of the communities where they previously had a high coverage, while turf algae increased with eutrophication in 71% of the observed communities, including all previously turf algae-dominated communities. We also occasionally observed a decreased pigmentation of hard corals and increased relative benthic coverage of macro algae (
Halimeda
sp.) under eutrophication. According to these preliminary results, turf algae and macro algae are the winners of eutrophication, while hard- and soft corals are the losers. Elemental and isotopic analyses are in progress now, and related results will be presented during YOUMARES. This analysis will provide mechanistic explanations for the observed community changes. The present study is instrumental in understanding the ecological and biogeochemical consequences of eutrophication on Red Sea coral reef communities.
12.2.3 Plasticity of Nitrogen Fixation and Denitrification of Key Reef Organisms in Response to Short-Term Eutrophication
Yusuf C. El-Khaled
1∗
, Florian Roth
2
, Denis B. Karcher
1
, Nils Rädecker
2
, Claudia Pogoreutz
2
, Arjen Tilstra
1
, Burton Jones
2
, Christian R. Voolstra
2
, Christian Wild
1
1
Marine Ecology Department, Faculty of Biology and Chemistry, University of Bremen, 28359 Bremen, Germany
2
Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), 23995 Thuwal, Saudi Arabia
∗corresponding author: yek2012@uni-bremen.de
Keywords: Nitrogen cycling, Coral reefs, Local factors of global change
An efficient uptake and recycling of nutrients is necessary to maintain high primary production in coral reefs. Particularly, the cycling of nitrogen (N) is of fundamental importance, since coral reefs are usually N-limited. However, a comprehensive understanding of the involved processes is missing to date. We thus investigated major benthic functional groups (hard corals, soft corals, biotic rock, turf algae, reef sands) of a central Red Sea coral reef. We quantified their N
2
fixation and denitrification rates under ambient and short-term (24 h) eutrophic (5 μM nitrate-enriched seawater) conditions using a combined acetylene reduction assay. Findings revealed that all functional groups were performing N
2
fixation and denitrification under both ambient control and eutrophic conditions. Under ambient conditions, N
2
fixation of turf algae was sixfold higher than that of biotic rock and tenfold higher than for all other functional groups. Denitrification was highest for biotic rock and 30% higher than for turf algae, twofold higher than for reef sands, and sixfold higher than for hard and soft corals. Under eutrophication, no significant changes relative to controls were observed for N
2
fixation, while denitrification rates were twofold higher for sands and increased by 15% for turf algae and biotic rock compared to controls. Denitrification rates for hard and soft corals under nutrient-enriched conditions were comparable to rates at ambient conditions. These findings suggest a high and rapid acclimatization and metabolic plasticity of N
2
-fixing and denitrifying microbes associated with reef sands, turf algae, and biotic rock. In contrast, responses of N cycling microbes associated with corals, which are highly adapted to nutrient-poor conditions, may only become apparent at greater time scales (e.g., days to weeks). These results may have important implications for N cycling and resilience of impacted coral reefs
12.2.4 Increased Abundance and Biodiversity of Reef Fish in a Lagoonal System Affected by Submarine Groundwater Discharge
Timo Pisternick
1,2,3∗
, Yashvin Neehaul
3
, Danishta Dumur-Neelayya
3
, Julian Döring
2
, Werner Ekau
2
, Nils Moosdorf
2
1
University of Bremen, Faculty 2 Biology/Chemistry, Bibliothekstraße 1, 28359 Bremen, Germany
2
Leibniz Centre for Tropical Marine Research (ZMT), Fahrenheitstraße 6, 28359 Bremen, Germany
3
Mauritius Oceanography Institute, Avenue des Anchois, Morcellement de Chazal, Albion, Mauritius
∗corresponding author: timo.pisternick@leibniz-zmt.de
Keywords: Submarine groundwater discharge, Nutrients, Fish abundance, Coral reef
Submarine inflow of freshwater from land into the ocean (fresh submarine groundwater discharge, FSGD) is increasingly recognized as an important source of local nutrient and pollutant influx to coastal ecosystems. Still, very little is known about the effects of FSGD on ecosystem functioning. While there is evidence of a positive link between FSGD-derived nutrients and phytoplankton abundances, further research is needed to assess the effects of FSGD on the productivity of higher trophic levels such as ichthyofaunal communities. To follow up on this relationship, we sampled two sites in a tropical coastal lagoon (Trou-aux-Biches, Mauritius) during early summer months (October–December 2017). The hydrology in the lagoon’s southern part is highly influenced by six distinct freshwater springs, whereas the lagoon’s northern part served as a control site. At each of the two sites, abiotic parameters, nutrient concentrations, as well as the dry weight of total suspended solids (TSS), composition of benthic cover and fish abundances were recorded. Water nutrient (PO
4
3-
, SiO
4
4-
, NO
3
-
, NO
2
-
, NH
3
) levels were significantly higher, whereas salinity and pH values were significantly lower in the SGD-affected southern part when compared to the northern, strictly marine part of the lagoon. TSS and coral cover were significantly higher at the SGD site while macroalgae cover was significantly higher at the control site. In addition, the SGD site exhibited significantly higher fish species richness and diversity. Also, abundances of commercially important fish species were significantly higher in the SGD-affected part of the lagoon. Our results provide first evidence of a SGD-driven positive relationship between high nutrient loadings, elevated primary production, and enhanced secondary consumer abundances in coral reef lagoons. These findings will have implications for coastal management advice and secondary consumer productivity appraisal on tropical islands.
12.2.5 Functional Redundancy and Rarity of Coral Reef Fish Among Three National Parks in Central Mexican Pacific
Diana Morales-de-Anda
1
, Amílcar Leví Cupul-Magaña
1∗
, Alma Paola Rodríguez-Troncoso
1
, Fabián Rodríguez-Zaragoza
2
, Consuelo Aguilar-Betancourt
3
, Gaspar González-Sansón
3
1
Departamento de Ciencias Biológicas CUCosta Universidad de Guadalajara, 48280, Puerto Vallarta, México
2
Departamento de Ecología CUCBA Universidad de Guadalajara, 45110, Zapopan, México
3
Departamento de Estudios para el Desarrollo Sustentable de la Zona Costera CUCSur Universidad de Guadalajara, 48980, Cihuatlán, México
∗corresponding author: amilcar.cupul@gmail.com
Keywords: Fish assemblages, Functional traits, Functional vulnerability, Functional entities
Reef fish from the Central Mexican Pacific (CMP) represent an interesting scenario to understand how sites with lower diversity respond to multiple stressors (high dynamism, marked hydroclimatic periodicity, overall low coral cover, and anthropogenic pressure) and are still able to maintain ecosystem processes and functions. Therefore, we evaluated the functional component of reef fish communities and their spatial variation across three national parks in CMP (Islas Marietas, Isla Isabel, and Isla Cleofas). Our aim was to identify island’s functional redundancy and vulnerability, evaluate rarity of species and functional entities (FEs), and analyze changes in fish functional community composition. We used data from underwater visual census; fish species and interval length records were used to create FEs matrix with species data and fish traits (length, aggregation, diet, mobility, position in water column, and activity period). To evaluate functional component, we performed functional indices (redundancy, FR; vulnerability, FV; and rarity) and evaluated differences in indices and FEs composition among islands. We found 80 species distributed in 54 FEs; FR was low for all islands (less than 1.5 species/FE) being significantly lower for Islas Marietas, the recently popularized island closest to shore. On the other hand, FV was markedly high for all islands (76% of FEs represented by one species). Across islands, rarity was common with 75% of rare FEs and 85% of rare species in FEs; meanwhile 7–16% of species and FEs had only one individual in all islands. Overall, our study shows that despite the low redundancy present across the three islands, we also found a large number of functions among reef fish; however, many functions remained vulnerable and rare. Each island had specific FEs and marked dissimilarities in FEs composition; these characteristics make each island unique and highlight the importance of special protection for the three islands, particularly those with constant anthropogenic pressure.
12.2.6 Population and Reproductive Biology Aspects of the Vinegar Crab
Episesarma mederi
H. Milne Edwards, 1853 (Decapoda, Sesarmidae) from a Tropical Mangrove Area in Capiz, Philippines
Jerry Ian Leonida
1∗
, Juliana Baylon
2
, Shaira Ballon
2
, Elilyn Farrah Belle Barredo
2
, Ma. Shirley Golez
2
1
Institute of Marine Fisheries and Oceanology, College of Fisheries and Ocean Sciences, University of the Philippines Visayas, Miagao, Iloilo 5023, Philippines
2
Division of Biological Sciences College of Arts and Sciences, University of the Philippines Visayas, Miagao, Iloilo 5023, Philippines
∗corresponding author: jlleonida@up.edu.ph
Keywords: Mangrove crab, Sesarmid, Ovarian development, Histology, Oocyte maturation, Spawning period
Vinegar crabs of the
Episesarma
genus are among the dominant crab groups in estuarine and mangrove areas in the tropics. These burrow-dwelling crabs play vital roles in the nutrient cycling and substrate biochemistry of their inhabited ecosystems.
Episesarma mederi
is a traditional and a growing fishery resource in the Philippines that may have aquaculture potential. However, a constraint in managing this crab species is the lacking knowledge about its reproductive biology. This holds true for the other members of the genus. This study was the first to analyze aspects of the population structure and gonadal maturation stages of
E. mederi
in Capiz, Philippines (11° 26’ 34” N, 122° 55’ 23” E). Samples were randomly collected by hand during low tide periods every first week of the month from February 2016 to January 2017. In the laboratory, morphometric analysis and sexual determination were performed. Staging of gonadal development was established by complementing morphological features (i.e., color, volume) with histological analysis (i.e., cell type, size). A total of 448 crabs (184 males, 264 females, 105 ovigerous females) were collected. Males were fewer but larger and heavier than females. Five stages of ovarian development were identified: immature, developing, maturing, mature (two substages – early mature and late mature), and spent. Among ovigerous females, the smallest size has 29 mm carapace width (CW), and the size class range of 30–34 mm CW had the highest prevalence of spawning samples. Monthly ovarian development indicates a continuous breeding cycle. However, two periods of higher reproductive activity were identified in females, which coincided with the onset and culmination of the rainy season in the Philippines. This suggests that
E. mederi
exhibits a seasonal-continuous reproduction strategy. Accordingly, these reproductive features must be accounted in management strategies to prevent the overexploitation of the wild stocks of this species.
12.2.7 The Overlooked Contribution to Organic Matter Sequestration in Mangrove Forests:
Acrostichum aureum
, an Understory Fern
Michael K. Agyekum
1∗
, Martin Zimmer
1
, José M. Riascos
2
1
Leibniz Centre for Marine Tropical Research (ZMT), Bremen
2
Estuaries & Mangroves Research group, Universidad del Valle, Cali, Colombia
∗corresponding author: michaelk@uni-bremen.de
Keywords: Mangrove fern, Organic matter content, Organic carbon, Macrofauna, Sediment characteristics, Detritivore
Understory plants have been long assumed an odd exception in mangrove forest; thus we ignore the role that some common floristic elements may play. Here we studied the cosmopolitan fern
Acrostichum aureum
in a neotropical mangrove. Experimental manipulations of the fern litter fall (litter exclusion, the potential effect of the net, control and fern areas) were set up to test the hypothesis that fern-derived organic matter influences the species composition of the fauna and sediment characteristics in the mangrove forest of Bahía Málaga, Colombia. Sediment samples were collected in October 2016 and March 2017 from the experimental plots and analyzed for pH, total dissolved solids, carbon-nitrogen ratio, organic matter content, and organic carbon. Macrofauna species were sampled after 5 months of experimental manipulations of the sediment. The results indicated no significant differences for the macrofauna species composition in either the stations or treatments. In contrast, there was a significant difference in the sediment characteristics among treatments. The results suggest the magnitude of change in organic matter and organic carbon is small yet quite consistent in this study to support the hypothesis that the fern-derived organic matter is important in influencing the sediment characteristics. Therefore, more time is required for the integration of organic matter in the sediment of the mangrove forest.
12.2.8 Lipidomic Characterization of Microbial Communities of the Extremely Acidic Shallow Water Hydrothermal System of Kueishantao (Taiwan)
R.F. Aepfler
1∗
, M. Elvert
1
, K.U. Hinrichs
1
, Y. Lin
2
, S.I. Bühring
1
1
University of Bremen, MARUM, Postbox 330 440, Bremen, Germany
2
National Sun Yat-Sen University, Kaohsiung, Taiwan
∗corresponding author: rebecca.aepfler@uni-bremen.de
Keywords: Extreme environment, Polar lipid-derived fatty acids, Intact polar lipids, Campylobacteria, Reverse tricarboxylic acid cycle
The Kueishantao shallow water hydrothermal vent system located off Taiwan’s NE coast (121°57’ E, 24°50’ N) is characterized by world-record low pH conditions (pH < 1) and fluid temperatures of up to 116°C. High CO
2
discharge provides a natural laboratory to study the effect of ocean acidification on microbial communities. In 2015, sediment cores and hydrothermal fluids were collected from a hot (116°C, pH = 2.88) and a warm temperature vent (58°C, pH = 4.51), in order to study the lipidome of the microbial community. The polar lipid-derived fatty acid (PLFA) pattern of both vent sediments showed dominating C
16:1ω7c
, C
18:1ω9
, and C
18:1ω7c
, revealing enriched δ
13
C-values of -12‰, -19‰, and -12‰ in the warm sediments and of -10‰, -14‰, and -15‰ in the hot sediments, respectively. PLFAs in the warm vent fluid likewise showed C
16:1ω7c
and C
18:1ω7c
being enriched in 13C with δ
13
C values of -13‰ and -8‰, respectively. These positive δ
13
C values are best explained by the activity of campylobacteria, which have been identified metagenomically at the study site. These bacteria possess the reverse tricarboxylic acid cycle for carbon fixation, a metabolic pathway that discriminates less against
13
C than the Calvin-Benson-Bassham cycle. Complementing analyses of intact polar lipids (IPLs) revealed the presence of sphingolipids and hydroxylated ornithine lipids in the warm vent sediments, with the latter being assumed to increase the stress tolerance toward high temperatures and acidic pH values. That way, bacteria are able to adjust their membrane properties by modifying already existing membrane lipids without the need to synthesize new lipids. Sphingolipids on the other hand, might reduce the membrane permeability through strong intramolecular hydrogen bonding, counterbalancing configurations that lead to a stress-induced fluidization of the membrane.
12.2.9 Patterns and Drivers of Coral Reef Resilience at Aldabra Atoll, Seychelles
Anna Koester
1∗
, April J. Burt
2
, Nancy Bunbury
3
, Amanda K. Ford
4
, Valentina Migani
5
, Cheryl Sanchez
3
, Frauke Fleischer-Dogley
3
, Christian Wild
1
1
Marine Ecology Department, Faculty of Biology & Chemistry, University of Bremen, Germany
2
The Queens College, High Street, Oxford, OX1 4AW, United Kingdom
3
Seychelles Islands Foundation, Postbox 853, Mont Fleuri, Victoria, Mahé, Seychelles
4
Leibniz Center for Tropical Marine Research (ZMT), Fahrenheitstrasse 6, 28359 Bremen, Germany
5
Institute for Ecology, Faculty of Biology & Chemistry, University of Bremen, Germany
∗corresponding author: anna.koester@uni-bremen.de
Keywords: Coral bleaching, Climate change, Recovery, Marine monitoring, Remote
The recent global coral bleaching event in 2016 caused mass mortality of corals worldwide and affected even the best protected and most remote reefs. This challenges the common notion that reefs far removed from local human impacts are more resilient to the effects of climate change. To understand reef resilience under the exclusive influence of global impacts, we study the susceptibility to, and recovery since, the 2016 global bleaching event at Aldabra Atoll, a UNESCO World Heritage site in the Western Indian Ocean. We combine the annual monitoring of benthic reef assemblages with additional observations of coral larvae settlement, sedimentary oxygen consumption, and turf algae height to assess post-bleaching trajectories (i.e., stability/recovery/degradation) and how these differ on an atoll-wide scale. Aldabra lost 50% of its hard corals during the 2016 bleaching event and experienced reductions of taxonomic and morphological diversity within the benthic assemblages. Initial results of recent field work (December 2017–March 2018) reveal differing post-bleaching trajectories, with the two most easterly reefs indicating further reductions in hard coral cover and increasing cover of calcifying macroalgae (
Halimeda
spp.). At the remaining ten sites, hard coral cover remained stable or increased, while turf algae cover decreased to pre-bleaching levels. Additional observations indicate atoll-wide similarities in turf algae height and sedimentary oxygen consumption, but marked differences in the density of settled coral larvae, which was substantially higher within Aldabra’s lagoon. These results suggest that prevailing environmental conditions at the individual reefs around the atoll are important drivers of reef resilience. Further analysis is now needed to examine the atoll-wide shifts in benthic and coral community composition in response to various biological and environmental variables. The results of this study will contribute to our understanding of the natural drivers of coral reef resilience, thereby aiding the identification of priority areas for conservation.
12.2.10 Recovery Capacity and Physiology of Kimberley Corals After Unprecedented Bleaching
E. Maria U. Jung
1,2∗
, Malcolm T. McCulloch
1,3
, Verena Schoepf
1,3
1
ARC Centre of Excellence for Coral Reef Studies, UWA Oceans Institute and School of Earth Sciences, The University of Western Australia, Perth, WA, Australia
2
Department of Biology and Chemistry, University of Bremen, Bremen, Germany
3
The Western Australian Marine Science Institution, Perth, WA, Australia
∗corresponding author: emu.jung@uni-bremen.de
Keywords: Heat tolerance, Energy reserves, Symbiont dynamics, Extreme reef environments
Ocean warming is one of the major threats to coral reefs today and leads to global mass bleaching events of increasing severity and frequency. In 2016, a marine heatwave caused unprecedented bleaching in the extreme macrotidal Kimberley region in northwest Australia. We report both recovery and the extent of coral mortality six months after the peak bleaching as well as the physiological mechanisms underlying both heat tolerance and recovery capacity of these corals. Coral cover and health from both heat-tolerant intertidal (IT) and heat-sensitive subtidal (ST) environments were investigated via photo-quadrat analyses. Samples of
Acropora aspera
were collected from both environments during and after the bleaching event and assessed for symbiont density, chlorophyll
a
, and energy reserves (lipid, protein, and carbohydrate). Despite being exposed to similar heat stress during peak bleaching (~4.6 degree heating weeks), bleaching was more severe in the subtidal than intertidal. Furthermore, ST corals had a much lower recovery capacity with 71% mortality, whereas 91% of IT corals were visibly healthy after 6 months of recovery. Analyses of symbiont dynamics confirmed visually observed differences in bleaching susceptibility and severity. Only bleached IT corals catabolized energy reserves during bleaching, demonstrating that maintaining energy reserves during bleaching cannot guarantee survival. This suggests that other factors influenced the low recovery capacity of ST corals. However, the fast recovery of IT corals gives hope for reef habitats that suffered from extensive mortality during the 2016 bleaching event in the Kimberley. These findings demonstrate that corals from extreme temperature environments can provide important insights into the mechanisms underlying coral heat tolerance.
12.2.11 Neuroactive Compounds Induce Larval Settlement in the Scleractinian Coral
Leptastrea purpurea
Mareen Moeller
1∗
, Samuel Nietzer
1
, Peter J. Schupp
1
1
Carl-von-Ossietzky Universität Oldenburg, ICBM, Environmental Biochemistry, Schleusenstrasse 1, 26382 Wilhelmshaven, Germany
∗corresponding author: mareen.moeller@uni-oldenburg.de
Keywords: Recruitment, Settlement, Metamorphosis, Brooder, Cnidarian
Settlement of pelagic coral larvae is commonly induced by chemical cues that originate from biofilms. These natural settlement cues initiate signal pathways leading to attachment and metamorphosis of the coral larva. In order to investigate the settlement process and natural inducers, it is necessary to gain a better understanding of these signal pathways. At present, the pathways and neurotransmitters involved in this signal transduction are still widely unknown. In this study, we exposed larvae of the brooding coral
Leptastrea purpurea
to five neuroactive compounds known to be present in cnidarians, and K+ Ions. All compounds were applied at different dilutions and settlement behavior of the larvae was documented over 48 h. Dopamine, glutamic acid, and epinephrine significantly induced settlement in the coral larvae. Exposure to dopamine resulted in 58% in the strongest metamorphosis response. Serotonin, L-DOPA, and K+ ions did not have an influence on settlement behavior in our experiments. Exposing larvae to settlement-inducing neurotransmitters and thus bypassing the initial induction could be utilized in coral aquaculture. The active neurotransmitters could also be used to study the settlement process in greater detail.
12.2.12 Coral Larvae Every Day:
Leptastrea purpurea
, a Brooding Species That Could Accelerate Coral Research
Samuel Nietzer
1∗
, Mareen Moeller
1
, Makoto Kitamura
2
, Peter J. Schupp
1
1
Carl-von-Ossietzky Universität Oldenburg, ICBM Terramare, Schleusenstrasse 1,
26382 Wilhelmshaven, Germany
2
Okinawa Environment Science Centre, Urasoe, Okinawa 901-2111, Japan
∗corresponding author: samuel.nietzer@uni-oldenburg.de
Keywords: Coral reproduction, Brooding, Recruitment, Settlement cues, Faviid
Sexually produced larvae are used in various fields of coral research. Because the vast majority of scleractinians reproduce only on one or few occasions per year through simultaneous release of gametes, and ex situ spawning induction is still very hard to achieve, high efforts are required to obtain planula larvae. Brooding corals have been used to harvest planulae, but their larvae oftentimes differ in various traits, e.g., settlement behavior, from most spawning corals. Other cnidarians, such as
Aiptasia
spp., have been substituting scleractinians in many aspects of coral research. However, organisms such as
Aiptasia
differ strongly from scleractinians limiting the transferability of obtained results. This study examines the potential of
Leptastrea purpurea
as a reliable source of larvae for coral research. Larval output throughout the year as well as settlement behavior of planulae was investigated. Our results show that
L. purpurea
releases larvae on a daily basis, thus allowing permanent access to planula larvae. Larval settlement is induced by the same and similar cues as in many spawning species which increases the transferability of conclusions. We discuss the aptitude of
L. purpurea
for research on scleractinian physiology, ecology, and larval settlement and conclude that
L. purpurea
is a well-suited organism to accelerate progress in many fields of coral research.
12.2.13 Development of a Coral Reef Resilience Index (CRRI): A Spatial Planning Tool for Managers and Decision-Makers Applicable in Caribbean Coral Reef Ecosystems
Sonia Barba-Herrera
1,2,3,4∗
, Edwin Hernández-Delgado
2,3,4
1
Department of Biological Sciences, School of Sciences, University of Málaga, Av. de Cervantes, 2, 29016 Málaga, España
2
Department of Environmental Sciences, University of Puerto Rico, Av. Dr. José N. Gándara, San Juan, 00931, Puerto Rico
3
CATEC: Centre of Applied Tropical Ecology and Conservation, Av. Dr. José N. Gándara, San Juan, 00931, Puerto Rico
4
SAM: Sociedad Ambiente Marino, Marine Environment Society, San Juan, 00931, Puerto Rico
∗corresponding author: sonia5bh@hotmail.com
Keywords: Ecosystem health, Coral reefs, Marine management, Marine biodiversity, Tropical ecosystems
Coral reefs worldwide are in severe decline due to a combination of local human stressors, and large-scale climatic stressors, such as sea surface warming. However, there is often a general lack of information regarding the status and resilience of coral reef ecosystems. Timely information is critical to implement sustainable management measures. The main objective of this project was to develop a Coral Reef Resilience Index (CRRI) and provide a GIS-coupled decision-making tool for reef managers applicable for Caribbean coral reef ecosystems. The CRRI is based in a 5-point scale parameterized from quantitative documentation regarding benthic assemblages. Separate sub-indices such as the Coral Index, the Threatened Species Index, and the Algal Index provide specific information regarding targeted benthic components. This case study was based on assessments conducted in 2014 on 11 reef sites located across 3 geographic zones and 3 depth zones along the southwestern shelf of the island of Puerto Rico, Caribbean Sea. Results showed a significant spatial and bathymetric gradient in the distribution of CRRI values that indicated higher degradation of inshore coral reefs, in comparison to mid-shelf and offshore sites. Mean global CRRI within inshore reefs ranged from 2.78 to 2.87, ranking them as fair. Mean CRRI within mid-shelf localities ranged from 2.97 to 3.17, ranking them between fair and good. CRRI ranged from 3.07 to 3.16 within outer shelf localities, ranking them as good. The coral and algal indices showed declining trends toward inshore reefs, and the threatened corals index showed a general cross-shelf poor state, with the exception of two localities. CRRI has provided an important, solid management and decision-making tool for Caribbean coral reefs. A future re-evaluation is recommended to be conducted to determine the effects of the 2017 Hurricane María and compare CRRI in a multi-temporal scale.
12.2.14 Factors Driving Benthic Community Change on the Mexican Caribbean Over the Last 12 Years (2005–2016)
Xochitl E. Elías Ilosvay
1∗
, Ameris I. Contreras-Silva
1
, Lorenzo Alvarez-Filip
2
, Christian Wild
1
1
Marine Ecology Group, Faculty of Biology and Chemistry, University of Bremen, Leobener Straße UFT, 28359, Bremen, Germany
2
Biodiversity and Reef Conservation Laboratory, Unidad Académica de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Puerto Morelos, México
∗corresponding author: xoel@uni-bremen.de
Keywords: Coral reef, Drivers of change, Meta-analysis
The Mexican Caribbean experiences community changes in coral reefs, but knowledge on potential global and/or local drivers of these changes is scarce. This study thus describes through random effects meta-analysis, the relative effects of sea surface temperature (SST), chlorophyll water concentration, coastal human population development, reef distance to shore, water depth, and geographical latitude on the hard coral and algae cover in 50 reef sites along the coast of Quintana Roo, Mexico. Findings revealed that against our expectations, there was a significant increase of both hard coral cover (by ca. 5 %) and algae cover (by ca. 14 %, i.e., almost three times the increase of corals) over the last 12 years. These results on the one hand reflect partial coral recovery after the 2005 Caribbean mass coral bleaching event but on the other hand rapid invasion of algae in local reefs. Surprisingly, none of the selected factors correlated positively or negatively with changes in coral cover. However, latitude and human population density exhibited significant effects on reef algae cover increase. Against our expectation, there was more algae cover increase in the southern part of the Yucatán Peninsula coast where population density was lower, but recent major coastal and tourism development took place. This study is important for monitoring and management of coral reefs in the Caribbean, because by using simple methods and existing data it gives indications for the drivers of change in reef communities.