September 9-10, 2011
Water Quality: The Importance of Multispecies Numerical Modeling of Plankton Environments
Dan Roelke (Texas A&M University)
Abstract
Water quality is portrayed in many ways. These commonly include characterizations of biodiversity, harmful algal blooms, and hypoxia. Less common are characterizations of the underwater light field, or the spectral quality of light, which is essential for the health of ecosystems in oligotrophic waters, such as coral reefs. Phytoplankton succession and assemblage composition influences all of these, and to better understand succession and assemblage effects, approaches that embrace multispecies interactions are needed. Here, multispecies numerical modeling approaches are presented that illustrate how such models can be used to better understand factors that influence biodiversity, harmful algal blooms, and hypoxia. For each of these, the nature of inflows strongly influences model behaviors. For example, biodiversity can collapse when mixing is excessive, while episodic inflows can serve to buffer this effect. Hydraulic flushing events, if of large enough magnitude, can circumvent harmful algal blooms altogether. And inflows to coastal environments can increase stratification, exacerbating hypoxia even when nutrient loading is reduced. All of these studies require the use of multispecies models to arrive at their findings. Characterizing the underwater light field is no exception. Because phytoplankton taxa have varied cellular photopigment content, they color the water differently depending on which taxa dominates the assemblage at any given time. Taxon dominance is sensitive to anthropogenic activities, such as development in the coastal zone. Thus, alterations within watersheds can influence phytoplankton assemblage composition, the spectral quality of light, and the health of oligotrophic ecosystems.
Biogeography of Bacteria in Surface Waters of the Red Sea
Ulrich Stingl (King Abdullah University of Science and Technology)
Abstract
The Red Sea is a unique marine ecosystem with contrasting gradients of temperature and salinity along its north to south axis. It is an extremely oligotrophic environment that is characterized by perpetual year-round water column stratification, high annual solar irradiation, and negligible riverine and precipitation inputs. In this study, we investigated whether the contemporary environmental conditions shape community assemblages by pyrosequencing 16S rRNA genes of bacteria in surface water samples collected from the northeastern half of this water body. A combined total of 1,855 operational taxonomic units (OTUs) were recovered in the free-living and particle-attached fractions. Here, a few major OTUs affiliated with Cyanobacteria and Proteobacteria accounted for ~93% of all sequences whereas a tail of “rare” OTUs represented most of the diversity. OTUs allied to Surface 1a/b SAR11 clades and Prochlorococcu -related to the high light-adapted (HL2) ecotype were the most widespread and predominant sequence types. Interestingly, the frequency of taxa that are typically found in the upper mesopelagic zone was significantly elevated in the northern transects compared to those in the central. Although temperature was the best predictor of species richness across all major lineages, both spatial distance and environmental variables strongly correlated with genetic distances. Our results suggest that the bacterial diversity of the Red Sea is as high as in other tropical seas and provide evidence for fundamental differences in the biogeography of pelagic communities between the northern and central regions.
Coral Reef Ecosystems Monitoring – An Integrative Approach to Modeling Reefs in a Physical, Chemical, and Biological Context
Christian R. Voolstra (King Abdullah University of Science and Technology)
Abstract
We are in the process of setting up a survey and monitoring program for selected coral reefs near KAUST with the aim of understanding the physical, chemical, and biological interactions in Red Sea Coral Reef ecosystems in a spatial and temporal context. We strategize to collect continuous measures for temperature, salinity, pH, nutrients, turbidity, light intensity, ocean currents, tides, waves, etc. using the most modern instrumentation and analytical methods. Seasonal tile deployment aims to investigate year-round algal primary production, biofilm conditions, bioerosion and bioaccretion as well as reproduction rates of scleractinian corals and other calcifying benthic organisms. We will further incorporate detailed biannual (summer vs winter) characterizations of reef structure and coral metabolism by transect work, tissue sampling, and meta-community analyses.
In a preliminary reef survey we compared ocean- and land-facing sides of off-, mid- and near-shore reefs in an area covering over 1,200 km2. Our results indicate distinct changes in community structure with distance to shore as well as strong differences between exposed and sheltered reef sides. We have therefore chosen representative reefs from the different habitats in order to cover the widest possible variety of community diversity for establishing permanent monitoring stations.
In summary, we propose a multi-pronged approach: 1) field work-based collection of samples and monitoring of key environmental and ecological factors, 2) phylogenetic and metagenomic profiling of the collected samples, 3) computational biology-mediated multi-dimensional data integration and analysis, and 4) developing a comprehensive reef model for forecasting the influence of physical and biological changes as introduced by climate change and other anthropogenic impacts.
This has been a joint collaboration with Conny Roder, King Abdullah University of Science and Technology.
An Overview of How Land and Water Management Affect the Ecological Integrity of Oceans
Brad Wilcox (Texas A&M University)
Abstract
In this talk, I will provide a brief review of how rivers and water ways have changed during the last 50 years in particular and describe how these changes may affect the ecological integrity of oceans. We now understand that there is a particularly close coupling of the quality and quantity of waters in rivers and the ecological integrity of our oceans. Changes to rivers have occurred through direct actions such as dam construction and river regulation as well as input of municipal waste directly into rivers. Up to 90 percent of the earths major rivers are highly regulated and their flow patterns have been considerably altered. These changes may lead to rather complex and poorly understood changes to ocean currents. Other types of changes are a result of indirect actions such as changing land use (expanding agriculture, urbanization). These changes lead to eutrophication of fresh water bodies on land as well as coastal waters.
Modeling Complex Fish Life History to Understand the Effects of Fishing Pressures
Masami Fujiwara (Texas A&M University)
Abstract
Organisms exhibit a wide range of life history strategies. For example, some have early maturation while others delay maturation, some adopt semelparous reproductive strategies while others are iteroparous, and some are long-lived and others short-lived. Such demographic biodiversity is likely to have profound effects on population dynamics. As fisheries management worldwide faces the challenge of managing fish stocks that encompass broad demographic biodiversity, there is great interest in investigating the relationship between life history traits and population dynamics. I demonstrate that there are marked differences in the sustainable yield among species with different life history strategies. In particular, semelparous fish can produce very high sustainable yields, near or above 50% of the carrying capacity, whereas long-lived iteroparous fish can produce very low sustainable yields, which are often much less than 10% of the carrying capacity. The difference is not because of different levels of sustainable fishing mortality rate, but because of difference in the sensitivity of the equilibrium density to fishing mortality. In addition, the resilience of fish stocks tends to be reduced with increased fishing mortality. This means that changes in population density in response to natural or anthropogenic perturbations will last longer at higher fishing mortality rates. Finally, I show the population dynamics of hermaphroditic fish. One of the advantages of hermaphroditic life history strategies is in their ability to adjust sex ratio. Therefore, a ratio-dependent sex-change rate was incorporated into the model. It is demonstrated that, when this rate strongly depends on the sex-ratio, the population can exhibit chaotic dynamics
The Global Marine Species Assessment: Laying the Foundation for Marine Conservation
Beth Polidoro (International Union for Conservation of Nature)
Abstract
The presence of threatened species often forms the basis for marine conservation priorities, including the designation of critical habitat, no-take zones, the creation of new or improved MPAs, or to support policies that regulate resource extraction or coastal development. The IUCN Species Programme-Global Marine Species Assessment (GMSA) is systematically assessing over 20,000 marine species in complete taxonomic and regional groups for inclusion on the IUCN Red List of Threatened Species. Priority groups include all of the world’s marine vertebrates; primary habitat producers such as corals, seagrasses and mangroves; and selected invertebrate families of crustaceans, echinoderms, and molluscs. To date, more than 10,000 species have been assessed, and already approximately 15% are in threatened categories. Resulting species data and analyses generated by the GMSA are used in a wide range of regional and international initiatives to identify marine species and geographic areas in need of immediate conservation action.
This has been a joint work with Kent Carpenter, Heather Harwell, Jonnell Sanciangco, and Mia Comeros-Raynal.
An Overview of KAUST’s Reef Ecology Projects
Michael Berumen (King Abdullah University of Science and Technology)
Abstract
Our lab is engaged in several interdisciplinary projects addressing numerous aspects of coral reef ecology. This overview aims to familiarize workshop attendees with our ongoing work, primarily to identify areas of potential collaboration. The projects are based at a range of field sites around the world, although we certainly try to take advantage of KAUST’s Red Sea location. One of the primary unifying themes of these projects is movement ecology, with studies ranging from larval fish dispersal to whale shark movements. These projects utilize several methodologies, including acoustic and satellite tags, genetic parentage analysis, otolith chemistry, and photo identification. The findings of these projects are immediately relevant to management and will be used to guide the design and implementation of marine protected areas (MPAs) within Saudi Arabia and other study areas.
Other major research themes include life history studies, nutritional ecology, and evolutionary ecology and biology. Life history studies are fundamental for conservation and management of any species, and we target knowledge gaps such as growth rates, age or size of reproductive maturity, population demographics, and other characters. Our nutritional ecology studies are primarily focused on corallivores and understanding the role of corals in reef system food webs. Understanding these food webs will help to more accurately predict how corallivores and other reef fishes will be affected by climate change. Evolutionary studies are primarily focused on fishes endemic to the Red Sea and their relationships to sister species in other oceans.
The Trojan Y-Chromosome Model for Eradication of an Invasive Species
Jay Walton (Texas A&M University)
Abstract
This talk describes recent analytical and numerical results for a mathematical model of a Trojan Y-chromosome strategy for eradicating an invasive species. The model applies to species who reproduce via an X-Y chromosome system and for which genetic engineering can produce a feminized “super-male” (YY-genotype) which when artificially introduced into the invasive population causes the steady decline of wild-type females leading to the gradual die-off of the invader with minimal negative impact upon native species. Both deterministic and stochastic spatial models are considered.
This has been a joint collaboration with Rana Parshad, King Abdullah University of Science and Technology.
Abrupt Warming of the Red Sea
Dionysios RaitsosExarchopoulus (King Abdullah University of Science and Technology)
Abstract
Coral reef ecosystems, often referred to as “marine rainforests,” concentrate the most diverse life in the oceans. Red Sea reef dwellers are adapted in a very warm environment, fact that makes them vulnerable to further and rapid warming. The detection and understanding of abrupt temperature changes is an important task, as ecosystems have more chances to adapt in a slowly rather than in a rapid changing environment. Using satellite derived sea surface and ground based air temperatures, it is shown that the Red Sea is going through an intense warming initiated in the mid 90s, with evidence for an abrupt increase after 1994 (0.7°C difference pre and post the shift). The air temperature is found to be a key parameter that influences the Red Sea marine temperature. The comparisons with Northern Hemisphere temperatures revealed that the observed warming is part of global climate change trends. The hitherto results also raise additional questions regarding other broader climatic impacts over the area.
This is a joint work with I. Hoteit, P.K. Prihatato, T. Chronis, G. Triantafyllou, and Y. Abualnaja
Mesopelagic Fishes – Underestimated and Underrated?
Stein Kaartvedt (King Abdullah University of Science and Technology)
Abstract
The mesopelagic realm (200-1000 m) is defined as the part of the ocean with too little light for photosynthesis, still with sufficient light to be exploited by organisms with very sensitive eyes. Mesopelagic fish occur in all the worlds’ oceans, inhabiting the mesopelagic realm during daytime, to a varying extent carrying out nocturnal feeding migrations to upper layers. The current world abundance estimate is 1 billion tones, i.e. an order of magnitude higher than the global yearly fisheries. This likely is an underestimate by at least one order of magnitude. Mesopelagic fishes locate their prey by sight and they may be particularly efficient in locating prey in clearwater systems, like the large oceanic gyres. Such oligotrophic systems are much less studied than those at high latitudes. In this talk I present data on mesopelagic fish from the Red Sea and high latitudes, and show evidence why mesopelagic fish standing stock likely is severely underestimated in the world’s oceans. A potential 10-100 times upgrading of the current global estimate would equal a mesopelagic fish biomass 100-1000 times larger than the worlds’ yearly fishery catch. This would force us to rethink their role as predators on zooplankton, as prey for top predators, as well as daily vertical transporters of organic matter from the epipelagic to the mesopelagic realm.
A High-Resolution Operational Forecast Model of Circulation and Oxygen on the Texas-Louisiana Continental Shelf and Slope
Xiaoqian Zhang (Texas A&M University)
Abstract
A new operational model of circulation and oxygen over the Texas-Louisiana continental shelf and slope, based on the Regional Ocean Modeling System (ROMS) is presented. The model is designed with a number of practical applications in mind: to investigate the mechanisms controlling seasonal hypoxia, understand the origins of harmful algal blooms, and predict oil spill trajectories on the Texas-Louisiana continental shelf and slope. This model consists two parts, i.e., the hindcast and operational components. The hindcast model is forced with the observed freshwater fluxes from the nine major Texas and Louisiana rivers, surface winds, and heat fluxes from the North American Regional Reanalysis (NARR) dataset. The hindcast simulations are carried out over ~8-year period from February 2003 to June 2011. The operational model, which provides nowcast and a 5-day forecast, starts from July 2011 with a different surface momentum and heat flux forcing from Global Forecast System (GFS). This model is nested to the Gulf of Mexico HYCOM, which provides realistic open boundary conditions. Model performance is quantified based on the model skills calculated using measurements from the Texas Automated Buoy System (TABS), and satellite altimetry data. The model is able to reproduce not only the seasonal pattern of sea surface height (SSH), temperature, and velocity fields, but also the strong sea-breeze-driven near-inertial surface currents, which have been found dominant in this region during the summer months. The hydrodynamical model also has an oxygen module that enables it to study the hypoxia in this region.
Hierarchical Models of Invasive Plant Species Distributions in the Northeastern United States
Huiyan Sang (Texas A&M University)
Abstract
In this work we use a Bayesian hierarchical statistical approach, spatial predictive process modeling, to predict the distribution of a major invasive plant species, Celastrus orbiculatus, in the northeastern USA. We also use this approach to model simultaneously the distributions of a set of four major invasive species in a spatially explicit multivariate model on a large data set. This multispecies analysis demonstrates that some pairs of species exhibit negative residual spatial covariation, suggesting potential competitive interaction or divergent responses to unmeasured factors.
Tracking and Encounter Data in Marine Environments
Chris Field (Dalhousie University Halifax, Canada)
Abstract
In this talk, we’ll begin by looking at racking data obtained on leatherback turtles as they migrate from Nova Scotia to the Caribbean. A simple state space model is formulated to assess the turtle’s navigational ability. We’ll address a number of issues which arise in the analysis of such tracking data. As a next step, we consider encounter style data arising from tagged animals, either two predators or a predator and a prey. This data arises from the Ocean Tracking Network headquartered at Dalhousie whose aim is to obtain a comprehensive examination of marine life and ocean conditions with emphasis on understanding responses to climate change.