Modeling the Effects of Physical and Biogeochemical Processes on Phytoplankton Species and Carbon Production in the Equatorial Pacific Ocean

The primary objective of this research is to investigate phytoplankton community response to variations in physical forcing and biological processes in the Cold Tongue region of the equatorial Pacific Ocean at 0°N, 140°W. This research objective was addressed using a one-dimensional multi-component lower trophic level ecosystem model that includes detailed algal physiology, such as spectrally-dependent photosynthetic processes and iron limitation on algal growth. The ecosystem model is forced by a one-year (1992) time series of spectrally-dependent light, temperature, and water column mixing obtained from a Tropical Atmosphere-Ocean (TAO) Array mooring. Autotrophic growth is represented by five algal groups, which have light and nutrient utilization characteristics of low-light adapted Prochlorococcus, highlight adapted Prochlorococcus, Synechococcus, autotrophic eukaryotes, and large diatoms. The simulated distributions and rates are validated using observations from the 1992 U.S. Joint Global Ocean Flux Study Equatorial Pacific cruises. The model-data comparisons show that the simulations successfully reproduce the temporal distribution of each algal group and that multiple algal groups are needed to fully resolve the variations observed for phytoplankton communities in the equatorial Pacific. The 1992 simulations show seasonal variations in algal species composition superimposed on which are shorter time scale variations (e.g., 8-20 days) that arise from changes in the upwelling/downwelling environmental structure. The simulated time evolution of the algal groups shows that eukaryotes are the most abundant group, being responsible for half of the annual biomass and 69% of the primary production and export. Filtering out low frequency physical forcing results in a 30% increase in primary production and dominance of high-light adapted Prochlorococcus and autotrophic eukaryotes. Sensitivity studies show that iron availability is the primary control on carbon export and production; whereas, algal biomass concentration is largely regulated by zooplankton grazing. Recycled iron is an important component of the ecosystem dynamics because sustained growth of algal groups depends on remineralized iron which accounts for 40% of the annual primary production in the Cold Tongue region. The effects of El Niño-Southern Oscillation (ENSO) processes on the lower trophic levels of Cold Tongue region were examined with eight-year simulations for a time, 1991-1999, that included three ENSO cycles. As a comparison, simulations were done for a region in the western Pacific at 165°E at the equator, which is known as the Warm Pool. The simulated response of the lower trophic levels in the two regions of the equatorial Pacific to ENSO cycles differs in community structure and level of production. For the Cold Tongue region, the ENSO warm phase results in a shift to small algal forms (e.g., Prochlorococcus spp. and Synechecoccus) and low primary productivity (25 mmol C m-2 d-1 versus an annual average of 75 mmol C m-2 d-1). For the Warm Pool region, the phytoplankton community is dominated by larger algal forms (e.g., autotrophic eukaryotes) and primary production increases (150 mmol C m-2 d-1 versus an annual average of 59 mmol C m-2 d-1). Also, during ENSO events carbon production and export in the Cold Tongue are limited by iron, whereas the relative abundance of iron and macronutrients (i.e. nitrate, silicate) limits production and export in the Warm Pool

Simulations of Phytoplankton Species and Carbon Production in the Equatorial Pacific Ocean 1. Model Configuration and Ecosystem Dynamics

The primary objective of this research is to investigate phytoplankton community response to variations in physical forcing and biological processes in the Cold Tongue region of the equatorial Pacific Ocean at 0N, 140W. This research objective was addressed using a one-dimensional multicomponent lower trophic level ecosystem model that includes detailed algal physiology, such as spectrally-dependent photosynthetic processes and iron limitation on algal growth. The ecosystem model is forced by a one-year (1992) time series of spectrally-dependent light, temperature, and water column mixing obtained from a Tropical Atmosphere-Ocean (TAO) Array mooring. Autotrophic growth is represented by five algal groups, which have light and nutrient utilization characteristics of low-light adapted Prochlorococcus, high-light adapted Prochlorococcus, Synechococcus, autotrophic eukaryotes, and large diatoms. The simulated distributions and rates are validated using observations from the 1992 U. S. Joint Global Ocean Flux Study Equatorial Pacific cruises. The modeldata comparisons show that the simulations successfully reproduce the temporal distribution of each algal group and that multiple algal groups are needed to fully resolve the variations observed for phytoplankton communities in the equatorial Pacific. The 1992 simulations show seasonal variations in algal species composition superimposed on shorter time scale variations (e.g., 8–20 days) that arise from changes in the upwelling/downwelling environmental structure. The simulated time evolution of the algal groups shows that eukaryotes are the most abundant group, being responsible for half of the annual biomass and 69% of the annual primary production and organic carbon export

Simulations of Phytoplankton Species and Carbon Production in the Equatorial Pacific Ocean 2. Effects of Physical and Biogeochemical Processes

A one-dimensional multi-component lower trophic level ecosystem model that includes detailed algal physiology is used to investigate the response of phytoplankton community and carbon production and export to variations in physical and biochemical processes in the Cold Tongue region of the equatorial Pacific Ocean at ON, 140W. Results show that high-frequency variability in vertical advection and temperature is an important mechanism driving the carbon export. Filtering out low frequency physical forcing results in a 30% increase in primary production and dominance of high-light adapted Prochlorococcus and autotrophic eukaryotes. Sensitivity studies show that iron availability is the primary control on carbon export and production; whereas, algal biomass concentration is largely regulated by zooplankton grazing. Recycled iron is an important component of the ecosystem dynamics because sustained growth of algal groups depends on remineralized iron which accounts for 4.0% of the annual primary production in the Cold Tongue region. Sensitivity studies show that although all algal groups have a considerable effect on simulated phytoplankton carbon biomass, not all have a strong effect on primary production and carbon export. Thus, these sensitivity studies indicate that it may not be necessary to represent a broad spectrum of algal groups in carbon cycle models, because a few key groups appear to have a large influence on primary production and export variability. Combining the low-light adapted Prochlorococcus, high-light adapted Prochlorococcus and Synechococcus groups as a single group and using a three algal group model may be sufficient to simulate primary production and export variability in the tropical Pacific waters. The results from this modeling study suggest that the net effect of increased stratification and temperature conditions is a decrease in carbon export in the Cold Tongue region and a shift in the phytoplankton community towards smaller algal forms (e.g., Prochlorococcus spp. and Synechecoccus). Increased stratification can result in decreased iron concentration and reduced vertical velocities, both of which contribute to decreased carbon export. Also, stratified conditions enhance the remineralization rate of nutrients (e.g., iron), which enhances carbon production. Thus, inclusion of iron dynamics in climate models may be needed to fully represent the effect of climate variability on equatorial Pacific ecosystems

Climatic controls on biophysical interactions in the Black Sea under present day conditions and a potential future (A1B) climate scenario

A dynamical downscaling approach has been applied to investigate climatic controls on biophysical interactions and lower trophic level dynamics in the Black Sea. Simulations were performed under present day conditions (1980–1999) and a potential future (2080–2099) climate scenario, based on the Intergovernmental Panel for Climate Change A1B greenhouse gas emission scenario. Simulations project a 3.7 °C increase in SST, a 25% increase in the stability of the seasonal thermocline and a 37 day increase in the duration of seasonal stratification. Increased winter temperatures inhibited the formation of Cold Intermediate Layer (CIL) waters resulting in near complete erosion of the CIL, with implications for the ventilation of intermediate water masses and the subduction of riverine nutrients. A 4% increase in nitrate availability within the upper 30 m of the water column reflected an increase in the retention time of river water within the surface mixed-layer. Changes in thermohaline structure, combined with a 27% reduction in positive wind stress curl, forced a distinct change in the structure of the basin-scale circulation. The predominantly cyclonic circulation characteristic of contemporary conditions was reversed within the southern and eastern regions of the basin, where under A1B climatic conditions, anticyclonic circulation prevailed. The change in circulation structure significantly altered the horizontal advection and dispersion of high nutrient river waters originating on the NW self. Net primary production increased by 5% on average, with much spatial variability in the response, linked to advective processes. Phytoplankton biomass also increased by 5% and the higher nutrient environment of the future scenario caused a shift in species composition in favour of larger phytoplankton. No significant change in zooplankton biomass was projected. These results constitute one of many possible future scenarios for the Black Sea, being dependent on the modelling systems employed in addition to the choice of emission scenario. Our results emphasise in particular the sensitivity of dynamical downscaling studies to the regional wind forcing fields extracted from global models (these being typically model dependent). As atmospheric warming is projected with a high degree of confidence warming of the Black Sea upper layer, increased water column stability, and erosion of the CIL are believed to be robust results of this study

Modelling impacts of drivers on biodiversity and ecosystems

Purpose of this chapter: Explores key issues in modelling impacts of changes in direct drivers on biodiversity and ecosystems; and critically reviews major types of models for generating outputs that are either directly relevant to assessment and decision-support activities, or are required as inputs to subsequent modelling of nature’s benefits to people. Key findings: 1-Models of biodiversity and ecosystem function are critical to our capability to predict and understand responses to environmental change; 2- There is a need to match biodiversity and ecosystem function model development to stakeholder and policy needs; 3- Biodiversity and ecosystem modelling depends heavily on our understanding of ecosystem structure, function and process and on their adequate representation in models; 4- Uncertainty in ecosystem dynamics is inherent in ecosystem modelling.EEA Santa CruzFil: Brotons, Lluís. InForest jru. Creaf-Ctfc; EspañaFil: Christensen, Villy. The University of British Columbia; Canadá.Fil: Ravindranath, N. H. India Center for Sustainable Technologies. Indian Institute of Science; India.Fil: Cao, Mingchang. Keqiang Zhao; China.Fil: Chun, Jung Hwa. National Institute of Forest Science, Division of Forest Ecology; Corea del SurFil: Maury, Olivier. Institut de Recherche pour le Développement (IRD); Francia.Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Proença, Vânia. Instituto Superior Tecnico - UNIU Lisboa; Portugal.Fil: Salihoglu, Baris. Middle East Technical University. Institute of Marine Sciences; Turquí

Challenges in integrative approaches to modelling the marine ecosystems of the North Atlantic: Physics to Fish and Coasts to Ocean

It has long been recognized that there are strong interactions and feedbacks between climate, upper ocean biogeochemistry and marine food webs, and also that food web structure and phytoplankton community distribution are important determinants of variability in carbon production and export from the euphotic zone. Numerical models provide a vital tool to explore these interactions, given their capability to investigate multiple connected components of the system and the sensitivity to multiple drivers, including potential future conditions. A major driver for ecosystem model development is the demand for quantitative tools to support ecosystem-based management initiatives. The purpose of this paper is to review approaches to the modelling of marine ecosystems with a focus on the North Atlantic Ocean and its adjacent shelf seas, and to highlight the challenges they face and suggest ways forward. We consider the state of the art in simulating oceans and shelf sea physics, planktonic and higher trophic level ecosystems, and look towards building an integrative approach with these existing tools. We note how the different approaches have evolved historically and that many of the previous obstacles to harmonisation may no longer be present. We illustrate this with examples from the on-going and planned modelling effort in the Integrative Modelling work package of the EURO-BASIN programme

A MSFD complementary approach for the assessment of pressures, knowledge and data gaps in Southern European Seas : the PERSEUS experience

PERSEUS project aims to identify the most relevant pressures exerted on the ecosystems of the Southern European Seas (SES), highlighting knowledge and data gaps that endanger the achievement of SES Good Environmental Status (GES) as mandated by the Marine Strategy Framework Directive (MSFD). A complementary approach has been adopted, by a meta-analysis of existing literature on pressure/impact/knowledge gaps summarized in tables related to the MSFD descriptors, discriminating open waters from coastal areas. A comparative assessment of the Initial Assessments (IAs) for five SES countries has been also independently performed. The comparison between meta-analysis results and IAs shows similarities for coastal areas only. Major knowledge gaps have been detected for the biodiversity, marine food web, marine litter and underwater noise descriptors. The meta-analysis also allowed the identification of additional research themes targeting research topics that are requested to the achievement of GES. 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license.peer-reviewe

A multi-model evaluation of ecosystem indicators´ performance

Shin, Yunne-Jai ... et. al.-- International Council for the Exploration of the Sea Annual Science Conference (ICES ASC 2014), Sustainability in a changing ocean, 15-19 September 2014, La CoruñaPeer Reviewe

BlueMed preliminary implementation plan

Support knowledge sharing about health, evolution and functioning of Mediterranean basin’s marine and coastal ecosystems with researchers, public policy makers and private sector to ensure the preservation of the basin’s resources, develop sustainable activities, control pressures and anticipate the responses to global change. Strengthen the open access to high-quality data both to create a common understanding of Mediterranean challenges and to support smart and innovative data applications in marinerelated economic activities. The goal calls to support in parallel the development of a Mediterranean observing system of systems to enable the collection of high-quality data on marine and coastal environments (see Priority 4).peer-reviewe