The value of EO for constructing indicators of marine ecosystem status

Monitoring the ocean ecosystem by
Remote Sensing
Trevor Platt and Shubha Sathyendranath
Plymouth Marine Laboratory, UK

Context: Stewardship of the Ocean
• Global consensus (UN Declaration): Management should have
ecosystem basis, system integrity should be maintained.
Preserve ecosystem attributes such as health, vigour, resilience,
• But these are difficult to quantify.
• Instead, develop suite of Ecological Indicators: objective metrics
for the pelagic ecosystem that can be applied serially, in
operational mode, to detect changes.

How to Quantify Ecosystem Integrity?
• Concepts such as the health, vigour and resilience of the
ecosystem are subjective and difficult to quantify
• Instead, develop suite of Ecological Indicators as an aid
to ecosystem-based management
• They are objective metrics for the pelagic ecosystem that
can be applied serially, in operational mode, to detect
changes that may occur in response to environmental
perturbation

Ideal Characteristics of Pelagic Indicators
• Represent a well-understood and widely-accepted
ecosystem property
• Quantifiable unambiguously in standard units
• Measurable rapidly at low incremental cost
• Repeat frequency compatible with intrinsic time scale
of properties under study
• Measurable at a variety of scales
• Possibility to create long (multi-decadal) time series
Platt and Sathyendranath, 2008

Remote sensing for Operational Metrics
• Meets requirements of speed, resolution, repeat
frequency and cost-effectiveness
• Autotrophic biomass important ecosystem property
• Primary production fields can also be generated
• SST and chlorophyll obtainable at same resolution
• Can construct time series: seasonal dynamics can be
quantified objectively
• Allows interannual comparisons
Platt and Sathyendranath 2008

Construction of time series possible
at any chosen scale of spatial averaging: provides the raw
material for construction of indicators
Seasonal signal is key
feature of the time series:
Spring bloom is dominant
event in seasonal cycle.
Inter-annual fluctuations in
phase are important
(Platt, Sathyendranath &
Fuentes-Yaco, 2007).

Some Ecological Indicators from Remote Sensing: Compact
description of pelagic ecosystem
Initiation of spring bloom
Amplitude of spring bloom
Timing of spring maximum Duration of spring bloom
Total production in spring bloom Annual phytoplankton production
Initial slope, light-saturation curve Assimilation number
Particulate organic carbon Phytoplankton carbon
Carbon-to-chlorophyll ratio Phytoplankton growth rate
Phytoplankton loss rate Integrated phytoplankton loss
Spatial variance in biomass field
Spatial variance in production field
Phytoplankton functional types
Biogeochemical provinces
Pelagic ecosystem can be represented as a time-dependent
vector whose elements are chosen from list of ecological
indicators. Choice of elements depends on the particular
applications envisaged. A concise description of ecosystem.
Platt and Sathyendranath, 2008

Fisheries & Other Applications of EO Indicators include:
• Harvest Fisheries
- economies of fuel and time
• Fisheries Management
- intelligence on ecosystem fluctuations
and effect on future states of exploited stocks
• Aquaculture Industry
- carrying capacity, harmful algal blooms
• Protection of Species at Risk
- exclusion zones and reduction of by-catch
• Marine Protected Areas & Vulnerable Marine Ecosystems
- delineation of these
• Ecosystem Health and Ecosystem Services
- monitoring health, evaluating services
• High Seas Governance
- international governance strategy, ecosystem
delineation, straddling stocks

What is the UK competence in this area?
International leader on scientific side (theory and demonstration
projects, especially in fisheries)
International leader on scientific side (CoastColour; CCI Ocean
Colour, SST and emerging synergies; IOCCG; GreenSEAS; GEO
Oceans & Society: the Blue Planet)
International leader on pre-operational side (MyOCEAN)
NERC National capability in ocean colour and SST (NEODAAS)
Marine component of NCEO Carbon Theme

What is the expected future?
Demand for information on ocean ecosystem can only
increase, in UK and abroad, for national, European
and international reasons
Biodiversity is becoming a household word. Potential
of remote sensing for marine biodiversity is yet to be
fully exploited
There is a vacant niche to be occupied