that influence the biology of reefs and their subsequent bio-optical properties; and 4)
evaluation and increased utilization of a greater range of image data sources (e.g.
MODIS, IKONOS, and SeaWiFS).
6.2 A COMBINED FIELD AND REMOTELY SENSED PROGRAM FOR MAPPING
HARMFUL ALGAL BLOOMS
Blooms of the toxic cyanobacterium Lyngbya majuscula have become a significant
problem in Moreton Bay, southeast Queensland, Australia due to the large size of
blooms that have been occurring since 1997 (Figure 2) (Dennison, 1999). As the algae
produces skin and respiratory reactions, it has forced the closure of several net-fisheries
in the Bay, and also forced the closure and clean up of beaches used for recreational
purposes. From an ecological perspective, the smothering effect of the algae on
seagrass may be impacting the health of turtles and dugongs in the area where they feed
from the seagrass (Dennison, 1999; Watkinson, 2000). L. majuscula is a toxic,
filamentous, non-heterocystous marine cyanobacterium that fixes nitrogen. It is found
attached to seagrass, algae, and coral, and may rise to the water’s surface by internal
accumulation of gas bubbles (Watkinson, 2000). The L. majuscula blooms in Moreton
Bay occur over areas from 8 - 80 km
2
, with varying amounts of projected cover and
vertical thickness (i.e. up to one meter thick). The blooms may last over periods of
days to months (Watkinson, 2000; Roelfsema, 2001). L. majuscula blooms in the
Moreton Bay region have most recently been observed in large areas ( >1ha) on the
seagrass beds of Deception Bay and the clear waters of the Eastern Banks, though they
have also been observed in most locations throughout the Bay (Figure 2). Blooms have
been observed in other locations along the Australian coastline and other tropical
coastal regions throughout the world (e.g. Hawaiian islands, Cook Islands, Fiji, and
Eastern Africa).
6.2.2 Scientific and Community Monitoring Requirements
The negative impacts of L. majuscula blooms on fisheries, beach conditions, and
native marine fauna in Moreton Bay Marine Park were recognised quickly by the Local
Councils and State Government Agencies responsible for managing Moreton Bay.
These groups collaborated to form a “Lyngbya Taskforce” to collect baseline
information, monitor, understand, and manage the blooms. Baseline mapping of the
bloom extent and density for use in monitoring its changes was critical information.
This spatial information was used by scientists attempting to understand the causes and
dynamics of the bloom, and for the Marine Park Managers to restrict use of affected
sites. For example, the baseline mapping information was used to:
• provide Marine Park Managers with a basis for initiating mitigation (e.g.
selection of which beaches or areas to close and clean
• produce “Lyngbya Alert” maps on the Environmental Protection Agency’s
website to enable local residents to decide where to safely swim, fish or boat
• provide scientists with information to understand the bloom characteristics
(e.g. dynamics and origin)
240
Phinn, Joyce, Scarth and Roelfsema
6.2.1 Characteristics of Lyngbya majuscula as a Harmful Algal Bloom
evaluation and increased utilization of a greater range of image data sources (e.g.
MODIS, IKONOS, and SeaWiFS).
6.2 A COMBINED FIELD AND REMOTELY SENSED PROGRAM FOR MAPPING
HARMFUL ALGAL BLOOMS
Blooms of the toxic cyanobacterium Lyngbya majuscula have become a significant
problem in Moreton Bay, southeast Queensland, Australia due to the large size of
blooms that have been occurring since 1997 (Figure 2) (Dennison, 1999). As the algae
produces skin and respiratory reactions, it has forced the closure of several net-fisheries
in the Bay, and also forced the closure and clean up of beaches used for recreational
purposes. From an ecological perspective, the smothering effect of the algae on
seagrass may be impacting the health of turtles and dugongs in the area where they feed
from the seagrass (Dennison, 1999; Watkinson, 2000). L. majuscula is a toxic,
filamentous, non-heterocystous marine cyanobacterium that fixes nitrogen. It is found
attached to seagrass, algae, and coral, and may rise to the water’s surface by internal
accumulation of gas bubbles (Watkinson, 2000). The L. majuscula blooms in Moreton
Bay occur over areas from 8 - 80 km
2
, with varying amounts of projected cover and
vertical thickness (i.e. up to one meter thick). The blooms may last over periods of
days to months (Watkinson, 2000; Roelfsema, 2001). L. majuscula blooms in the
Moreton Bay region have most recently been observed in large areas ( >1ha) on the
seagrass beds of Deception Bay and the clear waters of the Eastern Banks, though they
have also been observed in most locations throughout the Bay (Figure 2). Blooms have
been observed in other locations along the Australian coastline and other tropical
coastal regions throughout the world (e.g. Hawaiian islands, Cook Islands, Fiji, and
Eastern Africa).
6.2.2 Scientific and Community Monitoring Requirements
The negative impacts of L. majuscula blooms on fisheries, beach conditions, and
native marine fauna in Moreton Bay Marine Park were recognised quickly by the Local
Councils and State Government Agencies responsible for managing Moreton Bay.
These groups collaborated to form a “Lyngbya Taskforce” to collect baseline
information, monitor, understand, and manage the blooms. Baseline mapping of the
bloom extent and density for use in monitoring its changes was critical information.
This spatial information was used by scientists attempting to understand the causes and
dynamics of the bloom, and for the Marine Park Managers to restrict use of affected
sites. For example, the baseline mapping information was used to:
• provide Marine Park Managers with a basis for initiating mitigation (e.g.
selection of which beaches or areas to close and clean
• produce “Lyngbya Alert” maps on the Environmental Protection Agency’s
website to enable local residents to decide where to safely swim, fish or boat
• provide scientists with information to understand the bloom characteristics
(e.g. dynamics and origin)
240
Phinn, Joyce, Scarth and Roelfsema
6.2.1 Characteristics of Lyngbya majuscula as a Harmful Algal Bloom