2016 SoE Marine Chapter - State and Trends - Algal blooms, jellyfish blooms

Brief description

The Marine chapter of the 2016 State of the Environment (SoE) report incorporates multiple expert templates developed from streams of marine data. This metadata record describes the Expert Assessment "The state and trends of ecological processes – algal blooms, jellyfish blooms". The full Expert Assessment, including figures and tables (where provided), is attached to this record. Where available, the Data Stream(s) used to generate this Expert Assessment are accessible through the "On-line Resources" section of this record.

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DESCRIPTION OF ECOLOGICAL PROCESS FOR EXPERT ASSESSMENT
--Algal Blooms--
Phytoplankton produce half the oxygen we breathe and sustain our fisheries. However, some species produce toxins when they proliferate, and can discolour the water resulting in obvious blooms. These Harmful Algal Blooms (HABs) can have serious economic, health and environmental impacts. In summer 2015/2016, there was a bloom of Alexandrium tamarense along the east coast of Tasmania – the most toxic bloom in 40 years. It contaminated mussels, oysters, scallops and ultimately rock lobsters – and led to closures lasting 4 months. This followed a HAB bloom in Tasmania in 2013 that cost $23 million. Because of their impact on the environment they are the most studied of algal species that bloom, and as a result this assessment focuses on this group of algae.

There is strong scientific consensus that eutrophication is the primary factor stimulating HABs. In addition, new toxic species can be introduced through ballast water exchange and tropical species are moving poleward into new areas in Australia.

--Jellyfish Blooms--
Jellyfish are important and often conspicuous components of ecosystems. Although dense jellyfish blooms are natural in healthy systems and there is debate about whether jellyfish populations are increasing globally, persistent blooms are known to be sensitive indicators of degraded systems. Jellyfish outbreaks can cause a number of deleterious effects including losses in tourist revenue through beach closures and even death of bathers (through stings); power outages following the blockage of cooling intakes at coastal power plants; burst fishing nets and contaminated catches; killing of farmed fish; and reduction in commercial fish abundance through competition and predation.

The two primary human pressures that exacerbate jellyfish blooms are:
1. Overfishing, particularly of small pelagic species such as anchovy and sardine, which releases predation pressure on young jellyfish; and
2. Eutrophication, where increased nutrients lead to more plankton food for jellyfish.

Problematic jellyfish blooms primarily occur in bays and harbours, areas covered under the coasts chapter. This assessment will concentrate on those data available from nearshore and shelf waters for which there are currently data available.

DATA STREAM(S) USED IN EXPERT ASSESSMENT
IMOS plankton data – both from the National Reference Stations and the Australian Continuous Plankton Recorder survey.

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2016 SOE ASSESSMENT SUMMARY [see attached Expert Assessment for full details]

• 2016 •
Assessment grade: Very good
Assessment trend: Stable
Confidence grade: Limited evidence or limited consensus
Confidence trend: Limited evidence or limited consensus
Comparability: Grade and trend somewhat comparable to the 2011 assessment
• 2011 •
Assessment grade: Very good
Assessment trend: Stable
Confidence grade: Limited evidence or limited consensus
Confidence trend: Limited evidence or limited consensus

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CHANGES SINCE 2011 SOE ASSESSMENT
Not previously assessed.

Lineage

Statement: QUALITY OF DATA USED IN THE ASSESSMENT
Best available.

Notes

Purpose
To describe the state and trends in algal blooms and jellyfish blooms for use in the Marine chapter of the 2016 State of the Environment report.