West-Central Australian Shelf
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LME 44: West-Central Australian Shelf

Bordering country:

Australia

LME total area:

543,577 km²

LME overall risk:

This LME falls in the cluster of LMEs that exhibit high rates of increase in MPA coverage.
Based on a combined measure of the Human Development Index and the averaged indicators for fish & fisheries and pollution & ecosystem health modules, the overall risk factor is very low.

Productivity

Chlorophyll-A:

The annual Chlorophyll a concentration (CHL) cycle has a maximum peak (0.226 mg.m^-3) in July and a minimum (0.105 mg.m^-3) during December. The average CHL is 0.145 mg.m^-3. Maximum primary productivity (153 g.C.m^-2.y^-1) occurred during 2000 and minimum primary productivity (122 g.C.m^-2.y^-1) during 2002. There is a statistically insignificant decreasing trend in Chlorophyll of -10.0 % from 2003 through 2013. The average primary productivity is 141 g.C.m^-2.y^-1, which places this LME in Group 2 of 5 categories (with 1 = lowest and 5= highest).

Primary productivity:

Sea Surface Temperature:

From 1957 to 2012, the West-Central Australian Shelf LME #44 has warmed by 0.96°C, thus belonging to Category 2 (fast warming LME). The first 25 years since 1957 were rather quiet and relatively cold. The single pronounced cold event of 1968 was also observed in the Sulu-Celebes Sea LME #37 (in 1967), Indonesian Sea LME #38 (in 1967), Northwest Australian Shelf LME #45, and Southwest Australian LME #43. The cold event of 1968 was preceded by the all-time minimum in the Indonesian Sea in 1967 and a minimum of 1967 in the North Australian Shelf LME #39. Therefore, this low-temperature signal was likely transported by the Indonesian Throughflow from the Indonesian Sea onto Western Australia’s shelves (LMEs ## 44 and 45), and father south and east, with the Leeuwin Current, onto the Southwest Australian Shelf LME #43. The last three decades featured strong events with peak-to-trough amplitude of 1°C. The two warm events of 1983-84 and 1988-89 were possibly correlated with moderate El Niños. The peak of 1998 was likely linked to the extremely strong El Niño 1997-98.

Fish and Fisheries

Production in Australian waters is limited by low levels of nutrients and as a result, fish populations are relatively small. Many species are endemic to Australia. There are commercial fisheries for Australian spiny lobster, abalone, pink snapper, shark, crab, pilchard, prawn and scallop.

Annual catch:

Total reported landings in the LME peaked at around 23,000 t in 2004. Invertebrates such as Australian spiny lobster, scallops, prawns and shrimps account for the largest share of the landings in the LME.

Catch value:

The reported landings were worth about 180 million US$ (in 2005 real US$) in 1990.

Marine Trophic Index and Fishing-in-Balance index:

The MTI in this LME was generally low, due to the low trophic level of Australian spiny lobster which accounts for the largest share of the reported landings. In recent years, however, both MTI and FiB index are on a rise, suggestive of spatial expansion.

Stock status:

The Stock-Catch Status Plots indicate that about 50% of the stocks are deemed as collapsed or overexploited. However, about 50% of the reported landings are supplied by developing stocks.

Catch from bottom impacting gear:

The percentage of catch from the bottom gear type to the total catch increased from 2% in the early 1950s to its first peak at around 23% in 1983. Then, this percentage fluctuated between 15% and 20% in recent decade.

Fishing effort:

The total effective effort continuously increased from around 1 million kW in the 1950s to its peak around 36 million kW in 2001.

Primary Production Required:

The primary production required (PPR) to sustain the reported landings is very small (less than 1.5%), in line with the low exploitation of the LME.

Catch potential projections (under global warming):

Pollution and Ecosystem Health

Pollution

Nutrient ratio, Nitrogen load and Merged Indicator:

Human activities in watersheds are affecting nutrients transported by rivers into LMEs. Large amounts of nutrients (in particular nitrogen load) entering coastal waters of LMEs can result in high biomass algal blooms, leading to hypoxic or anoxic conditions, increased turbidity and changes in community composition, among other effects. In addition, changes in the ratio of nutrients entering LMEs can result in dominance by algal species that have deleterious effects (toxic, clog gills of shellfish, etc.) on ecosystems and humans.
An overall nutrient indicator (Merged Nutrient Indicator) based on 2 sub-indicators: Nitrogen Load and Nutrient Ratio (ratio of dissolved Silica to Nitrogen or Phosphorus - the Index of Coastal Eutrophication Potential or ICEP) was calculated.

Nitrogen load:

The Nitrogen Load risk level for contemporary (2000) conditions was very low. (level 1 of the five risk categories, where 1 = lowest risk; 5 = highest risk). Based on a “current trends” scenario (Global Orchestration), this remained the same in 2030 and 2050.

Nutrient ratio:

The Nutrient Ratio (ICEP) risk level for contemporary (2000) conditions was moderate (3). According to the Global Orchestration scenario, this remained the same in 2030 and 2050.

Merged nutrient indicator:

The risk level for the Merged Nutrient Indicator for contemporary (2000) conditions was very low (1). According to the Global Orchestration scenario, this remained the same in 2030 and 2050.

POPs:

Four samples from 3 locations are available for the West-central Australian Shelf LME. Minimal average concentrations (ng.g^-1 of pellets) of 6 (range 0.5-13 ng.g^-1) were found for PCBs, 3.3 (range 2-7 ng.g^-1) for DDTs, and 0.1 (range 0.1- 0.2) for HCHs, all corresponding to risk category 1 of the five risk categories (1 = lowest risk; 5 = highest risk). This is probably due to minimal anthropogenic activities involving the use of POPs (PCBs in industries and DDT and HCH pesticides in agriculture).

Plastic debris:

Modelled estimates of floating plastic abundance (items km^-2), for both micro-plastic (<4.75 mm) and macro-plastic (>4.75 mm), indicate that this LME is in the group with relatively high levels of plastic concentration. Estimates are based on three proxy sources of litter: shipping density, coastal population density and the level of urbanisation within major watersheds, with enhanced run-off. The high values are due to the relative importance of these sources in this LME. The abundance of floating plastic in this category is estimated to be on average over 100 times higher that those LMEs with lowest values. There is limited evidence from sea-based direct observations and towed nets to support this conclusion.

Ecosystem Health

Mangrove and coral cover:

0.003% of this LME is covered by mangroves (US Geological Survey, 2011) and 0.15% by coral reefs (Global Distribution of Coral Reefs, 2010).

Reefs at risk:

This LME has a present (2011) integrated threat index (combining threat from overfishing and destructive fishing, watershed-based and marine-based pollution and damage) of 111. 0.4% of coral reefs cover is under very high threat, and 4% under high threat (of the 5 possible threat categories, from low to critical). When combined with past thermal stress (between 1998 and 2007), these values increase to 4% and 1% for very high and high threat categories respectively. By year 2030, 0.9% of coral cover in this LME is predicted to be under very high to critical level of threat from warming and acidification; this proportion increases to 1.4% by 2050.

Marine Protected Area change:

The West Central Australian Shelf LME experienced an increase in MPA coverage from 0 km² prior to 1983 to 194,208 km² by 2014. This represents an increase of 30,000%, within the highest category of MPA change.

Cumulative Human Impact:

The West Central Australian Shelf LME experiences above average overall cumulative human impact (score 3.87; maximum LME score 5.22), which is also well above the LME with the least cumulative impact. It falls in risk category 4 of the five risk categories (1 = lowest risk; 5 = highest risk). This LME is most vulnerable to climate change. Of the 19 individual stressors, three connected to climate change have the highest average impact on the LME: ocean acidification (1.03; maximum in other LMEs was 1.20), UV radiation (0.70; maximum in other LMEs was 0.76), and sea surface temperature (1.55; maximum in other LMEs was 2.16). Other key stressors include commercial shipping, sea level rise, ocean based pollution, and pelagic high-bycatch commercial fishing.

Ocean Health Index:

The West Central Australian Shelf LME scores above average on the Ocean Health Index compared to other LMEs (score 79 out of 100; range for other LMEs was 57 to 82 but still relatively low. This score indicates that the LME is below its optimal level of ocean health, although there are some aspects that are doing well. Its score in 2013 increased 1 point compared to the previous year, due in large part to changes in the scores for natural products and coastal livelihoods. This LME scores lowest on food provision and coastal protection goals and highest on artisanal fishing opportunities, carbon storage, coastal livelihoods & economies, clean water and habitat biodiversity goals. It falls in risk category 1 of the five risk categories, which is the lowest level of risk (1 = lowest risk; 5 = highest risk).

Socio-economics

Indicators of demographic trends, economic dependence on ecosystem services, human wellbeing and vulnerability to present-day extreme climate events and projected sea level rise, are assessed for this LME. To compare and rank LMEs, they were classified into five categories of risk (from 1 to 5, corresponding to lowest, low, medium, high and highest risk, respectively) based on the values of the individual indicators. In the case of economic revenues, the LMEs were grouped to 5 classes of revenues from lowest, low, medium, high and highest, as revenues did not translate to risk.

Population:

The coastal area stretches over 140,036 km². A current population of 1 698 thousand in 2010 is projected to increase to 2 056 thousand in 2100, with a density of 12 persons per km² in 2010 increasing to 15 per km² by 2100. About 19% of coastal population lives in rural areas, and is projected to increase in share to 28% in 2100.

Coastal poor:

The indigent population makes up 14% of the LME’s coastal dwellers. This LME places in the medium-risk category based on percentage and in the low-risk category using absolute number of coastal poor (present day estimate).

Revenues and Spatial Wealth Distribution:

Fishing and tourism depend on ecosystem services provided by LMEs. This LME ranks in the low-revenue category in fishing revenues based on yearly average total ex-vessel price of US 2013 $174 million for the period 2001-2010. Fish protein accounts for 8% of the total animal protein consumption of the coastal population. Its yearly average tourism revenue for 2004-2013 of US 2013 $15 953 million places it in the medium-revenue category. On average, LME-based tourism income contributes 12% to the national GDPs of the LME coastal states. Spatial distribution of economic activity (e.g. spatial wealth distribution) measured by night-light and population distribution as coarse proxies can range from 0.0000 (totally equal distribution and lowest risk) to 1.0000 (concentrated in 1 place and most inequitable and highest risk). The Night Light Development Index (NLDI) thus indicates the level of spatial economic development, and that for this LME falls in the category with very low risk.

Human Development Index:

Using the Human Development Index (HDI) that integrates measures of health, education and income, the present-day LME HDI belongs to the very high HDI and very low-risk category. Based on an HDI of 0.942, this LME has an HDI Gap of 0.058, the difference between present and highest possible HDI (1.000). The HDI Gap measures an overall vulnerability to external events such as disease or extreme climate related events, due to less than perfect health, education, and income levels, and is independent of the harshness of and exposure to specific external shocks.
HDI values are projected to the year 2100 in the contexts of shared socioeconomic development pathways (SSPs). This LME is projected to assume a place in the very low risk category (very high HDI) in 2100 under a sustainable development pathway. Under a fragmented world scenario, the LME is estimated to place in a medium-risk category (medium HDI) because of reduced income levels and increasing population values from those in a sustainable development pathway.

Climate-Related Threat Indices:

The Climate-Related Threat Indices utilize the HDI Gaps for present-day and projected 2100 scenarios. The contemporary climate index accounts for deaths and property losses due to storms, flooding and extreme temperatures incurred by coastal states during a 20-year period from 1994 to 2013 as hazard measures, the 2010 coastal population as proxy for exposure, and the present day HDI Gap as vulnerability measure.
The Contemporary Threat Index incorporates a Dependence Factor based on the fish protein contribution to dietary animal protein, and on the mean contribution of LME tourism to the national GDPs of LME coastal states. The HDI Gap and the degree of dependence on LME ecosystem services define the vulnerability of a coastal population. It also includes the average of risk related to extreme climate events, and the risk based on the degrading system states of an LME (e.g. overexploited fisheries, pollution levels, decrease in coastal ecosystem areas).
The 2100 sea level rise threat indices, each computed for the sustainable world and fragmented world development pathways, use the maximum projected sea level rise at the highest level of warming of 8.5 W/m² in 2100 as hazard measure, development pathway-specific 2100 populations in the 10 m × 10 km coast as exposure metrics, and development pathway-specific 2100 HDI Gaps as vulnerability estimates.
Present day climate threat index of this LME is within the very low-risk (very low threat) category. The combined contemporaneous risk due to extreme climate events, degrading LME states and the level of vulnerability of the coastal population, is very low. In a sustainable development scenario, the risk index from sea level rise in 2100 is very low, and increases to low under a fragmented world development pathway.