Butterfly population dynamics: Stability, outbreaks and extinctions.

Presentation by Myron (‘Meron’) P. Zalucki

BSc 1972-74 (ANU)
Honours 1976 (ANU)
PhD 1977-1981 (Griffith)
1981-2021 (UQ)

Lepidoptera: an order of insects that includes butterflies and moths. The name means scale (lepis)-wing (pteron) from ancient Greek.. 

What is population dynamics?

• Change in the abundance and distribution of a species over time
• Butterfly populations show a wide range of dynamic “behaviours” in both time and space
• Stable? Outbreaks, extinctions…

We record changes in abundance, Nt, the number of animals at a particular stage of development (e.g. adults), over time from a series of samples.

To download a .pdf of the full presentation click here.

(This information comes from  a talk given by Dr Myron P Zalucki at a CDEA public meeting on 25 February 2021)

Can weeds save a rainforest? Fragmentation, Restoration and Succession

Presentation by Dr John Hall, 

School of Biological Sciences, 

The University of Queensland

Although seldom talked about, habitat fragmentation is one of the fundamental issues of our age. Secondary regrowth - where vegetation regrows naturally and spontaneously following a history of habitat loss, without human intervention or management - can restore much needed biodiversity and connectivity to
fragmented landscapes. However, such "passive restoration" may be degraded in the sense of having reduced species diversity, and a dominance of exotic weeds. Intuitively, such "weed forests" seem a poor outcome, but in this talk he presented some surprising results from the Camphor Laurel forests that dominate regrowth on former rainforest lands in northern New South Wales.

Although these forests are indeed dominated by the exotic weed camphor laurel today, they already harbour a surprising diversity of native species, and - what is more exciting - there is clear evidence that over time they are likely to transition into a vegetation that increasingly resembles native rainforest. Far from being an ecological disaster-area, in this instance the weed-dominated regrowth may in fact represent an important conservation asset in the landscape. 

(This information comes from  a talk given by Dr John Hall at a CDEA public meeting on 28 February 2019)

The Birds at my Table

Presentation by Professor Darryl Jones,

Griffith School of Environment & Environmental Futures Research Institute,

Griffith University.

Professor Darryl Jones is an urban ecology expert and a bird feeder. That combination is incredibly unusual in Australia.  "The predominant advice is generally to avoid feeding birds," Professor Jones said.  "But, since I started investigating this, I've turned my views completely around."Professor Darryl Jones is an urban ecology expert and a bird feeder. That combination is incredibly unusual in Australia.  "The predominant advice is generally to avoid feeding birds," Professor Jones said.  "But, since I started investigating this, I've turned my views completely around."It all started with magpies.  When trying to quantify the types of things that urban magpies were feeding to their chicks, Professor Jones found that he could not identify everything that was being brought to the nest.  The Brisbane-based ecologist tracked the magpies around his neighbourhood and found that they were being fed mince, salami, cheese, diced heart and even steak by local residents.  "We had no idea it was happening to such an extent," Professor Jones told the ABC's Off Track podcast.  "And at the time, like everybody else, I thought, 'Everybody knows you don't feed birds, it just can't be a true thing'."

To download a pdf file of the full presentation click here.

(Professor Darryl Jones spoke at a CDEA public meeting on 9 August 2018.  This summary is taken from  the  ABC News website.)

Climate change in Australia: A lot of hot air or in hot water?

Professor Anthony Richardson

School of Mathematics & Physics,

The University of Queensland and CSIRO

There is a lot of confusion around climate change and a lot of comments from people who know very little about the topic. There seems to be a misguided view that everyone’s opinion is equal when it comes to topics that require a level of expertise and knowledge. When I take my car to the mechanic, I don’t argue with him when he says that the brakes need fixing – I trust his expertise. I don’t think everyone’s opinion is equal when it comes to the safety of my family in the car (certainly not mine, as I know nothing about cars!), and I don’t think everyone’s opinion is equal when it comes to the safety of my family with climate change. Science is not an opinion, but a testable body of knowledge that evolves as we learn more.

In this presentation, I tried to share some of my knowledge about climate change – particularly in my area of expertise which is the current and future impacts of climate change on biodiversity. I started with probably the most compelling evidence showing the increase in carbon dioxide – a time series of carbon dioxide over 800,000 years from atmospheric and ice core measurements produced by NOAA in the US (https://www.youtube.com/watch?v=pVYt9ZDDfBs&t=14s) .

Click here to download the full pdf of Professor Richardson's presentation

(This information comes from  a talk given by Professor Anthony Richardson at a CDEA public meeting on 10 May 2018)

Sharks & Rays of the Brisbane River and Moreton Bay

Professor Mike Bennett

School of Biomedical Sciences, The University of Queensland

Background: The Big Picture

Generally speaking, the public is relatively misinformed about sharks and disinterested and uninformed about rays. Sharks and rays are, however, key components of almost all marine ecosystems, and many species are endangered.

Sharks and rays are elasmobranchs, or cartilaginous fish, which are types of lower chordates. One characteristic of chordates is the presence of a notochord, which is a long flexible supporting rod that runs through at least part of the body.

There are about 1,200 species of cartilaginous fishes presently living, and Australia is home to about 75% of the World’s shark species. About 65% of sharks and rays occur in the Indo-West Pacific region.

Sharks range in length from 22cm to 10m while rays range in width from 25 to 700 cm. Reproductive periods range from 1.5 to 25 years for sharks, and from 1.5 to 17 years for rays. Sharks produce between 1 and 190 young, while rays produce between 1 and over 1000 young. Some sharks and rays are vegetarian while others are carnivores.

There was rapid worldwide depletion of predatory fish communities between 1952 and 1980.

Background: The Local Picture

The Brisbane River is 344km long, from its source in Mount Stanley to its mouth at Moreton Bay, and is tidal for 85km of its total length.

Only one shark, the Bull Shark, Carcharhinus leucas, occurs in the Brisbane River. We don’t know, but there may be hundreds of bull sharks in the tidal region from the mouth to the Mount Crosby Weir. There is also only one ray, the Estuary Ray, Hemitrygon fluviorum, found mainly from the mouth of the Brisbane River to the City Reach. There are probably fewer than 100 in this stretch of water. Physiologically, bull sharks and estuary rays can survive in these waters. There is sufficient food in this region, which also provides some protection from predators.

Background: The Bigger Picture

Globally, bull sharks are distributed in tropical and warm temperate regions, but the International Union for Conservation of Nature Red List includes them as “Near Threatened”. Estuary rays are distributed in shallow tropical and warm temperate water along the coast of Eastern Australia. Their status in the International Union for Conservation of Nature Red List is “Vulnerable”. There are a number of contributory factors to the poor status of these sharks and rays.

There are many more species of both sharks and rays in Moreton Bay – 34 species of sharks and 26 species of rays.

Different types of marine animals can co-exist in the same waters because of partitioning, related to a range of factors such as their position in the food chain, habitat, available food and time of day.

Professor Bennett presented some of the specific work of his own team of researchers.

(This information comes from  a talk given by Dr Mike Bennett at a CDEA public meeting on 7 February 2018)