Fish Thinkers Research Group Youtube channel now online!

Follow the link below to watch our first youtube video! Make sure to watch in HD. It’s a short edit of my trip to Lord Howe Island to survey the marine parks fish populations using baited remote underwater video systems. More videos coming soon so stay tuned!

Urbanisation impacts abundance (but not richness) of salt marsh molluscs

Matt Rees:

A great summary by Ben Gooden on Geoff Clarke’s research examining the impact of urbanisation on salt marsh snails. It was a lot of fun hanging out counting snails in the mud, especially along the shores of Lake Illawarra (we saw some weird things). Make sure you head over to Ben’s blog for more interesting ecological posts!

Originally posted on Ben Gooden - Ecological Research:

salt marsh impactThe preliminary results are now in: urbanisation at the landward boundary of coastal salt marshes is associated with a two-fold reduction in the density of molluscs inhabiting adjacent coastal salt marsh. Our results found, however, that despite this reduction in overall molluscan abundance, urbanisation had no effect on the number of different mollusc species (i.e. richness) present in adjacent salt marshes.

The overall aim of this project was to examine effects of shoreline urbanisation on the unique molluscan fauna within endangered salt marsh of south-eastern Australia. My student, Geoff Clarke did a stellar job with this project, counting and identifying over 7,500 individual snails from six species, most of which are restricted to salt marsh or similar vegetation that borders estuaries and coastal embayments.

Geoff surveyed 9 ‘urbanised’ and 9 ‘forested’ (which he termed natural) reference sites across three embayments (see accompanying satellite images). Each site consisted of a…

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Surrogates for temperate reef biodiversity and their use in conservation

Earlier this year my co-authors and I published a paper in Diversity and Distributions that examined a cost-effective way of predicting reef biodiversity for conservation purposes. Here is some background on the issues surrounding the design of Marine Protected Areas (MPAs) and a brief summary of our research findings.

As most of us are aware, our oceans are not as healthy as they once were. On a global scale we are continuing to see a loss of marine biodiversity in our oceans. To address this issue, there has been a push for the global development of MPAs. Although justified by a huge number of studies revealing positive effects, MPA location and configuration is not often based on ecology, but rather driven by social, political or economic concerns. Therefore, MPAs may just be ‘leftover’ areas that do not effectively protect biodiversity and potentially give the public a false sense of security  (see here).

The problem with creating MPAs on an ecological foundation stems from the difficulties and costs in surveying marine biodiversity over the geographic areas required. Imagine surveying 100’s of square kilometres of ocean, counting all the fish, algae, snails, amongst other taxa, to determine where to place a no-take zone. It would cost a lot of money and take a lot of time! Plus, using SCUBA you’re limited by depth, restricting your surveys to relatively shallow areas.

An alternative approach is to use biodiversity ‘surrogates’ to predict areas of interest (i.e. where a certain species or community exists). A surrogate in an ecological sense is an ‘indicator’, which is easy to measure and correlates with what we want to conserve (i.e. biodiversity). A simple example of a surrogate could be using a plant community that is easy to survey from aerial photos. If this plant community supports a species of interest, say a rare bird, by mapping the distribution of the plant community, you could determine areas where the bird is likely to live in a cost effective way.

In the marine environment, scientists use habitat maps as surrogates for biodiversity and developing MPAs.  As different habitat classes (rocky reef, sand, seagrass, etc.) contain different species living within them, by representing a greater number of habitat classes in a MPA, we can assume we are protecting a high proportion of the biodiversity in that particular area.

However, a number of habitat classes such as temperate rocky reefs display considerable fine-scale variation. Reefs may be structurally complex or flat, they may be sheltered or exposed to swell, or they may be close to or far from sand, naming just a few examples. Previous studies have indicated that such characteristics are important in determining where animals live on temperate reefs. Therefore, incorporating this fine-scale reef variation in MPA design would increase the likelihood of representing and conserving reef biodiversity.

The exciting news is that remote sensing technologies (sonar, aerial photography, satellites, etc.) have improved so much that marine scientists can map the fine-scale structure of temperate reefs. Therefore we can now examine the potential of fine-scale reef variation as a surrogate for reef biodiversity. So in this study, we used high resolution (5 metre pixel size) bathymetric side-scan sonar imagery to:

  • Examine the fine-scale, physical variation of temperate reefs and test whether measures of reef variation provided surrogate measures for the abundance, diversity and community composition of sessile invertebrates (sponges and ascidians) and reef fishes.

We surveyed sessile invertebrates using a specialized towed underwater video system and reef fish using baited underwater video stations (BRUVs) – see pics below.

Baiting up the underwater video system with smelly pichards

Baiting up the underwater video system with smelly pichards

A broadnose seven gill shark recorded on one of our underwater video systems!

A broadnose seven gill shark recorded on one of our underwater video systems!

 

 

 

 

 

 

 

 

 

 

 

From the side-scan sonar imagery, we found massive differences in the structural complexity of temperate reefs. Some reefs were almost completely flat while others were complex. For example one reef dropped from a depth of 18 metres to a depth of 35 metres over a relatively short distance!

We found that reef structural complexity was a strong predictor of sessile invertebrates, with a greater abundance and diversity on reefs with high structural complexity. However a number of unique species were found only at sites with low structural complexity, indicating that flat reefs have conservation value too.

Generally, physical variables such as structural complexity were relatively poor predictors of the total abundance and diversity of fishes. However, we did find a higher abundance and diversity of fishes at sites further from the reef/sand boundary. In contrast, physical variables were good predictors of the abundance of Leatherjackets, with higher numbers observed further from the reef/sand boundary and at greater depths. This finding indicates that surrogacy relationships for fish may need to be explored at the family or specie level.

So in summary we found that:

  • Temperate reefs display considerable physical variation (i.e. structural complexity) which can be measured in a cost-effective and time efficient way using side-scan sonar.
  • Certain measures of reef variation are strong predictors of sessile invertebrates and Leatherjackets. Therefore these measures are potential surrogates for sessile invertebrates and Leatherjackets.
  • MPAs should represent the fine-scale variation of temperate reefs to better represent and protect temperate reef biodiversity.

For more information follow the link below!

Rees MJ, Jordan A, Price OF, Coleman MA, Davis AR (2014) Abiotic surrogates for temperate rocky reef biodiversity: implications for marine protected areasDiversity and Distributions 20, 284-296.

This research was supported by the University of Wollongong and NSW Department of Primary Industries.

Western Australian Shark Hazard Mitigation Drum Line Program

Lachlan Fetterplace:

 

Marty over at SQUIDDLED THOUGHTS posted today on where to go to make a submission on the proposed WA Shark Hazard Mitigation Drum Line Program 2014 – 2017. If its something you are interested in or care about then its worth taking a look.

Originally posted on Squiddled thoughts:

White_shark

The Environmental Protection Agency in Western Australian are now accepting submissions for public comment on the proposed WA Shark Hazard Mitigation Drum Line Program 2014 – 2017.

I would urge people to have a look at the documentation here and to make a submission here. On the face of it, I am personally opposed to the idea for the following reasons:

  1. I like sharks.
  2. Many species of non-target sharks are captured on drum lines.
  3. Other forms of marine life such as whales and turtles could become entangled.
  4. Great White Sharks, one of the “target” species, are listed as vulnerable under Western Australia’s legislation (Wildlife Conservation Act 1950 (Western Australia)). Great White Sharks are also listed as vulnerable under national legislation (Environment Protection and Biodiversity Conservation Act 1999). 
  5. Shark control programs such as those implemented in NSW and Qld have not significantly reduced shark attacks.
  6. Many, many more people die…

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Special marine ecology edition of the ESA bulletin is now online!

The latest Ecological Society of Australia bulletin, which I co-edited alongside Ben Gooden, is now up online! It has been such a great experience to invite some of Australia’s premier marine scientists to showcase their research in this special marine ecology issue. In this edition we have contributions by Emma JohnstonMelanie BishopRob HarcourtLuciana Möller and Guido Para, along with student contributions by Paul CarnellJulia Santana Garcon and our very own Lachlan Fetterplace. The bulletin covers a diverse range of current marine ecological research, from kelp forest dynamics to marine predators, ecotoxicology to cetacean behaviour and mudflat ecology to surveying fish with underwater cameras – so there is something for everyone!

You can read or download the bulletin here!

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The vast unknown: assessing the conservation of soft sediment fish diversity

A quick post to give a bit of background on the PhD research I am carrying out at present, as always, questions, advice and constructive criticism is welcome.

The vast unknown: assessing the conservation of soft sediment fish diversity

Sand.  That grainy stuff that covers vast swathes of the ocean floor. Although perhaps to the casual observer this habitat isn’t as exciting as coral reefs or seagrass meadows, delve a little deeper and you will discover that there is a whole lot happening out in the vast sandy stretches of the ocean. Sand or soft sediments cover most of Australia’s state and national waters and are heavily exploited by commercial and recreational fishing.

Surprisingly, there has been little research into fish ecology on these habitats, with most effort expended on assessing fish found on coral reefs, rocky reefs, estuaries and seagrass. For a habitat that is so heavily exploited, there is a serious and immediate need to determine the basic ecology of the fish species present, the effects of fishing and also to examine the success of conservation efforts in place. More than 70% of Australia’s marine protected areas cover soft sediments, yet to my knowledge, both nationally and internationally there have been no studies looking at the effectiveness of marine protected areas in conserving soft sediment fish.

My PhD aims to examine the ecology and conservation of soft sediment fish assemblages in temperate waters of South Eastern Australia. Baited Remote Underwater Video (BRUVs) will be used to provide a clear assessment of fish communities found on soft sediments, including in NSW marine park sanctuary zones (no-take zones), habitat protection zones (recreational fishing allowed) and areas outside of the marine park (that are targeted by both recreational fishers and commercial fishing vessels). In addition, I would like to further investigate issues surrounding the movement patterns of some of the soft sediment fishes in these assemblages using acoustic tracking.

Often it has been argued that spatial closures such as marine parks will be of little conservation value over soft sediments as the fish are thought to show little site attachment in this habitat type. It is fairly common to hear people say “they’ll just swim in and out of the reserve and we’ll catch them on the outside”, but is that really true? In contrast to this view, my initial research inside Jervis Bay suggests that blue-spotted flathead (one of the major exploited species found on sand in SE Australia) move less than 500m within a 12 week period of acoustic tracking. Now that might sound like they aren’t moving around much and over the short term that is true, However without longer term data I can’t yet rule out that they that they do roam much further for spawning movements or other seasonal migrations. The next stage of tracking over 18 months will allow me to determine whether or not these longer range movements occur.

bluespotted

Blue-spotted flathead (Platycephalus caeruleopunctatus) ready for release after tagging.

Baited remote underwater video

A frame grab from baited underwater video footage taken in Jervis Bay Marine park showing a Southern eagle ray (Myliobatis australis) and a Eastern fiddler ray (Trygonorrhina fasciata) investigating the bait.

A big thanks to the NSW Department of Primary Industries, Seaworld Research and Rescue Foundation , Australian Wildlife Society  and the Ecological Society of Australia for providing funds and support for various parts of my research.