sarahkeenihan

Posts Tagged ‘New Zealand’

A window to the ocean

In December 2013 on December 11, 2013 at 8:10 pm

bivalve blisters

KirstiWaves. We catch them, ride them, jump into and over them. Play in them, marvel at them. They are a source of awe for photographers, surfers, sailors and coastal people around the globe.

And they are vehicles, transporting what resides in the ocean onto the shore. Waves dump clues to an underwater world all along the coast, for us to decipher; connecting us to invisible ecosystems.

My recent sleuthing involved the shells of these bivalves (above). All along the beach at Home Bay in Auckland were these shells with holes and scrapes across their outsides. My guesstimate was that 1 in 3 shells of this type looked like this.

So as you do, I Googled it. Unfortunately, my key words weren’t what Google was looking for.

I loved marine invertebrate biology at uni, and I remembered that moon snails are predators of bivalves and drill holes in bivalve shells to get to their soft insides. But the holes they drill are neat and round, not dragged across the shell like someone was hauling a dead body over it. Then just last week at a conference, I saw a woman who was my invertebrate biology tutor from undergraduate years – and she’s a snail person! She said they reminded her of teredo worm holes in wood.

So off I went on another search. But these teredos don’t burrow into shells, just wood when they are ready to metamorphose from a planktonic larvae into a tunnelling clam….. HANG ON – a burrowing clam that’s called a worm?!?! A clam whose body resembles a worm but it has two shells at its front end designed to burrow into wood. So here I am, on a marine invertebrate bender. Loving it, and frustrated that the clues I were given are sufficiently cryptic to keep me searching until I find the answer.

Sarah: When I read Kirsti’s post, and saw her image, I too was inspired to find an answer. Having interviewed Thierry Laperousaz  (Collection Manager, Marine Invertebrates at the South Australian Museum) earlier in the year, it occurred to me he might be just the man for the job. A quick email with photo resulted in the following:

These are called mud-blisters made by burrowing marine worms most probably of the Spionidae family.  They can have an negative impact on bivalves population in case of severe infection.

Further reading told me that Spionidae worms are found all over the world, and occur in both shallow and deep waters, and even above the tidal line, particularly along sandy beaches. Some but not all of the species bore into shelled bivalve molluscs; those that do can cause blisters as shown in Kirsti’s image.

If you have more information which will assist us in identifying the particular worm involved, please be in touch!

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And speaking of poo…

In November 2013 on November 30, 2013 at 8:48 pm

Kirsti honeydew Ultracoelostoma Noble text

Kirsti: Earlier this week, Mia wrote about POO POWER! I too have a story about the science of poo.

Lots of insects feed on phloem, a.k.a. plant sap. And just as we excrete waste from an omnivorous diet as a conglomerative breakdown of those foods, sap-sucking creatures such as scale insects, aphids, psyllids and others  poo honeydew, the waste from the sugar-rich foods they ingest.

Even further down the food chain exist microbial communities that survive on the honeydew (poo) that makes its way down onto the surface of leaves, which are little ecosystems in their own right. If you live there, you live in the phyllosphere!

We don’t know that much about life in the phyllosphere. But recently some scientists in New Zealand looked at fungi from the phyllosphere of native beech forests in New Zealand. Endemic scale insects that live on these trees produce up to 4500 kg  dry weight/ha/year of honeydew.

The insects use an ingenious method to keep themselves clean and minimise fungal growth on their bodies:  the honeydew is flicked off the end of an anal wax-tube (as shown in picture).

Together, all the excreted sugary delights from these creatures  fuel the growth of an abundant mould. The mould appears black and kind of powdery from afar, with human eyes. But look closer – a LOT closer, down a scanning electron microscope then even closer at their genes – and you will see a circus of species, a kaleidoscope of colour, most of which cannot be identified!

The study that identified these fungi communities in New Zealand emphasises that despite the sooty mould being such a ubiquitous element in the scale insect-beech system, we know very little about the microbial diversity. The conference I have just been at highlighted the same gap in knowledge for ecology in general.

So people, let your imaginations run wild! Poo of all sorts of species powers communities, even if it’s a microscopic one in the phyllosphere.

Oh, if you’re interested in microbial communities supported by your own body, I’d highly recommend reading The Wild Life of Our Bodies by Rob Dunn, a fantabulous science writer from North Carolina State University.

[image thanks to David Noble]