engineeringecosystems

[engineeringecosystems]

One Hundred and One Shellfish

It is that range of biodiversity that we must care for - the whole thing - rather than just one or two stars. -David Attenborough  

So far, we’ve primarily focused on the “true mussels” in the family Mytilidae. Although most mytilids form reefs (remember umbrella species!) we must remember that they are just another piece in the puzzle of biodiversity, as far as Mother Nature is concerned. Regardless of your views on biodiversity, I reckon it’s best to highlight as many splendid shellfish as possible, in just one post! Strap in ‘cause this one’s a bit of a rollercoaster. 

Staying in the family Mytilidae for a moment, we have some 52 genera. Some of our favorites include the edible mussels of the genera Mytilus (Mytilus edulis, credit: National Science Foundation) 

and Perna (Perna canaliculus, credit Richard Giddins). 

There are mussels that are named after fruits, like the date mussels of the genera Adula (Adula gruneri, credit: Donna Pomeroy),

Arcuatula (Arcuatula senhousia, credit: Graham Bould), 

and Lithophaga (Lithophaga lithophaga, credit: Alchetron), 

the bean mussels of the genus Crenella (Crenella faba, credit: Sarah Gascon),

and the chestnut mussel of the genus Lioberus (Lioberus castaneus, credit: Conchology).

There are adorable (and aptly named) mussels like those of the genera Mytilaster (Mytilaster liteanus, credit: Yuriy Kvach) the dwarf mussel, 

and Xenostrobus (Xenostrobus securis, credit: Caesarion) the little brown mussel - which, along with Crenella faba, measure an isty bitsy ~10mm long at maturity. 

And, drum roll please,

then there are the absolute units, the #metal mussels of the deep sea. These include the genera Bathymodiolus (Bathymodiolus manusensis, credit: J. Hashimoto)

and Gigantidas (Gigantidas haimaensis, credit: Ting Xu). 

Deep sea mussels are wicked: some species can grow to 40cm and, although they filter feed, they actually get most of their nutrition and energy from their symbionts (symbiotic bacteria). Because of the harsh conditions of the deep sea and hydrothermal vents these mussels have evolved to have gills with up to 20x more surface area than their intertidal relatives. These enormous gills allow the mussels to host more symbionts - approximately 1000 billion per mussel! Surprisingly, these bacterial communities are only composed of one or two different types and metabolize either methane or sulfides to produce organic carbon which the mussels can use for energy. 

Anything that lives in the deep sea is alien life on Earth. These mussels are an example of how similar organisms can fill many different niches (ecological roles) depending on their habitat. If you want to read more on deep sea mussels here’s an easy article.

Annnnd there are “mussels” that aren’t even mussels? 

Yes, you read that right. 

And, yes, I am just as confused as you are, because remember the family Mytilidae are the “true mussels”. Scientists, I demand an explanation!

To make nomenclature that much more fun (I mean confusing) there are several mytilids which have been given the name “clams”, including the genera Adipicola, Idas, Modiolarca, Mytella and Septifer (Adipicola osseocola below, credit: Museum of New Zealand).

But the fun doesn’t stop there!

The freshwater zebra mussel is in an entirely different family, Dreissenidae (Dreissena polymorpha below)! Despite their common name they actually aren’t even closely related to true mussels and are closer in relation to some clams.

Hopefully by now you’re starting to realize why common names aren’t the best. 

Leaving the mytilids behind, let’s explore some other bang-up bivalves. 

Coming in with the largest living bivalve is Tridacna gigas the giant clam (credit: Tokoriki diving). 

These fellas are MASSIVE, weighing in at more than 200kg (440lbs), with the largest recorded individual estimated at 250kg! They have mantle openings so big that you could fit your head inside (definitely do NOT). Giant clams are a popular attraction at my local research station and I always find myself checking them out at the end of data collection; apparently some kid at my school got his foot stuck in one while on a research trip - yikes. Their conservation is particularly important as they are a food source for Pacific Islanders as well as their massive shells being sought after for international trade. 

The smallest living bivalve is also a clam Condylonucula maya measuring less than a millimeter in length. How cool is it that both of these organisms are bivalves, clams even, yet their sizes are at opposite ends of the spectrum?  

Fun Fact! Did you know that some bivalve molluscs have eyes, like Agropecten irradians the Florida Bay scallop? Scallops, in particular, can have 100 small blue eyes like those in the photograph below (credit: David Moynahan). 

There are really weird looking bivalves, like Teredo navalis the naval shipworm, whose shell is really small compared to its body size (you can see the shell at the very end of this burrow, to the left, credit: Maggie Ho). As you can guess these guys can cause some pretty serious damage to ships. 

To really round this craziness up there are organisms that look very similar to bivalves but are in an entirely different phylum, Brachiopoda (remember bivalves are in the phylum Mollusca). When unrelated organisms are subject to the same selective pressures, like accessing a particular food source, they typically evolve similar adaptive traits. This process is called convergent evolution and it’s actually pretty common in the animal kingdom (like flying in birds and bats) and it is always cool to see how two completely different organisms evolve similarly despite coming from different parts of the Tree of Life. 

In the diagram above you can see how the plane of symmetry is different between brachiopods and bivalve molluscs, which is a good way to distinguish them (credit: skeptical squirrel). 

With well over 10,000 described species of bivalve I could easily go on, and on. And on. Seriously we’d be here forever. But this has already been a very long post, so heaps thanks for making it this far! This post also wraps up the identification portion of this conservation blog. Coming up we will have some history lessons and shellfish-story-times before wrapping up with aquaculture and restoration. 

But seriously, thank you to everybody who’s been reading my posts and reaching out. It’s crazy to know that people all over the world are reading my blog. I definitely learned a shell-load making this post! I hope you enjoyed the craziness and learned some cool new facts. 

What’s been your favorite shellfish so far? Ostrea (the oyster from my first post) is still top 3 for me, but scallops with eyes?! Come on, that’s awesome.

[engineeringecosystems]

One mussel, two mussels, brown mussels, blue mussels

Walking through a meadow calling the plants by name is like entering a room of friends instead of strangers. -John Hildebrand

Taxonomy is the science of classifying organisms based on their shared characteristics. Although we probably started purposefully grouping things together around the same time that we developed language, the first physical record of classification dates to around 3000BC in China, with the Father of Chinese medicine, Emperor Shen Nung. It wasn’t until the 1700′s when a Swedish botanist came along and developed the system of classification that we use today. Known as the “father of modern taxonomy”, Carolus Linnaeus dedicated his career to classifying plants and animals (and minerals). Carl’s catalogue was a continuous piece of work, constantly being added to and revised as he identified and classified new organisms. In 1758 Carl published the 10th edition of his massive taxonomic collection in a book titled Systema Naturae - and I mean truly massive, by its 13th edition it was 3000 pages long! 

With the introduction of animals, the 10th edition of Systema Naturae is widely accepted as the start to “modern” taxonomy. Carl classified organisms into a hierarchy - which we know as the Tree of Life. From trunk to leaf, least to most exclusive, it goes: kingdom, phylum, class, order, family, genus and species. Carl also developed and popularized the use of binomial nomenclature which shortened long-winded Latin names down to two terms, the first denoting the genus and the latter the species. However, circumstances of the time heavily influenced Carl to describe the world as created by God which led him to classify organisms based on morphological features, such as the shape, size and placement of bones in a skeleton. This was very helpful at the time because until then we thought whales were fish! But, as technology has progressed, especially in the field of genetics, we began to learn that just because two organisms look alike or behave in a similar manner doesn’t necessarily mean that they’re the same organism, or even closely related, if at all. This, of course, led to a reorganization of Carl’s work (and occasionally to the dismay of stubborn scientists). If you’re keen to learn more about Carl or taxonomy check out this video.

As useful as it is, identifying and classifying organisms can get a bit overwhelming, especially when everything looks the same (yeah, I’m talking about you mussels!). I am going to do my best to break this post down into bite sized pieces. So, without further ado, lets classify some mussels.

I figured it’s probably best to start with the common blue mussel, Mytilus edulis (credit: British Antarctic Survey), first described by Carl in 1758. 

Quick shell fact: although all Mytilus edulis, the shells above are from high to low latitudes (left to right) and show subtle morphological changes due to environmental factors like temperature and salinity.

Despite looking like a rock (there, I said it first so you don’t have to feel bad), Mytilus edulis is an animal, and therefore in the kingdom Animalia. Like many members of the phylum Mollusca, from squids to snails, Mytilus edulis has a radula, a mouthy bit that creates a current drawing in water and food, a fleshy covering that holds their body together called a mantle, and a shell made mostly of calcium carbonate. Mytilus edulis has two shells, or valves, which are held together by a strong muscle called a foot (which also makes them so dang hard to open and eat), situating it among others like clams, scallops and oysters, in the class Bivalvia. We are first introduced to the “true” mussels in the order Mytilida, which are characterized by having long asymmetrical shells covered by a thick, adherent layer of “skin” called the periostracum; they attach themselves to solid substrate, like rocks, rope, or piers, using a secreted bundle of filaments, referred to as a byssus or byssal threads. The only extant (not extinct) family in this order is the family Mytilidae which contains some 52 genera. One of these is the genus Mytilus which contains most of the edible marine mussels. Finally, we arrive at our friend the common blue mussel or the Atlantic blue mussel, known by its species name Mytilus edulis.

And there you go. 

Mytilus edulis occupies the coasts of the North Atlantic, including the United States and Canada, as well as France and the British Isles across the pond. When its range overlaps with others in its genus, like Mytilus galloprovincialis in the Mediterranean or Mytilus trossulus in the northern parts of the North Atlantic, Mytilus edulis will sometimes form a complex and hybridize with them. 

Other members of the genus Mytilus include:

Mytilus californianus, the California mussel (credit: Sharon Mollerus)

Mytilus coruscus, the Korean or hard-shelled mussel (credit: Conchology, Inc.)

Mytilus galloprovincialis, the Mediterranean mussel (credit: Andrew Butko)

Mytilus planulatus, the Australian blue mussel (credit: Javier Couper)

Mytilus platensis or chilensis, the Chilean blue mussel (credit Schnecken & Muscheln)

and Mytilus trossulus, the bay or foolish mussel (credit: Conchology, Inc. ).

I imagine many of you are looking at these mussels and thinking, “yeahhh uhhh Matt, they all look like the same”. Maybe with this face

(or maybe even this one).

But stay with me. 

You’re right, they do look very similar, which is why classification can be troublesome when it’s based off how an organism looks. Classification based off morphological features can be useful, but up to a point, and may be useless at finer-species level-scales. But advances in science and technology have led us into the new age of taxonomy - classification based on genetic sequencing, using a technique called Polymerase Chain Reaction or PCR.  Like reading a recipe, scientists can sequence the genome of an organism and reveal hidden secrets like the evolutionary age of an organism, which can help us construct a more accurate representation of the Tree of Life. Along with advancements like data storage, genetic sequencing has revolutionized the way we classify organisms. And it’s showed us that there is in fact a difference (albeit small) between the members of the genus Mytilus. 

I hope you learned a lot this week! I really enjoyed putting this post together, even though I didn’t cover all the mussels that I wanted to. And I know I promised y'all last week that we would visit the some of the deepest parts of the ocean and we will! Next week will be less lecture and more *let me show you all the pictures of my children that you didn’t ask to see*. Until then, try to be a little less selfish and more shellfish. Cheers, y’all!

[engineeringecosystems]

Of Mussels and Men

I got you to look after me, and you got me to look after you, and that's why. -John Steinbeck

When you think of conservation what comes to mind?

Probably any one of the charismatic critters like polar bears, whales, sharks and sea turtles, the list goes on. These fellas are definitely worth saving not only because humans are to blame for their decline, but I'm afraid to tell you that (*whispers off to the side*) single-species conservation is not always the most beneficial to a community or ecosystem. A professor of mine likes use the term “bauble conservation” because as humans we have a tendency to conserve iconic species that are special to us in someway, like baubles on a Christmas tree; but without the tree...oi, I think you know where this is going.

The Yale School of the Environment published an article discussing the need for and efficacy of the conservation of umbrella species, like the sage grouse of the American West (photographed above by Dave Showalter). *Holding back my laughter* I recommend watching “the dance of the sage grouse” on YouTube because I can’t in good conscience link it here. To highlight the article, though,

it’s the idea routinely advocated by conservationists that establishing and managing protected areas for the benefit of one surrogate species — from gorillas to grizzly bears — will also indirectly benefit a host of other, less charismatic species sharing the same habitat. 

and that, 

the species that stand out to human eyes don’t always turn out to be the best umbrella species for their habitat.

I’m not claiming that the above mentioned ‘charismatic critters’ were intended as umbrella species. Nor are umbrella species the cure-all to conservation. As mentioned in the Yale article, the umbrella species-conservation approach can sometimes leave holes in terms of ecosystem protection by unintentionally excluding a particular group of organisms. Nonetheless, I believe that the umbrella approach to conservation should always be considered, especially when drafting governmental legislation. It isn't just the polar bears and whales that need our help - it’s the trees and the bees and all manner of creepy crawly things on this planet. 

And it’s the shellfish. 

Before we dive in to mussel conservation, let’s have a quick brief about shellfish. 

Mussel is a common name for members of several families of bivalve molluscs. 

Molluscs make up the second-largest phylum of the Kingdom Animalia. This phylum consists of invertebrate animals (they ain't got no spine) including snails and slugs, cephalopods (squids, octopuses, and cuttlefish) and bivalves.

Bivalves are molluscs enclosed by two hinged shells (pictured below). While all bivalves are shellfish not all shellfish are bivalves - just know that for this blog I will use them interchangeably. 

Mussel is frequently used to refer to marine bivalves in the family Mytilidae. 

I will be referring to various types of mussels by their scientific names next week. For example, Mytilus edulis is the scientific name for the common blue mussel. 

Using binomial nomenclature (the use of two terms, usually in Latin, to denote the genus and species of an organism) is good practice for identification as (1) common names can be used for a variety of species (even from different genera!) and (2) the same species can have different colloquial names. I will continue to refer to scientific names throughout this blog, so keep track of them - we’ll play bivalve bingo later! 

*Classifying organisms can get a bit confusing. You may be able to list some examples of species but there are also families and classes and other levels of classification which can group seemingly unrelated organisms together. Don’t get too wrapped up in the terminology right now, we will go over it in detail next week.

Like oysters, mussels are incredibly effective at filtering water (check out the video below). Although filtration rate can vary depending on factors like mussel size and water quality, estimates suggest that in good conditions a single adult mussel can filter upwards of 50 liters of water a day! This powerful filtration system helps keep estuaries and coasts healthy by filtering out suspended particles (like plankton) and trapping nutrients from terrestrial runoff, inlcuding chemical contaminants. Together they can transform a muddy bay into a thriving community, simply by being there. Mussels also act as ecosystem engineers by creating reefs that serve as nurseries for fish larvae, refuge for juvenile fish, invertebrates and other creepy crawlies, and increase the presence of additional bivalves and fish. These attributes make them an excellent example of an umbrella species (photographed below by donieve). 

If you just learned something new about mussels - great! 

But, we (yes even the scientists) have much much more to learn about these splendid shellfish. Next week we will explore the diversity of mussels around the world (even in the harshest spots in the ocean!). Because we still have so much to learn about mussels (wishin’ we had done that global review earlier, haha) we will also be discussing the history, cultivation, destruction and restoration of other shellfish reefs over the next few weeks (we’re going to visit old mate, Ostrea angasi).

[engineeringecosystems]

Won't stop me though! 

When I comb the beach my friends say I look like an old man because I’m bent over with my hands behind my back haha!

[engineeringecosystems]

An Invitation to Conservation

Where most people see a rock I see potential.

Oi mate, how ya goin? 

My name is Matt and I am an international postgraduate student studying marine biology at James Cook University, in Townsville, Australia. The photo below was taken during my first semester when my friend and I visited the Whitsunday Islands, off the coast of Queensland. We raced a rain cloud back into the marina with our sailboat - it was wicked. We lost the race but ultimately won this sweet photo (see smiles below). 

I received my Bachelor’s degree in Marine Biology and Environmental Policy from Rutgers University, the State University of New Jersey (my home--RU RAH RAH!). While at Rutgers I was initiated into Alpha Zeta, the Co-Ed Honours and Service Agricultural Fraternity of the School of Environmental and Biological Sciences (a mouthful). During my time in Alpha Zeta I developed leadership and professional skills while proudly serving my school and community. I also very much enjoyed my time as an ambassador and tour guide for my school.

During my last semester at Rutgers I was accepted into James Cook University and moved to Townsville shortly after graduating. While at JCU I have had some pretty sweet hands-on experience (like raising juvenile grouper!) and I have sat in on lectures given by some of the leading scientists in my field.

To complete my degree I am carrying out my placement (internship for my Americans) under the supervision of Dr. Ian McLeod at TropWATER. TropWATER is an Australian research group dedicated to undertaking research in fields related to water science, resource management and the ecology of water ecosystems, with a focus on sustainability. In addition to this blog, I am working with Dr. Jennifer Hillman on a global mussel review which aims to create a necessary global assessment and database of mussel beds. This assessment is the first to focus on mussels and will help support future research regarding restoration and conservation. The primary stream of content on this blog will thus be related to mussels. Together we will explore their diversity, ecological roles, destruction and restoration (*whispers* I’ll surely be sneaking other shellfish in along the way, hehe).

My interest in conservation started with Ostrea angasi (photographed above by Richard Cornish). While working on a small project for a coastal ecology class I came across this article about the largest oyster reef restoration project in the Southern Hemisphere (and second largest in the world after the United States). The University of Adelaide and The Nature Conservancy partnered up to complete the project and added 20 hectares (200,000 sq. meters!) of Australian flat oyster spat and recycled oyster shells to historic reef sites in the Gulf of St. Vincent (photographed below by Anita Nedosyko).

I learned just how important oysters are to the health of our estuaries and coasts, and to our communities (economically and socially). Shellfish are an important protein source for millions who depend on ocean resources and are also a very lucrative aquaculture industry because of their pearls. Much like coral reefs, oysters form three-dimensional reefs that serve as a habitat for a variety of fish and invertebrates. Oysters are known as ecosystem engineers because, in addition to creating habitats, they also filter water, stabilise shorelines, and serve as nurseries for several fish species (an ecosystem engineer is any organism that creates, modifies, maintains or destroys habitats. The North American beaver is a classic example of an ecosystem engineer). 

My research also reminded how greedy and destructive humans can be. In Australia native oysters have been harvested to functional extinction; this means they are not abundant enough to preform many of their ecosystem services. Before European colonisers reached (what is now) Australia oyster reefs used to dominate the southeastern coastline of the continent. It is estimated that historic oyster reefs stretched some 1500km (that's two-thirds of the length of the Great Barrier Reef!). Oysters were harvested so heavily that their populations were reduced to less than 1% by the beginning of the 20th century.

I was so inspired by the Adelaide oyster restoration and its role in the environment and the community. I hope that these blog posts (carefully crafted with love and passion) inspire you to be a little less selfish and a little more shellfish. 

If you want to learn more about Adelaide’s oyster restoration (and the little fella that started it all for me) then check out the video below. 

[engineeringecosystems]

It seems like almost every marine biologist has a fish-or-ocean-related tattoo. Many have sharks, some have turtles...and I...have an oyster. 

[engineeringecosystems]

I have always been amazed at how the world works and how it is connected. Like how a rock can be smoothed down by a river flowing to the sea. And how a salmon can (somehow) swim up that same relentless river.

MJH