Archive for April, 2015

WoRMS

Thursday, April 30th, 2015

We seem to have a compulsion to name every species that we notice. Whatever the reasons, such knowledge is increasingly important to us.

For example, is there currently a new, 6th Mass Extinction underway and caused by us? To know how quickly species are going extinct, we have to know what species actually exist.

Elizabeth Kolbert, author of the 2015 Pulitzer Prize for general non-fiction The Sixth Extinction - a terrific and disturbing book (grist'org)

Elizabeth Kolbert, author of the 2015 Pulitzer Prize for general non-fiction The Sixth Extinction – a terrific and disturbing book (grist.org)

This is not always easy, and trying to identify the species that live in our oceans has been particularly difficult. There we have mostly cared about species of commercial interest or unusually large or exotic species, yet most marine species are small, cryptic, buried, and/or in deep water.

And other questions about marine communities also now absorb us: Are marine coastal communities shifting to higher latitudes as the sea around them warms? How does over-fishing, eliminating the top predators, restructure communities? How much does coastal development and pollution modify coastal communities? How are changes in sea currents and temperatures affecting prey species for migrating fish, marine mammals, sea turtles and sea birds?

To even start to answer questions like these, questions whose answers are critical to our own long-term stability and well-being, we need to know what species actually exist, and we need to have confidence in the accuracy of their identification. This requires a lot of energy, patience and expertise.

Enter WoRMS, the fine acronym for the World Registery of Marine Species. For the past few decades scientists have been confirming the identity of all 420,000 marine species that have been described as species since the 1700s. 190,400 turned out to be duplicates – leaving 228,450 legitimate species.

The rough periwinkle Littorina saxatilis lives in the high intertidal of temperate rocky shores, and was known by 113 different names: now just by one (aphotomarine.com)

The rough periwinkle Littorina saxatilis lives in the high intertidal of temperate rocky shores, and was known by 113 different names: now just by one (aphotomarine.com)

Of the legitimate species, 18,000 are fish, 816 are squid, 93 are whales and dolphins, the list goes on and on. Since 2008, 1000 new species have been added to the lists, including 122 species of shark and rays.

The Australian Humpbacked Dolphin Sousa saholensis was recently discovered (marinespecies.org)

The Australian Humpbacked Dolphin Sousa saholensis was recently discovered (marinespecies.org)

That all sounds impressive – but marine scientists estimate that between half a million and 2 million marine species have yet to be described.

We obviously are not going to describe everything before it goes it extinct, though it seems a pity not to know what we’re losing. What WoRMS is offering us though is reliable data, knowledge we can use with confidence as we try to conserve the marine communities that exist and as we try to understand and perhaps mitigate the impact of the global changes that are upon us.

WoRMS is a huge asset. We need to ensure a new generation of experts will be trained to keep the work going.

There is no substitute for accurate knowledge.
For evidence.

The Ruby Seadragon, a new species of a very odd  fish that lives between Australia and new Guinea (marinespecies.org)

The Ruby Seadragon, a new species of a very odd fish that lives between Australia and new Guinea (marinespecies.org)

Older Females as Leaders

Wednesday, April 22nd, 2015

A killer whale pod is a spectacular, complex, cooperative hunting group.

Cooperative hunting as a way of getting food is hard at best, and demands considerable intelligence and a good memory. It has evolved in a few mammals, and among these are killer whales and the closely related pilot whales.

A resident killer whale pod on the coast of BC (bcwhalewatchingtours.com)

A resident killer whale pod on the coast of BC (bcwhalewatchingtours.com)

The theory of natural selection long ago was extended to include cooperative behavior, where individuals could increase their own fitness by helping close relatives. In every case, each hunting group consists of close relatives. As with most animals, adults die not long after they reproduce for the last time, but killer whales, at least in their ‘resident’ eco-morph, are the a remarkable exception: though they are able to reproduce until about 40 years old, and males rarely live much past that age, females may live for decades after the end of their reproductive lives.

Resident pods of killer whales hunt for salmon in the Salish Sea - the coastal interior waters of southern BC and northern Washington (timescolonist.com)

Resident pods of killer whales hunt for salmon in the Salish Sea – the coastal interior waters of southern BC and northern Washington (timescolonist.com)

The best data come from a resident pod that hunts mostly for Chinook salmon in the Salish Sea (BC/ Washington State) and that has been followed intensively since 1976. Every individual and its relationships to all the others in the pod is well documented. Though the age of the oldest female is not definitively known, it is in the range of 103. And that is amazing.

What aid might she and other older females provide to her pod that younger and possibly stronger adults could not more easily provide? An enticing possibility is that older females might be able to provide ecological information about when and where to hunt for fish, particularly in times of environmental stress when fish are hard to find. In hopes of testing this hypothesis, a group of scientists studied pod leadership over the years, in times of both salmon abundance and salmon scarcity. They found that in times of salmon scarcity, older females were more likely to lead the hunt.

When fish are scarce, older females (red in this cartoon) are more likely to lead the hunt to find them (cell.com/current-biology)

When fish are scarce, older females (red in this cartoon) are more likely to lead the hunt to find them (cell.com/current-biology)

This isn’t exactly proof, but it provides tantalizing support for the hypothesis that older females are valued and useful as repositories of ecological knowledge. Of course older females may help the pod in other ways – perhaps assisting others in the pod, mediating conflicts among pod members, providing familiarity with other groups – but these hypotheses are so far too hard to test.

In any case, the more we know about resident pod behavior, including the roles of older, post-reproductive females, the more we can ensure we don’t wreck the ecosystem the killer whales depend on. We should at least be able to do that.

And yes, there is one other species we know of where older post-reproductive females play a critical role in the social success of the group: us. Let’s hear it for grandmothers.

Killerwhales_jumping

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