Thriving Oceans

Here are a couple of very short clips of an octopus that I encountered in Hawaii.  And I think they showcase the amazing capabilities of this incredible marine species in regards to changing color.

My sea turtle hazard is worse than your sea turtle hazard. 

Of course.  

Sounds logical. 

And more importantly it falls within that quirky social dynamic called HUMAN NATURE.  But the results of bias within the scientific community is an interesting topic; especially when you add the sea turtle variable and the number of threats plaguing the seven species.  So put any preconceived notions that you may have aside and let’s see if we can all come together and accept the fact that the hazard I’m researching poses the greatest threat to sea turtles.

Well, perhaps we should turn to the experts and listen to what they have to say.  And that’s exactly what the authors of a new publication, Using Expert Opinion Surveys to Rank Threats to Endangered Species: A Case Study with Sea Turtles, in Conservation Biology did.  And should we really be surprised by the findings?

An internet-based survey was distributed to sea turtle experts that was designed to determine the respondents’ overall experience, expertise and the proficiency in regards to particular species, geographic regions, and hazards.   Hazards that included pathogens, direct take, global warming, nest predation, pollution, coastal development, and fisheries bycatch.  After quantifying results spanning the nonprofit sector, government agencies, and respondents in over 100 counties, a pattern began to emerge.  A pattern attributed to expert bias.

“Respondents with no experience with respect to a sea turtle species tended to rank hazards affecting that species higher than respondents with experience.  A more-striking pattern was with hazard-based expertise: the more experience a respondent had with a specific hazard, the higher the respondent scored the impact of that hazard on sea turtle populations.” 

Perhaps a sign of the times, everyone was in agreement that sea turtles were under threat from multiple anthropogenic hazards.   It also became apparent that there was an overall consensus on the greatest hazard, fisheries bycatch.  The survey found:

• Bycatch was ranked as the top hazard for 18 sea turtle populations.
• Coastal development was ranked as the top hazard for six populations.
• Nest predation was the top hazard for three populations.

Interesting!  And I guess that exclamation warrants further development if I expect it to make any sense.  Although bycatch, a pelagic threat, ranked as a top hazard for 18 populations, a disparity still exists between coastal development and nest predation, which are terrestrial and coastal threats.  The amount of invested resources does not correspond to the highly scored pelagic threat. 

The authors point out that, “Twenty-eight percent of survey respondents reported conducting research or activities focused in the pelagic environment, compared with 70% who conducted research in both terrestrial and coastal environments.”

Which rounds off the discussion as to its applicability to conservation.  Should statistical methods that account for expert bias be implemented by conservation planning programs?  And should hazards that are both highly scored by experts and have a high uncertainty in regards to the range of effect on a population be treated as a research priority?

 Well one thing is for certain and I agree completely with the authors that, “Priority setting for the conservation of threatened and endangered species cannot wait for exhaustive empirical research.”

DONLAN, C., WINGFIELD, D., CROWDER, L., & WILCOX, C. (2010). Using Expert Opinion Surveys to Rank Threats to Endangered Species: A Case Study with Sea Turtles Conservation Biology DOI: 10.1111/j.1523-1739.2010.01541.x

As a follow up to my May 28th post (Proposal to save whales means lifting whaling ban and sanctuary harpooning) and interview with Chris Cutter of the IFAW, I thought I’d share the latest news on the issue…

(Agadir, Morocco – 23 June 2010) – The International Fund for Animal Welfare (IFAW – www.ifaw.org) announced today that a controversial proposal to legalize whaling has failed at the annual meeting of the International Whaling Commission (IWC) in Agadir, Morocco.

“Under a cloud of corruption allegations the IWC is taking a safe course, opting for a cooling off period that protects the moratorium and other IWC conservation measures,” said Patrick Ramage, Director of IFAW’s Global Whale Campaign. “Had it been done here, this deal would have lived in infamy.”

The proposal, three years in the making, proposed a compromise between whaling and non-whaling nations which regularly clash at annual IWC meetings. Among the most hotly debated components of the proposal was a plan to overturn the worldwide ban on whaling, in place since 1986, by allowing legalized hunting of whales by Iceland, Norway, and Japan – the last three countries still hunting whales commercially. Japan, Norway, and Iceland have illegally killed nearly 35,000 whales since the inception of the moratorium.

“This was an intense three year effort but one conducted behind closed doors and focused on defining terms under which commercial whaling would continue rather than how it would end,” said Ramage. “The proposal it produced could not withstand public scrutiny and ignored the overwhelming global support for permanent protection for whales. Any future process of negotiation should not leave the views, expertise, and perspective of the global NGO community sitting outside.”

Our planet is an intriguing concoction of variables that meld together for successes spanning the organization of life (species, populations, communities, and ecosystems).  It is literally an evolutionary process that is ecologically driven.  And as a genotypic sex determined species, we seem to have an inherent fascination with the mysterious adaptive significance of environmental sex determination.  But the evolution of environmental conditions, such as temperature, determining the sex of offspring is not what is going to be explored at this time.  Nor do I plan to open up a heated discussion about climate change.

However, I am curious about the population dynamics of species exhibiting temperature-dependent sex determination in a warming world.  More specifically, how will sea turtle populations fare if sex ratios are dramatically skewed as a result of warmer temperatures.  Yet worry not as I am not alone in wondering about the stability of our threatened and endangered sea turtles.

Scientists from the Institute of Life Science, Institute of Environmental Sustainability and the National Marine Park of Zakynthos executed a study to determine if “temperature-dependent sex determination increases the probability of extirpation when ambient temperatures induce the production of offspring of a single sex.”  Especially when, “Some taxonomic groups, such as sea turtles, are already endangered and have sex ratios skewed to the sex produced at warmer temperatures (females).”

However, measuring population viability is more than just determining the ratio of male and female hatchlings.  Species stability requires a measurement of the number of males and females that are ready to mate at any one particular time (operational sex ratio), which also accounts for the breeding frequencies of each sex.

Results:

• Based on hatchling ratios, it is assumed that for every 100 adult turtles in the population, there were 70 females and 30 males.
• Males return to breed every year
• Females breed every 2.6 years
• Operational sex ratio is 47% female – in any particular year 30 out of 30 males will be breeding, but only 27 out of 70 females will breed.

So just what does this data all mean?  Well, the most striking finding is that since male sea turtles breed more frequently than females (i.e. an operational sex ratio that is not female biased), they are able to “reduce the probability of unfertilized clutches.”  Even though males already comprise a smaller portion of the population, and would do so to a greater extent in a warming climate, the results are indicating that we (or they) do not have much to worry about when it comes to temperatures altering the sex ratios to a point where the population collapses.  But perhaps this just might be limited to the SHORT-TERM.

As pointed out by the authors, a male breeding cycle that is 2.6 times greater than females may help alleviate the impacts of climate change on the population, but there will undoubtedly be a reduction in males over time.  And as males become limited the probability that a population will persist declines.

For example, it is predicted that under some climate-change scenarios, nesting beaches in some parts of the world will produce only female hatchlings.  If this hatchling sex ratio propagates into adult sex ratios (e.g., there is no immigration of males from other sites), then the increased breeding frequency of males will be redundant because there will be no males.

Thus, we just may find ourselves taking on the role of the Earth’s climate by relying upon methods to control nest/embryonic temperatures in an attempt to artificially produce male hatchlings and ultimately prevent the loss of sea turtles.

HAYS, G., FOSSETTE, S., KATSELIDIS, K., SCHOFIELD, G., & GRAVENOR, M. (2010). Breeding Periodicity for Male Sea Turtles, Operational Sex Ratios, and Implications in the Face of Climate Change Conservation Biology DOI: 10.1111/j.1523-1739.2010.01531.x