Seahorses: On the Decline

Pair of pygmy seahorses.

Every year, more than 150 million seahorses are collected in the wild and dried for use as souvenirs or medicines.  The wild populations of seahorses are becoming depleted, and many species face the threat of extinction.  According to the most comprehensive inventory of the global conservation status of plants and animals, the International Union for the Conservation of Nature’s Red List (IUCN), 38 species of seahorses are on the list: one as Endangered, seven as Vulnerable, one as Least Concern, and 29 as Data Deficient.  The seahorse population has declined by 20% over the last 10 years (or three generations).    

            There are three major reasons for the decline in seahorse populations: the Traditional Medicine trade, the curio trade, and the pet trade.

Thousands of dried seahorses.

            Hundreds of thousands of captured wild seahorses are used in the Curio trade.  Seahorses are sold as key chains, earrings, paperweights, and novelties in shops for the tourist trade.  Many people don’t realize that they are buying dried animals that were once living in the wild.  
            Approximately 95% of the wild seahorses that are collected are used in Traditional Medicine, especially in Asia and Asian communities.  Seahorses are sold whole and dried or ground for use in tonics and prescription medications.  Seahorses are used to treat asthma, respiratory disorders, sexual dysfunctions, broken bones, and heart ailments.  

Seahorses also fall victim to aquarium hobbyists in the pet trade.  Up to one million seahorses are collected for the aquarium trade every year.  The process of catching the seahorse, packaging it, shipping it, and selling it can take weeks.  By the time the seahorse arrives to a home aquarium, the animal is starved and stressed, which usually results in its demise.         

            Seahorses need to be preserved for ecological, biological, economic, and medical reasons.  Seahorses are important predators, and removing them may disrupt ecosystems.  Their reproductive ecology is important and provides us with a unique opportunity to expand our understanding of reproductive biology: only the male becomes pregnant and most pairs are monogamous.  Seahorses also provide some fisheries with a substantial amount of income in addition to being used to treat a wide range of medical conditions and ailments. 

Project Seahorse, an organization led by biologist Dr. Amanda Vincent, works worldwide to monitor trades, establish protected marine areas, and continue research on seahorses to determine what conservation measures are needed to protect seahorses.

Seahorses are a flagship species for a variety of marine conservation issues.  Seahorses are charismatic symbols of the sea grasses, mangroves, coral reefs, and estuaries.  Protecting seahorses means protecting all of the diverse habitats within our oceans and saving our seas.   

Resources

Project Seahorse

The Seahorse Trust

Shedd Aquarium: Seahorse Conservation

Save Our Seahorses

Clownfish: Twisted and Confused

"Clownfish and Anemone"

One of America’s most famous and adored marine fish, the Clownfish, may be even goofier than their name suggests.  These cute orange and white fish that we have grown to love, thanks to the Disney movie “Finding Nemo”, actually live a very twisted sexual life.  You see, the clownfish is hermaphroditic, meaning that they can play the role of both male and female fish.  Although this seems very strange to us humans, it is actually a fairly common practice in the aquatic world. There are said to be as many as 21 families of fish that behave in this kinky manner (Stephens). I don’t know about you but that makes me think twice about the cleanliness of the ocean we swim in.

The clownfish specifically is known as a protandrous sequential hermaphrodite, not to be confused with the protogynous sequential hermaphrodites.  To break this down, sequential hermaphrodites are those which “develop as one gender before changing to the other gender” later in life (Cooney).  Of the sequential hermaphrodites there are the two types.  The protandrous start out as males and can later switch to females, while the protogynous develop as females first and then switch to males.  So let’s tie this all together in terms of the clownfish. 

Imagine you are a clownfish that just hatched from its egg.  You start off life as an undifferentiated male with just your mom and dad around.  Sadly, something happens to the mother and she’s gone which just leaves you and your dad living in this small hypothetical population.  In the name of procreation your dad changes into a female to allow for spawning.  As if it isn’t weird enough, you now must breed with your female father to start a new generation.  This happens and a new generation of undifferentiated males is hatched.  Tragically, after the spawning season is over a shark swam in and ate the father! Being the oldest male you take a long look around and find that there aren’t any clownfish ladies swimming around and thus it becomes your turn to become a female.  This is the reproductive behaviors of the clown fish and in general for any sequential hermaphrodite (Cooney). 

Image from Cooney

Although this seems very strange to us humans who don’t naturally change genders, it is both commonplace and beneficial for these fish.   For a small clownfish, it is a truly a “fish-eat-fish” ocean out there.  Living this type of hermaphroditic lifestyle ensures that there are always both male and females around to safeguard the population density.  

If you are still baffled by how these fish reproduce (don't worry its so foreign to us that it is not an easy concept to grasp) then check out the short video below. It does a great job at displaying how the clownfish changes sex and reproduce. 

References:

BeckmanInstitute. “Sex-Changing Clownfish.” Online video clip. YouTube. YouTube, 27 September 2012. Web. 23 February 2014.

Chow, Samuel. Clownfish and Anemone. 7 October 2010. Ask Nature. Web. 23 February 2014.

Cooney, Patrick. “Finding Nemo Lied…” The Fisheries Blog.” The Fisheries Blog.com Web. 18 February 2014.

Stephens, Christina. “List of Hermaphrodite Animals.” Animals. Demand Media. Web. 18 February 2014.

The Mantis Shrimp

photo from chicagonow.com

Kingdom: Animalia

Phylum: Arthropoda

Subphylum: Crustacea

Class: Malacostraca

Subclass: Hoplocarida

Order: Stomatopoda

(dept.lamar.edu)

The Mantis Shrimp- very beautiful to look at, but a complete terror in the marine world.

The Mantis Shrimp can be found in shallow waters off the shores of Palos Verdes and Catalina Island in southern California (Cabrillo Marine Aquarium). They are carnivores, and a deadly predator to other marine animals; they hunt for prey by means of stalking and sneak attacks as well as burrowing and waiting motionless for their prey before they snatch them. The Mantis Shrimp's diet includes small crustaceans, snails, clams, and fish.

Mantis Shrimp are not shrimp at all- they're crustaceans. They get their name only because they look like both a praying mantis and a shrimp. Their average size is about 12 inches in length. Reproduction varies among Mantis Shrimp. Some are monogamous, but most are polygamous. All Mantis Shrimp reproduce by sexual reproduction. This is initiated when a male Mantis Shrimp does a courtship fane to let a female know his intentions. (dept.lamar.edu) When they come together, the male will transfer sperm to the female. The female can then choose to retain the fertilized eggs, immediately lay the eggs in her burrow, or keep them on her forelimbs.

There are two characteristics of the Mantis Shrimp that I really want to get down to, though- their eyes and eyesight, and their incredible strength behind their punch and attacks.

photo from National Geographic - Italy

First their eyes and sight. As you may know, humans have three types of color receptive "cones". These cones are green, blue, and red; the red cone allows us to see red and colors derived from red- like orange when yellow is added to red, or purple when blue is added to red. (The Oatmeal) Knowing this, imagine having TWELVE to TWENTY-ONE photoreceptors! ALL OF THE COLORS! According to an article by Sebastiaan Mathôt, he says that the upper and lower parts of the eye are like the typical compound eye, but it's the Mantis Shrimp's midband that gives the crustacean their incredible ability to see so many colors. However, even though Mantis Shrimp have the ability to see many different colors, they are TERRIBLE at distinguishing color differences. In the article written by Mathôt, he goes on to explain that scientists have done color discrimination tests on Mantis Shrimp to test their vision. This included using two optical cables in an aquarium that produced color; the crustaceans were trained so that they picked the cable with the specific color (and then they were rewarded with food!). The experiment showed that when the colors were very different, their task proved easy; when they were very close in color, the task proved hard. So it was concluded that Mantis Shrimp can only differentiate between colors that are about 12nm apart... humans can distinguish color differences as small as 1nm. (Awkward...) What a wasted talent! ...Maybe they're just overwhelmed with how many colors they can see. In all seriousness, there are many possible reasons for this, so I would definitely check out Mathôt's article, here, to read more on why the Mantis Shrimp have such trouble using their crazy color sight ability.

photo from UCMP Berkeley

Now onto their terrifying boxing gloves of appendages they have. You should ALWAYS take these little dudes seriously. Mantis Shrimp have what's called raptorial appendages on the front of their bodies; you can think of these like arms, if that helps. They can move these appendages extremely fast- two milliseconds, to be exact. (UCMP Berkeley) To put that into perspective, a blink is 100 milliseconds... but I wouldn't suggest blinking if you know one of these guys is stalking you. The other part of this appendage is what they call a "smasher", and they're freakishly powerful. (HULK SMASH!) Mantis Shrimp use this club-like part of their appendage to completely annihilate any animal with a hard shell. In fact, they can smash so hard, hard shells snap like butter being split by a knife. (Scared yet?) Get this: if their smasher was the size of a human fist, the force of its punch would be equivalent to a twenty-two caliber rifle (UCMP Berkeley); so, in other words... you're dead. If that's not a good comparison for you: a Mantis Shrimp can strike prey with 1,500 Newtons of force; if humans could throw at only ONE-TENTH that speed, we would be able to throw a baseball into orbit! (The Oatmeal)

There's more about their color vision and power punch in a great comic strip on The Oatmeal website. Check it out here: http://theoatmeal.com/comics/mantis_shrimp

Sure, the Mantis Shrimp may be beautiful, but these guys are insane. Have fun trying to sleep tonight.

I'm kidding. I will, though, leave you with this video from "True Facts". I would definitely watch this if you want to see their power punch in action (plus, the video is pretty funny).

Invasive Sea Anemones Threaten the Health of Coral Reefs Due to Sunken Ships

Healthy coral reef- Picture by Kydd Pollock

 

Iron leached out from sunken ship with surrounding invasive sea anemone- Picture by Jim Maragos, USFWS 

 

In 2008, scientists began to notice the declining health of the Palmyra Atoll coral reef in the central Pacific due to several shipwrecks in the surrounding area.  Warming seas and ocean acidification were already affecting the health of the reef, but excessive growth of Rhodactis howesii due to leached iron from sunken ships further reduced the quality of the coral reef.  Iron is an essential element for many marine organisms, but in excess, invasive species like R. howesii can thrive.

R. howesii is a type of sea anemone that is very aggressive.  When excess nutrients like iron are available with no predators to keep populations in check, the anemones thrive.  R. howesii also preys upon coral, which further degrades the health of the coral reef. 

In September 2007, USGS researcher Dr. Thierry Work, Dr. Greta Aeby from the Hawaii Institute of Marine Biology, and Dr. James Maragos from U.S. Fish and Wildlife Service studied a shipwreck from 1991 on Palmyra Atoll in the Pacific Ocean.  The researchers discovered that R. howesii was growing in high densities surrounding the ship, and densities steadily decreased with distance from the wreck.  Since the atoll is isolated, runoff from agricultural or industrial activities is unlikely, so the shipwrecks are the only logical source of excess nutrients. 

With the sea anemone growing rapidly, it causes a change in the dominant life form of the reef and is referred to as ‘phase shift’.  Even though phase shifts can have long-term negative effects, eliminating organisms like R. howesii are an impossible feat, especially over a large area.  Rapid removal of shipwrecks to prevent reefs from being overgrown by invasive species like R. howesii is crucial to reef health. 

Remediation projects are currently being implemented to evaluate the resiliency of coral reefs after shipwrecks removal. On January 29^th 2014, the Fish and Wildlife Service completed a $5.5 million conservation project to remove three wrecked ships, weighing a total of one million pounds, from protected wildlife areas in the Pacific Remote Islands National Wildlife Refuge. The shipwrecks caused miles of damage to the Palmyra Atoll and Kingman Reef.  With the reefs being home to 176 species of coral and 418 types of reef fish, protecting the damaged reef from further destruction was vital.  A team of 16 people cut and removed the wreckage from the coral reefs without causing further damage, bringing the salvage to California to be recycled. 

A representative of the remediation project stated, "We know Palmyra Atoll is resilient; it's one of the last remaining healthy coral reefs.  We've done some experiments with removal, and within three weeks we saw new species coming back to the area—mainly microscopic coral recruits.  These resilient areas can heal themselves when they get back on track."

Using Palmyra Atoll and Kingman Reef as controls, scientists can begin to understand how coral reefs heal.  It is possible that these examples can teach scientists in other parts of the world how to restore coral reef health.

Mapping by satellite pinpoints danger zones for turtles

photograph by Michael Patrick O'neill/Alamy

Many  migratory species in the ocean face a constant battle with fisherman.  However, satellite and fisheries data can help prevent some of these battles.  Some of the animals that are most affected by bycatch include seabirds, turtles, dolphins and cetaceans.  Recently, fisheries and satellites have been tracking leatherback turtles (Dermochelys coriacea) in the Atlantic Ocean and trying to prevent these unintended captures. 

The Atlantic Ocean is home to the last large populations of leatherback turtles.  Because these turtles have a migratory nature and are considered to be the world’s largest turtle, they are very vulnerable to unintended capture by fisherman.  In the past, understanding how to protect these turtles has been difficult because much of the bycatch is not reported by fisherman and the turtles cover very wide paths in the Atlantic.  The satellites have tracked leatherback turtles from 1995 to 2010 to find out many of the zones that the turtles regularly occupy, and to identify some areas where they may clash with fisherman.

A conservation scientist named Brendan Godley explained that the largest obstacle to protecting the turtles has been knowing where, when, and in what fisheries the bycatch is taking place.   He has published research that pinpoints four sites in the north Atlantic and five sites in the south Atlantic that are high-risk areas for leatherback turtles.  These high-risk sites include the economic zones shared by 12 different countries including the US and UK.  In these economic zones, many of which overlap with high-risk turtle zones,  longlines are cast regularly for tuna and other commercial fishing occurs here.

Action is being taken to protect the populations of these leatherbacks in the Atlantic, because the populations in the Pacific Ocean have nearly been wiped out and are considered critically endangered by the International Union for the Conservation of Nature.  Another scientist named Matthew Witt said that reversing the trend in the Pacific is almost impossible, but with his research they are trying to prevent this from happening in the Atlantic. 

His team was able to provide satellite data from over 100 turtles, showing their standardized tracks and also including longline-fisheries data to identify areas of low, medium and high interaction between turtles and humans.  The team then made a map that covers the Atlantic in a grid with squares that are 5 degrees latitude by 5 degrees longitude. 

Then, Rebecca Lewison, a conservation ecologist, backed up Witt’s team research by stating that his analysis makes it harder for governments to ignore the danger that bycatch poses to migratory species, including the leatherback turtles.  She also pointed out that ocean-wide scales like this one have to be taken into consideration if people are serious about preventing the extinctions of pelagic species. 

In summary, these scientists are all working together to prevent the bycatch of migratory species.  If they know where the turtles and other species are regularly found, fisherman can reduce bycatch by making better decisions on where to fish.  Maps like the one created in this study from satellite data can be used as a tool to prevent fisherman bycatch.  Longlines and other coastal fishing gear such as trawls pose the greatest risk to turtles, and future research can be done to incorporate these dangers into the maps as well. 

Resource

Related PDF

A quieting ocean: Unintended consequences of fluctuating economy.

            Climate change, conservation, energy, overpopulation, and pollution may be the most talked about environmental issues today. Public leaders have even down played some and voters saying, “it is junk science” or “it can be improved all the time.” Well, out all of the ones I have mentioned, I think it would be hard for anybody to down play pollution. What do you think of when you hear the word pollution? For me it is the Cuyahoga River. It caught on fire not once, but twice! It made Cleveland infamous though and it carries on today. It did spark a progression for change though. The Clean Water Act established better standards for our waterways. However, there is a different kind of pollution that does not get as much attention as say air or water. Do you ever think how noisy our environment is? How do you handle noise? Do you find noise disrupting at all?

            Lets delve a little deeper. What do you think about ocean noise? Have you ever thought about it? Mind you, we are terrestrial organisms, but marine organisms suffer the same implications from noise pollution as we do. In a 2012 publication, scientists looked at ocean noise and found correlations between ship noise, economic trends, and regulations on the shipping industry.

            Increased ocean noise poses a potential threat to marine animals that depend on sound for a myriad of ecological functions. This study was trying to better understand and reduce noise in marine habitats. The researchers used statistical correlations between regional commercial ships (ships that stayed close to California) and measured low-frequency sounds they emitted. They first looked at these ships when the economy sank (no pun intended) and then when regulations from the California legislator enacted new rules on the shipping industry. They were able to evaluate the trade-offs (and the economic costs) in noise pollution reduction with economic drivers to make additional efforts in reducing noise in the ocean.

            In the end, the statistical analysis the scientist did revealed small reductions in noise frequency with the changing economy and commerce regulations. Specifically, when one ship a day did not sail, one decibel was decreased in the area in in question. During the economic slump, noise levels were significantly reduced by about 40 hertz. They did not notice any significant change in noise levels when new regulations were impose. They did notice the great costs regulations impose on shipping (roughly $19 billion). The scientist point out that legislation needs to be focused on how ships are built and not on regulating how they run.

            In summary, the researchers focus on low-intensity, chronic noise, rather than high-intensity, short duration noise. Determining the ecological and organismal impact of these noises is difficult to document damages. This is due in large part to a very large habitat (the ocean) and organisms do not stay in one place for long. Physiological impacts are also a concern. However, as research on ocean noise continues, we will be better to evaluate it and find solutions that reduce them significantly to the point were oceanic impacts will be minimal (hopefully nothing).

Source: McKenna et. Al,: A quieting ocean. J. Acoust. Soc. Am. 132, September 2012.

Neat Diagram on Oceans depths