Fossil Ammocoetes!

Recently (in October) fossils of lampreys were reported in the Proceedings of the National Academy of Science (PNAS; link to article). Chang et al report the first fossil ammocoetes ever found, as well as fossil transformers and adult lampreys, all from the same beds! Below is a picture from their article of an ammocoete (A), a transfomer (B and C), and closeups of the head of an ammocoete (D and E) and a transformer (F and G).

Below is the the top panel A with one of my ammocoetes imposed over top of a fossil ammocoete and a picture of the live ammocoete below.

These fossils were found in Lower Cretaceous rocks 125 million years old, and as you can see they appear very similar to modern ammocoetes. This is important for understanding when lampreys evolved and if the ammocoete stage is useful for developmental biology studies. If the ammocoete stage evolved long after lampreys broke away from the rest of the fish ancestors it is not as useful at letting us understand how early fish lived. If on the other hand it has been around since lampreys first diverged we are literally looking back in time at an early fish.

This first ammocoete fossil lets us know the modern pattern of development in lampreys goes back quite a way. Lampreys probably diverged from other fish between 350 and 450 million years ago, but without more fossils we cannot narrow down the time more precisely. However, current evidence suggests that lampreys diverged from other fish (including ourselves) closer to the 450 million year ago mark. This makes lampreys (as a group) close to a half billion years old! For comparision dinosaurs don't appear until ~230 million years ago, meaning that they are only half as old as lampreys.

Citation
Chang, M., Wu, F., Miao, D., and Jiangyong, Z. 2014. Discovery of fossil lamprey larva from the Lower Cretaceous reveals its three-phased life cycle. PNAS 111 (43) 15486-15490.

Final Sampling Day of 2014

I have finished sampling for this season. The water is getting colder and higher, and the leaves are starting to cover all of my sampling sites. It felt good to finish up part of my work.

The face of a stream changes every day, but it is very obvious during the fall after the first rains. The water is rising and will cover this cobble bar probably for the rest of the year.

 A similar picture, but look at the differences in the greenery around the stream.

The net I use to keep my animals in my study area as I collect them. Here it is set around one of the pools I sample. The large tree behind them is a log that was trapped under the bridge when water levels were higher. It has been there all summer and may have been trapped there during the spring floods.

A picture looking at the same area, but a better view of the net and the box it gets stored in.

I had help from an undergraduate who volunteered from the course I am teaching. It drizzled during the day so he wore is hood down.

Here he is measuring a lamprey and preparing to take its weight.

Two pictures of the same handful of lampreys. The smallest animal immediately in between my fingers is <1 year old. This animal was washed downstream during the fall rains and made it here. I have no idea how far down it came, but it could be from quite a ways upstream. The other animals in the picture are probably about 1.5 years old now.

The other side of the bridge. The trees on the mountains have already dropped their leaves for the most part, and we are getting ready for winter.

Last Trip to the Genesee River this Season

This was my last trip to the Genesee River this season. I will return (as General MacArthur said) but not until the spring of next year. Water temperatures will be too low for me to get my little guys to emerge from the sediment, and the falling leaves make seeing them increasingly difficult. Also fall is generally a rainy time in the Northeast (though we have not had any yet) and water levels will start to rise very quickly once the rain does arrive. Finally, I am sure on sunlight. I finished with ~15 minutes left, and the days are only getting shorter. In very short order I will not be able to do a single site in a day. Hopefully next spring some of the animals I tagged will still be in the stream, although I suspect that many of them will have washed away down river by then.

One of my lampreys getting weighed and showing off all its tags. It was just about ready to be dropped into a bucket to recover.

The fall is certainly here. Willow leaves starting to build up. As the trees drop their leaves they release the nutrients stored in those leaves in the water. They also allow much more sunlight to get into the stream and algae growth booms this time of year. The rocks were well covered and very slippery.

The tree which those leaves probably came from further upstream. Only a month ago everything was bright green and growing well.

A tree that marks the site of one of the pools I sample. It has already lost almost all of its leaves. The pretty pink string marks my study site.

The same tree slightly further away. The "pool" I collect from here is really just the margin of the stream where some sediment has built up. Actually the animals I catch under here don't really move even though there are no barriers that would prevent them from doing so.

One of my smallest lampreys. I continue to catch this animal (and have since August) at the same pool. It has grown just 3 mm in 3 months. If you grew as slowly as it you would need millennia to get to adult size. Even for lampreys this is really slow. Other animals its same age are about twice as long and more than twice as heavy. This animal is probably not sick or having a problem, it probably just cannot get much to eat and has to grow very slowly. At the rate it is going it will be an adult in about a decade. It will probably get washed downriver this fall and if it does it may find growing conditions better in its new home. Obviously catching such a small fish over and over suggest that mortality is fairly low once they find a place to burrow.

One of the pools where I catch many of my study animals. There are quite literally hundreds of lampreys in this pool. I have not yet seen one other fish in the pool, which is also pretty cool. The pool is now coated in algae so catching them is a little challenging. It will be easier again once I return in the spring.

More plants marking the edge of another one of the areas I sample.

Many of the trees have lost their leaves already, but some are still losing them.

On the Delaware River before the Fall

Fall is rapidly approaching and while I was out sampling this weekend I definitely saw that. The water is getting colder and the trees are changing color.

The water level is also extremely low (as is normal during this time of the year). Here is a picture of where I work. When the water levels go back up this rock bar will be returned to the stream.

A picture looking upstream partially underwater of the same area. The water is so green because it was very cloudy.

The new rip rap put in by the NYSDEC to provide parking. This is not actually good management unfortunately. The rocks will turn the stream into the other bank and cause the river to erode into the bank just in front of the bridge. Likely DOT will need to come out in the future.

 

A small dam just upstream. Behind the dam is a pool where I catch lampreys every month. They do appear to leave here with some regularity so it is not a complete barrier to their movement.

Just before I left I took a picture of the valley from the parking lot. Quite a scenic place.

Tagging American Brook Lamprey

I returned to Dyke Creek last Saturday with my wife so I could finish sampling in one day. We had to wake up early and we did not return home until almost midnight, but we did manage to finish the entire site. Unfortunately, we did not capture any transformers, but since Cait was with me there are pictures of me. We stopped taking pictures relatively soon after arriving as we were trying to get through samples as quickly as possible so we would finish before the sun went down.

This picture was taken just to the right of the first pool and looking downriver. The stream actually braids into two separate channels just above this point, so this is about half of the stream.

Route 417 as it passes over the site. We set up our first sample processing station just under neath. Cait moved it slightly so she could sit in the sun.

Working up an animal with the syringes used to inject the color in the foreground.

Brought a chair this time so I (or Cait) did not have to sit on the cold rocks. Temperatures started off in the 50's and rose into the high 60's low 70's by the end of the day. Water temps held steady around 58°F.

A nice picture, taken by Cait, from the shore.

Setting up the blocking net before starting to shock to prevent lampreys from escaping while I worked.

Pictures of me sampling further upriver. The pool here had quite a bit of algae growth so my ability to catch the lampreys here (where Brooker lives) was low. That is not a problem for the models I use, but means that the total number of animals we needed to work up on this sampling occasion was not as high as in the past.

I am trying to go out again this weekend. If I succeed I will update the blog again. Until next time, happy lamprey hunting.

Maine and the Delaware

Sorry for the long delay, but I was in the field almost continuously since Thursday. I visited my sites in the Delaware River before I headed all the way to Maine to do work with another researcher. Of course pictures were taken and lampreys were captured.

Lamprey having its weight taken after the length was measured.

 A bunch more lampreys and at the bottom a transformer. He was tagged but interestingly his body destroyed the tag. The scars are still present from where the tags were, but the colors are completely gone!

 I had help so there are even some pictures of me, here posed.

 Working up some lamprey on a gravel bar in the stream.

 Showing off one of the trophy ammocoetes while recording data and preparing to tag.

Last picture of me standing ready to go hunt for some lampreys with water for myself. When temperatures break 80F I can easily go through a gallon of water in a day, since I may have to stand still in the sun for 1-2 hours while collecting the ammocoetes. It's a good idea to know your biting flies so you can quickly decide if you need to kill or ignore the animal that just landed on your arm or face.


And now pictures from Maine. Last time I went I did not have a functioning camera. This time I had a camera (courtesy of my considerate in-laws) so I made sure to take lots of pictures.

Picture of one of the streams I worked at in Maine. This is a shallow stream (as you can see) but in the spring 100's of adults swim through here looking for a good place to make nest for their eggs.

And here are the nests of two lamprey pairs now 2 months after they were created. When the water was up the entire nests would have been covered. Now that the water has come down the very lower portion of the nests are exposed. The eggs have already hatched and the tiny ammocoetes (~8 mm long) have moved downstream to find a place to call their own for a few years.

Two pictures of areas where ammocoetes collect. In the top picture we found more than 40 animals, and in the bottom pool we only shocked a section but collected about 50 animals.

Here are some of the lampreys immediately after capture. Note that they are very small, the animals we found in Maine are frequently half the size of their compatriots in the Delaware River. This is not because of genetic differences between populations (lampreys do not return to a natal river, they only return to a river they consider suitable to spawn in), but is instead related to the length of the growing season. Numerous short growing seasons keep the animals small and encourage them to give up growing as soon as possible and try to make their living at sea on other animals. Look out for the very small animal towards the center, that animal is probably 2-3 months old and is the largest that animals from this year are at this time.

An underwater video of some of the fish that share the same habitat. See if you can spot some of the fish that Maine lists as "baitfish" here (link).

Genesee River

Sorry for the long time between posts. My older camera (which I got for free when I purchased my computer to enter college) got some grit in the camera motor and cannot extend the lens any longer. As a result it could not talk any pictures so I was hesitant to fill the blog with text about my work. As an early birthday present I received a more rugged Fuji camera, so today will be filled with images as well as some underwater footage! Please note I was working alone so these pictures/videos will not be great as I was trying to do two things at once and the sky was overcast so the light levels were pretty low.

 The above pic is a good size distribution of the ammocoetes I see at my site. Keep in mind these are American brook lamprey so ammocoetes can be quite large (approaching 25cm). The animal at the top is likely a two year old (sorry I captured no animals <2 years old at this pool). Bottom bar is in cm's, top two bars are in inches.

It must be August because some ammocoetes are already getting ready for spawning in the spring. The animal below is a "transformer". You can see the eye developing the head shape is changing and the body is very thick (from all the fat reserves). The animal above is a normal ammocoete. The lower animal will probably feed very little in the next 8 months and will travel upstream to spawn in March or April (whenever water temperatures are good for spawning). Here it is showing off the tag it received before it was released.

 Another similar picture of the same animals, with a little different lighting.

Don't let anyone ever tell you lampreys are not important for ecosystems. I captured all of these animals in an area of about 1m² of habitat.There were actually quite a few more this is just part of the first pass. The amount of biomass literally under your feet as you walk through a stream can be quite surprising! These are the fish in the sand, but think of all the invertebrates (insects, worms [of all kinds], leeches, etc.) that are also in these areas. Animals like these bioturbate, convert plant and detritus into animal biomass, and actually change the very chemistry of the world they live in.

Above is a picture of the electro shocker I currently use. Backpacks like these use a small battery and control the output to surprise and stun fish. The Smith-Root LR-24 allows me to use a low power shock to scare the lampreys out of the substrate. Once they emerge I switch to another high power setting to immobilize them briefly so I can collect them. The yellow paddle is the stock paddle provided by the company. The white paddle is unique to lamprey hunting and is a modification of the other end (normally a long bare metal wire) so I can shock and grab by myself. The battery in this picture is under the control pannel on the back and is covered by a plastic piece. The battery is unfortunately for me, Lead-Acetate, and weighs ~30 pounds. Having 30 pounds on your back is not that big a deal, but it sits low and it is much harder to walk in the slippery streams when your center of gravity is shifted back and behind you.

This is one of the coolest pictures I took while I was out. There is some debate about whether and how much ammocoetes get eaten. Well here is proof that even large ammocoetes are the target of predators. This animal apparently was lucky because all it did was lose almost all of its tail. Here the tail is slowly growing back, although that probably limits its ability to swim until it does.

A close up of the tail from the injured animal. I promise I had nothing to do with this. The animal was not even one of the one's I had tagged until yesterday.

Another recap from May 2014 quietly sitting in the same sheltered pool it was left in last time. Hopefully it remains so I can keep catching it and seeing how fast it is growing. At the rate it is going now it will be an adult in 2016 or maybe 2017.

Above is a video of some of the lampreys being placed under general anesthesia before I begin tagging them. The anesthesia is irritating to mucus membranes (which is basically the whole lamprey body) so they are swimming around trying to find a way out. After about 60 seconds things settle down and the animals go completely under after 3-4 minutes. By the time they wake up they have been tagged, weighed, and had their length measured.

Here is a video of me releasing my tagged lampreys into the pool in which they came from in the first place. The animals are very excited to get back into the sediment. You may notice a net on the edge of the pool. I use a net to keep animals from escaping as I capture other by surrounding the area I am working with a net. I leave it there until all the animals re-burrow.