ISIIS in the field: OSTRICH cruise in progress

Hi Plankton Portal!

The Science Team is currently out in the field in the Straits of Florida, on the R/V Walton Smith, sampling with both ISIIS and MOCNESS (Multiple Opening Closing Net and Environmental Sampling System), on an 18-day cruise titled OSTRICH (Observations on Subtropical TRophodynamics of ICHthyoplankton).

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The overall goal of this NSF-sponsored project is to quantify the patterns and consequences of the fine-scale to sub-mesoscale distributions of larval fishes, their prey, and their predators near and across a major western boundary current passing through the Straits of Florida. By sampling a series of water masses at very high resolution, this study addresses specific hypotheses concerning: i) the drivers of aggregations and patchiness, and ii) the biological consequences of predator-prey interactions at fine scales.

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Sample ISIIS images showing diversity of plankton from multiple coastal sites (including the Southern California Bight!)

Sampling involves a novel combination of detailed in situ sampling of the horizontal and vertical distributions of plankton, targeted fine-scale net sampling, and analyses of individual-level recent daily larval growth to enable the identification of the biological and physical processes driving fine-scale plankton distributions.

Follow along on the ISIIS facebook page as we periodically post updates (via our terrible internet connection at sea!) and also check out this cool video made by one of our cruise participants, Chris Muiña:

 

 

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Pteropods By Dorothy Tang

Pteropods are a group of organisms that we’re not focusing on because they are not very abundant in the Plankton Portal dataset. Nevertheless, you may have run across a few of those fascinating little creatures.

Pteropod, which means ‘wing-foot’ in Greek, is a group of free-swimming pelagic gastropods (snails). Officially, the word ‘pteropod’ is no longer used in taxonomy; it is a collective term which refers to two clades of gastropods—thecosome (shelled body) and gymnosome (naked body). Pteropods are quite unique because in order to adapt to life in the water column, their foot is modified into two wing-like flippers used for swimming. Their body size ranges from a few millimeters to several centimeters – so they’re easily imaged by ISIIS. They can be quite abundant in certain regions of the world’s oceans, and are typically found near surface waters.

The first group of pteropods, thecosomes, are also known as the sea butterflies. They have a pair of large ‘wings’ and swims by continually flapping them. Their body is encased in a delicate and translucent shell.The shell can be coiled, needle-like, triangular, and globed.

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Thecosomes are omnivores. Their diet consists of diatoms, dinoflagellates, and zooplanktons such as copepods, tintinnids, and other gastropod larvae. They capture food by secreting a spherical mucus web several times larger than their body. Scientists believe that the use of the large size mucus web is to capture large, fast swimming prey, such as copepods. The web acts as a filter: particles that are too large for ingestion are removed. During feeding, the mucus web is suspended above the animal while the animal remains motionless below. Ciliary action draws back the web to the mouth and the whole web is ingested.

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Thecosome reproductive biology is quite unusual. The animal first matures and functions as male. The male pteropod mates with another male and the sperm is stored until the animal changes into a female. When the animal turns into female; its male reproductive organs degenerate. The female lays fertilized floating egg mass that later hatch into swimming larvae (veliger).

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When a thecosome dies, its shell sinks to the bottom of the sea and forms sediment called pteropod ooze. The shell is composed of aragonite, an unstable form of carbonate mineral. Anthropogenic ocean acidification is one of the challenges that pteropods face. The increase of anthropogenic carbon dioxide level in the atmosphere reduces pH and carbonate ion concentration in the ocean, thus decreasing the calcium carbonate saturation level. As a result, the production of biogenic carbonate becomes more difficult. Overall, they have a hard time secreting their protective shell because of ocean acidification.

The second group of pteropods, or gymnosomes, are more commonly known as sea angels. They have much smaller wings which appear as side lobes. They are more robust and lack a shell. Unlike their thecosome relatives, gymnosomes are carnivores. They are active hunters and exclusively prey on thecosome pteropods. A combination of hooks and a toothed radula are employed to extract the flesh from the thecosomes’ shells.

The reproductive anatomy of gymnosome pteropods is similar to thecosomes pteropods. The only difference: the male reproductive organs do not degenerate in females. Gymnosomes has two distinct larvae forms. Eggs are hatched into shelled veliger. The veliger metamorphoses into a shell-less polytrochous larvae. The polytrochous larvae are initially wingless and movement is achieve by three ciliary bands. They gradually grow wings and lose the ciliary bands as they become adults.

Here is a very nice video about Pteropods.

Plankton Chronicles Project by Christian Sardet, CNRS / Noe Sardet and Sharif Mirshak, Parafilms. See Plankton Chronicles interactive site: planktonchronicles.org

Why do we need Citizen Science?

In many fields of science, new technology is leading to unprecedented data production. This, in turn, requires extensive analysis with minimal sub-sampling to detect as much detail as possible. In biological oceanography, imaging systems have become more useful with increasing computer speed and storage capabilities, and image data address some of the fundamental problems with traditional sampling methods that are destructive to fragile organisms (i.e., jellyfish and marine snow). On a given tow with our system, the In Situ Ichthyoplankton Imaging System (ISIIS), we produce approximately 400,000 images in 7 hours with many different species across a range of sizes present in each image (500 μm to 13 cm). This is an incredible amount of information that would take years for one person to fully analyze. When we are out at sea, we typically sample for WEEKS and come back to land with millions of images. Computer algorithms can perform basic tasks of extracting specimens that look similar, but human brains are extremely adept at interpreting an organism in 3D and providing context in the image data that a computer cannot. The amazing abilities of people to recognize patterns that computer algorithms may see as unimportant cannot be underestimated.

Shrimp photograph taken from under a microscope

Shrimp photograph taken from under a microscope (photo credit: Cedric Guigand)

Another reason we are using Citizen Science is so that you, the citizen scientist, can participate in the process of discovery. After all, most oceanographic research is funded at least in part by taxpayer money, and these novel plankton images combined with Citizen Science are a great way to engage those who fund the research. We think it is far more effective to cultivate interest in science through the discovery process itself, rather than the production of jargon-filled reports and papers only understood by other oceanographers (don’t worry, those will come later). In addition, this online format provides an opportunity for us to educate people about life in the oceans, potentially inspiring the next generation of ocean scientists. With Citizen Science, there is the potential for new discoveries arising from simply allowing many people to look at the images.

This larva of a deep water shrimp was captured in the Gulf Stream near South Florida (Photo credit: Cedric Guigand)

This larva of a deep water shrimp was captured in the Gulf Stream near South Florida (photo credit: Cedric Guigand)

We believe our research with ISIIS is particularly applicable to Citizen Science and the process of discovery because this new imaging technology provides a huge amount of data and a unique glimpse into ocean life. I have spent the last 5 years of my graduate school career at the University of Miami examining hundreds of thousands of plankton images, and every time I flip through the images, I always have the feeling that I could see something that no human has ever seen before. I try to instill this sense of wonder and hope for discovery in all people that work with the images, because when you see something interesting, like an elaborate siphonophore or a dense patch of copepods, you are likely the first person to see that species in its natural environment. When we get enough eyes on these images and discussions facilitated through the Plankton Portal website, the sky’s the limit for the discoveries that can be made with Citizen Science!

Why use images to study plankton?

Although ocean science has made many great advances, many biological processes are still poorly understood. In the sciences generally, a common theme is using new technology to examine patterns on smaller, more fundamental scales (e.g., DNA technology in biology, nanoparticle physics), with the goal of revealing underlying mechanisms. Plankton imaging is a method to examine patterns of organisms on a smaller scale, giving insight into how these organisms live and interact with each other. In addition, many planktonic animals are fragile and easily destroyed by plankton nets: the traditional tool to study plankton distributions. These plankton nets also suffer from the problem of having to sample over large portions of the water column, so an oceanographer might use a single net to capture copepods and shrimps and assume that these organisms co-occur if they appear in the same sample. However, it is entirely possible that the organisms are confined to discrete thin layers that do not overlap spatially. An imaging system can distinguish between these two scenarios, while a plankton net cannot. Images also provide information about the natural orientation of plankton, which can allow us to make predictions about their movement and feeding strategies.

 The bongo net is a traditional tool of biological oceanographers but is biased toward plankton with a hard exoskeleton (crustaceans) (Image source: NOAA Cruise DE 10-09 Report).

The bongo net is a traditional tool of biological oceanographers but is biased toward plankton with a hard exoskeleton (crustaceans) (Image source: NOAA Cruise DE 10-09 Report).

When we think about the future of our planet, climate change and predicting its effects are of great concern. In order to make meaningful predictions about a system, you need to create a mathematical model. One of the most important aspects of any model is the initial conditions and baseline variability. For many planktonic animals, especially jellyfish, we do not know their abundance, variation, or how they interact within the oceanic food web, which is all crucial information for predicting the future of our oceans under climate change conditions. Using an imaging system like ISIIS can lead to better population estimates of many different plankton types, and this information can complement many types of oceanographic studies. Fine-scale data can improve estimates of feeding and encounter rates for planktonic organisms, which is critical to our understanding of the oceanic food web.

A colony of salps such as this one would be destroyed or broken up into individuals if sampled with a net system. The in situ image in this situation gives information on the asexual budding of this fast reproducing phytoplankton grazer.

A colony of salps such as this one would be destroyed or broken up into individuals if sampled with a net system. The in situ image in this situation gives information on the asexual budding of this fast reproducing phytoplankton grazer.

When compared to plankton samples preserved in ethanol or formalin, image data provide distinct advantages in data processing and collaboration. For one, oceanographers can tackle age old questions like what are the biological and physical drivers of plankton aggregations and dispersal, and how do plankton aggregations impact the populations of wild fish, a multi-billion dollar global industry? The ‘digitization’ of biological data improves the ability to share data, fostering collaboration among ocean scientists with differing expertise. Having these images available on the internet (through a database server) increases the accessibility of biological oceanography to students, teachers, and the public. It is our hope to one day have these images available to the public, so everyone can gain an appreciation for the diversity of life in the ocean and perhaps use them to supplement science classes. The Zooniverse and Citizen Science is a great start to achieving these goals of making ocean science more “open access,” and we are so appreciative of your help!