Now this is a pill bug...

Isopods of the genus Saduria are common nearshore animals in Arctic shores of Alaska.  Saduria entomon gets pretty big, this one is over 2 inches long.  We have a couple of species in Alaska including S. entomon and S. sibirica.

Sadurid isopopds are canivores and scavengers feeding opportunistically on anything they can find.

Here is a photo of the head. These are amazingly adaptive and resilient animals.  They survive in freezing conditions, low oxygen, little food, and in a wide range of habitats from gravel to mud.  Once, a student assistant was sorting a poorly preserved benthic sample and after ~6 months of preservation, he found a small Saduria swimming in the jar.  No other organisms were present indicating it ate everything else in the sample!   Talk about tough, it was surviving in a weak formalin solution, there would have been little oxygen, eventually, no food, and the animals it ate contained formalin as well.  I vote for these as being the tough guys of the Arctic.

Would you be afraid of this Alaskan predator?

The scaleworm Gattyana cirrhosa.


Scale worms are predatory marine worms common throughout Alaska's marine waters.  Their feeding habits are described for a few species that feed on smaller organisms, and it is presumed the others feed similarly.  Note the eye spots near the head and the bushy setae.  

The scaleworms are identified by the elytra (scales) that cover their backs.  The elytra often have distinct color patterns or growths (tubercules) on them, such as those shown here for G. cirrhosa.  The "horns" in this case grow along the edge of the scale.

The setae are characteristic to each species with this animal having very bushy setae throughout.

Scaleworms occur regularly in soft sediments throughout Alaska, presumably in association with their prey.  They are highly mobile and can get quite big, depending on the species. 

This particular animal was recently found in the Chukchi Sea.  It was about an inch in length total and was missing many scales and other parts due to  handling. 

A snow day and climate change

Today is a "Snow Day" with school canceled due to bad weather. We are all in a positive mood due to the change and unexpected "holiday".  I was reminded that I haven't blogged for a long time and today is a great day to get back on track!

Thinking of freezing rain and poor conditions, negative effects from "climate change" are thought to be greatest and fastest in the polar regions.   (I prefer the term "climate variability" rather than climate change to reflect the uncertainty about the multiple causes in long-term trends and emphasize the variation, not the change itself.)  Summer ice cover in the Chukchi Sea has been consistently very low, marine mammal distributions have changed, and it is reasonable to ask how systems have changed during the period of greatest change in the Arctic?   My recent publications can shed some light on this topic although, unfortunately, the data do not exist to make real inferences (repeated sampling over time of the same locations in representative areas). First, I want to present what we know from Port Valdez, a glacial fjord that does have an appropriate database for demonstrating temporal change.  The Pacific Decadal Oscillation (PDO: http://jisao.washington.edu/pdo/) is the temporal variation of oceanographic conditions in the North Pacific Ocean and the characteristics summarized in the PDO have large ecosystem effects. Among related patterns, the higher water temperatures associated with positive PDO values are related to greater precipitation along the coastline.  A relationship can therefore be expected between benthic fauna and the PDO, as the following plot demonstrates:

The relationship above may occur through increased availability of food through greater inputs of organic carbon, greater survival and recruitment of juveniles, or other pathways.  Curiously, biomass has a negative association with PDO suggesting that the higher abundance is due to greater influxes of juveniles, and not the success of older animals. I need to dig much deeper into this issue.

Can a similar pattern be observed in the Chukchi Sea?  Based on 5-years of data, significant variations in faunal abundance (density) do reflect some oceanographic conditions, although no single variable serves as a primary covariate.  Here is a plot of abundance from our Chukchi Sea study 2008 - 2012 demonstrating significant temporal variability, although the variables driving that are not understood.

It appears that the older animals survive from year-to-year (biomass remains fairly constant) but abundance and the number of different taxa found in each study area vary significantly. Find our reports and other information at http://www.chukchiscience.com/.

Compare the trends marked in blue in the above plot with this plot of the Arctic Oscillation, a climate index for the Arctic:

Not too much relationship between the last two plots.  There really isn't enough data for inferences, but it doesn't look at first glance, like there is a relationship in the Chukchi Sea, like that in Port Valdez. This also needs further attention.

Corals in the Chukchi Sea, Alaska: the Sea Raspberry

The sea raspberry

Recent interest has highlighted the occurrence and distribution of soft corals in Alaskan coastal waters.  I thought posting some ecological information on this species may be useful.


The sea raspberry, Gersemia (Eunephthya) rubiformis (Ehrenberg, 1834), is one of a number of anthozoans (sea anenomes, corals, sea pens and sea whips; phylum Cnidaria) found in Alaska waters.  These animals are predators, feeding on small plankton that they may capture while suspension feeding. Unlike the stony and reef-building corals so many people are familiar with, soft corals do not build a hard, calcium carbonate skeleton.  Soft coral have a soft, leathery surface and build irregular, often branched colonies.  Sea raspberries are generally small colonies and their color ranges from light pink to red. Sea raspberries in Alaska are actually two known species: Gersemia rubiformis and Gersemia fruticosa.


The sea raspberry has long been known to inhabit US Arctic waters and is found throughout the Bering and Chukchi Seas and has been noted in publications as recent as 2009 (MacGinitie, 1955; Sparks and Pereyra, 1966; Feder et al., 2005; Bluhm et al., 2009; RACE database: http://www.afsc.noaa.gov/RACE/groundfish/survey_data).  The sea raspberry is a circumboreal species found throughout cold waters of the northern hemisphere and noted along the northeastern Pacific coastline from California to the Chukchi Sea. We find it to be broadly distributed in the Chukchi but generally, colonies occur in low densities overall offshore. 


Epifaunal organisms (animals living on the sediment surface) have a range of life habits from sessile suspension-feeding animals such as sea squirts (ascidiaceans) to highly mobile predators such as crabs.  Epifaunal communities include a number of animals that build colonies extending into the water column and thus, creating microhabitat.  These include sponges, sea squirts, bryozoans, and many others.  Colonial epifauna may require hard substrates for settlement and growth but some can establish themselves in soft sediments. 


In the northeastern Chukchi Sea, hard substrates are less common offshore so the colonial organisms requiring such habitat are less common. As a colonial epifaunal species , the sea raspberry attaches to hard surfaces such as rocks and the shells of large animals. Thus, although regularly captured during sampling and ubiquitous across the Bering and Chukchi seas, the sea raspberry is habitat limited offshore. Corals are usually associated with rich ecosystems with many animals dependent on the corals for food and protection.  Being small colonies in the Chukchi (usually on the order of 10 to 20 cm), these organisms wouldn't provide the microhabitat for other species often provided by large corals and dense epifaunal assemblages.

Epifauna on snail shell

 Talk about recycling, the snail shell to the left is occupied by a hermit crab and has a chiton, some barnacles, a sea raspberry, and other colonial epifauna attached.


See also the webpage at http://www.afsc.noaa.gov/groundfish/HAPC/SeaRaspberry_synopsis.htm for more information.

References:

Barnes, R.D. 1987. Invertebrate Zoology, Fifth ed. Suanders College Publishing, Philadelphia.  
 

Bluhm, B.A., Iken, K., Mincks Hardy, S., Sirenko, B. I., and Holladay, B. A., 2009. Community structure of the epibenthic megafauna in the Chukchi Sea. Aquatic Biology 7, 269-293.

Feder, H.M., Jewett, S.C., Blanchard, A. 2005. Southeastern Chukchi Sea (Alaska) epibenthos. Polar Biology, 28:402-421.

Kesseler, D. W., 1985. Alaska's Saltwater Fishes and Other Sea Life. Alaska Northwest Publishing Co., Anchorage, AK.

MacGinitie, G.E. 1955. Distribution and ecology of the invertebrates of Point Barrow, Alaska. Smithsonian Misc Collection 128:1-201.

Sparks, A.W., Pereyra, W. T. 1966. Benthic Invetebrates of the Southeastern Chukchi Sea. In Wilimovsky, N. J., Wilfe, J. N (eds). Environment of Cape Thompson Region, Alaska. United States Atomic Energy Commission.

Ushakov, P. V., 1955. Atlas of the Invertebrates of the Far Eastern Seas of the USSR.  Israel Program from Scientific Translations, 1966

Macrofauna and hydrocarbons in the marine enviroment

In my work in Port Valdez, Alaska, we sample around the marine oil terminal in Valdez to determine the biological and chemical characteristics in support of the NPDES permit for discharges of treated water from the oil terminal.  Some sites have been sampled since 1989 and some since 1971.   Our work serves as a indicator for potential changes in the sediment environment that could signal a disturbance event.
Responses of macrofauna (animals living within the sediments) to hydrocarbons in the marine environment are varied and can be difficult to identify.  Animals living in sediments can persist in the presence of fairly high hydrocarbon concentrations after oil spills.  Dauvin (1982) found that while adults persisted, some young invertebrates didn't appear to recruit to contaminated sediments.  Crustaceans such as amphipods are particularly sensitive to hydrocarbons and marine worms can be harmed as well. Others, the opportunists (largely tolerant polychaetes) increase in abundance so following changes in abundance of the macrofauna is a very suitable tool for measuring effects from disturbance.

Sediment quality criteria are a means to evaluate the risk of effects on biota by considering a single value.  It is desirable to use one value as an index of risk for effects on fauna.  A popular choice is the Effects-Range Low (ERL).  For aromatic hydrocarbons (the part that animals are most sensitive to) the ERL value is about 4,ooo ng per gram.  A question lingers though, at what levels do animals really respond?

Our research in Port Valdez has found animals responding to sediment hydrocarbon values between 100 to 300 ng per gram, much less than the ERL.  The figure below is a space-time model of the changes in hydrocarbons in sediments (PAH) and the abundance of two worms.  The vertical (Y) axis in each plot is distance along a transect that crosses the point of discharge at the marine oil terminal in Valdez.  The horizontal (X) axis is time.  The first plot shows the areas of highest risk (red) for effects from PAH.  PAH concentrations have declined over time due to improvements in the ballast water treatment plat in Valdez.  My interpretation of the other plots is that as PAH concentrations declined to around 100 ng per gram, the abundance of the two sensitive worms increased as juveniles began to recruit in.  

 

A conclusion from this work is that researchers in our field may be understating the effects of hydrocarbons in the marine environment.  Effects are occurring at levels lower than the commonly used ER-L criterion and that values is becoming widely used.  Thus, we should be careful in drawing conclusions of no effect from hydrocarbons in the marine environment when concentrations are slightly elevated.  

References:

Blanchard, A. L., H. M. Feder and D.G. Shaw. In press. Associations between macrofauna and sediment hydrocarbons from treated ballast water effluent at a marine oil terminal in Port Valdez, Alaska. Environmental Monitoring and Assessment.

Dauvin, J. C. (1982). Impact of Amoco Cadiz oil spill on the muddy fine sand Abra alba and Melinna palmata community from the Bay of Morliax. Estuarine, Coastal and Shelf Science, 14, 517-531.

Climate variability in glacial fjords

A poster summarizing our long-term study in Port Valdez was presented at the Western Society of Naturalists in San Diego.  The data presented were the abundance and biomass of fauna found in the sediments of the deep basin of Port Valdez.  Port Valdez has two sills (underwater terminal moraines at the mouth of the fjord) and a deep basin (> 240 m). The general shape of the basin of the fjord is like a bathtub resulting in limited exchange of the deep water with surface layers. Thus, the fauna of the deep basin are thought to be less affected by short-term fluctuations at the surface and more responsive to annual cycles.

I found two trends in the database representing large-scale variations.  The first was a response to the Great Alaska Earthquake in 1964 and the second was an association with the Pacific Decadal Oscillation (PDO). The PDO is a measure of sea surface temperatures in the North Pacific Ocean and has been shown to be associated with large-scale variations in biological characteristics of the North Pacific including survival and recruitment of fish stocks. Glacial fjords may be particulary sensitive to climatic variability through variations in the melting rates of glaciers.  Warmer oceans = more rain and higher temps = faster melting = increased runoff flow into fjords.

 Although the deep basins of fjords are somewhat isolated from short-term changes in surface waters, many invertebrate larvae spend some time in surface waters so the deep subtidal fauna community composition will be influenced by environmental change through larval recruitment.  For example, field studies have shown that survival of bivalve larvae is influenced by water temperature.  Thus, the pathway exists for long-term climatic variability to influence benthic communities through pathways other than food web variations. 

In my work, I found a positive association with the overall abundance of infaunal animals in the deep basin of Port Valdez, Alaska.  This plot shows the trends in average abundance of stations in the deep basin and the average PDO index value for each year.  The tight association between the two values after 1987 is remarkable.  The lack of trend prior to 1987 is also interesting and appears to be related to a recovery process from the 1964 earthquake (a topic to follow).

 I haven't yet had the chance to explore the data to understand how the communities respond to the PDO but the data indicate a pretty strong relationship.  Our next step is to mine the data to find animals whose abundances are positively and negatively associated with the trends in the PDO.

Marine biology in Fairbanks, Alaska

What could be better than being a marine biologist? You get to travel to out of the way places, work with cool animals, and do things few other people get to see or do.  Projects in my lab right include a study in the Chukchi Sea, the Beaufort Sea, and Port Valdez, Alaska. 

I'm an invertebrate taxonomist, benthic ecologist, and statistician.  Most of the work we do in our lab is identifying invertebrates from sediment samples, mostly worms and clams.  It may sound boring, and at times it is, but we get to see some really cool stuff!  Check out the photo below of the polychaete worm Pista cristata taken with our digital microscope:

Pista cristata

I manage a long-term project in Port Valdez, Alaska, that has completed it's 40th year of sampling.  In science, 3-5 years is often as much as people get to work on one project so 40 years is a LONG time to work in one place. 

Priapulus caudatus

Port Valdez is a glacial fjord in Alaska surrounded by the Chugach mountains.  On a clear day, I'm not sure that there is any prettier place in Alaska than Port Valdez.  The Port Valdez Environmental Studies project monitors sediments to support the NPDES permit for discharges of treated ballast water.  I've been evaluating the long-term data set for indicators of long-term change and have demonstrated responses of fauna to the Great Alaskan earthquake in 1964, climatic variability, and human activities in the fjord.  You can check out my website (see the links on the blog) for more information and publications on my projects.

Our project in the Chukchi Sea is to establish baseline environmental conditions in the NE Chukchi Sea.  My team has had a great time sampling and working in the Arctic.  Among other things, we are looking towards drawing some comparisons to data from earlier studies in the 1970's and 1986 to see if there have been any changes in the fauna over time.  

Until the next post, remember: invertebrates rule!