Monday, July 30, 2012

The 1956 Biological Reconnaissance of Middleton Island. Part 1: Marine Shells of Middleton Island, Alaska.

As mentioned in the previous blog entry, Middleton Island got the attention of science at a relatively early point in time. Due to its unique location and well preserved geological features, over the years the island attracted the attention of many geological researchers. Middleton Island, located near the margin of the continental shelf in the northern Gulf of Alaska, has emerged from the sea during several major episodes of co-seismic uplift of about 7 m, 8 m, 6 m, 9 m and 7.5 m, which are recorded by marine terraces. These uplifts have been dated at roughly 4,300, 3,800, 3,100, 2,390 and 1,350 radiocarbon years before present, respectively. The most recent uplift took place during the 1964 Alaska Earthquake, when on March 27 the whole island got lifted up another 3.5 m on average (Plafker & Rubin 1978).

In contrast with the geological interest the island has received during previous decades, the number of biological studies conducted on Middleton that have a clear relationship with the island is relatively small. Thus far the most important moment in the recorded natural history of Middleton took place in June 1956, when a field party consisting of Dr. Norman J. Wilimovsky (U.S. Fish and Wildlife Service), Dr. John H. Thomas (Stanford University) and Robert Rausch (Arctic Health Research Center, Public Health Service) undertook a biological reconnaissance of Middleton Island. Their visit had been arranged because of military activities on the island (at that time there was a large scale Cold War radar station under construction) were likely going to cause imminent disruption of the island’s natural relationships. This made it desirable to record as much as possible of the island’s natural history before the opportunity was lost. Their work was supported mainly by the Office of Naval Research and the United States Air Force, but additional support was provided by the Arctic Research Laboratory, Stanford University and the Arctic Health Research Center. These studies were aided by a contract between the Office of Naval Research, Department of the Navy, and the Arctic Institute of North America (Rausch 1958).
As far as I could see the 1956 biological reconnaissance resulted in three publications. Robert Rausch described the island’s avifauna in “The Condor” in 1958 and John Thomas published his story about the island’s vegetation in “Contributions of the Dudley Herbarium” in 1957. During their stay in 1956, the party also assembled a small collection of mollusks from the intertidal area, which had been submitted to the California Academy of Sciences for identification. Eventually G. Dallas Hanna and Leo George Hertlein identified the marine shells and these were listed and described in 1959 in “The Nautilus, The Pilsbry quarterly devoted to the interests of conchologists marine shells”.  

During my first stay on Middleton Island in 2005, however, I noticed that during recent decades little had been published about the general wildlife of the island and that the available works about the vegetation and avifauna (Thomas 1957; Rausch 1958) were largely outdated, especially due to some severe (a-)biotic changes that occurred during the decades following these publications. For me this was a good reason to start several studies on Middleton Island’s wildlife, focusing on the development of both vegetation and avifauna, in particular breeding birds. These studies started a year later and are keeping me pretty occupied up to the present day.
With this blog entry, the first of a series of three, I want to focus on the results of the 1956 biological reconnaissance of Middleton Island and share with you some of my thoughts on these and maybe present some preliminary results of my own studies in relation to these.
This first entry, however, is about a subject I know very little about and I can’t write much about either: the marine shells of Middleton Island. Now it already took me a considerable amount of time and effort some years ago finding a copy of Thomas’ 1957 vegetation study, I never managed to find a complete copy of Dallas Hanna’s and Hertlein’s work on the identified marine shells of Middleton Island. Until yesterday that is! The good news is that the whole edition of The Nautilus is now freely available online:

Dallas Hanna and Hertlein write about the collected material: “Twenty-one species are present in the lot and also one barnacle. To these may be added for reference purposes, two additional species cited by Dall (1921, pp. 32, 107) from Middleton Island. Thus the known marine mollusks from this island consist of 5 pelecypods, 14 gastropods, 3 chitons, 1 cephalopod and one barnacle. All, with one possible exception, are known to occur in waters of this general region at the present time. However, this one, Littorina arctica, may have been cited in Alaskan literature under a different name.” (Dallas Hanna and Hertlein 1959)

Now does this mean that the subject has been studied enough by now? Certainly not! Dallas Hanna and Hertlein already give two reasons why further study of the molluscan fauna could be very interesting:

“A geological investigation of the islands has been made by Don. J. Miller (1953), of the U. S. Geological Survey. During the course of his work he obtained 20 species of mollusks (identified by F. Stearns MacNeil) from Pleistocene sedimentary beds. Oddly enough, none of these species was found in the collection being considered here. It is practically certain that the lists of both fossil and recent species represent only a small portion of the total molluscan fauna of the island and adjacent waters.” (Dallas Hanna and Hertlein 1959)

Now I can come up with several more reasons to show some interest in the intertidal life around Middleton Island:

-  After the 1956 biological reconnaissance the 1964 Earthquake lifted up the whole island about 3.5 m on average, creating a new and more extensive intertidal zone around the island. This meant that the area that had initially been inspected by the 1956 field party currently makes up a permanent part of the island and does not contain live marine mollusks anymore. How did the new intertidal zone develop?

Intertidal area at the island's south end in 1960 (photo: Armand Biron)

Intertidal area in the upper east part of the island in 2005. No clear intertidal zone 
could be identified here before the 1964 Earthquake (photo: T. van Nus).

- The island remains under constant influence of seismic activity in the area, resulting in a small but continuing uplift or tilt (Prescott, W.H. and Lisowski, M. 1977; personal observations). It would be interesting to find out how over time this uplift affects the occurrence of mollusk species in the area

- Personal observations of the current intertidal zone indicate that this area can make up about half of the total size of the island itself (which is about 2 x 7.5 km). The new intertidal zone has become a majorly important foraging area for both breeding birds as well as a large number of spring and fall migrants, in particular shore birds. Very little is known what these birds find there and whether the availability of food is a limiting factor for them.

- Personal observations also suggest that intertidal life can be diverse but there are large annual changes occurring; in example the growth of kelp sp. varies a lot among years. Sea Otters (Enhydra lutris) established themselves for the first time in recorded history in the winter of 2008/2009 (van Nus, personal records). What is going on here?

Sea Urchins were very common during my first visits to Middleton in 2005 but were not 
seen often during later visits. At the same time growth of Kelp appeared to increase 
(photo: T. van Nus).

Now I never managed to find enough time to put effort into a study of the intertidal life around Middleton Island and I believe the challenge is still there, but it better needs to be done soon before another opportunity is lost..!


Miller, D. J. 1953. Late cenozoic marine glacial sediments and marine terraces of Middleton Island, Alaska Journal of Geology, 61:17-40.

Plafker, George, and Rubin, Meyer, 1978, Uplift history and earthquake recurrence as deduced from marine terraces on Middleton Island, Alaska, in Proceedings of Conference VI, Methodology for identifying seismic gaps and soon-to-break gaps: U.S. Geological Survey Open-File Report 78-943, p. 687-721.

Prescott, W.H. and Lisowski, M. 1977. Deformation at Middleton Island, Alaska, during the decade after the Alaska earthquake of 1964 Bulletin of the Seismological Society of America June 1977 67:579-586

Rausch R. 1958. The occurrence and distribution of birds on Middleton Island, Alaska. The Condor 60: 227-241.

Shepard Oldroyd, I. 1924 – 1927. The Marine Shells of the West Coast of North America.
Four Volumes. Stanford, California. Stanford University. 1520 pp. illus. ISBN: 9780804709873

Thomas, J. H. 1957. The vascular flora of Middleton Island, Alaska. Contrib. Dudley Herbarium, 5:39-56.

 Scattered boulders along the western shoreline (T. van Nus).

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