Research Overview

Although trees are the archetypal example, a wide range of organisms form annual growth increments. The list includes fish, marine clams, and freshwater mussels among many others, including sea urchins, corals, and even killer whales. Many species live quite long: some Pacific rockfish live well over 100 years, the Pacific geoduck clam can live to be more than 150 years, and freshwater mussels reach ages of more than 80 years.

By applying techniques from tree-ring science (dendrochronology), growth chronologies (analogous to tree-ring chronologies) can be developed for these diverse species. For example, we’ve developed 50-year rockfish chronologies and 120-year Pacific geoduck chronologies. Applications for these chronologies include 1) evaluating long-term growth trends, 2) establishing exact ages of all individuals in the sample, 3) comparing instrumental climate records to the chronology to establish the effects of climate on growth, and 4) for particularly long-lived species, reconstruct climate prior to the start of instrumental records. We can also compare growth patterns across very diverse species and ecosystems: trees in the forests vs. mussels in the rivers vs. marine clams in the nearshore, and marine fish on the continental shelf (see illustration below). Remarkably, these chronologies all relate to one another due to the strong influences of climate throughout these diverse ecosystems.

The diverse organisms for which chronologies have been developed, and the habitats they represent.

Ongoing Projects

Marine Ecology	splitnose rockfish (Sebastes diploproa) growth increments

Crossdating and chronology development in Pacific rockfish

Bryan Black, George Boehlert (OSU), and Mary Yoklavich (NOAA Southwest Fisheries Science Center, Santa Cruz)

thin section of a splitnose rockfish otolith

We demonstrate that climate induces synchronous growth patterns in splitnose rockfish otoliths (the “ear stone,” which forms annual growth increments analogous to those in a tree). This is important because every growth increment can be correctly identified by exactly aligning these growth “bar codes” among all samples. If an increment was accidentally missed or falsely added, the sample’s growth pattern would appear to be offset by a year relative to the others. The point where the offset begins indicates the location of the missed or falsely added ring. In this manner all growth increments can be accounted for and assigned the correct calendar year and age. This process of matching growth patterns among samples is known as crossdating, and is universally applied in dendrochronlogy (tree ring) studies. Because of crossdating, tree-ring chronologies are exactly dated and provide the annual resolution necessary for climate reconstructions. The same techniques may be applied for dating control in fisheries.

Amazingly, crossdating is possible in splitnose rockfish, even though the species lives at 300 meters depth, an environment often assumed to be largely unaffected by environmental variability. Crossdating is important for two reasons: 1) crossdating to the innermost increment will reveal the exact age of the fish, and 2) highly accurate growth chronologies can be developed and related to climate records, thereby quantifying the effects of climate on growth. Correct ages and climate-growth relationships are of critical importance for fishery managers. Rockfish can be extremely long lived – the above otolith is more than fifty years old, and many species of rockfish live to be more than 100!

Spatial and temporal variability of yelloweye rockfish growth in the northeast Pacific

Bryan Black, George Boehlert (OSU), and Mary Yoklavich (NOAA Southwest Fisheries Science Center, Santa Cruz)

We develop three crossdated growth-increment chronologies for yelloweye rockfish. One chronology is located along the north central California coast, another just north of Vancouver Island, British Columbia, and a final chronology on Bowie Seamount, near the BC and AK border. The three chronologies each extended approximately forty years and showed considerable variability on a range of timescales. When related to instrumental climate records, the southern chronology positively correlates with indicators of cool ocean conditions, while the two northern chronologies correlate with indicators of warm ocean conditions. Thus this study indicates an inverse production regime between the Gulf of Alaska and the California Current, as has been previously shown for salmon and primary and secondary productivity.

Relationships among somatic growth, recruitment, and climate in Acadian redfish

Bryan Black, George Boehlert (OSU), Ralph Mayo, and Jay Burnett (NOAA Northeast Fisheries Science Center, Woods Hole)

This ongoing project (currently in year 1 of 2) applies dendrochronology techniques to an Atlantic rockfish species sampled from the Gulf of Maine. Goals are to develop multidecadal growth chronologies and also use crossdating to validate fish age. This species has excellent records of recruitment, allowing for a comparison of the growth increment chronology with recruitment history and to evaluate whether the same climatic variables drive both indices of fishery productivity.

High resolution climate and recruitment reconstructions for Pacific geoduck

Bryan Black, Claudia Hand, Shayne MacLellan, and Darlene Gillespie (Fisheries and Oceans Canada, Pacific Biological Laboratory)

growth increments of a Pacific geoduck (acetate peel preparation)

Pacific geoduck are particularly long-lived, commonly attain ages of more than 120 years along the British Columbia coast, and support a multi-million dollar fishery for Washington, British Columbia, and Alaska. Using tree-ring techniques, we’ve been able to develop geoduck growth increment chronologies that date back to the 1880s. These chronologies strongly relate to sea surface temperatures (SST), and are an excellent proxy for SST data long before instrumental records were kept. Crossdating hundreds of geoducks also reveals a highly episodic recruitment history, with favorable recruitment conditions occurring only once every several decades. Pilot work for this project was completed at the Hatfield Marine Science Center by the 2006 North American Dendroecology Fieldweek, and NSF funded Research Experience for Undergraduates interns Rose Kormanyos and Matthew Stuckey.

Terrestrial Ecology	noble fir (Abies procera) tree rings

Freshwater mussels as indicators of stream flow and temperature

Bryan Black and Jason Dunham (USGS FRESC, Corvallis)

image of a freshwater mussel thin section

Although they’re becoming increasingly rare, a variety of freshwater mussel species occur in streams and rivers throughout North America. Amazingly, these organisms can live upward of eighty years, and perhaps even longer in the northern reaches of their range. Our research in Oregon shows that these organisms form annual growth increments that can be crossdated to develop chronologies spanning multiple decades. Preliminary chronologies strongly correlate with instrumental records of stream temperature and flow. Considering that instrumental records are uncommon, and those that do exist are short, freshwater mussel chronologies could significantly extend our knowledge of long-term environmental variability in streams and rivers throughout the state.

A 700-year climate reconstruction for the Browder Creek watershed, western Cascades, OR.

Bryan Black, Sarah Shafer (USGS Corvallis), and Rose Kormanyos (UC Davis)

Cutting wedges from old-growth Douglas-fir stumps

In this study, we salvaged wedges from Douglas-fir stumps remaining after a 1996 clearcut not far from the Andrews Experimental Forest. Almost all of the trees in the sample originated in the early 1300s, allowing us to develop an almost 700-year chronology. Wintertime weather in the western Cascades is heavily influenced by ocean conditions, and consequently the final chronology related strongly to Pacific sea surface temperatures, the Pacific Decadal Oscillation Index, and the Multivariate El Nino Southern Oscillation Index. This chronology provides a unique window into ocean variability over the past 700 years, and complements other long tree-ring chronologies developed on the east side of the Cascade Mountains.

The disturbance and disease history of a 400-year old coastal Douglas-fir forest

Bryan Black, Jeff Stone (OSU Plant Pathology), Dave Shaw (OSU Forest Science), and Bob Dziak (OSU)

Sampling an old-growth Douglas-fir

Over the past fifteen to twenty years, Swiss Needle Cast Disease has heavily impacted the productivity of coastal Douglas-fir forests in Oregon. This fungal disease is endemic to the Pacific Northwest, but only recently has inflicted substantial growth reductions. Our objectives are to determine whether these outbreaks have occurred in the past, and if so, with what severity and frequency. We address this issue using tree-ring data from an extraordinary 400-year old Douglas-fir forest along near the Pacific Coast. Another matter of interest is the effect of the massive 1700 Cascadian earthquake on the structure and function of the forest. This stand is one of the oldest in the region, and could provide a very rare opportunity to evaluate the degree of disturbance the ground motion caused in a forest community.