Category Archives: Foci

Blue Carbon Initiative: mitigating climate change in the oceans

Listened to this webinar, “Blue Carbon Ecosystems – what’s included, what’s not and why,” by Jenna Howard and Ariana Sutton-Grier about the Blue Carbon Initiative and climate change mitigation to understand how terrestrial carbon sequestration rates compare with those in marine ecosystems.  This talk focused mostly on coastal marine habitats with the best potential — mostly in-air plants (mangroves, marshes) and also seagrass beds.  Here is a video recording

and some of my notes/screengrabs:


Their paper has a more detailed table with equations, sources, etc.

Their paper has a more detailed table with equations, sources, etc.

link to paper — Clarifying the role of coastal and marine systems in climate mitigation

For comparison, humans activities put about 7000 million Mg C yr^-1 into the atmosphere.

Or 7 Gt/yr.

Mitigation potential (and feasibility)

Mitigation potential (and feasibility)

Mangroves and marshes

Range of uptake rates

  • vegetative carbon: 8-126 tons/ha
  • soil carbon: 250-280 tons/ha
  • ratio shows that 2-30 time more carbon is in soil than in vegetation
  • sequestration rate: 2.1-2.6 tons/ha/yr

Global loss of these habitats is ~1.5-2%, so half of habitat gone in 35-50 years


Long-term effect of calcification in coral reefs: a slight net source of CO2, but could reverse if ocean acidification increases dramatically

Dissolution process takes CO2 out of water column.

Take home message: no red arrow, meaning coral isn’t a climate change mitigation option


Most kelp gets consumed or degrades in days, months, or at most a couple years

So, it’s a temporary carbon pool, not a long term storage option


Only 0.1% sinks to ocean floor for long-term storage, but the area is HUGE compared to the geographic extent of the coastal ecosystems.

BUT, it’s not in the running due to policy issues that have been (and are) challenging…

  • who manages, owns carbon sequestered, etc.
  • ethics of seeding with bioengineered cultures (didn’t even mention fertilization)

Screengrab from webinar

Screengrab from webinar

Marine fauna

Calcifiers (e.g. pteropods), krill, teleost fish (feces contain CaCO3 but doesn’t sequester, only affects alkalinity gradient)





My related notes from beyond the webinar:

What is sequestration rate for terrestrial ecosystems (temperate vs tropical forests)?

The Blue Carbon Initiative web site says of marine/coastal ecosystems:

“These ecosystems store up to 10 times more carbon — called “blue carbon” — per hectare than terrestrial forests, and degradation of these ecosystems accounts for up to 19% of carbon emissions from global deforestation.”

Why not great (baleen+sperm) whales as long-term sequestration?  Estimate potential using listed species population assessments and historical baselines?

If we protect and enhance their habitat to maximize their growth rate, how many new whales could be added to the global marine ecosystem each year?

Back of the envelope:

Let’s say blue whales are ~100,000 individuals below carrying capacity (it’s likely closer to 200,000) and each adult whale constitutes a sink of ~100 Mg of carbon (assuming they’re mostly lipid-rich blubber = hydrocarbons).  If the extant population (currently <10,000 whales growing at 8%/yr) manages to add 1,000 new blue whales per year, that would sequester 100,000 Mg/yr.  Maybe multiply that by 10 for other baleen whale species (blue, fin, right, humpback, sei, grey, bowhead, Bryde, minke, Omura/Eden, sperm) of similar mass that are similarly below carrying capacity and we’re at 1 million Mg/yr.  That estimate might be high or low by a factor of ~10 given the uncertainties.  Either way, 1 million Mg C yr^-1 is within the range of interesting numbers listed in the table…

Assuming recovery of the globe’s baleen whale populations takes 100 years, we could expect over that time period an increase in the amount of carbon stored in living whales of about 100 million Mg C.  That’s comparable to the biomass of all phytoplankton (0.5-2.4 billion Mg C, according to their paper and it’s citations).  Then there’s the flux (from dead adult whales) into the deep sea, where it would be sequestered for order 100 years…

It looks like famous folks have already pondered most of this:




Email announcement:​​

Blue Carbon Ecosystems – what’s included, what’s not and why



Wednesday, February 8, 2017, 2pm – 3pm EST

REGISTER online at


Webinar Summary:

With increasing recognition of the role natural systems have in climate mitigation, where should management initiatives focus? While forest have historically had the spotlight of such efforts, coastal wetland ecosystems are now considered important and effective long-term carbon sinks. This attention to “blue carbon” habitats has sparked interest in including other marine systems, such as coral reefs, phytoplankton, kelp forests, and marine fauna.

In this webinar, authors of a recently published paper – Clarifying the role of coastal and marine systems in climate mitigation (Frontiers in Ecology and the Environment, Feb. 2017) – analyze the scientific evidence and potential management role of several coastal and marine ecosystems to determine which should be prioritized within current climate mitigation strategies and policies. Findings can assist decision-makers and conservation practitioners to understand where management actions can have additional carbon benefits.



Dr. Jennifer Howard and Dr. Ariana Sutton-Grier

Dr. Jennifer Howard is the Marine Climate Change Director at Conservation International. Prior to accepting her current position, she was a AAAS Science and Technology Policy Fellow where she served two years at the National Oceanic and Atmospheric Administration’s (NOAA) National Marine Fisheries Service. While at NOAA, Jennifer co-led and coordinated the development of the Ocean and Marine Resources in a Changing Climate Technical Input Report to the National Climate Assessment and coordinated the Interagency Working Group for Ocean Acidification.


Dr. Ariana Sutton-Grier is an ecosystem ecologist with expertise in wetland ecology and restoration, biodiversity, biogeochemistry, climate change, and ecosystem services. Dr. Sutton-Grier is a research faculty member at the University of Maryland in the Earth System Science Interdisciplinary Center and is also the Ecosystem Science Adviser for the National Ocean Service at NOAA.  She holds Honors Bachelor degrees from Oregon State University in Environmental Science and International Studies and a doctoral degree from Duke University in Ecology.


Moderator: Stefanie Simpson, Blue Carbon Program Manager, Restore America’s Estuaries (and paper co-author)


This free webinar is hosted by Restore America’s Estuaries.

Chinook salmon and southern resident killer whales occupy similar depths in the Salish Sea

New paper by UW colleagues entitled “Interpreting vertical movement behavior with holistic examination of depth distribution: a novel method reveals cryptic diel activity patterns of Chinook salmon in the Salish Sea” shows some results from Vemco receivers I deployed in the San Juan Islands. Young adult Chinook favor depths less than ~30 meters, with some seasonal variability in their diel activity patterns. Overall, they go deeper and vary more in the depths at night.

Dive profiles for two Salish Sea Chinook salmon during the summer and fall.

Dive profiles for two Salish Sea Chinook salmon during the summer and fall.

Interestingly, according to a report to NOAA/NWFSC by Baird et al, 2003 (STUDIES OF FORAGING IN “SOUTHERN RESIDENT” KILLER WHALES DURING JULY 2002: DIVE DEPTHS, BURSTS IN SPEED, AND THE USE OF A “CRITTERCAM” SYSTEM FOR EXAMINING SUB-SURFACE BEHAVIOR) SRKWs spend >97% of their time at depths of less than 30m.

This suggests any future deployment of horizontal echosounders should aim to ensonify a depth range centered on ~25m (e.g. 5-45m or 10-40 m).  Compared to the estimated orientation and surveyed depth range of our 2008-9 salmon-SRKW echosounder pilot studies, we may want to measure inclination more carefully to (a) center the survey on the mean summertime depth range of Chinook and (b) avoid ping reflections from surface waves, boats, and bubbles (which may have confused interpretations of targets >100 m from the transducer).  Here’s my diagram for the situation in 2008-9 in which we were centered on 15 m and ensonified a maximum depth range of ~0-30m (in other words, we may have been aiming a little high):

Screen grab from the 2009 ASA presentation showing echosounder geometry

Screen grab from the 2009 ASA presentation showing echosounder geometry



Southern resident growth rate ambiguity

About a month ago Orca Relief issued press releases related to the population dynamics of southern resident killer whales.  I spent a little while then marveling at how their new leader Bruce Stedman seemed to have cherry picked data with which to support a claim that the population was in precipitous decline.  This morning I took some time to revisit those plots in light of the equally disturbing statistics and graphs presented during the orca-salmon workshops conducted by Will Stelle over the last couple years (live blogs with audio and/or video here — workshop 2; workshop 3).

Basically, somebody who is statistically-talented and politically-independent needs to clarify for the conservation and stewardship community the state of the Southern Resident killer whale (SRKW) population.  The same person or entity should re-interpret the data whenever we get an updated census (from the Center for Whale Research [CWR] which — as an aside — recently put its NOAA-funded photos and census data behind a membership paywall).

The main misleading aspects of the Orca Relief plots (see below) are that they only went back to 1997 (though we have data back to 1971) and they focused on decreases in juvenile and reproductive females that were drawn from maxima in the time series, rather than being fit to the full range of data.  This is an incomplete statistical presentation, and one that is potentially misleading, just as using stacked bar graphs can cause confusion in any science presentation.  Below are two examples.

Female SRKWs of (undefined) reproductive age by pod.  Stacked bar graphs make it difficult to see and compare trends in the K and L populations; only the J and total population trends can be easily discerned.

Juvenile female SRKW population time series as presented by Orca Relief.  The rate of decline from 2001 to present is an overestimate of decline compared with one made using 1997 to present, or a best linear fit to all available data.  More importantly, why have the previous, available 22 years of data been excluded?

For comparison, here is a plot of all CWR census data (1971-2012) by pod as presented in the 2012 Puget Sound Partnerships orca vital sign:

CWR SRKW population data by pod presented by the PSP.

CWR SRKW population data by pod presented by the PSP.

This shows how potentially misleading it is for an organization like Orca Relief to showcase trends using only data since 1997!  If we use 1971 as the baseline, J and K pod appear to have grown slowly, while L pod’s growth is positive but lower.  It also is apparent that the population dynamics of L pod, more than J or K, drive the sudden changes in the total population, which is growing on average over the whole time series.  As the 2012 PSP’s orca vital sign reports:

“…as of July 1st 2013, the size of the population was 82 individuals, down by four whales relative to the 2010 baseline reference of 86 whales… Although there has been no progress made since 2010, the population has been growing, albeit slowly at about 1% per year, over the longer term (1979 to 2010).”

The stories run by Q13FOX, the San Juan Islander and Island Guardian and picked up by KOMO news didn’t concern themselves with such statistical details.  However, a later piece in the San Juan Islander about reproductive (mature) male SRKWs quoted NOAA’s Eric Ward who argued that the recent decline in mature males is part of the population’s historic fluctuations, not a sign of imminent collapse as suggested by Orca Relief in the Island Guardian.  Both pointed out the good news: that juvenile male populations have been rising recently.

Mature male time series portrayed by Orca Relief (1997-2013)

Juvenile male increase graphed by Orca Relief

Eric Ward's plot of mature male SRKW population (1971-2013)

Eric Ward’s plot of mature male SRKW population (1971-2013)

As an aside, I was impressed that the San Juan Islander provided references to some of Eric Ward’s papers.  What wasn’t referenced though, were the many discussions of SRKW population trends in the 3 NOAA-sponsored workshops on “The Effects of Salmon Fisheries on Southern Resident Killer Whales.”  In the third workshop, it became clear that Ward presented estimates of population growth rates for the SRKWs (basically +1% annual growth rate) which were at odds with estimates made by his Canadian modeler-analog Antonio Velez-Espino (basically -1% annual growth rate).   (Velez-Espino chose to exclude pre-1987 data, stating that his choice — a compromise between extent and quality of data — was most representative of the current population ~25 years or one generation back.)

So, is the SRKW population in slow decline or slow recovery?!  How concerned should we be with the latest downturn in the overall population?  What does it mean for the recovery process if the population continues to fail to meet the recovery plan goal of maintaining 2.3% annual growth over a period of 14 years?

The final report from the orca-salmon workshops (Hilborn, Cox, Gulland, Hankin, Hobbs, Schindler, Trites, 2012) has some exemplary figures that shed a little more light on the situation, particularly the trends in the population of juvenile females (J pod increasing, L pod decreasing).  Note that the break points between Orca Relief’s and the Science Panel’s juvenile/young and breeding/reproductive age classes are different.  Nevertheless, it’s worth focusing on the  juvenile and reproductive female age groups because they have a strong influence in population models like Velez-Espino’s.  (He stated in the final workshop that the greatest increase to the modeled population growth rate comes from increasing survival and fecundity of young reproductive females.)  Below are figures for “young” (<21 year old) and “young and reproductive” (<43 year old) populations (not directly comparable to the age groups chosen by Orca Relief, but similar).

Young (<21 year old) SRKW population trends

Young (<21 year old) SRKW population trends and sex ratios.

Mature SRKW population trends

Young and reproductive SRKW population trends

So, out of time again, I’m left wondering: should we be panicking as the strange year of 2013draws to a close?  What do you think?


Hilborn, R., Cox, S. P., Gulland, F. M. D., Hankin, D. G., Hobbs, N. T., Schindler, D. E., & Trites, A. W. (2012). The Effects of Salmon Fisheries on Southern Resident Killer Whales Final Report of the Independent Science Panel (p. 87). NMFS & DFO. Retrieved from