Hypothesis

Are Seabirds Changing? Are the Oceans Changing?

Are seabirds and oceans changing? Why? How? What are the relationships? Are some ocean changes causing some seabird changes? Are seabirds good indicators of ocean changes? Is there anything we should do, can do? This paper looks at some seabird changes, especially the highly visible Razorbill changes, and hypothesizes the mechanism for this, and then searches for some published evidence which might support the hypothesis.

The working hypothesis consists of the following points:

1. The planetary atmosphere is warming, on the average, although we will not try to explain why... that is outside the scope of this article.
2. Atmospheric warming (along with plenty of sunlight) leads to ocean warming. Some percent of the atmospheric heat is absorbed by the ocean. There is an exchange and equilibrium of heat (and gases) between the atmosphere and the ocean.
3. Areas of abnormally high tidal mixing (such as the Bay of Fundy)  are able to absorb more "excess" atmospheric heat (which upsets the thermal equilibrium between the atmosphere and the seawater) more rapidly than most of the ocean, acting as an unusually effective gas-liquid direct contact heat-exchanger, partly because of the extreme tidal turnover, breaking thermal stratifications, bringing up cold waters from the deep and exposing it to the increasingly hot air, to absorb an unusually large percent of that abnormal heat from the air and circulate it rapidly down to the depths, and then tidally to transport it (200 billion tons of water) out to the wider Gulf Of Maine twice daily. Most other areas of the ocean rely on natural convection and will not have this extreme tidal mixing (forced convection), and will be able to absorb less of the excess and increasing atmospheric heat. This mechanism may be a significant contributor to the above-average 2012 warming of the Gulf of Maine and the nearby western North Atlantic.
4. Ocean warming changes many marine components, including causing unusually early spring phytoplankton blooms, as in 2012.
5. These changing phytoplankton blooms may be too-early for optimum zooplankton utilization, reducing the zooplankton's success and abundance in some areas, in some months.
6. Zooplankton reductions impact its many predators which depend directly upon it, such as larger zooplankton, small fish and some smaller seabirds. Reductions in small and larval fish (such as sand lance, capelin, hake and especially Atlantic herring, which is the Razorbill's primary prey species) reduce the breeding success of many seabirds, including Razorbill (Alca torda), and may reduce Cod and the larger fish which prey on the small fish and their larvae.
7. Razorbills are a very "dispersive" species ( see Gaston & Woo, 2008 article ), and strike out in search of new feeding grounds when their supplies of small fish are greatly reduced. That makes them an unusually good "indicator species", quickly reflecting changes in their environment.
8. Some Razorbills, some of which are normally year-round permanent residents in the warmer southern end of their range (including some in the GOM Gulf Of Maine), experienced a lack of suitable food items for the first time in their life, and headed south for the first time, looking to find food. Additionally, some more northerly Razorbills which normally would winter in the GOM probably found few herrings there in December and kept migrating south, ending up in Florida waters.
9. With little experience with such winter movements, however, this subset of the Razorbill population once moving south found little food and did not know when to stop. Their dispersive tendencies pushed them to travel  further south until they reached Florida and Gulf of Mexico waters, with many probably dying there from lack of enough suitable food.
10. The following year (2013) there were many fewer Razorbills to report on Christmas Bird Counts, from the southern edge of their normal range (because so many of the birds from this permanent resident population had migrated to Florida and probably perished over the 2012-2013 winter).

Learning more about this marine ecosystem and its interdependencies will help us test this multi-point hypothesis and more generally understand, anticipate and adapt to the many changes in our global and local environment. Birder observers, the fishing community and marine scientists of all kinds are collaborating more to advance our understanding of and preparedness for these changes. Birders can do this as "citizen scientists" or simply by contributing their field observations to eBird, Christmas Bird Counts, etc.  As our environment continues to change, it is more important than ever that we work together on these matters.