Ecotoxicologists: heed this advice!

As my readers likely know by now, seabirds are often used as bioindicators of contaminants in aquatic ecosystems. Such studies rely on the fact that contaminants are ingested through contaminted prey so that contaminants in seabirds are reflective of the local diet - and ecosystem. But it turns out that linking contaminant exposures to diet in seabirds is more tricky then  many biologists realize.

A recent paper by Alexander Bond discusses the utility - or futility - of comparing diet and contaminant signatures within feathers of seabirds. Such studies often rely on stable carbon and nitrogen isotopes to evaluate diet.

Asian Carp are knocking at the (electric) fence

It's been sometime since this blog has talked about looming threats to the Great Lakes Basin. Unfortunately the reality is that there continues to be a multitude of environmental issues knocking at the locks- or in this case, the electric fence barrier in Chicago.

A couple species of exotic and invasive Asian Carp have made their way up the Mississippi River and are posed to get into Lake Michigan via the Chicago Lock's. The threat has alarmed everyone from scientists to fisherman and recreational boaters because once into the lake, this fast-growing filter feeder would severely disrupt phytoplankton production and potentially cripple the commercial and sportfish industries. To boot, the Asian Carp responds to danger (i.e. boat engines) by jumping out of the water, sometimes injuring boaters. Imagine water skiing and having to dodge jumping fish!

The voracious plankton feeders wer first introduced to fish aquaculture pens down in Arkansas to control algae blooms and parasites, supposedly 'improving water quality'. Unfortunately this has become a classic example of biological introductions gone wrong.

Every spring during reproduction, birds have a decision to make: should they use nutrients derived locally for egg production, or use reserves transported to the breeding ground? Well, it's actually not so much a choice as it is a matter of species life history.  But for aquatic toxicologists, knowing what strategy a species prescribes to is critical if one chooses to sample eggs for contaminant analysis.

A pathway for contamination

Common terns are obligate piscivores, meaning they feed almost exclusively on fish. What this also means is that they are near the top of the food chain and at high risk to contaminants that biomagnify  from one trophic level to the next. Polychlorinated Biphenyls (PCBs) are one of these biomagnifying contaminants, and to date no study has elucidated the biological pathway of PCBs from their discharge into the environment to ultimate accumulation in terns.

A recent study by M. Ward from the University of Illinois has attempted to describe this biological pathway using a population of common terns breeding within a naval station harbour on Lake Michigan, Illinois. Terns are endangered in Illinois and because PCBs can impact fitness, reduce reproductive success, and in some cases lead to mortality, it is useful to understand how they accumulate in terns.

29th annual Colonial Waterbird Meeting

Last week was the 29th annual meeting of the Great Lakes Area Working Group on  Colonial Waterbirds (GLAWGCW). Having just recently begun my own research on colonial waterbirds in the the Great Lakes, this was my first year in attendance. Overall, it was a great experience because I was able to meet other biologists working on similar research and the meeting provided a platform to  share our work and discuss important population trends for colonial birds in the lower Great Lakes.  And I have to say that I find considerable satisfaction in knowing that some old bearded biologists have dedicated the last several decades to colonial waterbird monitoring in the Great Lakes.

Aquatic Toxicity Workshop 2010

I just recently returned from the Aquatic Toxicity Workshop, held this year in Toronto, Ontario. The four day conference is designed to bring industry, private consultants, and academics together to present and discuss new research in aquatic toxicology. Toxicology is the study of poisons (or contaminants) and aquatic toxicologist study the movement of these contaminants through aquatic ecosystems. This year the theme was, "Big cities - Big challenges - Great solutions: urbanization and environmental impacts".  The theme was specific, but the talks spanned a much wider range of issues from contaminants leeching out of the Alberta tar sands, to the impacts of pesticides and herbicides on forest-dwelling amphibians, to the impacts of migration on mercury loading in birds.

Farming for terns!

Common terns are small colonial nesting seabirds that some might say are the most graceful here in our freshwater paradise of northeastern North America. Although their population is only a fraction of what it used to be in the Great Lakes, recent management actions in the U.S. and Canada have helped to maintain several healthy colonies. Historically, terns in the Great Lakes nested on small rocky islands or shoals, but in recent decades they have come to be more and more dependent on the 8m diameter Seaway Navigation Cells (channel markers).

This spring, before beginning my research on contaminants in terns,  I had the opportunity to help out Lee Harper, the lead biologist for the Upper St. Lawrence River tern management initiative. Most of his work is behind the scenes (i.e. before the terns arrive each year in late April), spending several days out on the water improving habitat at most of their known nesting sites. Habitat improvement projects require knowing in advance what habitat features terns prefer. And like any good management plan, decades of scientific observation and experimentation have realized several key features of good tern habitat.

Because terns are relatively small seabirds for the Great Lakes, they require a good degree of isolation and protection from would-be predators like gulls and herons. In addition to the isolation of nesting on rocky shoals and navigation cells, they tend to favor sites with fine substrate such as pea-gravel to form their nests on the ground. But first, because the gulls return to the breeding grounds about a month before the terns, we set up mono-filament exclusion grids that prevent the wider wingspan of a gull from landing on would-be tern habitat. We also put out several “chick shelters” that offer protection from potential predators and a shady place for young chicks to rest during the hot summer days. Lastly, we put up 30cm tall mesh fencing around the edges of the colonies so that chicks don’t jump into the water and get washed downstream before they are old enough to fly back.

Once all these things are in place for the breeding season, we get to wait for a few weeks as the terns slowly arrive on the breeding grounds and begin to find their mates and choose a suitable territory within the small colonies. Then the real fun begins of monitoring reproductive success and banding chicks...I’ll talk more about this in a later post when I discuss my research in more depth.