This is a repeat of a diary I posted two and a half weeks ago as part of my Sunday evening biodiversity series. For reasons foot-noted below* I am 'publishing' this diary again.
Just about a month ago I was privileged to attend, as a guest (rather than a participant) a conference devoted to developing a coordinated research program to measure the impact of the BP oil disaster on Gulf of Mexico coastal ecosystems. I'm going to attempt to give you an overview of the main points and show you some pictures to go along with them.
Beach in Panama City, Florida in fall 2008. This was the easternmost point (that I know of) where oil came ashore during June 2010.
A couple of notes about what this diary is not. It is not about assigning blame - it is designed to be informative rather than judgmental. It is also not about the current location of oil left in the gulf. The conference focused solely on coastal systems and I don't have any information about the offshore situation. I'm mostly trying to provide some things for people to think about in terms of how we should go forward.
I wrote pages and pages of notes but I don't want to make this diary too long or detailed. I'm going to aim for the big picture - here are some general points.
- Gulf ecosystems need more study. Surprisingly, for such a large area that is close to major population centers very few areas of the gulf have been the subject of long term studies. Two issues arise out of this. First, with areas being studied, the oil was unlikely to hit those areas (as it turns out, back in May when most of these people geared up to start studies they assumed, like everyone else, that the oil would be arriving along much of the northern Gulf coast within weeks). Time after time during the conference someone would half in jest ruefully note that they had gathered a bunch of data on a site in preparation for the oil and then the oil never arrived.
Boom at St. Marks National Wildlife Refuge in May 2010. Oil has not reached this area.
Second long term data is needed. Most natural systems are quite variable and without long term data both before and after the incident (in this case an oil spill)it can be difficult to separate effects of the spill from year to year variation. Obviously if there are catastrophic effects they are easily detectable but more subtle ones could easily be misinterpreted. If the oil spill happens to hit just when the population is going down then the effects are likely to be overestimated. Or if the spill happens when the population is rising then the effects may be underestimated. If you have years of data both before and after the spill then you can sort out the effect of the spill from the environmental 'noise'.
For example, the productivity of oyster beds is highly variable from year to year. All the factors influencing this variability are not understood but one big one is fresh water input (i.e. amount of rain upstream from the estuary). This decreases the productivity the following year but increases over the next several years after that. One response in Louisiana to the oil threat was to release extra freshwater into the marshes in an attempt to keep the oil out. This is likely to decrease oyster populations next year and it will be difficult to separate that out from the effect of the oil.
Oysters form their own substrate which, in turn, provides a home for other organisms.
2)There is little relevant data on the ecological effects of oil spills. This may sound surprising but apparently there are lots of short term studies but very few that follow oiled sites over long periods. One in Massachusetts found that the salt marsh appears normal to the eye some 40 years later but productivity is still lower than normal. The Ixtoc spill in Mexico was the subject of a number of studies funded by the Mexican government that were never published.
Mangroves are an abundant coastal habitat in tropical and subtropical environments. Little is known about the impact of oil on mangroves despite major spills occurring in mangrove rich areas.
Mangroves are an important source of nutrients and shelter for many animals. Here manatees graze on algae growing on the prop roots.
- The Gulf of Mexico has variable coastal habitats some of which are much more common here than in general in the world's coastal areas. The two specifically mentioned as being very abundant in the Gulf are barrier islands and sea grass beds (both of these obviously occur elsewhere). Some of the habitats have been extensively studied (e.g. salt marshes) while others (barrier island systems) are not as well known. Many of these habitats have highly valuable properties. Sea grass beds are a globally important carbon sink. Salt marshes and mangroves offer coastal protection, filter nutrients and provide breeding areas for many economically important forms of marine life. Others like barrier islands and beaches are important to humans for recreation. They are nutrient poor areas that rely on nutrient input from the ocean and from birds that move between environments.
Back side of St. Vincent Island. The low tidal scope of the area often results in large barrier islands with extensive vegetation. These habitats are little studied.
Lubber grasshopper on St. Vincent. The role of herbivores on these nutrient poor, highly disturbed habitats should be studied in more detail.
Relatively few studies have been made of the food webs of barrier islands.
Dune vegetation on St. George Island
Sea grass washed up on a beach in May 2010 following a storm. This is an important source of nutrients for beach organisms which is often removed by people in order to keep beaches clean.
- The effects of the oil can be evolutionary as well as ecological. Exposure to the oil and dispersant is a major event of natural selection. Individuals that are more tolerant of the chemicals are more likely to survive and thus the genetic makeup of populations will change. One researcher has been studying the short and long term changes in gene expression in fish populations that live in superfund sites in the northeast. He is now moving to look at a closely related species in areas before and after the arrival of oil.
Salt marsh vegetation and fiddler crabs. Exposure to oil will likely result in the increase in oil resistant genotypes in a wide variety of species.
- Crude oil is a very complex substance and the persistence and toxicity of the different parts is going to vary greatly. Sampling should take this into account. One fascinating fact I learned as part of this talk was that oil contains compounds that are virtually identical to hemoglobin and chlorophyll with the reactive metal group (iron and magnesium respectively) being replaced by another metal. This was apparently how it was determined that oil was of biological origin. So oil contains fossilized blood!
- Studies of the oil on the beach in Pensacola have shown that it has been drawn about two feet under the surface of the beach. Partly this is due to deposition of new sand but mostly due to the wave action acting as a pump to draw the oil down through the sand. Oxygen consumption is high at the oil layer indicating high microbial activity, identified as particular types of oil consuming bacteria. It will take time to see how rapidly they consume the oil.
Although the sand may look barren, lots of things live in it, both above the water and below. This stingray buried itself within a couple of seconds of my taking this picture.
- It is important to coordinate studies so that individual researchers don't replicate work by others and multiple people can collect complementary data in the same sites. Consistent sampling should be done regularly over a number of geographically distinct sites. It is kind of amazing that this was not being done before the spill.
Pelicans at St. Andrews State Park, Panama City, September 2010. Birds are an important source of nutrient movement between ecosystems. Although bird populations are generally well monitored their effects on ecosystems are not as well known.
- It is important to sample the most vulnerable components of the ecosystems. For example the plants that make up sea grass beds are fairly resistant to oil as long as they aren't smothered with a heavy layer. However, many of the animals are likely much more sensitive but, because they are less common and obvious (and move around) they aren't studied to the same extent.
Clapper Rail and chick, a characteristic species of salt marshes. Much less obvious than a pelican or dolphin because of secretive habits.
Horseshoe crabs mating in St. Joe Bay. This area has extensive sea grass beds and is an important breeding ground for many marine animals. Although the sea grass itself maybe resistant many of the animals are very vulnerable.
So the take home message is more consistent and long term sampling and coordination among researchers.
The lack of knowledge is widespread in studies of biodiversity. For most groups of organisms we just don't know what is out there. I hope to go back to St. Andrew's State Park in Panama City once more this fall and attempt to record the diversity of as many species as I can in a systematic fashion. The jetty there supports a rich variety of marine life.
The number of species in one place can be overwhelming.
And made more complicated by the fact that many species move around a lot. This tang's parents probably live on reef in Mexico. As a larva this fish was carried north. It will be informative to see if recruitment of new reef fishes changes between years.
Filter feeders may be very sensitive to toxins in the water which may not bother the fishes.
Some of the toxins may bioaccumulate in top predators like this barracuda.
Many people at this site have talked about citizen science. This is something you can do. Studies of the biodiversity of organisms at almost any site have value. Long term studies have even more. As this series progresses I'd like to think about interested 'amateurs' can help monitor our biodiversity.
*This was the third diary in my 'A More Ancient World Series' and it generated considerably less interest than any of the others. whaddaya, my fellow regular at 'Dawn Chorus' urged me to repost at a time when there would be more traffic. I'm not completely content with Sunday evening as a regular diarying time so I thought I would give Wednesday a try.