I had an exciting day. Really. And you all need to be more educated about the hudson river. I would add photos, but they mostly look like mud, and mud just ain't too exciting unless you're a marine biologist. And even then, it stinks.
Assessing Biodiversity in the Hudson River Estuary
New York Harbor is under attack. Its piers, pilings and bulkheads are built largely of wood, and currently they are falling victim to, paradoxically, the dramatic improvement of water quality in the Hudson River over the past few decades. As these structures are destroyed, a vast surface, occupied by millions of marine creatures will be lost. When they are replaced, we want to know what species will recolonize them, and how quickly.
Throughout most of the past century, untreated sewage has been discharged directly into the river. Combined with other factors such as overfishing and agricultural runoff, this has had a significant negative impact on its biodiversity. Recognition of this problem and legislation such as the Clean Water Act of 1972 has led to improved water quality control and management, and the return of many organisms previously missing from the river’s subtidal communities demonstrates some measure of success.
Two organisms with a particularly conspicuous return have been the shipworm, Teredo navalis and the gribbles Limnoria lignorum and L. tripunctata; these are marine borers that are slowly destroying all wooden structures in New York Harbor. As a result, most of these structures will need to be replaced in upcoming years, and it is important to choose materials that attract marine animals and plants, which will enrich the harbor ecosystem. On the other hand, such materials have to be resistant to chemical and biological destruction.
The goal of one current study at The River Project is to assess the biodiversity and patterns of colonization of subtidal organisms in the river. Work began in the summer of 2002 with the deployment of a series of terra cotta tiles suspended just below the low tide line from the edge of the bulkhead at Pier 26; it continued this past summer on a larger scale. Additionally, tiles made from materials proposed as potential candidates in the rebuilding of the harbor – an anti-fouling polymer coated steel, concrete, and plastic – were deployed late in the summer of 2003. Photographs documenting the colonization of the tiles have been taken every week throughout their deployment. The good news is that colonization is rapid and we have found over 30 species on the plates, most arriving as planktonic larvae. Lower New York Harbor is biologically vibrant.
A number of factors have been shown to influence the colonization of subtidal substrata; the first of these is the nature of the substrate itself. Certain substrata may be more attractive to settling larvae than others. For example, preliminary data already show that concrete is more attractive to settlers than, unsurprisingly, steel that is coated with an anti-fouling polymer. The orientation of a substrate and the flow of water over it can also have an effect on colonization; larvae are largely dependent on water currents for transport and water flow over the substrate will determine if larvae successfully encounter a potential settling site. Furthermore, over the course of the study it has become apparent that flow can also significantly affect the accumulation of sediment, even on vertical surfaces. The Hudson River is very turbid, and quiet water allows the particles to settle and accumulate. Variation in sedimentation appears to affect differences in community profile; certain organisms such as the worm Polydora ligni seem to thrive in the mud while others, particularly filter feeders such as the barnacle Balanus fragilis do not fare nearly as well. Still other organisms like the solitary ascidian Molgula manhattensis do not appear to be affected either way, although the data have not yet been analyzed to determine any statistical differences.
Another factor that has been suggested to have an effect on colonization is the presence of adults of a particular organism; for example the larvae of some species may tend to settle near adults because the adults indicate a favorable environment, or because the adults themselves serve as an attractant. In the oyster Crassostrea virginica, adult oysters create a habitat with enough three-dimensional structure that vulnerable juveniles can avoid predation. The oyster, which once densely populated New York Harbor, has been absent for many years due to depleted oxygen levels caused by pollution. For the past five or so years, it appears to have been making a tentative reappearance in a few areas around the harbor, including on the pilings at The River Project. During this past summer, a total of three oysters were counted on the seventy-two terra cotta settling plates; two of the individuals were on the exposed surfaces of plates and grew to a length of about 25mm before dying. The remaining individual was in a protective crevice created between the plate and the frame holding it; future research may help elucidate what factors allow oysters to survive in the river.
Many species of fish long absent from the harbor, including those valuable to commercial and sport fishermen such as the sheepshead, Archosargus probatocephalus, are attracted to oyster beds. Oysters, and other filter feeders such as barnacles and mussels, are also capable of filtering large volumes of water; clearly, the ecology of the harbor in the future will be substantially affected by whether the materials used in its construction are conducive to settlement. Research may help in the choice and design of these materials; for example, the knowledge that larvae are attracted to concrete and have increased survivorship on surfaces with a texture that provides protection may help in the design of harbor structures that promote the development of healthy reefs.
Another interesting feature of current biodiversity in the river that the study may help clarify is the role that introduced species play in shaping subtidal communities. The lacy bryozoan Membranipora membranacea, which was first introduced to the east coast in the Gulf of Maine in 1987, and the golden star tunicate Botryllus schlosseri, which was introduced to Newfoundland from Europe, have both since spread all along the east coast of the United States, including to the pilings of Pier 26. Both of these species have been shown to have detrimental effects in other ecosystems such as the kelp beds of Nova Scotia and Monterey Bay, CA; the current research at the River Project may aid in determining what effect these non-native species will have on current and future biodiversity in the Hudson River.
Assessing Biodiversity in the Hudson River Estuary
New York Harbor is under attack. Its piers, pilings and bulkheads are built largely of wood, and currently they are falling victim to, paradoxically, the dramatic improvement of water quality in the Hudson River over the past few decades. As these structures are destroyed, a vast surface, occupied by millions of marine creatures will be lost. When they are replaced, we want to know what species will recolonize them, and how quickly.
Throughout most of the past century, untreated sewage has been discharged directly into the river. Combined with other factors such as overfishing and agricultural runoff, this has had a significant negative impact on its biodiversity. Recognition of this problem and legislation such as the Clean Water Act of 1972 has led to improved water quality control and management, and the return of many organisms previously missing from the river’s subtidal communities demonstrates some measure of success.
Two organisms with a particularly conspicuous return have been the shipworm, Teredo navalis and the gribbles Limnoria lignorum and L. tripunctata; these are marine borers that are slowly destroying all wooden structures in New York Harbor. As a result, most of these structures will need to be replaced in upcoming years, and it is important to choose materials that attract marine animals and plants, which will enrich the harbor ecosystem. On the other hand, such materials have to be resistant to chemical and biological destruction.
The goal of one current study at The River Project is to assess the biodiversity and patterns of colonization of subtidal organisms in the river. Work began in the summer of 2002 with the deployment of a series of terra cotta tiles suspended just below the low tide line from the edge of the bulkhead at Pier 26; it continued this past summer on a larger scale. Additionally, tiles made from materials proposed as potential candidates in the rebuilding of the harbor – an anti-fouling polymer coated steel, concrete, and plastic – were deployed late in the summer of 2003. Photographs documenting the colonization of the tiles have been taken every week throughout their deployment. The good news is that colonization is rapid and we have found over 30 species on the plates, most arriving as planktonic larvae. Lower New York Harbor is biologically vibrant.
A number of factors have been shown to influence the colonization of subtidal substrata; the first of these is the nature of the substrate itself. Certain substrata may be more attractive to settling larvae than others. For example, preliminary data already show that concrete is more attractive to settlers than, unsurprisingly, steel that is coated with an anti-fouling polymer. The orientation of a substrate and the flow of water over it can also have an effect on colonization; larvae are largely dependent on water currents for transport and water flow over the substrate will determine if larvae successfully encounter a potential settling site. Furthermore, over the course of the study it has become apparent that flow can also significantly affect the accumulation of sediment, even on vertical surfaces. The Hudson River is very turbid, and quiet water allows the particles to settle and accumulate. Variation in sedimentation appears to affect differences in community profile; certain organisms such as the worm Polydora ligni seem to thrive in the mud while others, particularly filter feeders such as the barnacle Balanus fragilis do not fare nearly as well. Still other organisms like the solitary ascidian Molgula manhattensis do not appear to be affected either way, although the data have not yet been analyzed to determine any statistical differences.
Another factor that has been suggested to have an effect on colonization is the presence of adults of a particular organism; for example the larvae of some species may tend to settle near adults because the adults indicate a favorable environment, or because the adults themselves serve as an attractant. In the oyster Crassostrea virginica, adult oysters create a habitat with enough three-dimensional structure that vulnerable juveniles can avoid predation. The oyster, which once densely populated New York Harbor, has been absent for many years due to depleted oxygen levels caused by pollution. For the past five or so years, it appears to have been making a tentative reappearance in a few areas around the harbor, including on the pilings at The River Project. During this past summer, a total of three oysters were counted on the seventy-two terra cotta settling plates; two of the individuals were on the exposed surfaces of plates and grew to a length of about 25mm before dying. The remaining individual was in a protective crevice created between the plate and the frame holding it; future research may help elucidate what factors allow oysters to survive in the river.
Many species of fish long absent from the harbor, including those valuable to commercial and sport fishermen such as the sheepshead, Archosargus probatocephalus, are attracted to oyster beds. Oysters, and other filter feeders such as barnacles and mussels, are also capable of filtering large volumes of water; clearly, the ecology of the harbor in the future will be substantially affected by whether the materials used in its construction are conducive to settlement. Research may help in the choice and design of these materials; for example, the knowledge that larvae are attracted to concrete and have increased survivorship on surfaces with a texture that provides protection may help in the design of harbor structures that promote the development of healthy reefs.
Another interesting feature of current biodiversity in the river that the study may help clarify is the role that introduced species play in shaping subtidal communities. The lacy bryozoan Membranipora membranacea, which was first introduced to the east coast in the Gulf of Maine in 1987, and the golden star tunicate Botryllus schlosseri, which was introduced to Newfoundland from Europe, have both since spread all along the east coast of the United States, including to the pilings of Pier 26. Both of these species have been shown to have detrimental effects in other ecosystems such as the kelp beds of Nova Scotia and Monterey Bay, CA; the current research at the River Project may aid in determining what effect these non-native species will have on current and future biodiversity in the Hudson River.
posted by Stella Bella at 12:18 PM
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