Michael A. Poirrier

The MRGO Navigation Project: A Massive Human-Induced Environmental, Economic, and Storm Disaster

Abstract It is generally felt in the water resources community that the most significant twenty-first century public works projects will be those undertaken to correct environmental damage caused by twentieth century projects. A second axiom is that the switch from economic development to restoration and mitigation, what we call redemption, often will be precipitated by disaster. Finally, it must be expected that the repair project will cost far more than the initial public investment but also may have economic revitalization potential far exceeding anticipated environmental benefits. We examine this cycle for the federally funded Mississippi River Gulf Outlet (MRGO) navigation project east of New Orleans, beginning with its much heralded birth in 1963 as a 122 km long free-flowing tidal canal connecting New Orleans to the Gulf of Mexico and ending with its recent de-authorization and closure. We track the direct and indirect effects of the project through its commercial failure, and then on to the official denial, the pervasive environmental impacts, and finally exposure of its role in flooding New Orleans during Hurricane Betsy in 1965 and more seriously during Hurricane Katrina in 2005. Post de-authorization planning to curtail continuing environmental and economic damage now offers an opportunity to apply lessons that have been learned and to reinstate natural processes that were disrupted or interrupted by the MRGO during the half-century of its operation. One surprising outcome is that the restoration program may turn out to be more commercially successful than the original navigation project, which was conceived as an agent of economic transformation. The U.S. Army Core of Engineers still does not acknowledge, even in the face of compelling scientific evidence, that the MRGO project was a significant cause of early and catastrophic flooding of the Upper and Lower 9th Wards, St. Bernard Parish, and New Orleans East during Hurricane Katrina. A modeling effort that removed the MRGO from the landscape, and restored the cypress swamps and marshes killed by the MRGO, reduced flooding from Hurricane Katrina by 80%. We conclude that the MRGO spelled the difference between localized flooding, and the catastrophe that killed 1464 people and inflicted tens of billions of dollars of property damages. If the MRGO-caused economic damages associated with Hurricanes Betsy and Katrina are combined with those of construction, operation and maintenance, and wetlands destroyed, then the total economic cost of the MRGO is in the hundreds of billions of dollars.

A Discriminant Functions Analysis of Sunfish (Lepomis) Food Habits and Feeding Niche Segregation in the Lake Pontchartrain, Louisiana Estuary

Abstract The food habits of four species of sunfish, Lepomis macrochirus, L. microlophus, L. punctatus, and L. gulosus were studied in the Lake Pontchartrain estuary. Forty estuarine food items were identified from stomach samples. Although the food items were different from those of Lepomis spp. in fresh water, specific feeding patterns in regard to prey size and space partitioning were comparable. A discriminant functions analysis was used to objectively compare specific differences in stomach content data. Differences in discriminant function scores appeared to be due to interspecific feeding niche segregation.

Response of submersed aquatic vegetation (SAV) in Lake Pontchartrain, Louisiana to the 1997–2001 El Niño Southern Oscillation shifts

Lake Pontchartrain is a large, shallow, low salinity estuary north of New Orleans, Louisiana. It is a water quality impaired system with restoration efforts in progress. One restoration goal is the reestablishment of historic submersed aquatic vegetation (SAV;Vallisneria americana Michx. andRuppia maritima L.), which has been in a state of decline since first studied in 1953. Annual SAV surveys and monthly water quality monitoring were conducted at four to five sites from 1996 through 2003 to evaluate trends and determine the causes of SAV change. We found a rapid increase in the distribution and abundance ofR. maritima in 1999 that persisted through 2002. An El Niño Southern Oscillation shift occurred between 1997 and 2001, which produced a drought in southern Louisiana as an ancillary effect of La Niña. This study was conducted to investigate causal links between the El Niño to La Niña climate phase shift and SAV change. We found that salinity and water clarity increased during La Niña. Increased water clarity produced a rapid increase in the euryhaline speciesR. maritima in deeper water and at historic sites where SAV had not been found since 1953. As salinity increased, the freshwater speciesV. americana andMyriophyllum spicatum L. declined, andNajas guadalupensis (Spreng.) Magnus andPotamogeton perfoliatus L. disappeared. In 2003, after the La Niña phase, salinity and water clarity decreased,R. maritima decreased, and the freshwater species increased, butP. perfoliatus was still absent. We found that salinity controlled SAV species composition, and water clarity controlled SAV colonization depth (Zcol=2.3/Kd). Our study demonstrated that climatic shifts cause cyclic changes in Lake Pontchartrain SAV and that restoration could be accomplished by improving water clarity. Due to the sensitivity of SAV to environmental change, similar responses to short-term and long-term climate changes should occur in other estuarine systems.

The Barnacle, Balanus subalbidus, as a salinity bioindicator in the Oligohaline Estuarine Zone

The distribution and size of the barnacle Balanus subalbidus were studies along salinity gradients in coastal Louisiana and Mississippi. It was common in gradient estuaries occurring in salinities ranging from near fresh water to 16 ppt. It was the dominant barnacle species in the oligohaline zone, but at salinities above 6 ppt its relative abundance decreased and it was replaced by B. improvicus and B. eburneus. Its low-salinity limit corresponded to the boundary between the oligohaline and fresh water estuarine salinity zones and there was a high negative correlation between size (basal rostral-carinal diameter) and salinity. Its size and distribution could be used to determine prevailing salinity at a site because of its abundance and uniform distribution in oligohaline areas.

Effects of the 1997 Bonnet Carré Spillway Opening on Infaunal Macroinvertebrates in Lake Pontchartrain, Louisiana

Abstract The Bonnet Carré Spillway was constructed in 1931 to divert floodwater from the Mississippi River into Lake Pontchartrain, an oligohaline estuary near New Orleans, Louisiana. The spillway was opened from March 17 through April 18, 1997. Infaunal macroinvertebrate population, surface and bottom salinity, and dissolved oxygen data were examined to determine the effects of this diversion. These data were obtained from November 1996 through November 1998 from five sites on an east-to-west transect across Lake Pontchartrain. A community composed of oligohaline taxa persisted during the freshwater period, but changes in dominance, and to a lesser extent composition, occurred over time and among sites. There was a pronounced spatial effect related to the distance of the sites from the spillway and from tidal passes. Based on decreases in species diversity (H′), abundance, and the number of taxa, it appears that the opening had a deleterious impact on the benthos. The cause of these changes cannot be attributed with certainty to any one factor, but we speculate that they were the result of reduced salinity, cyanobacterial blooms, and hypoxia/anoxia. Although recovery occurred, based on overall changes in macroinvertebrate abundance and Rangia cuneata clam biomass, there was no evidence of increased benthic invertebrate productivity.

A continuous-flow system for growing fresh-water sponges in the laboratory

Two fresh-water sponge species, Ephydatia fluviatilis and Spongilla alba, were grown from gemmules in the laboratory. A system incorporating a continuous flow of filtered habitat water and live bacteria from a chemostat culture as a food source were used. Experiments with this system demonstrated a relationship between the concentration of bacteria and sponge growth rate. Because the continuous flow of water eliminates the effects of substances released by sponges and growth rate can be predicted for a given bacterial concentration, this system permits experimental studies which were not feasible in the past.

Effects of calcium and salinity on the growth rate of Ephydatia fluviatilis (Porifera: Spongillidae)

The freshwater sponge, Ephydatia fluviatilis (Porifera: Spongillidae), was maintained in a continuous-flow laboratory culture system under several conditions of calcium ion (Ca++) concentration and salinity. Experimental results suggest that sponge growth rate increases with increasing Ca++ concentration, that sponge growth rate decreases with increasing salinity, and that the negative effect of higher salinity can be overcome by increasing Ca++ concentration. The experimental results correlate well with field observations on the effects of salinity and Ca++ on the distribution of E. fluviatilis.

Water temperature: A factor in the seasonality of two freshwater sponge species, Ephydatia fluviatilis and Spongilla alba

Two freshwater sponge species, Ephvdatia fluviatilis and Spongilla alba, were maintained in a continuous-flow laboratory culture system at several different water temperatures. Experimental results suggest that sponge growth rate is affected by water temperature and that it is affected differently in the two species. The results correlate well with field observations on species abundance at different water temperatures and thereby support the view that water temperature is a factor determining seasonality in these species.

GROOMING BEHAVIOR AND ASSOCIATED STRUCTURES OF THE MYSID MYSIDOPSIS BAHIA

ABSTRACT Grooming behavior as an antifouling mechanism is documented for the first time in a mysid crustacean. Behavioral observations and a scanning electron microscope (SEM) survey of the setae reveal that Mysidopsis bahia uses specialized setae to remove fouling epizoites and particulates from vital areas of the body. Various combinations of appendages are used in different grooming activities. The mandibular palps are highly modified for brushing the antennae. The second thoracic endopod is the most active appendage functioning in grooming the antennae, setae of the marsupium, and other thoracic appendages. The third through eighth thoracic endopods are slender, flexible, and have long comblike setae that are used to clean the natatory exopods and other structures. Quantitative observations show that more grooming activity is focused on the antennules than on the antennae. Cleaning of the telson and outer marsupial walls was also observed. Although young mysids possess all appendages when released from the marsupium, the appendages of newly emerged M. bahia lack important setal types and numbers necessary for effective grooming. The juveniles appear to be dependent on ecdysis associated with growth to counter fouling. A comparison of fouling between adults and juveniles held in turbid water confirms the effectiveness of grooming behavior and associated structures.

Freshwater sponges (Porifera: Spongillidae) from Panamá

Aquatic habitats in the Republic of Panamá were examined for freshwater sponges during 21 Feb. to 6 March 1986. Eunapius carteri, Trochospongilla leidyi, and Trochospongilla horrida were found in the northern canal area. This is the first report of E. carteri and T. horrida from Central America, and the first record of E. carteri from the Western Hemisphere. Taxonomic characters used to distinguish T. leidyi and T. horrida from similar South American species are discussed.