Action, Monitoring, and ResearchAction, Monitoring, and Research

his assessment of the causes and consequences of Gulf of

Mexico hypoxia, and its analysis of options for dealing with it,

is drawn from the assembly and peer review of a massive

amount of direct and indirect evidence collected and reported

over many years of scientific inquiry. The findings presented are

thus well founded and are grounded in those research and moni-

toring results. There are, however, always uncertainties in scien-

tific analysis. This section identifies areas of further monitoring

and research that are needed to reduce those uncertainties in

future assessments and to aid decision making in an adaptive man-

agement framework.

The complex nature of nutrient cycling and transport withinthe MARB and Gulf of Mexico make it difficult to predict specificimprovements in water quality that will occur for a given reduc-tion in nutrient inputs. Nutrient cycling is affected by atmos-pheric, watershed, riverine, and marine processes. Many of theseprocesses, such as nitrogen transformations in river reaches, arenot fully understood at the local scale at which they occur. Large-scale, multidisciplinary interpretations that integrate knowledgeacross these hydrologic compartments are difficult.

Further, it is clear that environmental responses to managementactions in the MARB likely will be slow, possibly requiringdecades of data to demonstrate statistically that remedial actionshave helped the recovery of oxygen concentrations in the Gulfand have improved water quality in the Basin. For example, thenitrogen balance in the soil zone and ground water will adjust rel-atively slowly to changes in nitrogen inputs and outputs, slowingany change in the flux of nitrogen to the Gulf. At the same time,the flux of nutrients to the Gulf most likely will respond quicklyand dramatically to large variations in precipitation and runoff—further complicating measurement of reductions in nutrient flux.

A comprehensive program of monitoring, interpretation, mod-eling, and research to facilitate continual improvement in scientificknowledge and adjustments in management practices should becoupled to whatever initial nutrient management strategies arechosen (see Figure 6.1). This adaptive management schemeinvolves continual feedback between interpretation of new infor-mation and improved management actions.

Chapter 6 : Adapt ive Management � 47

Monitoring and Research in aModeling Framework

The adaptive management frameworkincludes monitoring programs that useintegrated models of the hydrologic andecological systems for interpretation ofsystem change. Whole-system monitoringwill enable comprehensive interpretationof processes and linkages that affect nutri-ent concentrations and transport withinthe MARB and development of hypoxia inthe Gulf. These coordinated monitoringefforts must be able to:

� detect environmental trends to evaluatethe effectiveness of managementactions, to enable effective adaptationof strategies over time;

� observe physical, chemical, and biolog-ical processes and their roles in thecause-and-effect relationships betweennutrient inputs and resulting environ-mental quality; and

� differentiate among trends caused bychanges in climate, streamflow, nutri-ent and landscape management meas-ures, and other concurrent factors.

An effective research strategy is alsointegral to the adaptive managementframework. Coordinated research effortsimprove monitoring designs, support the

interpretation of mon-itoring output, and

increase the predictivepower of models and other

assessment tools used in themanagement process.

For a system as largeand complex as the

MARB and thenorthern Gulf of

Mexico, moni-toring andresearch should

be integrated usingholistic models that simulateour understanding of howthe overall system functionsand how management prac-

tices can best be implemented. Suchholistic models include a suite of concep-tual, functional, and numerical formula-tions; integrate research findings; and aretied to monitoring programs designed to

both provide input variables and verifymodel outputs. River monitoring datashould be integrated with offshore eco-logical and oceanographic data on appro-priate time scales. An effective modelingframework would include models thatsimulate:

� transport and transformation of nutri-ents (nitrogen, phosphorus, and silica)from natural, urban, and agriculturallandscapes to ground water and surfacewaters;

� inputs and outputs of nutrient flowthroughout the landscape to improveestimates of nutrient mass balances;

� biogeochemical cycling and waterquality effects of those nutrients onriver ecosystems within the drainagebasin;

� oceanographic and climate influenceson those nutrients and their impacts onGulf productivity as they leave theMississippi–Atchafalaya River system;

� impacts of increased nutrient flux onproductivity in the northern Gulf ofMexico ecosystem, including commer-cially and recreationally important fish-eries; and

� three-dimensional coupling of biologi-cal and physical processes in the Gulfecosystem influenced by theMississippi River discharge.

Within this larger modeling frame-work, important research and monitoringneeds have emerged from this assessment.Monitoring gaps are found in environ-mental programs of the MARB and Gulf,as well as in programs that monitor man-agement measures. Research needs includeimproving the quantitative understandingof the biogeochemical cycling of nutrientswithin the watershed and the Gulf and itsrelationship to the dynamics of organiccarbon flux in the Gulf; the roles of long-term change in climate, hydrology, andpopulation in year-to-year and long-termtrends in nutrient loads and hypoxia; andthe social and economic impacts of vari-ous management and policy alternativestrategies.

48 � HYPOXIA IN THE NORTHERN GULF OF MEXICO

A comprehensiveprogram ofmonitoring,interpretation,modeling, andresearch should becoupled to whatever initial nutrient management strategies are chosen

Chapter 6 : Adapt ive Management � 49

Monitoring Needs

A comprehensive monitoringprogram requires both measure-ment of environmental responsein the MARB and the Gulf ofMexico and tracking indicators ofprogrammatic progress towardmitigating excessive nutrients.

Environmental Responses in the Gulf

Essential components of anenvironmental monitoring pro-gram in the Gulf of Mexicoinclude efforts to:

� Document the temporal andspatial extent of shelf hypoxia,and to collect basic hydro-graphic, chemical, and biolog-ical data related to thedevelopment and maintenanceof hypoxia over seasonal

cycles. A triad of mid-summershelf-wide hypoxia surveys,monthly transects off Terre-bone Bay, and instrumentedarrays at stations in the coreof the hypoxic zone wouldprovide an optimal combina-tion of spatial and temporalscales of measurement andwould be consistent with theexisting long-term data.Establishing multiple verticaland horizontal instrumentarrays oriented cross-shelf andalong-shelf will better defineprocesses that control thetemporal and spatial develop-ment of hypoxia.

� Improve the collection of eco-logical, production, and eco-nomic information related tofishery and nonfishery species.

� Facilitate synthesis and inter-pretation of these data throughan integrated database.

Environmental Responses in the MARB

Essential components of anenvironmental monitoring programin the MARB include efforts to:

� Document the flux of nutrients,carbon, and selected otherwater quality constituents fromthe MARB to the Gulf ofMexico systematically on atleast a monthly basis and morefrequently at high flows—atleast 25–30 times annually.Additional monitoring sites inthe main channel of theMississippi River are needed toevaluate the extent of nutrientretention/loss within the lock-and-dam system, and to clarify

The adaptive management concept connects monitoring, analysis, and management actions with continuous feedback forimprovement. New understandings from research should be interwoven throughout the process.

Conduct research

Moni tMoni torsystemresponse

ImplementImplementmanagementmanagement

s t ra tegy

Interpret data ,analyze and

improimprove modele model

Improve modelpredict ion and

management planmanagement plan

Adapt ive Management FrameworkFIG. 6. 1F IG. 6. 1

Source: Herb Buxton, U.S. Geological Survey

50 � HYPOXIA IN THE NORTHERN GULF OF MEXICO

the extent of nutrient retentionin the lower Mississippi. Thereis a need to re-establish moni-toring of nutrients, carbon, andselected other water qualityconstituents in the major sub-basins (the 42 interior basins)throughout the MARB and toestablish monitoring in select-ed small basins within some ofthe 42 interior basins wherethe effects of changes in landmanagement practices onnutrient concentrations andyields will be easiest to detectand quantify.

� Monitor nutrients from atmos-pheric wet deposition in theMARB, and expand the currentlimited monitoring of nutrientsin atmospheric dry deposition.This information is needed todetermine if nutrient manage-ment strategies affect precipita-tion chemistry.

� Establish a periodic inventoryof effluent reporting conductedthrough the National PollutionDischarge Elimination System(NPDES) to systematicallyimprove current estimates ofnitrogen and phosphorus loadsdischarged to streams frommunicipal and industrial pointsources.

� Improve measurements for soilnitrogen and nitrogen loss.

Programmatic Measures Ongoing programs are taking

action to improve water qualityconditions within the MARB andGulf of Mexico. Coordination ofcurrent and future programs toimprove water and ecologicalconditions can increase their over-all effectiveness in achievinggoals. Some major measures ofprogress of ongoing programsinclude inventories of:

� changing patterns in othernutrient inputs to the Basin,such as fertilizer use and

manure application and dis-posal;

� acres of land leased annuallythrough the ConservationReserve Program and theConservation ReserveEnhancement Program;

� acres of created or restoredwetlands implemented throughthe Wetlands Reserve Program,the Emergency WetlandsReserve Program, the CleanWater Act section 319 pro-gram, and the various environ-mental restoration and relatedauthorities, such as the CoastalWetlands Planning, Protectionand Restoration Act, the Envi-ronmental Management Pro-gram and other Corps ofEngineers programs, and thePartners for Wildlife Program;

� acres of riparian buffers imple-mented through the Conserva-tion Buffer Initiative and theClean Water Act section 319program; and

� actions to reduce nutrientrunoff stimulated by theEnvironmental QualityIncentive Program and theClean Water Act section 319program.

Research Needs

The research needs outlinedbelow fall into two categories: (1) immediate priorities that areessential for designing near-termmanagement actions, and (2)longer-term priorities that fill crit-ical gaps in understanding as wellas guide efforts to mitigate andcontrol the effects of hypoxia andexcess nutrients.

Immediate Research PrioritiesEcological Effects of Hypoxia. A bet-ter definition of the past, current,and potential impacts of hypoxiaon both commercially and eco-logically important species andecosystems is needed. New retro-

spective analyses over longer tem-poral and spatial scales, based ondata from marine sediment coresshould improve the historical per-spective. Better understanding ofother factors that affect the eco-logical health and fisheries of thenorthern Gulf of Mexico is neededto uniquely identify the role ofhypoxia and to design effectivemanagement actions.

Contemporary effects. Additionaldata sources have yet to be exam-ined exhaustively, most notablythe SEAMAP database, whichincludes long-term fishery-inde-pendent data on nektonic species’composition in the northern Gulfof Mexico ecosystem. Modelanalyses of trophic structure andecosystem dynamics—which willhelp identify affected fisheryresources, and assess potentialfuture impacts—are also needed.

Historical perspective. Thenorthern Gulf of Mexico ecosys-tem may have already undergonesignificant ecological changeprior to initiation of the first in-depth scientific investigation inthe mid-1980s. Thus, the systemis likely in a transitional state asnutrient loading approaches newplateaus. Further research andassessment of these longer-termtrends are needed. New retro-spective analysis over longertemporal and spatial scales, basedon data from marine sedimentcores should improve the histori-cal perspective.

Watershed Nutrient Dynamics.There is a need to better under-stand the dynamics and timing ofmovement of nitrogen and othernutrients from the edge of thefield in agricultural landscapes tosmall streams and tributaries.Additional information is alsoneeded on the geographic distri-bution and design criteria for tar-geting wetland creation andrestoration efforts and to deter-mine if other strategies (e.g.,riparian buffers) and mixturesprovide the best nitrate reductionfor the least cost.

Chapter 6 : Adapt ive Management � 51

From edge of the field to streams.There is a need to better under-stand the dynamics and timing ofmovement of nitrogen and othernutrients from the edge of thefield in agricultural landscapes tosmall streams and tributaries. Thisis especially true as it relates totile drains and other practices thatmove nitrogen and other plantnutrients through the soildrainage system.

Wetlands creation. Additionalinformation is needed on the geo-graphic distribution and designcriteria for targeting wetland cre-ation and restoration efforts.There is also a need to determinewhich other strategies (e.g., ripar-ian buffers) and mixtures providethe best nitrate reduction for theleast cost. It is important tounderstand and quantify thepotential for changes in the pro-duction of the greenhouse gas

N2O that could occur from wet-land creation and restorationefforts.

Agricultural Practices. While im-provements in agricultural prac-tices have been achieved in recentyears and the efficiency of nitro-gen use has increased substan-tially, there is a need to betterquantify the effects of on-farmpractices and methods that inter-cept agricultural nutrients betweenthe field and ground water andadjacent streams.

Watershed/farm-scale studies.There is a critical need to scale upfrom experimental plots to water-shed/farm-scale studies falling intotwo classes. The first class includesstudies to better quantify anddemonstrate the effects of on-farmpractices, such as precision farm-ing, altered lateral spacing ofdrainage tiles, controlled water

table levels, use of fall and wintercover crops, altered timing of fer-tilizer application, and exploringalternatives to traditional croprotations. The second classincludes studies on better meansto intercept agricultural nutrientsbetween the field and groundwater and adjacent streamsthrough riparian buffers, wetlands,and other means.

Experimental policies and prac-tices. Measuring and quantifyingthe effectiveness of recent poli-cies and voluntary actions toreduce nutrient inputs should becoordinated on a basin scale.There is a need to better quantifyand understand the impacts ofcurrent and proposed policies(e.g., nutrient trading, fertilizer-use insurance) that increaseincentives to reduce nitrogen loss.Additionally, there is a need toevaluate how future policies or

Longer-Term Research Priorities

Nutrient Cycling and Carbon Dynamics– Soil organic nitrogen– In-stream, in-river, and Gulf sediment

denitrification– Nutrient cycling in the northern Gulf of

Mexico– Atmospheric deposition

Long-Term Changes in Hydrology, Climate, and Population

– Large-scale climate effects– Flood events– Mississippi–Atchafalaya River delta

management and restoration– Point-source and urban nonpoint-source

controls

Economic and Social Impacts– Economic values of river and lake water

quality improvements– Economic values of Gulf water quality

improvements– Economic trade-offs in agricultural systems

Immediate Research Priorities

Ecological Effects of Hypoxia– Contemporary effects– Historical perspective

Watershed Nutrient Dynamics– From “edge-of-field” to

streams– Wetlands creation

Agricultural Practices– Watershed/farm-scale

studies– Experimental policies and

practices

Research Priorities

RA

LPH

LA

UR

ER

52 � HYPOXIA IN THE NORTHERN GULF OF MEXICO

practices might best be imple-mented and administered undervarious institutional frameworks.

Longer-Term Research PrioritiesNutrient Cycling and CarbonDynamics. Research is needed toimprove understanding of nutri-ent cycling and carbon dynamics,particularly variations across theBasin and the relationship of site-specific actions to Basin-scaleeffects.

Soil organic nitrogen. Scientificinvestigations indicate that thesoil zone is a huge storage reser-voir of nitrogen. Both inputs toand outputs from this reservoirhave increased dramatically inrecent decades. Research isneeded to better understand min-eralization and immobilizationprocesses, to develop better

means to measure the amount andforms of nitrogen in the soil reser-voir, and to develop strategies tominimize leaching of nitrate fromthe soils to the streams.

In-stream, in-river, and Gulf sedi-ment denitrification. There is a needto better quantify denitrificationand nutrient retention rates insmall and large streams and inGulf sediments, and to comparethese rates to those achieved inriparian buffers and wetlands.

Nutrient cycling in the northernGulf of Mexico. Further refinementsof the relationships among nutrientfluxes, nutrient ratios, and nutrientcycling on the continental shelf inthe Gulf are necessary. Such refine-ments would improve simulationsof subsequent effects on primaryproductivity, species composition,development of hypoxia, and

higher trophic-level productivity inthe Gulf ecosystem.

Atmospheric deposition. Addi-tional research on atmosphericdeposition of nitrogen in theGulf is needed to improve under-standing of various cycling mech-anisms involving different formsof nitrogen.

Long-Term Changes in Hydrology,Climate, and Population. Additionalresearch is needed to more clearlyidentify, understand, and predictthe effects of long-term changes inhydrology, climate, and population.

Large-scale climate effects. Therelationship between large-scaleclimate patterns (e.g., long-termtrends and changes in variabilityof precipitation) and their poten-tial impacts on river flows, nutri-ent flux, and flow dynamics onthe continental shelf need furtherevaluation. Changes in precipita-tion, temperature, and flow pat-terns may have significantlong-term influence on the rateand pattern of nitrate flux withinthe basin, and on the physicalconstraints of nitrate assimilationin the northern Gulf. The poten-tial effects of future global climatechange on such large-scale cli-mate patterns should also be takeninto consideration.

Flood events. Episodic events,such as the Great MississippiRiver Flood of 1993 not onlyhave caused significant damage tolife and property, but also havetransported abnormally highquantities of nitrogen and phos-phorus to the Gulf. Studies areneeded to evaluate the potentialrole of flood prevention and con-trol methods that seek to distrib-ute and retain more floodwaterwithin the Basin and thus increasenitrogen retention, while protect-ing against flood damage.

Mississippi–Atchafalaya Riverdelta management and restoration.Studies are needed to improveunderstanding of nutrient cyclingin the deltaic plain in order toguide possible changes in man-agement activities, such as the

Scientists deploy conductivity, temperature, and depth (CTD) instruments, alongwith dissolved oxygen sensors, to sample water conditions in the Gulf.

Chapter 6 : Adapt ive Management � 53

diversion of floodwaters to deltabackwaters and coastal wetlandrestoration.

Point-source and urban nonpoint-source controls. The cost of nitro-gen reduction from point sourcesand from urban nonpoint sourceshas been analyzed on the basis ofexisting technologies and humanpopulation densities. The poten-tial for additional population andlandscape changes to offsetreductions achieved in nitrogenloading from the Basin should becarefully evaluated.

Economic and Social Impacts. In thespirit of a “win-win” approach toaction plan design and implemen-tation, all potential ancillarysocial and economic benefits ofmanagement actions as well as

potential adverse effects shouldbe identified and considered inthe design of monitoring andresearch activities.

Economic values of river and lakewater-quality improvements. Thebenefits of reducing nutrient loadsin the freshwater system are con-sidered significant. A great deal ofresearch into these benefits hasbeen conducted. Most studies,however, have been site-specificand have been performed forselected watersheds or water uses.There is a growing need for anaggregated analysis of both direct(e.g., drinking-water protection)and indirect (increased recreation)improvements in water quality, forthe Basin as a whole.

Economic values of Gulf waterquality improvements. To date only

the potential direct economiceffects of Gulf hypoxia on com-mercial fish catch have beenattempted. Additional workneeds to be done to explore abroader range of ecologicalimpacts, including potentialimpacts to biodiversity and tononmarket-valued ecosystemgoods and services.

Economic trade-offs in agricul-tural systems. Better estimates ofcost savings to agricultural pro-ducers from reduced fertilizernutrient inputs are needed.Similarly, better estimates of thesocial costs that could result fromnitrogen management or reduc-tion strategies (e.g., from disloca-tion in land use, agribusinessinfrastructure, and farm commu-nities) are needed.