Study Title: Design of a Monitoring Protocol/Plan for Environmentally Sound Management and

Development of Federal Offshore Borrow Areas Along the United States East and Gulf of

Mexico Coasts

Report Title: Development and Design of Biological and Physical Monitoring Protocols to

Evaluate the Long-term Impacts of Offshore Dredging Operations on the Marine Environment

Contract Number: 14-35-0001-31051

Sponsoring OCS Region: HeadquartersñInternational Activities and Marine Minerals Division

Applicable Planning Areas: East and Gulf of Mexico Coasts

Completion Date of Report: October 2001

Costs: FY 2000: Year 1 Effort Costs: $125,000 (Year 2 Effort due for completion in. 2002)

Project Manager: Jacqueline Michel, Ph.D.

Affiliation (Project Manager): Research Planning, Inc.

Address: 1121 Park Street, Columbia, South Carolina 29201

Principal Investigators: Jacqueline Michel, Rob Nairn, Jay Johnson, Dane Hardin

Key Words: sand resources, OCS, biological monitoring, physical monitoring

Background: The Minerals Management Service (MMS) International Activities and Marine

Minerals Division is charged with environmentally responsible management of Federal Outer

Continental Shelf (OCS) sand and gravel resources, that is, those resources lying seaward of the

State/Federal boundary. These resources must be managed on a long-term, large scale, systemwide basis to ensure that environmental damage will not occur as a result of continual and

prolonged use. Sand sources that are to be used repeatedly may require additional biological and

physical monitoring to ensure that adverse impacts to the marine and coastal environments do

not occur. Therefore, MMS funded this current study to develop biological and physical

monitoring templates for the Federal OCS sand resources.

Objectives: The project objectives were to: 1) Develop field monitoring systems to evaluate the

physical and biological impacts of using Federal offshore borrow areas on a long-term basis;

2) Examine the feasibility, appropriateness, and desirability of putting these monitoring systems

into place and identification of the need for collection of supplemental biological data or physical

modeling information in the Federal borrow areas; and 3) Identify the need for and collection of

any additional geological/geo-physical data to define available sand supplies for planned projects

within the study areas.

Description: This study consisted of a comprehensive literature review to clearly identify the

geophysical processes and biological ecosystems that would be affected by OCS sand mining for

beach nourishment and habitat protection. The first step was to develop a series of broad

scientific questions around which the monitoring program would be designed. Following the

completion of the literature review, the project team identified those ecological resources

(physical and biological) that would have the greatest potential for being affected by offshore

sand mining, both directly and indirectly. Impacts occurring from a one-time dredging event at a

given location or as repeated dredging of an area over some time period were included.

Direct physical impacts to seabed characteristics include removal and disturbance of the

substrate and exposure of an underlying layer with different characteristics (i.e., grain size,
reduced dissolved oxygen levels, and compaction), and changes in grain size of surficial

sediments due to settling of fines from overspill plumes or sediment reworking. Indirect

physical impacts include changes related to erosion and deposition. These changes will only be

significant where they result in biological impacts. Indirect impacts include changes to the

waves within and beyond the borrow area, changes to bed shear stresses and related seabed

mobility due to changes to waves, and changes to near bed current velocities driven by tides,

wind, and large-scale phenomenon. Based on the literature review, it was determined that, from

a purely physical perspective, the only change of consequence is the potential impact of dredging

on shoreline change. All other physical changes and impacts caused by dredging are important

only if they result in a biological impact, either directly or indirectly. Thus, four physical

monitoring and modeling protocols were developed to address these issues:

1. Bathymetric and Substrate Surveys

2. Sediment Sampling and Analysis

3. Wave Monitoring and Modeling

4. Shoreline Monitoring and Modeling

Table 1 is a summary of these four physical monitoring protocols.

For marine biota, the biological communities and associated habitats that were determined as

most likely affected by OCS sand dredging were soft substrate benthic communities; nekton; and

marine mammals and wildlife. Studies of the recovery of soft substrate benthic communities

following dredging have indicated that communities of comparable total abundance and diversity

can be expected to re-colonize dredge sites within several years. However, even though these recolonized communities may be similar in terms of total abundance and species diversity, their

taxonomic composition, in terms of dominant species and species abundance, is often very

different from pre- to post-dredging. The ecological utilization of ridge/shoal features by fish

species as critical habitat for spawning, overwintering, or foraging area is relatively unknown,

and should be addressed. However, the greatest potential effect to the fish community utilizing a

dredge borrow area is an alteration in trophic energy transfer from the benthos to the fish

population. For marine mammals and other marine wildlife such as sea turtles and birds, of the

identified direct and indirect impacts, the greatest potential for serious effect is associated with

direct collision with the dredge vessel or entrainment in the suction dredge. Thus, two biological

monitoring protocols were developed to address these issues:

1. Benthic communities and their trophic relationships to fish

2. Marine mammal and wildlife interactions during dredging

Table 2 is a summary of the biological monitoring protocols.

Costs for implementing the monitoring protocols were estimated for a hypothetical project site

off the coast of Maryland and Delaware. Year 1 costs for both physical and biological

monitoring programs ranged between $374,160 and $826,800. If the monitoring program was

required for a full seven years, total costs were estimated to range between $1,194,800 and

$3,429,000.
A key component of any long-term scientific study or monitoring program is the need to adapt

the original study design and approach to reflect information and understanding gained from ongoing studies during the execution of the program. Thus, it is recommended that the MMS

establish a permanent scientific review/advisory board to oversee the implementation and

evolution of the OCS sand monitoring program and advise the MMS on the program

components. Another key role of the scientific advisory board is to ensure the scientific validity

and integrity of the monitoring programs and their findings. Long-term monitoring programs

will create extremely large databases of information that must be properly organized and

documented with appropriate metadata. Therefore, data management guidelines are

recommended that will optimize use of the data for identifying potential long-term impacts and

support of decisionmaking.

The report identifies information gaps that will need to be addressed either prior to the

implementation of the monitoring program or concurrent with its implementation, including:

1. Identification of procedures to dredge shoal and ridge features that will minimize

ecological impacts and/or speed recovery

2. Gaps in baseline data, both biological and geomorphological, at OCS dredging sites

3. Determining the use and role of sand ridges and shoals as potential "essential fish habitat"

by migrating or resident fish

4. The potential for benthic biological differences that run longitudinally along the ridge and

shoal features that may affect the proposed sampling design and require further

stratification

5. Whether the relationship of carbon and nitrogen stable isotopes and trophic level improve

the scientific knowledge of how the alteration of organic matter and benthic invertebrate

communities affect the population of bottom feeding fish in an anthropogenically

disturbed and recovering area of the ocean

6. Identification of strategies to remove sand from a shoal/ridge feature to maximize their

use and maintain the integrity of the feature

Because bathymetric highs are the current focus as OCS borrow sites, the report includes a

summary of the characteristics of OCS shelf sand ridges and shoals. It is important to note that

in the future it is likely that the range of deposit types will be expanded to include paleochannels, paleo-deltas, and other buried sand deposits. It is has been postulated that while ridges

and shoals are more readily (and less costly) to identify in the first place, it is likely that more

economic (i.e., larger and closer to shore) and higher quality buried deposits will be discovered

within federal waters.

Study Products: Research Planning, Inc., Baird & Associates Ltd., and Applied Marine

Sciences, Inc., 2001. Development and Design of Biological and Physical Monitoring Protocols

to Evaluate the Long-term Impacts of Offshore Dredging Operations on the Marine

Environment. U.S. Department of the Interior, Minerals Management Service, International

Activities and Marine Minerals Division (INTERMAR), Herndon, VA. OCS Report MMS

2001-089, 116pp.