Deep-water Macroalgal and Seagrass Assemblages

Introduction

Unlike terrestrial plants, macroalgae, or limu, and other photosynthetic marine organisms are restricted in their distribution in the ocean by the amount of light available and the amount of light needed to carry out photosynthesis.  The region of the water column which supports photosynthetic life is called the photic zone.  Over 95% of the ocean's volume does not support photosynthesis.  Sunlight does not reach the bottom of the ocean because light is rapidly weakened by the scattering and absorption of water molecules and other suspended and dissolved particles.  In clear tropical waters, the photic zone may extend to 100 - 200 meters.  

Possible linkages between anthropogenic and natural nutrient fluxes inside and outside the macroalgal meadows will also be studied by collecting pore water.  An innovative sediment pore water sampler will be used with the submersible manipulator arm to collect pore water for nutrient analyses from soft sediments in and around these sites.

About HURL and OE

Established by the National Oceanic and Atmospheric Administration (NOAA) and the University of Hawaii, the Hawaii Undersea Research Laboratory (HURL) focuses on deep- water marine processes in the Pacific Ocean.  HURL's research program is built through an annual request for proposals, funded requests from private, state, or federal agencies and participation in international collaborative research projects in the Pacific. 

NOAA's office of Ocean Exploration (OE) supports a variety of endeavors that explore and increase our understanding of our oceans.  Key components that make up the NOAA Ocean Exploration Mission: mapping the physical, biological, chemical, and archaeological aspects of the ocean, understanding ocean dynamics at new levels to describe the complex interactions of the living ocean, developing new sensors and systems to regain U.S. leadership in ocean technology, and reaching out to the public to communicate how and why unlocking the secrets of the ocean is well worth the commitment of time and resources, and to benefit current and future generations.

This project is supported by grants provided by the National Undersea Research Program, HURL and NOAA's office of Ocean Exploration.

Cruise Information

September 2004 cruise will run from 2 September to 8 September.  Project scientists on-board: Dr. Celia Smith, Dr. Frank Sansone, Thomas Savauge, Brian Greene, Heather Spalding, and Kim Peyton.

December 2004 cruise will run from 12 December to 18 December.

Research

This project is a multidisciplinary effort exploring the temporal and spatial dynamics of deep-water macroalgal meadow ecology, macrofaunal associations and soft sediment nutrient chemistry.

Main Objectives:

• quantify deep-water macroalgal abundance and composition to determine biogeographic affinities, temporal and spatial variability, and the extent of invasion by alien species,
• survey macrofauna (fish and invertebrates) to determine if deep-water macroalgal meadows are being used as a habitat and/or food source,
• determine the nutrient dynamics of soft sediments, its role in deep-water algal growth, and the effect of psammophytic (sand-dwelling) algae on sediment chemistry, and
• calculate carbonate sand production rates for meadows of calicified algae (e.g., Halimeda incrassata).

The outcome will be an ecosystem-wide understanding of the role of deep-water macroalgae in the near-shore environment.

Educator at Sea

Teachers from Oahu and Maui are participating in the research cruises and their journals on both the natural and cultural resources associated with some of the deep-water passages in the Hawaiian archipelago will be made available.

Logs

Daily and/or weekly logs from the cruise will be made available.