Marine scientists use specialized tools to gather information about the ocean and its diverse inhabitants. Observing marine environments is fundamental to understanding Earth’s climate systems, ecological processes, and the health of marine ecosystems. These instruments allow researchers to explore everything from microscopic plankton to ocean currents and the seafloor.
Measuring Water Properties and Chemistry
Understanding seawater’s physical and chemical characteristics is foundational for marine science. Scientists use Conductivity, Temperature, Depth (CTD) profilers to measure these properties as they lower through the water column. A CTD provides continuous readings of salinity (derived from conductivity), temperature, and pressure (depth), offering a detailed water profile.
Niskin bottles, deployed on a rosette frame alongside a CTD, collect water samples at specific depths for chemical analysis. These bottles close at precise depths, securing a water sample. Current meters, such as Acoustic Doppler Current Profilers (ADCPs), use sound waves to measure the speed and direction of ocean currents at various depths. Other chemical sensors measure dissolved oxygen levels, pH, and nutrient concentrations, indicating water quality and biological productivity.
Acoustic and Visual Exploration Technologies
Marine scientists use technologies that “see” through water with sound or light to explore the underwater world. Sonar systems, including single-beam and multibeam echo sounders, map the seafloor by emitting sound pulses and measuring echo return times. This generates detailed topographic maps of the ocean bottom, revealing features like underwater mountains and trenches. Side-scan sonar provides detailed images of the seafloor surface by emitting fan-shaped sound beams to the sides.
Underwater cameras are deployed on various platforms to capture visual data of marine habitats and organisms. These cameras are often equipped with specialized lights to illuminate the deep-sea environment, where sunlight does not penetrate. Visual data complements acoustic surveys by providing direct observations of seafloor geology and its living communities.
Advanced Platforms for Data Collection
Vehicles and systems carry instruments into ocean environments for comprehensive data collection. Remotely Operated Vehicles (ROVs) are tethered underwater robots controlled from a surface vessel, allowing precise maneuvering and object manipulation in the deep sea. ROVs often carry cameras, lights, and sampling arms, enabling close-up inspection and collection. Autonomous Underwater Vehicles (AUVs) are untethered robots programmed to conduct missions independently, covering vast areas for extended periods. AUVs are equipped with various sensors for mapping, imaging, and measuring water properties.
Gliders are a type of AUV designed for long-duration missions, profiling the water column by changing buoyancy and using wings for movement. Manned submersibles allow scientists to directly observe and interact with the deep-sea environment. Uncrewed Surface Vehicles (USVs) operate on the ocean surface, collecting atmospheric and oceanographic data, or acting as communication relays for underwater vehicles. Research vessels serve as the primary base for deploying and recovering these platforms and instruments, providing laboratory space, and supporting expeditions.
Instruments for Studying Marine Life
Specialized tools observe, sample, and track marine organisms. Towed nets, such as plankton nets, collect microscopic plankton, while larger trawl nets sample fish and other nekton. For studying seafloor organisms, grab samplers collect surface sediment, and corers extract sediment cylinders, preserving their layered structure.
To track marine animals, scientists attach acoustic tags that emit sound signals or satellite tags that transmit data when animals surface. Underwater hydrophones listen for marine sounds, including whale vocalizations or the sounds of snapping shrimp. Environmental DNA (eDNA) sampling analyzes trace DNA in water samples, providing a non-invasive method to detect species presence. Specialized underwater microscopes observe living plankton in their natural environment.
Observing from Space
Satellites provide a broad perspective on the ocean surface, offering data on large-scale phenomena. Satellite altimetry measures the precise height of the sea surface, which scientists use to track sea level changes, ocean currents, and large eddies. Ocean color sensors detect variations in the color of the ocean, which relate to phytoplankton concentration and other suspended materials, indicating water quality and biological productivity.
Satellites also measure sea surface temperature, revealing patterns related to climate change and ocean circulation. Synthetic Aperture Radar (SAR) systems provide images of the ocean surface roughness, which can indicate wind speed, wave patterns, and even the presence of oil spills. These space-based observations complement in-situ measurements by providing continuous, global coverage of the ocean’s surface features.