Friday, September 23, 2016

BioBase EcoSound does Seagrass, Kelp, and Tides Too!

Although BioBase EcoSound was originally developed for aquatic vegetation mapping in inland lakes, users along both US Coasts have helped us diversify its toolbox to now be a powerful coastal habitat mapping tool as well!

One of the biggest challenges of mapping coastal habitats is their tidal influence with depths changing harmonically based on the moon phase and other factors.  Fortunately, however, widespread tide stations and large public databases of tide predictions allow for accurate and precise offsets to georeferenced and time-stamped sonar logs from Lowrance HDS or Elite units uploaded to BioBase EcoSound.  BioBase EcoSound immediately queries the nearest tide station to your upload (up to 75 km) and adjusts your depth and seagrass or kelp biovolume to the Mean Lower Low Water (MLLW) datum every 5 minutes.  Tidal statistics (Avg., start, stop, high, low,) are archived in your account for each trip.

Simulate Tidal Conditions with the Data Offset Tool
Figure 1. demonstrates what seagrass density conditions looked like in a harbor in Newport Bay CA USA on 12/5/2012 at MLLW (Data collected by Rick Ware; Coastal Resources Management Inc., Corona Del Mar, CA).  Areas of red indicate where seagrass or eelgrass (Zostera marina) grows to the surface at MLLW and may interfere with the passage of vessels in and out of the Marina.  Thus, these habitats may be high risk of damage.  Full access to the trip displayed in Figure 1 among other trips, is available for free to anyone in our public demo account

We can also simulate what this same area looks like under high water conditions (Mean Higher High Water - MHHW) using the data offset tool in BioBase (Figure 2).  MHHW data were retrieved from the interactive NOAA tide web tool and the average tide (1.5 ft) for the hour that data were collected in this area in Newport Bay was added to the MLLW average offset (3.84 ft; Figure 3).
Figure 1. Mapping tracks (red lines) overlain on a seagrass density heat map with depth contours.  Areas of red are where seagrass grows close to the surface at low tide (MLLW).  Areas of green are low-lying seagrass areas.  The cross section of the sonar log displaying the high resolution imagery of StructureScan is displayed on the right and synchronized with the map upon each upload (Trip Replay). Data were collected with Lowrance HDS and uploaded to BioBase
Figure 2.  Data Offset tool in BioBase EcoSound can be used to offset depths to a benchmark elevation (e.g., full pool for reservoirs), or custom tides as is the case here.  MHHW data were retrieved from the Newport Bay Entrance Tide Station and added to the MLLW offset to simulate high tide conditions

Figure 3.  Trip-specific tide data retrieved  from the NOAA Tidal Prediction web page.  60-min values during the precise hour of data collection were added to the MLLW offset in the Data Offset tool in BioBase EcoSound.
Compare effects of tides in the automated reports
Comparing results from the automated reports (Figures 4 and 5) one can see the effect that tides can have on biovolume and potentially seagrass habitat conservation.  Notice that percent vegetation cover (PAC) does not change much with tides, but biovolume (BVp), which brings in the 3rd dimension of plant height, does.

Figure 4.  Excerpt of automated report for MLLW conditions in Newport Bay.  Statistics on survey area, water volume, vegetation summary statistics, waypoint summaries, and important metadata are available with each upload.
Figure 5. Excerpt from BioBase EcoSound trip report with a MHHW offset added to the output.  PAC (grid).  Compared with  MLLW data in Figure 4, PAC only increased from 64.5% to 71.3% but average biovolume in vegetated areas decreased from 38.8% at MLLW to 16.7% at MHHW. 
Interpreting outputs in extreme tides
In some areas of the Pacific Northwest it is not uncommon to see 10 ft tides.  Mapping seagrass at high tide in areas high and dry at low tide, represents a great opportunity to passively map the cover and density of seagrass beds. In areas exposed at low tide, BioBase Ecosound will reclassify any seagrass detected to 100% biovolume, displaying a red area of seagrass coverage (Figure 6).

Figure 6A.  Map displaying density of seagrass beds at MLLW in Puget Sound, WA USA with a 9.3 foot average tide.  200 khz Sonar chart on right shows the actual depth during the time of assessment and seagrass growth on bottom.
Figure 6B. Zoom of Figure 6A and display of tide-corrected point data along boat track (red line).  Highlighted cell corresponds to the orange dot on the map on the left and the area just to the right of the faint white line on the sonar graph on the right.  If the seagrass plant height is greater than the tide-corrected depth, the bv registers a n/a and it is considered 100% (red) in the biovolume map.  If plant height is less than the corrected-depth, biovolume is recalculated as the proportion of plant height to corrected water depth. Zero plant height and biovolume areas remain

Use the Polygon Tool to delineate and monitor sensitive seagrass areas.
Figure 7 demonstrates how a polygon could be drawn and used to calculate seagrass cover statistics in a specific area and time.  You can use the same polygon on subsequent trips to monitor change over time and evaluate protection or restoration.

Figure 7.  The Polygon Tool was used to draw a boundary around a bed of seagrass in a shallow area of Puget Sound, WA USA where boat traffic is high.  The same polygon can be used to monitor change across multiple trips in the same area (users should take reasonable measures to travel the same path repeatably to generate the most comparable results)

Automated Tools for Kelp Detection and Mapping
Kelp, a widespread marine macroalgae is also the focus of global conservation efforts.  Kelp can grow to be very tall and provide habitat for a variety of nearshore marine life.  We have seen great success by researchers like Rick Ware from Coastal Resources Management Inc using Lowrance HDS and BioBase EcoSound to map kelp forests of the US Pacific Coast (Figure 8).  As seen in the Broadband 200 kHz sonar log on the right, EcoSound detected Kelp up to 9.8 m (32 ft) long!  Ground truth data collected by Mr. Ware confirmed this acoustic signal was indeed kelp.  This trip is also publicly available in our demo account.
Kelp, BioBase, mapping, Lowrance
Figure 6.  Kelp beds off the Southern California Coast detected by Lowrance HDS and BioBase EcoSound and confirmed by researchers.
Let us know how you are using BioBase to address questions in tidal influenced habitats.

Monday, September 19, 2016

Portability Options for Your Lowrance

We recently sent out a mailer to our subscribers letting them know about the portability solutions that we have come up with.  Within minutes we received photos and details from many of our customers about how some they have used a little ingenuity to mount their Lowrance units on unique water craft.  Below we have a photo gallery of images that could help you design your own portable setup.  Of primary importance, however, is a mount that minimizes cavitation (air bubbles) directly under the transducer (e.g., surface noise) and maintaining a correct angle on the transducer.  See recent blogs on this topic. The preferable solution is to permanently mount separate transducers following DIY guidance like shown here on each survey craft and just move the Lowrance Elite or HDS display from boat to boat.  But if the job calls for a fully portable mount, we can help!

Coastal SeaGrass  Mapping


Rick Ware, Senior Marine Biologist with Coastal Resources Management, Inc. sent us these images of his set up for portability on their Achilles inflatable.  He commented that the same system can be used on his single and double kayaks as well.

Creative Low-cost Kayak Set-ups


When the waterbody you plan to map calls for a small craft a kayak works great.  The external mount for the transducers works and is preferable to shooting through the hull, however, drag and surface growing vegetation can cause issues.  The ideal mount is described here by Lowrance's Lucas Steward on a stand-up kayak with a scupper hole and Lowrance's scupper-hole transducer mount (part no. 000-10606-001).  Here's a couple of shots (top/bottom) of the scupper-hole set up and pond data collections with a Lowrance Elite 5 or 7 Ti


Or, you can buy a battery and mounting kit like shown here



A low-budget kit using a toolbox to house a 9 ah lead acid sealed battery which will run an Elite-Ti all day, maybe multiple.  Elite-7Ti is mounted onto the top of the tool box. The t-channel and strap hooks are only things screwed to the kayak and are above the water line (no need for silicone).  This kayak is used each day for watersport rentals so quick and easy on and off was important (Photos courtesy of John Paulson, City of Hutchinson MN, USA).

Florida Air Boat



Dean Jones, with the Center for Invasive and Aquatic Plants sent us these images of his portable set up on the back of an air boat.  Since the early goings of vegetation mapping with EcoSound we've worked hard to find and test a good mount for an airboat.  Dean has found a great solution that works every time!  He's getting great maps

Although the Lowrance units are always easy to install sometimes our users need a little creativity to meet their unique requirements.  Necessity is the mother of invention . . .

Thru-Hull and Narrow Beam Third Party Options

Ryan Moore also with the Center for Invasive and Aquatic Plants was looking for narrow beam options for more precise mapping of aquatic plants and installed an Airmar B164 bolt-thru-hull transducer.


Navico's full line of compatible transducers can be browsed and purchased at the Navico Store.

Below is a gallery of photos you may find helpful for setting up your Lowrance unit and accessories

Creative set up from guts of an old trolling motor (try Craigslist.com), a $20 machined aluminum cap, and $3 in hardware. Photos courtesy of Michael Dorland.
From our German distributor Echolotzentrum Schlageter.  They also make a professional heavy-duty dual mount for your skimmer + LSS2 transducer.

Spring-back bracket from Transducer Shield and Bracket http://www.transducershieldandsaver.com/product/sbb-4-spring-back-bracket/.  Photos courtesy of Josh Bowen at Duke Energy Carolinas.

Lowrance HDS, portable, transducer, skimmer, LSS-2

Lowrance HDS, portable, transducer, mount

Portable Lowrance HDS7 Touch Set up on a 14-ft Carolina Skiff (Photo Courtesy of Aquatic Systems Inc)

Photo courtesy of Bruce Sabol, Army Corps of Engineers Research and Development Center.  In this example, high speed may cause excessive surface noise on your Sonar screen.  Slow speed or adjust transducer placement if this is an issue.



Lowrance HDS, portable, bracket, GPS, external, mount


Photo courtesy of Bruce Sabol, Army Corps of Engineers Research and Development Center


Lowrance HDS, NMEA, GPS, installation
Photo courtesy of Bruce Sabol, Army Corps of Engineers Research and Development Center

Lowrance HDS, NMEA, GPS, installation

The NMEA2000 protocol is a great innovation to network a range of accessory devices, but adhering to installation instructions is important or your HDS or Elite Ti unit will not find the device.  In addition to the diagrams and shots above, Lowrance's Jacob Scott provides a very instructional video. Always verify that the GPS signal is being received by the antenna before proceeding to map lakes (check System-Satellites-Configure - look for the name of the internal antenna - e.g., Point-1 - to be displayed and active).  External GPS directly over the transducer is important for creating the most precise map output.


Although it eliminates portable options. the mount that ensures consistent, strong, and correct signal is a permanent mount and ideally, installed professionally by your local marine dealer or service center.
Hydraulic tilt professionally installed.  Good for stowing.  Photo courtesy of Amy Peters; South Florida Water Management District

Another creative kayak installation; photo courtesy of Dr. Reed Green; Adjunct Professor University of Arkansas Little Rock.
Lowrance StructureScan Kayak ciBioBase
StructureScan mount on a kayak.  Photo courtesy of Dr. Reed Green Adjunct Professor University of Arkansas Little Rock.
Lowrance skimmer transducer mount through a scupper hole in a kayak.  Photo courtesy of Dr. Reed Green Adjunct Professor University of Arkansas Little Rock.




UPI Michigan's unique portable solution!


Rig up a fixed but swinging arm that carries the benefits of locking the transducer into the correct position when in use, but allowing the user to stow when needed.


From our Finnish Service Manager, Petteri Partenen: "This mount was made for a portable structure scan solution. [Simrad] NSS12 was in a pelicase with batteries, LSS HD and WIFI-1. On the pics it was on test on a Navy tender. GS15 GPS antenna was mounted on top of the mount to have an accurate position at the transducer location."

For more information about any of the solutions shown above, contact us at info.biobase@c-map.com