Coastal Rivers Conservation Trust is seeking volunteers for a long-standing community science program that collects data on horseshoe crab populations in the Damariscotta River estuary. Horseshoe crabs will soon be arriving at the shores of estuary to lay their eggs.

A volunteer training session will be from 3-5 p.m. next Friday, April 18, in the Denny Conservation and Education Center at Coastal Rivers’ Round Top Farm in Damariscotta. Participants should bring tall rubber boots suitable for wading, but all other equipment is provided. It is important that volunteers be able to navigate a rocky shoreline and steep banks.

Registration is required and can be done online at coastalrivers.org/events.

Led by Director of Education and Community Science Sarah Gladu, the training will provide volunteers with some background on horseshoe crab biology and details on the monitoring procedure. The group will travel to a nearby monitoring site for some hands-on practice with procedure and documentation.

At the training, Gladu will share a schedule so volunteers can register for the times that suit their schedules. The schedule will vary according to the time of the daytime high tide. Volunteers do not need to be available to monitor every day.

These creatures are actually not crabs at all but are more closely related to arachnids — and they have existed in a similar form for over 250 million years. Coastal Rivers’ monitoring program is the sole source of data on horseshoe crab populations in the region. From the beginning of May through mid-June, volunteers spend approximately one hour during high tide each day counting horseshoe crabs. The process requires one volunteer in the water at the shoreline to spot and count, while a second volunteer on shore records the information on a clipboard. Volunteers also measure and record the salinity and temperature of the water since these factors have a bearing on horseshoe crab behavior.

The count information is used to determine changes in population over time and develop an understanding of horseshoe crab behavior in this region. The data are also critical in determining the health of the overall environment, particularly in Great Salt Bay.

Coastal Rivers is a nonprofit, member-supported, nationally accredited land trust caring for the lands and waters of the Damariscotta-Pemaquid region by conserving special places, protecting water quality, creating trails and public access, and deepening connections to nature through education programs. For more information, email info@coastalrivers.org or visit coastalrivers.org.