Estuary Survival The Rules of Life This is a game where we will learn about how challenging life in an estuary can be. We will see what it takes to make it to adulthood and live on to make the next generation. Listen carefully as we go over the rules for Estuary Survival!

The Players Dungeness crab and Coho salmon are two of the multitude of animals that depend on the estuary for survival. They grow up in the rich waters of the bay where they compete for habitat and food with many other creatures. Yet, each year, millions of these fish and crabs will survive and go on to become adults. In the game of Estuary Survival, we will learn about what kinds of circumstances affect the survivorship as the class becomes the hunters and the hunted.

Dungeness crab – Cancer magister 5mm across carapace – megalops 12mm across carapace – 1st instar 20mm across carapace - juvenile Dungeness crab are born in the ocean, yet as young zoea floating in the ocean, many of them will be swept into the shallow waters of the estuary where they will settle on the bottom. Here they will feed and grow, undergoing dramatic changes where they shed their entire shell or exoskeleton in a process known as molting.

Coho salmon – Oncorhynchus kisutch 35mm fork length – parr 50mm fork length – smolt 65mm fork length - juvenile Coho salmon are born in freshwater streams and in the first year of their life, they may swim down into the estuary where they will feed and grow. Their bodies will also change as they adjust from the freshwater conditions of the creek to the salty waters of the ocean.

Predator/prey cards The Striped Bass represents a non-native fish. These fish appear on the predator/prey cards. Predator/prey cards describe a situation with consequences for crabs and salmon in the estuary depending on factors such as your size and location. Predators and the animals they prey upon are part of a never ending cycle of survival and loss. Those that survive will live on to the next round.

Estuary condition cards Estuary condition cards describe the tides and different factors that will impact life in the estuary. The habitats below the low tide line include only the open water channel and the eelgrass meadows. If you’re crab or salmon occupies a square that has any of a particular kind of habitat in it, you may claim that habitat. For example, if you have any bright green eelgrass in your square, you are protected by the eelgrass. Conditions in the estuary are always changing as the tide rises and falls, the seasons change, and unpredictable events cause damage to the environment.

Estuary Survival gameboard

Estuary Survival gameboard Low tide lines

Estuary Survival gameboard Estuary zones

Estuary Survival gameboard Habitat legend

Habitat and tide zones The estuary playing board is divided into three areas – low, mid, and upper estuary which are divided by lines across the board. The low tide line is marked in black. The habitat zones cross over these areas. To claim a habitat, at least 50% of your square must be covered by this habitat. Four habitat zones exist Eelgrass (bright green) Open water (blue) Mudflats (brown) Salt marsh (dark green) The playing board is divided into three areas and four habitat zones. Like the constantly changing conditions of the real estuary, these areas and zones will determine how well individuals will survive.

Your scorecard Investigator’s name Common name of the animal Genus and species Size and life stage Three questions Scoring box for each round Each player will have a scorecard where they will record all of the information listed before beginning to play.

Tokens are worth 20 points each 5mm crab megalops 35mm salmon smolt 50mm salmon smolt 12mm crab larva Each token is worth 20 points at the beginning of the game. This could be considered to represent 20 individuals in a sub-population. Size and species have particular advantages and disadvantages. 65mm salmon smolt 20mm crab larva

sample scoring for 3 rounds Position Habitat Fate C7 Eelgrass My crab survived an oil spill because he was in the mid-estuary. My crab survived because the eelgrass provided cover from cormorants. My crab grew one size class because the high tide brought food from the ocean. This is an example of what a scorecard might look like after three rounds of play. In the first round, an estuary condition card read that an oil spill at high tide killed all crabs in the lower estuary, but this crab was in the mid-estuary. In the next round, eelgrass habitat protected him from birds feeding. In the third round, he grew by one size class because food was available.

Graphing survivorship Survived round 1 8 crabs 5mm 5 crabs 12mm 6 salmon 35mm 3 salmon 65mm Survived round 2 Survived round 3 An Excel spreadsheet template is included in this TIDES activity so that the class can tally totals for each category of crab or salmon and then create a chart displaying how many individuals survived each round. From this data, the odds of survival can be calculated.

This chart depicts a sample round where 32 individual crab and salmon started out and only 11 survived after 4 rounds. Results may vary greatly depending on the sizes and types of animals chosen.