The seagull is the first symbol Chekhov used to title a play, written before The Cherry Orchard. The image of the seagull changes meaning over the course of the play. First, in Act One, Nina uses a seagull to describe the way she is drawn to the lake of her childhood home and her neighbors on Sorin's estate. In this case, the seagull represents freedom and security.
In Act Two, Treplev shoots a seagull and gives it to Nina. Treplev tells her that one day he will be dead in Nina's honor just like the seagull. Later, Trigorin uses the seagull as a symbol for Nina and the way he will destroy her, as Treplev destroyed the seagull. Treplev mentions that after Nina had the affair with Trigorin, she has written him letters signed, "The Seagull." In Act Four, Nina returns to the estate and calls herself the seagull then corrects herself, describing herself as an actress. The seagull changes its meaning from freedom and carefree security to destruction at the hands of a loved one. It symbolizes freedom at first and then dependence. The seagull also serves as a foreshadowing device. Nina fulfills Trigorin's prophesy of destroying her just like the seagull and Treplev kills himself in Nina's honor at the end of the play when she still does not love him.
Chekhov's setting of the play around a lake repeats and emphasizes its purpose with Treplev's setting of his play by the lake in Act One. The lake represents both Treplev and Chekhov's desire to move to a more naturalistic theater not limited by three walls. The lake means several different things to the play's characters. The lake is a place of reflection, respite, and escape. Trigorin goes there by himself to fish. Treplev goes to the lake to mope and reflect, perhaps also, to get attention for his bruised ego. To Nina, the lake magnetically draws her to it. It is a place to roost, to feel secure and at home when there is no home to be found. To Nina the lake also represents curiosity and exploration of childhood. She tells Trigorin that she knows all of the little islands on the lake. Treplev tells Nina that losing her love feels like the lake sunk into the ground. To him, losing her affection feels like losing a recognizable place, a place of peace and renewal. Treplev's metaphor describes a life-source—the lake—drying up and disappearing. This is how Treplev feels about his own life in relation to his loss of Nina.
Chekhov uses weather to create the tone for his stories and in his plays. The weather reflects the characters' state of mind and foreshadows upcoming events. For instance, before Nina returns to visit Treplev the weather is stormy and windy as if the storm conjured up Nina and brought her to the estate. Storms usually reflect a change in temperature and likewise, weather is a signal for change in The Seagull.