Complex sentence: It should be noted that not all dark spots observed in early spring are associated with spider landforms, however, a preponderance of dark spots and streaks on the cryptic terrain are associated with the appearance of spiders later in the season.
Split into simpler sentences: It should be noted that not all dark spots observed in early spring are associated with spider landforms. However, a preponderance of dark spots and streaks on the cryptic terrain are associated with the appearance of spiders later in the season.