LIFE IN SKINNY WATER: OBSERVATIONS OF JUVENILE DIAMONDBACK TERRAPINS (MALACLEMYS TERRAPIN) UTILIZING SHALLOW WATER HABITATS

Relatively little is known about the juvenile years of many turtle species, particularly the habitats used. Prior turtle studies found that juveniles use different habitats compared to adults, and therefore, juveniles are typically undersampled. Diamondback Terrapins (Malademys terrapin) inhabit salt marsh, island, and mangrove habitats along much of the Atlantic and Gulf Coasts of the USA. Much information is known about adult terrapin ecology, but little information exists for the juvenile life stages. While sampling for terrapins in southwestern Louisiana from 2011-2016, I captured 20 juveniles (<9.5 cm PL) by Tyke net and 15 juveniles by manual searching via airboat. Juveniles were only 3.1% of tyke net captures (0.07/net day) and 6.0% of manual searching captures (0.44/airboat hour). Juveniles were observed exclusively in shallow water habitats (< 1 m), with many captured in < 10 cm of water. Fyke net bycatch of Alligator Gar (Atradostetts spatula), a top predator, increased above this depth. Juveniles likely use shallow water for a multitude of reasons. These may include increasing survival by having fewer predators and more cryptic habitats, while also promoting higher growth rates via improved thermoregulatory opportunities (i.e., shallow, warm water), fewer osmotic challenges, and possibly competitive avoidance with adult terrapins. The lack of juveniles in prior studies is likely due to a combination of sampling methodology, habitats sampled, and crvpsis. These observations further support that high marsh is important habitat for juvenile terrapins and that such habitats should be included into terrapin and/or coastal conservation planning.