CHIRONOMIDAE FROM MARINE COASTAL ENVIRONMENTS NEAR ST JOHNS, NEWFOUNDLAND, CANADA

Chironomid larvae and adults were collected from rock pool and interti dal sites between 1990 and 1994 on the exposed Atlantic coast and in m ore sheltered bays near St. John's. From several thousand specimens co llected, 16 chironomid taxa were identified. Two were from intertidal habitats and the remainder occurred in rock Fools. In intertidal habit ats Halocladius variabilis was abundant in summer among clumps of fine filamentous algae, e.g. Pilayella littoralis. The previous Nearctic r ecords of this chironomid were from Hudson Bay and Greenland although it is widespread in northern Europe. The other intertidal species, Tel matogeton japonicus, was recorded from one site, a rock outcrop on a b each in the mouth of a small stream. This Holarctic species has not be en reported previously north of New York on the Atlantic coast. The ro ck-pool communities were dominated by Psectotanypus dyari, Cricotopus sylvestris, Psectocladius sordidellus gp, Orthocladius dubitatus, Chir onomus riparius, and Tanytarsus sp. These taxa are known to tolerate s ites with elevated salinity and/or conductivity and thus are present i n polluted sites inland. The other eight chironomid species were rare and most were found at only one site. An exception was the Metriocnemu s sp. collected in very low numbers at three sites and also collected previously during a survey of rock pools for larval mosquitoes in the same area. The current study shows that a diverse coastal chironomid c ommunity is present in the cold ocean habitats of eastern Newfoundland . The community is made up of both arctic and temperate faunal element s with widespread distributions not confined to coastal habitats. Rang es of temperature, salinity, conductivity and pH for the common specie s occurring in the rock pools are provided. The results suggest that c oastal rock pool habitats could be a natural laboratory for studies on the evolutionary ecology of pollution tolerance in chironomids.