Identification of Phymatolithon lamii (Me. Lemoine) Y.M. Chamberlain 1991 following bleaching in the upper intertidal zone of the Minas Basin, Nova Scotia, Canada

Abstract

Objective: To identify an unusual encrusting calcareous organism found growing on upper intertidal rocks along the coast of the Minas Basin, Nova Scotia, Canada, which was thought to potentially represent a new, perhaps invasive species to the area. Methods: Observations were made of the organism growing in situ and of intact and dissected specimens under microscopes in the laboratory. Taxonomic keys were used to determine probable identity of the organism as a tunicate, sponge, bryozoan, marine lichen, or coralline red alga. These keys were then further used to identify samples to species. Results: The organism was determined to be Phymatolithon lamii (Me. Lemoine) Y.M. Chamberlain 1991, an encrusting coralline red alga native to the study region. This species normally occurs in the subtidal zone, so its occurrence in the high intertidal zone was unusual and resulted in the alga becoming bleached and taking on an unusual appearance. Conclusions:The sample did not represent a new or invasive species to the study area. However, occurrence of this species on the high intertidal zone was novel and may have resulted from unusual climatic and/or oceanographic conditions in the study area in 2015 that allowed this alga to settle and grow in the intertidal zone for a time before death and bleaching occurred. Events such as this resulting from climate change may negatively impact recruitment to populations of coastal marine species and should be investigated further.

Dramatic decline and limited recovery of a green crab (Carcinus maenas) population in the Minas Basin, Canada after the summer of 2013

“…(B) Photograph of the study site, taken toward the shore from the low tide mark from the approximate location of the red dot in (C); reefs surveyed for crabs are visible mainly on the right and left sides of the image. (C) Map showing details of the study site, including bottom substrate types on the intertidal zone; solid gray area is land, white areas are subtidal, black areas are rockweed reefs where crabs were sampled in this study, asterisk is the location of a previous study ( Quinn, 2016 ). (D) Map showing the location of the study site (solid square) and Minas Basin (rectangular outline) within Atlantic Canada.…”

Dramatic decline and limited recovery of a green crab (Carcinus maenas) population in the Minas Basin, Canada after the summer of 2013

“…The left map shows details of the study site, including bottom substrate types on the intertidal zone; solid gray area is land, white areas are subtidal, black areas are rockweed reefs where crabs were sampled in this study, asterisk is the location of a previous study (Quinn, 2016). Right map shows the location of the study site (red square) and Minas Basin (rectangular outline) within Atlantic Canada.…”

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“…1). A previous study (Quinn, 2016) reported observations at the boundary between the upper and middle intertidal zones at this location. A large middle intertidal mud flat is located to the north of this area, just outside of the cove (Fig.…”

“…When extremes of seasonal temperatures coincide due to such climatic changes, the effects on biota can be considerable (e.g., Quinn, 2016). Excessively hot summers in recent years may have played a role in observed declines because heat stress leads to decreased performance and survival in decapod crustaceans, especially in larger-bodied benthic life stages that tend to have lower heat tolerance (e.g., Byrne, 2011).…”

“…Most environmental data outlined above, including daily mean air temperature (in °C), variability (= standard deviation, or SD) of daily air temperature, minimum daily air temperature, maximum daily air temperature, total daily precipitation (in mm), variability (SD) of daily precipitation, maximum daily precipitation, direction of the maximum-speed daily wind gust(s) (in tens of degrees relative to north (0°)), variability (SD) of wind direction, mean daily wind gust speed (in km h -1 ), variability (SD) of wind gust speed, and maximum daily wind gust speed, were calculated per season based on daily data from Environment Canada (Government of Canada 2018) as tracked at the weather station in Parrsboro, NS. Water temperature data were not recorded and reliable data for this nearshore area could not be obtained from online or modeled databases, so air temperature was used as a proxy for temperature experience by crabs; this is reasonable because for half of each day intertidal crabs are exposed to air rather than water temperatures (Boudreau & Hamilton 2012, Quinn 2016. Values of the NAO index for each season were obtained from the Hurrell et al (2003) database (National Center for Atmospheric Research Staff 2018).…”