Sun exposed temperature data from Sea Point, 4 April to 9 May 2023

To better understand the physiological effects of marine invertebrates to changing environmental conditions, long-term monitoring which captures the natural variability of environmental parameters is required. In this way, experimental findings can be related back to field conditions, and better predictions can be made as to how marine invertebrates, particularly in the harsh intertidal, will fair with rising temperature. In May 2020, Cape Sea Urchins, Parechinus angulosus, were collected from intertidal rock pools at Sea Point, which is situated along the southwest coast of South Africa. After chronic incubation in low pH conditions at The Department of Forestry, Fisheries and the Environment's (DFFE) Sea Point Research Aquarium, their response to thermal stress was investigated in recent experimental trials. To calculate the thermal window for these marine invertebrates, both habitat temperatures, as well as their threshold temperatures are required. The latter was obtained by examining the Critical Thermal Maximum temperatures (CTmax), i.e. the temperatures at which organisms respond with uncoordinated mobility, whereas habitat temperatures are available through the deployment of temperature loggers in the intertidal pools inhabited by these organisms. Apart from rockpool temperatures recorded in Sea Point, Cape Town, a HOBO TidbiT temperature logger was also installed on a nearby structure: 33.92074 S, 18.38051 E to record temperature in a sun-exposed position. An alternative to placement on fully exposed rocks where it would be subjected to theft. This data will allow for an indication of the most extreme temperatures in the vicinity of the pool. Here we present the cleaned up version of the temperature measurements from the 4 April to 9 May 2023.