ANSWER 1

Written response:

All organisms have a range of environmental conditions that are suitable to live and function in. For example, an ideal temperature for humans is around 18-24 degrees Celsius. Any warmer or colder and we may have to alter our environment to reach temperature ideal for normal functioning (e.g. putting on a jumper or turning on a fan).
Estuaries and coastal environments are highly variable systems and the species that inhabit these areas can usually operate in conditions outside of their optimal tolerance for a short period of time. For example, after heavy rain the salinity levels in estuaries can drop temporarily, estuarine species are generally well adapted to these temporary changes. However, ocean conditions are now changing more frequently, intensely and for longer durations, these changes include increasing temperature (e.g. ocean warming and marine heatwaves) and salinity changes (e.g. droughts, floods, rainfall) which are now occurring outside of species tolerance levels and/or for excessive periods of time.
Species can respond to these changes in a range of ways – from moving to more suitable conditions temporarily or permanently (e.g. range contractions & extensions), to physiological or behavioural adaptations (e.g. reduced reproduction). However, not all species can adapt or relocate quickly enough, especially those with limited mobility or strong site fidelity (e.g. immobile species like sponges and anemones) and narrow tolerance ranges – this can lead to declines in abundance through mortality. All of these responses can impact species abundance and availability in estuaries and coastal zones.