Rocky Shore - Introduction

Intertidal rock habitats are widespread throughout the UK. In Scoland, the coastline can be characterised by lengths of intertidal sediments which are interspersed with rocky stretches, promontories, and headlands (Austen et al, 2011). Rocky shore habitats are often found in association with other similar habitats, such as below cliffs and cliff slopes (Lake et al, 2015). Rocky shore habitats are influenced by wave action, light, nutrients, and temperature, with rocky shores often able to be split into different zones; lower, middle, upper, and splash. As these zones experience different levels of salinity, light, nutrient availability and temperature, therefore species adapted to the differing conditions will inhabit each zone (Lake et al, 2015).

Out of an estimated 9000km length of Scottish coastline, 4800km (54%) is comprised of rock with an additional 1010km (11%) comprised of rock with other sediment types. A higher proportion of rock can be found along Scottish coastlines in areas with more wave exposure (Scottish Government, 2020) (fig. 1).

Biodiversity:
Rocky coastlines support a rich diversity of wildlife, including barnacles, limpets, crabs, snails, sea squirts, and anemones. Seaweeds (also known as macroalgae) found along the coast can be split into three main categories by colour: browns, reds, and greens with key examples including sea lettuce (Ulva lactuca), oar weed (Laminaria digitata), and coral weed (Corallina officianalis) (Scottish Seabird Centre, n.d.). Along the lower shore is where kelp species (Laminaria sp.) and invertebrates such as common starfish (Asterias rubens) can be found. The upper shore is inhabited by species such as spiral wrack (Fucus spiralis) and small periwinkle (Melarhaphe neritoides), and the splash zone above is dominated by lichens such as black tar lichen (Verrucaria maura). Birds utilise rocky shorelines to feed, particularly waders such as purple sandpiper (Calidris maritima) (fig. 2) and turnstone (Arenaria interpres) and small passerines such as rock pipits (Anthus petrosus) (Scottish Government, 2020; Scottish Seabird Centre, n.d.).

Ecosystem Services (Austen et al, 2011):
Rocky shores  provide a number of ecosystem services, following the four classifications introduced in the Millenium Ecosystem Assessment (2005).

Supporting: Like a number of other marine and coastal habitats, rocky shores support primary production and nutrient cycling.

Provisioning: In some locations in Scotland, seaweed is provisioned by rocky shores for food. Rocky shores provide space for diversity of wild species, from invertebrates to plants to birds.

Regulating: Rocky shore, like many coastal habitats, provides hazard regulation ecosystem services as a hard sea-defence. Rocky shores give protection from erosion, coastal flooding, and wave damage by absorbing and dissipating wave energy.

Cultural: Rocky shores are of high cultural importance, used as a space for eduction and scientific study, an area for wellbeing and exercise (.e.g rock-pooling), and as a source of aesthetic views and inspiration.

Conservation Status:
Intertidal boulder communities are a Priority Habitat on the Scottish Biodiversity List (NatureScot, 2020).