5.5 Carrying Capacity and Limits of Acceptable Change
Think about being in a kitchen, cooking for Christmas dinner (Fig.1_Ses5.5_Vecteezy).
You are alone, but suddenly all the guests start to come in the kitchen ready and willing to help you. The pot with the sauce falls down on the floor because someone accidentally hurts it. After that you start kicking out most of your ‘helpers’ from the kitchen. There is a mess, but with 3-4 people in the kitchen you are able to restore the order andsave the meal, different from the previous one, but Christmass still on! The limit of 3-4 people is the carrying capacity of the “kitchen ecosystem”.
The “Carrying Capacity” (CC) is the levels of sustainable use, for fishery, tourism or other activities, below which the ecosystem can cope and remain resistant and/or resilient to the use, but above which detrimental changes can occur. In other words, CC is the turning point in which an area starts to fall in adverse conditions as a result of the number of incoming visitors.
Hawkins and Roberts (1997) recommended that the figure of 5,000 – 6,000 dives per site per year could be used to estimate the overall capacity of a protected area to support recreational diving, depending on the number of dive sites available (Fig.2 & 3_Ses5.5). However the CC can vary with:
• number of divers;
• types of divers;
• their training – education and guidance;
• the types of coral growth-forms (e.g. fragile / stout);
• nature of the site (slope, current, community structure);
• natural levels of coral breakage;
• access to a dive site (reef walking, snorkeling or from a boat);
• type of diving (drift, swim, photography etc.);
• whether the dive boat is moored or is anchored;
• types and amount of infrastructure support.
Another important concept, similar to the previous one, is the “Limit of Acceptable Change” (LAC) (Stankey GH, 1985 and Roman GSJ, 2007). It is the degree of change or impact that will be tolerated for the resources in use. It implies the preliminary process of defining the desired resource conditions and the consequent actions necessary to maintain or achieve them. Numbers are not a concern, but the LAC focuses on the impacts. In this case a management agency determines what levels of diver-, visitor- or infrastructure- caused change or damage are acceptable (e.g. decline in coral cover of 5%). Compliance monitoring and reactive management then aim to maintain a particular tourism site within those levels. Indeed, the LAC involves a whole process (i.e. assessment, analyses and action).
However it is necessary both a clear definition of what is acceptable (e.g. damage must not exceed the natural range of coral damage or, damage shall not exceed 10% of natural damage levels) and a clear identification and specification of monitoring methods applied. The management agency must identify the source(s) of impact and stop or control the source (not just the number of divers, but also maybe their lack of knowledge!).
The similarities between CC and LAC could be summarized in four major points:
• deal with undesirable impact of a tourism area utilization;
• set standards on how a tourism area should be managed to maintain sustainable state;
• help the stakeholders take actions against the adverse effects;
• based on human judgment.
To sum up, they both deal with undesirable impacts and they set standards on how the stakeholders should act to manage the issues.