Freshwater systems – the poor relations of conservation biology?

Posted on December 15, 2011

Despite widespread agreement on the value of protected areas in habitat and species conservation, proposals for freshwater reserves have received serious attention only in recent years.  Protected area design has had a very strong terrestrial focus and in many instances freshwater environments have received protection only as incidental elements of largely terrestrial landscapes.  But how much of a safety net do terrestrially oriented reserves provide for aquatic features?  This question has been addressed by treating the state ofMichigan, a case study.  Located in the Great Lakes region,Michigancontains over 11,000 lakes and over 90,000 km of streams, and a high proportion of state land is protected.   The relative representation of different types of aquatic environment (wetlands, riparian strips, groundwater recharge areas) withinMichigan’s reserves was assessed.  Wetlands were represented significantly more often than would be expected by chance, partly because the declaration of parks and reserves has favoured areas that have low suitability for agriculture and other economic uses.  In contrast, riparian zones, especially those along headwater streams, were very underrepresented.  This was a surprising and significant result given the fact that headwater streams represent a large majority of total river length and have high biodiversity value.  On the whole, groundwater recharge areas were represented in proportion to the area of the reserve network within watersheds, but it was noteworthy that the region with the state’s highest groundwater recharge rates was almost entirely unprotected.  Finally, the occurrence of rare animals at the local scale within protected areas was lower for aquatic species (10%) than for wetland (24%) or terrestrial (30%) species.  While half of the known populations of rare insects fell mainly within reserves, over 90% of local populations of rare fishes and aquatic molluscs were unprotected.  The uneven coverage of aquatic habitats and species shows that terrestrial reserves don’t provide proportional protection for freshwater ecosystems.  InMichigan’s case, although 22% of its area is managed on a multiple use basis, with conservation as one consideration, only 2% of the state enjoys long-term, stringent protection.  Aquatic protection can be improved by designing new reserves to protect terrestrial and aquatic features simultaneously, and by upgrading the conservation status of some existing multi-use zones.

Reference:     Herbert, M.E., McIntyre, P.B., Doran, P.J.,  Allan, J.D. & Abell, R.   2010.  Terrestrial reserve networks do not adequately represent aquatic ecosystems.  Conservation Biology 24 (4), 1002–1011.