Influence of macrohabitat preferences on the distribution of European brook and river lampreys: Implications for conservation and management

Abstract

a b s t r a c tThe European river lamprey, Lampetra fluviatilis (L.), and the European brook lamprey, Lampetra planeri (Bloch, 1784), are considered highly threatened in Portugal. However, the lack of information about the ecology and distribution of these species poses difficulties to the identification of concrete actions directed to their conservation. A total of 401 sampling sites, randomly distributed throughout the entire Portuguese mainland territory were selected, and Lampetra sp. ammocoetes presence or absence checked with electrofishing. These data, together with 11 macrohabitat predictors, were analyzed using Boosted Regression Trees (BRTs). The BRT models consistently identified five environmental variables as the most important for predicting the distribution of European brook and river lamprey ammocoetes: altitude, distance to coast, sand, maximum temperature of the warmest month and precipitation of the driest month. The relationships of these variables with the species probability of occurrence suggest that lampreys occur in low altitude river stretches (<170 m), relatively close to the coast (<150 km) and with a sandy substrate (>70% sand). In addition, intermediate values of temperature and precipitation were also found to have a positive correlation with the species occurrence. A map with the probability of occurrence of Lampetra sp. in Portugal was generated and stretches of rivers were delimited with different conservation priorities. Rivers classified with the highest level of conservation priority were considered to be proposed as Special Areas of Conservation, under the Natura 2000 Networking Programme.

Lampreys: Biology, Conservation and Control

“…In a western Washington stream, Stone and Barndt (2005) found that Pacific lamprey abundance per reach was negatively associated with stream gradient. Ferreira et al (2013) likewise found that GIS-derived slope did not improve the performance of their model predicting the distribution of European river and brook lamprey larvae in Portugal at a macrospatial scale. Neeson et al (2007) attempted to predict the distribution of suitable larval sea lamprey habitat at several spatial scales using water surface slope (as measured in the field) and GIS-derived geomorphic values within the East Branch of the Chagrin River, Ohio.…”

“…Lampreys are generally found north and south of the 20° isotherm, with average lethal temperatures around 28 °C (Potter 1980a). In their study evaluating the influence of 11 macrohabitat variables on the distribution of European river and brook lampreys in Portugal, Ferreira et al (2013) found that lampreys were found in areas where the average maximum temperature of the warmest month did not exceed 30 °C. reported that high water temperatures may be responsible for the absence of lamprey ammocoetes from the lower sections of Lake Ontario streams during the late summer.…”

“…On a global scale, temperature is the environmental variable that best explains lamprey distribution (Ferreira et al 2013). Lampreys are generally found north and south of the 20° isotherm, with average lethal temperatures around 28 °C (Potter 1980a).…”

“…Dawson and Jones (2009) studied four Great Lakes streams, and found that streams with higher sea lamprey survival-to-age-1 had distributions of spawning and larval habitats that were most favorable to ammocoete production (i.e., the largest amount of spawning habitat in the upper reaches and the largest amount of preferred larval habitat in the lower reaches). Distribution of ammocoetes of migratory species (e.g., European river lamprey and sea lamprey) is also related to adult access to spawning habitats from their feeding grounds, with distance from a large water body (e.g., sea, estuary, or lake) and presence of potential migration barriers influencing ammocoete abundance (Goodwin et al 2008;Ferreira et al 2013).…”

“…However, the situation is now changing, with proposals for lamprey conservation put forward by biologists in Europe (e.g., Maitland and Lyle 1992;Ferreira et al 2013) and in North America (e.g., Mesa and Copeland 2009;Renaud et al 2009;Swift and Howard 2009) in recent years. The outlook for these fascinating and valuable animals is now a much more optimistic one.…”