Use of flathead mullet (Mugil cephalus) in coastal biomonitor studies: Review and recommendations for future studies

Abstract

There has been a widespread world-wide use of flathead mullet, Mugilcephalus, in fish biomonitor studies within the coastal zone. This review summarises this research field, focusing on heavy metals, and considers the implications of the accumulated data. Differences in sampling methodology, tissues analysed and units of reported data provide challenges in assessing and benchmarking these biomonitor studies. The benthic feeding strategy of M.cephalus invariably increases exposure risk relative to middle or upper water column feeders, nevertheless contaminant accumulation via direct and indirect pathways was regulated sufficiently such that toxicants were below food guidelines in most coastal regions (32 of the 49 examined). Human health issues can arise if fish are consumed from heavily industrialised regions. Recommendations are provided for future biomonitoring studies, based on the results for M. cephalus but relevant for fish species more broadly, to provide more comparable data so that managers can benchmark against local conditions.

Mugilid Fish Are Sentinels of Exposure to Endocrine Disrupting Compounds in Coastal and Estuarine Environments

“…It is advisable that they display a restricted home range, with a well-known biology and showing sensitivity but resilience to pollutant exposure. Mugilids are able to endure highly polluted environments, displaying several of the characteristics required for estuarine sentinel species [48,49,50,51]. Their worldwide distribution (Figure 1) and their similar life histories allow the comparison of responses in different geographical areas.…”

“…Due to their benthic feeding strategy mullets tend to accumulate more contaminants than other fish species [50,85,86]. Thus, they are ideal organisms for the identification of the levels of metals [49,50,87,88] or organic contaminants such as PCBs and organochlorine compounds [56,85,89] accumulated in tissues.…”

“…Thus, they are ideal organisms for the identification of the levels of metals [49,50,87,88] or organic contaminants such as PCBs and organochlorine compounds [56,85,89] accumulated in tissues. Biological endpoints analyzed in mullets include pollution mediated skeletal deformities [90], oxidative stress and biotransformation enzyme responses [48,91], genotoxic responses [92,93] and endocrine disruption effects (see below).…”

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“…At least one species, flathead grey mullet, Mugil cephalus L. 1758, is becoming endangered and rare (Glamuzina & Bartulovic, 2010). Mullets have been proposed as sentinel organisms of environmental pollution using both wild and caged individuals (Whitfield et al, 2012;Diaz de Cerio, Rojo-Bartolome, Bizarro, Ortiz-Zarragoitia, & Cancio, 2012;Waltham, Teasdale, & Connolly, 2013) and are sensitive organisms to EDCs (Puy-Azurmendi et al, 2013;Ferreira, Antunes, Gil, Vale, & ReisHenriques, 2004;Aoki et al, 2010). Therefore, the present study was aimed to document the occurrence of intersex, if any, in the grey mullet, Mugil cephalus population fished off from Kovalam coast, East coast of India.…”

Why “Biomonitoring”?

“…For me, the stubborn doctor again, biomonitoring in mosses [42][43][44], lichens [45] and leaves [46,47] or needles [48] of trees or even feathers [49] was simply another kind of ambient monitoring where the biological matrix only serves as a sort of passive sampler. Sometimes the species sampled might even serve as food for humans so that wildlife biomonitoring has a direct relevance for human health [50][51][52]. The picture turns completely upside down when effects on wildlife and ecosystems are seen in their own right [53].…”