Biodiversity of Holocene marine fish of the southeast coast of Brazil

Middens are archaeological sites dating between 8,000 and 1,000 years before present and are commonly found on the Brazilian coast. Data were collected from 68 middens allowing an inventory of 142 fish species, most of them recorded in no more than five sites. Conversely, Micropogonias furnieri and Pogonias cromis had the highest frequencies of occurrence. The biogeographic, ecological and economic data showed that most of the identified fish are widely distributed in the Western Atlantic (59.72%) and inhabit estuarine environments (53.99%), while most species have a demersal habit (35.92%) and exhibit oceanic migratory behaviour (28.87%). Lastly, the surveyed fish are predominantly carnivorous (72.54%) with some commercial value (96.48%). Chi-squared tests comparing midden inventory and current ichthyofauna checklists failed to show significant differences between them (p > 0.99). Thus, the results indicate that zoo-archaeological fish remains are key evidence of Holocene biodiversity and may help the establishment of more complete baselines.


Introduction
Biodiversity-related research has developed significantly since the 1990s, when ecologists worldwide, concerned with anthropogenic effects on ecosystems, intensified their studies of environmental issues (Amaral & Jablonsky 2005, Lewinsohn & Prado 2005).Biodiversity is defined by the Convention on Biological Diversity as the variability among living beings of all origins, including terrestrial, marine and other aquatic ecosystems, and their associated ecological complexes, including intra-and inter-species as well as ecosystem diversity (Arruda et al. 2000).
Recently, the Census of Marine Life raised the estimated number of known marine species from approximately 230,000 to between 1 and 1.4 million; more than 1,200 new species were identified among specimens collected in known and previously unexplored waters (Costello et al. 2010).Furthermore, in a review of research related to Brazilian biodiversity, Siqueira et al. (2015) found that only 21% of 1,156 references from 2009 to 2014 addressed the richness of aquatic species, indicating that the marine environment remains little studied and is therefore largely unknown.Finally, baselines for long-term studies of marine biodiversity are scarce (Knowlton & Jackson 2008, Pinnegar & Engelhard 2008).
Baselines are reference biodiversity inventories that directly assess the species composition of a specific site for a given spatial extent and time.The data generated by such inventories are one of the most important tools for the conservation and management of natural areas, especially the associated endangered species (Silveira et al. 2010).The establishment of baselines is particularly important for the conservation of marine fish because this group is intensely exploited due to their commercial value and account for a significant share of global fishery production.In Brazil, fisheries have been key to the development of the country, concentrating 70% of the population near the coast, and the sea plays a key role in its history, culture and economy (Rosa & Lima 2008).
To be as accurate as possible, reference inventories of ichthyological fauna should include not only current data but also historic and prehistoric (fossil/sub-fossil) data as well (Furon 1969, Warwick & Light 2002, Willis & Birks 2006, Froyd & Willis 2008, Stahl 2008).However, collecting data on the species compositions of the past is complicated because fossil/sub-fossil records are largely characterised by being incomplete; that is, the biological data (species morphology, richness, diversity and evenness, among others) preserved in those records are influenced by non-linear modifications that occur from the time of death to the final burial of an organism (Ritter & Erthal 2016) and the species preservation potential (Prummel & Heinrich 2005).Therefore, prehistoric records are relatively scarce (Bittencourt et al. 2015).
However, there are some Holocene species composition records from sources including beaches, death assemblages and middens.Beaches and restingas originated in the Holocene, but their characteristics prevent the establishment of a chronology (Lacerda et al. 1984).Conversely, death assemblages allow for accurate chronological estimates and have the great advantage of being natural, thus showing actual tanatocenoses, but these formations are rare along the Brazilian coast (Ritter & Erthal 2016).However, middens, which are archaeological sites dating between 8,000 and 1,000 years before present (BP, according to the convention before 1950), are commonly found on the Brazilian coast and allow a chronology to be established because they show a stratigraphic sequence of different species compositions (Kneip et al. 1988, Gaspar 1998, Scheel-Ybert et al. 2009, Klokler et al. 2010).
Middens were built by groups of prehistoric fishermen-gatherers-hunters, which explains why they are found in estuarine areas at the intersections of rivers and the sea.These sites contain a wealth of resources including sediments, coal, lithic material and, above all, faunal remains.High numbers of molluscs and crustaceans, including sea and sand crabs, as well as echinoderms and fish have been found among the marine zoo-archaeological remains recovered from middens (DeBlasis et al. 2007, Figuti 1993, Lima 2000, Lima et al. 2003).
For fish species, their zoo-archaeological remains indicate their usefulness to midden populations, so most species recorded at these sites have a cultural meaning and show sociocultural and identity relationships and spatiotemporal economic characteristics (Figuti 1998, Barbosa-Guimarães 2013, Wagner & Silva 2014, Lopes et al. 2016).Accordingly, because the ichthyological remains in middens represent the diversity of prehistoric fishes obtained from a selective catch, this data source underestimates the diversity of Holocene fish.That is, the species diversity of the remains found in the middens is lower than that in natural communities (Gonzalez 2005, Costa et al. 2012).
Although midden fish records underestimate natural diversity, they are a key source of information on the ichthyological fauna of the past because prehistoric people could only have caught the fish available in the environments at the time.Furthermore, by-catch occurred; that is, species with no known anthropological relevance were incidentally fished with target species (Reitz & Wing 2008, Villagran & Gianini 2014, Beuclair et al. 2016).Therefore, midden records are a good indicator of Holocene biodiversity, providing data on fish species composition, abundance, distribution and richness as well as cultural information (diet, fishing gear, ritualistic symbols, ornaments and artefacts) (Souza et al. 2010a, Souza et al. 2010b, Faria et al. 2014, Mendes et al. 2014, Rodrigues et al. 2016a, Rodrigues et al. 2016b, Beuclair et al. 2016, Silva et al. 2016).
Thus, although middens are artificial accumulations (that is, built by prehistoric populations) of biological material, the presence or absence of species at these sites provides sufficient data to create a taxonomic list that may be useful for defining a historical record of biological diversity (Stahl 2008), so this study presents an inventory of marine ichthyological biodiversity from southeast Brazilian middens.This list is the first comprehensive inventory of Holocene fish fauna from this region and may help elucidate past natural ocean events, enabling the establishment of more complete baselines to inform conservation and management measures.

Methods
The inventory was constructed from an extensive bibliographical survey of the libraries of universities and institutions with archaeological collections from sites along the southeast coast of Brazil as well as online databases (Web of Knowledge, Scientific Electronic Library Online -SciELO, Google Scholar and the Thesis Database of the Brazilian Federal Agency for the Support and Evaluation of Graduate Education (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior -CAPES)).The data sources included scientific articles and books, thesis, dissertations, monographs and technical reports.
The list of species was analysed in terms of absolute and relative species richness and absolute and relative frequencies of occurrence.Absolute species richness is the number of species present at a sampled site, while the relative species richness is the ratio between that number and the total number of species.Similarly, the absolute frequency of occurrence is the number of sites at which a specific species occurs, and the relative frequency is the ratio between that number and the total number of sites.
Furthermore, taxonomic, biogeographic, ecological and economic data on the inventoried species were collected from the FishBase database (Froese & Pauly 2017) and categorised by distribution (range of occurrence), environment (habitat), habit (way of life at specific locations in the water column), behaviour (migratory movements), feeding guild (food requirements) and commercial value (demand for the species in the fish market).
The checklists constructed by Bizerril & Costa (2001) for Rio de Janeiro and Menezes (2011) for São Paulo were compared along with the inventory from the midden zoo-archaeological remains from this study to current ichthyological inventories for the same regions, and the species catalogued in speciesLink, a digital information system that integrates primary data from scientific collections in real time, for Espírito Santo were surveyed.Furthermore, a chi-squared test (χ 2 ) was performed to assess whether the ratio of commercial and non-commercial species in the midden fish inventory differed significantly from the ratios in current fish checklists.

Results
Data were collected from 68 middens distributed in 19 locations along the coast of three states of the Southeast Region of Brazil: Espírito Santo (ES), Rio de Janeiro (RJ) and São Paulo (SP) (Figure 1).The location with the highest number of middens (12 sites, 17.65%) was Paraty in the state of Rio de Janeiro, which also had the highest number of documented sites (53, 77.95%).Conversely, Espírito Santo had the lowest number of middens (2, 2.94%; Table 1).From these total of 68 middens, 49 of them had records of 14 C radiocarbonic dates (Figure 2).Occupation time ranged from 8,182 BP (Sambaqui de Camboinhas) to 675 BP (Sítio do Major).However, the majority of them were built and occupied during the period defined by Walker et al. (2012) as Late Holocene.
A total of 142 fish species were inventoried, and most taxa belonged to class Osteichthyes (105, 73.94%).Sciaenidae was the most represented family with 21 species, and Cynoscion Gill, 1861 was the genus with the highest number of species, seven in total (Table 2).Of the Chondrichthyes (37, 26.06%), the family with the highest number of species was Carcharhinidae with 17 species, and the most representative genus was Carcharhinus Blainville, 1816 with 12 species (Table 3).
The site with the highest species richness was the midden Sambaqui do Algodão in Angra dos Reis with 71 inventoried species and a relative species richness value of 0.5 (Table 1).Most of the inventoried species (63.38%) may be considered rare because they were recorded in no more than five of the 68 study sites.Conversely, Micropogonias furnieri (Desmarest, 1823) and Pogonias cromis (Linnaeus, 1766) had the highest frequencies of occurrence, being found in 53 (relative frequency = 0.78) and 48 (relative frequency = 0.71) of the sites, respectively.
The biogeographic, ecological and economic data showed that most of the identified fish are widely distributed in the Western Atlantic (59.72%) and inhabit estuarine environments (53.99%), while most species have a demersal habit (35.92%) and exhibit oceanic migratory behaviour (28.87%).Lastly, the surveyed fish are predominantly carnivorous (72.54%) with some commercial value (96.48%; Figure 3).

Discussion
Middens are artificial accumulations of wildlife and cultural remains that were built by groups of pre-colonial humans during the Holocene (Lima et al. 2003, Mendes et al. 2014).Therefore, the species compositions of the organisms found in middens are presumably non-random and biased samples of natural biological communities at those sites because they were influenced or determined by various cultural factors, including food preference, the technological level of the fishing gear, harvesting and hunting artefacts, food taboos, funerary or ritualistic practices and how the materials were discarded and/or used.Therefore, some researchers believe that the faunal data from middens have selectivity biases that complicate any related inferences about ecosystems and their biodiversity (Baisre 2010, Rodrigues et al. 2016a).However, the comparison between the inventory of the marine fish identified in middens and those from general surveys of ichthyological fauna showed no significant differences in the number of species either with or without commercial value, indicating that middens contain data that are not solely applicable to prehistoric fisheries.Such wildlife remains apparently represent the fauna existing at the time that the archaeological sites were created but are also repositories of broader biodiversity data, despite any bias associated with the composition of zoo-archaeological remains (Lindbladh et al. 2007, Froyd & Willis 2008).
In a recent study using taxonomic tests, Faria et al. (2014) showed that the malacological taxonomic diversity in the Tarioba midden (Rio de Janeiro, Brazil) was not significantly different from that of a comprehensive list of the mollusc species from the entire coast of the state of Rio de Janeiro.Those findings and the results of the present study suggest that middens may contain key indicators of past biodiversity, despite their limitations, and furthermore, some studies of middens have shown detectable changes in species composition over time (Dalzell 1998, Lotze & Milewski 2004, Rosenberg et al. 2005, Maschner et al. 2008, Souza et al. 2016).
Studies focused on inventorying the fish species in middens have usually involved a limited number of sites (sampling areas).For example, Kloker et al. ( 2010) recorded 17 fish species from two sites on the south coast of Brazil (Santa Catarina state).In contrast, as part of a greater sampling effort, Lopes et al. (2016) recorded 97 fish species in 13 sites located on the coast of Rio de Janeiro, and in this study, the study area corresponded to 68 middens distributed over 1,000 km of the southeast coast of Brazil.
In using even greater effort than that undertaken by Lopes et al. (2016), this study used data which came from different kinds of publications (scientific articles, books, thesis, dissertations, monographs, technical reports etc) encompassing 48 years  of studies in the field.Therefore, the data compiled here came from a myriad of objectives and methodologies, for example, primary data which came from excavations were originated since superficial sampling till total material recovery.Following excavation the material recovered were dry sieved or under current water using different mesh sizes (2 to 10mm).Identification of the zoo-archaeological vestiges was done by handling different manuals and reference collections.Due to that the list recovered was carefully scrutinized.Criteria such as using only the more inclusive taxa and species with biogeographic range defined were used.Furthermore, the Linean definition of the species was fully checked for ambiguities and classification changes.In using these criteria any inconvenience related to the heterogeneity of sources were surpassed and the methodological choice gave an extensive baseline of fishes biodiversity during the Holocene in the Brazilian Coast.The species richness from the midden fish inventory in this study was lower than that of current fish checklists (Bizerril & Costa 2001, Menezes 2011, speciesLink), which likely resulted from the selected sampling methods.All current checklists were developed from extensive bibliographical surveys that included studies that employed diverse methods (fishing records, scientific collections, the testimony of scientific experts, museum collection documents and environmental monitoring) as well as data accumulated from several years of academic research.In contrast, the midden records were fundamentally related to prehistoric fisheries or related cultural activities (fishing gear, ritualistic symbols, ornaments and artefacts) as well as by-catch.In all cases, the midden fish records were always informed by an understanding of prehistoric culture; that is, the midden fish inventory was constructed with data from archaeological studies of fishing cultures and thus focused on a limited number of target species.
Regarding the target species, the occurrence frequencies of M. furnieri and P. cromis in middens indicate that they were preferentially fished species.Barbosa-Guimarães (2013) observed that M. furnieri was the main fish species in Saquarema middens (Rio de Janeiro, Brazil) and thus inferred that it was the primary food of the midden peoples of that region.In turn , Souza Cunha et al. (1981) notes the presence of Pogonias sp. in the midden Sambaqui de Camboinhas (Niterói, state of Rio de Janeiro, Brazil), and the remains of that genus are commonly found in coastal middens (Kneip et al. 1975).Lopes et al. (2016) recorded M. furnieri and P. cromis as two of the three most common species in their study of Rio de Janeiro middens, and these two species are currently considered key fishery resources in the Southeast Region of Brazil (Mulato et al. 2015, Santos et al. 2016).Furthermore, estuarine, demersal and carnivorous species typically have significant commercial value, thus composing key fishing stocks (Tacon 1994, Santos & Câmara 2002, Haimovici et al. 2014), and it can be deduced that such species were critical fishing resources for midden peoples in the past.
On the one hand, the presence of species such as M. furnieri and P. cromis, which occur at high relative frequencies in middens, indicates that midden fish inventories contain prehistoric fishery data, but the numbers of fish with and without commercial value in middens are not significantly different from those in checklists of ichthyological fauna for the same sites.Moreover, the high number of exclusive species with low frequencies of occurrence in middens corroborates the hypothesis that midden fish records contain key data on Holocene ichthyological fauna and that such species are most likely by-catch.Additionally, the occurrence frequencies show that it is unlikely that midden peoples from neighbouring regions consumed different or unique species.Thus, the results from this study indicate that middens contain data on midden fishing and culture as well as past biodiversity.
Biodiversity inventories are essential for establishing baselines that inform species management and conservation measures (Gordillo et al. 2014), especially those related to endangered species, including fish.Currently, the effects of overfishing, pollution, invasive species and other ecological impacts have reduced marine ichthyological diversity (Povey & Keough 1991, Brosnan & Crumrine 1994, Polunin & Roberts 1996, Costello et al. 2010).Therefore, the study of ichthyological midden remains is a key tool for understanding prehistoric biodiversity, enabling the establishment of a historical perspective and thus more complete baselines to inform more effective management measures and reduce the threat of extinction currently faced by marine fishes.
In summary, the midden inventory of the Holocene marine fish of the southeast coast of Brazil contains data on prehistoric fisheries, which is supported by the high number of species with low frequencies of occurrence (or unique species) as well as by chi-squared tests that failed to show significant differences between the midden fish inventory and current ichthyofauna checklists.Thus, the results from this study clearly indicate that zoo-archaeological fish remains are key evidence of Holocene biodiversity.

Figure 1 .
Figure 1.Map of the Southeast Region of Brazil with the locations of the inventoried middens.

Figure 2 .
Figure 2. Graphic with the 14 C radiocarbonic dates of the 49 inventoried middens of the Southeast Region of Brazil.In the x axis are the middens (codes defined at Table 1) and in the y axis are the ranges of 14 C radiocarbonic dating (given in year before present) found in the literature.The different periods of the Holocene were defined based in Walker et al. (2012): Early Holocene (11,700 ~ 8,200 BP), Middle Holocene (8,200 ~ 4,200 BP) and Late Holocene (4,200 BP ~ till today).

Figure 3 .
Figure 3. Biogeographical, ecological and economic data for the inventoried fish.A = Distribution; B = Environment; C = Habit; D = Behaviour; E = Feeding guild; F = Commercial value.

Table 1 .
Middens inventoried in the Southeast Region of Brazil with absolute (Rspp) and relative (relative Rspp) species richness and the associated references from the literature.

Table 4 .
Number of species from current fish inventories and middens from Rio de Janeiro (RJ), São Paulo (SP), Espírito Santo (ES) and the entire Southeast Region.