Superficial sediments and their relation to polyehaete families in a subtropieal embayment, Mexico

María Green Ruiz,Nuria Méndez

doi:10.15517/rbt.v46i2.19433

Abstract

The soft bottoms in front of Mazatlan Bay and "Isla de la Piedra" Peninsula were studied to produce maps (depth, grain size and organic matter content in sediments). Sixty samples were óbtained with a 30 x 30 van Veen grab (4-21 m depth) and polychaetes were extracted from 21 subsamples. Grain size ranged from -1.05 phi (gravel) to 3 .81 phi (very fine sand), with fme sand predominl\ting. Organic matter content in sediment was 0.91-3.06 % (most values = 1-2 %). Thirty polychaete families (905 individuals/m2 in mean) were found, and Cirratulidae, Spionidae, Onuphidae, and Pilargiidae were domiuant. Pearson's correlation of grain size.

Highlights

The benthic fauna inhabiting soft bottoms presents a strong relationship with the size and texture of sediments
Because of the scarcity of studies related to the nature of soft bottorns in front of Mazatlan, the purpose of this study is to characterize the zone by means of depth and the spatial distribution of sediments according to their grain size and organic matter content
The spatial distribution of sediments showed that fine sand was wel1 represented in almost the whole study area (Fig. 2b)

Summary

Introduction

The benthic fauna inhabiting soft bottoms presents a strong relationship with the size and texture of sediments. The most recent studies conceming the polychaete fauna inhabiting shallow soft bottoms of Mazatlan Bay correspond to Solís Weiss (1983) and Arias-González (1984), who revised material collected at depths between 3.5 and 33 m. The latter related the most frequent species with sediments grain size and concluded that this parameter may affect, among others, the polychaete distribution. Because of the scarcity of studies related to the nature of soft bottorns in front of Mazatlan, the purpose of this study is to characterize the zone by means of depth and the spatial distribution of sediments according to their grain size and organic matter content. The distribution of the polychaete families related to such characterization is analyzed

Objectives

Methods

Results